Patent ID: 6376575
Filing Date: 2002-04-23
Classification: C08G,C09D,Y10S

Abstract:
Aqueous coating composition comprising a mixture of90 to 99 wt. % of a filmforming binder composition comprising an alkali non-swellable core-shell addition polymer dispersion (I), and 1-10 wt. % of a rheology modifying addition polymer dispersion (II), the sum of the wt. % indicated for the filmforming binder composition and dispersion (II) always being 100 wt. %, wherein the polymer dispersion (I) is prepared in two or more steps by emulsion polymerization, and obtained by copolymerization in a first step of (1) 60-95 parts by weight (calculated on 100 parts by weight of the total addition polymer (I)) of a monomer mixture A consisting of (i) 65-100 mole % of a mixture of (a) 10-98 mole % of a (cyclo)alkyl (meth)acrylate of which the (cyclo)alkyl group contains 4-12 carbon atoms, (b) 0-55 mole % styrene, (c) 2-15 mole % hydroxy alkyl (meth)acrylate, and (d) 0-20 mole % of a di(cyclo)alkyl maleate and/or fumarate of which the (cyclo)alkyl groups contain 4-12 carbon atoms, the sum of the mole % indicated for monomers (a), (b), (c), and (d) always being 100 mole %, and (ii) 0-35 mole % of a copolymerizable monoethylenically unsaturated monomer other than (a), (b), (c) or (d), the sum of the mole % indicated for components (i) and (ii) always being 100 mole %, and by copolymerization in a subsequent step of(2) 5-40 parts by weight (calculated on 100 parts by weight of the total addition polymer (I)) of a monomer mixture B consisting of (e) 1-10 mole % (meth)acrylic acid, (f) 2-20 mole % hydroxy alkyl (meth)acrylate, (g) 0-55 mole % styrene, and (h) 15-97 mole % of a copolymerizable monoethylenically unsaturated monomer other than (e), (f), or (g). the sum of the mole % indicated for monomers (e), (f), (g), and (h) always being 100 mole %, with the carboxylic acid groups derived from the (meth)acrylic acid being at least partially neutralized, resulting in a non-crosslinked addition polymer I, whereby the total amount of (meth)acrylic acid in 100 parts of the total addition polymer (I) is less than 1.75 wt. %, and whereinthe polymer dispersion (II) is prepared by emulsion polymerization, and obtained by copolymerization of (iii) 99.5-99.99 parts by weight (calculated on 100 parts by weight of the total addition polymer (II)) of a monomer mixture C consisting of (j) 10-80 wt. % (cyclo)alkyl (meth)acrylate, (k) 20-50 wt. % (meth)acrylic acid, (m) 0-20 wt. % hydroxyalkyl (meth)acrylate, and (n) 0-20 wt. % of a copolymerizable monoethylenically unsaturated monomer other than (j), (k) or (m), the sum of the wt. % indicated for monomers (j), (k), (m), and (n) always being 100 wt. %, and (iv) 0.01-0.5 parts by weight (calculated on 100 parts by weight of the total addition polymer (II)) of a compound having at least two unsaturated groups, with the carboxylic acid groups derived from the (meth)acrylic acid being at least partially neutralized.