Hitachi Chemical Company, Ltd.

Takeyoshi Watanabe

Hideji Kuwajima

Kazuyoshi Shike

Juichi Sakurada

Hirofumi Mizoguchi

A reconstituted mica material produced by sheet forming a slurry containing mica flakes prepared by disintegrating unfired mica and comprising (i) mica flakes having a particle size of 1.7 mm or more and an aspect ratio of 150 or more, (ii) mica flakes having a particle size of 1.0 mm or more and less than 1.7 mm and an aspect ratio of 150 or more, (iii) mica flakes having a particle size of 0.25 mm or more and less than 1.0 mm and an aspect ratio of 100 or more, and (iv) mica flakes having a particle size of less than 0.25 mm and an aspect ratio of 100 or more, in definite ranges, gives reconstituted mica prepreg materials, reconstituted mica products and insulated coils having excellent mechanical and electrical properties.

Reconstituted mica materials, reconstituted mica prepreg materials,

A reconstituted mica material produced by sheet forming a slurry containing mica flakes prepared by disintegrating unfired mica and comprising (i) mica flakes having a particle size of 1.0 mm or more and an aspect ratio of 150 or more, (ii) mica flakes having a particle size of 0.25 mm or more and less than 1.0 mm and (iii) mica flakes having a particle size of less than 0.25 mm, in definite ranges, gives reconstituted mica prepreg materials, reconstituted mica products and insulated coils having excellent mechanical and electrical properties.

Mica flakes are disintegrated to mica scales having a diameter of 10 mm or less and a ratio of diameter/thickness of 100-1000 by using an apparatus and a method comprising bringing about coarse size reduction followed by size reduction of the mica flakes by high-pressure jets of water, if desired together with high-pressure jets of gas, separating mica scales from mica flakes by vertical classification followed by horizontal classification, and taking out the mica scales as a slurry while recycling nondisintegrated mica flakes to size reduction. The slurry of mica scales is used for making mica paper.

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Hitachi, Japan

Takeyoshi Watanabe