Coalescents

[0001] This invention relates to the use of compounds derived from malic acid and other substituted diacids as coalescents, e.g. in water based decorative latex paints.

BACKGROUND

[0002] Coalescents are compounds which promote the formation of a uniform film upon application of a latex to a surface. When a latex containing a coalescent is deposited onto a surface, the coalescent softens the polymer particles in order to allow them to fuse (or coalesce) with each other. This contributes to their inter diffusion and increases the uniformity of the film. As the carrier solvent begins to evaporate, the volume of the wet coating layer begins to be reduced and the polymer particles begin to touch and loose shape. As the process goes on, agglomeration and inter-diffusion occurs and the dispersion inverts itself in the sense that the bulk of the film is a solid in which a minor component is now the original dispersion liquid, i.e. carrier solvent. The film forms and the coalescent slowly evaporates leaving a dry, hard polymer film.

[0003] Many market leading coalescents are based on ethylene and propylene glycol ethers (e.g. dipropylene glycol n-butyl ether and ethylene glycol monophenyl ether;).

These coalescents tend to release odour and volatile organic chemicals (VOCs), however regulatory legislation is driving a need for coalescents which release less odour and fewer VOCs.

[0004] Other coalescents which are currently available, such as 2,2,3-trimethyM ,3- pentanediol monoisobutyrate () and 2,2,3-trimethyl-1 ,3-pentanediol diisobutyrate (), are not themselves odour free and can react to produce odourous by-products when applied to a surface in a latex.

[0005] Certain compounds used in the methods of the invention are derived from malic acid, a readily available starting material. Other substituted diacids, e.g. 2-methylglutaratic acid are likewise readily available.

[0006] A good coalescent generally interacts well with both the surface and the inner portions of the polymer particles. They generally also have low water solubility and low volatility. Low volatility may be linked to improved hardness characteristics of the resultant films. In any event, many countries legislation requires coalescents in products to have low volatility and odour. Coalescents generally allow or encourage the paint to undergo phase change at the optimum development stage and should provide a film which is resistant to wet abrasion. Coalescents generally are resistant to hydrolysis at or around neutral pH, thus staying intact during film formation, but are nevertheless fully biodegradable. The compounds of the invention typically exhibit some or all of these properties. [0007] It is an aim of certain embodiments of the invention to provide coalescents which are present in a reduced residual amount in formed films. Conversely, it is an aim of certain embodiments to provide coalescents that can chemically bind to the polymer (possibly reducing VOC emissions). It is an aim of certain embodiments to provide coalescents that.can bind to certain polymer(s), thus improving the properties of the film (e.g. making the film harder).

[0008] It is an aim of certain embodiments of the invention to provide coalescents which have low or zero odour. Likewise, it is an aim of certain embodiments of the invention to provide coalescents which have low or zero emissions and/or low or very low toxicity.

[0009] It is an aim of certain embodiments of the invention to produce coalescents having a low VOC rating, e.g. one which meets or exceeds one or more national or international standards at 1 January 2016. It is an aim of certain embodiments of the invention to provide coalescents which have a lower VOC rating than other compounds that have equivalent volatility, e.g. because the coalescent cross-links or otherwise chemically binds to the polymer.

[0010] It is an aim of certain embodiments of the invention to provide coalescents which exhibit improved coalescent efficacy relative to prior art coalescents. Thus, film forming compositions of the invention may have lower minimum film forming temperatures than prior art compositions. Thus, film forming compositions of the invention may form harder films than prior art compositions. Thus, film forming compositions of the invention may form less tacky films than prior art compositions. The compounds of the invention may exhibit similar or even reduced coalescent efficacy relative to prior art coalescents but offer other benefits, e.g. they are more readily prepared or comply with legislative requirements in certain countries.

[0011] It is an aim of certain embodiments of the invention to provide coalescents which provide an effective coalescent effect when used in lower concentrations than existing products.

[0012] Certain embodiments of the invention satisfy some or all of the above aims.

BRIEF SUMMARY OF THE DISCLOSURE

[0013] In a first aspect of the invention is provided a film forming composition comprising: a polymer and at least one compound of formula (I), or a salt thereof:

(I), wherein R ¹ and R ³ are each independently at each occurrence selected from H, C ₁ -C25- alkyl, Ci-C ₂₅ -haloalkyl, C ₂ -C ₂ 5-alkenyl, C2-C25 alkynyl, (CR ⁴ R ⁴ ) _m -aryl and (CR ⁴ R ⁴ ) _m - cycloalkyl;

n is integer selected from 1 and 2;

X is independently at each occurrence selected from: Ci-C4-alkyl and OR ² ;

