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Title:
COLOUR FORMING COMPOSITIONS
Document Type and Number:
WIPO Patent Application WO/2020/065321
Kind Code:
A1
Abstract:
A composition for forming an image on or within a substrate, the composition comprising: (a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and (b) two additional components each capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour.

Inventors:
PUGH THOMAS (GB)
STEWART DAVID (GB)
SIMON BINTO (GB)
TWEEDIE JASON (GB)
COOK RICHARD (GB)
Application Number:
PCT/GB2019/052716
Publication Date:
April 02, 2020
Filing Date:
September 26, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
DATALASE LTD (GB)
International Classes:
G03C1/73; B41M5/28; C07C233/09; G03F7/025
Domestic Patent References:
WO2012114121A22012-08-30
WO2013068729A12013-05-16
WO2010001171A12010-01-07
WO2011121265A12011-10-06
WO2010112940A12010-10-07
WO2010029331A22010-03-18
WO2012114121A22012-08-30
WO2009093028A22009-07-30
WO2010001171A12010-01-07
WO2010029329A12010-03-18
WO2013068729A12013-05-16
WO2015015200A12015-02-05
WO2015199219A12015-12-30
Foreign References:
US7485403B22009-02-03
US8932797B22015-01-13
EP2368875A12011-09-28
Other References:
CHEMICAL ABSTRACTS, Columbus, Ohio, US; abstract no. 12411-64-2
Attorney, Agent or Firm:
GILL JENNINGS & EVERY LLP et al. (GB)
Download PDF:
Claims:
Claims

1. A composition comprising:

(a) an activatable component capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour.

2. The composition according to claim 1 , wherein the activatable component is a diacetylene compound.

3. The composition according to claim 1 or 2, wherein the activatable component is a diacetylene compound of formula (I): wherein x is from 2 to 12, preferably 2 to 10, and more preferably 2 to 8; o

L is selected from an amide having the formula: Y\ HH , and an ester

O having the formula L: LH , preferably L is an amide having the formula Q is selected from a cyclopropyl and a -(CH2)y-CH3 linear alkyl chain, y being selected from 1 to 20, preferably 5 to 19, and more preferably 7 to 17; and

T is selected from hydrogen, a -(CH2)X(CH3) linear alkyl chain wherein x is defined as above for formula (I), and -(CH2)X-L-Q, wherein x, L and Q are as defined above for formula (I).

4. The composition according to claim 3, wherein the diacetylene compound is symmetrical.

5. The composition according to claim 3 or 4, wherein the activatable component is a diacetylene compound of formula (II):

wherein x is from 4 to 8, and Q is selected from cyclopropyl and a - (CH2)y(CH3) linear alkyl chain wherein y is 7 to 17.

6. The composition according to any preceding claim, wherein the activatable component is a diacetylene compound selected from:

N 1 , N22-dioctadecyldocosa-10, 12-diynediamide, N 1 , N22- dihexadecyldocosa-10-12-diynediamide, N 1 , N22-ditetradecyldocosa-

10, 12-diynediamide, N 1 , N22-didodecyldocosa-10, 12-diynediamide,

N 1 , N22-didecyldocosa-10, 12-diynediamide, N 1 , N22-dioctyldocosa-10,12- diynediamide, N1 , N22-dihexyldocosa-10,12-diynediamide, and N1 ,N22- dicyclopropyldocosa-10,12-diynediamide; preferably N1 ,N22- dioctadecyldocosa-10, 12-diynediamide, N 1 , N22-dihexadecyldocosa-

10,12-diynediamide, N 1 , N22-ditetradecyldocosa-10, 12-diynediamide,

N1 ,N22-didodecyldocosa-10,12-diynediamide, and N1 ,N22- dicyclopropyldocosa-10, 12-diynediamide.

7. The composition according to any preceding claim, wherein the applied transition stimulus is radiation selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, and microwave radiation with a wavelength of from 1 mm to 1 m; preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm; more preferably, the applied transition stimulus is selected ultraviolet (UV) radiation with a wavelength of from 100 to 400 nm. 8. The composition according to any preceding claim, wherein the activation temperature is a temperature of from 40 to 140°C, preferably from 60 to 140 °C, and more preferably from 70 to 140 °C.

The composition according to any preceding claim, wherein the activation temperature is applied using radiation selected from visible radiation with a wavelength of from 400 to 700 nm, and infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, including near-infrared radiation (NIR) with a wavelength of from 700 to 1600 nm; preferably the activation temperature is applied using visible radiation with a wavelength of from 400 to 700 nm, infrared (IR) radiation with a wavelength of 10600 nm, and near-infrared (NIR) radiation with a wavelength of from 700 to 1600 nm.

10. The composition according to any preceding claim, wherein, if required, the additional applied stimulus is radiation selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, and microwave radiation with a wavelength of from 1 mm to 1 m; preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm; more preferably, the applied transition stimulus is selected ultraviolet (UV) radiation with a wavelength of from 100 to 400 nm.

11. The composition according to any preceding claim, wherein, if required, the additional temperature is a temperature of from 50 to 300 °C, preferably, the additional temperature is from 50 to 250 °C, or even from 80 to 200 °C. 12. The composition according to claim 11 , wherein the additional temperature is applied using radiation selected from visible radiation with a wavelength of from 400 to 700 nm, and infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, including near-infrared radiation (NIR) with a wavelength of from 700 to 1600 nm; preferably the activation temperature is applied using visible radiation with a wavelength of from

400 to 700 nm, infrared (IR) radiation with a wavelength of 10600 nm, and near-infrared (NIR) radiation with a wavelength of from 700 to 1600 nm.

13. The composition according to any preceding claim, wherein the two additional components are independently selected from groups (b1 ) to

(b5):

(b1 ) a pyrazole (thio)semicarbazone compound, preferably a pyrazolone semicarbazone compound;

(b2) a keto acid compound; (b3) a leuco dye;

(b4) a compound formed from a salicylic aldehyde or salicylic ketone compound; and

(b5) an oxyanion of a multivalent metal.

14. The composition according to any of claims 1 to 13, wherein the two additional components are independently selected from (b1 ) a pyrazole

(thio)semicarbazone compound, (b2) a keto acid compound, (b3) a leuco dye, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound.

15. The composition according to any of claims 1 to 13, wherein the two additional components are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound, and (b5) an oxyanion of a multivalent metal.

16. The composition according to any of claims 1 to 13, wherein the two additional components are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound. 17. The composition according to any of claims 13 to 16, wherein the pyrazole (thio)semicarbazone compound of (b1 ) has the following formula (III):

wherein each of A, B, C’ and D are independently selected from: Ci-is alkyl; -CCI3; -CF3; C6-12 aryl optionally substituted with CM S alkoxy, -

CN, -CF3, halogen, -N02, or CM S alkyl; a heterocyclic ring and a heteroaryl.

18. The composition according to claim 17, wherein A is selected from C6-12 aryl optionally substituted with CM S alkoxy, -CN, -CF3, halogen, -N02, or Ci-is alkyl, preferably from C6-s aryl, and more preferably phenyl.

19. The composition according to claim 17 or 18, wherein B is selected from Ci-is alkyl and C6-12 aryl optionally substituted with CM S alkoxy, -CN, -CF3, halogen, -N02, or CM S alkyl, preferably from Ci-4 alkyl and C6-s aryl, and more preferably from methyl and phenyl.

20. The composition according to any of claims 17 to 19, wherein C is selected from C6-12 aryl optionally substituted with CM S alkoxy, -CN, -CF3, halogen, -N02, or CM S alkyl; -CCI3; and CM S alkyl; preferably from C6-s aryl optionally substituted with Ci-4 alkoxy, -CN, -CF3 or -N02; -CCI3; and Ci-4 alkyl, and more preferably, from phenyl, 4-methoxy phenyl, 4- cyanophenyl, 4-(trifluoromethyl)phenyl, 4-nitrophenyl; -CCI3; and C(CH3)3.

21. The composition according to any of claims 17 to 20, wherein D is selected from C6-12 aryl optionally substituted with CM S alkoxy, -CN, -CF3, halogen, -N02, or CM S alkyl, preferably from C6-s aryl, and more preferably phenyl.

22. The composition according to claim 17, wherein the pyrazole (thio)semicarbazone compound of (b1 ) has the following formula (IV):

wherein B is selected from CM S alkyl and C6-12 aryl optionally substituted with Ci-is alkoxy, -CN, -CF3, halogen, -N02, or CM S alkyl, preferably from Ci-4 alkyl and C6-s aryl, and more preferably from methyl and phenyl, and

C is selected from C6-12 aryl optionally substituted with Ci-i8 alkoxy, -CN, - CF3, halogen, -N02, or CM S alkyl; -CCI3; and CM S alkyl; preferably from C6-8 aryl optionally substituted with Ci-4 alkoxy, -CN, -CF3 or -N02; -CCI3; and Ci-4 alkyl, and more preferably, from phenyl, 4-methoxy phenyl, 4- cyanophenyl, 4-(trifluoromethyl)phenyl, 4-nitrophenyl; -CCI3; and C(CH3)3.

23. The composition according to any of claims 17 to 22, wherein the pyrazole (thio) semicarbazone compound is selected from (£)-2-((5-hydroxy-1 ,3- diphenyl-1 /-/-pyrazol-4-yl)(phenyl)methylene)-A/-phenylhydrazine-1 - carboxamide (B and C are phenyl), (£)-2-((5-hydroxy-3-methyl-1 -phenyl- 1 /-/-pyrazol-4-yl)(phenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B is methyl and C is phenyl), (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4- yl)(4-nitrophenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B is phenyl and C is 4-nitrophenyl), (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/- pyrazol-4-yl)(4-(trifluoromethyl)phenyl)methylene)-A/-phenylhydrazine-1 - carboxamide (B is phenyl and C is 4-(trifluoromethyl)phenyl), (£)- 2-((5- hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4-yl)(4-methoxyphenyl)methylene)-A/- phenylhydrazine-1 -carboxamide (B is phenyl and C is 4-methoxyphenyl), (£)-2-((5-hydroxy-3-methyl-1 -phenyl-1 /-/-pyrazol-4-yl)(4-

(trifluoromethyl)phenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B is methyl and C is 4-(trifluoromethyl)phenyl), and (E)-2-((4- cyanophenyl)(3-hydroxy-2,5-diphenyl-2,3-dihydro-1 H-pyrazol-4- yl)methylene)-N-phenylhydrazine-1 -carboxamide (B is phenyl, and C is 4- cyanophenyl); preferably, the pyrazole (thio)semicarbazone compound is selected from (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4- yl)(phenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B and C are phenyl), £)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4-yl)(4-

(trifluoromethyl)phenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B is phenyl and C is 4-(trifluoromethyl)phenyl), and (E)-2-((4- cyanophenyl)(3-hydroxy-2,5-diphenyl-2,3-dihydro-1 H-pyrazol-4- yl)methylene)-N-phenylhydrazine-1 -carboxamide (B is phenyl, and C is 4- cyanophenyl). 24. The composition according to any of claims 13 to 16, wherein the keto acid compound (b2) is of formula (V):

wherein Xia, X2a, and X3a are independently selected from C, N, B and S; the two R groups may be the same or different, and are independently selected from: hydrogen; Ci-i8alkyl; C6-i2aryl optionally substituted with Ci-i8 alkoxy, -CN, -CF3, -N02, halogen, or Ci-i8 alkyl; halogen; -N02; -CF3; -OR3; -NR32; -CN; -SR3; -COR3; -C02R3; and -CONR32; wherein R3 is selected from an alkali metal; hydrogen; Ci-i8alkyl; and C6-i2 aryl optionally substituted with Ci-i8 alkoxy, -CN, -CF3, -N02, halogen, or Ci-i8 alkyl; or both R groups, together with the nitrogen atom to which they are attached, join together to form a cyclic amino group, wherein the cyclic amino group is optionally substituted with Ci-i8 alkoxy, -CN, -CF3, -N02, halogen, or CM S alkyl;

A may be the same as or different to B’ (defined below), and is independently selected from: hydrogen; Ci-i8alkyl; C6-i2 aryl optionally substituted with CM S alkoxy, -CN, -CF3, -N02, halogen, or CM S alkyl; a heterocyclic ring; a heteroaryl; halogen; -N02; -CF3; -OR3; -NR32; -CN; - SR3; -COR3; -C02R3; -CONR32; wherein R3 is selected from an alkali metal; hydrogen; Ci-i8alkyl; and C6-i2 aryl optionally substituted with CM S alkoxy, -CN, -CF3, -N02, halogen, or Ci-i8 alkyl; and

R1 is selected from

wherein Xib, X2b, X3b and X4b are independently selected from C, N, B and S; and B’ is the same or different to A and is independently selected from hydrogen; CM S alkyl; C6-i2 aryl optionally substituted with CM S alkoxy, -CN, -CF3, -N02, halogen, or CM S alkyl; a heterocyclic ring; a heteroaryl; halogen; -N02; -CF3; -OR3; -NR32; -CN; -SR3; -COR3; -C02R3; -CONR32; wherein R3 is selected from an alkali metal; hydrogen; Ci_ i8alkyl; and C6-i2 aryl optionally substituted with Ci-i8 alkoxy, -CN, -CF3, - N02, halogen, Ci-i8 alkyl, hydroxyl (-OH), or -NR2 wherein R is as defined above.. 25. The composition according to claim 24, wherein the keto acid compound (b2) has the formula (VI):

wherein Xia, X2a, X3a, Xib, X2b, X3b and X4b, R, A and B’ are as in claim 24 for formula (V). 26. The composition according to claim 24 or 25, wherein the keto acid compound (b2) has the formula (VII):

wherein R and B’ are as for formula (V); preferably, the two R groups are the same and are selected from Ci_ i8alkyl; and C6-i2aryl optionally substituted with Ci-i8 alkoxy, -CN, -CF3, -

N02, halogen, or Ci-i8 alkyl; and more preferably, the two R groups are the same and Ci-i8 alkyl, more preferably Ci-6 alkyl; preferably, B’ is independently selected from hydrogen; -N02 and halogen; more preferably, hydrogen and chlorine, and most preferably hydrogen.

27. The composition according to any of claims 24 to 26, wherein the keto acid compound is selected from2-(4-(dimethylamino)-2- hydroxybenzoyl)benzoic acid, 2-(4-(dibutylamino)-2- hydroxybenzoyl)benzoic acid, 2-(4-(diethylamino)-2- hydroxybenzoyl)benzoic acid, and 2,3,4,5-tetrachloro-6-(4-(diethylamino)-

2-hydroxybenzoyl)benzoic acid, preferably, 2-(4-(dimethylamino)-2- hydroxybenzoyl)benzoic acid, 2-(4-(dibutylamino)-2- hydroxybenzoyl)benzoic acid, and 2-(4-(diethylamino)-2- hydroxybenzoyl)benzoic acid. 28. The composition according to any of claims 13 to 16, wherein the leuco dye (b3) is selected from 6-(dimethylamino)-3,3-bis [4-(dimethylamino) phenyl] phthalide (Chameleon Blue 3), 7-[4-(diethylamino)-2- ethoxyphenyl]-7-(2-methyl-1 -octyl-1 H-indol-3-yl) furo[3,4-b]pyridin-5(7H)- one (Chameleon Blue 8), 3,3'-bis(1 -n-octyl-2-methylindol-3-yl)phthalide (Chameleon Red 5), 2-anilino-3-diethylamino-6-methylfluoran

(Chameleon Black 1 , ODB-1 ), 2-anilino-6-dibutylamino-3-methylfluoran, (Chameleon Black 2, ODB-2), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6- phenyl-4-pyridinyl]- benzenamine (Chameleon Yellow 10), 6'-

(diethylamino)-2'-[(dimethylphenyl) amino]-3'-methylspiro [isobenzofuran- 1 (3H),9'-[9H]xanthene]-3-one (Chameleon Black 15); all commercially available from Chameleon Speciality Chemicals Limited;

29. The composition according to any of claims 13 to 16, wherein (b4) the compound formed from a salicylic aldehyde or salicylic ketone compound has the following formula (VIII):

wherein R1 and R2 may be the same or different and are independently selected from hydrogen; halogen; hydroxyl; Ci-i8 alkoxy; Ci-i8 alkyl; Ci-i8 cycloalkyl; a primary, secondary or tertiary amino groups; -CN; -N02; - CF3, -COOH, -COR3, -CONR32; a heterocyclic ring; a heteroaryl and C6- i2aryl optionally substituted with Ci-i8 alkoxy, -CN, -CF3, -N02, halogen, or Ci-18 alkyl; Xia, X2a, X3a, X4a, Xib, X2b, X3b and X4b are independently selected from C, N or S; and

R3 and R4 may be the same or different and are independently selected from hydrogen, Ci-i8alkyl, C6-i2aryl and Ci-i8alkyl-C6-i2aryl.

30. The composition according to any of claims 13 to 16, wherein (b4) the compound formed from a salicylic aldehyde or salicylic ketone compound has the following formula (IX):

wherein R1 , R2, R3 and R4, and Xia, X2a, X3a, X4a, Xib, X2b, Xsb and X4b are in claim 29 for formula (VI II).

31 . The composition according to claim 29 or 30, wherein R1 and R2 are the same and are selected from hydrogen; halogen; hydroxyl; CMS alkoxy including methoxy; CMS alkyl including methyl, tertiary butyl and isopropyl; a secondary amino group (including -NR2 wherein R is Ci-6 alkyl such as diethylamino and dimethylamino); -CN, -N02, -CF3, -COOH; C6-i2aryl optionally substituted with CMS alkoxy, -CN, -CF3, -N02, halogen, or Ci-is alkyl, including phenyl; and a heterocyclic ring such as pyridyl; preferably, R1 and R2 are the same and are selected from hydrogen; halogen; hydroxyl; Ci-i8alkoxy including methoxy; a secondary amino group (including -NR2 wherein R is Ci-6 alkyl such as diethylamino and dimethylamino); and N02. 32. The composition according to any of claims 29 to 31 , wherein; Xia, X2a, X3a, X4a, Xib, X2b, X3b and X4b are independently selected from C or N; preferably Xia, X2a, X3a, X4a, Xib, X2b, X3b and X4b are C.

