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Title:
MODIFIED DIENE ELASTOMERS
Document Type and Number:
WIPO Patent Application WO/2011/083050
Kind Code:
A2
Abstract:
The invention is related to a process for grafting silane or silicone functionality onto a diene elastomer, comprising reacting the diene elastomer with an unsaturated monomer (A) containing an olefinic–C=C-bond or acetylenic -C≡C- bond and a reactive functional group X with an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A). According to the invention, the unsaturated monomer (A) has the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety containing the reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH-or -C≡C- bond. According to a second aspect of the invention, the unsaturated monomer (A') contains at least two groups of the formula R"- CH=CH-Z'-(III) or R"-C≡C-Z'-(IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH-or -C≡C-bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH-or -C≡C-bond, and the functional group Y of the organosilicon compound (B) is capable of reacting with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV). Such elastomer composition can be used to produce tires with good rolling resistance.

Inventors:
BACKER MICHAEL (BE)
CHAUSSEE THOMAS (FR)
DE BUYL FRANCOIS (BE)
DEHEUNYNCK DAMIEN (BE)
HABIMANA JEAN DE LA CROIX (BE)
SMITS VALERIE (BE)
Application Number:
EP2010/070489
Publication Date:
July 14, 2011
Filing Date:
December 22, 2010
Export Citation:
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Assignee:
DOW CORNING (US)
BACKER MICHAEL (BE)
CHAUSSEE THOMAS (FR)
DE BUYL FRANCOIS (BE)
DEHEUNYNCK DAMIEN (BE)
HABIMANA JEAN DE LA CROIX (BE)
SMITS VALERIE (BE)
International Classes:
C08F253/00
Domestic Patent References:
WO2010125123A12010-11-04
WO2010125124A12010-11-04
Foreign References:
US6828411B22004-12-07
EP0735088A11996-10-02
Other References:
MICHAEL B. SMITH; JERRY MARCH: "March's Advanced Organic Chemistry", 2001, JOHN WILEY & SONS, pages: 1062
B.C. RANU; S. BANERJEE, TETRAHEDRON LETTERS, vol. 48, no. 1, 2007, pages 141 - 143
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 60, 1930, pages 304
THE VANDERBILT RUBBER HANDBOOK, 1978, pages 344 - 346
Attorney, Agent or Firm:
DONLAN, Andrew et al. (Barry South Glamorgan CF63 2YL, GB)
Download PDF:
Claims:
CLAIMS

A process for grafting silane or silicone functionality onto a diene elastomer, comprising reacting the diene elastomer with an unsaturated monomer (A) containing an olefinic -C=C- bond or acetylenic -C≡C- bond and a reactive functional group X with an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A), characterized in that the unsaturated monomer (A) has the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety containing the reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the

-CH=CH- or -C≡C- bond.

A process for grafting silane or silicone functionality onto a diene elastomer, comprising reacting the diene elastomer with an unsaturated monomer (Α') containing an olefinic -C=C- bond or acetylenic -C≡C- bond in the presence of an organosilicon compound (B) having a functional group Y which is reactive with the unsaturated monomer (Α'), characterized in that the unsaturated monomer (Α') contains at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the functional group Y of the organosilicon compound (B) is capable of reacting with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV).

A process according to Claim 1 or Claim 2 characterised in that the diene elastomer is reacted simultaneously with the unsaturated monomer (A) or (Α') and the organosilicon compound (B).

A process composition according to any preceding claim characterised in that the diene elastomer is natural rubber.

A process according to claim 4 characterised in that the diene elastomer is a homopolymer or copolymer of a diene monomer.

6. A process according to any preceding claim characterised in that the unsaturated monomer (A) or (Α') and the silicon compound (B) and the diene elastomer are reacted together at a temperature in the range of 90°C to 200°C, preferably 120°C to 180°C.

7. A process according to any preceding claim characterised in that a filler is

introduced into the diene elastomer during and/or subsequent to grafting.

8. A process according to any preceding claim characterised in that the filler is silica.

9. A composition comprising a diene elastomer and an unsaturated monomer (A) containing an olefinic -C=C- bond or acetylenic -C≡C- bond and a reactive functional group X, characterized in that the unsaturated monomer (A) has the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron- withdrawing moiety containing the reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the composition contains an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A).

10. A composition according to Claim 9 characterised in that the unsaturated monomer (A) is glycidyl acrylate and the organosilicon compound (B) contains an aminoalkyl group preferably N-aminopropyltriethoxysilane, methylaminopropyltriethoxysilane or phenylaminopropyltriethoxysilane.

1 1 . A composition comprising a diene elastomer and an unsaturated monomer (Α') containing an olefinic -C=C- bond or acetylenic -C≡C- bond, characterized in that the unsaturated monomer (Α') contains at least two groups of the formula

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the composition contains an organosilicon compound (B) having a functional group Y which is reactive with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV).

12. A composition according to Claim 1 1 characterised in that the unsaturated

monomer (A) is an acrylate ester of a polyhydric alcohol and the organosilicon compound (B) contains a primary or secondary aminoalkyi group or a mercaptoalkyi group.

13. A composition according to Claim 1 1 characterised in that the unsaturated

monomer (A) is pentaerythritol triacrylate, pentaerythritol tetraacrylate,

trimethylolpropane triacrylate, propane-1 ,2-diol diacrylate or propane-1 ,3-diol diacrylate .

14. A composition according to any of Claims 9 to 13 characterised in that the

unsaturated monomer (A) or (Α') is present at 0.5 to 20.0% by weight based on the diene elastomer.

15. A composition according to any of claims 9 to 14 characterised in that the

organosilicon compound (B) is a silane containing the functional group Y and a hydrolysable group.

16. A composition according to Claim 15 characterised in that the hydrolysable group is of the formula -SiRaR'(3-a) wherein each R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive.

17. A composition according to Claim 15 or Claim 16 characterised in that the

unsaturated silane is partially hydrolyzed and condensed into oligomers.

18. A composition according to any of claims 9 to 14 characterised in that the

organosilicon compound (B) is a branched silicone resin containing T units of the formula Y-Q-Si03/2 wherein Q is a divalent organic linkage bonded to the branched silicone resin through a C-Si bond.

19. A composition according to Claim 18, characterized in that the branched silicone resin contains hydrolysable Si-OR' groups, in which R' represents an alkyl group having 1 to 4 carbon atoms.

20. A composition according to any of claims 9 to 14 characterised in that the

organosilicon compound (B) is a mainly linear organopolysiloxane fluid containing at least one group of the formula Y-Q'- wherein Q' is a divalent organic linkage bonded to the organopolysiloxane fluid through a C-Si bond.

21 . A composition according to Claim 20 characterised in that the organopolysiloxane fluid is polydimethylsiloxane having at least one terminal group of the formula Y-Q'- wherein Q' is a divalent organic linkage bonded to the organopolysiloxane fluid.

22. A composition according to Claim 20 and 21 characterised in that the formula

Y-Q'- wherein Q' is a divalent organic linkage is bonded to the organopolysiloxane fluid through a C-Si bond

23. A process according to Claim 2, characterised in that the unsaturated monomer (Α') is reacted with the organosilicon compound (B) in such proportions that the reaction product contains on average at least one unsaturated moiety of the formula

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) per molecule and at least one organosilicon moiety per molecule, and the said reaction product is reacted with the diene elastomer.

24. A process for grafting silane or silicone functionality onto a diene elastomer,

characterized in that an unsaturated monomer (A), containing at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, is reacted with an organosilicon compound (B) having a functional group Y which is reactive with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV), in such proportions that the reaction product contains on average at least one unsaturated moiety of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) per molecule and at least one organosilicon moiety per molecule, and the said reaction product is reacted with the diene elastomer.

25. An ester of a polyhydric alcohol, characterized in that the ester contains at least one carboxylic ester group of the formula -0-C(0)-CH=CH-R", and at least one carboxylic ester group of the formula -0-C(0)-CH2-CHR"-X'-A'-SiRaR'(3-a) Or -0-C(0)-CH(CH2R")-X'-A'-SiRaR'(3-a) where R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, X' represents a -S- or -NR*- linkage, R* being H or an alkyl group having 1 to 4 carbon atoms, A represents a divalent organic group, R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive.

26. An ester according to Claim 25 characterised in that the ester contains at least one acrylate ester moiety and at least one 3-(trialkoxysilylalkylamino)propionate ester moiety.

27. A process for the preparation of an ester according to Claim 25 or Claim 26,

characterised in that an ester of a polyhydric alcohol containing at least two carboxylic ester groups of the formula -0-C(0)-CH=CH-R" is reacted with an aminoalkylsilane of the formula R*NH-A'- SiRaR'(3-a) or a mercaptoalkylsilane of the formula HS-A'- SiRaR'(3-a) in such proportions that the carboxylic ester groups of the formula -0-C(0)-CH=CH-R" are present in molar excess with respect to the amino groups of the aminoalkylsilane or the mercapto groups of the mercaptoalkylsilane.

28. A composition comprising a diene elastomer and an ester according to Claim 25 or 26.

29. Use of an unsaturated monomer (A) or (Α') having the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety substituted by a reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, in conjunction with a silicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A), in grafting silane or silicone functionality onto a diene elastomer, to give enhanced grafting compared to an olefinically unsaturated silane not containing a -CH=CH-Z- or -C≡C-Z- moiety.

30. A process for the production of a rubber article from a composition in accordance with any one of claims 9 to 21 characterised in that the filled elastomer composition is shaped and cured.

31 . A process according to claim 30 in that the composition contains a suitable curing system selected from sulphur, peroxide or a sulphur compound.

32. A process according to claim 30 in that the composition is cured by moisture.

33. A process according to claim 32 in that the moisture cure is accelerated by a

hydrolysis/condensation catalyst.

34. Use of an ester of a polyhydric alcohol, containing at least one carboxylic ester group of the formula -0-C(0)-CH=CH-R", and at least one carboxylic ester group of the formula -0-C(0)-CH2-CHR"-X,-A"-SiRaR, (3-a) Or -0-C(0)-CH(CH2R")-X'-A'- SiRaR'(3-a) where R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, X' represents a -S- or -NR*- linkage, R* being H or an alkyl group having 1 to 4 carbon atoms or a group of the formula -A"-SiRaR'(3-a), A' represents a divalent organic group, R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive, in grafting silane or silicone functionality onto a diene elastomer, to give enhanced grafting compared to an olefinically unsaturated silane not containing a group of the formula -0-C(0)-CH=CH-R".

