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AssigneesVictor Company of Japan, Ltd., Tokuyama Sekisui Industry Corporation, Limited
InventorsKazuhira Namikawa, Toshiaki Hamaguchi, Mutsuaki Nakamura, Akio Kuroda, Akio Hata, Noriki Fujii
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High density information records formed from conductive resin compositions which comprise a graft polymer obtained by subjecting vinyl chloride monomer to graft polymerization with a copolymer of ethylene and vinyl acetate having a content of vinyl acetate of not less than 35 wt % and a melt index up to 20 and prepared according to a solution polymerization technique. The conductive composition further comprises predetermined amounts of a conductive material and a lubricant of a specific type. The lubricant is an ester between aliphatic acid and alcohol having a hydroxyl value not larger than 15.
In a high density information record of the electrostatic capacitance type which comprises a record substrate on which signal information is recorded as geometric variations and which is made of a conductive resin composition comprising 100 parts by weight of a graft polymer between a copolymer of ethylene and vinyl acetate and monomeric vinyl chloride in a ratio by weight of 1 to 10:99 to 90, which copolymer has a content of vinyl acetate not less than 35 wt%, and 5 to 30 parts by weight of a conductive powder and 0.5 to 5 parts by weight of a lubricant dispersed in said graft polymer, the improvement wherein said copolymer is obtained by solution polymerization and has a melt index not larger than 20 and said lubricant is an ester between a fatty acid and an alcohol having a hydroxyl value not larger than 15.
Dependencies are inferred from the claim text.