33. The composition according to any of claims 29 to 32, wherein R3 and R4 are the same and are selected from hydrogen and Ci_i2alkyl; preferably R3 and R4 are the same and are selected from hydrogen and Ci-6alkyl; and more preferably R3 and R4 are the same and are hydrogen.

34. The composition according to any of claims 29 to 33, wherein (b4) the compound formed from a salicylic aldehyde or salicylic ketone compound is 2,2'-((1 E, 1 'E)-hydrazine-1 ,2-diylidenebis(methaneylylidene))diphenol, 6,6'-((1 E, 1 '£)-hydrazine-1 ,2-diylidenebis(methaneylylidene))bis(3- nitrophenol), 3,3’-((1 E, 1’E)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(benzene-1 ,2-diol), 6,6’-((1 E,1’E)- hydrazine-1 ,2-diylidenebis(methaneylylidene))bis(4-bromo-2- methoxyphenol), 6,6’-((1 E, TE)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(3-(diethylamino)phenol), 2,2’- ((1 E, TE)-hydrazine-1 ,2-diylidenebis(ethan-1 -yl-1 -ylidene))diphenol and

1 , 1’-((1 E, TE)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(naphthalene-2-ol); preferably, the compound formed from a salicylic aldehyde or salicylic ketone compound is 6,6’-((1 E, TE)-hydrazine-1 ,2-diylidenebis(methaneylylidene))bis(3- nitrophenol).

35. The composition according to any of claims 13 to 16, wherein the oxyanion of a multivalent metal (b5) is ammonium octamolybdate (AOM).

36. A substrate comprising the composition according to any of claimsl to 35 applied to or incorporated within. 37. A method of forming a substrate according to claim 36, the method comprising applying to or incorporating within the substrate the composition according to any of claims 1 to 35.

38. A method of forming colour on or within a substrate comprising a composition according to any of claims 1 to 35 applied to or incorporated within, the method comprising applying to the composition on or within the substrate the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components of the composition.

39. A method of forming an image on or within a substrate, comprising a composition according to any of claims 1 to 35 applied to or incorporated within, the method comprising applying to the composition on or within the substrate the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components of the composition, and thereby create an image on or within the substrate. 40. A use of the composition according to any of claims 1 to 35 in the formation of colour on or within a substrate.

41. A use of the composition according to any of claims 1 to 35 in the formation of an image on or within a substrate.

42. A substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprise:

(a) an activatable component capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate.

43. The substrate according to claim 41 , wherein the activatable component is as defined in claims 2 to 6.

44. The substrate according to claim 41 or 42, wherein the applied transition stimulus is radiation selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, and microwave radiation with a wavelength of from 1 mm to 1 m; preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm more preferably, the applied transition stimulus is selected ultraviolet (UV) radiation with a wavelength of from

100 to 400 nm.

45. The substrate according to any of claims 41 to 44, wherein the activation temperature is as defined in claims 8 and 9.

46. The substrate according to any of claims 41 to 45, wherein, if required, the additional applied stimulus is radiation selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, and microwave radiation with a wavelength of from 1 mm to 1 m; preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm more preferably, the applied transition stimulus is selected ultraviolet (UV) radiation with a wavelength of from 100 to 400 nm.

47. The substrate according to any of claims 41 to 46, wherein , if required, the additional temperature is as defined in claims 11 and 12. 48. The substrate according to any of claims 41 to 47, wherein the two additional components are as defined in any of claims 13 to 35.

49. A method of forming a substrate according to any of claims 41 to 48 , the method comprising applying to a substrate the plurality of discrete layers.

50. A method of forming colour on a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprises:

(a) an activatable component capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate; the method comprising applying to the substrate, the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components at localised positions.

51. A method of forming an image on a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprises: (a) an activatable component capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and (b) two additional components each capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate; the method comprising applying to the substrate, the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components at localised positions, and thereby forming an image on the substrate.

Description:
Colour Forming Compositions

Field of the Invention

The present invention relates to compositions, in particular compositions for forming an image on or within a substrate.

Background to the Invention

In-line digital printing is a process known for the formation of greyscale, single- coloured (monochromic), or multi-coloured images on or within substrates. Radiation from a laser source(s) effects laser-reactive components in compositions applied on or incorporated within substrates such that they change colour upon application of the radiation. However, problems arise in that when using these laser-reactive components, access to a full colour gamut and the full range of colours required to form multi-coloured images is difficult to achieve.

There is therefore a desire to provide a laser-reactive composition for the formation of an image on or within a substrate that can provide a broad colour gamut for in-line digital printing via laser excitation, enabling real-time marketing and personalisation response capabilities for users. In order to achieve this, it is important to have compositions that have components able to form stable predictable colours upon application of radiation or other stimuli. Summary of the Invention

According to a first aspect of the present invention, there is provided a composition, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour. According to a second aspect of the present invention, there is provided a substrate comprising a composition applied to or incorporated within, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour. According to a third aspect of the present invention, there is provided a method of forming a substrate comprising applying to or incorporating within the substrate a composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour.

According to a fourth aspect of the present invention, there is provided a method of forming colour on or within a substrate comprising a composition applied to or incorporated within, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour; and wherein the method comprises applying to the composition on or within the substrate the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components of the composition.

According to a fifth aspect of the present invention, there is provided a method of forming an image on or within a substrate, comprising a composition applied to or incorporated within, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour; and wherein the method comprises applying to the composition on or within the substrate the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components of the composition, and thereby create an image on or within the substrate. According to a sixth aspect of the present invention, there is provided a use of a composition in the formation of colour on or within a substrate comprising a composition applied to or incorporated within, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour. According to a seventh aspect of the present invention, there is provided a use of a composition in the formation of an image on or within a substrate comprising a composition applied to or incorporated within, the composition comprising:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour.

According to an eighth aspect of the present invention, there is provided a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprise: (a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and (b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate. According to a ninth aspect of the present invention there is provided a method of forming a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprises:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate, the method comprising applying to a substrate the plurality of discrete layers.

According to a tenth aspect of the present invention, there is provided a method of forming colour on a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprises: (a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and (b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate; the method comprising applying to the substrate the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components at localised positions.

According to an eleventh aspect of the present invention, there is provided a method of forming an image on a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprises:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate; the method comprising applying to the substrate the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components at localised positions, and thereby forming an image on the substrate.

Detailed Description of the Invention

The intention of the present invention is to provide a laser-reactive composition that is capable of providing colour or an image on or within a substrate using a laser source(s) to manipulate colour changes in the components of the laser- reactive composition at localised positions so as to create a single- or multi- coloured image having any desired colour.

The present invention is of particular use in in-line printing, and allows compositions to be prepared with components that can respond to radiation or other stimuli to generate predictable colours for image formation. A broad colour gamut can therefore be achieved using these laser-reactive components.

"Non-coloured state" and like terms as used herein, refers to the natural state of a component before the applied transition stimulus, additional applied stimulus or additional temperature is applied to it. The non-coloured state of a component may be white, off-white or colourless i.e. clear, or have reduced, or low visible, colour, i.e. is paler in colour (a lighter shade or less intense colour) than a coloured state of the same colour. Alternatively, the natural state (non- coloured state) of a component may possess an initial colour which will change following application of the applied transition stimulus, additional applied stimulus or additional temperature to a more intense colour (coloured state) or a different colour (coloured state). It will therefore be appreciated by a skilled person that, in the natural state, the component may often appear to display a colour, but that when compared with a coloured state of the same component, it will be paler in colour, i.e. less intensely coloured, or a different colour. It will be appreciated that, when the non-coloured state of a component is colourless, any underlying colour of the substrate on which the component is applied to or incorporated within will be visible. "Coloured state" and like terms as used herein, refers to the state of a component in which the component displays a colour, i.e. is substantially or highly coloured, in the visible spectrum and to a human eye. The "coloured state" will be more intensely coloured that the "non-coloured state" of the same component. This may be a more intense colouration of the same colour, but also may be a more intense colouration of a different colour to that of the non- coloured state as discussed above. In relation to the term "coloured state", the singular encompasses the plural and vice versa. For example, although reference is made herein to "a" coloured state, the term encompasses one or more coloured states. It will be appreciated that some components may have two coloured states, such as a first and a second coloured state, each of the first and second coloured states displaying a different colour. By the term "colour" and like terms as used herein, is meant the colours and hues of the visible light colour spectrum, i.e. red, orange, yellow, green, blue and violet, in addition to magenta, pink, purple, cyan, turquoise, brown and black, and combinations thereof. Both primary and secondary colours are encompassed i.e. it will be appreciated by a skilled person that a coloured state formed by a component may have a primary or secondary colour. In the context of the present invention, the term may also be used to describe differing shades of each of the colours of the visible light colour spectrum, in addition to magenta, purple, pink, cyan, turquoise, brown and black, and combinations thereof.

"Stable coloured state" and like terms as used herein, refers to the coloured state of a component that is stable under ambient conditions, i.e. maintains essentially its colour under ambient conditions. "Ambient conditions" and like terms as used herein, refers to the normal range of conditions of the surrounding environment to which the components are exposed, i.e. the range of temperatures, pressures and atmospheric conditions to which the components are exposed during use, storage and otherwise. This includes solar radiation including electromagnetic radiation of X-rays, ultraviolet (UV) and infrared (IR) radiation. Typically, ambient conditions include a temperature of from 10 to 35 °C, a pressure of from 20 to 100 kPa, and the environment is typically an oxygen-containing atmosphere. It will be appreciated by a skilled person that the required stability of the coloured state of a component will be dependent upon the application for which a substrate having the composition and therefore the component applied to or incorporated within is intended to be used. For example, if the composition comprising the component is to be utilised in a laser reactive patch for a disposable item such as a hot or cold beverage container, the required stability of the coloured state of the component of the composition will only need to be for a relatively short period of time, for example, a number of hours such as 6 to 12 hours, or a number of days such as 3 or 4 days. Whereas, if the composition comprising the component is to be utilised in a laser-reactive composition applied on or incorporated within a cosmetic container or outdoor signage, the required stability of the coloured state of the component will be greater, for example, a number of months, or even a number of years for outdoor signage uses. In general however, stable under ambient conditions is meant that when exposed to ambient conditions for at least a number of hours or a number of days, such as for at least two weeks, the coloured state maintains essentially its colour. Preferably, the component will permanently remain in the particular coloured state. Accordingly, it is preferred that a component remains in the coloured state for at least 3 days, preferably for at least 4 days, more preferably for at least 1 or even at least 2 weeks, and most preferably, for at least 2 months.

"Monochromic" or "single-coloured image" and like terms used herein, refer to an image that is human or machine readable and has a single colour that is visible to the human eye. In the context of the present invention, the non- coloured state can form part of the monochromic image. In particular, when the non-coloured state of a component is non-colour, i.e. is white, off-white or colourless, the non-coloured state can form part of the monochromic image.

"Multi-coloured image" and like terms as used herein, refers to an image that is human or machine readable having multiple colours, i.e. displaying 2 or more colours that are visible to the human eye. In the context of the present invention, the non-coloured state can form part of the multi-coloured image. In particular, when the non-coloured state of a component is non-colour, i.e. is white, off-white or colourless, the non-coloured state can form part of the multi-coloured image. The term "image" incorporates, but is not limited to: text, pictures, logos, graphics, figures and symbols. The term also incorporates both single- and multi-coloured images. It will be appreciated that it is the manipulation of the components of the composition that facilitates the formation of an image.

"Transitioning" and "transition" and like terms as used herein, refer to the components changing irreversibly from a non-coloured state to a coloured state upon application of the applied transition stimulus, additional applied stimulus or additional temperature, or from a first coloured state to a second coloured state as applicable upon application of the applied temperature. It will be appreciated by a skilled person that these are intentional transitions facilitated by the application of the applied transition stimulus, applied temperature, additional applied stimulus or additional applied temperature as required to the components . By the term "irreversibly" is meant that once the coloured state of the component has been formed, the coloured state of the component will be stable under ambient conditions.

"Printing", "in-line digital printing" or "laser printing" and like terms as used herein, refer to the process of using radiation to achieve colour and form an image on a substrate

"Radiation" and like terms as used herein, refers to energy in the form of waves or particles, and in particular, refers to electromagnetic radiation such as ultraviolet (UV), visible, near-infrared (NIR), and infrared (IR) particle radiation, e.g. alpha (a) radiation, beta (b) radiation, neutron radiation and plasma. It will be appreciated that, in the context of the present invention, a distinction is made between radiation of greater than 400 nm, e.g. near-infrared radiation, which causes vibrational, conductive and radiative excitation to the components upon application and therefore provides a‘temperature’, and radiation of 400 nm or less (e.g. ultraviolet radiation), or microwave radiation, which does not. In the context of the present invention, the "temperature" applied to the compositions and compounds is intended to include the temperature provided to the compositions and compounds through the application of thermal energy in different conductive, radiative and vibrational forms. As discussed, this may be through application of radiation of greater than 400 nm. By the term "laser source(s)" and like terms as used herein includes any suitable commercial or non-commercial laser source(s).

"Activated" and like terms as used herein in relation to the activatable component, refer to the non-coloured state of the component when it is capable of undergoing a transition to a coloured state. It will be appreciated by a skilled person that the non-coloured state can either exist in (a) an unactivated form, i.e. incapable of undergoing a transition from the non-coloured state to a coloured state when the applied transition stimulus is applied to the composition and thus, the activatable component; or (b) an activated form, i.e. capable of undergoing a transition from the non-coloured state to a coloured state when the applied transition stimulus is applied to the composition and thus, the activatable component. "Activation" and like terms as used herein in relation to the activatable component, refer to the process by which the non-coloured state of the component is activated, i.e. changes from an unactivated to activated form. This is facilitated by the application of an activation temperature.

All references to particular chemical compounds herein are to be interpreted as covering the compounds per se, and also, where appropriate, derivatives, hydrates, solvates, complexes, isomers, tautomers thereof.

The activatable component may be selected from any suitable component. The activatable component may be a diacetylene compound, i.e. a compound comprising a diacetylene moiety The activatable component may be a diacetylene compound having the following formula (I): wherein x is from 2 to 12, preferably 2 to 10, and more preferably 2 to 8; O

\ N-]

L is selected from an amide having the formula: H , and an ester having the formula: , ¾A· 0 ^_ t preferably L is an amide having the formula y H j ,

Q is selected from a cyclopropyl and a -(CH 2 ) y -CH 3 linear alkyl chain, y being selected from 1 to 20, preferably 5 to 19, and more preferably 5 to 17; and T is selected from hydrogen, a -(CH 2 ) X (CH 3 ) linear alkyl chain wherein x is defined as above for formula (I), and -(CH 2 ) X -L-Q, wherein x, L and Q are as defined above for formula (I).

It will be appreciated by a skilled person that the diacetylene compound can be either symmetrical or unsymmetrical, i.e. T is -(CH 2 ) X -L-Q and the values of x, L and Q are the same as those on the other side of the diacetylene moiety (symmetrical), or T is hydrogen, a -(CH 2 ) X (CH 3 ) linear alkyl chain, or -(CH 2 ) X -L-Q and the values of x, L and Q are not the same on both sides of the diacetylene moiety (unsymmetrical). Preferably, T is -(CH 2 ) X -L-Q and the values of x, L and Q are the same on both side of the diacetylene moiety, such that the diacetylene compound is symmetrical.

The activatable component may be a diacetylene compound of formula (II):

wherein x is from 4 to 8, and Q is selected from cyclopropyl and a -(CH 2 ) y (CH 3 ) linear alkyl chain wherein y is 5 to 17. Examples of suitable diacetylene compounds include, but are not limited to the following: N1 ,N22-dioctadecyldocosa-10,12-diynediamide, N1 ,N22- dihexadecyldocosa-10-12-diynediamide, N 1 , N22-ditetradecyldocosa-10,12- diynediamide, N1 ,N22-didodecyldocosa-10,12-diynediamide, N1 ,N22- didecyldocosa-10, 12-diynediamide, N 1 , N22-dioctyldocosa-10, 12-diynediamide, N1 , N22-dihexyldocosa-10,12-diynediamide, and N1 ,N22-dicyclopropyldocosa-

10.12-diynediamide.

Preferably, the diacetylene compound is a diacetylene compound selected from N 1 , N22-dioctadecyldocosa-10, 12-diynediamide, N 1 , N22-dihexadecyldocosa-

10.12-diynediamide, N 1 , N22-ditetradecyldocosa-10, 12-diynediamide, N 1 , N22- didodecyldocosa-10, 12-diynediamide, and N 1 , N22-dicyclopropyldocosa-10, 12- diynediamide.