R ² is independently at each occurrence selected from: H, C(0)Ci-C25-alkyl, C(0)Ci-C25- haloalkyl,C(0)C ₂ -C ₂ 5-alkenyl, C(0)C ₂ -C ₂ 5-alkynyl, C(0)(CR ⁴ R ⁴ ) _m -aryl, C(0)(CR ⁴ R ⁴ ) _m - cycloalkyl; C(0)(CR ⁴ =CR ⁴ )-aryl, Ci-C ₂ 5-alkyl, Ci-C ₂ 5-haloalkyl, C ₂ -C ₂ 5-alkenyl and C ₂ -C25- alkynyl;R ⁴ is independently at each occurrence selected from: H, F, Ci-C4-alkyl and CF3; m is an integer independently selected from: 0, 1 , 2, 3, 4 and 5;

wherein each of the aforementioned alkyl, alkenyl, alkynyl, cycloalkyi and aryl (e.g. phenyl) groups, are optionally substituted, where chemically possible, by 1 to 3 substituents which are each independently at each occurrence selected from the group consisting of: oxo, fluoro, C0 ₂ R ^a , C(0)R ^a , CONR ^a R ^a , Ci-C ₄ -alkyl, C ₂ -C ₄ -alkenyl, C ₂ -C ₄ -alkenyl, and C1-C4- haloalkyl; wherein R ^a is independently at each occurrence selected from C ₁ -C4 alkyl; provided that at least one of R ¹ , R ² and R ³ is not H.

[0014] In an embodiment, , the compound of formula (I) may be a compound of formula

(II):

wherein R ¹ , R ² and R ³ are as defined above for formula (I);

[0015] Coalescents (i.e. the compounds of formula (I)) used in the compositions of the invention find particular application in latex based paints, which are typically emulsions of polymer in water, but can also be used in inks, varnishes, adhesives, coatings, fillers etc.

[0016] Thus, the composition may be a latex. A 'latex' is a colloidal dispersion of polymer particles in a liquid. The latex may be a latex paint, e.g. a decorative latex paint. The latex may be water based, i.e. the liquid may be water or it may be an aqueous solution. Thus, the latex may be a water based latex paint, e.g. a water based decorative latex paint.

[0017] The coalescent may be present in an amount less than 5% by weight of the latex composition, e.g. less than 3%. The coalescent may be present in an amount greater than 0.1 % by weight of the composition, e.g. greater than 1 % by weight of the composition. [0018] The film forming composition may comprise two or more compounds of formula (I). More typically, however, it will contain a single compound of formula (I).

[0019] In a second aspect of the invention is provided the use of a compound of formula (I) as a coalescent

[0020] The coalescent may be used in a latex, e.g. a latex paint.

[0021] In a third aspect of the invention is provided a method of providing a film having modified properties relative to the properties of an unmodified film, the method comprising: a) either providing an unmodified film-forming composition comprising a liquid and a polymer and adding a compound of formula (I) to the composition to form a coalescent composition; or

taking a compound of formula (I) and admixing it with either the liquid or the polymer component of an unmodified film-forming composition comprising a liquid and a polymer, and then combining the resulting mixture with the other of the liquid or the polymer to form a coalescent composition; and

b) applying the coalescent composition to a substrate so that the composition can dry to form a film.

[0022] In any of the first to third aspects of the invention, the compound of formula (I) may be a compound of formula (II):

[0023] wherein R ¹ , R ² and R ³ are as defined above for formula (I)

[0024] In any of the first to third aspects of the invention, the compound of formula (I) may be a compound of formula (III):

wherein R ¹ and R ³ are as defined above for formula (I).

[0025] It may be that R ¹ and R ³ are the same. Such compounds are easier to manufacture. [0026] I n any of the first to third aspects of the invention, the compound of formula (I) may be a compound of formula (IV):

wherein R ^1a is the same at each occurrence and is C2-C6-alkyl.

[0027] I n any of the first to third aspects of the invention, the compound of formula (I) may be a compound of formula (V):

wherein R ¹ and R ³ are as defined above for formula (I); and wherein R ⁵ is methyl or ethyl.

[0028] It may be that R ¹ and R ³ are the same. Such compounds are easier to manufacture.

[0029] I n any of the first to third aspects of the invention, the compound of formula (I) may be a compound of formula (VI):

wherein R ^1a is the same at each occurrence and is C2-C6-alkyl and wherein R ⁵ is methyl or ethyl.

[0030] The following embodiments apply to compounds of any of formulae (I) to (VI). These embodiments are independent and interchangeable. Any one embodiment may be combined with any other embodiment, where chemically allowed. I n other words, any of the features described in the following embodiments may (where chemically allowable) be combined with the features described in one or more other embodiments. I n particular, where a compound is exemplified or illustrated in this specification, any two or more of the embodiments listed below, expressed at any level of generality, which encompass that compound may be combined to provide a further embodiment which forms part of the present disclosure.

[0031] X may be OR ² . X may be Ci-C4-alkyl. Thus, X may be methyl. Likewise, X may be ethyl. [0032] n may be 1. n may be 2.

[0033] It may be that X is OR ² and n is i

[0034] Alternatively, it may be that X is Ci-C4-alkyl and n is 2.

