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AssigneeFuji Photo Film Co., Ltd.
InventorsYuichiro Murayama, Masaki Satake, Hiroshi Hashimoto, Tsutomu Okita
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In a binder for a magnetic recording medium for forming a magnetic layer with ferromagnetic powder dispersed therein being arranged on a non-magnetic support member, whereby said binder consists of a polyurethane resin, which is a reaction product of diol and organic diisocyanate as principal materials, said polyurethane resin contains a short-chain diol having cyclic structure by 17 to 40 weight %, and said polyurethane resin contains a long-chain diol comprising 1.0 to 5.0 mmol/g of ether group to total urethane resin by 10 to 50 weight %. According to a binder for a magnetic recording medium and a magnetic recording medium using said binder of the present invention, good dispersion property, high running durability and preservation property can be obtained.
A magnetic recording medium comprising a magnetic layer formed on a non-magnetic support member, said magnetic layer comprising ferromagnetic powder and a binder comprising a polyurethane resin which is a reaction product of diol and organic diisocyanate, wherein said diol comprises short chain diol and long chain diol, said short-chain diol has a cyclic structure and said short chain diol forms 17 to 40 weight % of said polyurethane resin, said long-chain diol contains 1.0 to 5.0 mmol/g of an ether group and said long-chain diol forms 10 to 50 weight % of said polyurethane resin, and the thickness of said magnetic layer is 1 .mu.m or less, wherein said short-chain diol has a molecular weight less than 500, and said long-chain diol has a molecular weight of 500 to 5,000.
Dependencies are inferred from the claim text.