CA2216860A1 - Thermoset coating compositions having improved hardness - Google Patents

Abstract

The present invention provides for amino-crosslinkable coating formulations based on a mixture of a di- or polyhydroxy functional polymeric component selected from the group consisting of diesters, polyesters, alkyd polymers, acrylic polymers and polycarbonate polymers, a crosslinking agent such as a methylol (alkoxymethyl)amino crosslinking agent, and a reactive additive which is the ester reaction product of a phenol carboxylic acid, preferably para-hydroxybenzoic acid, and an epoxy compound selected from glycidyl ethers, glycidyl esters, linear epoxies and aromatic epoxies. The crosslinkable compositions of this invention may be used to prepare curable coating and paint formulations, and also may contain other ingredients such as a crosslinkning catalyst, fillers, pigments and the like. When cured, the coatings of this invention exhibit improved physical and chemical properties when compared with cured coatings which do not contain the ester reaction product additive.

Description

THERMOSET COATING COMPOSITIONS
HAVING IMPROVED HARDNESS
.

BACKGROUND OF THE INVENTION

Field of the Invention The present invention relates to cro.~link~ble polymer compositions, to solid crosslinked polymer compositions prepared thel t;fi olll, and to methods for hllprov..lg coating properties of films and surface coatings based thereon.

Description of Related Art Thermosettable coating formulations, particularly alkyd, acrylic, polyester or diester-based coating compositions, are often the m~tf~.ri~

2 o of choice for application to various substrates, particularly metal substrates, as a paint or a protective coating. Such coatings can be form~ ted to provide a good balance of properties such as hardness, flexibility, solvent resistance, corrosion resistance, weatherability and gloss. The enhancement of these properties depends on many factors 25 including type, molecular weight, monomer composition, and glass transition temperature (Tg) of the resin; type and amount of the crosslinker; curing conditions; curing catalysts; pigments, fillers and additives. Variations of these parameters can be used to create a wide range of differences in film properties to fit requirements for a number W O 96/33245 PCT~US96/05518 of diverse applications. However, it is not always possible to optimize all of the desirable properties eimlllt~neously.

The hardness of thermoset coating compositions can usually be s increased by either providing a resin monomer composition having high glass transition telupel~Lul~ or by increasing the crosslink density.

The achievement of increased hardness by increasing polymer Tg gives rise to polymers having increased viscosity which in turn may require the use of larger than desirable quantities of solvent to form solutions suitable for coating processes.

On the other hand, an increase in crosslink density of dior polyLy ;lluxy-co~ g polymers cont~ining a mllltifiln~tional cros.elinking agent such as a multi-alkoxy methyl amino croeelinking agent may be achieved by increasing the concentration of the hydluxy ffin~.tion~l groups present in the polymer. For example, polyester polymers made by con~l~n.~ing a dibasic acid and an excess of diol and co"l~ ;"g terminal hydroxyl groups and having a low molecular weight contain a greater number of terminal hy~oxy groups available as crosilinking sites than do the higher molecular weight m~t~ri~le Thus, an increase in hardness of such resins can be achieved eimlllt~neously with a reduction in viscosity and a reduction of the volatile solvent content of coating and paint formulations.
2s However, a very high degree of cro~linking tends to seriously reduce 3 the flexibility and may also affect other properties of the cured coating.
Also, the use of high levels of cro.celinking agents needed for a high 4 degree of cro.e~linking results in the formation of a large amount of WO 96/33245 PCI~/US96/05518 volatile by-products of the cro.~linking reaction which is undesirable in such coating formulations.

One technique for h lplovillg the hardness and other plopellies of such 5 coatings is the inclusion in the curable composition of from about 1 to 60 wt% of a bis phenolic compound, e.g., bisphenol-A, as disclosed in US-A-5166289. The polyhydric phenol component particir~tes in the cro.~linking reaction involving the base resin and the ~lnino cros.clinking agent, thereby providing cured coatings of increased o hardness.

However, the bisphenols tend to be poorly soluble in solvents norn~lly used in such compositions, and additional solvent q~l~ntities may be needed to provide the requisite solubility. The inclusion of large 15 amounts of solvent to provide more workable viscosities also increases the content of volatiles present in the composition, which is undesirable.

US-A-4331782 discloses phenol-functional polyester resins which are 2 0 vapor-curable using isocyanate cro~linkin~ agents. The phenol-functional resins are prepared by first forming an ester-alcohol adduct of a hydroxybenzoic acid and an epoxy compound, and then forming the polyester by a polyesterification reaction inclllfling the adduct, a polyol and a dibasic acid as reactants. The polyester resins are 25 =characterized as being capped by the phenol-functional adduct.

SUMMARY OF THE INVENTION

The present invention provides for cros~link~ble coating fnrm~ ti~n~
based on a llli~lUl~ of a di or polyhyLu~y functional poly(oligo)meric 5 component selected from the group cnn.ei.~ting of di(poly)esters, polyesters, alkyd polymers, acrylic polymers, polyethers, polycarbonate polymers and poly(oligo)mers which contain a co~llbil-alion of two or more of ester, ether, carbonate, acrylic and alkyd moieties in their structure; a cro~linkin3~ agent and a reactive additive which is the ester 10 reaction product of a phenol carboxylic acid; and an epoxy compound.
Preferred ester reaction products have the general formula A:

A. OH,~--\ COl R, ~
(~ O ~~Rs- OCH-C, H-R7 R4-\ OH

wherein R4 is selected from the group consisting of hydrogen, halogen, hydr~J~yl, Cl to C8 alkyl and Cl to C8 alkoxy, R5 is a direct bond or a Cl to C20 organic radical which may incorporate another phenol or 20 aliphatic hydroxyl, ester, ether and/or carbonate group in its structure, R6is hydrogen or a Cl to C20 organic radical or a direct bond which may form with R, part of a 5 or 6 carbon atom cyclic ring structure, R7 is CH2R8 wherein R8 is selected from the group con~i.cting of LydLo~y, ORg, O OCRIo and R,l wherein Rgis a plilll~y or secondary aliphatic 25 group cont~inin~ 3 to 20 carbon atoms or an aromatic group co"l~;";"g 6 to 20 carbon atoms, R is a primary, secondary or tertiary aliphatic group cont~ining 4 to 20 carbon atoms or an aromatic group co.ll~il-il~p;
6 to 20 carbon atoms, and R,l is a C2 to C20 organic radical which may forrn with R,, part of a 5 or 6 carbon atom cyclic ring structure.

More particularly, the present invention provides a cro~link~ble coating composition compri.~ing a ~ ule of:

(a.) a di- or polyhydlo~y functional oligomeric or polymeric 5 component selected from the group cnn~ ting of a polyester, a diester of a di(poly)ol and a dicarboxylic acid, an alkyd resin, a polyether, an acrylic resin and a polycarbonate resin, said polymeric component further characterized as having a number average molecular weight within the range of about 250 to about 20,000; (b.) an ester reaction o product of a phenol carboxylic acid and an epoxy functional compound;
and (c.) a methylol (alkoxymethyl) amino cros.qlinkin~ agent present in an amount effective to crosslink the composition.

The cro~link~hle compositions of this invention may be used to 15 prepare curable coating and paint form~ tion.~ having workable (sprayable) viscosities and reduced VOC content. The compositions may also contain other ingredients such as a cro~linkin~; catalyst, fillers, pigments and the like. When cured, the coatings of this invention generally exhibit hll~l~ v~d hardness properties when 20 compared with cured coatings which do not contain the epoxy-ester reaction product additive. The presence of the additive also serves to elimin~te the problem of coating softening when the coated substrate is baked for a prolonged period of time. These cured coatings also have good weatherability, good corrosion resistance and hydrolytic stability, 25 enhanced oxidative and stability, good solvent and sag re.~i~t~nce and good adhesion properties.