[0035] It may be that R ² is independently a group selected from H, C(0)Ci-C25-alkyl, C(0)Ci-C ₂ 5-haloalkyl,C(0)C ₂ -C ₂ 5-alkenyl, C(0)C ₂ -C ₂ 5-alkynyl, C(0)(CR ⁴ R ⁴ ) _m -aryl, C(0)(CR ⁴ R ⁴ )m-cycloalkyl; C(0)(CR ⁴ =CR ⁴ )-aryl, Ci-C ₂₅ -alkyl. It may be that R ² is independently a group selected from Ci-C ₂ 5-haloalkyl, C ₂ -C ₂ 5-alkenyl and C ₂ -C ₂ 5-alkynyl. It may be that R ² is independently a group selected from H, C(0)Ci-C ₂ s-alkyl, C(0)C ₂ -C ₂ s- alkenyl, C(0)C ₂ -C ₂₅ -alkynyl. Thus, R ² may be C(0)Ci-C ₂₅ -alkyl (e.g. C(O)Ci-Ci ₀ -alkyl or C(0)Ci-C ₈ -alkyl. R ² may be acetyl.

[0036] Preferably, however, R ² is H.

[0037] Without wishing to be bound by theory, it is believed that compounds having a free hydroxyl group (e.g. those in which R ² is H) can participate in cross-linking reactions with the polymer(s) when used as coalescents in certain polymer systems. Such cross- linking can improve the properties of the resultant coating, e.g. making it harder.

[0038] Furthermore, compounds which are capable of chemically binding to the polymer, either through a cross-linking process or by otherwise forming covalent bonds with the polymer chains in a given polymer system, can provide fewer VOC emissions relative to other compounds with similar volatilities but which don't chemically bind to the polymer. It is believed that compounds having a free hydroxyl group (e.g. those in which R ² is H) exhibit this benefit in certain polymer systems.

[0039] R ¹ may be selected from Ci-C ₈ -alkyl, Ci-C ₈ -haloalkyl, C ₂ -C ₈ -alkenyl, C ₂ -C ₈ alkynyl, aryl, cycloalkyl, and heterocycloalkyl. In a preferred embodiment, R ¹ is selected from d-Cs-alkyl, C ₂ -C ₈ -alkenyl and C ₂ -C ₈ alkynyl. Preferably, R ¹ is C ₂ -C ₈ alkyl. R ¹ may be selected from ethyl, n-propyl, / ^' -propyl, 7-butyl, / ^' so-butyl, sec-butyl, n-pentyl, / ^' -pentyl, t- pentyl. n-hexyl, 2-ethylhexyl. R ¹ may be C3-Cs-alkyl, e.g. C3-C4-alkyl or C4-C5-alkyl. R ¹ may be selected from isopropyl, n-butyl and isobutyl. R ¹ may be selected from isopropyl and isobutyl. R ¹ may be selected from isobutyl and n-butyl. R ¹ may be isobutyl. In these embodiments, R ¹ is preferably unsubstituted.

[0040] R ³ may be selected from Ci-C ₈ -alkyl, Ci-C ₈ -haloalkyl, C ₂ -C ₈ -alkenyl, C ₂ -C ₈ alkynyl, aryl, cycloalkyl, and heterocycloalkyl. In a preferred embodiment, R ³ is selected from Ci-C ₈ -alkyl, C ₂ -C ₈ -alkenyl and C ₂ -C ₈ alkynyl. Preferably, R ³ is C ₂ -C ₈ alkyl. R ³ may be selected from ethyl, n-propyl, / ^' -propyl, 7-butyl, / ^' so-butyl, sec-butyl, n-pentyl, / ^' -pentyl, t- pentyl. n-hexyl, 2-ethylhexyl. R ³ may be C3-Cs-alkyl, e.g. C3-C4-alkyl or C4-Cs-alkyl. R ³ may be selected from isopropyl, n-butyl and isobutyl. R ³ may be selected from isopropyl and isobutyl. R ³ may be selected from isobutyl and n-butyl. R ³ may be isobutyl. In these embodiments, R ³ is preferably unsubstituted.

[0041] R ^1a may be C ₃ -C ₅ -alkyl, e.g. C ₃ -C ₄ -alkyl or C ₄ -C ₅ -alkyl. R ^1a may be selected from isopropyl, n-butyl or isobutyl. R ^1a may be selected from isopropyl and isobutyl. R ^1a may be selected from isobutyl and n-butyl. R ^1a may be isobutyl. In these embodiments, R ^1a is preferably unsubstituted.

[0042] R ⁵ may be methyl. Likewise, R ⁵ may be ethyl.

[0043] The compound may be selected from diisopropyl malate, diisobutyl malate, di-n- butyl malate and diisobutyl-2-methylglutarate.

[0044] The compound may be diispropyl malate.

[0045] The compound may be diisobutyl-2-methylglutarate.

[0046] The compound of formula (I) comprises at least one chiral centre, namely the carbon to which the OR ² group is derived. It may be that the compound has said chiral centre entirely in the (R)-configuration, it may be that the compound has said chiral centre entirely in the (S)-configuration or it may be that the compounds is a mixture of compounds having said chiral centre in the (R)-configuration and those having said centre in the (S)- configuration. Typically, the carbon to which the OR ² group is derived will be the only chiral centre in the compound. Thus, it may be that the compound is substantially present as the (R)-enantiomer (e.g. greater than 80% or greater than 90% (R)), it may be that the compound is substantially present as the (S)-enantiomer (e.g. greater than 80% or greater than 90% (S)) or it may be that said compound is a mixture of the (R) enantiomer and the (S) enantiomer, e.g. a racemic mixture.

