Shin-etsu Chemical Co., Ltd.

Tokuji Abe

Susumu Ueno

Kiyoshi Imada

Michinori Tsuchida

Tadashi Amano

Toshihide Shimizu

Ichiro Kaneko

Hajime Kitamura

A polyvinyl chloride resin-based composition can be imparted with improved thermal stability of compounding the same with a polygylcerin in an amount of 0.01 to 0.5% by weight based on the resin even when the composition is compounded with a heat stabilizer having relatively low effectiveness although the use of such a heat stabilizer is desirable in respect of the physiological inertness. Similar improving effects on the thermal stability of a polyvinyl chloride resin-based composition can be obtained when the resin is prepared by suspension-polymerizing vinyl chloride monomer in an aqueous medium containing a polyglycerin.

Polyvinyl chloride resin composition having improved thermal stability

The invention provides a very simple but effective means for preventing surface oxidation of fine metal powders by coating the metal powder with an organic dye. This method of surface-oxidation prevention is particularly useful for the preparation of a so-called plastic magnet which is prepared by uniformly blending a dye-coated fine powder of a magnetic alloy such as a rare earth-cobalt based permanent magnet with a thermoplastic resin such as a nylon or polyphenylene sulfide resin followed by molding the resin-powder blend into a magnet form. In addition to the remarkably improved magnetic properties of the thus prepared plastic magnets as a result of high loading and absence of degradation by oxidation, the danger of spontaneous ignition of the magnet powder in molding can be eliminated almost completely. Surface treatment of the dye-coated magnet powder with a silicone fluid gives further improved results.

Plastic magnets impregnated with a dye-coated magnet alloy powder

The plastic magnet composition provided by the invention comprises a thermoplastic resin as a binder and a powder of a metallic or alloy-type magnet which is coated on the particle surface with a phosphorus-containing compound having at least one phosphorus-to-oxygen linkage in a molecule such as phosphoric acid and related compounds. By virtue of the surface coating, the magnet powder is freed from the degradation by air oxidation and the danger of ignition in the molding process so that plastic magnets of high performance can be readily manufactured with safety. The advantages of the coating layer are further increased when the coating layer is formed of a combination of the phosphorus-containing compound and an organic dye compound. An overcoating on the thus coated magnet powder with an organopolysiloxane has an effect of increased lubricity.

Composition for plastic magnets

A novel method is proposed for improving the surface properties or, in particular, for reducing accumulation of static electricity on the surface of a shaped article of a vinyl chloride-based resin. The inventive method comprises first exposing the surface of the shaped article to low temperature plasma of a gas having no polymerizability in plasma and then bringing the plasma-treated surface into contact with a liquid which is inert to the resin, e.g. water, or an aqueous solution containing a surface active agent. The effect of the inventive method is so strong and durable that the treated surface remains anti-static even after 12 months after the treatment.

Method for improving surface properties of shaped articles of polyvinyl

Gramophone records made of a vinyl chloride based resin are subjected to a treatment with low temperature plasma of a gas having no polymerizability in the plasma condition. A markedly improved anti-static effect is imparted to the surface of the gramophone record which also becomes highly resistant to wearing so that the signal/noise ratio in playing of the gramophone record is remarkably improved even after many times of repeated playing of the record.

Growing community of inventors

Omiya, Japan

Tokuji Abe