The incorporation of adducts of glycidylesters of a, a-branche carboxylic acids and e. g. acrylic acid into the (co) polymeric network obtained by radical copoly- merization was known from e. g. R W Tess,"Epoxy Resins, Chemistry and Technology", C A May, Ed. 2nd, Marcel Dekker 1988, p. 739, R S Bauer, Chem. Tech. (1980) 692 and British Patent No. 1285520.

On the other hand it was known from e. g. P Citovicky, V Chrastova, J Sedlar, J Beniska and J Mejzlik, Angew.

Makromol. Chem. 171 (1989) 141; M Zigon, U Osredkar and A Sebenik, J. Mol. Struct., 267 (1992) 123; F B Alvey, J. Polym. Sci., Part A-1, 7 (1969), 2117, Q Xie, R Liao, D Wei and J Wang, Cuihua Xuebao, 3 (1982) 303, Chem.

Abstr. 98: 142917; S Doslop, V Vargha and F Horkay, Period. Polytech. Chem. Eng. 22 (1978) 253; H Soler, V Cadiz and A Serra, Angew. Makromol. Chem. 152 (1987) 55-60 Serra, V Cadiz, P Martinez and A Mantecon, Angew.

Makromol. Chem. 138 (1986) 185, that the 2-OH structure was the predominant compound formed when reacting a

variety of acids with the diglycidylethers and glycidylesters although mixed with the corresponding 1-OH structure in minor amounts.

Although on the one hand there is a current interest in the coating industry in faster curing coating formulations, comprising said adducts, containing primary hydroxyl groups, held responsible for a faster curing, the use of adducts having almost exclusively secondary hydroxyl groups, have been found on the other hand to be preferred in coating applications due to their lower reactivity, such as refinish coating, and preferably powder coatings wherein they increase the potlife, or in coatings, wherein a dual cure is anticipated at different temperature levels, or first finish paints wherein the shelve life is improved.

Therefor there is also a need for modified adducts of glycidylesters of a, a-branche carboxylic acids containing in the acid moiety from 5 to 15 carbon atoms and carboxylic acids and in particular ethylenically unsaturated mono-or di-carboxylic acid and more preferably acrylic acid, optionally substituted by an alkyl group, having from 1 to 4 carbon atoms, at the a-carbon atom, in which adducts only secondary OH groups or predominantly secondary OH groups occur.

With the term"predominantly"as used throughout the present specification is meant that the proportion of adducts, wherein secondary OH groups occur, in a mixture with the corresponding adducts, having primary OH groups, is at least 65 mol%, preferably at least 85 mol% and more preferably more than 90 mol%.

Therefore an object of the present invention was to provide said modified adducts of glycidylesters of a, a-branche carboxylic acids, and a carboxylic acid, and in particular optionally substituted acrylic acid, aimed at.

Another object of the present invention was to provide a process for the preparation of said adducts in a reliable and controlled way.

Still another object of the present invention was to provide curable coating compositions which have been derived from said adducts aimed at, and show improved herein before mentioned properties in particular coatings applications.

As can be derived from the copending European application No. 99203193.0 filed September 30,1999 (TS 0827 EPC), it has recently been found, that mixtures of adducts of glycidylesters of a, a-branche carboxylic acids, containing in the acid moiety from 5 to 15 carbon atoms and optionally substituted acrylic acid can be prepared, via initially formed poly (orthoester) of said carboxylic acids, in said mixture the adducts, having primary OH groups are predominant or exclusive.

Further research has surprisingly learned now, that a fast rearrangement of the initially formed adduct, having predominantly primary OH groups, is possible to form adducts having predominantly or almost exclusively secondary OH groups.