35. Use of the curable rubber composition produced by the process of any of Claims 1 to 22 in the production of tires or any parts thereof or engineered rubber goods, belts, or hoses.

Description:
MODIFIED DIENE ELASTOMERS

[0001] This invention relates to a process for modifying a diene elastomer by grafting a silane or silicone thereto. This invention also relates to the graft polymers produced.

[0002] By a diene elastomer we mean a polymer having elastic properties at room temperature, mixing temperature or at the usage temperature, which can be polymerized from a diene monomer. Typically, a diene elastomer is a polymer containing at least one ene (carbon-carbon double bond, C=C) having a hydrogen atom on the alpha carbon next to the C=C bond. The diene elastomer can be a natural polymer such as natural rubber or can be a synthetic polymer derived at least in part from a diene.

[0003] A process according to the present invention for grafting silane or silicone functionality onto a diene elastomer comprises reacting the diene elastomer with an unsaturated monomer (A) containing an olefinic -C=C- bond or acetylenic -C≡C- bond and a reactive functional group X in the presence of means capable of generating free radical sites in the diene elastomer and with a silicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A), characterized in that the unsaturated monomer (A) has the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety containing the reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond.

[0004] A process according to another aspect of the invention for grafting silane or silicone functionality onto a diene elastomer comprises reacting the diene elastomer with an unsaturated monomer (Α') containing an olefinic -C=C- bond or acetylenic -C≡C- bond in the presence of means capable of generating free radical sites in the diene elastomer and with an organosilicon compound (B) having a functional group Y which is reactive with the unsaturated monomer (Α'), characterized in that the unsaturated monomer (Α') contains at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the functional group Y of the organosilicon compound (B) is capable of reacting with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV). [0005] A composition according to one aspect of the invention comprises a diene elastomer and an unsaturated monomer (A) containing an olefinic -C=C- bond or acetylenic -C≡C- bond and a reactive functional group X, characterized in that the unsaturated monomer (A) has the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety containing the reactive functional group X and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the composition contains an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A).

[0006] A composition according to another aspect of the invention comprises a diene elastomer and an unsaturated monomer (Α') containing an olefinic -C=C- bond or acetylenic -C≡C- bond, characterized in that the unsaturated monomer (Α') contains at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, and the composition contains an organosilicon compound (B) having a functional group Y which is reactive with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV).

[0007] The invention includes an ester of a polyhydric alcohol, characterized in that the ester contains at least one carboxylic ester group of the formula -0-C(0)-CH=CH-R" and at least one carboxylic ester group of the formula -0-C(0)-CH 2 -CHR"-X'-A"-SiR a R'<3-a) Or

-0-C(0)-CH(CH 2 R")-X'-A"-SiR a R'(3-a) where R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, X' represents a -S- or -NR * - linkage, R * being H or an alkyl group having 1 to 4 carbon atoms, A" represents a divalent organic group, R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive. The invention also includes the use of such an ester in grafting silane or silicone functionality onto a polyolefin, to give enhanced grafting compared to an olefinically unsaturated silane not containing a group of the formula

-0-C(0)-CH=CH-R". [0008] It will be appreciated that the high shear rate generated by a melt extrusion process can generate free radical sites in the diene elastomer. However, it has been identified that whilst it is possible to use an "external" means capable of generating free radicals when grafting the silicone onto a diene elastomer none are required. By "external means for generating free radical sites in the diene elastomer", we mean additional to normal processing steps such as shear rate due to mixing). Hence, the introduction of a compound capable of generating free radicals, and thus capable of generating free radical sites in the diene elastomer e.g. organic peroxides or azo compounds may be used but is not necessary for the invention to function. Preferably, if present, the radical formed by the decomposition of the free-radical initiator is an oxygen-based free radical. Other possible means include applying heat from an external heat source or irradiation such as electron beam radiation. Preferably the process as described herein is undertaken in the absence of an "external" means for generating free radical sites in the diene elastomer. [0009] A process according to the invention for the preparation of such an ester is characterised in that an ester of a polyhydric alcohol containing at least two carboxylic ester groups of the formula -0-C(0)-CH=CH-R" is reacted with an aminoalkylsilane of the formula R*NH-A"- SiR a R'(3-a) or a mercaptoalkylsilane of the formula HS-A"- SiR a R'(3-a) in such proportions that the carboxylic ester groups of the formula -0-C(0)-CH=CH-R" are present in molar excess with respect to the amino groups of the aminoalkylsilane or the mercapto groups of the mercaptoalkylsilane.

[0010] The invention also includes the use of an unsaturated monomer (A) having the formula R"-CH=CH-Z (I) or R"-C≡C-Z (II) in which Z represents an electron-withdrawing moiety substituted by a reactive functional group X, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, in conjunction with an organosilicon compound (B) having a functional group Y which is reactive with the functional group X of the unsaturated monomer (A), in grafting silane or silicone functionality onto a diene elastomer, to give enhanced grafting compared to an olefinically unsaturated silane not containing a -CH=CH-Z- or -C≡C-Z- moiety.

[0011] The invention further includes the use of an unsaturated monomer (Α') containing at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, in conjunction with a silicon compound (B) having a functional group Y capable of reacting with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV), in grafting silane or silicone functionality onto a diene elastomer, to give enhanced grafting compared to an olefinically unsaturated silane not containing a R"-CH=CH-Z'- or R"-C≡C-Z'- moiety.

[0012] We have found according to the invention that the use of an unsaturated monomer (A) or (Α') containing an electron withdrawing moiety Z or Z' in carrying out the grafting reaction on the diene elastomer gives an enhanced grafting yield compared to grafting with an olefinically unsaturated silane such as vinyltrimethoxysilane not containing an electron withdrawing moiety such as Z or Z' or compared to grafting with any other unsaturated monomer not containing an electron withdrawing moiety such as Z or Z'. The enhanced grafting efficiency can lead to a silane grafted polymer with enhanced physical properties resulting in enhanced filler dispersion which impacts the physical properties of the cured composition.

[0013] An electron-withdrawing moiety is a chemical group which draws electrons away from a reaction center. The electron-withdrawing moiety Z or the electron-withdrawing linkage Z' can in general comprise any of the divalent linkages listed as dienophiles in

Michael B. Smith and Jerry March; March's Advanced Organic Chemistry, 5 th edition, John Wiley & Sons, New York 2001 , at Chapter 15-58 (page 1062). The electron-withdrawing linkage in Z or Z' can be especially a C(=0)R * , C(=0)OR * , OC(=0)R * , C(=0)Ar linkage in which Ar represents arylene and R * represents a divalent hydrocarbon moiety. Z or Z' can alternatively contain a C(=0)-NH-R * linkage. In the electron-withdrawing moiety Z, the electron withdrawing carboxyl, carbonyl, or amide linkage represented by C(=0)R * , C(=0)OR * , OC(=0)R * , C(=0)Ar or C(=0)-NH-R * can be bonded to the reactive functional group X through a divalent organic spacer linkage comprising at least one carbon atom separating the C(=0)R * , C(=0)OR * , OC(=0)R*, C(=0)Ar or C(=0)-NH-R * linkage from the reactive functional group X. Z or Z' cannot be an electron-donating group, for example alcohol group, amino group, or terminal alkyl group such as methyl which furthermore produces steric hindrance to the -CH=CH- or -C≡C- bond. [0014] In a preferred embodiment, the composition contains not only (A) or (Α') monomer together with compound (B) but also an olefinically unsaturated silane having at least one hydrolysable group bonded to silicon, characterized in that the silane has the formula: · R"-CH=CH-C(0)A-B-SiR a R'(3-a) (I) or

R"-C≡C-C(0)A-B-SiR a R'(3-a) (II) in which R represents a hydrolysable group; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; a has a value in the range 1 to 3 inclusive; B represents a divalent organic spacer linkage comprising at least one carbon atom separating the linkage -C(0)X- from the Si atom, and R" represents hydrogen or a group having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond; A is selected from S and O. Such olefinically unsaturated silane is described in WO2010/125123 and WO2010/125124. [0015] The diene elastomer can be natural rubber. We have found that the unsaturated compound (A) or (Α') of the invention graft readily to natural rubber.

[0016] The diene elastomer can alternatively be a synthetic polymer which is a

homopolymer or copolymer of a diene monomer (a monomer bearing two double carbon- carbon bonds, whether conjugated or not). Preferably the elastomer is an "essentially unsaturated" diene elastomer, that is a diene elastomer resulting at least in part from conjugated diene monomers, having a content of members or units of diene origin

(conjugated dienes) which is greater than 15 mol %. More preferably it is a "highly unsaturated" diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50 mol%. Diene elastomers such as butyl rubbers, copolymers of dienes and elastomers of alpha-olefins of the ethylene-propylene diene monomer (EPDM) type, which may be described as "essentially saturated" diene elastomers having a low (less than 15 mol%) content of units of diene origin, can alternatively be used but are less preferred.

[0017] The diene elastomer can for example be:

(a) any homopolymer obtained by polymerization of a conjugated diene monomer having 4 to 12 carbon atoms; (b) any copolymer obtained by copolymerization of one or more dienes conjugated together or with one or more vinyl aromatic compounds having 8 to 20 carbon atoms;

(c) a ternary copolymer obtained by copolymerization of ethylene, of an [alpha]-olefin having 3 to 6 carbon atoms with a non-conjugated diene monomer having 6 to 12 carbon atoms, such as, for example, the elastomers obtained from ethylene, from propylene with a non-conjugated diene monomer of the aforementioned type, such as in particular 1 ,4-hexadiene, ethylidene norbornene or dicyclopentadiene;

(d) a copolymer of isobutene and isoprene (butyl rubber), and also the halogenated, in particular chlorinated or brominated, versions of this type of copolymer.

