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1. WO2013016402 - PREPARATION OF A MULTISTAGE LATEX POLYMER

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[ EN ]

Claims:

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 Tg of the latex polymer is in the range of -20 to 50 °C.

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 °C to 15 °C.

4. The process of Claim 3 wherein 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 Tg of the latex polymer is in the range of -5 °C to 15 °C.

6. The process of Claim 5 wherein the acrylic acid monomer is a) butyl acrylate; b) ethylhexyl acrylate; or c) butyl acrylate and methyl methacrylate.

7. The process of any of Claims 1 to 6 which further includes 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.