Diacetylene compounds are well known to a skilled person as compounds capable of forming colour. Typical diacetylene compounds are disclosed for this purpose in WO 2012/114121 , the content of which is incorporated herein by reference. Suitable examples are taught in W02009/093028, WO2010/001171 , WO2010/029329, and WO2013/068729, the content of each of which is incorporated herein by reference. Known methods of synthesis of diacetylene compounds include the formation of a reactive acid chloride and subsequent addition of an amine or alcohol, or the formation of a mixed anhydride and subsequent reactions with an amine or alcohol. It will be appreciated by a skilled person that when the diacetylene compounds of the present invention are in the non-coloured state, they are considered to be monomers. Typically, the diacetylene compounds have two coloured states, such as a first and second coloured state. These first coloured states of the diacetylene compounds of the present invention are formed on account of polymerisation of these monomers upon exposure to the applied transition stimulus. Polymerisation of at least a portion of the monomers enables the formation of the coloured state of the diacetylene compounds. In addition, without being bound by theory, the inventors consider that the different first and second coloured states are achieved through changes in conjugation of the diacetylene polymer, i.e. a structural change. The second coloured states of the diacetylene compounds can be accessed from the first coloured state by application of applied temperature. It will be understood be a skilled person that a coloured state of the activatable component is stable under ambient conditions.

The activatable component may be present in the composition in any suitable amount. It will be appreciated that the amount of activatable component present in the composition will depend upon the other components present in the composition, the application method utilised for applying or incorporating the composition to or into the substrate, the substrate type and the desired end use of the substrate.

Preferably, the composition comprises from 0.1 to 50 %, such as from 0.1 to 40 %, or even from 3 to 30 % of the activatable component based on the total solid weight of the composition. Preferably, the composition comprises from 5 to 25 % of the activatable component based on the total solid weight of the composition.

The applied transition stimulus facilitates the transition of the activatable component from the non-coloured to a coloured state. As discussed above, in the context of the present invention, when the activatable component is a diacetylene compound, the diacetylene compound typically has two coloured state, a first and a second coloured state, the first and second coloured states displaying different colours. In the context of the present invention, application of the applied transition stimulus facilitates a transition of the activatable component from the non-coloured to a first coloured state. The second coloured state may be subsequently accessed by the application of an applied temperature to the first coloured state. The applied temperature may be 50 to 200 °C such as from 500 to 180 °C, and be applied by the same means as defined below for the activation temperature.

The applied transition stimulus applied to the activatable component is radiation. It will be appreciated that the radiation will be the radiation required to facilitate a transition of the activatable component from the non-coloured to a coloured state. The radiation is selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, and microwave radiation with a wavelength of from 1 mm to 1 m. Preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm, More preferably, the applied transition stimulus is ultraviolet (UV) radiation with a wavelength of from 100 to 400 nm.

It will be appreciated that from the radiation and wavelength ranges detailed herein for the applied transition stimulus relating to the activatable component, a skilled person would select a specific applied transition stimulus as required to achieve the desired transition of the activatable component. It will be appreciated that the specifically selected applied transition stimulus will differ depending upon the components in the composition.

The applied transition stimulus applied to the activatable component of the composition may be applied to the composition and thus the activatable component using any suitable means. Suitable means include laser excitation through application of radiation to the composition and thus the activatable component by a laser source(s). It will be understood by a skilled person that the applied transition stimulus may be applied at localised positions to selectively develop the coloured state of the activatable component at these localised positions in the composition. These localised positions may overlap with each other. Alternatively, it will be appreciated by a skilled person that the applied transition stimulus may be applied to the composition on or within a substrate by flood illumination, meaning that the composition as a whole is flooded with radiation. This can be done using any suitable lamp or bulb, such as a UV lamp, or medium pressure mercury or amalgam lamp or microwave powered UV lamp, a Xe, Hg or XeHg arc (broadband UV sources); a germicidal lamp, a diode bar; or LED(s). When a broadband UV source is utilised, it will be appreciated that a range of wavelengths over the 10 to 400 nm range will be emitted. It will be understood by a skilled person that the radiation is applied to the composition for an appropriate amount of time required to facilitate the transition of the activatable component from the non-coloured state to a coloured state. Typically the time required to deliver sufficient radiation will depend upon the power of the means used to apply radiation and the method of application i.e. at localised positions, or by flood illumination. For example, in one embodiment, the applied transition stimulus may be applied to the activatable component for less than 120 seconds (such as between 30 to 110 seconds, or even between 75 to 105 seconds), or for less than 60 seconds, such as for less than 20 seconds, or even for less than 10 seconds.

It will be appreciated that when using a laser source(s), the radiation dosage applied can be controlled by alteration of the time for which the radiation is applied, the power of the means used to apply the radiation (wattage) and thus, the fluence (amount of energy delivered per unit area) delivered by a laser source(s), i.e. J/cm 2

A coloured state of the activatable component may have any colour. It will be appreciated by a skilled person that the means used to apply the applied transition stimulus will affect the colour of the coloured state formed. For example, where a laser source(s) is used to apply the applied transition stimulus, the fluence (amount of energy delivered per unit area) may affect the colour, lightness or intensity of the coloured state formed. In the context of the present invention, the fluence is dependent upon the power of the means used to apply the applied transition stimulus (wattage), and the time for which the applied transition stimulus is applied to a particular localised position on the substrate, which may be controlled by the scanning speed of the laser or the speed of the moving stage. These two variables can be altered to change the fluence. Where the fluence is low (e.g. lower power and/or shorter irradiation times), the coloured state of the activatable component will be of a less intense colour, and where the fluence is high (e.g. higher power and/or longer irradiation times), the coloured state of the activatable component will be of a more intense colour. In the context of the present invention, fluence values may range from 0.01 to 20 J/cm 2 , such as from 0.1 to 10 J/cm 2 and even from 0.5 to 5 J/cm 2 .

Preferably, the coloured state of the activatable component formed following the transition from the non-coloured state is blue.

In the context of the present invention, the non-coloured state of the activatable component is‘activated’ prior to the application of the applied transition stimulus such that a transition from the non-coloured state to a coloured state can occur. As detailed above,‘activation’ is the process of making the non-coloured state of the component capable of undergoing a transition from the non-coloured state to a coloured state, i.e. changing it from an unactivated form (incapable of undergoing such a transition) to an activated form (capable of undergoing such a transition). This is facilitated by the application of an activation temperature. The activation temperature may be any suitable temperature. The activation temperature may be a temperature of from 40 to 140°C. Preferably, the activation temperature is from 60 to 140 °C, and more preferably, from 70 to 140 °C.

The activation temperature may be applied to the activatable component of the composition by any suitable means. Suitable means include laser excitation through application of radiation to the composition and thus the activatable component by a laser source(s). It will be understood by a skilled person that the activation temperature may be applied to the composition at localised positions to selectively activate the non-coloured state of the activatable component at these localised positions in the composition. These localised positions may overlap with each other. Alternatively, it will be appreciated by a skilled person that the activation temperature may be applied to the activatable component by flood illumination, meaning that the composition as a whole is flooded with radiation. This may be done using a lamp or bulb, such as a IR lamp; diode bar; or LED(s). It will further be appreciated that the activation temperature may be applied to the activatable component using a conductive temperature source. Conductive temperature sources include sources of steam and hot air, lamps, hotplates, heat tunnels, LED(s), thermal print heads, thermal conductors, hot liquids and heated substrates. It will be understood by a skilled person that the activation temperature is applied to the composition for an appropriate amount of time required to activate the non-coloured state of the activatable component. Typically the time required to deliver sufficient temperature will depend upon the power of the means used to apply radiation and the method of application i.e. at localised positions, by flood illumination, or using a conductive temperature source. For example, in one embodiment, the activation temperature may be applied to the activatable component for less than 120 seconds (such as between 30 to 110 seconds, or even between 75 to 105 seconds) or for less than 60 seconds, such as for less than 20 seconds, or even for less than 10 seconds.

It will be appreciated that when applied using a laser source(s), the radiation dosage applied to achieve the activation temperature can be controlled by alteration of the time for which the radiation is applied, the power of the means used to apply the radiation (wattage) and thus, the fluence (amount of energy delivered per unit area) delivered by a laser source(s), i.e. J/cm 2

It will be appreciated by a skilled person that the activation temperature may be applied to the activatable component using a combination of the suitable means listed above, i.e. using combinations of laser excitation at localised positions, flood illumination, and a conductive temperature source. For example, in one embodiment, the activation temperature may be applied to the activatable component using laser excitation at localised positions, in addition to using a conductive thermal energy source. In addition, it will be appreciated that where the activation temperature is applied using radiation, i.e. at localised positions using a laser source(s) or by flood illumination, the composition and thus the activatable component may be exposed to a temperature in excess of the stated temperature ranges for a very short period of time, i.e. microseconds. It will be understood that this will not have any significant effect on the result to be achieved.

The activation temperature may be applied to the activatable component using radiation selected from visible radiation with a wavelength of from 400 to 700 nm, and infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, including near-infrared (NIR) radiation with a wavelength of from 700 to 1600 nm. Preferably, the activation temperature is applied using visible radiation with a wavelength of 400 to 700 nm, infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, in particular infrared (IR) radiation with a wavelength of 10600 nm (using a C0 2 laser) and near-infrared (NIR) radiation with a wavelength of from 700 to 1600 nm. It will be appreciated that from the temperature range detailed herein for the activation temperature of the activatable component, a skilled person would select a specific activation temperature as required to achieve the activation of the activatable component. It will be appreciated that the specifically selected activation temperature will differ depending upon the components in the composition.

The two additional components of the composition according to the first aspect of the present invention may be any suitable components. It will be appreciated that the selection of the activatable component and the two additional components will be selected based on the colour(s) of their coloured states that can be achieved. Furthermore, the activatable component and two additional components will be selected such that their formation of colour is triggered by different conditions. ‘Different conditions’ encompasses the differing orders of application of the applied transition stimulus, activation temperature and additional temperature or additional applied stimulus, as required, for the formation of colour for each of the two additional components and the activatable component.

The two additional components are preferably independently selected from the following component groups (b1 ) to (b5):

(b1 ) a pyrazole (thio)semicarbazone compound, preferably a pyrazolone semicarbazone compound;

(b2) a keto acid compound;

(b3) a leuco dye;

(b4) a compound formed from a salicylic aldehyde or salicylic ketone compound; and

(b5) an oxyanion of a multivalent metal.

In one embodiment, the composition does not comprise a combination of an activatable component and only components of groups (b3) and (b5). The two additional components independently selected from groups (b1 ) to (b5) are different. By different is meant that the two additional components are selected either from different groups of (b1 ) to (b5) as defined below, or are selected from the same group (b1 ) to (b5), but are selected so as to be different compounds in that group, e.g. two different leuco dyes. Preferably, the two additional components are independently selected from different groups (b1 ) to (b5).

The two additional components may be independently selected from any of the following groups (b1) to (b5): (b1) a pyrazole (thio)semicarbazone compound.

By the term "pyrazole (thio)semicarbazone compound" is meant a compound having a pyrazole group and a (thio) semicarbazone group. The brackets around thio indicate that the moeity may be present or absent. The term pyrazole group encompasses derivatives of a pyrazole group. Preferably, the pyrazole group is a pyrazolone, including the enol (C-OH) tautomer form. Preferably, the (thio) semicarbazone group is a semicarbazone.

Preferably, the pyrazole (thio)semicarbazone compound is a pyrazolone semicarbazone compound.

Preferably, the pyrazole (thio)semicarbazone compound is a compound having the formula (III):

wherein each of A, B, C and D are independently selected from:

C1-18 alkyl; -CCI 3 ; -CF 3 ; C 6 -12 aryl optionally substituted with Ci-i 8 alkoxy, -CN, - CF 3 , halogen, -N0 2 , or Ci-i 8 alkyl; a heterocyclic ring and a heteroaryl. Preferably, A is selected from C 6- 12 aryl optionally substituted with C M S alkoxy, - CN, -CF 3 , halogen, -N0 2 , or C M S alkyl, more preferably from C 6 -s aryl, and most preferably phenyl.

Preferably, B is selected from C M S alkyl and C 6- 12 aryl optionally substituted with Ci-is alkoxy, -CN, -CF 3 , halogen, -N0 2 , or C M S alkyl, more preferably from Ci -4 alkyl and C 6 -s aryl, and most preferably from methyl and phenyl.

Preferably, C is selected from C 6- 12 aryl optionally substituted with C M S alkoxy, - CN, -CF 3 , halogen, -N0 2 , or C M S alkyl; -CCI 3 ; and C M S alkyl; more preferably from C 6-8 aryl optionally substituted with Ci -4 alkoxy, -CN, -CF 3 or -N0 2 ; -CCI 3 ; and Ci -4 alkyl, and most preferably, from phenyl, 4-methoxy phenyl, 4- cyanophenyl, 4-(trifluoromethyl)phenyl, 4-nitrophenyl; -CCI 3 ; and C(CH 3 ) 3 .

Preferably, D is selected from C 6- 12 aryl optionally substituted with C M S alkoxy, - CN, -CF 3 , halogen, -N0 2 , or C M S alkyl, more preferably from C 6 -s aryl, and most preferably phenyl. The pyrazole (thio)semicarbazone compound may have the following formula (IV):

wherein B is selected from C M S alkyl and C 6- 12 aryl optionally substituted with Ci_ 18 alkoxy, -CN, -CF 3 , halogen, -N0 2 , or Ci-i 8 alkyl, preferably from Ci -4 alkyl and C 6-8 aryl, and more preferably from methyl and phenyl, and

C is selected from C 6- 12 aryl optionally substituted with C 1 -18 alkoxy, -CN, -CF 3 , halogen, -N0 2 , or C 1 -18 alkyl; -CCI 3 ; and C 1-18 alkyl; preferably from C 6 -s aryl optionally substituted with Ci -4 alkoxy, -CN, -CF 3 or -N0 2 ; -CCI 3 ; and Ci -4 alkyl, and more preferably, from phenyl, 4-methoxy phenyl, 4-cyanophenyl, 4- (trifluoromethyl)phenyl, 4-nitrophenyl; -CCI 3 ; and C(CH 3 ) 3 .

Preferably, the pyrazole (thio)semicarbazone compound is selected from (£)- 2- ((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4-yl)(phenyl)methylene)-A/- phenylhydrazine-1 -carboxamide (B and C are phenyl), (£)-2-((5-hydroxy-3- methyl-1 -phenyl-1 /-/-pyrazol-4-yl)(phenyl)methylene)-A/-phenylhydrazine-1 - carboxamide (B is methyl and C is phenyl), (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/- pyrazol-4-yl)(4-nitrophenyl)methylene)-A/-phenylhydrazine-1 -carboxamide (B is phenyl and C is 4-nitrophenyl), (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4- yl)(4-(trifluoromethyl)phenyl)methylene)-A/-phenylhydrazine- 1 -carboxamide (B is phenyl and C is 4-(trifluoromethyl)phenyl), (£)-2-((5-hydroxy-1 ,3-diphenyl-1 /-/- pyrazol-4-yl)(4-methoxyphenyl)methylene)-A/-phenylhydrazine- 1 -carboxamide (B is phenyl and C is 4-methoxyphenyl), (£)-2-((5-hydroxy-3-methyl-1 -phenyl-1 H- pyrazol-4-yl)(4-(trifluoromethyl)phenyl)methylene)-A/-phenyl hydrazine-1 - carboxamide (B is methyl and C is 4-(trifluoromethyl)phenyl), and (E)-2-((4- cyanophenyl)(3-hydroxy-2,5-diphenyl-2,3-dihydro-1 H-pyrazol-4-yl)methylene)-N- phenylhydrazine-1 -carboxamide (B is phenyl, and C is 4-cyanophenyl). More preferably, the pyrazole (thio)semicarbazone compound is selected from (£)- 2- ((5-hydroxy-1 ,3-diphenyl-1 /-/-pyrazol-4-yl)(phenyl)methylene)-A/- phenylhydrazine-1 -carboxamide (B and C are phenyl), £)-2-((5-hydroxy-1 ,3- diphenyl-1 /-/-pyrazol-4-yl)(4-(trifluoromethyl)phenyl)methylene)-A/- phenylhydrazine-1 -carboxamide (B is phenyl and C is 4-(trifluoromethyl)phenyl), and (E)-2-((4-cyanophenyl)(3-hydroxy-2,5-diphenyl-2,3-dihydro-1 H-pyrazol-4- yl)methylene)-N-phenylhydrazine-1 -carboxamide (B is phenyl, and C is 4- cyanophenyl).

All references to the components of formulas (III) and (IV) are to be interpreted as covering the components of the formulas (III) and (IV) per se, and also, all tautomers or isomers thereof.

(b2) a keto acid compound.

By the term "keto acid compound" is meant a compound having a carboxylic acid group and a ketone group. Preferably, the keto acid compound is of formula (V):

wherein Xi a , X 2a , and X 3a are independently selected from C, N, B and S; the two R groups may be the same or different, and are independently selected from: hydrogen; Ci-i 8 alkyl; C 6 -i 2 aryl optionally substituted with Ci-i 8 alkoxy, -CN, - CF 3 , -N0 2 , halogen, or C M S alkyl; halogen; -N0 2; -CF 3 ; -OR 3 ; -NR 3 2 ; -CN; -SR 3 ; - COR 3 ; -C0 2 R 3 ; and -CONR 3 2 ; wherein R 3 is selected from an alkali metal; hydrogen; Ci-i 8 alkyl; and C 6 -i 2 aryl optionally substituted with Ci-i 8 alkoxy, -CN, - CF 3 , -N0 2 , halogen, or C M S alkyl; or both R groups, together with the nitrogen atom to which they are attached, join together to form a cyclic amino group, wherein the cyclic amino group is optionally substituted with C M S alkoxy, -CN, - CF 3 , -N0 2 , halogen, or C M S alkyl .