[0047] Where the compound of formula (I) has R ¹ is H or R ³ is H, the compound may be in the form of a salt. Thus, the compound may be in the form of the alkali metal or alkali earth metal salt of said compound. The compound may be in the form of an ammonium salt of said compound. The compound may be a sodium, ammonium, potassium, calcium or magnesium salt. Typically, neither R ¹ nor R ³ are H.

[0048] Typically, the compound of formula (I) is not in the form of a salt.

[0049] Further embodiments of the invention are described in the following numbered clauses.

1. A film forming composition comprising: a polymer and at least one compound of formula (I) or a salt thereof:

wherein R ¹ and R ³ are each independently at each occurrence selected from Ci-C25-alkyl, Ci-C ₂ 5-haloalkyl, C ₂ -C ₂ 5-alkenyl, C ₂ -C25 alkynyl, (CR ⁴ R ⁴ ) _m -aryl, (CR ⁴ R ⁴ ) _m -cycloalkyl and H;

R ² is independently at each occurrence selected from: H, C(0)Ci-C25-alkyl, C(0)Ci-C ₂ 5- haloalkyl,C(0)C ₂ -C ₂₅ -alkenyl, C(0)C ₂ -C ₂ 5-alkynyl, C(0)(CR ⁴ R ⁴ ) _m -aryl, C(0)(CR ⁴ R ⁴ ) _m - cycloalkyl; C(0)(CR ⁴ =CR ⁴ )-aryl, Ci-C ₂ 5-alkyl, Ci-C ₂ 5-haloalkyl, C ₂ -C ₂₅ -alkenyl and C ₂ -C25- alkynyl;

R ⁴ is independently at each occurrence selected from: H, F, Ci-C4-alkyl and CF ₃ ;

m is an integer independently selected from: 0, 1 , 2, 3, 4 and 5;

wherein each of the aforementioned alkyl, alkenyl, alkynyl, cycloalkyi and aryl (e.g. phenyl) groups, are optionally substituted, where chemically possible, by 1 to 3 substituents which are each independently at each occurrence selected from the group consisting of: oxo, fluoro, C0 ₂ R ^a , C(0)R ^a , CONR ^a R ^a , Ci-C ₄ -alkyl, C ₂ -C ₄ -alkenyl, C ₂ -C -alkenyl, and C1-C4- haloalkyl; wherein R ^a is independently at each occurrence selected from CrC ₄ alkyl; provided that at least one of R\ R ² and R ³ is not H.

2. A composition of clause 1 , wherein R ² is H.

3. A composition of clause 1 , wherein R ² is selected from Ci-C ₂ s-haloalkyl, C ₂ -C25- alkenyl and C ₂ -C25-alkynyl.

4. A composition of clause 1 , wherein R ² is selected from C(0)Ci-C25-alkyl (e.g. C(0)Ci-Cio-alkyl and C(0)Ci-C ₈ -alkyl.

5. A composition of any one of clauses 1 to 4, wherein R ¹ is selected from Ci-Ce- alkyl, Ci-Cs-haloalkyl, C ₂ -Ce-alkenyl, C ₂ -C8 alkynyl, aryl, cycloalkyi, and heterocycloalkyi.

6. A composition of clause 5, wherein R ¹ is selected from d-Ce-alkyl, C ₂ -C8-alkenyl and C ₂ -Cs alkynyl.

7. A composition of any one of clauses 1 to 6, wherein R ³ is selected from d-Cs- alkyl, d-Cs-haloalkyl, d-Cs-alkenyl, C2-C8 alkynyl, aryl, cycloalkyi, and heterocycloalkyi.

8. A composition of clause 7, wherein R ³ is selected from d-Cs-alkyl, C ₂ -Cs-alkenyl and C2-C8 alkynyl.

9. A composition of any one of clauses 1 to 8, wherein R ¹ and R ³ are the same. 10. A composition of clause 1 , wherein the compound of formula (I) is a compound of formula (III):

wherein R ^1a is the same at each occurrence and is selected from C2-C6-alkyl.

1 1. A composition of clause 10, wherein R ^1a is C3-Cs-alkyl.

12. A composition of clause 11 , wherein R ^1a is selected from isopropyl, n-butyl or isobutyl

13. A composition of any one of clauses 1 to 12, wherein the composition is a latex.

14. A composition of clause 13, wherein the latex is a latex paint.

15. A composition of clause 13 or clause 14, wherein the latex is water based.

16. A use of a compound as described in any one of clauses 1 to 12 as a coalescent.

DETAILED DESCRIPTION

Compounds

[0050] The term C _m -C _n refers to a group with m to n carbon atoms.