DETAILED DESCRIPTION OF THE lNVENTION

The present invention is based on the fact that low molecular weight reactive additives of the invention, when they are mixed with hyd~ y 5 functional polymers and the plt;rt;ll~d methylol (aLoxy methyl) ~mino curing agents, form cros~link~ble compositions in which both the hydl ~y functional polymers and the -epoxy/phenol carboxylic acid reaction product participate in the cro~ilinking reaction at baking conditions. As a result, polymer structures, incllltling highly 10 crosslinked polymer structures, can be built at baking conditions with the use of very low molecular weight raw m~t~ri~l.c and low solvent q~l~ntiti~.e.

As indicated above, the oligomeric or polymeric component of the composition of this invention may comprise a di- or polyhyd~ y functional polymer including a diester polyester, an alkyd polymer, an acrylic polymer, a polyether, a-polycarbonate polymer, or mixtures of two or more of these materials.

2 o Suitable diesters and polyesters are m~t-ori~ having the general formula I:

I. o O O O
HO-R2-O-C-R3-C-O-(:R7-O-C-R3-C-O)n-R2-OH
wherein n is 0 or an integer ranging from l to about 40, R2 is a divalent aliphatic or cycloaliphatic radical cont~ining from 2 to about 40 carbon atoms or a mixture of such radicals, and R3 is a divalent aliphatic, cycloaliphatic or aromatic radical cont~ining from 2 to about 40 carbon 3 o - atoms, or a mixture of such radicals. Obviously, when n is 0 in formula I, a simple diester is represented. When n ranges from 1 to about 40, a polyester is represented.

In the more plerelled embo~liment~ ofthe invention, R2 is the divalent 5 re~idullm of a di (poly) ol co~ g from 2 to about 20 carbon atoms, more preferably from about 2 to 10 carbon atoms, and may also contain int~rn~l ester groups.

Some plerelled examples of the diols are one or more of the following:
neopentyl glycol; ethylene glycol; hexamethylenediol; 1,2-cyclohexanedimethanol; 1,3-cyclohex~ne-limethanol; 1,4-cyclohexanedimethanol; diethylene glycol; triethylene glycol;
tetraethylene glyGol; dip-upylene glycol; poly~lu~Jylene glycol; hexylene glycol; 2-methyl-2-ethyl-1,3-propanediol; 2-ethyl-1,3 hexandediol; 1,5-pent~ner1iol; thiodiglycol; 1,3-propanediol; 1,2-propanediol; 1,2-butanediol; 1,3-butanediol; 2,3-but~ne~linl; 1,4-butanediol; 2,2,4-trimethyl-1,3-pentanediol; 1,2-cyclohexanediol; 1,3-cyclohexanediol;
1,4-cyclohexanediol; neopentyl diol hydro~y methyl isobutyrate, and mixtures thereof. Examples of polyols include triols such as glycerine, 2 o timethylol ethane, trimethylol propane, pentaerythritol and the like.

R3 in formula I above is the divalent residuum of a dicarboxylic acid having from 2 to abut 40 aliphatic carbon atoms, from about 5 to 40 cycloaliphatic carbon atoms or from 6 to about 40 aromatic carbon 25 atoms" as well as mixtures of these acids. The carboxyl groups may be present in the form of anhydride groups, lactone groups, or equivalent ester forming derivatives such as the acid halide or methyl ester. The dicarboxylic acids or derivatives are preferably one or more of the - following: phthalic anhydride, terephthalic acid, isophthalic acid, 30 naphthalene dicarboxylic acids, adipic acid, succinic acid, glutaric acid, 4~; PCT/US96/OS518 fumaric acid, maleic acid, cyclohexane dicarboxylic acid, azeleic acid, sebasic acid, dimer acid, caprolactone, propiolactone, pyromellitic dianhydride, substituted maleic and fumaric acids such as citraconic, chloromaleic, mesaconic, and substituted succinic acids such as aconitic 5 and itaconic, and mixtures thereof. Many commercially available polyesters are produced using a combination of aromatic and aliphatic dicarboxylic acids or a combination of cycloaliphatic and ~liph~tic dicarboxylic acids or combinations of all three types. However, where polyesters having low viscosity and low solvent content are desired, the o most plerelled acids used for the purposes of this invention are linear saturated or unsaturated aliphatic dicarboxylic acids having from 2 to 10 carbon atoms such as succirlic, ~;lut~ric, adipic, and sirnilar m~tf-ri~

The acrylic polymers which may be used as a polymeric component in 15 the present invention are acrylic copolymer resins. The acrylic copolymer resin is prepared from at least one hydluxy-substituted alkyl (meth) acrylate and at least one non-hydloxy-substituted alkyl (meth) acrylate. The hydroxy-substituted alkyl (meth) acrylates which can be employed as monomers comprise members selected from the group zo consisting of the following esters of acrylic or meth~-~rylic acid and aliphatic glycols: 2-hydloxye~llyl acrylate, 3-chloro-2-hydluxy~lupyl acrylate; l-hydluxy-2acryloxy propane; 2-hydlu~y~lupyl acrylate; 3-hydluxy~lupylacrylate; 2,3-dihydroxy~lu~ylacrylate; 3-hydluxybu~yl acrylate; 2-hydroxybutyl acrylate; 4-hydl uxybulyl acrylate;
2 5 diethyleneglycol acrylate; 5-hydroxypentyl acrylate; 6-hydl uxyhexyl acrylate; triethyleneglycol acrylate; 7-hydloxylleptyl acrylate; 1-hydloxy-2-methacryloxy propane; 2-hydroxypropyl methacrylate; 2,3-dihydlùxy~lo~yl methacrylate; 2-hydloxyl)ulyl methacrylate; 3-hydloxyl)lltyl methacrylate; 2-hydroxyethyl meth~ccrylate; 4-30 hydloxybLltylmethacrylate; 3,4-dihydluxybLItyl methacrylate; 5-WO 96/3324', PCT/US96105518 hydru~y~entyl methacrylate; and 7-llydru~ylleptyl 5 methacrylate. The ple;r~;lled hydroxy functional monomers for use in plepalillg the acrylic resins are hydroxy-substituted alkyl (meth) acrylates having a total of 5 to 7 carbon atoms, i.e., esters of C2 to C3 dihydric alcohols and acrylic 5 or methacrylic acids. Illustrative of 10 particularly suitable hydroxy-substituted alkyl(meth) acrylate monomers are 2-hy~;ll u~yt;lllyl methacrylate, 2-hydroxyethyl acrylate, 2-hydru~ybulyl acrylate, 2-hydluxy~lopyl methacrylate, and 2-hydlo~y~lu~yl acrylate.

10 Among the non-hydl o~y-substituted alkyl (meth)acrylate monomers which may be employed are alkyl (meth)acrylates. Preferred nonhydroxy unsaturated monomers are esters of Cl to Cl2 monohydric alcohols and acrylic or methacrylic acids, e.g., methyl methacrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, glycidyl 15 methacrylate, etc. Examples of particularly suitable monomers are butyl acrylate, butyl methacrylate and methyl methacrylate.