A may be the same as or different to B’ (defined below), and is independently selected from: hydrogen; Ci-i 8 alkyl; C 6-i2 aryl optionally substituted with C M S alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl; a heterocyclic ring; a heteroaryl; halogen; -N0 2 ; -CF 3 ; -OR 3 ; -NR 3 2 ; -CN; -SR 3 ; -COR 3 ; -C0 2 R 3 ; -CONR 3 2 ; wherein R 3 is selected from an alkali metal; hydrogen; Ci-i 8 alkyl; and C 6-i2 aryl optionally substituted with C M S alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl; and R 1 is selected from

wherein Xi b , X 2b , X3 b and X 4b are independently selected from C, N, B and S; and B’ is the same or different to A and is independently selected from hydrogen; C1-18 alkyl; C 6- 12 aryl optionally substituted with C 1-18 alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl; a heterocyclic ring; a heteroaryl; halogen; -N0 2; -CF 3; - OR 3 ; -NR 3 2 ; -CN; -SR 3 ; -COR 3 ; -C0 2 R 3 ; -CONR 3 2 ; wherein R 3 is selected from an alkali metal; hydrogen; Ci-i 8 alkyl; and C 6 -i 2 aryl optionally substituted with Ci_ 18 alkoxy, -CN, -CF 3 , -N0 2 , halogen, C M S alkyl, hydroxyl (-OH), or -NR 2 wherein R is as defined above.

It will be appreciated that A and B’ may constitute a substituent at a single position on the benzene ring to which each of A and B’ relates or A and B’ may constitute multiple independently selected substituents at any of the available positions on the benzene ring to which each of A and B’ relates. For example, the benzene ring to which B’ relates may be substituted with a single substituent or up to 4 independently selected substituents.

Preferably, the keto acid compound is selected from formula (VI):

wherein Xi a , X 2a , X3 a , Xi b , X2 b , X3 b and X 4b , R, A and B’ are as described above for formula (V).

Preferably, the keto acid compound is selected from formula (VII):

wherein R and B’ are as described above for formula (V). Preferably, the two R groups are the same and are selected from Ci-i 8 alkyl; and C 6-i2 aryl optionally substituted with C M S alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl. More preferably, the two R groups are the same and C M S alkyl, more preferably Ci -6 alkyl. Preferably, B’ is independently selected from hydrogen; -N0 2 and halogen, more preferably, hydrogen and chlorine, and most preferably hydrogen.

Preferably, the keto acid compound is selected from2-(4-(dimethylamino)-2- hydroxybenzoyl)benzoic acid, 2-(4-(dibutylamino)-2-hydroxybenzoyl)benzoic acid, 2-(4-(diethylamino)-2-hydroxybenzoyl)benzoic acid, and 2, 3,4,5- tetrachloro-6-(4-(diethylamino)-2-hydroxybenzoyl)benzoic acid. More preferably, 2-(4-(dimethylamino)-2-hydroxybenzoyl)benzoic acid, 2-(4-(dibutylamino)-2- hydroxybenzoyl)benzoic acid, and 2-(4-(diethylamino)-2-hydroxybenzoyl)benzoic acid.

The keto acid compounds of formulas (V) to (VII) are commercially available, for example, they can be sourced from Chameleon Speciality Chemicals Limited. All references to the components of formulas (V) to (VII) are to be interpreted as covering the components of the formulas (V) to (VII) per se, and also, all tautomers or isomers thereof.

It is noted that in one embodiment, the keto acid compound may be in the form of a‘dimer’, whereby B’ denotes a -C0 2 R 3 group (where R 3 is hydrogen such that the benzene ring carries two carboxyl groups) and also, an independently selected -COR 3 group, where R 3 is a C 6- 12 aryl substituted with hydroxyl (-OH) and NR 2 , wherein R is as defined above for formula (V). Preferably, the -C0 2 R 3 group (where R 3 is hydrogen such that the benzene ring carries two carboxyl groups) is at X 2b and the -COR 3 group is at X 3b .

(b3) a leuco dye.

Leuco dyes are well known to a skilled person as compounds capable of forming colour. They can be photochromic (change colour on exposure to light such as UV light), chemochromic, thermochromic or halochromic (change colour on exposure to change in environmental pH). Examples of suitable leuco dyes are contained in WO2015/015200 and WO2013/068729, the content of which is incorporated by reference. Suitable leuco dyes include, but are not limited to any commercially available or chemically synthesisable leuco dye, including but not limited to: commercially available photochromic, thermochromic, chemochromic, and halochromic leuco dyes. Examples of suitable leuco dyes include, but are not limited to: spiroxazines, naphthopyrans, phthalides, fluorans, triarylmethanes, benzoxazines, quinazolines, spiropyrans, quinones, tetrazolium salts, thiazines, phenazines and oxazines.

Suitable suppliers of leuco dyes include, but are not limited to: Yamada Chemical Company Limited, Chameleon Speciality Chemicals Limited, and Connect Chemicals.

The leuco dye may be selected from: 2-Anilino-3-diethylamino-6-methylfluoran (Chameleon Black 1 ), 2-Anilino-6-dibutylamino-3-methylfluoran (Chameleon Black 2), 6-(Dimethylamino)-3,3-bis [4-(dimethylamino) phenyl] phthalide (Chameleon Blue 3), 4,4'-[(9-butyl-9H-carbazol-3-yl)methylene]bis[N-methyl-N- phenylaniline] (Chameleon Blue 4), 3,3'-Bis(1 -n-octyl-2-methylindol-3- yl)phthalide (Chameleon Red 5), 6'-(Diethylamino)-3-oxo-spiro [isobenzofuran- 1 (3H),9'-[9H] xanthene]-2'-carboxylic acid ethyl ester (Chameleon Orange 6), 7- [4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl-1 -octyl-1 H-indol-3-yl) Furo[3,4- b]pyridin-5(7H)-one (Chameleon Blue 8),

2'-(Dibenzylamino)-6'- (diethylamino)fluoran (Chameleon Blue 9), N,N-dimethyl-4-[2-[2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl] - Benzenamine (Chameleon Yellow 10), and 6'-(diethylamino)-2'-[(dimethylphenyl) amino]-3'- methylspiro [isobenzofuran-1 (3H),9'-[9H]xanthene]-3-one (chameleon Black 15).

Preferably, the leuco dye is -(dimethylamino)-3,3-bis [4-(dimethylamino) phenyl] phthalide (Chameleon Blue 3), 7-[4-(diethylamino)-2-ethoxyphenyl]-7-(2-methyl- 1 -octyl-1 H-indol-3-yl) furo[3,4-b]pyridin-5(7H)-one (Chameleon Blue 8), 3,3'- bis(1 -n-octyl-2-methylindol-3-yl)phthalide (Chameleon Red 5), 2-anilino-3- diethylamino-6-methylfluoran (Chameleon Black 1 , ODB-1 ), 2-anilino-6- dibutylamino-3-methylfluoran, (Chameleon Black 2, ODB-2), N,N-dimethyl-4-[2- [2-(octyloxy)phenyl]-6-phenyl-4-pyridinyl]- benzenamine (Chameleon Yellow 10), 6'-(diethylamino)-2'-[(dimethylphenyl) amino]-3'-methylspiro [isobenzofuran- 1 (3H),9'-[9H]xanthene]-3-one (Chameleon Black 15); all commercially available from Chameleon Speciality Chemicals Limited.

(b4) a compound formed from a salicylic aldehyde or salicylic ketone compound.

By the term "a compound formed from a salicylic aldehyde or salicylic ketone compound" is meant a compound formed from a parent salicylic aldehyde or salicylic ketone compound (aldehyde or ketone derivatives of salicylic acid).

Preferably, the compound formed from a salicylic aldehyde or salicylic ketone compound is a compound formed from the condensation reaction of a linked primary diamine and independently selected from two salicylic aldehyde or salicylic ketone compounds.

By the term "linked primary diamine" is meant a compound comprising two primary amine groups joined by a carbon chain of 0 to 20 carbon atoms, preferably 0 to 10 carbon atoms, more preferably 0 to 8 carbon atoms, and most preferably 0 to 6 carbon atoms.

Preferably, the compound formed from a salicylic aldehyde or salicylic ketone compound is a compound formed from the condensation reaction of hydrazine and independently selected from two salicylic aldehyde or salicylic ketone compounds. The compound formed from a salicylic aldehyde or salicylic ketone compound may have the following formula (VIII):

wherein R 1 and R 2 may be the same or different and are independently selected from hydrogen; halogen; hydroxyl; C M S alkoxy; C M S alkyl; C M S cycloalkyl; a primary, secondary or tertiary amino group; -CN; -N0 2 ; -CF 3 ; -COOH; -COR 3 ; - CONR 3 2 ; a heterocyclic ring; a heteroaryl and Ce-^aryl optionally substituted with C1-18 alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl; R 3 and R 4 may be the same or different and are independently selected from hydrogen, Ci-i 8 alkyl, Ce-^aryl, and Ci-i 8 alkyl-C 6 -i2aryl; and

Xia, X 2a , X 3a , X 4a , Xi b , X 2b , Xs b and X 4b are independently selected from C, N or S.

It will be appreciated that R 1 and R 2 may constitute a substituent at a single position on the benzene ring to which each of R 1 and R 2 relates or R 1 and R 2 may constitute multiple independently selected substituents at any of the available positions on the benzene ring to which each of R 1 and R 2 relates. For example, R 1 or R 2 may constitute a single substituent on the benzene ring to which it relates, or R 1 or R 2 may constitute two substituents on the benzene ring to which it relates, the two substituents being different and situated at different positions on the benzene ring. For example, R 1 or R 2 may constitute a single substituent on the benzene ring to which it relates, or R 1 or R 2 may constitute two substituents on the benzene ring to which it relates, the two substituents being different and situated at different available positions on the benzene ring.

Preferably, R 1 and R 2 are the same and are selected from hydrogen; halogen; hydroxyl; C M S alkoxy including methoxy; C M S alkyl including methyl, tertiary butyl and isopropyl; a secondary amino group (including -NR 2 wherein R is Ci -6 alkyl such as diethylamino and dimethylamino); -CN, -N0 2 , -CF 3 , -COOH; C 6- i 2 aryl optionally substituted with C M S alkoxy, -CN, -CF 3 , -N0 2 , halogen, or C M S alkyl, including phenyl; and a heterocyclic ring such as pyridyl. More preferably, R 1 and R 2 are the same and are selected from hydrogen; halogen; hydroxyl; Ci_ i 8 alkoxy including methoxy; a secondary amino group (including -NR 2 wherein R is Ci-e alkyl such as diethylamino and dimethylamino); and N0 2 .

Preferably, R 3 and R 4 are the same and are selected from hydrogen and Ci_ i 2 alkyl. More preferably, R 3 and R 4 are the same and are selected from hydrogen and Ci -6 alkyl. Most preferably, R 3 and R 4 are the same and are hydrogen.

Preferably, Xi a , X 2a , X3 a , X 4a , Xi b , X2 b , X3 b and X 4b are independently selected from C or N. More preferably, Xi a , X 2a , X3 a , X 4a , Xi b , X2 b , X3 b and X 4b are C.

Or, the compound formed from a salicylic aldehyde or salicylic ketone compound may have the following formula (IX):

wherein R 1 , R 2 , R 3 , R 4 and Xi a , X 2a , X3 a , X 4a , Xi b , X2 b , X3 b and X 4b are as defined above for formula (VIII).

Preferably, the compound formed from a salicylic aldehyde or salicylic ketone compound is 2,2'-((1 E,TE)-hydrazine-1 ,2- diylidenebis(methaneylylidene))diphenol, 6,6'-((1 E, 1 '£)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(3-nitrophenol), 3,3’-((1 E,1’E)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(benzene-1 ,2-diol), 6,6’-((1 E,1’E)-hydrazine- 1 ,2-diylidenebis(methaneylylidene))bis(4-bromo-2-methoxypheno l), 6,6’-

((1 E, 1’E)-hydrazine-1 ,2-diylidenebis(methaneylylidene))bis(3- (diethylamino)phenol), 2,2’-((1 E, 1’E)-hydrazine-1 ,2-diylidenebis(ethan-1 -yl-1 - ylidene))diphenol and 1 ,1’-((1 E, 1’E)-hydrazine-1 ,2- diylidenebis(methaneylylidene))bis(naphthalene-2-ol). Most preferably, the compound formed from a salicylic aldehyde or salicylic ketone compound is 6,6’- ((1 E, 1’E)-hydrazine-1 ,2-diylidenebis(methaneylylidene))bis(3-nitrophenol).

All references to the compounds of formulas (VIII) and (IX) are to be interpreted as covering the compounds of the formulas (VIII) and (IX) per se, and also, all tautomers thereof.

(b5) an oxyanion of a multivalent metal.

The use of oxyanions of multivalent metals in laser-markable compositions is disclosed in US7485403, the content of which is incorporated herein by reference. A particularly preferred oxyanion is ammonium octamolybdate (NH 4 ) 4 MO 8 0 26 or“AOM”, which is a commercially available molybdenum composition with the CAS number 12411-64-2. The AOM pigment will typically be formulated together with a binder, e.g. a polymeric binder, in the compositions of the invention. Suitable oxyanions include molybdate, tungstate or analogous transition metal compounds, including di- and hept-molybdates. Preferably, the oxyanion of a multivalent metal is ammonium octamolybdate (AOM).

It will be appreciated by a skilled person that the selection of the additional applied stimulus or additional temperature is dependent upon the nature of the selected additional component. When an additional component is a compound of formula (III) or (IV), a compound of formula (V), (VI) or (VII), a leuco dye or a compound of formula (VIII) or (IX), the additional applied stimulus may be utilised to facilitate a transition from the non-coloured state to a coloured state of the additional component. Further, when the additional component is a compound of formula (III) or (IV), a compound of formula (V), (VI) or (VII), a leuco dye, an oxyanion of a multivalent metal or a compound of formula (VIII) or (IX), the additional temperature may be utilised to facilitate a transition from the non-coloured state to a coloured state of the additional component.

When the additional component is a compound of formula (III) or (IV), the additional component may be accompanied in the composition by an acid or base-generating agent. It will be appreciated by a skilled person that the acid or base-generating agent and the additional component of formula (III) or (IV) interact to achieve colour formation. The acid- or base-generating agent is present to facilitate a pH change through generation of acid or base (for the acid- generating or base-generating agents respectively) upon application of the additional applied stimulus or additional temperature to the composition and thus the compound of formula (III) or (IV) and acid or base-generating agent. This acid or base generation facilitates the transition of the additional component of formula (III) or (IV) to transition from a non-coloured state to a coloured state. By‘acid’ is meant any molecular entity or chemical species capable of donating a hydrogen (proton) or capable of forming a covalent bond with an electron pair. By‘base’ is meant a chemical species or molecular entity having an available pair of electrons capable of forming a covalent bond with a proton, or with a vacant orbital of some other species.

Suitable acid-generating agents include any suitable commercially available or chemically synthesisable acid-generating agents. Suitable acid-generating agents include, but are not limited to the following: thermal acid-generating agents (TAGs) based on amine salts of borobenzilate and tri-n-butylammonium borodisalicylate; photoacid-generating agents such as but not limited to triphenylsulfonium triflate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium perluorobutane sulfonate, triphenylsulfonium trifluoromethylsulfonate, N-phenylbis(trifluoromethanesulfonimide), Bisphenol derivatives including but not limited to bisphenol A, bisphenol F, bisphenol S, bisphenol E, bisphenol B, bisphenol AF, bisphenol AP, and bisphenol BP. Suitable photoacid-generating agents include those described in US 8932797, the content of which is incorporated herein by reference.

Suitable base-generating agents include any suitable commercially available or chemically synthesisable base-generating agents. Suitable base-generating agents include, but are not limited to the following: thermal base-generating agents such as n-phenyliminodiacetic acid, 1 ,2-bis(2-aminophenoxy)-ethane- N,N,N’,N’-tetraacetic acid, and N-methylpyridinium oxalate; and photobasic- generating agents such as 9-anthrylmethyl 4’-nitrophenylcarbonate, 9- anthrylmethyl 1 -piperidinecarboxylate, and 2-anthraquinonylmethyl 4’nitrophenylcarbonate. Suitable thermal base-generating agents include those described in WO2015199219 and photobase-generating agents include those described in EP2368875, the content of each of which is incorporated herein by reference.

It will be understood by a skilled person that the selection of the acid- or base- generating agent is dependent upon the particular compound of formula (III) or (I IV) utilised in the composition. The requirement of either an acid- or a base- generating agent can be determined by a skilled person.

It will further be appreciated by a skilled person that the selection of the additional applied stimulus or additional temperature is dependent upon the nature of the acid- or base-generating agent accompanying the compound of formula (III) or (IV). It will be appreciated by a skilled person that the additional applied stimulus is utilised to facilitate a transition when a photoacid- or photobase-generating agent is present in relation to the compound of formula (INI) or (IV), and the additional temperature is utilised to facilitate a transition when a thermal acid- or base-generating agent is present in relation to the compound of formula (III) or (IV).

When the additional component is a compound of formula (V), (VI) or (VII) or a leuco dye, the additional component is accompanied in the composition by an acid-generating agent, the acid-generating agent being as described above. The additional applied stimulus or additional temperature is applied to the composition as described above to facilitate a transition from the non-coloured to the coloured state of the additional component. It will be appreciated by a skilled person that the acid-generating agent and the additional component of formula (V), (VI) or (VII) or a leuco dye interact to achieve colour formation. The acid- generating agent is present to facilitate a pH change through generation of acid upon application of the additional applied stimulus or additional temperature to the composition and thus the additional component and acid -generating agent. This acid generation facilitates the transition of the additional component of formula (V), (VI) or (VII) or the leuco dye from a non-coloured state to a coloured state.