[0018] Suitable conjugated dienes are, in particular, 1 ,3-butadiene, 2-methyl-1 ,3-butadiene, alkyl)-1 ,3-butadienes such as, for instance, 2,3-dimethyl-1 ,3-butadiene, 2,3- diethyl-1 ,3-butadiene, 2-methyl-3-ethyl-1 ,3-butadiene, 2-methyl-3-isopropyl-1 ,3-butadiene, an aryl-1 ,3-butadiene, 1 ,3-pentadiene and 2,4-hexadiene. Suitable vinyl-aromatic

compounds are, for example, styrene, ortho-, meta- and para-methylstyrene, the commercial mixture "vinyltoluene", para-tert.-butylstyrene, methoxystyrenes, chlorostyrenes,

vinylmesitylene, divinylbenzene and vinylnaphthalene. [0019] The copolymers may contain between 99% and 20% by weight of diene units and between 1 % and 80% by weight of vinyl aromatic units. The elastomers may have any microstructure, which is a function of the polymerization conditions used, in particular of the presence or absence of a modifying and/or randomizing agent and the quantities of modifying and/or randomizing agent used. The elastomers may for example be block, statistical, sequential or microsequential elastomers, and may be. prepared in dispersion or in solution ' ; they may be coupled and/or starred or alternatively furtctionalized with a coupling and/or starring or functionalizing agent. Examples of preferred block copolymers are styrene-butadiene-styrene (SBS) block copolymers and styrene-ethylene/butadiene-styrene (SEBS) block copolymers.

The elastomer can be epoxidised rubber, for example Epoxidised Natural Rubber (ENR). Epoxidised rubber is obtained by modifying rubber, for example natural rubber, in which some insaturation are replaced by epoxy groups through a chemical modification. Useful epoxidized rubber will have an extent of epoxidation of about 5 to about 95 mole %, preferably from about 15 to about 80 mole %, and more preferably from about 20 to about 50 mole %, where the extent of epoxidation is defined as the mole percentage of olefinically unsaturated sites originally present in the rubber that have been converted to oxirane, hydroxyl, or ester groups. Epoxidation reactions can be effected by reacting an unsaturated rubber with an epoxidizing agent. Useful epoxidizing agents include peracids such as m-chloroperbenzoic acid and peracetic acid. Other examples include carboxylic acids, such as acetic and formic acid, or carboxylic anhydrides such as acetic anhydride, together with hydrogen peroxide. A catalyst, such as sulfuric acid, p-tolulene sulfonic acid, or a cationic exchange resin such as sulfonated polystyrene may optionally be employed.

Epoxidation is preferably conducted at a temperature from about 0° to about 150° C. and preferably from about 25° to about 80° C. The time required to effect the epoxidation reaction is typically from about 0.25 to about 10 hours, and preferably from about 0.5 to about 3 hours.

The epoxidation reaction is preferably conducted in a solvent that is capable of substantially dissolving the rubber both in its original condition and after epoxidation. Suitable solvents include aromatic solvents such as benzene, tolulene, xylene, and chlorobenzene, as well as cycloaliphatic solvents such as cyclohexane, cycloheptane, and mixtures thereof.

After epoxidation, the epoxidized rubber is preferably removed or isolated from the acidic environment, which may include the epoxidizing agents as well as the acidic catalyst. This isolation can be accomplished via filtration, or by adding a dilute aqueous base to neutralize the acid and then subsequently coagulate the polymer. The polymer can be coagulated by using an alcohol such as methanol, ethanol, or propanol. An antioxidant is typically added after the isolation procedure, and the final product may be dried using techniques such as vacuum distillation. Alternatively, other known methods for removing polymers from hydrocarbon solvents and the like may be employed including steam stripping and drum drying.

Other diene elastomer can also be used in epoxydised form such as, but not limited to, those rubbers that derive from the polymerization of conjugated dienes alone or in combination with vinyl aromatic monomers. [0020] Preferred are polybutadienes, and in particular those having a content of 1 ,2-u nits between 4% and 80%, or those having a content of cis-1 ,4 of more than 80%, polyisoprenes, butadiene-styrene copolymers, and in particular those having a styrene content of between 5% and 50% by weight and, more particularly, between 20% and 40%, a content of 1 ,2- bonds of the butadiene fraction of between 4% and 65%, and a content of trans-1 ,4 bonds of

between 20% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90% by weight. In the case of butadiene-styrene- isoprene copolymers, those which are suitable are in particular those having a styrene content of between 5% and 50% by weight and, more particularly, between 10% and 40%, an isoprene content of between 15% and 60% by weight, and more particularly between 20% and 50%, a butadiene content of between 5% and 50% by weight, and more particularly between 20% and 40%, a content of 1 ,2-units of the butadiene fraction of between 4% and 85%, a content of trans-1 ,4 units of the butadiene fraction of between 6% and 80%, a content of 1 ,2- plus 3,4-units of the isoprene fraction of between 5% and 70%, and a content of trans-1 ,4 units of the isoprene fraction of between 10% and 50%.

[0021] The elastomer can be an alkoxysilane-terminated diene polymer or a copolymer of the diene and an alkoxy-containing molecule prepared via a tin coupled solution

polymerization.

[0022] Examples of reactive groups X in the unsaturated monomer (A) are amino groups, which can be reacted with epoxide groups or isocyanate groups as reactive groups Y;

hydroxyl groups, which can be reacted with isocyanate groups; epoxide groups, which can be reacted with amino groups or hydroxyl groups; aldehyde groups, which can be reacted with amino groups and isocyanate groups which can be reacted with amino groups or hydroxyl groups.

[0023] An unsaturated monomer (A) may have an electron-withdrawing linkage such as C(=0)R*, C(=0)OR * , OC(=0)R * , C(=0)Ar or C(=0)-NH-R * bonded to the reactive functional group X through a divalent organic spacer linkage such as an alkylene linkage having for example 1 to 6 carbon atoms. The unsaturated monomer (A) can for example be glycidyl acrylate

having an electron-withdrawing moiety (Z) comprising a C(=0)OCH 2 linkage and an epoxide functional group X or can be a hydroxyalkyl acrylate ester such as 2-h yd roxy ethyl acrylate. We have found that use of an acrylate ester such as glycidyl acrylate grafts to diene elastomers more readily than glycidyl methacrylate. The unsaturated monomer (A) can alternatively be pentaerythritol triacrylate, vinyl acrylate. Preferably, the unsaturated monomer (A) is glycidyl acrylate and the organosilicon compound (B) contains an aminoalkyi group.

[0024] An unsaturated monomer (Α') has at least two groups of the formula

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' comprises an electron-withdrawing divalent linkage such as C(=0)R*, C(=0)OR * , OC(=0)R * , C(=0)Ar or C(=0)-NH-R*. The groups of the formula R"-CH=CH-Z'- (III) or R"-CsC-Z'- (IV) are bonded to a core moiety of the unsaturated monomer (Α') either directly or through a divalent organic spacer linkage such as an alkylene linkage having for example 1 to 6 carbon atoms. The unsaturated monomer (Α') can for example be an acrylate ester of a polyhydric alcohol, for example a polyhydric alcohol having 2 to 6 -OH groups. The olefinic CH 2 =CH bond of the acrylate is bonded through a C(=0)0 linkage acting as Z'. Examples of suitable acrylate esters of polyhydric alcohols include pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, propane-1 ,2-diol diacrylate and propane-1 ,3-diol diacrylate.

[0025] The organosilicon compound (B) for use with an unsaturated monomer (A) has a functional group Y which is chosen to be reactive with the functional group X of the unsaturated monomer (A). The functional group Y can for example be an amino group to react with an aldehyde, epoxide or isocyanate group X from the unsaturated monomer (A), an epoxide group to react with an amino group X from the unsaturated monomer (A), or an isocyanate group to react with an amine or hydroxyl group X from the unsaturated monomer (A). The functional group Y is generally present in Y as a substituted alkyl group, for example an aminoalkyi group, such as:

-(CH 2 ) 3 NH 2 ,

-(CH 2 ) 4 NH 2 ,

-(CH 2 ) 3 NH(CH 2 ) 2 NH 2 ,

-CH 2 CH(CH 3 )CH 2 NH(CH 2 ) 2 NH 2 ,

-(CH 2 ) 3 NHCH 2 CH 2 NH(CH 2 ) 2 NH 2 ,

-CH 2 CH(CH 3 )CH 2 NH(CH 2 ) 3 NH 2 ,

-(CH 2 ) 3 NH(CH 2 ) 4 NH 2 and

-(CH 2 ) 3 0(CH 2 ) 2 NH 2i an epoxyalkyl group such as 3-glycidoxypropyl or an isocyanatoalkyl group such as 3- isocyanatopropyl or mercaptoalkyl such as 3-mercaptopropyl. [0026] The organosilicon compound (B) for use with an unsaturated monomer (Α') has a functional group Y which is reactive with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV). The functional group Y can for example be reactive with the olefinic or acetylenic bond via Michael addition. Examples of functional groups Y which are reactive with an olefinic or acetylenic bond via Michael addition include primary and secondary amine groups and mercapto groups.

[0027] Examples of suitable organosilicon compounds (B) for use with an unsaturated monomer (Α') thus include compounds having an aminoalkyl group, for example a group of the formula R*NH-A"- where R * is H or an alkyl group having 1 to 4 carbon atoms or a group of the formula -A"-SiR a R'(3 -a ), and A" is a divalent organic group, or a mercaptoalkyl group, such as 3-mercaptopropyl, bonded to a silicon atom.

[0028] The Michael addition reaction of amino groups or mercapto groups to an activated olefinic or acetylenic bond such as that present in the group R"-CH=CH-Z'- (III) or

R"-C≡C-Z'- (IV), for example an acrylate ester group, proceeds readily at ambient temperature. It can be catalysed by strong acid or base or by Lewis acids but also proceeds readily without a catalyst, as described by B.C. Ranu and S. Banerjee, Tetrahedron Letters, vol.48, lss.1 , pp.141-143 (2007). · Preferably, the usaturated monomer (Α') is an acrylate ester of a polyhydric alcohol and the organosilicon compound (B) contains a primary or secondary aminoalkyl group or a mercaptoalkyl group.

[0029] Alternatively the component (Α') can react via diels alder reaction with conjugated diene compound such as sorbyloxysilane, cyclopentadiene silane as described in US 6,828,41 1 (B2).