Additionally, the acrylic copolymer resins used in the present invention may include in their composition other monomers such as acrylic acid 2 o and methacrylic acid, monovinyl aromatic hydrocarbons cont~ining from 8 to 12 carbon atoms (including styrene, alpha-methyl styrene, vinyl toluene, t-butyl styrene, chlorostyrene and the like), vinyl chloride, vinylidene chloride, acrylonitrile, epoxy-modified acrylics and methacrylonitrile .

The acrylic copolymer preferably has a number average molecular weight not greater than 20,000, more preferably between about 500 and 6000, and most preferably between about 1000 and 5000.

CA 022l6860 l997- lO- l7 Alkyd polymers which may be used as the polymeric component of the composition of this invention have a formula similar to formula I above except that R2 is a divalent reeitl~lllm of a triol with one ~ydl o~yl group esterified with a fatty acid. Typical triols are glycerine, trimethylol 5 ethane and like m~t~ri~l~. These alkyd resins are oil modified polyester resins and are broadly the product of the reaction of a dihydric alcohol and-a dicarboxylic acid or acid derivative and an oil, fat or- carboxylic acid derived from such oil or fat which acts as a modifier. Such modifiers are typically drying oils. The polyhydric alcohol employed is 10 suitably an aliphatic alcohol, and mixtures of the alcohols may also be employed. The dicarboxylic acid, or corresponding anhydrides, may be selected from a variety of aliphatic carboxylic acids or mixtures of aliphatic and aromatic dicarboxylic acids. Suitable acids and acid ~nhydrides include, by way of example, succinic acid, adipic acid, phth~lic anhydride, isophthalic acid, trim~llitic acid (~nhydride) and bis 3 ,3 ', 4,4'-benzophenone tetracarboxylic anhydride. Mixtures of these acids and anhydrides may be employed to produce a balance of properties. As the drying oil or fatty acid there is suitably employed a saturated or unsaturated fatty acid of 12 to 22 carbon atoms or a 2 o corresponding triglyceride, that is, a corresponding f at or oil, such as those contained in animal or vegetable fats or oils. Suitable fats and oils include tall oil, castor oil, coconut oil, lard, linseed oil, palm oil, peanut oil, rapeseed oil, soybean oil and beef tallow. Such fats and oils comprise mixed triglycerides of such fatty acids as caprylic, capric, 25 lauric, myristic, palmitic, and stearic and such unsaturated fatty acids as oleic, eracic, ricinoleic, linoleic and linolenic. Chemically, these fats and oils are usually mixtures of two or more members of the class.
Alkyd resins made with saturated monocarboxylic acids and fats are preferable where improved weather resistance is of prime concern.

, Polycarbonate oligomers or polymers which may be used in pl~L)alillg the compositions of this invention are llydl uxy termin~ted polycarbonates having the general formula II:

HO-R2-O-C- [O-R2-O- (C~R3~C~O~R2~0)n~C]q~O~R2~0H
wherein q is an integer ranging from 1 to about 40, n is an integer ranging from O to 40, and R2 and R3 are as defined above. This o formula includes diesters wherein n is O q is 1 or greater which may be prepared by forming the conden.~tion product of an ~liph~tic or cycloaliphatic diol having 2 to about 40 carbon atoms with a carbonic acid bisaryl ester, such as diphenyl carbonate, followed by subsequent polyconden~tion reaction ofthis with said diol.

Also inclllded in formula II are polyester diols lengthened via carbonate linkages and cont~ining termin~l carbonate groups linking the len~hened polyester diol backbone termin~l hydloxy-c~ g end groups, in which case n in formula II is equal to or greater than 1 and q 2 0 iS greater than 1.

A third category of polycarbonate within the scope of formula II are polyester diols cont~inin~ terminal carbonate groups linking the polyester diol backbone to hydroxy-coo~ l;llg end groups, in which 25 case q in formula II is equal to 1 and n is greater than 1. These materials may be prepared by forming the cond~n.c~tion product of a polyester diol with a carbonic acid bis-aryl ester, such as diphenyl carbonate, to form the polyester-diol bis-carbonic acid ester, followed by polycondensation of this precursor with a diol to form hydroxy 3 o termin~ted diesters.

WO 96/33245 PCT/~JS96/05518 The polymeric component may also comprise poly(oligo)mers which contain a combination of two or more of ester, ether, carbonate, acrylic and alkyd moieties in their structure. Examples of such m~t~ri~l~ are poly(ether)esters, poly(ether) carbonates and poly(ether) or polyesters acrylics.

The diesters and polyesters may be prepared by well known con~l~n~tion processes using a molar excess of diol. Preferably the molar ratio of diol to dicarboxylic acid is p + l:p wherein p represents o the number of moles of dicarboxylic acid. The reaction may be conducted in the absence of or presence of an aromatic or aliphatic solvent and in the absence of or presence of a suitable polycon~l~n~tion catalyst as is known in the art.

The plt;rt;ll~d number average molecular weight (Mn) of the polymers may generally range from about 250 up to about 20,000, more preferably from about 280 up to about 10,000, and most preferably from about 300 up to about 3,000 to 6,000. Glass transition temperatures (Tg) of these materials may generally range from as low as -40~C up to +100~C or higher.

The reactive additives used in the curable compositions of this invention are m~t~ri~l.c within the general structure of formula A above.
The phenol carboxylic acid reactant used to prepare the ester reaction 25 product of formula A has the general structure:

OH ~ ~-5-COH

wherein R4 and R5 are as described above. F~mples of suitable phenol carboxylic acids include hyd~ ybenzoic acids, acids where R5 is alkylene such as phenyl acetic acid, Lydlo~y phenyl propionic acid, Lydro~yL~henyl stearic acid, and acids wherein Rs encompasses 5 additional phenol functionality such as 4,4-bis Lydlo~y~henyl pentanoic acid and the like. In a pl~rell~d embodiment of the invention, R4 in formula A is hydrogen, R5 is a direct bond, R6 is hydrogen and R7 is CH2OH, a hydrocarbon moiety or an organic moiety co"~ g ester or ether groups and c~ nt~ining from 1 to about 2 0 carbon atoms, more o preferably from about 3 to 20 carbon atoms.
.

A particular advantage with the use of the reactive additives of this invention as compared, for example, with the bisphenol-A type m~t~-ri~l~ disclosed in US-A-5166289 is that the present m~t~ri~l~ are generally more soluble in the solvents conventionally used in paint formulations and are in many cases more compatible with other ingredients present in the formulation. Thus, formulations of low viscosity which are either solvent free or contain lesser amounts of solvent can be prepared, thereby lowering the content of volatile 20 organic compounds (VOC) present in the formulation.

The plerelled reactive additives used in the curable compositions of this invention are the ester reaction products of a hydloxybenzoic acid 25 and an epoxy compound. Suitable hy(llo~ylJenzoic acids include ortho-hydroxybenzoic acid (salicylic acid), meta-hydl l~ybenzoic acid and parahydroxybenzoic acid (PHBA), with para-hydlo~ybenzoic acid ~ being most pref~l 1 ed.

