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1. AU2012286950 - Preparation of a multistage latex polymer

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[ EN ]
The claims defining the invention are as follows:
1.   A process comprising the steps of:
a) contacting under emulsion polymerization conditions a first portion of an acrylic monomer with a first portion of a phosphorus acid monomer to form a first stage polymer; and
b) contacting the first stage polymer with a second portion of an acrylic monomer and a second portion of a phosphorus acid monomer under emulsion polymerization conditions to form a latex polymer;
wherein the amount of the first portion of the phosphorus acid monomer is from 2 to 8 weight percent of the weight of the first stage polymer; the weight of the second portion of the phosphorus acid monomer is from 15 to 40 weight percent of the weight of the first portion of acid monomer; the first portion of the acrylic monomer is from 5 to 50 weight percent of the first and second portions of acrylic monomer; with the proviso that the monomers are selected so that the T9 of the latex polymer is in the range of -20 to 50 0C.
2.   The process of Claim 1 wherein the first and second portions of the phosphorus acid monomers are each phosphoethyl methacrylate.
3.   The process of either of Claims 1 or 2 wherein the first and second portions of acrylic monomers each comprise methyl methacrylate and one or more monomers selected from the group consisting of ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, wherein the Tg of the latex polymer is in the range of -5 OC to 15 OC.
4.   The process of Claim 3 wherein the first and second portions of acrylic monomers each comprise methyl methacrylate and a) butyl acrylate; b) ethylhexyl acrylate; or c) butyl acrylate and ethyl acrylate; wherein the amount of the first phosphorus acid monomer is from 2 to 4 weight percent of the weight of the first stage polymer; and the first acrylic monomer is from 20 to 40 weight percent of the first and second acrylic monomers.
5.   The process of either of Claims 1 or 2 wherein, in either or both of steps a) and b), styrene is contacted with the acrylic and phosphorus acid monomers under polymerization conditions; and wherein the acrylic monomer is one or more monomers selected from the group consisting of methyl methacrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; wherein the T9 of the latex polymer is in the range of -5 OC to 15 OC.
6.   The process of Claim 5 wherein the acrylic monomer is a) butyl acrylate; b) 2-ethylhexyl acrylate; or c) butyl acrylate and methyl methacrylate.
7.   The process of any one of Claims 1 to 6 which further comprises the step of contacting the latex with inorganic pigment particles under shear to form a latex pigment composite.
8.   A coatings formulation comprising the latex pigment composite of Claim 7, a binder, and a thickener.
9.   A  latex  polymer  formed   by  the  process  according   to  any  one  of claims  1  to 7.