Accordingly the invention relates to a process for the preparation of adducts of glycidylesters of a, a-branche carboxylic acids having from 5 to 15 carbon atoms in the acid residue, and a carboxylic acid or its anhydride, and preferably an ethylenically unsaturated carboxylic acid, said adducts containing predominantly or exclusively secondary OH groups, comprising either the straight reaction of said glycidylester and the carboxylic acid, or the conversion of an initially formed mixture of adducts, comprising predominantly adducts bearing primary OH groups, in the presence of a catalyst selected from one or more organic phosphonium, ammonium or sulphonium compounds, or mixtures thereof, and

preferably phosphonium compounds or ammonium compounds, in the presence of an aprotonic polar organic solvent.

According to a more preferred embodiment of the process of the present invention, the adducts, bearing predominantly secondary OH groups, are straightly formed from the glycidylesters of a, a-branche acids and a carboxylic acid.

More preferred groups of catalysts to be applied in the process of the present invention are those of the formulae: wherein X is a compatible anion, and R1, R2, R3 and R4 are the same or different and represent hydrocarbon residues which may or may not be substituted by one or more functional groups, such as halogen atoms, and in the presence of an aprotonic polar organic solvent.

The compatible anion X-can be any anion used in the prior art for such catalysts but preferably it is selected from Br-, Cl-, J-, conjugate bases of weak inorganic acids, such as bicarbonate, tetrafluoroborate or biphosphate and conjugate bases of a phenol, such as a phenate or an anion derived from bisphenol A.

The more preferred anions are halides with iodide or bromide being the most preferred. The R groups borne by the phosphonium cations or ammonium cations can be aliphatic or aromatic in character. Preferably each phosphonium or ammonium cation bears at least one R group which is aromatic in character. These aromatic groups preferably are phenyl or inertly substituted phenyl.

Non-aromatic groups R are preferably C1-C20 alkyl.

More preferably all the R groups are phenyl if phosphonium catalysts of formulae I or III are used, and the R groups are more preferably C1-C20 alkyl and benzyl if ammonium catalysts of formula III are used.

Most preferably catalyst of formula III are used.

Preferred catalysts according to formula I are methylene bis (triphenylphosphonium) dibromide and derivates thereof, wherein the phenyl groups have been substituted with lower alkyl or other inert substituents.

They can be prepared by treating e. g. methylene bis (triphenylphosphonium) dibromide with Na2CO3 at about 5 wt% in water/methanol (3/1 by weight) at reflux for 3 to 4 hours, and removal the methanol by distillation.

The phosphonium halides and ammonium halides of formula III may generally be prepared by mixing in approximately equimolar proportions a phosphine or amine with a halide. The mixing may be carried out with or without the application of heat, alone or in the presence of an inert solvent such as, for example, diethylether, benzene, chloroform or carbon tetrachloride.

Preferred phosphines or amines are compounds of the formula P (R) 3 or N (R) 3 wherein at least one R is an organic radical and the other R's are hydrogen or organic radicals and preferably hydrocarbon radicals or substituted hydrocarbon radicals which may contain no more than 25 carbon atoms. Examples of the phosphines include triphenyl phosphine, tributyl phosphine, triauryl phosphine, tricyclohexyl phosphine, trihexyl phosphine, triallyl phosphine, tridodecyl phosphine, trieicosadecyl phosphine, trichlorobutyl phosphine, triethoxybutyl phosphine, trihexenyl phosphine, trixylyl phosphine, trinaphthyl phosphine, tricyclohexenyl phosphine, tri (3,4-diethyloctyl)- phosphine, trioctadecyl phosphine, dioctyldecyl phosphine, dicyclohexyl phosphine, dibutyl allyl phosphine and the like, and mixtures thereof.

Particularly preferred phosphines to be employed include the trihydrocarbyl, dihydrocarbyl and monohydrocarbyl phosphines, wherein the hydrocarbyl radicals (hydrocarbon radicals) contain from 1 to 18 carbon atoms and more particularly those wherein the hydrocarbon radicals are alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl, arylalkyl, and the like.

Preferred organic halides, to be mixed with the phosphine or amine, are those wherein the organic radical is a hydrocarbon radical, preferably having from 1 to 10 carbon atoms.