[0030] For many uses the silicon compound (B) is preferably a silane containing the functional group Y and containing at least one hydrolysable group. Such hydrolysable silanes, when reacted onto a diene elastomer grafted with the unsaturated monomer (A), can crosslink the diene elastomer, for example by exposure of the reaction product to moisture and a silanol condensation catalyst. The hydrolysable group of the silane preferably has the formula - SiR a R'<3-a) wherein R represents a hydrolysable group, especially an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive. Each

hydrolysable group R in the- SiR a R'<3-a) group is preferably an alkoxy group, although alternative hydrolysable groups such as acyloxy, for example acetoxy, ketoxime, for example methylethylketoxime, alkyllactato, for example ethyllactato, amido, aminoxy or alkenyloxy groups can be used provided that they do not react with the functional groups X of

unsaturated monomer (A). Alkoxy groups R generally each have a linear or branched alkyl chain of 1 to 6 carbon atoms and most preferably are methoxy or ethoxy groups. The value of a can for example be 3, for example the silane can be a trimethoxy silane, to give the maximum number of crosslinking sites. However each alkoxy group generates a volatile organic alcohol when it is hydrolysed, and it may be preferred that the value of a is 2 or even 1 to minimize the volatile organic material emitted during crosslinking. The group R' if present is preferably a methyl or ethyl group.

[0031] The silane used as silicon compound (B) can be partially hydrolysed and

condensed into oligomers containing siloxane linkages. Usually it is preferred that such oligomers still contain at least one hydrolysable group bonded to Si per unsaturated silane monomer unit, so that the graft polymer has sufficient reactivity towards itself and towards polar surfaces and materials. If the grafted polymer is to be crosslinked, it is usually preferred that hydrolysis of the silane before grafting should be minimized. [0032] Examples of preferred amino functional hydrolysable silanes include 3- aminopropyltriethoxysilane, aminopropyltrimethoxysilane and 2-methyl-3- aminopropyltrimethoxysilane, which can for example be reacted with diene elastomer grafted with epoxide groups derived from glycidyl acrylate. The amino functional hydrolysable silane can alternatively be a bis-silane in which the group R * is a group of the formula -A"-SiR a R'(3-a), for example The bis-silane of the formula

(CH 3 0)3Si-CH2-CH2-CH2- H-CH2-CH2-CH2-Si(OCH3)3. Examples of preferred isocyanate functional hydrolysable silanes include 3-isocyanatopropyltriethoxysilane and 3- isocyanatopropyltrimethoxysilane, which can for example be reacted with diene elastomer grafted with hydroxyl groups derived for example from 2-hydroxyethyl acrylate. [0033] The silicon compound (B) can alternatively be a polyorganosiloxane.

Polyorganosiloxanes, also known as silicones, generally comprise siloxane units selected from R3S1O1/2 (M units), R 2 SiC>2/2 (D units), RSi0 3 /2 (T units) and Si0 4 /2 (Q units), in which each R represents an organic group or hydrogen or a hydroxyl group.

[0034] The silicon compound (B) can for example be a branched silicone resin containing T and/or Q units, optionally in combination with M and/or D units. Branched silicone resins can for example be prepared by the hydrolysis and condensation of hydrolysable silanes such as alkoxysilanes. Trialkoxysilanes such as alkyltrialkoxysilanes generally lead to T units in the silicone resin and tetraalkoxysilanes generally lead to Q units. Branched silicone resins comprising T units containing a reactive group Y can be formed by hydrolysis and condensation of trialkoxysilanes containing aminoaikyi, epoxyalkyi or isocyanatoalkyi groups, for example the trialkoxysilanes described above. The branched silicone resin can for example comprise mainly or predominantly T units, in which case 0.1 to 100 mole % of the siloxane T units present may contain the reactive group Y. The branched silicone resin can alternatively be a MQ resin in which most of the siloxane units present in the branched silicone resin are selected from Q units and M units. Reactive groups Y can be introduced by reacting a trialkoxysilane containing aminoaikyi, epoxyalkyi or isocyanatoalkyi group with a monoalkoxysilane such as trimethylmethoxysilane and a tetraalkoxysilane such as tetraalkoxysilane, introducing some T units containing reactive groups Y into the MQ resin.

• Preferably, the organosilicon compound (B) is a branched silicone resin containing

T units of the formula Y-Q-S1O3/2 wherein Q is a divalent organic linkage bonded to the branched silicone resin through a C-Si bond.

More preferably, the branched silicone resin contains hydrolysable Si-OR' groups, in which R' represents an alkyl group having 1 to 4 carbon atoms.

Preferably the organosilicon compound (B) is a mainly linear organopolysiloxane fluid containing at least one group of the formula Y-Q'- wherein Q' is a divalent organic linkage bonded to the organopolysiloxane fluid through a C-Si bond.

More preferably, the organopolysiloxane fluid is polydimethylsiloxane having at least one terminal group of the formula Y-Q'- wherein Q' is a divalent organic linkage bonded to the organopolysiloxane fluid. More preferably the formula Y-Q'- wherein Q' is a divalent organic linkage is bonded to the organopolysiloxane fluid through a C-Si bond.

[0035] An alternative polyorganosiloxane suitable as silicon compound (B) is a

substantially linear organopolysiloxane in which at least 50 mole % of the siloxane units are D units, for example polydimethylsiloxane, comprising at least one group containing a reactive group Y. The linear organopolysiloxane can for example contain aminoalkyl, epoxyalkyl or isocyanatoalkyl groups either as terminal groups or as groups pendant to the polydiorganosiloxane chain. Reaction with the diene elastomer and the unsaturated compound (A) in the presence of means capable of generating free radical sites in the diene elastomer can form a diene elastomer polydiorganosiloxane blend stabilised by grafting of the polydiorganosiloxane to the diene elastomer through grafted units of unsaturated compound (A). [0036] The process of the invention can be carried out in different procedures. In one preferred procedure the diene elastomer is reacted simultaneously with the unsaturated monomer (A) or (Α') and the silicon compound (B). Preferably this is done in the presence of means capable of generating free radical sites in the polymer. Grafting of the unsaturated monomer (A) or (Α') takes place simultaneously with reaction of the reactive groups X of (A) with the reactive groups Y of silicon compound (B) or reaction of the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) of (Α') with the reactive groups Y of silicon compound (B). A grafted diene elastomer containing silane or silicone " moieties derived from the silicon compound (B) is produced. If the silicon compound (B) contains hydrolysable groups, the grafted polymer will contain hydrolysable groups. This process has the advantage of grafting the

unsaturated monomer (A) and the silicon compound (B) in a single step process.

[0037] Alternatively the process of the invention can be carried out by sequential steps. The diene elastomer can be reacted with the unsaturated monomer (A) or (Α') and then the reaction product is reacted with the silicon compound (B).

[0038] A filler can be present in any of the mixing stage. Preferably, a filler is introduced into the diene elastomer during and/or subsequent to grafting. Preferably, the filler is silica. The temperature at which the diene elastomer and the unsaturated monomer (A) are reacted is generally above 80°C, usually above 120°C. Preferably, the unsaturated monomer (A) or (Α') and the silicon compound (B) and the diene elastomer are reacted together at a temperature in the range of 90°C to 200°C, preferably 120°C to 180°C.

[0039] In an alternative procedure the unsaturated monomer (A) or (Α') can be reacted with the organosilicon compound (B) before being reacted with the diene elastomer. In one preferred process an unsaturated monomer (Α') can be reacted with the organosilicon compound (B) in such proportions that the reaction product contains on average at least one unsaturated moiety of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) per molecule and at least one organosilicon moiety per molecule, and the said reaction product can be reacted with the diene elastomer optionally in the presence of means capable of generating free radical sites in the diene elastomer. The proportions of unsaturated monomer (Α') and organosilicon compound (B) reacted are such that the unsaturated groups

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) of unsaturated monomer (Α') are present in molar excess with respect to the groups Y reactive therewith, for example the amino groups of an aminoalkylsilane (B)or the mercapto groups of a mercaptoalkylsilane (B).

[0040] The unsaturated monomer (Α') used in such pre-reaction with organosilicon compound (B) contains at least two groups of the formula R"-CH=CH-Z'- (III) or

R"-C≡C-Z'- (IV) and may preferably contain three or more groups of the formula

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV). The unsaturated monomer (Α') can for example be an acrylate ester of a polyhydric alcohol having 3 to 6 OH groups, for example pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate.

[0041] The organosilicon compound (B) used in such pre-reaction with unsaturated monomer (Α') preferably contains only a single aminoalkyl or mercaptoalkyl group to minimize crosslinking or branching reactions occurring before the unsaturated monomer (Α') and organosilicon compound (B) are reacted with the diene elastomer. The organosilicon compound (B) can for example be an aminoalkylsilane or mercaptoalkylsilane, particularly an aminoalkyltrialkoxysilane, an aminoalkylalkyldialkoxysilane or a

mercaptoalkyltrialkoxysilane. Preferred organosilicon compounds (B) for pre-reaction with unsaturated monomer (Α') thus include 3-aminopropyltrialkoxysilanes and 3- mercaptopropyltrialkoxysilanes. [0042] The reaction product of unsaturated monomer (Α') and organosilicon compound (B) may contain a mixture of products. For example when an ester of a polyhydric alcohol containing at least two, preferably at least three carboxylic ester groups of the formula -0-C(0>-CH=CH-R" is reacted with an aminoalkylsilane of the formula R * NH-A"- SiR a R'(3-a ) or a mercaptoalkylsilane of the formula HS-A"- SiR a R'<3-a) in such proportions that the carboxylic ester groups of the formula -0-C(0)-CH=CH-R" are present in molar excess with respect to the amino groups of the aminoalkylsilane or the mercapto groups of the mercaptoalkylsilane, the product comprises mainly at least one ester of a polyhydric alcohol, characterized in that the ester contains at least one carboxylic ester group of the formula -0-C(0)-CH=CH-R" and at least one carboxylic ester group of the formula:

-0-C(0)-CH 2 -CHR"-X'-A"-SiR a R , (3-a) Or

-0-C(0)-CH(CH 2 R")-X'-A"-SiRaR' ( 3-a) where R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, X' represents a -S- or -NR * - linkage, R * being H or an alkyl group having 1 to 4 carbon atoms or a group of the formula -A"-SiR a R'(3 -a ), A" represents a divalent organic group, R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive. The product may contain carboxylic ester groups of the formula -0-C(0)-CH=CH-R" and carboxylic ester group of the formula

C(0)-CH2-CHR"-X'-A"-SiRaR'(3-a) or -0-C(O^CH(CH 2 R")-X'-A"-SiR a R'(3-a) in varying proportions, depending on the exact molar ratio of starting reagents. This is illustrated below for the reaction of pentaerythritol tetraacrylate with a 3-aminopropyltrialkoxysilanes and 3- mercaptopropyltrialkoxysilane.