It will be understood by a skilled person that the selection of the acid-generating agent is dependent upon the particular compound of formula (V), (VI) or (VII), or leuco dye utilised in the composition. It will further be appreciated by the skilled person that the selection of the additional applied stimulus or additional temperature is dependent upon the nature of the acid-generating agent accompanying the compound of formula (V), (VI) or (VII), or the leuco dye. It will be appreciated by a skilled person that the additional applied stimulus is utilised to facilitate a transition when a photoacid-generating agent is present in relation to the compound of formula (V), (VI) or (VII), or lecuo dye, and the additional temperature is utilised to facilitate a transition when a thermal acid-generating agent is present in relation to the compound of formula (V), (VI) or (VII), or a leuco dye.

When the additional component is a compound of formula (VIII) or (IX), the additional component is preferably accompanied in the composition by an acid- or base-generating agent, the acid- or base-generating agent being as described above. The additional applied stimulus or additional temperature is applied to the composition as described above to facilitate a transition from the non- coloured to the coloured state of the compound of formula (VIII) or (IX). It will be appreciated by a skilled person that the acid or base-generating agent and the additional component of formula (VIII) or (IX) interact to achieve colour formation. The acid- or base-generating agent is present to facilitate a pH change through generation of acid or base upon application of the additional applied stimulus or additional temperature to the composition and thus the additional component and acid- or base-generating agent. This acid or base generation facilitates the transition of the additional component of formula (VIII) or (IX) to transition from a non-coloured state to a coloured state.

It will be understood by a skilled person that the selection of the acid- or base- generating agent is dependent upon the particular compound of formula (VIII) or (IX) utilised in the composition. The requirement of either an acid- or a base- generating agent can be determined by a skilled person.

It will further be appreciated by a skilled person that the selection of the additional applied stimulus or additional temperature is dependent upon the nature of the acid- or base-generating agent accompanying the compound of formula (VIII) or (IX). It will be appreciated by a skilled person that the additional applied stimulus is utilised to facilitate a transition when a photoacid- or photobase-generating agent is present in relation to the compound of formula (VIII) or (IX), and the additional temperature is utilised to facilitate a transition when a thermal acid- or base-generating agent is present in relation to the compound of formula (VIII) or (IX).

The additional applied stimulus is radiation. It will be appreciated that the radiation will be the radiation required to facilitate a transition of the additional compound from the non-coloured to a coloured state. The radiation selected will therefore be dependent upon the additional component present in the composition. The radiation is selected from gamma radiation with a wavelength of less than 0.01 nm, X-ray radiation with a wavelength of from 0.01 to 10 nm, and microwave radiation with a wavelength of from 1 mm to 1 m. Preferably, the additional applied stimulus is selected ultraviolet (UV) radiation with a wavelength of from 10 to 400 nm. More preferably, the additional applied stimulus is selected from ultraviolet (UV) radiation with a wavelength of from 100 to 400 nm. It will be appreciated that from the radiation and wavelength ranges detailed herein for the additional component, a skilled person would select a specific additional applied stimulus as required to achieve the desired transition of the additional component from a non-coloured to a coloured state. It will be appreciated that the specifically selected additional applied stimuli will differ depending upon the components in the composition.

The additional applied stimulus may be applied to the additional component of the composition by any suitable means. Suitable means include laser excitation through application of radiation to the composition and thus the fourth component by a laser source(s). It will be understood by a skilled person that the additional applied stimulus may be applied to the composition at localised positions to selectively develop the coloured state of the additional component at these localised positions in the composition. These localised positions may overlap with each other. Alternatively, it will be appreciated by a skilled person that the additional applied stimulus may be applied to the composition on or within the substrate by flood illumination, meaning that the composition as a whole is flooded with radiation. This can be done using any suitable lamp or bulb, such as a UV lamp, or medium pressure mercury or amalgam lamp or microwave powered UV lamp, a Xe, Hg or XeHg arc (broadband UV sources); a germicidal lamp, a diode bar; or LED(s). When a broadband UV source is utilised, it will be appreciated by a skilled person that a range of wavelengths will be emitted over the 10 to 400 nm range. It will also be understood by a skilled person that the radiation is applied to the composition for an appropriate amount of time required to facilitate the transition of the additional component from the non-coloured state to the coloured state. Typically the time required to deliver sufficient radiation will depend upon the power of the means used to apply radiation and the method of application i.e. at localised positions, or by flood illumination. For example, in one embodiment, the additional applied stimulus may be applied to the additional component for less than 120 seconds (such as between 30 to 110 seconds, or even between 75 to 105 seconds), or for less than 60 seconds, such as for less than 20 seconds, or even for less than 10 seconds. It will be appreciated that when applied using a laser source(s), the radiation dosage for the additional applied stimulus can be controlled by alteration of the time for which the radiation is applied, the power of the means used to apply the radiation (wattage) and thus, the fluence (amount of energy delivered per unit area) delivered by a laser source(s), i.e. J/cm 2

The additional temperature may be any suitable temperature. It will be appreciated by a skilled person that the additional temperature will be a temperature required to facilitate a transition of the additional component from the non-coloured to a coloured state. The additional temperature will therefore be selected dependent upon the additional component present in the composition. The additional temperature may be a temperature of from 50 to 300 °C. Preferably, the additional temperature is from 50 to 250 °C, or even from 80 to 200 °C.

The additional temperature may be applied to the additional component of the composition by any suitable means. Suitable means include laser excitation through application of radiation to the composition and thus the additional component by a laser source(s). It will be understood by a skilled person that the additional temperature may be applied to the composition at localised positions to selectively develop the coloured state of the additional component at these localised positions in the composition. These localised positions may overlap with each other. Alternatively, it will be appreciated by a skilled person that the additional temperature may be applied to the additional component by flood illumination, meaning that the composition as a whole is flooded with radiation. This may be done using a lamp or bulb, such as a IR lamp; diode bar; or LED(s). It will further be appreciated that the additional temperature may be applied to the additional component using a conductive temperature source. Conductive temperature sources include sources of steam and hot air, lamps, heat tunnels, hotplates, LED(s), thermal print heads, thermal conductors, hot liquids and heated substrates. It will be understood by a skilled person that the additional temperature is applied to the composition for an appropriate amount of time required to facilitate the transition of the additional component from the non- coloured to the coloured state. Typically the time required to deliver sufficient temperature will depend upon the power of the means used to apply radiation and the method of application i.e. at localised positions, by flood illumination, or using a conductive temperature source. For example, in one embodiment, the additional temperature may be applied to the additional component for less than 120 seconds (such as between 30 to 110 seconds, or even between 75 to 105 seconds), or for less than 60 seconds, such as for less than 20 seconds, or even for less than 10 seconds.

It will be appreciated that when applied using a laser source(s), the additional temperature can be controlled by alteration of the time for which the radiation is applied, the power of the means used to apply the radiation (wattage) and thus, the fluence (amount of energy delivered per unit area) delivered by a laser source(s), i.e. J/cm 2

It will be appreciated by a skilled person that the additional temperature may be applied to the additional component using a combination of the suitable means listed above, i.e. using combinations of laser excitation at localised positions, flood illumination, and a conductive temperature source. For example, in one embodiment, the additional temperature may be applied to the additional component using laser excitation at localised positions, in addition to using a conductive thermal energy source.

In addition, it will be appreciated that where the additional temperature is applied using radiation, i.e. at localised positions using a laser source(s) or by flood illumination, the composition and thus the additional component may be exposed to a temperature in excess of the stated temperature ranges for a very short period of time, i.e. microseconds. It will be understood that this will not have any significant effect on the result to be achieved.

The additional temperature may be applied to the additional component using radiation selected from visible radiation with a wavelength of from 400 to 700 nm, and infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, including near-infrared (NIR) radiation with a wavelength of from 700 to 1600 nm. Preferably, the additional temperature is applied using infrared (IR) radiation with a wavelength of from 700 nm to 1 mm, infrared radiation with a wavelength of 10600 nm (using a C0 2 laser), near-infrared (NIR) radiation with a wavelength of 700 to 1600 nm, and visible radiation with a wavelength of from 400 to 700 nm.

It will be appreciated that from the temperature and wavelength ranges detailed herein for the additional component, a skilled person would select a specific additional temperature as required to achieve the desired transition of the additional component. It will be appreciated that the specifically selected additional temperature will differ depending upon the components in the composition.

The coloured state of the additional component may have any colour. It will be appreciated by a skilled person that the means used to apply the additional applied stimulus or additional temperature will affect the colour of the coloured state formed. For example, where a laser source(s) is used to apply the additional applied stimulus or additional temperature, the fluence (amount of energy delivered per unit area) may affect the colour, lightness and intensity of the coloured state of the additional component formed. In the context of the present invention, the fluence is dependent upon the power of the means used to apply the additional applied stimulus or additional temperature (wattage), and the time for which the additional applied stimulus or additional temperature is applied to a particular localised position on the substrate, which can be controlled by the scanning speed of the laser or the speed of the moving stage. These two variables can be altered to change the fluence. Where the fluence is low (e.g. lower power and/or shorter irradiation times), the coloured state of the additional component will be of a less intense colour, and where the fluence is high (e.g. higher power and/or longer irradiation times), the coloured state of the additional component will be of a more intense colour. Changing the fluence may also result in the additional component changing colour. For example, low fluence may form a coloured state of the additional component having a yellow colour, and higher fluence may form the same coloured state but having an orange or red colour. This is particularly applicable for (b1 ), (b2) and (b4). In the context of the present invention, fluence values may range from 0.01 to 20 J/cm 2 , such as from 0.1 to 10 J/cm 2 and even from 0.5 to 5 J/cm 2 Further, it will be appreciated by a skilled person that the required fluence from the additional applied stimulus or additional temperature to facilitate a transition from the non-coloured state to a coloured state of the additional component may be different to the required fluence from the applied transition stimulus. Preferably, the required fluence from the additional applied stimulus or additional temperature will be different to the require fluence from the applied transition stimulus.

It will be understood by a skilled person that if an acid- or base-generating agent accompanies the additional component in the composition according to the first aspect of the present invention, the acid- or base-generating agent will not affect the activatable component.

It will be appreciated by a skilled person that the two additional components of the composition according to the first aspect of the present invention cannot be selected to both by accompanied by an acid- or base-generating agent, i.e. the composition may only comprise one acid- or base-generating agent. Either the two additional components will be selected such that only one requires an acid- or base-generating agent, or in certain instances, the acid- or base-generating agent associated with one of the two components will also interact with the other of the two components as discussed above.

Preferably, the additional components are selected from a pyrazole (thio)semicarbazone compound, an oxyanion of a multivalent metal, a leuco dye and a keto acid compound. More preferably, the additional components are an oxyanion of a multivalent metal in combination with a pyrazole

(thio)semicarbazone or a keto acid compound, or a pyrazole

(thio)semicarbazone in combination with a leuco dye.

It will be understood by a skilled person that a coloured state of the two additional components are stable under ambient conditions.

It will be appreciated that a composition comprising the activatable component and two additional component enables the production of a broad range of colours in the formation of an image. The different applied transition stimulus, activation temperature and additional applied stimulus or additional temperature can be applied in different combinations as required across the whole composition or at particular localised positions, enabling the formation many different colours. It will be appreciated that the stimuli and temperatures used are dependent upon the components present in the composition. The invention thus enables the formation of desired single- and multi-coloured images with a broad colour gamut.

Preferably, the colours of the coloured states of the two additional components are independently selected from red, orange, black and yellow.

The additional components may individually be present in the composition in any suitable amount. It will be appreciated that the amount of the additional components individually present in the composition will depend upon the other components present in the composition, the application method utilised for applying or incorporating the composition to or into the substrate, the substrate type and the desired end use of the substrate.

Preferably, the composition comprises from 0.1 to 50%, such as from 0.1 to 40 %, or even from 3 to 30 % of an additional component based on the total solid weight of the composition. Most preferably, the composition comprises from 5 to 30 % of the additional component based on the total solid weight of the composition.

If required, the acid or base-generating agent relating to an individual additional component may be individually present in the composition in any suitable amount. Preferably, the ratio of the acid or base-generating agent to the additional component to which it is related based on the total solid weight of the composition is between 4:1 to 1 :4, more preferably between 3:1 to 1 :3, and most preferably, between 2:1 to 1 :2. Preferably, the composition comprises from 0 to 50 %, such as from 5 to 40 %, or even from 5 to 35% of the acid or base- generating agent based on the total solid weight of the composition. Most preferably, the composition comprises from 10 to 40 %, or even 10 to 35% of the acid or base-generating agent based on the total solid weight of the composition. Preferably, the two additional components in the composition according to the first aspect of the present invention are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, (b3) a leuco dye, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound. Accordingly, the composition according to the first aspect of the present invention comprises: a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and wherein the two additional components are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, (b3) a leuco dye, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound.

Groups (b1 ) to (b4) are as described above.

Alternatively, preferably the two additional components in the composition according to the first aspect of the present invention are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound, and (b5) an oxyanion of a multivalent metal. Accordingly, the composition according to the first aspect of the present invention comprises: a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and wherein the two additional components are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound, and (b5) an oxyanion of a multivalent metal.

Groups (b1 ), (b2), (b4) and (b5) are as described above. Alternatively, preferably the two additional components in the composition according to the first aspect of the present invention are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound. Accordingly, the composition according to the first aspect of the present invention comprises: a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and wherein the two additional components are independently selected from (b1 ) a pyrazole (thio)semicarbazone compound, (b2) a keto acid compound, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound.

Groups (b1 ), (b2) and (b4) are as described above.

Preferably, the two additional components in the composition according to the first aspect of the present invention are independently selected from (b1 ) a pyrazole (thio)semicarbazone and any of (b2) a keto acid compound, (b3) a leuco dye, (b4) a compound formed form a salicylic aldehyde or salicylic ketone compound, and (b5) an oxyanion of a multivalent metal.

Alternatively, preferably the two additional components in the composition according to the first aspect of the present invention are independently selected from (b5) an oxyanion of a multivalent metal and either of (b2) a keto acid compound, and (b4) a compound formed from a salicylic aldehyde or salicylic ketone compound.

Preferably, the composition comprises an activatable component, a keto acid compound and an oxyanion of a multivalent metal.

The composition according to the first aspect of the present invention may further comprise a binder. Suitable binders will be well known to a person skilled in the art. Examples of suitable binders include, but are not limited to the following: polymeric binders such as acrylic polymers, styrene polymers and hydrogenated products thereof; vinyl polymers; polyolefins and hydrogenated or epoxidised products thereof; aldehyde-containing polymers; epoxide-containing polymers; polyamides; polyesters; polyurethanes; sulphone-containing polymers; natural products and derivatives thereof; and combinations thereof. The binder may be present in the composition in any suitable amount. Preferably, the composition comprises from 1 to 50 %, such as from 5 to 40 % and most preferably, from 10 to 35 % of binder based on the total solid weight of the composition. The composition according to the first aspect of the present invention may further comprise a near-infrared (NIR) absorber. It will be appreciated that an NIR absorber may be utilised when NIR radiation is to be utilised, the NIR absorber being capable of enhancing absorption of the NIR radiation. Examples of suitable NIR absorbers include, but are not limited to the following: inorganic copper salts such as copper (II) hydroxyl phosphate; organic NIR dyes and pigments such as N,N,N’,N’-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoro-antimonate); non-stoichiometric inorganic compounds such as reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxide (tungsten bronze), reduced antimony tin oxide, or doped metal oxides such as aluminium-doped zinc oxide (AZO) and fluorine-doped tin oxide (FTO); conductive polymers such as poly polystyrene sulfonate (PEDOT); and combinations thereof. Preferably, the NIR absorber is a non-stoichiometric inorganic compound. Preferably, the composition comprises from 0.05 to 5 %, such as from 0.05 to 4 % and most preferably, from 0.05 to 3 % of an NIR absorber based on the total solid weight of the composition.

The composition according to the first aspect of the present invention may further comprise a curable compound. Suitable curable compounds will be well known to a person skilled in the art. Examples of suitable curable compounds include, but are not limited to: any commercially available monomers, oligomers, monomer and oligomer mixtures, or photoinitiators. The curable compound may be present in the composition in any suitable amount.

The composition according to the first aspect of the present invention may further comprise an additive or combination of additives. Suitable additives will be well known to a person skilled in the art. Examples of suitable additives include, but are not limited to the following: polymers; light or energy absorbing agents; UV absorbers; surfactants; wetting agents; drying promoters; colourants such as pigments; tinting agents; fluorescent agents; plasticisers; optical brighteners; oxidising or reducing agents; stabilisers; light stabilising agents such as hindered amines; rheology modifiers such as thickening or thinning agents; humectants; adhesion promotors; acid or base scavenging agents; retarders; defoamers; antifoaming agents; and combinations thereof. Preferably, the composition comprises 0.1 to 7 %, such as from 0.1 to 5%, or even from 0.1 to 3 % of additives based on the total solid weight of the composition.

The composition according to the first aspect of the present invention may further comprise a solvent. The composition may comprise a single solvent or a mixture of solvents. The solvent may comprise water, an organic solvent, a mixture of water and an organic solvent, or a mixture of organic solvents. Suitable organic solvents include, but are not limited to the following: alcohols such as ethanol, n-propanol, isopropanol and n-butanol; esters such as ethyl acetate, butyl acetate, and n-hexyl acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and solvent naphtha 100, 150, 200; ketones such as acetone, cyclohexanone, methylisobutyl ketone, and methyl ethyl ketone; glycols such as butyl glycol; glycol ethers such as methoxy propanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether; and combinations thereof. Preferably, the solvent is present in the composition in amounts of from 15 to 70 %, such as from 15 to 60 %, or even from 20 to 55 %.

The composition according to the first aspect of the present invention preferably comprises, in addition to the activatable component and two additional components and optional acid- or base-generating agent(s), a binder, an additive or combination of additives, and a solvent or combination of solvents. If near infrared is to be used to provide the applied transition stimulus or activation temperature, an NIR absorber is preferably present in the composition.

