Idemitsu Petrochemical Co., Ltd.

Haruki Kai

Tohru Nishi

Takao Inokuchi

Nobuo Kusamoto

Kazuhisa Kaneda

Yasuji Kawamura

Kazuo Minato

A powdered leather which is composed of at least 85% by weight of cortex, at most 2% by weight of oil and fat, and at most 0.5% by weight of Na.sup.+ and Ca.sup.2+ ions capable of being eluted by water and which has an average particle size (D.sub.50) of at most 7 .mu.m, a standard deviation of the average particle size being at most 3 .mu.m. With this powdered leather, it is possible to thin films, coatings, fibers, etc. which would hardly be deteriorated with time. The powdered leather is produced by providing a powdered leather raw material, grinding the raw material into coarse particles, drying the coarse particles, defatting the dried coarse particles using a solvent, removing the residual solvent from the defatted coarse particles, rinsing the resultant coarse particles, dewatering the rinsed coarse particles, swelling the dewatered coarse particles in steam, redrying the swelled coarse particles, pulverizing the redried coarse particles, classifying the pulverized particles into fine powder and coarse powder, and repulverizing the fine powder so as to have an average particle size (D.sub.50) of at most 7 .mu.m.

Powdered leather and method of producing the same

A rubber composition containing a powdered leather of a dispersion mixture comprising from 10 to 400 parts by weight of a powdered leather with a skin component of greater than 75% by weight, a total amount of Na.sup.+ ions and Ca.sup.2+ ions extractable with water of less than 0.5% by weight and an average grain size D.sub.50 of from 10 .mu.m to 250 .mu.m, and 100 parts by weight of rubber obtained from a raw material for the powdered leather by performing coarse pulverization, water washing, dewatering, steams swelling, drying and powderization and then separation into particles of a desired average grain size depending on the purpose of use, as well as a molding product obtained from the rubber composition.

Rubber composition containing powdered leather and molding products

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Ichihara, Japan

Haruki Kai