Hoechst Celanese Corporation

Hoechst Aktiengesellschaft

Gerd Wingefeld

Gunther R Schimmel

Alexander Tapper

Hongkyu Kim

O Richard Hughes

Hans-Peter Rieck

Michael Kotzian

Walter P Hassinger

Cogranulates of high bulk density which easily disintegrate in water and comprise aluminosilicates and crystalline sodium silicates having a layered structure. The aluminosilicates contained therein are those of the formula

Process for the peparation of cogranulates comprising aluminosilicates

Provided is an injection moldable composition suitable for forming ceramic or metallic greenbodies. The composition comprises in combination an inorganic or metallic filler in an amount of from about 63 volume percent to about 92 volume percent, a binding organic matrix resin, and an organosilane processing reagent represented by the general formula:

Injection moldable ceramic and metallic compositions and method of

To prepare crystalline sodium silicates having a laminated structure, a molar ratio of SiO.sub.2 to Na.sub.2 O of (1.9 to 2.1) 1 and a water content of less than 0.3% by weight from a water glass solution which has a solids content of at least 20% by weight and is obtained by reaction of sand with sodium hydroxide solution in a molar ratio of SiO.sub.2 : Na.sub.2 O of (2.0 to 2.3) : 1, the water glass solution is treated with hot air of 200.degree. to 300.degree. C. in a spray drying zone to form a pulverulent, amorphous sodium silicate having a water content (determined as the loss on ignition at 700.degree. C.) of 15 to 23% by weight. The pulverulent, amorphous, water-containing sodium silicate is first ground, preferably to particle sizes of 1 to 50 .mu.m, before it is introduced into an inclined rotary tubular oven and treated in this in countercurrent with flue gas at temperatures of more than 500.degree. to 850.degree. C. to form crystalline sodium silicate. The sodium silicate issuing from the rotary tubular oven is first comminuted to particle sizes of 0.1 to 12 mm and finally ground to particle sizes of 2 to 400 .mu.m.

Process for the preparation of sodium silicates

A polyacetal binder is removed from an extruded or injection molded ceramic green body in less than 25 hours by a variable heating rate schedule in which the heating rate is reduced when the temperature of the green body reaches the point at which isothermal degradation of the polyacetal binder can take place and wherein at least 80 wt. % of the binder can be removed. In air, the isothermal removal of the binder can take place within the range of 160.degree.-220.degree. C. while in nitrogen the range is from about 300.degree.-360.degree. C.

Process for removing polyacetal binder from molded ceramic greenbodies

A process for rapidly removing the binder from a greenbody composed of a sinterable powder dispersed within a polyacetal binder is achieved by contacting the molded ceramic greenbody with an acid which depolymerizes the polyacetal binder.

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Hofheim, Germany

Gerd Wingefeld