Heat-curable resin compositions for powder paints

Claim 2

A heat-curable resin composition having a softening point of about 40° to about 150° C for powder paint which is obtained by mixing (A) a polyester having an average degree of polymerization of about 3 to about 50, a softening point of about 40° C to about 150° C, and a carboxyl group content of 250 gram equivalents/10 6 g to about 3,500 gram equivalents/10 6 g, obtained by depolymerizing a polyester comprising an aromatic dicarboxylic acid and an aliphatic dialcohol and having a high degree of polymerization represented by an intrinsic viscosity, measured in a mixed solvent of phenol and tetrachloroethane in a 1:1 weight ratio at 20° C, of about 0.4 to about 2.0, using an aromatic or saturated aliphatic polycarboxylic acid having 2 to 4 carboxyl group or an alkyl ester thereof containing 2 to 12 carboxyl groups in the molecule at a temperature of about 180° C to about 300° C, with (B) a polyepoxide compound containing about 2 to about 100 epoxide groups per molecule and having an epoxide group content of about 300 gram equivalents/10 6 g to about 9,600 gram equivalents/10 6 g and a melting point of not more than about 150° C, in amounts which satisfy the following equation: 0.5 ≦ O/C ≦ 2.0 wherein O represents the epoxide group content of the polyepoxide compound, and C represents the carboxyl group content of the polyester.

Claim 3

The heat-curable resin composition of claim 1, wherein said polyester is a polyester having an average degree of polymerization of about 5 to about 50, a softening point of about 60° C to about 120° C and a carboxyl group content of about 300 gram equivalents/10 6 g to about 2,500 gram equivalents/10 6 g.

Claim 4

The heat-curable resin composition of claim 1, wherein said compound containing about 2 to about 12 carboxyl groups per molecule is a polyvalent carboxylic acid.

Claim 5

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is terephthalic acid.

Claim 6

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is isophthalic acid.

Claim 7

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is adipic acid.

Claim 8

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is sebacic acid.

Claim 9

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is trimellitic acid.

Claim 10

The heat-curable resin composition of claim 3, wherein said polyvalent carboxylic acid is pyromellitic acid.

Claim 11

The heat-curable resin composition of claim 1, wherein said polyepoxide compound is bisphenol A diglycidyl ether type epoxy resin of the following structural formula: ##STR7## wherein n is about 0 to about 20.

Claim 12

The heat-curable resin composition of claim 1, wherein said polyepoxide compoound is a hydrogenated bisphenol A diglycidyl ether type epoxy resin of the following structural formula: ##STR8## wherein n is about 0 to about 20.

Claim 13

The heat-curable resin composition of claim 1, wherein said polyepoxide compound is a p-hydroxybenzoic acid diglycidyl ether ester type epoxy resin of the following structural formula: ##STR9## wherein n is about 0 to about 30.

Claim 14

The heat-curable resin composition of claim 1, wherein said polyepoxide compound is a triglycidyl isocyanurate type epoxy resin of the following structural formula: ##STR10## wherein R is a hydrogen atom or a methyl group.

Claim 15

The heat-curable resin composition of claim 1, wherein said polyepoxide compound is a diglycidyl hydantoin type epoxy resin of the following structural formula: ##STR11## wherein n is about 0 to about 30.

Claim 16

The heat-curable resin composition of claim 1, wherein said polyepoxide compound is an acrylic resin containing about 2 to about 100 epoxide groups per molecule.

Claim 17

The heat-curable resin composition of claim 15, wherein said acrylic resin is a copolymer having a softening point of about 40° C to about 150° C and comprising about 5 to 40 mol% of a monomer of the following general formula: ##STR12## wherein R is a hydrogen atom or a methyl group, and an ethylenically unsaturated monomer copolymerizable therewith.

Claim 18

A heat-curable resin composition for powder paints comprising: (1) 100 parts by weight of a heat-curable resin composition having a softening point of about 40° to about 150° C obtained by mixing (A) a polyester having an average degree of polymerization of about 3 to about 50, a softening point of about 40° C to about 150° C, and a carboxyl group content of about 250 gram equivalents/10 6 g to about 3,500 gram equivalents/10 6 g, obtained by depolymerizing a polyester comprising an aromatic dicarboxylic acid and an aliphatic dialcohol and having a high degree of polymerization represented by an intrinsic viscosity, measured in a mixed solvent of phenol and tetrachloroethane in a 1:1 weight ratio at 20° C, of about 0.4 to about 2.0, using an aromatic or saturated aliphatic polycarboxylic acid having 2 to 4 carboxyl groups or an alkyl ester thereof containing 2 to 12 carboxyl groups in the molecule at a temperature of about 180° C to about 300° C, with (B) a polyepoxide compound containing about 2 to about 100 epoxide groups per molecule and having an epoxide group content of about 300 gram equivalents/10 6 g to about 9,600 gram equivalents/10 6 g and a melting point of not more than about 150° C in amounts which satisfy the following equation: 0.5 ≦ O/C ≦ 2.0 wherein O represents the epoxide group content of the polyepoxide compound, and C represents the carboxyl group content of the polyester, and (2) about 0.1 to about 5 parts by weight of a salt formed between an aliphatic monocarboxylic acid containing 2 to 20 carbon atoms and an element of Group II of the Periodic Table.

Claim 19

A heat-curable resin composition for powder paints comprising: (1) 100 parts by weight of a heat-curable resin composition having a softening point of about 40° to about 150° C obtained by mixing (A) a polyester having an average degree of polymerization of about 3 to about 50, a softening point of about 40° C to about 150° C, and a carboxyl group content of about 250 gram equivalents/10 6 g to about 3,500 gram equivalents/10 6 g, obtained by depolymerizing a polyester comprising an aromatic dicarboxylic acid and an aliphatic dialcohol and having a high degree of polymerization represented by an intrinsic viscosity, measured in a mixed solvent of phenol and tetrachloroethane in a 1:1 weight ratio at 20° C, of about 0.4 to about 2.0, using an aromatic or saturated aliphatic polycarboxylic acid having 2 to 4 carboxyl groups or an alkyl ester thereof containing 2 to 12 carboxyl groups in the molecule at a temperature of about 180° C to about 300° C, with (B) a polyepoxide compound containing about 2 to about 100 epoxide groups per molecule and having an epoxide group content of about 300 gram equivalents/10 6 g to about 9,600 gram equivalents/10 6 g and a melting point of not more than about 150° C in amounts which satisfy the following equation: 0.5 ≦ O/C ≦ 2.0 wherein O represents the epoxide group content of the polyepoxide compound, and C represents the carboxyl group content of the polyester, and (2) about 0.1 to about 5 parts by weight of a salt formed between an aliphatic monocarboxylic acid containing 2 to 20 carbon atoms and an element of Group II of the Periodic Table.

Claim 20

The heat-curable resin composition of claim 17, wherein said aliphatic monocarboxylic acid is stearic acid.

Claim 21

The heat-curable resin composition of claim 17, wherein said element of Group II of the Periodic Table is magnesium.

Claim 22

The heat-curable resin composition of claim 17, wherein said element of Group II of the Periodic Table is calcium.

Claim 23

The heat-curable resin composition of claim 17, wherein said element of Group II of the Periodic Table is zinc.

Claim 24

The heat-curable resin composition of claim 17, wherein said element of Group II of the Periodic Table is barium.