Coating compositions containing acrylic and aliphatic polyester blends

Abstract

Disclosed are solvent borne thermosetting coating compositions containing curable, aliphatic polyesters, acrylic copolymers, crosslinkers, and nonaqueous solvents. The aliphatic polyesters contain 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Blends of acrylic copolymers with these aliphatic polyesters exhibit good compatibility, viscosity reduction, and good Tg retention. Coating compositions formulated from these blends exhibit high gloss, hardness with flexibility; solvent and chemical resistance; and outdoor durability.

1 . A thermosetting coating composition, comprising:
 (A). about 2 to about 50 weight percent, based on the total weight of (A), (B), and (C) of a curable, aliphatic polyester, comprising
 i. diacid residues, comprising from about 50 to 100 mole percent of a cycloaliphatic dicarboxylic acid; 
 ii. diol residues, comprising about 50 to 100 mole percent, based on the total moles of diol residues, of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and 
 iii. about 2 to about 40 mole percent of the residues of at least one polyol, based on the total moles of diol and polyol residues; 
 wherein said curable, aliphatic polyester contains 90 or greater mole percent aliphatic diacid residues based on the total moles of diacid residues, and wherein said curable aliphatic polyester has a number average molecular weight of from about 300 to about 10,000 daltons, a hydroxyl number of about 20 to about 450 mg KOH/g of polyester, and an acid number of 0 to about 80 mg KOH/g of polyester; 
   (B). about 25 to about 88 weight percent, based on the total weight of (A), (B), and (C) of at least one acrylic copolymer of ethylenically unsaturated monomers comprising at least one hydroxyl, epoxy, carboxyl, blocked phenol, or acetoacetoxy functional group;   (C). about 10 to about 50 weight percent, based on the total weight of (A), (B), and (C), of at least one crosslinker comprising at least one compound reactive with a carboxylic acid or a hydroxyl group; and   (D). about 10 to about 60 weight percent, based on the total weight of (A), (B), (C), and (D) of at least one non-aqueous solvent.   
     
     
         2 . The coating composition according to  claim 1  wherein said diacid residues (A)(i) comprise about 50 to about 100 mole percent of the residues of at least one cycloaliphatic dicarboxylic acid chosen from 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, and about 50 to 0 mole percent of the residues at least one acylic aliphatic dicarboxylic acid chosen from dodecanedioic acid, adipic acid, sebacic acid, azelaic acid, succinic acid, succinic anhydride, and glutaric acid; and said diol residues (A)(ii) comprise about 50 to 0 mole percent of the residues of at least one diol chosen from neopentyl glycol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, heptaethylene glycol, octaethylene glycol, nonaethylene glycol, decaethylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethyl-hexane-1,3-diol, 2,2-dimethyl-1,2-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, thiodiethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl 1,3-pentanediol, p-xylenediol, hydroxypivalyl hydroxypivalate, 1,10-decanediol, and hydrogenated bisphenol A. 
     
     
         3 . The coating composition according to  claim 2  wherein said diacid residues (A)(i) comprise about 50 to about 100 mole percent of the residues of 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, or a mixture thereof, and about 0 to about 50 mole percent of the residues of adipic acid; and said diol residues (A)(ii) comprise about 50 to 0 mole percent of the residues of neopentyl glycol. 
     
     
         4 . The coating composition according to  claim 1  wherein said diacid residues comprise about 100 mole percent of the residues of hexahydrophthalic anhydride and said diol residues comprise, about 50 to about 100 mole percent of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and about 50 to 0 mole percent of the residues of neopentyl glycol. 
     
     
         5 . The coating composition according to  claim 1  wherein said curable, aliphatic polyester comprises about 3 to about 30 mole percent of the residues of at least one polyol chosen from trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerine. 
     
     
         6 . The coating composition according to  claim 1  wherein said curable, aliphatic polyester has a Tg of about −35 to about 35° C. 
     
     
         7 . The composition of  claim 1 , wherein said ethylenically unsaturated monomers of the acrylic copolymer (B) are chosen from at least one of acrylate, methacrylate, styrene, (meth)acrylic acid, and vinyl esters. 
     
     
         8 . The coating composition according to  claim 1  wherein said crosslinker (C) comprises at least one compound chosen from melamines, isocyanates, and isocyanurates. 
     
     
         9 . The coating composition according to  claim 8  wherein said crosslinker (C) comprises at least one melamine compound chosen from hexamethoxy-methylmelamine, tetramethoxymethylbenzoguanamine, tetramethoxy-methylurea, and mixed butoxy/methoxy substituted melamines. 
     
     
         10 . The coating composition according to  claim 8  wherein said crosslinker (C) comprises at least one compound chosen from toluene diisocyanate, isocyanurates of toluene diisocyanate, diphenylmethane 4,4′-diisocyanate, isocyanurates of 4,4′-diisocyanate, methylenebis-4,4′-isocyanatocyclohexane, isophorone diisocyanate, isocyanurates of isophorone diisocyanate, the biuret of 1,6-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, isocyanurates of 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, p-phenylene diisocyanate, and triphenylmethane 4,4′,4″-triisocyanate, tetramethyl xylene diisocyanate, metaxylene diisocyanate, polyisocyanates, 1,4-butylene diisocyanate, methylene bis(4-cyclohexyl isocyanate), isophorone diisocyanate and isocyanate-terminated adducts of ethylene glycol, 1,4-butylene glycol, and trimethylol propane. 
     
