Nippon Zeon Company, Ltd.

Victor Company of Japan, Limited

Hitachi, Ltd.

Noboru Watanabe

Yoichiro Kubo

Yasuo Ishizaka

Kazuo Kimura

Eiichiro Imaoka

Yoshiaki Aimura

Sachio Hayashi

Takao Kato

Akira Hirota

Motofumi Oyama

Yutaka Ichinoi

Osamu Kobayashi

Ikuo Matsumoto

Akira Horiki

Tetsuo Takemura

Takayuki Deno

Tsutomu Yashiro

Hideyoshi Shimoda

Masaru Hanayama

Takumu Tada

Sunao Saitoh

Toshimitsu Saitou

Kazuyoshi Watanabe

Hideyoshi Shomoda

Tsuyoshi Nakagawa

A magnetic recording medium has a substrate and a magnetic layer formed on the substrate. The magnetic layer includes magnetic powder and a binder for binding the magnetic powder on the substrate. The binder includes at least a resin component containing at least an aminoquinone structure selected from an aminoquinone structure group shown with formulas (1-1a), (1-1b), (1-3a) and (1-3b) as a constitutional unit and at least a polar group selected from a group shown with a formula (1-2) in a composition of the resin component. Thus, the magnetic recording medium has excellent corrosion resistance of the magnetic powder and excellent conservation and running durability.

Magnetic recording medium and binder for use with magnetic coating in

A magnetic recording medium has a substrate and an non-magnetic underlayer formed on the substrate and a magnetic layer formed on the non-magnetic layer. The magnetic layer include a magnetic powder and a binder for binding the magnetic powder on the non-magnetic layer. The binder includes at least a resin component containing at least an aminoquinone structure selected from an aminoquinone structure group shown with formulas (1-1) and (1-2) as a constitutional unit. As the magnetic powder, a metal magnetic powder mainly made of Fe and having a saturation magnetization .sigma.s is used. The magnetic layer has a saturation flux density Bm of 3500 to 5000 G and a coercive force of 1800 to 3000 Oe and a surface roughness SRa of 1 to 10 nm and a thickness of not more than 1.0 .mu.m.

Magnetic recording medium

A polymer composition comprising a polymer or a highly saturated polymer, an organic peroxide and a maleimide derivative, said polymer being produced by radical polymerization using a sulfur-free compound as an emulsifier and a terpene type compound as a molecular weight modifier and said highly saturated polymer being obtained by hydrogenating said polymer.

Polymer composition

An apparatus for producing a frequency-multiplex signal on the basis of a plurality of signals so as to record the produced frequency-multiplex signal on a recording medium, second signal having a frequency lower than that of the first signal. The apparatus includes a multiplying circuit for multiplying the frequency of the second signal by 2 and an amplitude-modulator for multiplying the first signal by the output signal of the multiplying circuit. Also included in the apparatus is an adder for adding the second signal to the output signal of the amplitude-modulator, the output signal of the adder being recorded as the frequency-multiplexing signal on the recording medium.

Recording of frequency-multiplex signal on recording medium

A nitrile group-containing, highly saturated copolymer rubber is disclosed, the copolymer chain of which is comprised of (1) 5 to 40% by weight of units of an unsaturated nitrile monomer, (2) 1 to 80% by weight of units of a monomer selected from a fluorine-free unsaturated carboxylic acid ester monomer and a fluorine-containing vinyl monomer and (3) up to 20% by weight of units of a conjugated diene monomer, with the balance being (4) units of a hydrogenated conjugated diene monomer, wherein the sum of the contents of the monomer units (1) and (2) is 30 to 90% and the sum of the contents of the monomer units (3) and (4) is 10 to 70% by weight. This copolymer rubber results in a rubber composition having an improved cold resistance.

Nitrile group-containing highly saturated copolymer rubber and rubber

A rubber composition comprising a nitrile group-containing hydrocarbon rubber and a vulcanizing system, characterized in that the iodine value of said rubber does not exceed 120 and the pH of the tetrahydrofuran solution of said rubber is at least 5.

Method of vulcanizing rubber at pH 5 to 10

A perpendicular magnetic recording medium comprises a recording medium base, a lower layer formed on the recording medium base, and an upper layer formed on the lower layer. The lower layer is made of a first material including cobalt, chromium and one or more elements other than cobalt and chromium. On the other hand, the upper layer is made of a second material including cobalt, chromium and one or more elements other than cobalt and chromium. A quantity of the one or more elements added to cobalt and chromium making up the second material is less than a quantity of the one or more elements added to cobalt and chromium making up the first material.

Perpendicular magnetic recording medium

A perpendicular magnetic recording medium comprises a recording medium base, a lower layer formed on the recording medium base, and an upper layer formed on the lower layer. The upper layer is made of cobalt-chromium, and the lower layer at least includes cobalt and chromium.

A perpendicular magnetic recording and reproducing system records and reproduces a signal on and from a perpendicular magnetic recording medium comprising a magnetic layer which is made from one magnetic material and is constituted by a layer having a low coercivity and a layer having a high coercivity on top of the layer having the low coercivity, by use of a ring core head and utilizes the layer having the low coercivity as a high permeability layer and the layer having the high coercivity as a perpendicular magnetization layer.

Perpendicular magnetic recording and reproducing system

A perpendicular magnetic recording medium comprises a recording medium base, a low coercivity layer formed on the recording medium base and having a low coercivity in an in-plane direction thereof, and a high coercivity layer formed on the low coercivity layer and having a high coercivity in a direction perpendicular to a surface of the low coercivity layer. The low coercivity layer and the high coercivity layer are formed from the same magnetic material and constitute a magnetic layer. A method of manufacturing this perpendicular magnetic recording medium comprises a single magnetic layer forming process of successively and continuously forming the low coercivity layer and the high coercivity layer on the recording medium base by using the same magnetic material as a depositing material.

Perpendicular magnetic recording medium and manufacturing method thereof

A heat-resistant and oil-resistant rubber composition comprising a nitrile group-containing rubber having an iodine value of not more than 120 and a nitrile group-containing liquid polymer having an iodine value of not more than 120.

Oil-resistant rubber composition

An oil- and heat-resistant rubber composition comprising a nitrile group-containing hydrocarbon rubber having an iodine number of not more than 120 and a fluorine-containing rubber.

Oil- and heat-resistant rubber composition comprising nitrile containing

A rubber composition having improved steam resistance comprising a nitrile group-containing hydrocarbon rubber having an iodine number of not more than 120, an organic peroxide vulcanizer and a crosslinking coagent, the amount of said crosslinking coagent being 8 to 30 parts by weight per 100 parts by weight of said rubber.

Growing community of inventors

Yokohama, Japan

Noboru Watanabe