Idemitsu Kosan Company, Limited

Idemitsu Petrochemical Co., Ltd.

Tatsuya Tomioka

Hiroshi Kawato

Munehiro Chosa

Shigeru Murakami

Norio Ogata

Kenkichi Takahashi

Tetsuro Takeya

The present invention relates to a polycarbonate resin that has a viscosity average molecular weight of from 10,000 to 17,000 and has characteristic features in an iron content, a free total phenol content, a content of a releasing agent, a fraction of hydroxyl end groups, aH-NMR spectrum or the like. The polycarbonate resin has less defects due to flash without increase of an addition amount of a releasing agent to an unnecessary level and therefore is suitable for a material of an optical disk substrate.

Polycarbonate resin for optical disk substrate and optical disk substrate

The present invention relates to a polycarbonate resin that has a viscosity average molecular weight of from 10,000 to 17,000 and has characteristic features in an iron content, a free total phenol content, a content of a releasing agent, a fraction of hydroxyl end groups, a H-NMR spectrum or the like. The polycarbonate resin has less defects due to flash without increase of an addition amount of a releasing agent to an unnecessary level and therefore is suitable for a material of an optical disk substrate.

There is disclosed a process for preparing a resin composition for powder molding, comprising 50 to 97 wt % of a metal or alloy powder and 50 to 3 wt % of a thermoplastic resin having heat resistance and crystallinity, which process comprises dissolving the thermoplastic resin having heat resistance crystallinity in a solvent and at the same time, dispersing therein at least one metal or alloy powder selected from iron, brass, nickel silver, stainless steel and aluminum, having an average particle diameter of not more than 500 .mu.m to thereby prepare a mixture. In addition, there is disclosed a process for producing a powder molded product which comprises cold compressing molding the above resin composition and then heating the molding at a temperature not less than the melting point of the thermoplastic resin. This powder molded product has excellent dimensional stability against heat, chemical resistance, and mechanical strength.

Methods for preparing magnetic powder material and magnet, process for

There is disclosed a process for preparing a resin composition for powder molding, comprising 50 to 97 wt % of a metal or alloy powder and 50 to 3 wt % of a thermoplastic resin having heat resistance and crystallinity, which process comprises dissolving the thermoplastic resin having heat resistance crystallinity in a solvent and at the same time, dispersing therein at least one metal or alloy powder selected from iron, brass, nickel silver, stainless steel and aluminum, having an average particle diameter of not more than 500 .mu.m to thereby prepare a mixture. In addition, there is disclosed a process for producing a powder molded product which comprises cold compressing molding the above resin composition and then heating the molding at a temperature not less than the melting point of the thermoplastic resin. This powder molded product has excellent dimensional stability against heat, chemical resistance, and mechanical strength. Also, there is disclosed a process for producing a magnetic powder material wherein there is added to a mixture containing a crystalline thermoplastic resin dissolved therein and magnetic powder dispersed therein a bad solvent for the resin to effect precipitation of the resin from the solution system and the resin is adhered or coated onto the magnetic powder. Other methods for forming the magentic powder material are disclosed as a resin-bonded magnetic obtained from such magnetic powder material.

Disclosed is a polyester carbonate containing imido groups comprising recurring units represented by the following formula: ##STR1## and recurring units represented by the following formula:

Polyester carbonate containing imido groups and method of preparing the

Polyester polymers consisting essentially of repeating units having the formula ##STR1## repeating units having the formula

Novel polyester polymers

A flame retardant polycarbonate resin composition comprising a polycarbonate resin, a nuclear substituted benzoic acid containing at least one substituent selected from the group consisting of thiosalicylic acid and dihydroxy benzoic acid, and tetrabromobisphenol A or ##STR1## .

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Chiba, Japan

Tatsuya Tomioka