[0051] The term "alkyl" refers to a linear or branched hydrocarbon chain. For example, Ci-C6-alkyl may refer to methyl, ethyl, n-propyl, / ^' so-propyl, n-butyl, /so-butyl, fe/t-butyl, n- pentyl and n-hexyl. The alkyl groups may be unsubstituted

[0052] The term "haloalkyl" refers to a hydrocarbon chain substituted with at least one halogen atom independently chosen at each occurrence from: fluorine, chlorine, bromine and iodine. The halogen atom may be present at any position on the hydrocarbon chain. For example, Ci-C6-haloalkyl may refer to chloromethyl, fluoromethyl, trifluoromethyl, chloroethyl e.g. 1 -chloromethyl and 2-chloroethyl, trichloroethyl e.g. 1 ,2,2-trichloroethyl, 2,2,2-trichloroethyl, fluoroethyl e.g. 1 -fluoromethyl and 2-fluoroethyl, trifluoroethyl e.g. 1 ,2,2-trifluoroethyl and 2,2,2-trifluoroethyl, chloropropyl, trichloropropyl, fluoropropyl, trifluoropropyl. A halo alkyl group may be a fluoroalkyl group, i.e. a hydrocarbon chain substituted with at least one fluorine atom.

[0053] The term "alkenyl" refers to a branched or linear hydrocarbon chain containing at least one double bond. The double bond(s) may be present as the E or Z isomer. The double bond may be at any possible position of the hydrocarbon chain. For example, "C ₂ - C6-alkenyl" may refer to ethenyl, propenyl, butenyl, butadienyl, pentenyl, pentadienyl, hexenyl and hexadienyl. The alkenyl groups may be unsubstituted.

[0054] The term "alkynyl" refers to a branched or linear hydrocarbon chain containing at least one triple bond. The triple bond may be at any possible position of the hydrocarbon chain. For example, "C2-C6-alkynyl" may refer to ethynyl, propynyl, butynyl, pentynyl and hexynyl. The term 'alkynyl' group encompasses groups that also contain carbon-carbon double bonds. The alkynyl groups may be unsubstituted.

[0055] The term "cycloalkyl" refers to a saturated hydrocarbon ring system containing 3, 4, 5 or 6 carbon atoms. For example, "C3-C6-cycloalkyl" may refer to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. The cycloalkyl groups may be unsubstituted.

[0056] Aryl groups have from 6 to 20 carbon atoms as appropriate to satisfy valency requirements. Aryl groups are carbocyclic groups which satisfy the Huckel rule (i.e. they contain a carbocyclic ring system containing 2(2n + 1)π electrons). Aryl groups may be optionally substituted phenyl groups, optionally substituted biphenyl groups, optionally substituted naphthalenyl groups or optionally substituted anthracenyl groups. Preferably an aryl group is an optionally substituted phenyl group. Alternatively, an aryl group is an optionally substituted naphthyl group. Preferably, an aryl group is unsubstituted.

[0057] Each of the cycloalkyl and aryl groups defined in R\ R ² , R ³ and R ⁴ may be monocyclic or may be bicyclic.

[0058] Compounds of the invention containing one or more asymmetric carbon atoms can exist as two or more stereoisomers. Where a compound of the invention contains a double bond such as a C=C or C=N group, geometric cis/trans (or Z/E) isomers are possible. Where structural isomers are inter-convertible via a low energy barrier, tautomeric isomerism ('tautomerism') can occur. This can take the form of proton tautomerism in compounds of the invention containing, for example, an imino or keto, or so-called valence tautomerism in compounds which contain an aromatic moiety. It follows that a single compound may exhibit more than one type of isomerism.

[0059] Included within the scope of the present invention are all stereoisomers, geometric isomers and tautomeric forms of the compounds of the invention, including compounds exhibiting more than one type of isomerism, and mixtures of one or more thereof.

Synthesis

[0060] The skilled chemist will appreciate that the compounds of formula (I) can be readily prepared from readily available starting materials. For example, certain compounds of formula (I) can be readily prepared from malic acid. [0061] For example, the skilled person will be immediately familiar with standard textbooks such as "Comprehensive Organic Transformations - A Guide to Functional Group Transformations", RC Larock, Wiley-VCH (1999 or later editions), "March's Advanced Organic Chemistry - Reactions, Mechanisms and Structure", M B Smith, J. March, Wiley, (5th edition or later) "Advanced Organic Chemistry, Part B, Reactions and Synthesis", FA Carey, RJ Sundberg, Kluwer Academic/Plenum Publications, (2001 or later editions), "Organic Synthesis - The Disconnection Approach", S Warren (Wiley), (1982 or later editions), "Designing Organic Syntheses" S Warren (Wiley) (1983 or later editions), "Guidebook To Organic Synthesis" RK Mackie and DM Smith (Longman) (1982 or later editions), etc., and the references therein as a guide.

[0062] The skilled chemist will exercise his judgement and skill as to the most efficient sequence of reactions for synthesis of a given target compound and will employ protecting groups as necessary. This will depend inter alia on factors such as the nature of other functional groups present in a particular substrate. Clearly, the type of chemistry involved will influence the choice of reagent that is used in the said synthetic steps, the need, and type, of protecting groups that are employed, and the sequence for accomplishing the protection/deprotection steps. These and other reaction parameters will be evident to the skilled person by reference to standard textbooks and to the examples provided herein.