The epoxy compound may be selected from the group consisting of glycidyl esters, glycidyl alcohols, glycidyl ethers, linear epoxies and aromatic epoxies. These include glycidol, glycidyl ethers of the structure:

~0 CH2-CH-CH20Rg glycidyl esters of the structure:

CH2-CH-CH2-O-C-R, ~, 15 glycidyl or oxirane compounds having the structure:

and cycloaliphatic epoxy compounds having the structures:

¢[~f~-O-RI2 ,~ O-RI2 wherein Rl2 is an organic radical having 1-12 carbon atoms which can 2 5 include ether, ester, hydl o~;yl or epoxy groups, as well as other cycloiphatic compounds having the structures:

~H7-O- ,C~-RI2 ,~CH7-O-,C-RI2 ~-O-CH2~
O~J O . 0~ 0 or~ Ja Other epoxy m~teri~l~ include epoxidized alpha-olefins and bis aromatic epoxies such as the reaction product of bisphenol A or F with epichlorohydrin.

3 5 - Suitable epoxy compounds particularly include monoepoxides cont~inin~ a terminal glycidyl group or polyepoxides contz-ining internal oxirane or glycidyl groups or terrninal glycidyl groups. Suitable epoxy compounds include glycidol, glycidyl acrylate or mPth~r.rylate monomers, alkyl glycidyl ether monomers, and low rn~ lec~ r weight copolymers of one or more of these monomers with one or more 5 ethylenically unsaturated mnnomPrs such as acrylates, mpth~crylate vinyl aromatic monomers and the like.

Other suitable epoxy compounds include the ester reaction products of epichlorohydrin with mono-or dibasic aliphatic or aromatic carboxylic 10 acids or anhydrides c~ from about 1-20 carbon atoms.
Inclusive of such acids are aliphatic acids such as acetic, butyric, isobutyric, lauric, stearic, maleic and myristic acids and aromatic acids such as benzoic, phthalic, isophthalic and terephth~lic acids as well as the corresponding ~nhydrides of such acids. Preferred such acids are 15 primary, secondary or tertiary aliphatic carboxylic acids col.l ~i..;..g from 5 to 13 carbon atoms. A prerell~;d epoxy compound ofthis type is the glycidyl ester of a mixed aliphatic, mostly tertiary, mono carboxylic acid with an average of 9 to 11 carbon atoms such as available from Exxon Chemical Co., under the trade name 2 O GLYDEXX~ or from Shell Chemical Co. under the trade name CARDURA~ E ester.

Still other epoxy compounds include glycidyl ether reaction products of epihalohydrinwith aliphatic or aromatic alcohols or polyols co..l~ g 25 from about 1 to 20 carbon atoms. Suitable alcohols include aromatic alcohols such as benzyl alcohol; aromatic polyols such as bisphenol, bisphenol A, bisphenol F, phenolphth~l~in and novolac resins; aliphatic alcohols such as ethanol, isopropanol, isobutyl alcohol, hexanol, stearyl - alcohol and the like; and aliphatic polyols such as ethylene glycol, 3 o propylene glycol and butylene glycol.

Other epoxy compounds which may be used include the monoepoxides of C8 to C20 alpha mono-olefins.

The epoxy compound may also comprise epoxidized fatty compounds.
5 Such epoxidized fatty compounds include epoxidized fatty oils, epoxidized fatty acid esters of monohydric alcohols, epoxidized fatty acid esters of polyhydric alcohols, epoxidized fatty nitrites, epoxidized fatty ~mides, epoxidized fatty amines and epoxidized fatty alcohols.
Suitable alicyclic epoxide and polyepoxide m~tPri~ include 10 dicyclopentadiene diepoxide, limonene diepoxide, and the like..
Additional useful epoxides include for example, vinyl cyclohexane dioxide, bis (3,4-epoxycyclohexyl) ~tlip~te7 3,4~
epoxycyclohexylmethyl-3,4epoxy-cycloh~x~ne carboxylate and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyel~-h~x~ne-met~ xane.
The pl ~rel 1 ed hydroxybenzoic acid/epoxy reaction product of this invention may be formed by reacting the hydlo~ybenzoic acid and the epoxy compound, optionally in a solvent therefor, at a temperature ranging from about 90~ to about 120~C to initiate such reaction. once 20 the reaction is initi~tefl, such reaction is exother_ic, and the reaction temperature can rise to a temperature of about 150~ to 175~C usually without application of external heat. The reaction temperature then is m~int~ine~l at about 150~ to 170~C (and preferably less than about 200~C) until the reaction has been determined to be substantially 2 5 complete.

Reaction products of reduced discoloration can be produced by control of the maximum temperature of the exothermic reaction. This can be achieved by a staged and/or incremental addition of one of the so reactants, e.g. the epoxy reactant, so that the reaction temperature is , WO 96/332~5 PCT/US96/05518 m~int~in~d at a temperature of about 150~C or below. The rem~inr1er of that reactant may then be added in stages or continuously while g the reaction temperature below about 150~C. This process modification gives rise to reaction products having lower Color Index 5 values A~plu~illla~ely stcichi~metric qll"ntitiçs of the epoxy compound and the phenol carboxylic acid are used in the re~ction, although a slight molar excess of epoxy may be necessary to drive the reaction to o completion.

The phenol carboxylic acid/epoxy reaction product may be blended with the base polymer at a blend ratio of f from 1 to about 60% by weight of reaction product, based on the weight of base polymer and 15 the cro.eslinking agent taken together. More pr~rell~d compositions contain the reaction product at a level of from about 2 to about 40% by weight, and most preferably at a level of from about 3 to 20% by weight, based on the weight of the base polymer and croeelinking agent taken together.
The pl~,relled methylol(alkoxymethyl) amino croeelinking agents used in the present invention are well known commercial products, and are generally made by the reaction of di(poly)amide(amine) compounds with formaldehyde and, optionally, a lower alcohol.

Examples of suitable arnino-croe.elinking resins include one or a mixture of the following materials:

CA 022l6860 l997- lO- l7 Mel~mine based-resins ,N ~
(R0CH2)2 N - C~ ,C - N (CH20R)2 ~ (CH20R)2 wherein R is the following:
o R= CH3 (Cymel~ 300, 301, 303);
R = CH3, C2H5 (Cymel~ 1116);
R = CH3. C4Hg (Cymel~' 1130, 1133) R = C4Hg (Cymel~' 1156); or R= CH3 H (Cymel~ 370,373, 380, 385) The pl~relled mel~mine is hexamethoxymethyl melamine.

Benzoll~n~mine based resins 2 o ~N~
~0CH2)2 N - C~ ~- N (CH20R)2 ~3 wherein R=CH3, C2H5 (Cymel~ 1123) Urea based resins (R0CH2)~ N-C-N (CH20R)2 wherein R= CH3, H (BeetleTM 60, BeetleTM 65) or R= C4Hg (BeetleTM 80).

CA 022 1 6860 I gg7 - I o - 17 Wo 96/33245 PCT/US96/05518 Gycoluryl based resins R0- ,CH2 ,CH20R
/ ~ H ~
O=C lC O=C
\N----N /

wherein:

R= CH3, C2H5 (Cymel~ 1171); or R= C4Hg (Cymel~' 1170).

In the present invention, the ratio of the active cros.elinking groups, e.g., methylol (alkoxymethyl) groups of the amino cro.eelinking agent to the t~rmin~l hydlo~y groups on the curable components is desirably from about 1.0: 1.0 to 15.0: 1.0, more preferably from about 1.5: 1.0 20 to 5.0: 1.0, most preferably from about 1.5: 1.0 to 4.0: 1Ø

On a weight basis, the amount of amino cro.eelinkin~ agent effective for curing the crosslink~hle binder generally ranges from about 3 to about 25 60 percent by weight, more preferably from about 10 to about 50 percent by weight based on the combined weight of the amino croeelinking agent, polymer and any other cro.e.elink~ble polymer constituent of the composition. In general, quantities of croe.elinking agent required to cure the composition are inversely proportional to the 30 number average molecular weight of the base polymer. Quantities of croselinking agent on the higher side of this range are required to properly cure polymer compositions having a relatively low number average molecular weight, e.g., from about 250 to about 3,000, whereas lesser amounts of the cros~linking agent are required to properly cure polymers having a higher number average molecular weight, e.g., from about 3,000 up to about 20,000.

