Powdered thermosetting composition for coatings
AssigneeSurface Specialties, S.A.
InventorsLuc Moens, Nele Knoops, Daniel Maetens
Life of this patent
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Abstract
The present invention relates to powdered thermosetting compositions including a binder which comprises a carboxyl group containing amorphous isophthalic acid containing polyester, a carboxyl group containing semi-crystalline polyester, at least 10 parts by weight, based on the total weight of the binder, of a specific glycidyl group containing acrylic copolymer and a curing agent having functional groups reactive with the polyesters' carboxyl groups. The powdered thermosetting compositions are useful for the preparation of powdered paints and varnishes which give low gloss coatings having an outstanding flow, a remarkable weatherability and excellent mechanical properties.
Claims21
Powdered thermosetting composition including a binder which comprises
- (a) a carboxyl group containing amorphous isophthalic acid containing polyester,
- (b) a carboxyl group containing semi-crystalline polyester,
- (c) at least 10 parts by weight, based on the total weight of the binder, of a glycidyl group containing acrylic copolymer, said copolymer comprising at least 10 mole % of a glycidyl group containing monomer and having a number averaged molecular weight (Mn) of at least 10000, and
- (d) a curing agent having functional groups reactive with the polyesters' carboxyl groups.
Composition according to any of the preceding claims, wherein the carboxyl group containing semi-crystalline polyester consists of 75-100 mole % of 1,4-cyclohexanedicaroxylic acid, or terephthalic acid, or mixtures thereof, and 0-25 mole % of another diacid, based on the total of the acid constituents, and 75-100 mole % of an aliphatic non-branched diol and 0-25 mole % of another aliphatic or cycloaliphatic diol, based on the total of the alcohol constituents.
Composition according to any of claims 14, wherein the carboxyl group containing semi-crystalline polyester consists of 75-100 mole % of linear non-branched aliphatic diacid and 0-25 mole % of another diacid, based on the total of the acid constituents, and 75-100 mole % of an aliphatic non-branched or cycloaliphatic diol and 0-25 mole % of another aliphatic diol, based on the total of the alcohol constituents.
Composition according to any of the preceding claims, wherein the carboxyl group containing semi-crystalline polyester has an acid number (AN) from 10-100 mg KOH/g, a number averaged molecular weight (Mn) from 1100-17000, a fusion zone from 30-150° C., a glass transition temperature (Tg) from −50 to 50° C., a degree of crystallinity of at least 5 J/g and an ICI (cone/plate) viscosity at 175° C. from 5-20000 mPa.s.
Composition according to any of the preceding claims, wherein the glycidyl group containing acrylic copolymer consists of 10-90 mole % of a glycidyl group containing monomer selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, methyl glycidyl acrylate, methyl glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, acrylic glycidyl ether and mixtures thereof and 10-90 mole % of monomers copolymerisable with the glycidyl group containing monomers.
Composition according to any of the preceding claims, wherein the glycidyl group containing acrylic copolymer has an epoxy equivalent weight of 0.3 to 5.0 milliequivalents of epoxy/gram of polymer, a number averaged molecular weight (Mn) from 10000-25000, a glass transition temperature (Tg) from 40-85° C. and an ICI (cone/plate) viscosity at 200° C. from 50-50000 mPa.s.
Composition according to any of the preceding claims, wherein the curing agent is a polyepoxy compound or a β-hydroxyalkylamide group containing compound.
Composition according to any of the preceding claims, wherein the binder comprises, based on the total weight of the binder,
- (a) 2 to 88.5 parts by weight of the carboxyl group containing amorphous isophthalic acid containing polyester,
- (b) 1 to 85 parts by weight of the carboxyl group containing semi-crystalline polyester,
- (c) 10 to 60 parts by weight of the glycidyl group containing acrylic copolymer, and
- (d) 0.5 to 10.0 parts by weight of the curing agent having functional groups reactive with the polyesters carboxyl groups.
Composition according to any of the preceding claims, further comprising one or more additive(s) selected from the group consisting of catalysts, fillers, flow control agents, degassing agents, TV-light absorbers, light stabilizers, antioxidants and other stabilizers.
Composition according to any of the preceding claims, further comprising one or more dyes and/or pigments, such as metal oxides, metal hydroxides, metal powders, sulphides, sulphates, carbonates, silicates, carbon black, talc, china clay, barytes, iron blue, lead blue, organic reds and organic maroons.
Dependencies are inferred from the claim text.