Shin-etsu Chemical Co., Ltd.

Masanobu Nishimine

Susumu Ueno

Tsutomu Nakamura

Hirofumi Fukuoka

Yoichi Tanifuji

Daichi Todoroki

Kiyoshi Shirasuna

Yoshio Tomizawa

Hidekazu Uehara

Michiaki Sezai

Tomoya Ogata

Tomoyoshi Koike

Tomio Iwase

A method for manufacturing granulated silica. The method includes granulating silica powders each having a primary particle size of 5 to 50 nm by use of water, and hydrophobizing each surface of the silica powders with a silicon atom-containing hydrophobizing agent before or simultaneously with the granulation step.

Method for manufacturing granulated silica

A silicon oxide deposit is continuously prepared by feeding a powder feed containing silicon dioxide powder to a reaction chamber, heating the feed at 1,200-1,600&#xb0; C. to produce a silicon oxide vapor, delivering the vapor to a deposition chamber through a transfer line which is maintained at or above the temperature of the reaction chamber, for thereby causing silicon oxide to deposit on a cool substrate, and removing the silicon oxide deposit from the deposition chamber. Two deposition chambers are provided, and the step of delivering the vapor is alternately switched from one to another deposition chamber.

Method and system for the production of silicon oxide deposit

Particulate silica is prepared by feeding a gas mixture of an organohalosilane gas, a flammable gas capable of generating water vapor when burned, and a free oxygen-containing gas to a reaction chamber through a multiple-tube burner, whereby the organohalosilane is subjected to flame hydrolysis and oxidation reaction. The amount of the flammable gas fed is 0.5-9 mol per mol of the organohalosilane and such that the amount of water vapor resulting from combustion of the flammable gas is 1-6 times the stoichiometric amount, and the gas mixture is fed to the center tube of the burner such that it may have a linear velocity at the outlet of 50-120 m/sec, calculated in the standard state. The resulting silica has a surface area of 100-400 m/g and a narrow particle size distribution of primary particles and ensures the transparency of silicone rubber filled therewith.

Particulate silica and its preparation

Crude fumed silica resulting from pyrogenic hydrolysis is purified by continuously feeding particulate silica and steam or a mixture of steam and air in a steam/air volume ratio of at least 1/2 through an upright column from its bottom toward its top for forming a fluidized bed within the column at a gas linear velocity of 1 to 10 cm/sec. and a temperature of 250.degree. to 400.degree. C., whereby steam deprives the particulate silica of the halide borne thereon, and removing fine particulate silica from which the halide has been eliminated from the top of the column. Using a simple apparatus, pure fine particulate silica is collected at a low cost of energy consumption.

Method for porifying fine particulate silica

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Tokyo, Japan

Masanobu Nishimine