Aqueous cross-linking compositions and methods

A water-borne polymeric composition, which consists essentially of

• water;
• one or more polymers formulated from one or more monomers of which at least one is a monomer that yields acetaldehyde as a hydrolysis product, said one or more polymers being for coalescence or drying into polymer solids, each polymer comprising one or more carbonyl groups, one or more epoxy groups, or both one or more carbonyl groups and one or more epoxy groups;
• and
• a cross-linking agent, as well as a blocked cross-linking agent having at least one hydrazone group incorporated therein, along with an amount of a ketone or aldehyde, the blocked cross-linking agent being the reaction product of the ketone or aldehyde with the cross-linking agent, the composition being such that in its equilibrium state as formulated the cross-linking agent constitutes 3% or less of the aggregate cross-linking and blocked cross-linking functional groups, and further such that a reduction of the amount of ketone or aldehyde causes the equilibrium to be shifted substantially toward the cross-linking agent's production,
• wherein the blocked cross-linking agent has the following formula:
• wherein R is a divalent organic group or a covalent bond and each of R′ and R″ is selected to be independently of the other a cyclic organic group.

A method of making a cross-linked polymeric material, which consists essentially of combining into a composition

• an aqueous dispersion of a first polymer moiety and a second polymer moiety, said moieties being of the same or different polymers, each said moiety having incorporated therein one or more carbonyl groups, one or more epoxy groups, or both one or more carbonyl groups and one or more epoxy groups, at least one of said polymer moieties being formulated from one or more monomers of which at least one is a monomer that yields acetaldehyde as a hydrolysis product;
• and
• a cross-linking agent, as well as a blocked cross-linking agent having at last one hydrazone group incorporated therein, along with an amount of a ketone or aldehyde, the blocked cross-linking agent being the reaction product of the ketone or aldehyde with the cross-linking agent, the composition being such that in its equilibrium state as formulated the cross-linking agent constitutes 3% or less of the aggregate cross-linking and blocked cross-linking functional groups;
• and
• bringing about a reduction of the amount of ketone or aldehyde which causes the equilibrium to be shifted substantially toward the cross-linking agent's production.

A water-borne primer latex, comprising:

• water;
• one or more polymers having a number average molecular weight less than 100,000 Daltons, and a glass transition temperature less than 10° C., each of said polymers being formulated from one or more monomers of which at least one is a monomer that yields acetaldehyde as a hydrolysis product, and having one or more carbonyl groups, one or more epoxy groups, or a combination of one or more carbonyl groups and one or more epoxy groups;
• and
• a blocked cross-linking agent having at least one hydrazone group incorporated therein.