     
         11 . The coating composition according to  claim 1  wherein said non-aqueous solvent (D) comprises benzene, xylene, mineral spirits, naptha, toluene, acetone, methyl ethyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, n-butyl acetate, isobutyl acetate, t-butyl acetate, n-propyl acetate, isopropyl acetate, ethyl acetate, methyl acetate, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, trimethylpentanediol mono-isobutyrate, ethylene glycol mono-octyl ether, diacetone alcohol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, or combinations thereof. 
     
     
         12 . The coating composition according to  claim 1  further comprising at least one coating additive chosen from leveling agents, rheology agents, flow control agents, plasticizers, flatting agents, pigment wetting and dispersing agents, crosslinking catalysts, pigments, dyes, ultraviolet light absorbers, ultraviolet light stabilizers; defoaming agents, antifoaming agents, anti-settling agents, anti-sag agents, bodying agents, anti-skinning agents; anti-flooding agents, anti-floating agents, and corrosion inhibitors. 
     
     
         13 . A shaped object coated with the coating composition of  claim 1 . 
     
     
         14 . A thermosetting coating composition, consisting essentially of:
 (A). about 2 to about 50 weight percent, based on the total weight of (A), (B), and (C) of a curable, aliphatic polyester, consisting essentially of:
 i. diacid residues, consisting essentially of the residues of at least one aliphatic dicarboxylic acid, said aliphatic dicarboxylic acid comprising from about 50 to 100 mole percent, based on the total moles of diacid residues, of a cycloaliphatic dicarboxylic acid chosen from residues of 1,4-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, or a mixture thereof; 
 ii. diol residues, consisting essentially of about 50 to 100 mole percent, based on the total moles of diol residues, of the residues of 2,2,4,4-tetramethyl-1,3-cyclobutanediol; 
 iii. about 2 to about 40 mole percent of the residues of at least one polyol, based on the total moles of diol and polyol residues; 
 wherein said curable, aliphatic polyester has a number average molecular weight of from about 300 to about 10,000 daltons, a hydroxyl number of about 20 to about 450 mg KOH/g of polyester, and an acid number of 0 to about 80 mg KOH/g of polyester. 
   (B). about 25 to about 88 weight percent, based on the total weight of (A), (B), and (C) of at least one acrylic copolymer of ethylenically unsaturated monomers comprising at least one hydroxyl, epoxy, carboxyl, blocked phenol, or acetoacetoxy functional group;   (C). about 10 to about 50 weight percent, based on the total weight of (A), (B), and (C), of at least one crosslinker chosen from epoxides, melamines, isocyanates, and isocyanurates;   (D). about 10 to about 60 weight percent, based on the total weight of (A), (B), (C), and (D) of at least one non-aqueous solvent;   (E). a crosslinking catalyst comprising at least one compound chosen from p-toluenesulfonic acid, dodecylbenzene sulfonic acid, dinonylnaphthalene sulfonic acid, and dinonylnaphthalene disulfonic acid, benzoic acid, triphenylphosphine, dibutyltindilaurate, and dibutyltindiacetate; and   (F). at least one coating additive chosen from leveling agents, rheology agents, flow control agents, plasticizers, flatting agents, pigment wetting and dispersing agents, pigments, dyes, ultraviolet light absorbers, ultraviolet light stabilizers; defoaming agents, antifoaming agents, anti-settling agents, anti-sag agents, bodying agents, anti-skinning agents; anti-flooding agents, anti-floating agents, and corrosion inhibitors.   
     
     
         15 . The coating composition according to  claim 14  wherein said curable, aliphatic polyester has a hydroxyl number of about 30 to about 250 mg potassium hydroxide per gram of polyester, a Tg of about −35 to about 35° C., an acid number of about 2 to about 15 mg potassium hydroxide per gram of polyester, and a number average molecular weight of about 700 to about 7000 daltons. 
     
     
         16 . The composition of  claim 14 , wherein said ethylenically unsaturated monomers of the acrylic copolymer (B) are chosen from at least one of acrylate, methacrylate, styrene, (meth)acrylic acid, and vinyl esters. 
     
     
         17 . The coating composition according to  claim 14  wherein said crosslinker (C) consists essentially of at least one isocyanate chosen from isocyanurates of 4,4′-diisocyanate, methylenebis-4,4′-isocyanatocyclohexane, isophorone diisocyanate, isocyanurates of isophorone diisocyanate, 1,6-hexamethylene diisocyanate, isocyanurates of 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, polyisocyanates, 1,4-butylene diisocyanate, methylene bis(4-cyclohexyl isocyanate), isophorone diisocyanate and isocyanate-terminated adducts of ethylene glycol, 1,4-butylene glycol, and trimethylol propane. 
     
     
         18 . The coating composition according to  claim 14  wherein said nonaqueous solvent (D) consists essentially of at least one organic liquid chosen from benzene, xylene, mineral spirits, naptha, toluene, acetone, methyl ethyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, n-butyl acetate, isobutyl acetate, t-butyl acetate, n-propyl acetate, isopropyl acetate, ethyl acetate, methyl acetate, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, trimethylpentanediol mono-isobutyrate, ethylene glycol mono-octyl ether, diacetone alcohol, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.