Ambient or low-temperature curable coating compositions for leather and other flexible substrates and methods of using them

Claim 2

A composition adapted to coat a flexible substrate and comprising an aqueous dispersion of: (a) an emulsion polymer containing from 1% to 60% by weight resin solids polymerized from a monomer mixture comprising (1) from 0.25% to 10% by weight of methacrolein and/or acrolein, (2) from 0.5% to 10% by weight of at least one a,a-ethylenically unsaturated carboxylic acid, and (3) up to 99.25% by weight of at least one other copolymerizable mono-ethylenically unsaturated monomer, the monomers providing a T g in the polymer of up to 0°C; and (b) a curing agent comprising (i) at least one dicarboxylic acid bis-hydrazide represented by the formula H 2 N-NH-C(O)-R-C(O)-NH-NH 2 , and/or (ii) at least one dicarboxylic acid bis-hydrazone represented by the formula R 1 R 2 C=N-NH-C(O)-R-C(O)-NH-N=CR 1 R 2 , wherein R is a polyalkylene group having from O to 34 carbon atoms or a divalent aromatic ring and R 1 and R 2 are the same or'different and are H or alkyl, the amount of bis-hydrazide or bis-hydrazone providing a ratio of hydrazide or of hydrazone groups to aldehyde groups of the polymer in the dispersion of from 1:2 to 2:1.

Claim 3

A composition as claimed in claim 1 wherein the emulsion polymer comprises a heteropolymer containing from 30% to 60% by weight resin solids, the particles of which comprise (A) from 50 to 95 parts by weight of a first polymer having a T g of up to -20°C and formed by emulsion polymerization of a first monomer mixture comprising (1) from 0.25% to 10% by weight of methacrolein and/or acrolein, (2) from 0.5% to 10% by weight of at least one α,β-ethylenically unsaturated carboxylic acid, and (3) up to 99.25% by weight of at least one other copolymerizable mono-ethylenically unsaturated monomer; and (B) from 5 to 50 parts by weight of a second polymer having a T of from -10°C to 100°C and formed by emulsion polymerization, in the presence of the first polymer, of a second monomer mixture comprising at least one copolymerizable mono-ethylenically unsaturated monomer, the sum of the parts in the first monomer mixture and'the second monomer mixture always being 100 parts by weight.

Claim 4

A composition as claimed in claim 1 or 2 wherein the other copolymerizable mono-ethylenically unsaturated monomer comprises one or more of (C I -C 24 ) alkyl methacrylate, (C 1 -C 24 ) alkyl acrylate, vinylidene halide, vinyl halide, methacrylonitrile, acrylonitrile, vinyl ester, ethylene alpha-olefin, acrylic and/or methacrylic acid ester of alcohol-ether, vinyl ether, styrene, alkyl-substituted styrene and vinyl aromatic monomer.

Claim 5

A composition as claimed in claim 2 or 3 wherein the first polymer of the heteropolymer contains units of: methacrolein, acrylic acid and/or methacrylic acid and at least one (C 1 -C 24 ) alkyl methacrylate and/or (C l -C 24 ) alkyl acrylate and the second polymer contains units of at least one (C 1 -C 8 ) alkyl methacrylate, styrene, alkyl-substituted styrene, acrylonitrile and/or methacrylonitrile.

Claim 6

A composition as claimed in claim 1 or 3 wherein the emulsion polymer contains from 30% to 60% by weight resin solids and is polymerized from a monomer mixture comprising (1) from 1% to 7.5% by weight of methacrolein (2) from 1% to 7% by weight of acrylic acid and/or methacrylic acid, and (3) up to 98% by weight of at least one (C 1 -C 24 ) alkyl methacrylate and/or at least one (C 1 -C 24 ) alkyl acrylate, the monomer providing a T g in the polymer of up to -10°C.

Claim 7

A composition as claimed in any of claims 1 to 5, where, in the formulae of the curing agent R is a polymethylene group having from O to 34 carbon atoms.

Claim 8

A flexible substrate bearing a coating comprising a composition as claimed in any of claims 1 to 6 in cured form.

Claim 9

A substrate as claimed in claim 7 which comprises leather or leather substitute.