5 The composition of the invention may also be cured using one or more multi-isocyanate cro~linking agents. Examples of such materials include aromatic and aliphatic di- or polyisocyantes of the type disclosed in US-A-4331782, the complete disclosure of which is incorporated herein by reference.

The quantity of cro.~linking agent required to cure the base polymer depends upon equivalent weight per hydl~yl of the base polymer. For bis-hydroxyl functional polymers (polyesters), the equivalent weight is equal to one-half the molecular weight. For polyfunctional polymers (acrylics), the equivalent weight is essentially independent of molecular weight and depends on the concentration of Lyd~ yl functional monomer in the polymer or copolymer structure.

In general, the cro~.clinking agent and the ester reaction product of 20 formula A above are present in the composition at a respective weight ratio of from about 40 to 75 parts by weight of cros~linking agent per 60 to 25 parts by weight of ester reaction product, more preferably from 50 to 70 parts by weight of the former per 50 to 30 parts by weight of the latter.
25 The present invention also provides for a novel coating composition formed by combining the oligomeric or polymer component, the phenol carboxylic acid/epoxy reaction product component, the cro.c~linking agent, and optionally a solvent. Application of the formulated coating can be made via conventional methods such as spraying, roller coating, 30 dip coating, etc., and then the coated system may be cured by baking.

WO 96/3324!i PCT/US96/05518 Suitable optional solvents which may be inrlllclecl in the curable compositions of the invention comprise toluene, xylene, ethylbenzene, tetralin, naphthalene, and solvents which are narrow cut aromatic 5 solvents comprising C~ to Cl3 aromatics such as those m~rketed by Exxon Chemical Conlpally under the name Aromatic 100, Aromatic 150, and Aromatic 200.

Other suitable solvents include acetone, methyl ethyl ketone, methyl 10 isobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, methyl heptyl ketone, isophorone, isopropanol, n-butanol, sec.-butanol, isobutanol, amyl alcohol, isoamyl alcohol, hexanols, and heptanols.

Suitable oxygenated solvents include propylene glycol monomethyl 15 ether acetate, propylene glycol propyl ether acetate, ethyl ethoxypropionate, diplopylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and like m~t~ri~ other such solvents include alkyl esters such as ethyl acetate, n-propyl acetate, butyl acetate, amyl acetate, mixtures of hexyl acetates such as sold by 2 0 Exxon Chemical Company under the name EXXATE~ 600 and mixtures of heptyl acetates sold under the name EXXATE~ 700. The list should not be considered as limiting, but rather as examples of solvents which are useful in the present invention. The type and concentration of solvents are generally selected to obtain forrnulation 25 viscosities and evaporation rates suitable for the application and baking of the coatings. Typical solvent concentrations in the formulations range from 0 to about 75% by weight with a pl~rell~d range between about 5 and 50% by weight and a most pl~fellcd range between about 10 and 40% by weight. For the preparation of high solids coatings, the amount of solvent used in the coating form~ tion is preferably less than 40% of the weight of the forml ~lAtinn.

Pigment.c are a further component which may be present in the curable 5 compositions of this invention. They are generally inelllded at a weight ratio in the range of from about 0.5 to about 5.0 to one pi ment-to-binder ratio, the term binder referring to the total weight of polymer plus cro.c.elinking agent.

10 Suitable pigm~ntc which may be included in the compositions of this invention are those opacifying pigment~ normally used in paint and coating formulations and include l;L~ .. dioxide, ~ col~iu,.l oxide, zircon, zinc oxide, iron oxides, antimony oxide, carbon black, as well as chrome yellows, greens, oranges, mixed metal oxides, ceramic pi~ment.~ and the like. Preferred pigment.~ include rutile TiO2 and particularly weather resistant coated types of TiO2. The pigments may also be blended with a suitable extender m~t~ri~l which does not contribute significantly to hiding power. Suitable PxtPnders include silica, barytes, calcium sulfate, magnesium silicate (talc), ~llllll;llllln 20 oxide, ~lllmimlm hydroxide, ~lllmimlm silicate, calcium silicate, calcium carbonate (mica), potassium ~Illmimlm silicate and other clays or clay-like m~tPri~

Satisfactory baking schedules for formulations of the present invention 25 vary widely including, but not limited to, low temperature bakes of about 20 to 30 minutes at temperatures between 90 and 105~C for large equipment applications and high temperature bakes of about 5 to 10 seconds in 300 to 375~C air for coil coating applications. In general, the substrate and coating should be baked at a sufficiently high 30 temperature for a sufficiently long time so that essentially all solvents are evaporated from the film and chemical rç~ctionq between the polymer and the crosqlinkin~ agent proceed to the desired degree of completion. The desired degree of completion also varies widely and depends on the particular combination of cured film properties required for a given application.

Acid catalysts may be used to cure systems co,~ ,g hexamethoxymethyl melamine and other amino croq.qlinking agents, and a variety of suitable acid catalysts are known to one skilled in the art o for this purpose. These include, for example, p-toluene sulfonic acid, methane sulfonic acid, nonylbenzene sulfonic acid, dinonylnapthalene disulfonic acid, dodecylbenzene sulfonic acid, phosphoric acid, phosphorous acid" phenyl acid phosphate, butyl phosphate, butyl maleatel and the like or a compatible ~ ul~ of them. These acid eat~yst3lllay be u3edintheir neat" unbloeked fGlLl OI combined -with suitable blocking agents such as amines. Typical examples of unblocked catalysts are the King Tn~lllqtries~ Inc. products with the tr~1en~me K-CIJRE~3. Examples of blocked catalysts are the King Tn~lstries, Inc. products with the tra~len~me NACURE~.

The amount of catalyst employed typically varies inversely with the severity of the baking schedule. In particular, smaller concentrations of catalysts are usually required for higher baking t~",~el~ules or longer baking times. Typical catalyst concentrations for moderate baking conditions (15 to 30 mimltes at 150~C) would be about 0.2 to 0.5 wt%
catalyst solids per polymer plus cro.qqlinking agent solids. Higher concentrations of catalyst up to about 2 wt% may be employed for cures at lower temperature or shorter times. Formulations co~ ;"i~
sufficient residual esterification catalyst, such as phosphorous acid, may =

not require the inclusion of any additional cros~linking catalyst to effect a proper cure at lower curing temperatures.

In the case of form~ tion.~ of this invention co~ g 5 h~Y~meth~ylllc~llyl m.?l~mine as the cro.~linkinP: agent and ptoluene sulfonic acid as the catalyst, prer~lle;d curing conditions at dry film thickness of about 1 mil are catalyst concentration between about 0.05 and 0.6 wt%, based on polymer solids plus cros.~linking agent solids, baking temperature between 90 and 210~C and baking time between 10 about 5 and 60 minutes. Most prt:~lled curing conditions are catalyst concentration between about 0. 05 and 0.5 wt, b~king temperature between about 120 and 180~C and baking time between about 5 and 40 mimltes.