Most preferred and in particular at higher temperatures are tetralkyl ammonium halides or trialkyl benzyl ammonium halides, wherein the alkyl groups contain from 1 to 10 carbon atoms and most preferably from 1 to 6 carbon atoms, e. g. tetrabutyl ammonium-chloride, -bromide or-iodide or trimethyl benzyl ammonium chloride.

The hereinbefore specified catalysts are normally used in amounts in the range of from to 0.1-5 mol%, relative to the weight of the glycidylester, and preferably in the range of from 0.2-3 mol%.

Preferably unsaturated carboxylic acids or their anhydrides can be used for the reaction with monoglycidylester of a, a-branched carboxylic acids, the obtained adduct, having predominantly secondary OH groups, being subsequently employed as comonomer in a radical polymerization for the manufacture of binders for coating compositions.

Suitable examples of such carboxylic acids are acrylic acid, optionally substituted on the a-carbon atom by an alkyl, aryl, or cycloalkyl group having from 1-6 carbon atoms and preferably alkyl having from 1 to 3 carbon atoms, itaconic acid, maleic acid, fumaric acid, p-tert. butylbenzoic acid, p-hydroxybenzoic acid, phthalic acid, terephthalic acid, isophthalic acid, and anhydrides thereof, or mixtures thereof.

However also adducts, containing predominantly secondary OH groups, can be prepared according to the present invention, using saturated carboxylic acids or anhydrides thereof, as starting reagent.

Examples of such acids are sebacic acid, glutaric acid, adipic acid, succinic acid, VERSATIC acids, having from 5 to 15 carbon atoms, hexahydrophthalic acid, hexahydrophthalic acids substituted by an alkyl group, having from 1 to 4 carbon atoms and preferably 1 or 2 such methylhexahydrophthalic acid, ethylhexahydrophthalic acid, trimellitic acid, or hydrogenated trimellitic acid, the Diels Alder adduct of maleic anhydride with sorbic acid or the hydrogenated derivative thereof, or anhydrides thereof (VERSATIC is a trademark).

More preferred carboxylic acid reagents are acrylic acid, methacrylic acid, phthalic acid, terepthalic acid,

phthalic anhydride or maleic anhydride, and most preferred are acrylic acid or methacrylic acid.

As said hereinbefore the process of the present invention can be carried out in the presence of an aprotonic polar organic solvent such as ethers, ketones, esters or aromatics (e. g. toluene) or mixtures thereof.

Preferably the process is carried out in the presence of an ether solvent, and more preferably tert. amyl-methyl ether or tert. butyl-methyl ether, or in the presence of a ketone and more preferably of isobutyl-methyl ketone or ethyl methyl ketone.

However, the process can be carried out also without any solvent, depending on the specific type of glycidylester and on the specific type of carboxylic acid.

According to a preferred embodiment of the present invention the process is carried out at a temperature in the range of from 70-100 °C, and in the presence of polymerization inhibitor such as alkoxy phenols and in particular 4-ethoxyphenol.

It will be appreciated that another aspect of the present invention by the adducts having predominantly or exclusively secondary OH groups, and obtainable by the hereinbefore described process.

Another aspect of the present invention is formed by coating compositions, comprising at least a binder component and a liquid carrier, wherein the binder is a copolymer derived from one or more hereinbefore specified adducts as constituents, and one or more additional comonomers having ethylenic unsaturation, by copolymerization by means of a radical initiator, and a cross-linker and a curing catalyst.

The binder copolymers used for coating compositions and in particular automotive coating compositions, have usually a total OH content (% m/m) in the range of from

2.0 to 7.0, a Mw in the range of from 1500 to 20.000 and a Mw/Mn ratio in the range of from 1.4 to 5.0.

The coating compositions according to the present invention usually may contain one or more cross-linkers or curing agents.