[0063] Sensitive functional groups (especially hydroxyl and carboxy groups) may need to be protected and deprotected during synthesis of a compound of formulae (I). This may be achieved by conventional methods, for example as described in "Protective Groups in Organic Synthesis" by TW Greene and PGM Wuts, John Wiley & Sons Inc (1999), and references therein.

[0064] In particular, adaptation of the synthetic methods described in the examples below, could be applied in the manufacture of other compounds of the present invention.

[0065] The compounds of formula (I) can be purified by methods familiar to the skilled person. Such methods include chromatography and distillation. The compounds may be purified by fractional distillation. Alternatively, the compounds could be distilled by other techniques known in the art, e.g. wiped film evaporation, and/or distillation using a Kugelrohr apparatus or other short-path distillation technique. Certain compounds of formula (I) (e.g. compound A below) may degrade under fractional distillation techniques and it might be preferable to distil these compounds using one or more of the other purification techniques mentioned in this paragraph.

[0066] Typically, the stereochemistry of the starting malic acid will be retained in the compound of the invention. Thus, the relative proportions of the (R) and (S) enantiomers present in the compounds of formulae (I) to (VI) will often depend upon the relative proportions of the enantiomers present in the starting material. It is possible, however that some racemisation or inversion occurs during synthesis.

[0067] Cis/trans isomers may be separated by conventional techniques well known to those skilled in the art, for example, chromatography and fractional crystallisation.

[0068] Conventional techniques for the preparation/isolation of individual enantiomers when necessary include chiral synthesis from a suitable optically pure precursor or resolution of the racemate (or the racemate of a salt or derivative) using, for example, chiral high pressure liquid chromatography (HPLC).

Film-forming compositions

The film forming compositions of the invention comprise a polymer. The skilled person will be familiar with the polymers typically used in film-forming latexes such as paints. Such polymers are typically those with a high glass transition temperature. Exemplary polymers include acrylic, styrenic or acrylic-styrenic polymers and copolymers.

The inventors have found diisopropylmalate to have particularly beneficial effects when used in a composition in which the polymer is a styrene acrylic copolymer.

The inventors have found diisobutyl-2-methylglutarate to have particularly beneficial effects when used in a composition in which the polymer is an acrylic polymer.

The film forming compositions are typically aqueous.

The film forming composition may include other agents. The skilled person will be familiar with the additive components typically used in film-forming latexes such as paints and with the amounts of said components that it is appropriate to use. The film forming composition may include one or more agents selected from: surfactants, dispersants, defoamers, pigments and dye molecules, fillers, thickeners, pH modifiers (and particularly agents that increase the alkalinity of the composition), antioxidants, and biocides.

The film forming composition may include other coalescents, i.e. in addition to the compound of formula (I).

The compound of formula (I) may be combined with a commercially available resin mixture to form the film-forming compositions of the invention. Illustrative examples of such resins include those sold under the trade names Vinavil 03V, Albuvil DVV 335, Albuvil 760, Acroval 290D, Carboset CR 7700, Primal HGT6, Axilate 6493, Axilate 2435 and Axilate DS910.

A specific formulation has the following components, in addition to the compound of formula (I): Material Amount (g)

Grind Base

De-Ionized Water 140.0

Glycol Ether DPM 18.0

Tamol 165A (Pigment Dispersant) 9.5

28% Ammonium Hydroxide 1.0

Triton CF-10 (Surfactant) 1.5

Tego Foamex 1488 (Defoamer) 1.5

Kronos 2300 Ti0 ₂ 195.0

Letdown

Maincote HG-56 Acrylic Emulsion 523.0

28% Ammonium Hydroxide 4.0

De-Ionized Water 103.2

Tego Foamex 1488 (Defoamer) 2.5

15% Sodium Nitrite 9.0

Acrysol RM-8W (Thickener) 3.0

Total 963.5

Such a formulation would typically comprise from 10 to 50 g of the compound of formula (I), i.e. from about 1 % to about 5% by weight of the composition.

Properties of coalescent agents The standard industrial tests referred to below can be performed to test the properties of a coalescent within a specific latex system:

System solubility

A conventional solubility test is used to establish solubility Efficiency of Coalescense - Dry time at low temp by UN110793:1999

Minimum film forming temperature determination UNI 8490-14:1984 using a plate with a temperature gradient. Usually illustrated for a range of concentrations

- Colour development at low temperature by UNI 8941 : 1997 by evaluating

chromatic variations of coloured paints with UV spectrophotometer. Gloss can also be measured in the dry film using a standard Gloss metre at 20°, and 60° angles. This is an expression of film quality, the smoother the film in general.

Volatility (surface hardness)

Surface hardness depends on the removal of coalescent - This is determined as Koenig pendulum hardness according to UNI EN ISO 1522:2001

Open Time

This is the time taken for the paint film to phase change from liquid to solid. Using the internal method of 'GFC chimica' ML022_0:2000 as no recognised standard is available. A thin layer of a latex (e.g. paint) is applied to a glass plate and a moving needle is arranged to cut into the surface of the forming film with a moving needle. The needle can't penetrate the dry latex so measurement of the track gives the 'open time'. The longer the open time, the more easily the paint handles. Resistance to hydrolysis

Stability in pH conditions is determined by experimentation. No proscribed method is known. Certain of the market leading products hydrolyse under highly alkaline conditions to produce high odour products in situ.

