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US 8,283,404 B2Granted
Opacifying pigment particle
AssigneeRohm and Haas Company
InventorsNathan T. Allen, Andrew G. Batzell, Ward T. Brown, Karl A. Bromm
Life of this patent
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Abstract
An opacifying pigment that includes a pigment particle having an average particle diameter of from 0.005 to 5 microns and an index of refraction of at least 1.8 such as, for example TiO2, at least partially encapsulated in polymer is provided. Also provided are processes for forming the encapsulated pigment particle and compositions including the encapsulated pigment particle.
Claims12
An opacifying pigment encapsulated in polymer comprising:
- 1) a pigment particle having an average particle diameter of from 0.005 to 5 microns and an index of refraction of at least 1.8;
- 2) from 0.1% to 25% by weight, based on the weight of the pigment particle, of a water-soluble first polymer, the molecular weight of which is controlled by 0 to 10 weight percent, based on the weight of the water-soluble first polymer, of an alkyl mercaptan or an alcohol or a halogenated compound, which water-soluble first polymer consists essentially of:
- a) at least three moieties of a sulfur acid monomer or a salt thereof;
- and
- b) structural units of at least one other monomer selected from the group consisting of an amine functional monomer;
- styrene;
- vinyl toluene;
- vinyl acetate;
- vinyl versatate;
- acrylonitrile;
- (meth)acrylamide;
- C1-C40 esters of (meth)acrylic acid;
- alcohol containing monomers;
- and ethylenically unsaturated mono-, di- and trialkyl esters of ethylenically unsaturated carboxylic acids and anhydrides;
- and
- 3) from 10% to 200% by weight, based on the weight of the pigment particle a second polymer that at least partially encapsulates the pigment particle.
13 more elements
A process comprising:
- 1) dispersing opacifying pigment particles having an average particle diameter of from 0.005 to 5 microns and an index of refraction of at least 1.8;
- with a water-soluble first polymer, the molecular weight of which is controlled by 0 to 10 weight percent, based on the weight of the water-soluble first polymer, of an alkyl mercaptan or an alcohol or a halogenated compound, which water-soluble first polymer consists essentially of:
- a) at least three moieties of a sulfur acid monomer or a salt thereof;
- and
- b) structural units of at least one other monomer selected from the group consisting of an amine functional monomer;
- styrene;
- vinyl toluene;
- vinyl acetate;
- vinyl versatate;
- acrylonitrile;
- (meth)acrylamide;
- C1-C40 esters of (meth)acrylic acid;
- alcohol containing monomers;
- and ethylenically unsaturated mono-, di- and trialkyl esters of ethylenically unsaturated carboxylic acids and anhydrides;
- and
- 2) contacting the dispersion of step 1) with an aqueous dispersion of a monomer emulsion under emulsion polymerization conditions to form opacifying pigment particles at least partially encapsulated in 10 to 200 weight percent, based on the weight of the pigment particles, of a second polymer.
13 more elements
Dependencies are inferred from the claim text.