Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1990-12-17
1993-07-13
Straub, Gary P.
Paper making and fiber liberation
Processes and products
Non-fiber additive
106464, 423430, C09C 102, C01F 524, D21H 1764
Patent
active
052270254
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), Podschu
patent: 3920800 (1975-11-01), Harris
patent: 4420341 (1983-12-01), Ferrigno
patent: 4732748 (1988-03-01), Stewart et al.
patent: 5043017 (1991-08-01), Passaretti
Kunesh Charles J.
Passaretti June D.
Akers Lawrence C.
Jaeger Howard R.
Pfizer Inc
Richardson Peter C.
Straub Gary P.
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