Resistance to wet abrasion -UNI EN ISO 11998:2003 - prepared sample undergoes abrasion tests and loss of thickness of dried paint layer is measured. A standard abrasion pad is used for 200 brushing cycles

VOC and odour

VOC is determined according to the appropriate certification required. Exemplary national and international standards include: ISO 16000-6; Directive de I'Union Europeanne 2004/42/EC; ISO 1600 for 3 and 28 days; Green Seal GS 11 ; Eco-label; China State Environmental Protection Agency (SEPA) guidelines; and Australian Paint Approval Scheme (APAS) D181.

[0069] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0070] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0071] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

EXAMPLES

Example 1 - Preparation of di-n-butyl malate A

[0072] To a 2 litre, three necked flask the following were charged; n-butanol (1008.00 g), malic acid (651.39 g) and Xylene sulphonic acid(90%; 4.03 g) and placed under a 30 theoretical plate column fitted with a Dean & Stark apparatus. The heat was gently applied allowing the reagents to form a homogeneous solution. The water that was formed in the reaction was removed by the Dean & Stark apparatus. The reaction was continued until the base was analysed as having an acid number of 0.59 mgKOH/g. The reaction was deemed complete once no more water was collecting in the Dean & Stark. Triethylamine was added to the crude mixture in order to neutralise the Xylene Sulphonic acid and the mixture was purified by fractional distillation to provide di-n-butyl malate A (264.80 g; 86% pure by GC analysis).

Example 2 - preparation of di-isopropyl malate B

[0073] IPA (847.84 g), malic acid (650.25 g), toluene (123.39 g) and XSA (90%) (3.92 g) was charged into a 2L three necked flask and placed under a 30 theoretical plate column fitted with a Dean & Stark. The heat was gently applied allowing the reagents to form a homogeneous solution. The water that was formed in the reaction was removed by the Dean& Stark. The reaction was continued until the base was analysed as having an acid number of 3.61 mgKOH/g. The reaction was deemed complete once no more water was collecting in the Dean & Stark. Triethylamine (12.68 g) was added to the crude mixture in order to neutralise the xylene sulphonic acid and the mixture was purified by fractional distillation to provide di-isopropyl malate B (489.64 g; 98% pure by GC analysis).

Example 3 - diisobutyl malate C

Diisobutyl malate can be made analogously to diisopropylmalate and di-n-butyl malate. Example 4 - Preparation of diisobutyl-2-methyl glutarate D

[0074] The esterification process took place under a 18 theoretical plate column fitted with a Dean-Stark (D-S) apparatus. For the process, diisobutyl glutaric acid was charged (1693.14g) to a 5L flask along with a 25% excess of isobutanol (1453.75g) and 65% XSA catalyst (10.33g) for a total initial charge of 3157.22g. The first 3 fractions taken involved draining the trap of the MTBE-Water azeotrope. From that point onwards, the aqueous layer of the trap was drained until the acidity in the base dropped to 5.64 mgKOH/g when measured by autotitrator (0.1 M KOH). At this point a total of 384.86g of aqueous layer had been drained from the D-S trap. At several points in the esterification process the base was charged with additional 65% XSA catalyst, for a total of 43.66g of 65% XSA catalyst charged. The last base sample taken had an acidity of 5.639mg KOH/g in a 4.8809g sample, with a calculated 23.59g of Na ₂ CC>3 required for the washing phase. This stage was done in 20% excess, with 28.41g dissolved in 250.41g water. A second wash was then done with 201.54g water in order to remove residual solids in the vessel that had blocked the tap.

The distillation of the washed material took place under an 18 theoretical plate column initially fitted with a D-S apparatus. The material was charged (2302.63g) to a 3L flask and heated until boiling, at which point some of the isobutanol drained from the esterification process (F8) was charged back (66.54g). The next day after sampling the base the D-S apparatus was replaced with a reflux controller and a vacuum was applied for the distillation to take place at a reduced temperature. After resolving leaks in the vacuum, the desired product in a purity of 99.4% was obtained from fractions 14 - 18. The distillation was driven down to a small heel (33.75g, 1.42% of initial charge including isobutanol recharged) until the temperature in the base exceeded 200°C and boilup was lost.

Example 5 - Qualitative Testing of Coalescent Properties

[0075] The effectiveness of compounds A and B as coalescents was analysed.

Visual testing was carried out using by using a specified weight% of the coalescing agents in combination with a range of coalescent-free base paints that have differing minimum film forming temperatures (MFFTs). These were mixed on a roller for one hour to ensure adequate mixing before being allowed to stand for 30 minutes. A bead of the mixture was placed along the top of a Leneta Form 1A Penopac card and evenly distributed down the card using a K Hand Coater (manufactured by "RK PrintCoat Instruments Limited") with a wet film thickness of 40μιη. The coated films were allowed to air dry at a temperature below 18°C over a period not greater than two hours. Compound B was tested at 2.5% by weight loading in the following base paints:

• Axilat™ 6493, acrylic co-polymer, MFFT: 22°C

• Axilate™ 2435, styrene acrylic co-polymer, MFFT: 24°C

• Axilate™ DS910, aq emulsion of acrylic ester and styrene co polymer, MFFT:+16°C Compound B was also tested at 1 % by weight loading in Axilat™ 6493.