Claim 10

A process for producing a coated flexible material comprising the steps of: 1. applying to the material at least one finish coat comprising a soft, flexible, resinous binder, optionally containing pigment, and drying the coating; 2. applying at least one plate or embossing coat and drying the coating; 3. applying at least one color coat comprising pigment and a film-forming polymer containing units of at least one acrylic and/or methacrylic acid ester and drying the coating; and 4. applying at least one top coat comprising an ambient or low-temperature curable composition comprising an aqueous dispersion of (1) an emulsion polymer having a plurality of reactive aldehyde groups and (2) a curing agent having a plurality of hydrazide groups, represented by the formula H 2 N-NH-C(0)-, or hydrazone groups, represented by the formula R 1 R 2 C=N-NH-C(O)-, wherein R 1 and R 2 are the same or different and are H or alkyl, the ratio of hydrazide groups or of hydrazone groups to aldehyde groups of the polymer in the dispersion being from 1:2 to 2:1, and drying the coating.

Claim 11

A process for producing a coated flexible material comprising the steps of: 1. applying to the material at least one finish coat comprising a soft, flexible, resinous binder, optionally containing pigment, and drying the coating; 2. applying at least one plate or embossing coat and drying the coating; 3. applying at least one color coat comprising pigment and a film-forming polymer containing units of at least one acrylic and/or methacrylic acid ester and drying the coating; and 4. applying at least one top coat comprising an ambient or low-temperature curable composition comprising an aqueous dispersion of (1) an emulsion polymer having a plurality of reactive aldehyde groups and (2) a curing agent having a plurality of hydrazide groups, represented by the formula H 2 N-NH-C(0)-, or hydrazone groups, represented by the formula R 1 R 2 C=N-NH-C(O)-, wherein R 1 and R 2 are the same or different and are H or alkyl, the ratio of hydrazide groups or of hydrazone groups to aldehyde groups of the polymer in the dispersion being from 1:2 to 2:1, and drying the coating.

Claim 12

A process as claimed in claim 9 wherein the ambient or low-temperature curable composition and optionally one or more of the finish, plate or color coats comprises a composition as claimed in any of claims 1 to 6.

Claim 13

A process as claimed in claim 9 or 10 wherein one or more of the finish, plate or embossing and color coats comprises an aqueous dispersion of an emulsion heteropolymer containing from 30% to 50% by weight resin solids, the particles of which comprise (1) from 50 to 95 parts by weight resin solids of a first polymer having a T g of up to -10°C, formed by emulsion polymerization of a first monomer mixture comprising one or more of at least one (C 1 -C 24 ) saturated or unsaturated alkyl methacrylate, at least one (C 1 -C 24 ) saturated or unsaturated alkyl acrylate, methacrylic acid, acrylic acid, styrene, at least one alkyl styrene, at least one vinyl aryl compound, at least one vinyl halide, at least one vinylidene halide, acrylonitrile, methacrylonitrile, at least one ethylenically unsaturated hydrocarbon arid β-acryloxypropionic acid, and (2) from 5 to 50 parts by weight of a second polymer having a T g of 20°C or more formed by emulsion polymerization, in the presence of the first polymer, of a second monomer comprising one or more of at least one (Cl-C4) alkyl methacrylate, at least one (C l -C 4 ) alkyl acrylate, methacrylic acid, acrylic acid, styrene, at least one alkyl styrene, at least one vinyl aryl compound, at least one vinyl halide, at least one vinylidene halide, acrylonitrile, methacrylonitrile, at least one ethylenically unsaturated hydrocarbon and β-acryloxypropionic acid, the sum of the parts in the first monomer mixture and the second monomer mixture always being 100 parts by weight.

Claim 14

A process as claimed in claim 10 wherein one or more of the finish, plate or embossing and color coats comprises a blend, in a weight ratio of from 1:10 to 10:1, of said heteropolymer dispersion and an aqueous dispersion of an emulsion polymer containing from 30% to 60% by weight resin solids comprising (A) from 50 to 95 parts by weight of a first polymer having a T g of up to -20°C formed by emulsion polymerization of a first monomer mixture comprising (i) from 0.25% to 10% by weight of methacrolein and/or acrolein, (ii) from 0.5% to 10% by weight of at least one a,a-ethylenically unsaturated carboxylic acid, and (iii) up to 99.25% by weight of at least one copolymerizable mono-ethylenically unsaturated monomer; and (B) from 5 to 50 parts by weight of a second polymer having a T g of from -10°C to 100°C formed by emulsion polymerization, in the presence of the first polymer, of a second monomer mixture comprising at least one copolymerizable mono-ethylenically unsaturated monomer, the sum of the parts in the first monomer mixture and the second monomer mixture always being 100 parts by weight.

Claim 15

A process as claimed in any of claims 9 to 12 wherein the flexible material is leather or a leather substitute.