The composition according to the first aspect of the present invention may have a viscosity of from 14 to 120 Zahn seconds (efflux time), suitably measured using a Zahn cup #2 viscosity measurement device at a temperature of 16 to 30 °C. It will be appreciated that the viscosity of the composition is dependent upon a number of factors, including the number, type and amount of the components present in the composition, in addition to the printing application and desired coat weight of the composition when applied on a substrate.

It will be appreciated that the composition according to the first aspect of the present invention may be formed through the combination of formulations containing the different components of the composition, for example the activatable component and each of the two additional components may be in separate formulations, the formulations being combined together to form the composition according to the first aspect of the present invention. It will be further appreciated that the formulations comprise components such as binders, solvents and additives.

It will be appreciated that a composition comprising an activatable component and two additional components enables the production of a broad range of colours in the formation of an image. The different applied transition stimulus, additional applied stimulus, additional temperature, activation temperature can be applied in different combinations at particular localised positions, enabling the formation of many different colours. The invention thus enables the formation of desired single- and multi-coloured images with a broad colour gamut.

The composition according to the first aspect of the present invention may be applied to or incorporated within any suitable substrate. It will be appreciated by a skilled person that the components of a composition will likely vary depending on the substrate to which the composition is to be applied or incorporated within.

Thus, according to a second aspect of the present invention, there is provided a substrate comprising the composition according to the first aspect of the present invention applied to or incorporated within.

Examples of suitable substrates to which the composition may be applied, include, but are not limited to: polymers and recycled polymer materials such as polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), orientated polypropylene (OPP), biaxially orientated polypropylene (BOPP), cast polypropylene (CPP), polyamide (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; cellulose; glass; plastic; metal and metal foils; textiles; paper; corrugated paperboard, cardboard, and equivalent recycled analogues, or combinations thereof; ceramics; foodstuffs and pharmaceutical preparations; or combinations thereof, e.g. polymer lined paper. The polymer and recycled polymer materials may be in the form of polymer film substrates. Examples of suitable substrates within which the composition may be incorporated include, but are not limited to: polymers and recycled polymer materials such as polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), orientated polypropylene (OPP), biaxially orientated polypropylene (BOPP), cast polypropylene (CPP), polyamide (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; and any thermoplastic material such as plastic; or combinations thereof. The polymer and recycled polymer materials may be in the form of polymer film substrates.

It will be appreciated by a skilled person that the substrate to which the composition has been applied to or incorporated within may itself be applied to a further substrate. Examples of further substrates include, but are not limited to the following: polymers and recycled polymer materials such as polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), orientated polypropylene (OPP), biaxially orientated polypropylene (BOPP), cast polypropylene (CPP), polyamide (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; cellulose; glass; plastic; metal and metal foils; textiles; paper; corrugated paperboard, cardboard, and equivalent recycled analogues, or combinations thereof; ceramics; foodstuffs and pharmaceutical preparations; or combinations thereof, e.g. polymer lined paper. The polymers and recycled polymer materials may be in the form of polymer film substrates.

The composition according to the first aspect of the present invention, or substrate according to the second aspect of the present invention to which the composition has been applied to or incorporated within, may be suitable for end use as labels (adhesive and wraparound) and/or in, for example, fast-moving consumer goods; packaging such as disposable packaging including food and hot or cold beverage containers; hygiene and personal care product packaging such as shampoo bottles; cosmetic product packaging; medical and diagnostic devices and associated packaging; and outdoor products such as signage.

Preferably, the substrate comprises an additional adhesive layer. It will be appreciated that this additional adhesive layer is operable to apply the substrate to a further substrate or any other material and is therefore on an exterior surface of the substrate. The adhesive layer may cover all, substantially all, or part of the surface area of an exterior surface of the substrate. When the composition is applied to the substrate, the additional adhesive layer is preferably on an exterior surface of the substrate other than that to which the composition is applied.

Preferably, the composition according to the first aspect of the present invention is applied on a substrate.

Thus, according to a third aspect of the present invention, there is provided a method of forming a substrate comprising applying to or incorporating within the substrate the composition according to the first aspect of the present invention.

The composition may be applied to the substrate by any suitable method. Methods of applying the composition to a substrate will be well known to a person skilled in the art. Suitable application methods include, but are not limited to the following: flexographic printing, gravure printing, screen printing, offset printing and meyer bar coating. The composition may be applied to all, substantially all or part of the surface area of an exterior surface of the substrate.

The composition may be applied on the substrate to any suitable coat weight dependent upon both the substrate to which the composition is applied and the application method. Preferably, the composition is applied to a coat weight of from 0.1 to 50 gsm (grams per square metre), more preferably from 0.1 to 25 gsm and most preferably, 0.1 to 15 gsm. This coat weight is per individual layer of the composition that is applied to the substrate.

The coat weight may be measured by any suitable method. Suitable measuring methods will be well known to those skilled in the art. Preferably, the coat weight is measured by weighing the same area of substrate with and without the composition applied thereto, and comparing the two weights.

The composition may be applied to the substrate as a single layer or as part of a multi-layer system. The composition may be applied to the substrate as an undercoat or an overcoat, on top of a primer or as a primer layer. The composition may be applied to the substrate once or multiple times. The composition may be applied to at least part or all of an exterior surface of the substrate.

The composition may be applied to the substrate as a single layer or as part of a multi-layer system. The composition may be applied to the substrate as an undercoat or an overcoat, on top of a primer or as a primer layer. The composition may be applied to the substrate once or multiple times. The composition may be applied to at least part or all of an exterior surface of the substrate. The composition according to the present invention may be incorporated within the substrate by any suitable method. Methods of incorporating the composition within a substrate will be well known to a person skilled in the art. Suitable incorporation methods include, but are not limited to: extrusion methods including melt extrusion; injection molding; blow molding; compression molding; film insert molding; gas assisted molding; rotational molding; structural foam molding; thermoforming; and combinations thereof.

It will be appreciated by a skilled person that the composition may be incorporated within the substrate on its own or as part of a solid and/or liquid masterbatch. The composition may be incorporated within a substrate to any suitable weight percentage of the total solid weight of the substrate. Preferably, the substrate comprises 0.001 to 50 % of the composition incorporated within, based on the total solid weight of the substrate. More preferably, the substrate comprises 0.002 to 30 % of the composition incorporated within, based on the total solid weight of the substrate. Most preferably, the substrate comprises 0.003 to 20 % of the composition incorporated within, based on the total solid weight of the substrate.

Preferably, the composition according to the first aspect of the present invention is applied to the substrate. The application to, or incorporation of the composition within the substrate enables an image to be formed on or within the substrate. It will be appreciated that the composition enables a single-or multi-coloured image to be formed on or within the substrate.

Thus, according to a fourth aspect of the present invention, there is provided a method of forming colour on or within a substrate comprising the composition according to the first aspect of the present invention applied to or incorporated within, the method comprising applying to the composition on or within the substrate the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components of the composition.

According to a fifth aspect of the present invention, there is provided a method of forming an image on or within a substrate comprising the composition according to the first aspect of the present invention applied to or incorporated within, the method comprising applying to the composition on or within the substrate the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components at of the composition, and thereby create an image on or within the substrate.

It will be understood by a skilled person that the applied transition stimulus and activation temperature and each of the additional applied stimulus or additional applied temperature may be applied to the composition such that the non- coloured state and/or coloured state of the activatable component and each of the two additional components are present at different localised positions of the composition to create an image. The coloured states of the activatable component and each of the additional components may be selectively developed at localised positions. Suitable means for applying the applied transition stimulus, activation temperature, and each of the additional applied stimulus or additional temperature are as discussed above. It will be further understood by a skilled person that the application of the applied transition stimulus, activation temperature and each of the additional applied stimulus or additional temperature to the composition, will be conducted in the appropriate order required to form the desired image. This can facilitate the formation of a multi-coloured image.

It will be understood by a skilled person that more than one of the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures may be applied at the same localised position. For example, in order to form a colour resulting from the mixing of two colours (i.e. the mixing of the colours of a coloured state of the activatable component and a coloured state of one of the two additional components of a different colour) the applied transition stimulus and activation temperature, and each of the additional applied stimuli or additional temperatures may be applied to that particular localised position of the composition. It will be appreciated by a skilled person that the relationship between the activation temperature and additional temperatures will vary dependent upon the colours required in the image that is to be formed. It will be appreciated by a skilled person that the relationship between the wavelengths of the applied transition stimulus and additional applied stimuli will vary dependent upon the colours required in the image that is to be formed so as to facilitate formation of the desired image.

Optionally, a separate conductive source of temperature may also be provided to the composition before, during or after the formation of the image. Conductive sources of temperature include, but are not limited to the following: sources of steam and hot air, lamps, heat tunnels, LED(s), thermal print heads, hotplates, thermal conductors, hot liquids, and heated substrates.

According to an sixth aspect of the present invention, there is provided a use of the composition according to the first aspect of the present invention in the formation of colour on or within a substrate. According to a seventh aspect of the present invention, there is provided a use of the composition according to the first aspect of the present invention in the formation of an image on or within a substrate.

According to an eighth aspect of the present invention, there is provided a substrate having applied thereon a plurality of discrete layers, wherein the plurality of discrete layers comprise:

(a) an activatable component capable of transitioning from a non-coloured state to a coloured state, the transition being effected by the application of an applied transition stimulus, wherein the activatable component requires activation to allow transitioning to occur, where said activation occurs by application of an activation temperature; and

(b) two additional components each capable of transitioning from a non- coloured state to a coloured state, the transition being effected by the application of an additional applied stimulus or an additional temperature; wherein, if formed, the coloured states of the activatable component and each of the two additional components are different in colour, and the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers applied on the substrate.

In the eight aspect of the present invention, the activatable component and two additional components are as defined above throughout the first to seventh aspects of the present invention. In addition, the applied transition stimulus, activation temperature, additional applied stimulus and additional temperature are as defined above throughout the first to seventh aspects of the present invention. It will be further appreciated that the substrate according to the eighth aspect of the present invention is based upon the substrate according to the second aspect of the present invention, the substrate according to the second aspect of the present invention having a composition layer applied to or incorporated within, and the substrate according to the eighth aspect of the present invention having a plurality of discrete layers applied thereon. It will be appreciated that, as defined above for the first aspect of the present invention, the two additional components must be components selected from groups (b1 ) to (b5) as defined above. The two additional components independently selected from groups (b1 ) to (b5) are different. By different is meant that the two additional components are selected either from different groups of (b1 ) to (b5) as defined below, or are selected from the same group (b1 ) to (b5), but are selected so as to be different compounds in that group, e.g. two different leuco dyes. Preferably, the two additional components are independently selected from different groups (b1 ) to (b5)

It will further be appreciated that, as defined above for the composition of the first aspect of the present invention, in one embodiment, the plurality of discrete layers do not comprise a combination of an activatable component and only components of groups (b3) and (b5).

It will also be appreciated that by the activatable component and at least one of the two additional components being present in different layers of the plurality of discrete layers is meant that:

(a) there may be a first discrete layer comprising the activatable component, and a second different discrete layer comprising an additional component, and the second additional component is present in either of the first or second layers; or

(b) there may be a first discrete layer comprising the activatable component, a second different discrete layer comprising an additional component, and a third different discrete layer (different to the first and second layers) comprising a different additional component.

These three layers can be in any order on the substrate.

By different additional components is meant that the two additional components are selected either from different groups of (b1 ) to (b5) as defined above, or are selected from the same group (b1 ) to (b5), but are selected so as to be different compounds in that group, e.g. two different leuco dyes. Preferably, the two additional components are independently selected from different groups (b1 ) to (b5). Preferably, the activatable component and at least one of the two additional components are present in different layers of the plurality of discrete layers, i.e. (b) there may be a first discrete layer comprising the activatable component, a second different discrete layer comprising an additional component, and a third different discrete layer (different to the first and second layers) comprising a different additional component.

Preferably, the plurality of discrete layers comprises an activatable component, a keto acid compound and an oxyanion of a multivalent metal. Preferably, the three components are each in a different discrete layer.

The plurality of discrete layers may comprise one or more additional layers. Suitable additional layers may be selected from, but not limited to: thermal insulating layers; polymer layers; radiation blocking layers such as layers comprising UV absorbing components or layers comprising UV absorbing components; primers; adhesion promoting layers; quenching layers; layers comprising hindered amine light stabilisers; overprint varnish layers; barrier layers; diffusion barrier layers; and combinations thereof.

It will be further appreciated that the discrete layer comprising the activatable component is preferably formed of a composition applied to the substrate. In addition, each of the different discrete layers comprising an additional component is preferably formed of a composition applied to the substrate. When the three different discrete layers comprising activatable component and the two additional components are formed from such compositions, the activatable component and each of the additional components may be present in those individual compositions in any suitable amount, preferably from 5 to 60% of the total solid weight of the composition, or even from 5 to 50%, or from 5 to 35% of the total solid weight of the composition, or even from 5 to 15% of the total solid weight of the composition. Such compositions are formulated with other components such as NIR absorbers, binders, solvents and additives as defined above for the composition according to the first aspect of the present invention. It will be further be appreciated that any acid- or base-generating agent associated with an additional component will be as defined above in relation to the first aspect of the present invention, and will be present in the same layer as the additional component to which it relates, i.e. will be present in the same composition forming the discrete layer comprising the additional component in amounts as defined above in relation to the first aspect of the present invention.

It will be appreciated by a skilled person that if the plurality of discrete layers comprises one or more additional layers and these one or more additional layers are positioned between the discrete layer comprising the activatable component and each of the different discrete layers comprising an additional component, the one or more additional layers mean that the applied transition stimulus and activation temperature and additional applied stimulus or additional temperature can be applied to the substrate from both sides in order to form multi-coloured images, the two sides being defined by the one or more additional layers separating the layer comprising the activatable component from the layers comprising the two additional components.

The plurality of discrete layers may have any suitable overall coat weight. Preferably, the plurality of discrete layers individually have a coat weight as set out above in relation to the composition according to the first aspect of the present invention. Further, preferably the plurality of discrete layers have an overall coat weight (encompassing all layers) of less than 100 gsm (grams per square metre), more preferably less than 50 gsm, and most preferably less than 30 gsmlt will be appreciated by a skilled person that the overall coat weight of the plurality of discrete layers will be dependent upon the layer formation and the substrate.

The substrate according to the eighth aspect of the present invention may be suitable for end use as labels (adhesive and wraparound) and/or, in fast-moving consumer goods; packaging such as disposable packaging including food and hot or cold beverage containers; hygiene and personal care product packaging such as shampoo bottles; cosmetic product packaging; medical and diagnostic devices and associated packaging; and outdoor products such as signage.

The plurality of discrete layers may be applied to any suitable substrate. It will be appreciated by a skilled person that the layer structure of the plurality of discrete layers may vary depending on the substrate to which it is to be applied. The substrates to which the plurality of discrete layers may be applied are as described above in relation to the substrate according to the second aspect of the present invention.

Examples of suitable substrates to which the plurality of discrete layers may be applied to, include, but are not limited to: polymers and recycled polymer materials such as polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), orientated polypropylene (OPP), biaxially orientated polypropylene (BOPP), cast polypropylene (CPP), polyamide (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; cellulose; glass; plastic; metal and metal foils; textiles; paper; corrugated paperboard, cardboard, and equivalent recycled analogues, or combinations thereof; ceramics; foodstuffs and pharmaceutical preparations; or combinations thereof, e.g. polymer lined paper. The polymers and recycled polymer materials may be in the form of polymer film substrates.

Preferably, the substrate to which the plurality of discrete layers are applied is a polymer film substrate. Preferably, the substrate is colourless (i.e. transparent or translucent), off-white or white. Preferably, the substrate is colourless, and is a polymer film substrate.

It will be appreciated by a skilled person that the substrate to which the plurality of discrete layers has been applied to may itself be applied to a further substrate. Examples of further substrates include, but are not limited to the following: polymers and recycled polymer materials such as polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), orientated polypropylene (OPP), biaxially orientated polypropylene (BOPP), cast polypropylene (CPP), polyamide (PA) such as nylon, polyvinyl chloride (PVC), or combinations thereof; cellulose; glass; plastic; metal and metal foils; textiles; paper; corrugated paperboard, cardboard, and equivalent recycled analogues, or combinations thereof; ceramics; foodstuffs and pharmaceutical preparations; or combinations thereof, e.g. polymer lined paper. The polymers and recycled polymer materials may be in the form of polymer film substrates. Preferably, the substrate to which the plurality of discrete layers are applied comprises an additional adhesive layer. It will be appreciated that this additional adhesive layer is operable to apply the substrate to a further substrate or any other material and is therefore on an exterior surface of the substrate. The adhesive layer may cover all, substantially all, or part of the surface area of an exterior surface of the substrate.

Thus, according to a ninth aspect of the present invention there is provided a method of forming a substrate according to the eighth aspect of the present invention, the method comprising applying to a substrate the plurality of discrete layers.

It will be appreciated that the method of forming the substrate according to the ninth aspect of the present invention is as defined above for the third aspect of the present invention.

The plurality of discrete layers may be applied to the substrate by any suitable method. Methods of applying the plurality of discrete layers to a substrate will be well known to a person skilled in the art. Suitable application methods include, but are not limited to the following: flexographic printing, gravure printing, screen printing, offset printing and meyer bar coating. The plurality of discrete layers may be applied to all, substantially all or part of the surface area of the substrate. The plurality of discrete layers is applied to the substrate layer by layer in the required order. The application of the plurality of discrete layers to the substrate enables an image to be formed on the substrate.