15 As described above, the formlll~tit-ns of this invention are characterized by h~l~ved weather resistance. However, additional improvements in this and other properties can be achieved by inchltling stabilizers and stabilizing systems into the formulation. Among compounds providing improvements in weather resistance are HALS (hindered amine light 2 O stabilizers), W-screeners, and other antioxidants. Flow modifiers, rheology modifiers, pigment dispersants and the like may also be included in the composition.

Coating formulations of the present invention may be prepared by first 25 forming a mill base. The mill base may be prepared by grinding a mixture of pigment, resin and solvent in a high speed disc disperser such as Byk-Gardner DISPERMAT~ Model CV to form a pigment concentrate. This mill base is then let down (mixed) under mixing conditions with the r~m~ining components of the formulation which 3 o include additional resin, solvent, cro.~.clinkin~; agent, and the catalyst.

The coating compositions of the invention may be applied to substrates by any suitable conventional technique such as spraying, roller co~ting~
dip coating and the like. The composition may be applied in liquid form, and preferably is dispersed in an organic solvent. Typical solvent concentrations in the form~ tinn~ generally range from O to about 75%
by weight, with a pler~ d range of between about 5 and 50% by weight and a most pr~felled range of between about 10 and 40% by weight.

The crosslink density and degree of cros~linking of the composition can ~ be monitored by ev~ ting the impermeability of the cured coating to organic solvent. A suitable test for ev~ ting this property is MEK rub test as described in paragraph 5.2 of ASTM D3732. This test measures the number of double rubs of a swab soaked with methyl ethyl ketone (MEK) required to completely remove the cured coating from a substrate. Generally speaking, the coatings of this invention are crosslinked sufficiently such that MEK rub values of greater than about 5, more preferably of at least 15 and most preferably more than 50 or 100 are achieved.

Properly formlll~tecl binder paints and coatings comprising compounds of structure A above provide at least one of the improvements listed:

improved hardness-flexibility balance lower VOC at a workable viscosity improved adhesion improved anti-corrosive properties improved solvent resistance improved oxidative and/or radiation resistance improved electric resistance improved weather resistance The following examples illustrate the p~ lion of some prer~llt;d hardening agents and their use as a blend component in forming the curable polymer compositions ofthe invention. M~t~.ri~ identified in the examples by trade names are as follows:

GLYDEXXTM N- 10 - glycidal ester of a mixture of tertiary aliphatic acids having 9-11 carbon atoms available from Exxon C'hemic~l Co.
GLYDEXXTM ND-101 - Same as N-10, but less pure.
ARALDITETMDY-025 - A C8 glycidyl ether available from Ciba Geigy Corp.
CYRACURETM 6216 - A Cl6 linear epoxy available from Union Carbide.
CARGILLTM 57-5789 - A hydluxy functional polyester having a molecular weight of 900-1,000 available from McWhorter Corp.
CARGILLTM 57-5742 - A short oil tofa-based alkyd resin 2 o also available from McWhorter Corp.
RUCOFLEXTMS107-210 - Neopentyl glycol adipate diester oligomer having a molecular weight of about 560.
MIAK - Methyl isoamyl ketone SOLVENT MIX - A mixture of methyl ethyl ketone, butyl acetate, -xylene, butanol and EXXATE~'600 present at a respective weight ratio of 2:3:3:1:1.
HMMM - Hexamethoxymethyl melamine cro.~clinking agent.

BYKTM300 Silicone flow control agent from Byk-Chemie.
DC-57 - Silicone flow control agent from Dow Corning.
BYKTM 451 Arnine blocked p-toluene sulfonic acid catalyst from Byk-Chemie.
NACURETM 2500 - Blocked p-toluene sulfonic acid catalyst King Tnr~lstnes. I

10 Examples 1-4 below illustrate the preparation of four dirre~ ester reaction products of PHBA and various epoxy compounds, and the properties of each.

Example I

Synthesis of Glvcidyl Ester + PHBA

Into a 1 liter flask equipped with agitation, nitrogen, heating and temperature probe, 326.6g Glydexx~ N-10 glycidyl ester and 173.4g 20 parahydroxy benzoic (PHBA) were charged. The mixture was heated at 110~C. At that point, an exothermic reaction takes place. The maximum temperature reached was 160~C. At this point, the solution was clear. The solution was then cooled and discharged. Physical properties are given below.

Acid Number : 0 mgKOH/gram Hydroxyl Number : 301.0 mg KOHJgram NVM : >99%
Color : <3 Gardner Example 2 Synthesis of Glycidvl Ester & PHBA

5 Into a 3 liter flask equipped with heating agitation and nitrogen 326.6g Glydexx~ ND-101 and 173.4g parallydl-~xyl)enzoic acid (PE~3A) were charged. The mixture was heated to 110~C with :Igit~tion At appl~xiLualely 110~C an exothermic reaction occurred. The mixture turned from a cloudy solution to a clear solution as the temperature l0 approached a m~xil"ulll of 158~C. The solution was cooled back to room temperature. Physical characteristics are given below.

Acid Number : 2.5 mg KOH/gram Hydl oxyl Value : 417-mg KOH/grarn NVM : 98.8 Wt.%
Color : < 3 Gardner F~mple 3 Synthesis of Glvcidvl Ether + PHBA

200 g Araldite~3 DY025 and 87.6g PHBA were charged ifflo a 1 liter flask equipped with agitation, heating and nitrogen. The mixture was heated to 135~C. At 135~C an exothermic reaction occurred. The maximum temperature reached was 172~C. At about 158~C, the solution turned from cloudy to clear. The reaction was then cooled 3 c back to room temperature. Physical characteristics are given below.

TAN : 9.8 mg KOH/gram Hydroxyl Number : 360.0 mg KOH/gram NVM : 96.01 wt%

Example 4 Synthesis of Linear Epoxy + PHBA

lC 250g Cyracure'E' 6216 and 124.2g parallydl~xy-benzoic acid were charged into a 1 liter flask equipped with ~git5~tion, 35 heating and nitrogen. The reaction was heated to 150~C. At that temperature an exothermic reaction occurred and the temperature increased to 159~C.
The temperature was held at 160~C. The solution turned clear. To 15 drive the reaction to completion, the solution was m~int~in~d at 170~C
for four hours. The solution was then cooled to room temperature.
Physical properties are given below.

TAl~ : 10.5 mg KOH/gram Hydroxyl Number : 294.0 mg KOH/grarn ~VM : 97.4%

Paint formulations having compositions as set forth in the following examples were prepared by forming a mill base composition and a let down composition by the general procedure described above.

Test panels were prepared and evaluated as follows:

Thin films of the various formulations were applied to steel test panels via drawdowns. The basic procedures are outlined in ASTM Test Procedure D823-87. Test panels are either untreated Type S cold rolled steel panels obtained from the Q-Panel Col.lpally or polished 5 BonderiteT~ 1000 (ironphosphate treatment) panels obtained from Advanced Coatin~s Technolo~y Inc. Panels sizes are either 4"x 8" or 3" x 6".

Wire-wound drawdown rods and in some cases a Precision Laboratory lO Drawdown Machine (both from the Paul N. Gardner Company) are used to apply films via hand-pulled drawdowns (Method E). Target dry film thicknesses are 1 mil.

The film property evaluations conducted on all cured panels were as 15 follows:

Knoop Hardness -- ASTM D-1474 Direct Impact -- ASTM D-2794 35Reverse Impact -- ASTM D-2794 2 0 VOC -- EPA Method 24 Pencil Hardness -- ASTM D-3363 Flexibility (T-bend) -- ASTM D- 173 7 Adhesion -- ASTM D-3359 Corrosion Resistance (Salt Spray) -- ASTM B-117 MEK Rubs -- ASTM D-3732 Weathering (QUV) -- ASTM G-53 Sa~ Resistance -- ASTM D-4400 In the case of the impact tests, a 5/8 inch punch with a 0.64 inch die was employed.

