Fuji Silysia Chemical Ltd.

Fuji-davison Chemical Ltd.

Kirin Brewery Kabushiki Kaisha

Nobuki Watanabe

Mutsuhiro Ito

Yuzo Horinouchi

Takashi Matsui

Sakio Takahashi

Masayuki Arimura

Yuji Takahashi

Eiji Kanemaru

The present invention provides a novel filter aid which has excellent filtration properties and forms a stable cake layer on a filter member. The filter aid includes a flake-like, scale-like, or rod-like silica gel as a primary component thereof. The silica gel is approximately 5 through 100 micrometer in grain diameter and has a pore volume of approximately 0.2 through 1.5 ml/g and a specific surface area of approximately 100 through 1,000 m.sup.2 /g.

Filter aid including specific silica gel

This invention provides a method for manufacturing silica gels in a form of scales or needles having a pore volume and a specific surface area being relatively large and being controlled. Silicic acid sol is frozen, crystallized and deposited in gaps among crystal faces of crystals of solvent of the sol, thus obtaining the frozen silica hydrogels in the form of scales or needles. After unfreezing the frozen silica hydrogels, a hydrothermal polymerization is carried out. Subsequently, the silica hydrogels are dried, thus obtaining the silica gels in the form of scales or needles. Furthermore in the invention, by controlling the gelation time period of silica sol, the silica gels with their configuration controlled can result from even inexpensive silica sol. The invention has the advantage that a freeze-drying step is not required: just through freezing, unfreezing, washing and hydrothermal polymerization steps, the physical properties of the silica gels can be controlled.

Silica gel manufactured by a hydrothermal polymerization following

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Hyuga, Japan

Nobuki Watanabe