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US 12,715,999 B2Granted
Aqueous dispersion of opacifying pigment particles
AssigneeRohm and Haas Company
InventorsQing Zhang, Andrew J. Swartz, Michael W. Leonard
Life of this patent
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Abstract
The present invention relates to a waterborne composition comprising an aqueous dispersion of first and second multistage polymer particles, wherein each of the first and second polymer particles comprises a water-occluded core and a high Tg polymeric shell wherein the second multistage polymer particles further comprise a polymeric binder layer superposing the shell. The composition of the present invention is useful for reducing the load of TiO2 in paint formulations, while producing coatings with excellent hiding and scrub resistance.
Claims12
A waterborne composition comprising an aqueous dispersion of first and second multistage polymer particles, wherein each of the first and second multistage polymer particles comprises:
- a) a water-occluded core comprising from 30 to 50 weight percent structural units of a salt of methacrylic acid and from 50 to 70 weight percent structural units of a nonionic monoethylenically unsaturated monomer, based on the weight of structural units of monomers in the water-occluded core, wherein the nonionic monoethylenically unsaturated monomer is one or more acrylates or methacrylates selected from the group consisting of as methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate 2-ethylhexyl acrylate, methyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, lauryl methacrylate, and cyclohexyl methacrylate;
- and a monoethylenically unsaturated aromatic compound selected from the group consisting of styrene, α-methylstyrene, and 4-t-butylstyrene;
- and
- b) a polymeric shell having a Tg in the range of from 90° C. to 115° C., wherein the polymeric shell comprises from 89 to 93 weight percent structural units of styrene, from 4 to 5 weight percent structural units of methyl methacrylate, from 0.9 to 2 weight percent structural units of cyclohexyl methacrylate, from 2 to 3 weight percent structural units of methacrylic acid, and from 0.1 to 0.5 weight percent structural units of allyl methacrylate;
- wherein the second multistage polymer particles further comprise:
- c) a layer of a film forming polymeric binder superposing the polymeric shell, which film forming polymeric binder has a Tg in the range of from −20° C. to 15° C. and comprises structural units of at least one monoethylenically unsaturated monomer, wherein the film forming polymeric binder is an acrylic or styrene acrylic binder;
- wherein the weight-to-weight ratio of structural units of monomers in the water-occluded core to the polymeric shell in the first and second multistage polymer particles is in the range of 1:10 to 1:20;
- the weight-to-weight ratio of the film forming polymeric binder to the sum of the polymeric shell and the structural units of monomers in the water-occluded core in the second multistage polymer particles is in the range of from 1:1 to 3.5:1;
- the weight-to-weight ratio of the first multistage polymer particles to the second multistage polymer particles is in the range of from 0.15:1 to 1.0:1;
- the z-average particle size of the first multistage polymer particles is in the range of from 200 nm to 2000 nm;
- and
- the z-average particle size of the second multistage polymer particles is in the range of from 300 nm to 750 nm;
- and
- wherein the first multistage polymer particles do not have a layer of a film forming polymeric binder superposing the polymeric shell.
11 more elements
A waterborne composition comprising an aqueous dispersion of first and second multistage polymer particles, wherein:
- the first multistage polymer particles consist of:
- a) a water-occluded core comprising from 30 to 50 weight percent structural units of a salt of methacrylic acid and from 50 to 70 weight percent structural units of a nonionic monoethylenically unsaturated monomer, based on the weight of structural units of monomers in the water-occluded core;
- and b) a polymeric shell having a Tg in the range of from 90° C. to 115° C.;
- and
- wherein the second multistage polymer particles comprise a) a water-occluded core comprising from 30 to 50 weight percent structural units of a salt of methacrylic acid and from 50 to 70 weight percent structural units of a nonionic monoethylenically unsaturated monomer, based on the weight of structural units of monomers in the water-occluded core;
- b) a polymeric shell having a Tg in the range of from 90° C. to 115° C.;
- and c) a layer of a film forming polymeric binder superposing the polymeric shell, which film forming polymeric binder has a Tg in the range of from −10° C. to 15° C., and comprises structural units of at least one monoethylenically unsaturated monomer, wherein the film forming polymeric binder is an acrylic or styrene-acrylic binder;
- wherein each of the nonionic monoethylenically unsaturated monomers of the water-occluded cores of the first and second multistage polymer particles are one or more acrylates or methacrylates selected from the group consisting of as methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate 2-ethylhexyl acrylate, methyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, lauryl methacrylate, and cyclohexyl methacrylate;
- and a monoethylenically unsaturated aromatic compound selected from the group consisting of styrene, α-methylstyrene, and 4-t-butylstyrene;
- wherein each of the polymeric shells of the first and second multistage polymer particles comprise from 89 to 93 weight percent structural units of styrene, and from 4 to 5 weight percent structural units of methyl methacrylate, from 0.9 to 2 weight percent structural units of cyclohexyl methacrylate, from 2 to 3 weight percent structural units of methacrylic acid, and from 0.1 to 0.5 weight percent structural units of allyl methacrylate;
- wherein the weight-to-weight ratio of structural units of monomers in the water-occluded core to the polymeric shell in the first and second multistage polymer particles is in the range of 1:10 to 1:20;
- the weight-to-weight ratio of the film forming polymeric binder to the sum of the polymeric shell and the structural units of monomers in the water-occluded core in the second multistage polymer particles is in the range of from 1.5:1 to 2.5:1;
- the weight-to-weight ratio of the first multistage polymer particles to the second multistage polymer particles is in the range of from 0.15:1 to 1.0:1;
- the z-average particle size of the first multistage polymer particles is in the range of from 200 nm to 2000 nm;
- and
- the z-average particle size of the second multistage polymer particles is in the range of from 300 nm to 750 nm.
13 more elements
Dependencies are inferred from the claim text.