Si(OR) 3

(RO) 3 Si

(RO) 3 Si

(RO) 3 Si-

[0043] The temperature at which the diene elastomer and the unsaturated monomer (A) or (Α'), or the diene elastomer and the pre-reaction product of unsaturated monomer (Α') and organosilicon compound (B), are reacted in the diene elastomer in a typical temperature range of between 90°C and 200°C, preferably 120°C to 180°C.

• Preferably, the unsaturated monomer (A) or (Α') is present at 0.5 to 20.0% by

weight based on the diene elastomer.

[0044] If the organosilicon compound (B) contains hydrolysable groups, for example if (B) is a silane containing Si-bonded alkoxy groups, and the grafted polymer thus contains hydrolysable groups, these can react in the presence of moisture with hydroxyl groups present on the surface of many fillers and substrates, for example of minerals and natural products. The moisture can be ambient moisture or a hydrated salt can be added. Grafting of the diene elastomer with an organosilicon compound (B) according to the invention can be used to improve compatibility of the diene elastomer with fillers. The diene elastomer grafted with hydrolysable groups can be used as a coupling agent improving filler/polymer adhesion; for example polypropylene grafted according to the invention can be used as a coupling agent for unmodified polypropylene in filled compositions. The diene elastomer grafted with hydrolysable groups can be used as an adhesion promoter or adhesion interlayer improving the adhesion of a low polarity polymer such as polypropylene to surfaces. The hydrolysable groups can also react with each other in the presence of moisture to form Si-O-Si linkages between polymer chains.

[0045] The invention provides a process for grafting silane or silicone functionality onto a diene elastomer, characterized in that an unsaturated monomer (Α'), containing at least two groups of the formula R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) in which Z' represents a divalent linkage having an electron withdrawing effect with respect to the -CH=CH- or -C≡C- bond, and R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or -C≡C- bond, is reacted with an organosilicon compound (B) having a functional group Y which is reactive with the olefinic or acetylenic bond present in the group R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV), in such proportions that the reaction product contains on average at least one unsaturated moiety of the formula

R"-CH=CH-Z'- (III) or R"-C≡C-Z'- (IV) per molecule and at least one organosilicon moiety per molecule, and the said reaction product is reacted with the diene elastomer.

[0046] The invention extends to an ester of a polyhydric alcohol, characterized in that the ester contains at least one carboxylic ester group of the formula -0-C(0)-CH=CH-R", and at least one carboxylic ester group of the formula -0-C(0)-CH 2 -CHR"-X'-A'-SiR a R'(3-a) Or

-0-C(0)-CH(CH 2 R")-X'-A'-SiR a R' ( 3-a ) where R" represents hydrogen or a group having an electron withdrawing effect or any other activation effect with respect to the -CH=CH- or - C≡C- bond, X' represents a -S- or -NR * - linkage, R * being H or an alkyl group having 1 to 4 carbon atoms, A' represents a divalent organic group, R represents an alkoxy group having 1 to 4 carbon atoms; R' represents a hydrocarbyl group having 1 to 6 carbon atoms; and a has a value in the range 1 to 3 inclusive. Preferably, the ester contains at least one acrylate ester moiety and at least one 3-(trialkoxysilylalkylamino)propionate ester moiety.

Preferably, an ester of a polyhydric alcohol containing at least two carboxylic ester groups of the formula -0-C(0)-CH=CH-R" is reacted with an aminoalkylsilane of the formula R * NH-A'- SiR a R'(3-a) or a mercaptoalkylsilane of the formula HS-A'- SiR a R'( 3- a ) in such proportions that the carboxylic ester groups of the formula -O-C(O)- CH=CH-R" are present in molar excess with respect to the amino groups of the aminoalkylsilane or the mercapto groups of the mercaptoalkylsilane. The invention provides a composition comprising a diene elastomer and an ester as defined above.

[0047] The hydrolysable groups, for example silyl-alkoxy groups, react with each other in the presence of moisture to form Si-O-Si linkages between polymer chains even at ambient temperature, without catalyst, but the reaction proceeds much more rapidly in the presence of a siloxane condensation catalyst. Thus the grafted polymer can be crosslinked by exposure to moisture in the presence of a silanol condensation catalyst. The grafted polymer can be foamed by adding a blowing agent, moisture and condensation catalyst. Any suitable condensation catalyst may be utilised. These include protic acids, Lewis acids, organic and inorganic bases, transition metal compounds, metal salts and organometallic complexes.

[0048] Preferred catalysts include organic tin compounds, particularly organotin salts and especially diorganotin dicarboxylate compounds such as dibutyltin dilaurate, dioctyltin dilaurate, dimethyltin dibutyrate, dibutyltin dimethoxide, dibutyltin diacetate, dimethyltin bisneodecanoate, dibutyltin dibenzoate, dimethyltin dineodeconoate or dibutyltin dioctoate.

Alternative organic tin catalysts include triethyltin tartrate, stannous octoate, tin oleate, tin naphthate, butyltintri-2-ethylhexoate, tin butyrate, carbomethoxyphenyl tin trisuberate and isobutyltin triceroate. Organic compounds, particularly carboxylates, of other metals such as lead, antimony, iron, cadmium, barium, manganese, zinc, chromium, cobalt, nickel, aluminium, gallium or germanium can alternatively be used.

[0049] The condensation catalyst can alternatively be a compound of a transition metal selected from titanium, zirconium and hafnium, for example titanium alkoxides, otherwise known as titanate esters of the general formula Ti[OR 5 ] 4 and/or zirconate esters Zr[OR 5 ] 4 where each R 5 may be the same or different and represents a monovalent, primary, secondary or tertiary aliphatic hydrocarbon group which may be linear or branched containing from 1 to 10 carbon atoms. Preferred examples of R 5 include isopropyl, tertiary butyl and a branched secondary alkyl group such as 2,4-dimethyl-3-pentyl. Alternatively, the titanate may be chelated with any suitable chelating agent such as acetylacetone or methyl or ethyl acetoacetate, for example diisopropyl bis(acetylacetonyl)titanate or diisopropyl bis(ethylacetoacetyl)titanate. [0050] The condensation catalyst can alternatively be a protonic acid catalyst or a Lewis acid catalyst. Examples of suitable protonic acid catalysts include carboxylic acids such as acetic acid and sulphonic acids, particularly aryl sulphonic acids such as

dodecylbenzenesulphonic acid. A "Lewis acid" is any substance that will take up an electron pair to form a covalent bond, for example, boron trifluoride, boron trifluoride monoethylamine complex, boron trifluoride methanol complex, FeC , AICI3, ZnCI 2 , ZnBr 2 or catalysts of formula MR 4 f X g where M is B, Al, Ga, In or Tl, each R 4 is independently the same or different and represents a monovalent aromatic hydrocarbon radical having from 6 to 14 carbon atoms, such monovalent aromatic hydrocarbon radicals preferably having at least one electron-withdrawing element or group such as -CF 3 , -N0 2 or -CN, or substituted with at least two halogen atoms; X is a halogen atom; f is 1 , 2, or 3; and g is 0, 1 or 2; with the proviso that f+g =3. One example of such a catalyst is B(C 6 F 5 ) 3 .

[0051] An example of a base catalyst is an amine or a quaternary ammonium compound such as tetramethylammonium hydroxide, or an aminosilane. Amine catalysts such as laurylamine can be used alone or can be used in conjunction with another catalyst such as a tin carboxylate or organotin carboxylate.

[0052] The silane condensation catalyst is typically used at 0.005 to 1.0 by weight of the total composition. For example a diorganotin dicarboxylate is preferably used at 0.01 to 0.1 % by weight of the total composition.

[0053] Diene elastomer compositions according to the invention which are to be cured to a shaped rubber article generally contain a filler, particularly a reinforcing filler such as silica or carbon black. The filler is usually mixed with the elastomer in a non-productive thermo- mechanical mixing or kneading phase. In the present case when preparing a filled rubber composition, the elastomer; the unsaturated monomer (A) or (Α') and the silicon compound (B) can be reacted and then mixed with the filler, but the filler is preferably present during the reaction between the elastomer and the unsaturated-functional silicone resin. The elastomer, the unsaturated monomer (A) or (Α'), the silicon compound (B) and the filler can all be loaded to the same mixer and mixed while being heated, for example by thermo-mechanical kneading. Alternatively the filler can be pre-treated the silicon compound (B) and then mixed with the elastomer and the unsaturated monomer (A) or (Α'), preferably with heating. When the unsaturated-functional silicone resin is present during thermo-mechanical kneading of the diene elastomer and the filler, it reacts with the elastomer to form a modified diene elastomer and also acts as a coupling agent bonding the filler to the elastomer.

[0054] The filler is preferably a reinforcing filler. Examples of reinforcing fillers are silica, silicic acid, carbon black, or a mineral oxide of aluminous type such as alumina trihydrate or an aluminium oxide-hydroxide, or a silicate such as an aluminosilicate, or a mixture of these different fillers.

