Nitto Chemical Industry Co., Ltd.

Mitsubishi Rayon Company, Limited

Nitto Kagaku Kogyo Kabushiki Kaisha

Nitto Kagaku Kogyu Kabushiki Kaisha

Junsuke Yagi

Iwao Ohshima

Takeyuki Fujita

Michio Fukatsu

Koichi Orii

Yoshiro Ashina

Masashi Nishida

Naotake Watanabe

A process for preparing silica having a low silanol content which comprises heating amorphous silica in an atmosphere of a low partial pressure of water vapor to maintain the amorphous silica at a temperature in a range of from 600.degree. to 1000.degree. C. at a first heating step and then maintain at a temperature of 1200.degree. C. or more at a second heating step. The silica having a low silanol content obtained according to the present invention is advantageously used as a raw material for quartz glass, particularly as a raw material for preparing crucibles used to pull up silicon single crystals.

Process for preparing silica having a low silanol content

This invention deals with a process for manufacturing high purity silica which comprises making an aqueous alkali silicate solution into fine fibrous gel in a coagulant, treating the fibrous gel obtained with an acid-containing solution, and then with water to extract and remove impurities; and optionallly heating a resulting silica at a temperature of 1,000.degree. C. or higher. Thus obtained silica is preferably used as a filler, especially, the one for resin compositions for encapsulating electronic parts; etc.

Process for manufacturing high purity silica

A process for the selective production of dimethylamine in preference to mono- and trimethylamines by a catalytic vapor phase reaction of ammonia and methanol over a zeolite selected from mordenite, clinoptilolite and erionite is disclosed, wherein the improvement is characterized by the fact that the zeolite used has been contacted with steam at a temperature of 250.degree. to 700.degree. C.

Process for producing dimethylamine in preference to mono- and

Catalytic production of dimethylamine in preference to mono- and trimethylamine over a mordenite catalyst is disclosed, which mordenite is characterized by its alkali metal content.

Process for producing dimethylamine in preference to mono- or

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Yokohama, Japan

Junsuke Yagi