Suitable curing agents in these coating compositions include reaction products of formaldehyde with amino resin formers such as urea, alkyleneureas, melamine and guanamines, or ethers thereof, optionally with lower alcohols having 1 to 8 carbon atoms such as methanol or butanol, and also polyisocyanates and anhydride- containing compounds, individually or in combination. The cross-linking agent is in each case added in a quantity such that the molar ratio of the OH groups of copolymer to the reactive groups of the cross-linking agent is between 0.3: 1 and 3: 1.

Formaldehyde adducts which are suitable as the curing agent are preferably those derived from urea, melamine and benzoguanamine, and also the completely or partially etherified formaldehyde-amine adducts. Particular preference is given to melamine-formaldehyde adducts, as curing agents, which are partially or completely etherified with aliphatic alcohols having 1 to 4 carbon atoms. Examples of such commercially available curing agents are MAPRENAL MF 900 and VMF 3926 (Cassella A. G.) and CYMEL 303 and 327 (Cytec) (MAPRENAL, VMF and CYMEL are trademarks). Suitable mixing proportions are in the range from 50 to 90 parts of copolymer to from 50 to 10 parts of amine-formaldehyde adduct, based on solid resin.

Suitable formaldehyde-phenol adducts and derivatives thereof may also be employed as curing agents.

In the presence of acids such as p-toluenesulphonic acid, these cross-linking agents lead to full curing of the coating. Hot curing can be carried out in a

conventional manner at temperatures of from 80 °C to 200 °C, in, for example, from 10 to 30 minutes.

Polyisocyanates are suitable for curing the products according to the invention, especially at moderate temperatures or at room temperature. Suitable poly- isocyanate components are, in principle, all aliphatic, cycloaliphatic or aromatic polyisocyanates which are known from polyurethane chemistry, alone or in mixtures.

Those which are particularly suitable are low molecular weight polyisocyanates such as, for example, hexa- methylene diisocyanate, 2,2,4- and/or 2,4,4-trimethyl- 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, tetramethyl-p-xylylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3, 3,5- trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,4'-and/or 4,4'-diisocyanato dicyclohexylmethane, 2,4'- and/or 4,4'-diisocyanatodiphenylmethane or mixtures of these isomers with their higher homologs, as are accessible in a manner known per se by phosgenization of aniline-formaldehyde condensation products, and 2,4- and/or 2,6-diisocyanatotoluene or any desired mixture of such compounds.

However, it is preferred to employ derivatives of these simply polyisocyanates, as are conventional in coatings technology. These include polyisocyanates which contain, for example biuret groups, uretdione groups, isocyanurate groups, urethane groups, carbodiimide groups or allophanate groups, as are described, for example in EP-0470461, which is hereby incorporated by reference.

The particularly preferred modified polyisocyanates include N, N', N"-tris (6-isocyanatohexyl) biuret and its mixtures with its higher homologs, as well as N, N', N"-tris (6-isocyanatohexyl) isocyanurate and its mixtures with its higher homologs containing more than one isocyanurate ring.

The cross-linking can be catalyzed by adding an organometallic compound, such as tin compounds and, if desired, tertiary amines, preferably diethylethanolamine.

Examples of appropriate tin compounds are dibutyltin dilaurate, dibutyltin diacetate and dibutyloxotin.

Compounds suitable for curing at elevated temperature, in addition, include blocked polyiso- cyanates, polycarboxylic acids and their anhydrides.

The coatings are generally cured within the temperature range of from-20 °C to 100 °C and preferably from-10 °C to 80 °C.

The invention is illustrated in more detail in the following examples, however without restricting its scope to these specific embodiments.