[0055] Use of the unsaturated monomer (A) or (Α') and the silicon compound (B) according to the invention is particularly advantageous in a curable elastomer composition comprising a filler containing hydroxyl groups, particularly in reducing the mixing energy required for processing the rubber composition and improving the performance properties of products formed by curing the rubber composition. The hydroxyl-containing filler can for example be a mineral filler, particularly a reinforcing filler such as a silica or silicic acid filler, as used in white tire compositions, or a metal oxide such as a mineral oxide of aluminous type such as alumina trihydrate or an aluminium oxide-hydroxide, or carbon black pre-treated with a alkoxysilane such as tetraethyl orthosilicate, or a silicate such as an aluminosilicate or clay, or cellulose or starch, or a mixture of these different fillers. [0056] The reinforcing filler can for example be any commonly employed siliceous filler used in rubber compounding applications, including pyrogenic or precipitated siliceous pigments or aluminosilicates. Precipitated silicas are preferred, for example those obtained by the acidification of a soluble silicate, e.g., sodium silicate. The precipitated silica preferably has a BET surface area, as measured using nitrogen gas, in the range of about 20 to about 600 m 2 /g, and more usually in a range of about 40 or 50 to about 300 m 2 /g. The BET method of measuring surface area is described in the Journal of the American

Chemical Society, Volume 60, Page 304 (1930). The silica may also be typically

characterized by having a dibutylphthalate (DBP) value in a range of about 100 to about 350 cm 3 /100 g, and more usually about 150 to about 300 cm 3 /100 g, measured as described in ASTM D2414. The silica, and the alumina or aluminosilicate if used, preferably have a CTAB surface area in a range of about 100 to about 220 m 2 /g (ASTM D3849). The CTAB surface area is the external surface area as evaluated by cetyl trimethylammonium bromide with a pH of 9. The method is described in ASTM D 3849. [0057] Various commercially available silicas may be considered for use in elastomer compositions according to this invention such as silicas commercially available from Rhodia with, for example, designations of Zeosil ® 1165MP, 1 115MP, or HRS 1200MP; 200MP premium, 80GR or equivalent silicas available from PPG Industries under the Hi-Sil trademark with designations Hi-Sil ® EZ150G, 210, 243, etc; silicas available from Degussa AG with, for example, designations VN3, Ultrasil ® 7000 and Ultrasil ® 7005, and silicas commercially available from Huber having, for example, a designation of Hubersil ® 8745 and Hubersil ® 8715. Treated precipitated silicas can be used, for example the aluminum-doped silicas described in EP-A-735088.

[0058] If alumina is used in the elastomer compositions of the invention, it can for example be natural aluminum oxide or synthetic aluminum oxide (Al 2 0 3 ) prepared by controlled precipitation of aluminum hydroxide. The reinforcing alumina preferably has a BET surface area from 30 to 400 m 2 /g, more preferably between 60 and 250 m 2 /g, and an average particle size at most equal to 500 nm, more preferably at most equal to 200 nm. Examples of such reinforcing aluminas are the aluminas A125, CR125, D65CR from Baikowski or the neutral, acidic, or basic Al 2 0 3 that can be obtained from the Aldrich Chemical Company. Neutral alumina is preferred. [0059] Examples of aluminosilicates which can be used in the elastomer compositions of the invention are Sepiolite, a natural aluminosilicate which might be obtained as PANSIL ® from Tolsa S.A., Toledo, Spain, and SILTEG ® , a synthetic aluminosilicate from Degussa GmbH. [0060] The hydroxyl-containing filler can alternatively be talc, magnesium dihydroxide or calcium carbonate, or a natural organic filler such as cellulose fiber or starch. Mixtures of mineral and organic fillers can be used, as can mixtures of reinforcing and non-reinforcing fillers. [0061] The filler can additionally or alternatively comprise a filler which does not have hydroxyl groups at its surface, for example a reinforcing filler such as carbon black and/or a non-reinforcing filler such as calcium carbonate. [0062] The reaction between the diene elastomer the unsaturated monomer (A) or (Α') and the silicon compound (B) can be carried out as a batch process or as a continuous process using any suitable apparatus. [0063] Continuous processing can be effected in an extruder such as a single screw or twin screw extruder. The extruder is preferably adapted to mechanically work, that is to knead or compound, the materials passing through it, for example a twin screw extruder. One example of a suitable extruder is that sold under the trade mark ZSK from Coperion Werner Pfeidener. The extruder preferably includes a vacuum port shortly before the extrusion die to remove any unreacted silane. The residence time of the diene elastomer and the unsaturated-functional silicone resin at above 100°C in the extruder or other continuous reactor is generally at least 0.5 minutes and preferably at least 1 minute and can be up to 15 minutes. More preferably the residence time is 1 to 5 minutes. [0064] A batch process can for example be carried out in an internal mixer such as a Banbury mixer or a Brabender Plastograph (Trade Mark) 350S mixer equipped with roller blades. An external mixer such as a roll mill can be used for either batch or continuous processing. In a batch process, the elastomer and the unsaturated-functional silicone resin are generally mixed together at a temperature above 100°C for at least 1 minute and can be mixed for up to 20 minutes, although the time of mixing at high temperature is generally 2 to 10 minutes.

[0065] The elastomer compositions are preferably produced using the conventional two successive preparation phases of mechanical or thermo-mechanical mixing or kneading ("non-productive" phase) at high temperature, followed by a second phase of mechanical mixing ("productive" phase) at lower temperature, typically less than 110°C, for example between 40°-100°C, during which the cross-linking and vulcanization systems are incorporated. [0066] During the non productive phase, the unsaturated monomer (A) or (Α') and the silicon compound (B), the diene elastomer and the filler are mixed together. Mechanical or thermo-mechanical kneading occurs, in one or more steps, until a maximum temperature of 1 10°-190°C is reached, preferably between 130°-180°C. When the apparent density of the reinforcing inorganic filler is low (generally the case for silica), it may be advantageous to divide the introduction thereof into two or more parts in order to improve further the dispersion of the filler in the rubber. The total duration of the mixing in this non-productive phase is preferably between 2 and 10 minutes.

[0067] Compositions comprising the modified elastomer produced by reaction with the unsaturated monomer (A) or (Α') and the silicon compound (B) according to the invention can be cured by various mechanisms. The curing agent for the modified elastomer can be a conventional rubber curing agent such as a sulfur vulcanizing agent. Alternatively the modified elastomer can be cured by a radical initiator such as a peroxide. Alternatively the modified elastomer can be cured by exposure to moisture in the presence of a silanol condensation catalyst. The hydrolysable silane groups grafted onto the elastomer can react with each other to crosslink the elastomer and/or can be further reacted with a polar surface, filler or polar polymer.

[0068] For many uses curing by a conventional sulfur vulcanizing agent is preferred.

Examples of suitable sulfur vulcanizing agents include, for example, elemental sulfur (free sulfur) or sulfur donating vulcanizing agents, for example, an amine disulfide, polymeric polysulfide or sulfur olefin adducts which are conventionally added in the final, productive, rubber composition mixing step. Preferably, in most cases, the sulfur vulcanizing agent is elemental sulfur. Sulfur vulcanizing agents are used in an amount ranging from about 0.4 to about 8% by weight based on elastomer, preferably 1.5 to about 3%, particularly 2 to 2.5%.

[0069] Accelerators are generally used to control the time and/or temperature required for vulcanization and to improve the properties of the vulcanized elastomer composition. In one embodiment, a single accelerator system may be used, i.e., primary accelerator.

Conventionally and preferably, a primary accelerator(s) is used in total amounts ranging from about 0.5 to about 4% by weight based on elastomer, preferably about 0.8 to about 1.5%. In another embodiment, combinations of a primary and a secondary accelerator might be used with the secondary accelerator being used in smaller amounts of about 0.05 to about 3% in order to activate and to improve the properties of the vulcanisate. Delayed action accelerators may be used which are not affected by normal processing temperatures but produce a satisfactory cure at ordinary vulcanization temperatures. Vulcanization retarders can also be used, e.g. phthalic anhydride, benzoic acid or cyclohexylthiophthalimide.

Suitable types of accelerators that may be used in the present invention are amines, disulfides, guanidines, thioureas, thiazoles, for example mercaptobenzothiazole, thiurams, sulfenamides, dithiocarbamates, thiocarbonates, and xanthates. Preferably, the primary accelerator is a sulfenamide. If a second accelerator is used, the secondary accelerator is preferably a guanidine, dithiocarbamate or thiuram compound.

[0070] In case the curing system is composed of sulphur, the vulcanization, or curing, of a rubber product such as a tire or tire tread is carried out in known manner at temperatures preferably between 130°-200°C, under pressure, for a sufficiently long period of time. The required time for vulcanization may vary for example between 2 and 30 minutes.

[0071] In one preferred procedure the diene elastomer the unsaturated monomer (A) or (Α') and the silicon compound (B) and possibly the filler are mixed together above 100°C in an internal mixer or extruder.

[0072] By way of example, the first (non-productive) phase is effected in a single thermomechanical step during which in a first phase the reinforcing filler, the unsaturated monomer (A) or (Α') and the silicon compound (B)and the elastomer are mixed in a suitable mixer, such as a conventional internal mixer or extruder, then in a second phase, for example after one to two minutes' kneading, any complementary covering agents or processing agents and other various additives, with the exception of the vulcanization system, are introduced into the mixer. A second step of thermomechanical working may be added in this internal mixer, after the mixture has dropped and after intermediate cooling to a temperature preferably less than 100°C, with the aim of making the compositions undergo complementary thermomechanical treatment, in particular in order to improve further the dispersion, in the elastomeric matrix, of the reinforcing inorganic filler. The total duration of the kneading, in this non-productive phase, is preferably between 2 and 10 minutes.

[0073] After cooling of the mixture thus obtained, the vulcanization system is then incorporated at low temperature, typically on an external mixer such as an open mill, or alternatively on an internal mixer (Banbury type). The entire mixture is then mixed

(productive phase) for several minutes, for example between 2 and 10 minutes.

[0074] Any other additives such as a grafting catalyst can be incorporated either in the "non productive" phase or in the productive phase.

[0075] The elastomer composition can be compounded with various commonly-used additive materials such as processing additives, for example oils, resins including tackifying resins, silicas, and plasticizers, fillers, pigments, fatty acid, zinc oxide, waxes, antioxidants and antiozonants, heat stabilizers, UV stabilizers, dyes, pigments, extenders and peptizing agents. [0076] Typical amounts of tackifier resins, if used, comprise about 0.5 to about 10% by weight based on elastomer, preferably 1 to 5%. Typical amounts of processing aids comprise about 1 to about 50% by weight based on elastomer. Such processing aids can include, for example, aromatic, naphthenic, and/or paraffinic processing oils. [0077] Typical amounts of antioxidants comprise about 1 to about 5% by weight based on elastomer. Representative antioxidants may be, for example, N-1 ,3- dimethylbutyl-N-phenyl- para-phenylenediamine, sold as "Santoflex 6-PPD" (trade mark) from Flexsys, diphenyl-p- phenylenediamine and others, for example those disclosed in The Vanderbilt Rubber Handbook (1978), Pages 344 through 346. Typical amounts of antiozonants also comprise about 1 to 5% by weight based on elastomer.

