Spray drying method for preparing kaolin as a pigment extender
AssigneePacemaker Corporation
InventorDennis W. Caton
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Abstract
Composite white pigments composed of titanium dioxide (TiO.sub.2) and kaolin are prepared by subjecting kaolin slurry to spray drying with injected gas to promote droplet fluffing and fragmentation. The slurry contains a hydrocolloid suspending agent and a cationic reagent for making the kaolin particles cationic. The frangible dry material thus produced can be blended with TiO.sub.2 particles to produce an extended TiO.sub.2 pigment.
Claims8
A method for preparing kaolin for use as a pigment extender, comprising:
- (a) preparing a sprayable slurry comprising an aqueous hydrocolloid suspension of calcined anionic white kaolin particles in admixture with a cationic reagent capable of binding to said kaolin particles and making them cationic;
- (b) subjecting said slurry to drying in a spray dryer by atomizing droplets of a pressurized mixture of said slurry with an added gas to promote droplet fluffing and fragmentation;
- and
- (c) collecting a frangible dry material from said spray drying which material is cationic and which binds in dry condition to anionic titanium dioxide.
The method of preparing a composite white pigment product composed of titanium dioxide (TiO.sub.2) and kaolin, comprising:
- (a) preparing a sprayable slurry comprising an aqueous hydrocolloid suspension of calcined anionic white kaolin particles in admixture with a cationic reagent capable of binding to said kaolin particles and making them cationic;
- (b) subjecting said slurry to drying in a spray dryer by atomizing droplets of a mixture of said slurry with pressurized air injected therein to promote droplet fluffing and fragmentation;
- (c) collecting a frangible dry material from said spray drying which material is cationic;
- and
- (d) blending portions of said cationic material with anionic titanium dioxide (TiO.sub.2) pigment particles by mechanically mixing to bring the dry kaolin material into intimate contact with TiO.sub.2 particles, said mixed blend containing composites of TiO.sub.2 and kaolin particles and being composed by weight of from 5 to 40% of kaolin together with from 60 to 95% of TiO.sub.2.
Dependencies are inferred from the claim text.