Shiraishi Kogyo Kaisha, Ltd.

Shiraishi Central Laboratories Co., Ltd.

Satoshi Kondo

Setsuji Edagawa

Hisashi Hasegawa

Hiroji Shibazaki

Takashi Deguchi

Ryogo Tsukisaka

Toshio Kaneguchi

Kazuo Ohnawa

Disclosed is a calcium carbonate which is 25 to 55 m.sup.2 /g in BET specific surface area, 5 to 110 in the ratio of BET specific surface area (m.sup.2 /g)/mean particle size (.mu.m), at least 120 ml/100 g in oil absorption as determined by the Ogura method and at least 1.8 g/g in water absorption, and process for preparing the same. The calcium carbonate is formulated into a coating composition for forming a heat-sensitive recording layer or intermediate layer of a heat-sensitive recording paper or for forming an ink-jet recording paper.

Calcium carbonate, calcium carbonate pigment, process for preparing

The invention provides calcium carbonate particles comprising a core and projections formed thereon, and process for preparing same. The calcium carbonates of this invention are useful as fillers and pigments for rubbers, plastics, papers, etc. because of their peculiar configuration and unique properties.

Calcium carbonate particles and processes for preparing same

Surface-treated calcium carbonate powders of this invention are easy to handle and highly dispersible in water, give slurries of high concentration and are useful as pigments and various other applications.

Calcium carbonate powders

Precipitated calcium carbonate of uniform particle size is produced by contacting a suspension of calcium hydroxide with a carbon dioxide-containing gas in three steps. The particle size of precipitated calcium carbonate can be optionally selected by suitably adjusting reaction conditions.

Process for preparing precipitated calcium carbonate

Cubic calcium carbonate crystals of uniform size are prepared by contacting with CO.sub.2 a starting aqueous suspension containing Ca(OH).sub.2 and cubic CaCO.sub.3 crystals less than 0.1.mu.m in size, adding Ca(OH).sub.2 to the suspension resulting from the first step and contacting the resultant mixture with CO.sub.2.

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Nishinomiya, Japan

Satoshi Kondo