F,~mple S (Control) A polyester paint was form~ ted as follows:

Millbase Amount (~) Polyester (Cargill 57-5789) 15.8 0 TiO 2 32.6 MIAK 1.6 Let Down Polyester (Cargill 57-5789) 21.7 ~MM 9.0 BYK 451 0.8 BYK 300 0.1 MIAK 15.0 20 The rcs -Iting paint had a measured volatile organic compound (VOC) content of 3.2 lb/gal. at a viscosity of 29.8 seconds (Zahn Cup #2).
The paint was baked at 177~C for 10 mimltes. One mil dry film thickness paints were drawn on Bonderite 1000 panels. The results are given below, Dry Film Testin, Pencil Hardness 2H
Knoop Hardness 17.7 Direct Impact (Ib-in) 160 T-bend (no pick) 2 T

CA 022l6860 l997- lO- l7 Adhesion 5 Corrosion R~ t~nce, Blistering (Salt Spray, 144 hrs.) 6 MEK Double Rubs 200 Gloss 600 97 Sag Resistance (mils) 1.3 Example 6 10 The formulated paint of Example 5 was modified by adding the reaction product of para-hydloxy benzoic acid (PHBA) and Glydexx@~ N-10 glycidyl ester made as described in Example 1.
Millbase Amount (~
Polyester (Cargill 57-5789) 15.8 TiO2 32.6 MIAK 1.6 Let Down Polyester (Cargill 57-5789) 14.2 2 0 ~MM 1 1 .3 Ex. 1 reactionproduct 4.1 BYK 451 0.8 BYK 300 0.1 MIAK 14.2 The paint which had a measured VOC content of 3.0 lb/gal. at a viscosity of 28.4 seconds (Zahn #2), was baked atl77~C for 10 minutes. One mil dry film thickness paints were drawn on Bonderite 1000 panels Test results are given below.

WO 96/3324~i PCT/US96/05518 Dry Film Testin Pencil Hardness 2H
Knoop Hardness 19.6 Direct Impact (lb-in) 160 T-bend (no pick) 2 T
Adhesion 5 Corrosion R~ t~nce, Blistering (Salt Spray, 144:hrs.) 10 MEK Double Rubs 200 o Gloss 60~ 98 Sag R~ t~nce (mils) >1.4 Example 7 (Control) 15 The following paint was made using a short oil Tofa alkyd.

Millbase Amount (~,) Alkyd (Cargill 57-5742) 15.0 TiO2 34.1 2 0 MIAK 1.8 Let Down Alkyd (Cargill 57-5742) 20.6 HMMM 10.7 BYK 451 0.8 BYK 300 0.1 MIAK 16.9 ~ The resulting paint had a measured VOC content of 3.1 lb/gal at a 30 viscosity of 25.0 seconds (Zahn #2). Panels were made by drawing down the paint on Bonderite 1000 panels. The panels were cured at 177~F for 10 mimltes. The physical properties of the paint are given below.
Dry Film Testin~
Pencil Hardness 2H
Knoop Hardness 16.5 Direct Impact (lb-in) 70 T-bend (no pick) 4 T
Adhesion 5 MEK Double Rubs 200 Gloss 60~ 99 Example 8 15 The alkyd form~ ti~n of control Example 7 was modified by incllltling the reaction product prepared in Example 1 in the formulation.

Millbase Amount (~) Alkyd (Cargill 57-5742) 15.0 2 O TiO2 34.1 MIAK 1.8 Let Down Alkyd (Cargill 57-5742) 13.5 HM~ 12.7 Ex. l Reaction Product 4.2 BYK 451 0.8 BYK 300 0.1 MIAK 15.8 The resulting paint had a measured VOC content of 2.9 lb/gal. at a viscosity of 25.7 seconds (Zahn #2). Painted panels were made by drawing down the paint onto Bonderite 1000 panels and baking the panels for 10 mimltes at 177~C.
5 One rnil dry film thickness paints were made. The properties of the paint are given as follows:

Dry Film Testin~ .
Pencil Hardness 2H
0 Knoop Hardness 18.4 Direct Impact (Ib-in) 80 T-bend (no pick) 4 T
Adhesion 5 MEK Double Rubs 200 Gloss 600 100 Example 9 (Control!

A low VOC paint was made using Rucoflex@3 S-107-210 polyester diol.
2 o The following formulation was used.

Amount (g) Polyester Diol (Rucoflex@3 S-107-210) 35.0 HMMM 17.5 Nacure~D 2500 0.5 Solvent Mix 6.7 Do~ Corning~ DC-57 0.1 The re.sulting paint had a measured VOC content of 1.8 lb/gal. at a viscosity of 21.7 seconds (Zahn #3). A one mil dry film thickness paint was applied on Bonderite 1000 panels. The panels were cured for 10 mimltes at 1 77~C. Results are given below:

Dry Film Testin~;
Pencil Hardness F
Direct Impact (lb-in) 120 T-bend (no pick) 4 T
Adhesion 3 MEK Double Rubs 200 Example 10 15 A paint was made by replacing 20% of the binder in Example 9 with the reaction product prepared in Example 1. The formulation used was as follows:

Amount (g) 2 0 Polyester Diol (Rucoflex~3 S-107-210) 28.0 HMMM 19.0 Ex I ReactionProduct 5.0 Nacure 2500 0.5 Solvent Mix 7.9 Dow Corning DC-57 0.1 The resultin~J paint had a measured VOG content of 1.9 lb/gal. at a viscosity of 21.9 seconds (Zahn #3). A one mill thick dry film was WO 96/3324~ PCT/US96/05518 applied to Bonderite 1000 panels. 15 The panels were cured for 10 mimlt~,c at 177~C. Test results were as follows:
Dry Film Testin~
Pencil Hardness 3H
Direct Impact (lb-in) 140 T-bend (no pick) 4 T
Adhesion 3 MEK Double Rubs 200 Example 11 The polyesterdiol formulation of Example 9 was modified by addition of the reaction product of Example 2 as follows:

Amount (~
PE Diol(Rucoflex~ S- 107-210) 28.0 Ex. 2 Reaction Product 5.05 :HMMM 19.0 Nacure 2500 0.25 DC~hl 57 0.1 Solvent Mix 7.15 The res llt~nt paint had a measured VOC content of 2.1 lb/gal. and a viscosity of 22.9 seconds (Zahn #3). One rnil dry thickness paint was 25 applied to Bonderite 1000 panels. The panels were cured for 10 minutes at 177~C. Test results are as follows:

Dry Film Testino Pencil Hardness H
Direct Impact (Ib-in) 140 WO 96/33245 PCI~/US96/05518 F~r~mple 12 The polyester diol formulation of F~mple 9 was modified by the addition of the reaction product of Example 3 as follows:
Amount (~) PE Diol(Rucoflex@~ S-107-210) 28.0 ~IMM 20.0 Ex. 3 Reaction Product 5.20 Nacure 2500 0.65 DC~'57 0.10 Solvent Mix 7.20 The r~slllting paint had a measured VOC content of 1.8 lb/gal. and a viscosity of 22.1 seconds (Zahn #3). One mil dry film thickness paint was applied to Bonderite 1000 panels. The panels were baked for 10 minutes at 177~C. Results are as follows:

Drv Film Testincr Pencil Hardness H
MEK Double Rubs 100 Example 13 The polyester diol formulation of Example 9 was modified by the 25 addition of the reaction product of Example 4, as follows:

Amount (,e;) PE Diol(Rucoflex~' S-107-210) 28.0 HMMM 19.0 3 0 Ex. 4 Reaction Product 5.20 Nacure 2500 0.65 DCO 57 0.10 Solvent Mix 7.35 5 The resulting paint had a measured VOC content of 1.9 lb/gal. and a viscosity of 24.8 seconds (Zahn #3). One mil dry film thickness paint was applied to Bonderite 1000 panels. The panels were baked for 10 es at 177~C.

