Crosslinked polymer microparticles their preparation and use
AssigneeNippon Paint Co., Ltd.
InventorsMitsuo Yamada, Ryuzo Mizuguchi
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Abstract
Crosslinked polymer microparticles are produced by emulsion polymerizing a monomer mixture containing a crosslinking monomer having a plurality of polymerizable sites in the molecule in an aqueous medium containing a polymeric amide-acid and a neutralizing base as an emulsifier/dispersant. The polymer microparticles are incorporated to thermosetting coating compositions for rheology control and other purposes. The amide-acid moieties of the emulsifier/diapersant are capable upon curing of the coating composition of cyclizing into an imide ring and the polymer amide-acid retained on the polymer microparticles, which imide moieties do not adversely affect the properties of cured films of the coating composition.
Claims16
Crosslinked polymer microparticles having a mean particle size from about 0.01 to 10 microns produced by emulsion polymerizing ethylenically unsaturated monomers, at least 10 wt. % of which contains two or more sites of ethylenic unsaturation in the molecule, which polymer microparticles have on their surfaces a layer of a polymer amide-acid of the formula:
- ##STR6## wherein P is a hydrophobic polymeric backbone;
- R is the residue of an aliphatic, alicyclic or aromatic di- or tricarboxylic acid having two carboxyl groups attached to the same carbon atom or two adjacent carbon atoms;
- n is 1 or 2;
- and x is a positive integer.
A method for producing crosslinked polymer microparticles having a mean particle size from about 0.01 to 10 microns comprising emulsion polymerizing ethylenically unsaturated monomers, at least 10 wt. % of which contains two or more sites of ethylenic unsaturation in the molecule, in an aqueous medium containing as an emulsifier/dispersant a polymer amide-acid of the formula:
- ##STR7## wherein P is a hydrophobic polymeric backbone;
- R is the residue of an aliphatic, alicyclic or aromatic di- or tricarboxylic acid having two carboxyl groups attached to the same carbon atom or two adjacent carbon atoms;
- n is 1 or 2;
- and x is a positive integer;
- and an amount of base effective to neutralize said polymer amide-acid.
Dependencies are inferred from the claim text.