[0078] Typical amounts of fatty acids, if used, which can include stearic acid or zinc stearate, comprise about 0.1 to about 3% by weight based on elastomer. Typical amounts of zinc oxide comprise about 0 to about 5% by weight based on elastomer alternatively 0.1 to 5%.

[0079] Typical amounts of waxes comprise about 1 to about 5% by weight based on elastomer. Microcrystalline and/or crystalline waxes can be used. [0080] Typical amounts of peptizers comprise about 0.1 to about 1% by weight based on elastomer. Typical peptizers may for example be pentachlorothiophenol or

dibenzamidodiphenyl disulfide.

[0081] The modified elastomer composition containing a curing agent such as a

vulcanizing system is shaped and cured into an article. A rubber article is produced from a composition according to the invention and the filled elastomer composition is shaped and cured. Preferably, the composition contains a suitable curing system selected from sulphur, peroxide or a sulphur compound. In another preferred embodiment, the composition is cured by moisture.The moisture cure can be accelerated by a hydrolysis/condensation catalyst. [0082] The elastomer composition can be used to produce tires (tyres), including any part thereof such as the bead, apex, sidewall, inner liner, tread or carcass. The elastomer composition can alternatively be used to produce any other engineered rubber goods, for example bridge suspension elements, hoses, belts, shoe soles, anti seismic vibrators, and dampening elements. The elastomer composition can be cured in contact with reinforcing elements such as cords, for example organic polymer cords such as polyester, nylon, rayon, or cellulose cords, or steel cords, or fabric layers or metallic or organic sheets.

[0083] In the case of a passenger car tire, the preferred starting diene elastomer is for example a styrene butadiene rubber (SBR), for example an SBR prepared in emulsion ("ESBR") or an SBR prepared in solution ("SSBR"), or an SBR/BR, SBR/NR (or SBR/IR), alternatively BR/NR (or BR/IR), or SIBR (isoprene-butadiene-styrene copolymers), IBR (isoprene-butadiene copolymers), or blends (mixtures) thereof. In the case of an SBR elastomer, in particular an SBR having a styrene content of between 20% and 30% by weight, a content of vinyl bonds of the butadiene fraction of between 15% and 65%, and a content of trans-1 ,4 bonds of between 15% and 75% is preferred. Such an SBR copolymer, preferably an SSBR, is possibly used in a mixture with a polybutadiene (BR) having preferably more than 90% cis-1 ,4 bonds. [0084] In the case of a tire for a heavy vehicle, the elastomer is in particular an isoprene elastomer; that is an isoprene homopolymer or copolymer, in other words a diene elastomer selected from the group consisting of natural rubber (NR), synthetic polyisoprenes (IR), the various isoprene copolymers or a mixture of these elastomers. Of the isoprene copolymers, mention will be made in particular of isobutene-isoprene copolymers (butyl rubber-IIR), isoprene-styrene copolymers (SIR), isoprene-butadiene copolymers (BIR) or isoprene- butadiene-styrene copolymers (SBIR). This isoprene elastomer is preferably natural rubber or a synthetic cis-1 ,4 polyisoprene; of these synthetic polyisoprenes, preferably

polyisoprenes having a content (mole %) of cis-1 ,4 bonds greater than 90%, more preferably still greater than 98%, are used. For such a tire for a heavy vehicle, the elastomer may also be constituted, in its entirety or in part, of another highly unsaturated elastomer such as, for example, a SBR or a BR elastomer.

[0085] When the elastomer composition is for use as a tire sidewall, the elastomer may comprise at least one essentially saturated diene elastomer, in particular at least one EPDM copolymer, which may for example be used alone or in a mixture with one or more of the highly unsaturated diene elastomers.

[0086] The modified elastomer composition containing a vulcanizing system can for example be calendered, for example in the form of thin slabs (thickness of 2 to 3 mm) or thin sheets of rubber in order to measure its physical or mechanical properties, in particular for laboratory characterization, or alternatively can be extruded to form rubber profiled elements used directly, after cutting or assembling to the desired dimensions, as a semi-finished product for tires, in particular as treads, plies of carcass reinforcements, sidewalls, plies of radial carcass reinforcements, beads or chaffers, inner tubes or air light internal rubbers for tubeless tires.

[0087] As an alternative to curing by a sulfur vulcanizing system, the modified elastomer composition can be cured by a peroxide. Examples are di(tert-butyl)peroxide; t-butylcumyl peroxide; dicumyl peroxide; benzoyl peroxide; 1 ,1'-di(t-butylperoxy)-3,3,5- trimethylcyclohexane; 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne; 2,5-dimethyl-2,5-di(t- butylperoxy)hexane; a,a'-di(t-butylperoxy)-m/p-diisopropylbenzene; and n-butyl-4,4'-di(tert- butylperoxy)valerate. [0088] This invention relates to the use of the unsaturated monomer (A) or (Α') and the silicon compound (B) to graft to diene polymer to help the grafting. However, vulcanization can still be done using peroxides. Heat or UV radiation can be used to vulcanise the rubber in order to activate the peroxide. Heat activation of the peroxide is the preferred way, for example with temperature from 100 to 200°C for a time comprised between 1 to 90 minutes, preferably 5 to 20 minutes.

[0089] A second alternative to sulfur and peroxide cure is the use of the alkoxysilane groups of the obtained grafted polymer. If the grafted elastomer is crosslinked by exposure to moisture in the presence of a silanol condensation catalyst, any suitable condensation catalyst may be used. These include protic acids, Lewis acids, organic and inorganic bases, transition metal compounds, metal salts and organometallic complexes. Preferred condensation catalysts are those hereinbefore described. [0090] The silane condensation catalyst is typically used at 0.005 to 1.0% by weight based on the modified diene elastomer. For example a diorganotin dicarboxylate is preferably used at 0.01 to 0.1% by weight based on the elastomer. [0091] When curing a modified diene elastomer by exposure to moisture, the modified elastomer is preferably shaped into an article and subsequently crosslinked by moisture. In one preferred procedure, the silanol condensation catalyst can be dissolved in the water used to crosslink the grafted polymer. For example an article shaped from grafted polyolefin can be cured by water containing a carboxylic acid catalyst such as acetic acid, or containing a diorganotin carboxylate.

[0092] Alternatively or additionally, the silanol condensation catalyst can be incorporated into the modified elastomer before the modified elastomer is shaped into an article. The shaped article can subsequently be crosslinked by moisture. The catalyst can be mixed with the diene elastomer before, during or after the grafting reaction.

[0093] A silanol condensation catalyst can be used in addition to other curing means such as vulcanization by sulphur. In this case, the silanol condensation catalyst can be incorporated either in the "non productive" phase or in the productive phase of the preferred vulcanization process described above.

[0094] When curing is done using alkoxysilane groups of the grafted elastomer, care should be taken when forming a cured elastomer article to avoid exposure of the silane and catalyst together to moisture, or of the composition of silane-modified elastomer and catalyst to moisture before its final shaping into the desired article.

[0095] The modified diene elastomer according to the invention has improved adhesion both to fillers mixed with the elastomer and silane during the grafting reaction and to substrates to which the modified diene elastomer is subsequently applied. Improved adhesion to fillers results in better dispersion of the fillers during compounding. Substrates to which the modified diene elastomer is applied include metal cords and fabrics and organic polymer cords and fabrics which are incorporated into the structure of a finished article, for example a tire, made from the modified diene elastomer. Improved adhesion to such substrates leads to a finished article having improved mechanical and wear properties. [0096] The ability of the unsaturated monomer (A) or (Α') and the silicon compound (B) of the invention to react with a diene elastomer allows formation of a modified elastomer, especially modified natural rubber, without polymer degradation, leading to improved rubber performance, for example improved mechanical properties and/or resistance to thermal degradation, compared to a diene elastomer grafted in the presence of a free radical initiator such as peroxide. When the modified elastomer is used to manufacture tire treads, improved mechanical properties can give improved tire properties such as decreased rolling resistance, better tread wear and improved wet skid performance. Examples 1 and 2

[0097] Rubber goods were prepared according to the procedure described below for example 1 and comparative examples C1 and C2, using the ingredients described below. The amounts expressed in parts per hundred parts of rubber (phr) are described in table 1.

• NR SMR 10, CV60 - Natural rubber Standard Malaysian Rubber, purity grade 10, Constant viscosity (CV) 60 m.u. ( ooney unit)

• Silica - Zeosil ® 1165MP from Rhodia

· Silane 1 - γ-acryloxypropyltriethoxysilane from Dow Corning

• Silane 2- N-phenylaminopropyltrimethoxysilane from Gelest

• PETA - Pentaeritrytol-tetraacrylate from Sigma Aldrich

• ACST - Stearic Acid

• ZnO - Zinc Oxide

· 6PPD - N-1 ,3- dimethylbutyl-N-phenyl-para-phenylenediamine ("Santoflex ® 6-PPD")

• S - Elemental sulfur

• CBS - N-cyclohexyl-2-benzothiazyl sulfenamide ("Santocure ® CBS" from Flexsys)

• DPG - Diphenylgunaidine from Flexsys

• N234 - Conventional carbon black according to ASTM D1765

[0098] Comparative example C2 was a standard natural rubber formulation using acryloxypropyltriethoxysilane as described in WO2010/125123 and WO2010/125124.

[0099] The comparative example C1 was a standard natural rubber formulation for tire treads using carbon black filler. [0100] In the following example N-phenylaminopropyltrimethoxysilane and PETA were premixed together before being introduced into the rubber formulation. A simple physical blend was done to avoid any pre-reaction; difference between example 1 , 2 and 3 was the ratio between PETA and Silane 3, a ratio of 1 :3 corresponded to 1 molecule of PETA for 3 molecules of Silane 3.

Table 1

[0101] During a first non-productive phase, the reaction of the natural rubber, the silica and silane in presence of peroxides was carried out using thermomechanical kneading in a Banbury mixer. The procedure was as shown in Table 2, which indicates the time of addition of various ingredients. The temperature at the end of mixing was measured inside the rubber after dumping it from the mixer.

