Shin-etsu Chemical Co., Ltd.

Makoto Suzuki

Osamu Matsumoto

Shigehiro Hoshida

Minoru Shigemitsu

Hideo Yoshikoshi

Toshimichi Koga

The invention discloses a method for counting foreign matter particles in a vinyl chloride resin powder comprising the steps of: forming an aqueous dispersion of the resin particles in a vessel having a transparent bottom, allowing the particles to settle forming a layer together with the foreign matter particles and viewing the layer of the deposited particles through the transparent bottom of the vessel to count the foreign matter particles in the deposited layer. The invention also provides an apparatus system for automatically counting foreign matter particles which comprises a vessel having a transparent bottom, a feed means for the resin powder, a water supply means, a stirrer means to form an aqueous dispersion in the vessel, a viewing means such as a CCD camera for recording the bottom image of the deposited layer through the transparent bottom of the vessel, and a control means for bringing the various parts of the system into a sequential linkage motion.

Method for counting foreign matter particles in vinyl chloride-based resin powder and apparatus system therefor

A resin composition for low expansion moldings which comprises (A) 20 to 80 parts by weight of a vinyl chloride resin having an average degree of polymerization of from 500 to 1700 and (B) correspondingly from 80 to 20 parts by weight of a copolymer made of 60 to 90 parts by weight a polymerizable monomer mixture consisting of 20 to 40 wt % of acrylonitrile, 20 to 60 wt % of .alpha.-methylstyrene and 20 to 40 wt % of styrene and, correspondingly, 40 to 10 parts by weight of a crosslinked acrylic rubber. The resin composition further comprises (C) 0.5 to 30 parts by weight of an acrylic resin having a reduced viscosity of not less than 3.0 dl/g when measured by use of a chloroform solution of the acrylic resin at a concentration of 0.1 g/100 ml, (D) 0.1 to 10 parts by weight of a thermally decomposable rosining agent, and (E) from 1 to 10 parts by weight of a stabilizer, each based on 100 parts by weight of a mixture of the components (A) and (B).

Resin composition for low expansion moldings

In preparing a matte vinyl chloride polymer by suspension polymerizing a monomeric charge comprising monomeric vinyl chloride in an aqueous medium, polymerization is started in the presence of 0.05-0.25 part by weight of diallyl phthalate per 100 parts by weight of the monomeric charge, and polymerization is continued while adding 0.01-0.15 part by weight of 1,6-hexanediol di(meth)acrylate per 100 parts by weight of the monomeric charge when the rate of polymerization is in the range of 20-60%. There is produced a matte vinyl chloride-diallyl phthalate copolymer having a tetrahydrofuran-insoluble gel content of 0.5-2.5% by weight in a reproducible manner. A composition prepared by blending the copolymer with a plasticizer has minimized fish-eyes and improved matting effect.

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Ibaraki-ken, Japan

Makoto Suzuki