Example 1 An adduct of acrylic acid and CARDURA E10 glycidylester ACE (80 mol% 2-OH) was prepared by refluxing a solution of 505 mmol CARDURA E10 glycidylester, 500 mmol acrylic acid, 15 mmol EtTPPI, 50 ppm (3.5 mg) of 4-ethoxyphenol and 400 ml of tert.-amyl-methylether at 80 °C during 24 hours, giving a yield of about 85% (CARDURA is a trademark). After treatment of the cooled solution with 10 e. g. AMBERLITE ion exchanger during 45 minutes at room temperature filtration, again treatment of the solution with AMBERLITE during 1 hour at room temperature, filtration and vacuum evaporation at room temperature, the 2-OH isomer was isolated in almost quantitative yield (product II) with a content of 2-OH isomer of 80 mol% and 1-OH isomer of 20 mol% (AMBERLITE is a trademark).

Example 2 In a similar way an adduct of VERSATIC 10 acid CARDURA E10 glycidylester was prepared by refluxing a solution of 505 mmol CARDURA E10 glycidylester, 500 mmol VERSATIC 10 acid, 15 mmol EtTPPI, and 400 ml of tert.-

amyl-methylether at 80 °C during 24 hours, giving a yield of about 85%. The 2-OH adduct could be isolated in an almost quantitative yield with a content of 2-OH isomer of 80 mol% and a content of 1-OH isomer of 20 mol%.

Example 3 In a similar way, adducts of acrylic acid and CARDURA E10 glycidylester, containing from 80 mole% to 85 mole% 2-OH isomer, can be prepared by refluxing solutions of CARDURA E10 glycidylester, acrylic acid, ethyl tri (phenyl) phosphonium bromide (EtTPPBr), or ethyl tri (phenyl) phosphonium chloride (EtTPPCl), or ethyl tri (tolyl) phosphonium bromide (EtTTPBr), or ethyl tri (tolyl) phosphonium iodide (EtTTPI), or benzyl tri (phenyl) phosphonium iodide (BTPPI), or benzyl tri (phenyl) phosphonium bromide (BTPPBr), or benzyl tri (tolyl) phosphonium iodide (BTTPI).

Examples 4-15 In a similar way, adducts of acrylic acid, maleic acid methacrylic acid and phthalic acid and of monoglycidylester of a, a-branche carboxylic acid containing 10 carbon atoms in the acid moiety (CARDURA E10 esters) were prepared details of which have been listed in the following table.

In all reactions the reaction time was 20 hours after which time the conversion was 100%. Exp. No. Acid Temp. °C catalyst mol% Solvent lo OH 2o OH Acrylic Acid 80 BzTMAC 3 TAME 17, 0 83, 0 5 Acrylic Acid 80 ETPPI 5 TAME 12, 0 88, 0 6 Acrylic Acid 80 ETPPI 3 TAME 23, 0 77, 0 7 Acrylic Acid 80 ETPPI 3 none 32, 5 67, 5 8 Acrylic Acid 80 ETPPI 3 MEK 25, 0 75, 0 9 Acrylic Acid 80 ETPPI 3 toluene 37, 0 63, 0 10 Adipic Acid ss 80 ETPPI 3 TAME-- 11 Adipic Acid 110 ETPPI 3 none 33, 0 67, 0 12 Maleic Acid 80 ETPPI 3 TAME 27, 0 73, 0 13 Methacrylic Acid 80 ETPPI 3 TAME 25, 0 75, 0 14 Phthalic Acid ss 80 ETPPI 3 TAME-- 15 Phthalic Acid 110 ETPPI 3 none 27, 0 73, 0 catalysts: BzTMAC means benzyltrimethylammonium chloride<BR> ETPPI means ethyltriphenylphosphoniumjodide<BR> solvents: TAME means t-amyl methyl ether<BR> MEK means methyl ethyl keton<BR> ss: means slightly soluble

It will be appreciated from these examples that the reaction can also successfully be performed using a quaternary ammonium salt as catalyst; the reaction can be performed in other solvent types than ethers or without any solvent, and that other carboxylic acids than acrylic acid, can be applied, e. g. maleic acid, phthalic acid, methacrylic acid, VERSATIC 10 acid.