Layered composite pigments and method of making same
OwnerMichael Whalen-Shawinventor
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Abstract
Composite pigments and processes for making the same, useful as partial or total replacement for pigments conventionally employed in paper, paper coatings, paint, ink, and in rubber, are disclosed. The composite pigments comprise one or more synthetic or natural core particles having adsorbed on the surface thereof a polymeric dispersant having a positive or negative charge, and one or more natural or synthetic co-particles having adsorbed on the surface thereof a polymeric dispersant having a positive or negative charge opposite the charge of the core particles. The composite pigments provide improved optical and other properties.
Claims29
A composite pigment comprising one or more types of core pigment particles and one or more types of co-pigment particles prepared by mixing core pigment particles with co-pigment particles, the core pigment particles prior to mixing comprising adsorbed on their surface a dispersing agent consisting essentially of a cationic polyelectrolyte dispersant or an anionic polyelectrolyte dispersant and the co-pigment particles prior to mixing comprising adsorbed on their surface of dispersing agent consisting essentially of an anionic polyelectrolyte dispersant or a cationic polyelectrolyte dispersant which is opposite in charge to the dispersant on the core pigment particles and which provides the co-pigment particles with a charge opposite the charge of the core pigment particles, the co-pigment particles in the composite pigment being electrostatically bound to the core pigment particles, the core pigment particles and the co-pigment particles having an average particle size greater than 0.1 micron.
A composite pigment dispersion comprising one or more types of core pigment particles and one or more types of co-pigment particles prepared by mixing core pigment particles with co-pigment particles, the core pigment particles prior to mixing comprising adsorbed on their surface a dispersing agent consisting essentially of a cationic polyelectrolyte dispersant or an anionic polyelectrolyte dispersant and the co-pigment particles prior to mixing comprising adsorbed on their surface a dispersing agent consisting essentially of an anionic polyelectrolyte dispersant or a cationic polyelectrolyte dispersant which is opposite in charge to the dispersant on the core pigment particles and which provides the co-pigment particles with a charge opposite the charge of the core pigment particles, the co-pigment particles in the composite pigment dispersion being electrostatically bound to the core pigment particles, the core pigment particles and the co-pigment particles having an average particle size greater than 0.1 micron.
A method of preparing composite pigments comprising the steps of:
- obtaining a suspension of core pigment particles comprising adsorbed on the surface thereof a dispersing agent consisting essentially of a cationic polyelectrolyte dispersant or an anionic polyelectrolyte dispersant;
- obtaining a suspension of co-pigment particles comprising adsorbed on the surface thereof a dispersing agent consisting essentially of an anionic polyelectrolyte dispersant or a cationic polyelectrolyte dispersant which is opposite in charge to the dispersant on the core pigment particles and which provides said co-pigment particles with a charge opposite the charge of the core pigment particles;
- and
- admixing said suspensions wherein the co-pigment particles electrostatically bind to the core pigment particles;
- said core pigment particles and said co-pigment particles having an average particle size greater than 0.1 micron.
Dependencies are inferred from the claim text.