Drv Film Testin~
Pencil Hardness 2H
Direct Impact (Ib-in) 100 MEK Double Rubs 200 Comparative Example 14 This example which is outside the scope of the present invention illustrates the preparation of a composition of the type described in Example 5 of US-A-Patent 5166289 wherein neopentyl glycol-bis para-hydroxybenzoic acid is used as a hardener component.

The paint formulation of Example 9 was modified by inclusion of NPG-bis PHBA in the composition, as follows:

Millbase Amount (s2;!
PE Diol(Rucoflex~ S- 107-210) 31.5 ~ HMMM 18.0 NPG-bis PHBA 4.0 3c Nacure 2500 0.32 DC~'57 0. 1 Solvent Mix 8.7 The reslllting paint had a VOC content of 2.1 lb/gal. and a viscosity of 5 24.8 seconds (Zahn #3). One mil dry film thickness paint was applied to Bonderite 1000 panels. The panels were baked for 10 mimltes at 177~C. Test results are as follows:

Pencil Hardness 2H
Direct Impact (Ib-in) 160 Analysis of the test results of the examples demonskates that formulations within the scope of this invention have hardness and impact properties comparable to those achieved in US-A-516689 and, at the same time, may be made from form~ tinns having a lower content of volatile organic compounds and workable viscosities in the range of about 20-30 Zahn seconds.

The coatin_s and paints of the invention can be used for spray, roller or 20 dip application to various metal surfaces such as automotive surfaces, building panels, metal furniture" appliances and other metal sllrf~cec and for coil coating applications, followed by suitable baking to provide hard, durable and decorative finishes.

-

Claims (14)

What is claimed is:

1. A crosslinkable coating composition comprising a mixture of:
a. a poly(oligo)meric polymer component selected from the group consisting of di (poly) esters, polyesters, alkyd resins, acrylic resins, polyether polymers, polycarbonate resins, and poly(oligo)mers which contain a combination of two or more of ester, ether, carbonate, acrylic and alkyd moieties in their structure, said polymeric component further characterized as having a number average molecular weight within the range of about 250 to 20,000; and b. an ester reaction product of a phenol carboxylic acid and an epoxy-functional compound.

2. The composition of claim 1 which further contains:(c) a crosslinking agent for said polymer component.

3. The composition of claim 2 wherein said crosslinking agent is a methylol (alkoxymethyl) amino crosslinking agent, hexamethoxymethyl melamine, or hexethoxymethyl melamine present in an amount effective to crosslink the composition or at a level of from about 3 to 60 weight percent based on the weight of crosslinking agent and crosslinkable polymer components.

4. The composition of claim 3 wherein said ester reaction product has the structure:

wherein R4 is selected from the group consisting of hydrogen, halogen, hydroxyl, C1 to C8. alkyl and C1 to C8 alkoxy, R5 is a direct bond or a C1 to C20 organic radical, R6 is hydrogen or a C1 to C2. organic radical which may form with R7 part of a 5 or 6 carbon atom cyclic ring structure, R7 is CH2R8 wherein R8 is selected from the group consisting of hydroxy, OR9, OOCR10 and R11 wherein R9 is a primary or secondary aliphatic group containing 3 to 20 carbon atoms or an aromatic group containing 6 to 20 carbon atoms, R10 is a primary, secondary or tertiary aliphatic group containing 4 to 20 carbon atoms or an aromatic group containing 6 to 20 carbon atoms, and R11 is a C2 to C20 organic radical which may form with R6 part of a 5 or 6 carbon atom cyclic ring structure; or wherein R4 and R5 are each hydrogen, R5 is a direct bond and R7 is selected from the group consisting of CH20H, a hydrocarbon moiety containing 3 to about 20 carbon atoms and an organic moiety containing ester or ether groups and containing from 3 to about 20 carbon atoms.

5. The composition of claim 4 wherein said phenol carboxylic acid is a hydroxybenzoic acid or para-hydroybenzoic acid.

6. The composition of claim 3 wherein said epoxy functional compound is a glycidyl ether or ester containing a terminal epoxy group.

7. The composition of claim 3 wherein said ester reaction product has a molecular weight in the range of from about 250 to 1000.

8. The composition of claim 3 wherein said ester reaction product is the reaction product of parahydroxybenzoic acid and a glycidyl ester of one or a mixture of aliphatic acids containing 5 to 13 carbon atoms or the glycidyl ester of an aliphatic acid containing an average of 9 to 11 carbon atoms.

9. The composition of claim 3 wherein said ester reaction product is present in said composition at a level of from about 1 to 60% or about 2 to 30% by weight based on the combined weight of said polymer and amino crosslinking agent taken together.

10. Thee composition of claim 3 wherein said polymeric component has a number average molecular weight within the range of about 250 to 10,000 or about 250 to 6,000.

11. The composition of claim 3 wherein said polymeric component is an alkyd resin or a diester or polyester polymer having the structure:

wherein n is 0 or an integer ranging from 1 to about 40, R2 is a divalent aliphatic or cycloaliphatic radical containing from 2 to about 40 carbon atoms or a mixture of such radicals, and R3 is a divalent aliphatic, cycloaliphatic or aromatic radical containing from 2 to about 40 carbon atoms, or a mixture of such radicals; or a polycarbonate polymer having the structure:

wherein q is an integer ranging from 1 to about 40, n is an integer ranging from 0 to 40, R2 is a divalent aliphatic or cycloaliphatic radical containing from 2 to about 40 carbon atoms or a mixture of such radicals and R3 is a divalent aliphatic, cycloaliphatic or aromatic radical containing from 2 to about 40 carbon atoms, or a mixture of such radicals; or the diester condensation product of neopentyl glycol and adipic acid present in a respective molar ratio of about 2 to 1; or the polyester condensation product of neopentyl glycol and adipic acid, present at a respective molar ratio of p+1 to p, wherein p is the number of moles of adipic acid.

12. A process for preparing a cured coating composition comprising:

a. applying the coating composition of claim 3 or claim 25 to a substrate;

b. drying said coating; and c. heating said coated substrate for a time and a temperature sufficient to cure said coating.

13. A cured coating composition prepared by the process of claim 12.

14. A process for preparing the crosslinkable coating composition of claim 2 comprising, forming a mixture comprising:

a. a poly(oligo)meric polymer component selected from the group consisting of di(poly)esters, polyesters, alkyd resins, acrylic resins, polyether polymers, polycarbonate resins, and poly(oligo)mers which contain a combination of two or more of ester, ether, carbonate, acrylic and alkyd moieties in their structure, said polymeric component further characterized as having a number average molecular weight within the range of about 250 to about 20,000;

b. an ester reaction product of a phenol carboxylic acid and an epoxy-functional compound; and c. a crosslinking agent for said polymer component.