Chemistry: physical processes – Physical processes – Crystallization
Patent
1990-12-17
1994-03-22
Straub, Gary P.
Chemistry: physical processes
Physical processes
Crystallization
106463, 106464, 423430, 423432, C01F 534, C01F 524, C09C 102
Patent
active
052960021
ABSTRACT:
A form of calcium carbonate having a blocky rhombohedral crystal structure and properties including a surface area of from about 3 to about 15 m.sup.2 g, an average discrete particle size of from about 0.2 to about 0.9 micron, wherein the discrete particles have an aspect ratio less than about, 2:1 and a particle size distribution such that at least about 60 weight percent of the particles have a size within 50 percent of the equivalent discrete particle spherical diameter, suitable for use as a filler material in papermaking to improve the optical properties of the resulting paper, is disclosed. An accelerated heat-aging process, including embodiments thereof which utilize hydrothermal techniques, for rapidly producing this form of calcium carbonate, and a related form of calcium carbonate having a hexagonal prismatic crystal structure and the same properties, in large quantities to meet the demand of the papermaking industry, as well as a method for using these materials in papermaking, are also disclosed.
REFERENCES:
patent: 3126253 (1964-03-01), Podschus
patent: 4762588 (1988-08-01), Hirano et al.
Akers Lawrence C.
Jaeger Howard R.
Pfizer Inc.
Richardson Peter C.
Straub Gary P.
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