Thus, according to a tenth aspect of the present invention, there is provided a method of forming colour on a substrate according to the eighth aspect of the present invention, the method comprising applying to the substrate, the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components.

According to an eleventh aspect of the present invention, there is provided a method of forming an image on a substrate according to the eighth aspect of the present invention, the method comprising applying to the substrate, the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures, as required to develop the coloured states of the activatable component and two additional components, and thereby forming an image on the substrate.

It will be appreciated that the methods of forming colour and an image according to the tenth and eleventh aspects of the present invention require similar considerations to those defined above for the fourth and fifth aspects of the present invention.

The application of the applied transition stimulus and activation temperature and each of the additional applied stimuli or additional temperatures to the substrate may be such that the non-coloured states and/or coloured states of the activatable component and two additional components are formed at different localised positions to create an image. Their application will be conducted in the appropriate order required to selectively form the non-coloured and/or coloured states of the activatable component and two additional components at localised positions. The coloured states of the activatable component and the two additional components may be selectively developed at localised positions. Multi-coloured images can be formed. Suitable means for applying the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures are as defined above.

It will be further understood by a skilled person that more than one of the applied transition stimulus, activation temperature and each of the additional applied stimuli or additional temperatures may be applied at the same localised position. For example, in order to form a colour resulting from the mixing of two colours (i.e. the mixing of colours of a coloured state of the activatable component and a coloured state of one of the additional components of a different colour) the applied transition stimulus, activation temperature and at least one of the additional applied stimuli or additional temperatures will be applied to that particular localised position. It will be appreciated by a skilled person that the relationship between the activation temperature and the additional temperatures will vary dependent upon the colours required in the image that is to be formed. It will be appreciated by a skilled person that the relationship between the wavelengths of the applied transition stimulus and the additional applied stimuli will vary dependent upon the colours required in the image that is to be formed so as to facilitate the formation of the desired image.

Optionally, a separate conductive source of temperature may be provided to the composition before, during or after the formation of the image. Conductive sources include, but are not limited to the following: sources of steam and hot air, lamps, heat tunnels, LED(s), thermal print heads, hotplates, thermal conductors, hot liquids and heated substrates.

It will be appreciated by a skilled person that the radiation applied to the compositions or substrates disclosed herein, whether by a laser source(s) or flood illumination, is applied using an apparatus suitable for such purpose, i.e. suitable for calculating the radiation required relating to the different stimuli and temperatures required to produce a desired image and applying it to the composition or substrate. It will be appreciated that the apparatus will be programmed to effect the application of the different stimuli and temperatures to the compositions or substrates in the required order and facilitate the formation of an image.

Chemical Definitions

The term "Ci-i 8 alkyl" demotes a straight or branched saturated alkyl group having from 1 to 18 carbon atoms; optionally "C M S alkyl" groups can contain some degree of unsaturation (partial unsaturation) i.e. may contain one or more alkene/alkenyl moiety(s). For parts of the range C M S alkyl, all sub-groups thereof are contemplated, such as C M O alkyl, C 5-i 5 alkyl, C 5-i 0 alkyl, and Ci -6 alkyl. Examples of said Ci -4 alkyl groups include methyl, ethyl, n-propyl, iso- propyl, n-butyl, iso-butyl, sec-butyl, and tert-butyl. The alkyl groups may be optionally substituted with one or more functional groups, including C M S alkyl groups, "C 6- 12 aryl", and "C M S alkoxy", halogen, and "C 3-i8 cycloalkyl".

The term "C 6- 12 aryl" denotes a monocyclic or polycyclic conjugated unsaturated ring system having from 6 to 12 carbon atoms. For parts of the range C 6- 12 aryl, all sub-groups thereof are contemplated, such as C 6-i o aryl, Ci 0- 12 aryl, and C 6 -s aryl. An aryl group includes condensed ring groups such as monocyclic ring groups, or bicyclic ring groups. Examples of C 6- 12 aryl groups include phenyl, biphenyl, indenyl, naphthyl or azulenyl. Condensed rings such as indan and tetrahydro naphthalene are also included in the C 6- 12 aryl group. The aryl groups may be optionally substituted with other functional groups. The aryl groups may be optionally substituted with one or more functional groups, including C M S alkyl groups, halogen, and "C M S alkoxy". The aryl groups may be substituted with these substituents at a single position on their unsaturated ring system, or may be substituted with these substituents at multiple positions on their unsaturated ring system.

The term "C M S alkoxy" denotes a straight of branched C M S alkyl group which is attached to the remainder of the molecule through an oxygen atom. For parts of the range C M S alkoxy, all sub-groups thereof are contemplated such as C M O alkoxy, C 5-i 5 alkoxy, C 5-i0 alkoxy, and Ci -6 alkoxy. Examples of said Ci -4 alkoxy groups include methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, sec-butoxy, and tert-butoxy. The alkoxy groups may be optionally substituted with other functional groups. The alkoxy groups may be optionally substituted with one or more functional groups, including C M S alkyl groups, "C 6- 12 aryl", and "Ci-is alkoxy", halogen, and "C 3-i8 cycloalkyl".

The term "C 3-i8 cycloalkyl" denotes a non-aromatic, saturated or partially saturated (i.e. may contain one or more alkene or alkenyl moiety(s)) monocyclic ring system having from 3 to 18 carbon atoms. For parts of the range C 3-i 8 cycloalkyl, all sub-groups thereof are contemplated, such as C 3-8 cycloalkyl, C 5-i 5 cycloalkyl, and C 5-i0 cycloalkyl. Examples of suitable C 3-i0 cycloalkyls include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. The cycloalkyl groups may be optionally substituted with other functional groups. The cycloalkyl groups may be optionally substituted with one or more functional groups, including Ci -20 alkyl groups, "C 5-2 o aryl", "Ci -20 alkoxy", "hydroxylCi -2 o alkoxy" and "C 3-i 8 cycloalkyl". The terms“unsaturated” and“partially saturated” refer to rings wherein the ring structure(s) contains atoms sharing more than one valence bond i.e. the ring contains at least one multiple bond e.g. a C=C, CºC or N=C bond. The term “fully saturated” refers to rings where there are no multiple bonds between ring atoms.

“Optional” or “optionally” means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not.

"Halogen" refers to fluorine, chlorine, bromine or iodine.

The term "heterocycle" and "heterocyclic ring" denotes a non-aromatic, saturated or partially saturated monocyclic or polycylic ring system having from 4 to 18 ring atoms in which one or more of the ring atoms is not carbon, e.g. nitrogen, sulphur or oxygen. The said ring system may be attached to the rest of the molecule through either a heteroatom or a carbon atom of the ring system. Examples of heterocyclic groups include but are not limited to: piperidinyl, morpholinyl, homomorpholinyl, azepanyl, piperazinyl, oxo-piperazinyl, diazepinyl, tetrahydropyridinyl, tetrahydropyranyl, pyrrolidinyl, tetrahydrofuranyl and dihydropyrrolyl.

The terms “heteroaryl” and “heteroaromatic ring” denote a monocyclic or polycyclic hetero-aromatic group comprising 5 to 18 atoms in which one or more of the atoms are other than carbon, such as nitrogen, phosphorus, sulphur or oxygen. The said hetero-aromatic ring may be attached to the rest of the molecule through either a heteroatom or a carbon atom of the ring system. Examples of heteroaryl groups include but are not limited to furyl, pyrrolyl, thienyl, oxazolyl, isoxazolyl, oxadiazolyl, imidazolyl, oxatriazoly, thiazolyl, isothiazolyl, tetrazolyl, pyrazolyl, pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl and thiadiazolyl. In some embodiments, the heteroaryl group contains at least one ring nitrogen atom. The nitrogen atoms in the heteroaryl groups can be basic, as in the case of an imidazole or pyridine, or essentially non-basic as in the case of an indole or pyrrole nitrogen. In general the number of basic nitrogen atoms present in the heteroaryl group, including any amino group substituents of the ring, will be less than five.

The term“cyclic amino group” refers to a non-aromatic, fully saturated or partially unsaturated monocyclic ring system having from 4 to 18 ring atoms in which one of the ring atoms is nitrogen and the group is attached to the rest of the molecule via this nitrogen atom. In such cyclic amino groups, one or more of the remaining ring atoms may be other than carbon, such as nitrogen, sulphur or oxygen. Examples of such cyclic amino groups include piperidine (1-piperidinyl), pyrrolidine (1- pyrrolidinyl), pyrrolidone, morpholine or piperazine.

By "secondary amino group" is meant an amine group formed by replacement of two of the hydrogen atoms in ammonia by groups or atoms other than the hydrogen atoms, the group being attached to the rest of the molecule by the bond other than the two joining the two groups or atoms replacing the hydrogen atoms to the nitrogen atom.

All of the features contained herein may be combined with any of the above aspects and in any combination.

For a better understanding of the present invention, and to show embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following experimental data.

Examples

General Procedure for the Synthesis of an Additional Component: (b1 ) A Pyrazole (Thio)Semicarbazone Compound of Formula (III)

Step 1 : Synthesis of a pyrazaole ring

A hydrazine and an ethyl-3-oxo-3-propanoate are refluxed together releasing ethanol and water, and forming a pyrazalone ring product having substituents A and B on the ring. The product is purified by precipitation or recrystallization from an appropriate solvent.

Step 2: Addition of a reactive ketone substituent

The pyrazalone ring product from step 1 is reacted with an acyl chloride in the presence of calcium hydroxide under reflux. The reactive ketone product is purified by either precipitation or recrystallization from an appropriate solvent.

Step 3: Formation of the semicarbazide

The condensation of the reactive ketone product from step with a hydrazine carboxamide in the presence of an acetic acid catalyst produces the final reaction product. The product is then purified by precipitation or recrystallization from an appropriate solvent.

Specific Synthesis of an Additional Component: (b1) A Pyrazole

(Thio)Semicarbazone Compound of Formula (III): (E)-2-((5-hydroxy-1 ,3-diphenyl- 1 H-pyrazol-4-yl)(4-(trifluoromethyl)phenyl)methylene-N-phenyl hydrazine-1- carboxamide For (E)-2-((5-hydroxy-1 ,3-diphenyl-1 H-pyrazol-4-yl)(4-

(trifluoromethyl)phenyl)methylene-N-phenylhydrazine-1-car boxamide: A = phenyl, B

= phenyl, C = phenyl substituted with CF 3 , and D = phenyl.

Step One: Synthesis of 1 ,3-diphenyl-5-pyrazalone (DPP) 1. A 3 neck round bottom flask (rbf) fitted with a thermometer and stirrer bar is charged with Toluene (50 ml_, colourless liquid).

2. Ethyl 3-oxo-3-phenylpropanoate (100 g, 0.52 mmol, colourless liquid) is added to the round bottom flask.

3. Phenylhydrazine (56 g, 0.51 mmol, yellow liquid) is added to the round bottom flask and the mixture is stirred resulting in a pale-yellow solution. 50 ml of additional toluene is used to rinse any excess phenylhydrazine into the reaction.

4. A dean stark trap is fitted to the flask with a reflux condenser attached.

5. A heating block is used to heat the reaction solution to 110 °C. 6. The dean stark apparatus is used to remove water/ethanol and assess when the reaction has gone to completion (TLC may also be used to assess progress of reaction eluting with DCM/Heptane 4:1 ).

7. The reaction mixture is allowed to cool with stirring to avoid the formation of large clumps of product. 8. Once the reaction mixture is cool enough to handle, it is poured into a large beaker and any large product clumps are broken up with a spatula.

9. Heptane (-100 ml_) is added to the beaker and a large spatula is used to break up all the clumps rending the material into a relatively free flowing crystalline powder. 10. An additional 1.4 L of heptane is added and the product slurried overnight. 1 1. The pale-yellow solids are vacuum filtered and dried under vacuum (108.4 g, 88 %).

Step Two: Synthesis of (5-hvdroxy-1 ,3-diphenyl-1 H-pyrazol-4-yl)(4-

(trifluoromethvDphenvDmethanone Bn-DPP)

1. DPP (25.75 g, 109.0 mmol) is weighed and placed in a 3-neck round bottom flask (rbf) fitted with a stirrer, thermometer and dropping funnel.

2. 1 ,4-dioxane (300 ml_) is added and the mixture stirred until the DPP is

dissolved, giving a pale-yellow solution.

3. Calcium hydroxide (24.22 g, 326.9 mmol) is added and the suspension

stirred.

4. 4-(trifluoromethyl)benzoyl chloride (25.00 g, 1 19.9 mmol) is weighed into a beaker and dissolved in 1 ,4-dioxane (100 ml_).

5. The 4-(trifluoromethyl)benzoyl chloride solution is transferred to the dropping funnel. 6. The reaction suspension is cooled using a cold water-bath.

7. The 4-(trifluoromethyl)benzoyl chloride solution is added dropwise over 40 minutes ensuring that the reaction mixture does not exceed 50 °C.

8. The dropping funnel is replaced by a reflux condenser and the reaction

mixture is heated to reflux and followed by TLC (DCM 20% EtOAc). 9. The reaction is stirred for 2 hours.

10. The reaction solution is allowed to cool back to 50 °C.

1 1. The reaction solution is poured into aqueous HCI (2 M,1.1 L, 2.18 mol) with strong stirring causing a pale-yellow precipitate to form which rapidly clumps and turns brown. 12. The suspension is stirred vigorously for approximately 2 hours. 13. The precipitate is vacuum filtered on paper and partially dried by suction giving a sandy brown solid.

14. The brown solids are transferred to a large beaker and slurried in hot I PA for around 3 hours, the solvent is allowed to cool while still slurrying. 15. The yellow solids are then vacuum filtered on paper and dried by suction for around 1 hour.

16. The yellow solids are transferred to a drying dish and dried in a vacuum oven (30 °C) over night (36.60 g, 82.24 %).

Step Three: Synthesis of (E)-2-((5-hvdroxy-1 ,3-diphenyl-1 H-pyrazol-4-yl)(4- (trifluoromethyl)phenyl)methylene-N-phenylhydrazine-1 -carboxamide

1. CF 3 -Bn-DPP (20.08 g, 49.17 mmol) is weighed and placed into a 3-neck round bottom flask (rbf) fitted with a stirrer bar, thermometer and condenser.

2. 4-phenylsemicarbazide (8.18 g, 54.09 mmol) is weighed and placed into the round bottom flask. 3. Ethanol (200 ml_) is added to the reaction vessel and the mixture stirred.

4. Glacial acetic acid (0.1 M in ethanol, 5 ml_, 0.49 mmol) is added to the

reaction mixture.

5. The reaction mixture is heated to reflux (80 °C) and followed by TLC (DCM 40% ethylacetate). 6. The reaction kis refluxed for 6 hours and then left to cool and stand over the weekend.

7. Over the weekend a large quantity of white precipitate formed, this is vacuum filtered on paper, washed with I PA and dried by suction for an hour.

8. The solids are placed in a beaker and dried under vacuum overnight (30 °C) giving an off-white fluffy powder (22.35 g, 83.9 %). General Procedure for the Synthesis of an Additional Component: (b4) A Compound of Formula (VIII) or (IX) Formed From a Salicylic Aldehyde or Salicylic Ketone Compound 1. The selected 2-hydroxyarylcarbonyl (aldehyde or ketone) (2.1 molar equivalent) is dissolved/suspended in ethanol (0.3 to 1.2 molar equivalent) in a 3-neck round bottom flask fitted with a dropping funnel, stirrer bar and thermometer.

2. A solution of hydrazine hydrate (35% or 79% w/v, 1.0 molar equivalent) in ethanol is prepared and placed in the dropping funnel.

3. The hydrazine hydrate solution is added with stirring over the course of 5 to 20 minutes to the solution of the 2-hydroxyarylcarbonyl. This addition may result in a small exotherm.

4. The dropping funnel is replaced with a condenser and the reaction mixture brought to reflux (80 °C).

5. The reaction mixture is refluxed with stirring for 5 hours and then left to cool overnight.

6. Once cooled, any precipitate which is formed is vacuum filtered on paper and washed with additional ethanol and optionally, additional water, to ensure the complete removal of any remaining hydrazine hydrate.

7. The collected solids may be vacuum filtered on paper and dried in a vacuum oven overnight; or the collected solids may be dissolved with heating in solvent and then precipitated by addition of further solvent, and the resulting solids vacuum filtered on paper and dried in a vacuum oven overnight; or the collected solids may be recrystallised from hot ethanol, and vacuum filtered on sintered glass and left to air dry. It will be appreciated that the selection of the methodology in step 7 will be dependent upon the properties of the specific solids formed.

Specific Synthesis of an Additional Component: (b4) A Compound of Formula (VIII) Formed From a Salicylic Aldehyde or Salicylic Ketone Compound: 2,2'- ((1 E,1 'E)-hvdrazine-1 ,2-diylidenebis(methaneylylidene))diphenol

For 2,2'-((1 E,1 'E)-hydrazine-1 ,2-diylidenebis(methaneylylidene))diphenol: Xi a , X 2a , X3 a , X 4a , Xi b , X2 b , X3 b and X 4b are C, R 1 and R 2 are hydrogen, and R 3 and R 4 are hydrogen.

1. A solution of salicylaldehyde (45 g, 0.37 mol) in ethanol (100 ml) was prepared in a 3-neck round bottom flask (rbf) fitted with a dropping funnel, stirrer bar and thermometer.

2. A solution of hydrazine hydrate (35 % w/v, 15.8 ml, 0.17 mol) in ethanol (50 ml) is prepared and placed in the dropping funnel.

3. The hydrazine hydrate solution is added with stirring over the course of 20 minutes to the salicylaldehyde solution resulting in a small exotherm (initial temperature 20 °C, final temperature 50 °C).