Compound A was tested at 2.5% by weight loading in loading in Axilat™ 6493. In all instances, no fracturing of the film occurred, indicating that compounds A and B are effective coalescents.

Example 6 - Quantitative Testing of Coalescent Properties

The effectiveness of compounds B, C and D as coalescents was analysed in two different base paints: Axilat™ DS910 and Axilat™ 6192. The compounds were tested against two market leading coalescents: 2,2,4-trimethyl-1 ,3-pentanediolmonoisobutyrate 1 and 2,2,4- trimethyl-1 ,3-pentanedioldiisobutyrate 2 . The coalescent were added to the base paint at concentrations of 5 wt% and 10 wt%.

The properties of the base paints when free of coalescent are as follows:

Axilat™ DS910 ^■■ styrene acrylic copolymer emulsion, 50% solid content, pH 8.0, vise. 4500mPa.s (RT), Tg 18°C, MFFT 16°C, particle size 0.1 pm, density 1.04 g/cm ³ , APEO- free aqueous; and

Axilat™ 6192 - pure acrylic copolymer emulsion, 49% solid content, pH 8.0, vise.

l OOmPa.s (RT), Tg 41 °C, MFFT 28°C, particle size 0.1 μη% density 1.08 g/cm ³ , APEO-free.

Minimum Film Forming Temperature (MFFT)

The MFFT of the paints was tested. All tests were done twice at same time (90 minutes). All mixtures were prepared 24h before the test with a minimum stirring time of 15 minutes. They were applied with a wet coating thickness of 100pm. The MFFT measurements were orientated to test method EN ISO 2115. The results are shown in Table 1.

Table 1: MFFTs for tested compositions

Concentration in Concentration in

MFFT [°C] MFFT [°C] Axilat™ DS 910 [%] Axilat™ 6192 [%]

Base only 0 16 0 28

B 5 4 5 8

B 10 3 10 3

C 5 2 5 5

C 10 3 10 1

D 5 2 5 3

D 10 2 10 0

1 5 8 5 6 1 10 5 10 1

2 5 6 5 12

2 10 4 10 0

As can be seen, all compounds tested were effective at lowering the MFFT of the base paint for both polymer systems. In particular, all three compounds A, B and C provided a lower MFFT than both comparator coalescents in the styrene/acrylate copolymer system. At 5% both compounds B and C provided a lower MFFT than both comparator coalescents in the acrylate polymer system.

Hardness

The films were tested for hardness according to the pendulum dampness test by Konig. All tests were performed twice. The films had a wet thickness of 100 μιτι. The films were allowed to dry at 21 °C and 38% humidity. The hardness was tested after 1 day, 7 days and 30 days to monitor the progression of the hardness over time. The results are shown in Tables 2 and 3.

Table 2: development of hardness over time for styrene/acrylate copolymer

Of particular note, in the styrene/acrylate copolymer system the hardness of compositions comprising compound B increased over time until after 1 month they were the hardest of the tested films.

Table 3: development of hardness over time for acrylate polymer AXILAT™ 6192 Pendulum Pendulum

Pendulum

Concentration hardness hardness hardness [units]

+ addition of... [%] [units] after 1 [units] after 7 days

day after 1 month

Base only 0 62 78 80

B 5 40 53 37

B 10 8 15 15

C 5 40 49 35

C 10 6 9 8

D 5 29 38 38

D 10 6 12 19

1 5 40 51 40

1 10 9 13 16

2 5 59 55 44

2 10 14 15 14

In the acrylate polymer system, all three compounds provided a film after 1 month that was comparable to the comparator coalescents. .

Tackiness

The films were tested for tackiness in a subjective test using by touching the film with a finger tip. The films had a wet coating thickness of 100 μπι. The films were allowed to dry for 24 h at 21 °c and 38% humidity. The results are shown in Table 4.

Table 4 - Tackiness of films after 24h

Concentration in Concentration in

Tackiness Tackiness Axilat™ DS 910 [%] Axilat™ 6192 [%]

Base only 0 not tacky 0 not tacky slightly

B 5 5 not tacky tacky

slightly

B 10 tacky 10

tacky

C slightly

5 5 not tacky tacky

C slightly

10 tacky 10

tacky

D slightly

5 5 not tacky tacky

D nearly not

10 tacky 10

tacky

1 5 not tacky 5 not tacky

1 slightly slightly

10 10

tacky tacky

2 5 slightly 5 not tacky tacky

2 10 tacky 10 not tacky

At 5 wt% coalescent, all three compounds provided films in both the acrylate polymer and styrene/acrylate copolymer systems that were comparable to comparator coalescent 2. broadly.