US 6,797,387 B2 · Modified aminoplast crosslinkers and powder coating compositions containing such crosslinkers

Abstract

A crosslinking agent is provided, prepared by reacting (A) an aminoplast resin; (B) a reactive urethane group-containing adduct of a polyfunctional polymer and monoisocyanate, and (C) at least one other compound having active hydrogen groups reactive with aminoplast resin (A). Compound (C) is selected from: (i) compounds having the structure (I): wherein X is aromatic; R1, R2, and R3 each independently represents H, (cyclo)alkyl having from 1 to 12 carbon atoms, aryl, alkaryl, aralkyl, or an active hydrogen-containing group, (ii) compounds having the structure (II) or (III): where R′ and R″ each independently represents an aromatic group or an alkyl group having 1 to 12 carbon atoms; and (iii) compounds different from (i) and (ii), having a melting point of at least 80° C. Further provided are methods for preparing the crosslinking agent, curable compositions containing the crosslinking agent, and coated substrates.

Claims126

Dependent claims

A crosslinking agent comprising an ungelled reaction product of the following reactants:

(A) at least one aminoplast resin;
(B) a reactive urethane group-containing adduct which is a reaction product of the following reactants:
(1) at least one mono-isocyanate;
and
(2) at least one polyfunctional polymer having functional groups reactive with the mono-isocyanate (1);
and
(C) at least one compound different from (B) having active hydrogen groups reactive with aminoplast resin (A), said compound selected from the group consisting of at least one of:
(i) compounds having the following structure (I):
wherein X is aromatic;
R1, R2, and R3 can be the same or different and each independently represents H, (cyclo)alkyl having from 1 to 12 carbon atoms, aryl, alkaryl, aralkyl, or an active hydrogen-containing group,
provided that at least one of R1, R2, and R3 represents an active hydrogen-containing group which is reactive with the aminoplast resin (A);
(ii) compounds having the following structure (II) or (III):
where R′ and R″ are the same or different and each independently represents an aromatic group or an alkyl group having 1 to 12 carbon atoms;
and
(iii) compounds different from (i) and (ii) and having a melting point of at least 80° C., wherein said crosslinking agent is essentially free of urethane NH functionality and has a glass transition temperature of at least 25° C.

12 more elements

A method for preparing a powder crosslinking agent comprising the following steps:

(1) reacting the following reactants:
(a) at least one mono-isocyanate
(b) at least one polyfunctional polymer having functional groups reactive with the mono-isocyanate (a)
in a molar ratio of reactant (b) to reactant (a) ranging from 1:1.8 to 2.0 to form a urethane group-containing reaction product;
(2) combining the following:
(A) at least one aminoplast resin;
(B) the urethane group-containing reaction product formed in step (1);
and
(C) at least one compound different from (B) having active hydrogen groups reactive with aminoplast resin (A), said compound selected from the group consisting of at least one of:
(i) compounds having the following structure (I):
wherein X is aromatic;
R1, R2, and R3 can be the same or different and each independently represents H, (cyclo)alkyl having from 1 to 12 carbon atoms, aryl, alkaryl, aralkyl, or an active hydrogen-containing group,
provided that at least one of R1, R2, and R3 represents an active hydrogen-containing group which is reactive with the aminoplast resin (A);
(ii) compounds having the following structure (II) or (III):
where R′ and R″ are the same or different and each independently represents an aromatic group or an alkyl group having 1 to 12 carbon atoms;
and
(iii) compounds different from (i) and (ii) and having a melting point of at least 80° C.;
in a ratio of total combined moles of (B) and (C) to moles of aminoplast resin (A) ranging from 1:1.5 to 3.2 to form a reaction admixture;
and
(3) heating the reaction admixture formed in step (2) to a temperature ranging from 95° C. to 135° C. for a time sufficient to form a crosslinking agent having a glass transition temperature of at least 25° C. which is essentially free of urethane NH functionality as determined by infrared spectroscopy.

17 more elements

A curable powder coating composition comprising a solid particulate mixture of the following:

(1) a film-forming polymer having reactive functional groups,
(2) a crosslinking agent having functional groups reactive with the functional groups of (1),
said crosslinking agent comprising an ungelled reaction product of the following reactants:
(A) at least one aminoplast resin;
(B) a reactive urethane group-containing adduct which is a reaction product of the following reactants:
(1) at least one mono-isocyanate;
and
(2) at least one polyfunctional polymer having functional groups reactive with the mono-isocyanate (1);
and
(C) at least one compound different from (B) having active hydrogen groups reactive with aminoplast resin (A), said compound selected from the group consisting of at least one of:
(i) compounds having the following structure (I):
wherein X is aromatic;
R1, R2, and R3 can be the same or different and each independently represents H, (cyclo)alkyl having from 1 to 12 carbon atoms, aryl, alkaryl, aralkyl, or an active hydrogen-containing group,
provided that at least one of R1, R2, and R3 represents an active hydrogen-containing group which is reactive with the aminoplast resin (A);
(ii) compounds having the following structure (II) or (III):
where R′ and R″ are the same or different and each independently represents an aromatic group or an alkyl group having 1 to 12 carbon atoms;
and
(iii) compounds different from (i) and (ii) and having a melting point of at least 80° C.;
wherein said crosslinking agent is essentially free of urethane NH functionality and has a glass transition temperature of at least 25° C.

16 more elements

Dependencies are inferred from the claim text.

Modified aminoplast crosslinkers and powder coating compositions containing such crosslinkers

Life of this patent

Modified aminoplast crosslinkers and powder coating compositions containing such crosslinkers

Life of this patent

Abstract

Claims126