Table 2

[0102] The maximum temperature reached in the mixer was 165°C for all rubber compound. Rubber was then passed through the mil until a smooth sheet was obtained. [0103] During a second non-productive phase stearic acid, Zinc Oxid and 6PPD were added as shown in table 3: Table 3

[0104] The natural rubber composition thus produced was milled on a two-roll mill at a temperature of about 70°C during which milling the curing agents were added (productive phase). The mixing procedure for the productive phase is shown in Table 4.

Table 4

[0105] The modified rubber sheet produced was tested as follows. The results of the tests are shown in Table 5 below.

[0106] The rheometry measurements were performed at 160° C using an oscillating chamber rheometer (i.e., Advanced Plastic Analyzer) in accordance with Standard ISO 3417:1991 (F). The change in rheometric torque over time describes the course of stiffening of the composition as a result of the vulcanization reaction. The measurements were processed in accordance with Standard ISO 3417: 1991 (F). Minimum and maximum torque values, measured in deciNewtonmeter (dNm) are respectively denoted ML and MH time at α% cure (for example 5%) is the time necessary to achieve conversion of a% (for example 5%) of the difference between the minimum and maximum torque values. The difference, denoted MH-ML, between minimum and maximum torque values was also measured. In the same conditions the scorching time for the rubber compositions at 160°C was determined as being the time in minutes necessary to obtain an increase in the torque of 2 units, above the minimum value of the torque (Time@2dNm scorch S').

[0107] The tensile tests were performed in accordance with ISO Standard IS037:1994(F) using tensile specimen ISO 37 - type 2. The nominal stress (or apparent stresses, in MPa) at 10% elongation (M10), 100% elongation (M100) and elongation (M250 or M300) were measured at 10%, 100% and 250% or 300% of elongation. Breaking stresses (in MPa) were also measured. Elongation at break (in %) was measured according to Standard ISO 37. High values of Elongation at break are preferred. Preferably the Elongation at break was at least 300%. All these tensile measurements were performed under normal conditions of temperature and relative humidity in accordance with ISO Standard ISO 471. The ratio of M300 to M 100 correlates with tread wear resistance of a tire made from the rubber composition, with an increase in M300/M100 ratio indicating potential better tread wear resistance. [0108] The dynamic properties were measured on a viscoanalyser (Metravib VA4000), in accordance with ASTM Standard D5992-96.

Strain sweep: The response of a sample of vulcanized composition (thickness of 2.5 mm and a cross-section of 40 mm 2 ), subjected to an alternating single sinusoidal shearing stress, at a frequency of 10 Hz, under a controlled temperature of 55° C was recorded. Scanning is performed at amplitude of deformation of 0.1 to 50% the maximum observed value of the loss factor tan d is recorded, the value being denoted tan δ 6%. The tan δ 6% value is well correlated to the rolling resistance of the tire, the lower the tan δ 6% the lower the rolling resistance is, the better the tire performance will be. GO is the elastic modulus measured at very low strain, when the behaviour is linear with the stress. G' max is the elastic modulus at 50% strain. Dynamical properties have been recorded after a first strain sweep (GO) from 0.1 to 50%, then the second strain sweep from 50% to 0.1% has been also recorded. The difference between the modulus at first strain sweep and the modulus after the return to low strain (GO return) is denoted AGO which is well correlated to the handling stability of the tire under stress. The difference between GO return and G' max after the second strain sweep is denoted AG' return. The tan δ 6%, second strain sweep value corresponds to the maximum of the loss factor tan (δ) during the second strain sweep. A reduction in both tan δ 6% and tan δ 6%, second strain sweep is well correlated to a decrease in the rolling resistance of a tire manufactured from the rubber composition.

Temperature sweep: The response of a sample of vulcanized composition

(thickness of 2.5 mm, height of 14 mm and length of 4.0 mm), subjected to an alternating single sinusoidal shearing stress, at a frequency of 10 Hz, under a controlled displacement of 1.25 micron. The sample was placed at room

temperature and cooled down to -100°C with a rate of 5°C/min. The temperature was then stabilised at -100°C for 20 minutes to allow the sample to be at an equilibrium temperature state. The temperature was then increased up to 100°C at a rate of 5°C/min. The loss factor and the stiffness, giving the modulus and the tan (δ). The tan δ max and/or the value at 0°C (tan δ o°c) is related to the wet skid performances. An increase in the tan δ max and in the tan (δ) value at 0°C (tan δ 0 -c) is indicative of improved wet skid performance. The Shore A hardness was measured according to ASTM D2240-02b.

Table 5

[0110] Shore A and ML1 +4 value for example 1 and 2 were in a good range as required by the application.

[0111] The strain sweep results for example 1 and 2 showed a reduction in Tan δ 6%, second strain sweep compared to the conventional carbon black formulation in comparative example C1 and was close to comparative example C2. This is associated with a decrease of the rolling resistance of a tire made from the corresponding rubber composition.

[0112] The results of tan value during the temperature sweep for example 1 and 2 was increased compared to comparative example C1 indicating improved wet skid performance of tires made from the rubber compositions of example 1 and 2. [0113] The physical properties, e.g., M250/M100 or M300/M100 ratio when available, of example 1 or 2 were increased compared to comparative examples C1 and similar to the one from comparative example C2, indicating better tread wear resistance.

[0114] Example 1 and 2 showed increase modulus M250 than comparative example C1. Based on this and all previous results it is clear that in-situ silane generation using a pre- blend of PETA and silane 3 showed advantages over comparative example C1 based on carbon black similar to advantages seen in comparative example C2.

Examples 3, 4 and 5

[0115] Rubber composition of example 3, 4 and 5, and comparative example C1 a were prepared according to the same procedure as for examples 1 and 2, using the ingredients described in examples 1 and 2 in the amounts described in table 6.

[0116] As for example 1 and 2, PETA and phenylaminopropyltrimethoxysilane were premixed together before being introduced into the rubber formulation. A simple physical blend was done to avoid any pre-reaction; difference between example 1 , 2 and 3 is the ratio between PETA and Silane 3, a ratio of 1 :3 corresponds to 1 molecule of PETA for 3 molecules of Silane 3.

Table 6

[0117] Properties were as measured for example 1 and 2. Results are gathered in table 7.

Table 7

Example C1 3 4 5

Mooney Viscosity @100°C

Mmax (m.u.) 49 68 58 52 L1+4 (m.u.) 35 43 43 43

Rheometer@160°C

ML(dNm) 1,1 1,0 1,0 1,0

MH (dNm) 16,0 13,6 13,5 13,5

Time@5% cure S' (min) 3,2 6,6 6,7 6,7

Time@95% cure S' (min) 7,7 13,2 13,2 12,9

Time@2 dNm scorch S' (min) 4,0 8,0 8,1 8,1

MH-ML (dNm) 15,0 12,7 12,5 12,5

Dynamic properties, strain sweep @55°C, simple shear

G" o (Pa) 6,3 2,2 2,1 2,0

G'o return ( a) 5,2 1,9 1,8 1,6

AGO (Pa) 1,1 0,3 0,3 0,3

G'max (Pa) 1,2 1,2 1,1 1,0

AG' (Pa) 5,1 1,0 1,0 1,0

Tan δ 6% 0,20 0,10 0,10 0,09

Tan δ 6%, second strain sweep 0,21 0,09 0,09 0,09

Dynamic properties, T°C sweep

an δ max 0,84 1,16 1,15 1,16

Physical properties

M10(MPa) 0,7 0,6 0,6 0,6

M100 (MPa) 3,7 3,6 3,5 3,5

M250 (Mpa) 14,4 17,2 16,4 16,6

M300 (MPa) 18,5 22,4 21,5 21,5

M250/M100 3,9 4,8 4,7 4,7

M300/M100 5,0 6,2 6,2 6,1

Tensile break (MPa) 29,1 25,3 24,9 29,0

Elong max (%) 445 330 336 386

Shore A 61 62 61 61 [0118] Shore A and ML1 +4 value for example 3, 4 and 5 were in a good range as required by the application.

[0119] The strain sweep results for example 3, 4 and 5 showed a reduction in Tan δ 6%, second strain sweep compared to the conventional carbon black formulation in comparative example C1 a. This is associated with a decrease of the rolling resistance of a tire made from the corresponding rubber composition.

[0120] The results of tan 5 ma x value during the temperature sweep for example 3, 4 and 5 was increased compared to comparative example C1a indicating improved wet skid performance of tires made from the rubber compositions of example 3,4 and 5..

[0121] The physical properties, e.g., M300/M100 ratio, of example 3, 4 and 5 were increased compared to comparative examples C1a indicating better tread wear resistance.

[0122] Example 3, 4 and 5 showed increase modulus M300 than comparative example C1 a. Based on this and all previous results it was clear that in-situ silane generation using a pre-blend of PETA and silane 3 showed advantages over comparative example C1a. This is also indicating better tread wear resistance.

Examples 6

[0123] Rubber composition of example 6, and comparative example C1b and C2a were prepared according to the same procedure as for examples 1 and 2, using the ingredients described in examples 1 and 2 in the amounts described in table 8.

[0124] As for example 1 and 2 PETA and phenylaminopropyltrimethoxysilane were not premixed together before being introduced into the rubber formulation. Table 8

[0125] Properties were as measured for example 6. Results are gathered in table 9.

Table 9

[0126] ML1 +4 value for example 3, 4 and 5 were in a good range as required by the application.

[0127] The strain sweep results for example 6 showed a reduction in Tan δ 6%, second strain sweep compared to the conventional carbon black formulation in comparative example C1a and was similar to comparative example C2a. This is associated with a decrease of the rolling resistance of a tire made from the corresponding rubber composition.

[0128] The results of tan 8 max value during the temperature sweep for example 6 was increased compared to comparative example C1a indicating improved wet skid performance of tires made from the rubber compositions of example 6 and was comparable to

comparative example C2b.

[0129] The physical properties, e.g., M300/M100 ratio, of example 6 were increased compared to comparative examples C1a indicating better tread wear resistance.

[0130] Example 6 showed increase modulus M300 than comparative example C1a. Based on this and all previous results it is clear that in-situ silane generation using PETA and silane 3 showed advantages over comparative example C1a. This was also indicating better tread wear resistance.