4. During the addition, the suspension thickens to the point where stirring is ineffective, therefore three additional portions of ethanol (50 ml each) are added to the flask during the addition to maintain stirring of the suspension. 5. The dropping funnel is replaced with a condenser and the reaction brought to reflux (80 °C).

6. The reaction is refluxed with stirring for 5 hours and then left to cool overnight

7. The cooled crystalline yellow precipitate that formed is vacuum filtered on paper and washed with additional ethanol. 8. The collected solids are recrystallised from hot ethanol yielding a pale yellow crystalline solid. 9. The resulting solids are vacuum filtered on sintered glass and left to air dry to yield a pale-yellow crystalline product (40.4 g, 96 %).

Synthesis of an Additional Component: (b2) A Keto Acid Compound of Formula iY)

The keto acid compounds of formula (V) can be purchased from Chameleon Speciality Chemicals Ltd, or formulated according to the following syntheses.

General Procedure for the Synthesis of a Keto Acid Compound of Formula (V)

An amino-phenol (1 equivalent) and anhydride (1 equivalent) are weighed into a round bottom flask fitted with a stirrer bar, thermometer and reflux condenser. The solids are suspended in toluene (0.3 to 2.0 molar solution) and refluxed for 18 hours. The reaction mixture is allowed to cool to room temperature and the solvent removed on a roto-evaporator. The product is isolated by flash column chromatography eluting with a polarity gradient from Heptane/DCM 1 :1 to DCM 20 % Ethyl Acetate. The column fractions are concentrated on a roto-evaporator to ~0.5 L and precipitated by adding the solution to a beaker of stirred Heptane (1 to 2 L). The precipitate is vacuum filtered onto paper, dried by suction for around 10 minutes then transferred to a drying dish and dried in a vacuum oven (20 °C) overnight yielding the product as a pale coloured powder.

Specific Synthesis of a Keto Acid Compound of Formula (V): (2-(4- (dimethylamino)-2-hvdroxybenzoyl)benzoic acid

3-(Dimethylamino)phenol (26.0 g, 190 mmol) and Phthalic anhydride (28.07 g, 189.5 mmol) were weighed into a round bottom flask fitted with a stirrer bar, thermometer and reflux condenser. The solids were suspended in toluene (100 mL) and reflux for 18 hours. The reaction mixture was allowed to cool to room temperature and the solvent removed on a roto-evaporator. The residue was extracted into ethyl acetate (500 mL) with sonication and heating. The mixture was filtered through sintered glass. The filtrate was precipitated by addition of heptane (500 ml_) and the dark solids vacuum filtered onto paper. The solids were dissolved in dichloromethane (300 ml_) and passed through a silica pad eluting with dichloromethane until the filtrate ran clear. The dichloromethane solution was concentrated on a roto-evaporator to ~0.5 L and was precipitated by adding the dichloromethane solution to a beaker of stirred Heptane (1 L). The precipitate was vacuum filtered onto paper, dried by suction for around 10 minutes then transferred to a drying dish and dried in a vacuum oven (20 °C) overnight yielding the product as a beige coloured powder (22.23 g, 77.92 mmol, 41.1 %).

Specific Synthesis of a Keto Acid Compound of Formula (V): (2-(4-

(diethylamino)-2-hvdroxybenzoyl)-5-nitrobenzoic acid

3-(Diethylamino)phenol (21.47 g, 129.9 mmol) and 4-nitro-phthalic anhydride (25.07 g, 129.8 mmol) were weighed into a round bottom flask fitted with a stirrer bar, thermometer and reflux condenser. The solids were suspended in toluene (100 ml_) and reflux for 18 hours. The reaction mixture was allowed to cool to room temperature and the solvent removed on a roto-evaporator. The product was isolated by flash column chromatography eluting with a polarity gradient from Heptane/DCM 1 :1 to DCM 10 % Ethyl Acetate. The column fractions were concentrated on a roto-evaporator to -0.5 L and was precipitated by adding the solution to a beaker of stirred heptane (1 L). The precipitate was vacuum filtered onto paper, dried by suction for around 10 minutes then transferred to a drying dish and dried in a vacuum oven (20 °C) overnight yielding the product as a pale-yellow coloured powder (7.60 g, 21.2 mmol, 16.3 %).

Synthesis of A Keto Acid Compound of Formula (V): (2,3,4,5-tetrachloro-6-(4-

(diethylamino)-2-hvdroxybenzoyl)benzoic acid

3-(Diethylamino)phenol (22.00 g, 131.1 mmol) and tetrachloro-phthalic anhydride (38.06 g, 131.1 mmol) were weighed into a round bottom flask fitted with a stirrer bar, thermometer and reflux condenser. The solids were suspended in toluene (100 ml_) and reflux for 18 hours. The reaction mixture was allowed to cool to room temperature and the solvent removed on a roto-evaporator. The product was isolated by flash column chromatography eluting with a polarity gradient from Heptane/DCM 1 :1 to DCM 10 % ethyl acetate. The column fractions were concentrated on a roto-evaporator to -0.5 L and was precipitated by adding the solution to a beaker of stirred heptane (1 L). The Precipitate was vacuum filtered onto paper, dried by suction for around 10 minutes then transferred to a drying dish and dried in a vacuum oven (20 °C) overnight yielding the product as a yellow coloured powder (15.63 g, 34.65 mmol, 26.02 %).

Synthesis of a Keto Acid Compound of Formula (V): (2,5-bis(4-(diethylamino)-2- hydroxybenzovDterephthalic acid

3-(Diethylamino)phenol (39.3 g, 230 mmol) and Pyromellitic anhydride (25.0 g, 114.6 mmol) were weighed into a round bottom flask fitted with a stirrer bar, thermometer and reflux condenser. The solids were suspended in toluene (400 ml_) and reflux for 18 hours. The reaction mixture was allowed to cool to room temperature and the solvent removed on a roto-evaporator. The product was isolated by flash column chromatography eluting with a polarity gradient from Heptane/DCM 1 :1 to DCM 20 % ethyl acetate. The column fractions were concentrated on a roto-evaporator to ~0.5 L and was precipitated by adding the solution to a beaker of stirred heptane (2 L). The precipitate was vacuum filtered onto paper, dried by suction for around 10 minutes then transferred to a drying dish and dried in a vacuum oven (20 °C) overnight yielding the product as a yellow coloured powder (5.84 g, 10.6 mmol, 9.29 %).

Colour Formation Using the Activatable Components and Two Additional Components of the Present Invention

For each of the examples, unless otherwise stated, the natural state (non- coloured state) of the activatable component or and two additional components is either off-white or white.

For each of the examples, unless otherwise indicated, the 10.6 pm C0 2 laser is set at a speed of 2600 - 5350 /s and at 38% power. The speed or power can be varied to alter the fluence applied by the laser source. Marking speeds within the 2600-5350 mm/s range are 2600, 2975, 3325, 3600, 3850, 4100, 4300, 4750,

5050 and 5350 mm/s.

Example 1

A composition comprising an oxyanion of a multivalent metal (an additional component) is formulated according to Table 1. All amounts are provided in weight percentage (wt%).

Table 1

A composition comprising an a diacetylene compound (an activatable component) is formulated according to Table 4, using the millbase formulations in Tables 2 and 3. All amounts are provided in weight percentage (wt%). Table 2 - Millbase formulation of diacetylene compound

Table 3 - Millbase formulation of NIR absorber

Table 4

A composition comprising a pyrazole (thio)semicarbazone compound of formula (III) (an additional component) was formulated according to Table 5.

Table 5

A layer of the composition comprising an oxyanion of a multivalent metal is applied to a paper substrate using a k2 k-bar applicator. A layer of the composition comprising a diacetylene compound is applied using a k2 k-bar applicator over the layer of the composition comprising an oxyanion of a multivalent metal. A layer of the composition comprising a pyrazole (thio) semicarbazone compound of formula (III) is then applied using a k2 k-bar applicator over the layer of the composition comprising a diacetylene compound. Following application to the substrate, the pyrazole (thio)semicarbazone compound of formula (III), the diacetylene compound and the oxyanion of a multivalent metal are in the non-coloured state.

When a germicidal UV lamp is used to apply UV radiation (additional applied stimulus) to the substrate via flood illumination, the pyrazole (thio)semicarbazone compound of formula (III) transitions from the non-coloured to a pale yellow coloured state, such that a pale yellow colour is displayed on the substrate.

An additional temperature is applied using a 10.6 pm C0 2 laser (38% power) to provide NIR radiation to localised positions of the substrate either prior to or subsequent to the application of the UV radiation. At these localised positions, the oxyanion of a multivalent metal transitions from its non-coloured to a black coloured state. The intensity of the colour formed can be varied by variation of the fluence provided by the C0 2 laser.

It is noted that the additional temperature required to facilitate the transition of the oxyanion of a multivalent metal from the non-coloured to a coloured state is higher than the activation temperature of the diacetylene compound. Accordingly, upon application of the additional temperature required to facilitate the transition of the oxyanion of a multivalent metal from the non-coloured to a coloured state, the activation temperature is reached and the non-coloured state of the diacetylene compound is also‘activated’ at these localised positions. Upon further application of UV radiation (applied transition stimulus) via flood illumination using a germicidal lamp, the diacetylene compound transitions from the activated non-coloured state to a blue coloured state at these localised positions. As the coloured state of the diacetylene compound is formed at the same localised position at which the coloured state of the oxyanion of a multivalent metal has been formed, the final colour displayed at these localised positions is dependent upon the colour of the blue coloured state of the diacetylene compound, and the black coloured state of the oxyanion of a multivalent metal, i.e. the final colour at these localised positions results from the combination of colours of the coloured states of the two components. Accordingly, different blue and black colours can be formed. It is noted that, when formed, the colour of the coloured state of the pyrazole (thio)semicarbazone compound of formula (III) also contributes to the final colour displayed at the localised positions.

A multi-coloured image may therefore be formed displaying yellow, blue and black colours.

Example 2

A composition comprising a keto acid compound of formula (V) (an additional component) was formulated according to Table 6. All amounts are provided in weight percentage (wt%).

Table 6

A composition comprising an oxyanion of a multivalent metal (an additional component) was formulated according to Table 1 above. A composition comprising a diacetylene compound (an activatable component) was formulated according to Table 4 above, using the millbase formulations or Tables 2 and 3 the diacetylene compound being replaced by N1 ,N22- didecyldocosa-10, 12-diynediamide.

A layer of the composition comprising an oxyanion of a multivalent metal was applied to a paper substrate using a K2 K-bar applicator. A layer of the composition comprising a keto acid compound of formula (V) was then applied using a k2 k-bar applicator over the layer of the composition comprising an oxyanion of a multivalent metal. A layer of the composition comprising a diacetylene compound was then using a k2 k-bar applicator over the layer of the composition comprising a keto acid compound of formula (V).

The oxyanion of a multivalent metal, keto acid compound of formula (V) and diacetylene compound are in their non-coloured states.

Following application of the layers to the substrate, an additional temperature is applied to localised positions by IR radiation using a 10.6 pm C0 2 laser (20% power). The keto acid compound of formula (V) transitions from the non- coloured state to a yellow coloured state at the localised positions. The intensity of the yellow colour can be varied by alteration of the fluence provided by the C0 2 laser. It is noted that the additional temperature required to facilitate a transition of the keto acid compound of formula (V) from the non-coloured state to a coloured state is slightly lower than the additional temperature required to facilitate a transition of the oxyanion of a multivalent metal from a non-coloured to a coloured state. To provide such an additional temperature to facilitate the transition of the oxyanion of a multivalent metal from a non-coloured to a coloured state, the power of the C0 2 laser is increased to 38%. This facilitates the formation of the black coloured state of the oxyanion of a multivalent metal. The intensity of the black colour formed can be made to vary by variation of the fluence provided by the C0 2 laser. If the 38% power is utilised, as the coloured state of the oxyanion of a multivalent metal is formed at the same localised position at which the coloured state of the keto acid compound of formula (V) has been formed, the final colour displayed at these localised positions is dependent upon the black colour of the coloured state of the oxyanion of a multivalent metal, and the yellow colour of the coloured state of the keto acid compound of formula (V), i.e. the final colour at these localised positions results from the combination of colours of the coloured states of the two components. Accordingly, different yellow and black coloured states can be formed. It is noted that the activation temperature of the diacetylene compound is lower than both the additional temperatures. Accordingly, upon application of the IR radiation at the localised positions of the substrate, the non-coloured state of the diacetylene compound is activated at these localised positions.

Upon application of UV radiation to the substrate by flood illumination using a germicidal lamp (applied transition stimulus), the diacetylene compound transitions from the non-coloured state to a first blue coloured state at the localised positions at which the non-coloured state has been‘activated’. If the UV radiation has been applied following only the application of IR radiation using the C0 2 laser at 20% power, the colour displayed at the localised positions will be a combination of the blue of the first coloured state of the diacetylene compound and the yellow coloured state of the keto acid compound of formula (V). Accordingly, different blue and green colours can be formed. If further IR radiation (applied temperature) is applied using the C0 2 laser at 20% power at the localised positions at which the first coloured state of the diacetylene compound have been formed, the diacetylene compound transitions from the blue first coloured state to a red second coloured state. The intensity of the colour can be varied by variation of the fluence applied by the C0 2 laser. The colour displayed at the localised positions will be a combination of the red of the second coloured state of the diacetylene compound and the yellow coloured state of the keto acid compound of formula (V). Accordingly, different orange and red colours can be formed. It is noted that the applied temperature is lower than the additional temperature required to facilitate a transition of the oxyanion of a multivalent metal from the non-coloured to the coloured state. Accordingly, if instead the further IR radiation is applied using the C0 2 laser at 38% power, the additional temperature is reached and the oxyanion of a multivalent metal transitions from the non-coloured to a black coloured state. The intensity of the colour can be varied by variation of the fluence applied by the C0 2 laser. The colour displayed at the localised positions will be a combination of the red of the second coloured state of the diacetylene compound, the yellow coloured state of the keto acid compound of formula (V), and the black coloured state of the oxyanion of a multivalent metal. Accordingly, different red, brown and black colours can be formed. Alternatively, if the UV radiation (applied transition stimulus) has been applied following the application of IR radiation using a C0 2 laser at 38% power, the colour displayed at the localised positions will be a combination of the blue of the first coloured state of the diacetylene compound, the yellow coloured state of the keto acid compound of formula (V), and the black coloured state of the oxyanion of a multivalent metal. Accordingly, different green and black colours can be formed.

A multi-coloured image displaying yellow, black, green, blue, red, orange and brown colours can therefore be formed. Example 3

A composition comprising a leuco dye (an additional component) was formulated according to Table 7. All amounts are provided in weight percentage (wt%). Table 7

Table 8

A composition comprising a pyrazole (thio)semicarbazone compound of formula (III) was formulated according to Table 5, the pyrazole (thio)semicarbazone compound of formula (III) being replaced by (E)-2-((5-hydroxy-1 ,3-diphenyl-1 H- pyrazol-4-yl)(phenyl)methylene)-N-phenylhydrazine-1 -carboxamide.

A composition comprising a diacetylene compound (an activatable component) was formulated according to Table 4, using the millbase formulations of Tables 2 and 3 the diacetylene compound being replaced by N1 ,N22-didecyldocosa-10,12- diynediamide.

A layer of the composition comprising a leuco dye was applied to a paper substrate using a k2 k-bar applicator. A layer of the composition comprising a pyrazole (thio)semicarbazone compound of formula (III) was applied using a k2 k-bar applicator over the layer of the composition comprising the leuco dye. A layer of the composition comprising a diacetylene compound was then applied over the layer of the layer of the composition comprising a pyrazole (thio)semicarbazone compound of formula (III).

The leuco dye, pyrazole (thio)semicarbazone compound of formula (III) and diacetylene compound are in their non-coloured states. Following application of the layers to the substrate, IR radiation is applied to localised positions of the substrate using a 10.6 pm C0 2 laser (20% or 38% power) (additional temperature). The leuco dye transitions from the non- coloured to a pale blue coloured state. The intensity of the blue colour of the coloured state can be varied by alteration of the fluence applied by the C0 2 laser, e.g. by altering the power of the laser. It is noted that the activation temperature for the diacetylene compound is lower than the additional temperature required to facilitate a transition of the leuco dye from the non- coloured to a coloured state. Accordingly, at the localised positions to which the IR radiation is applied, the non-coloured state of the diacetylene compound is ‘activated’.

Upon further application of UV radiation by flood illumination using a germicidal lamp (applied transition stimulus), the ‘activated’ non-coloured state of the diacetylene compound transitions to a blue first coloured state at the localised positions. Upon application of the UV radiation by flood illumination, the pyrazole (thio)semicarbazone of formula (III) also transitions from the non- coloured to a yellow coloured state across the substrate, the UV radiation acting as the additional applied stimulus. A yellow colour is therefore formed across the substrate apart form at the localised positions at which the first coloured state of the diacetylene compound and the coloured state of the leuco dye have also been formed. At these localised positions, the colour displayed is a combination of the colour of blue first coloured state of the diacetylene compound, the pale blue coloured state of the leuco dye and the yellow coloured state of the pyrzole (thio)semicarbazone compound of formula (III). Accordingly, a very intense blue colour may be formed.

Upon further application of IR radiation using a 10.6 pm C0 2 laser (20% power), to some of the localised positions at which the blue first coloured state of the diacetylene compound has been formed, the blue first coloured state transitions to a red second coloured state. At these localised positions, the colour displayed is a combination of the colour of red second coloured state of the diacetylene compound, the pale blue coloured state of the leuco dye and the yellow coloured state of the pyrzole (thio)semicarbazone compound of formula (III). Accordingly, different red and orange colours may be formed.

A multi-coloured image displaying blue, red and yellow colours can therefore be formed.