Sony Corporation

Shin-etsu Chemical Co., Ltd.

Nippon Polyurethane Industry Co., Ltd.

Masashi Somezawa

Hiroshi Yoshioka

Yoshinobu Ninomiya

Shigeo Kimura

Yoshio Inoue

Minoru Takamizawa

Kaoru Nakajima

Akira Hashimoto

Kunio Kobayashi

Yuji Hinoto

Kiyokazu Oiyama

Masakazu Muroyama

Yutaka Takei

Tatsuo Shimizu

Shin Konishi

Shigetaka Higuchi

Mitsuhiro Yoshida

Seiichi Miyai

Ryoji Chubachi

Yoshihisa Kawamura

Isao Ishibashi

Masatake Katagiri

A magnetic recording medium having a magnetic layer on one surface of a non-magnetic base and having as required a backcoat layer on the other surface, having at least one of p-tolyldiiodemethylsulfone, 2,3,3-triiodoallyl alcohol and 2-methoxycarbonylaminobenzimidazole and 2-methoxycarbonylaminobenzimidazolium salt as an anti-fungus agent on or in the magnetic layer and/or the backcoat layer.

Magnetic recording medium utilizing a fungicide

Magnetic recording medium

A magnetic recording medium comprised of a non-magnetic substrate and a magnetic layer formed on one surface of the substrate and consisting essentially of a binder and magnetic powders. As the binder, a thermoplastic polyurethane-urea resin is employed, in which hydrophilic polar groups are introduced. The thermoplastic polyurethane-urea resin contains urethane and urea bonds in the molecule thereof and may be synthesized from a long-chain diol with a molecular weight of about 500 to 5000, a short-chain diol with a molecular weight of about 50 to 500, an organic diisocyanate and an organic diamine. Examples of the thus introduced hydrophilic polar groups are: ##STR1##

A magnetic recording medium has a magnetic layer consisting essentially of a binder and magnetic particles on one surface of a non-magnetic substrate. The thermoplastic polyurethane-urea resin in which unsaturated bonds sensitive to radiation are introduced is used as the binder. The thermoplastic polyurethane-urea resin in which the radiation-sensitive unsaturated bonds are introduced has both urethane and urea bonds in the molecular structure thereof. It is synthesized from long chain diol with a molecular weight of approximately 500 to 5000, a short chain diol with a molecular weight of approximately 50 to 500, an organic diisocyanate, an organic diamine, and a compound containing radiation-sensitive unsaturated double bonds, and cured by radiation. The thermoplastic polyurethane-urea resin in which not only the radiation-sensitive double bonds but also hydrophilic polar groups are introduced may also be used as the binder. These hydrophilic polar groups may for example include --SO.sub.3 M, --OSO.sub.3 M, --COOM, and ##STR1##

The magnetic recording medium comprises a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder. The binder contains a binder component having an absorbed amount of the binder component to a surface of the magnetic powder more than 1.5 mg per square meter of a surface area of the powder measured in 3 weight % solution in methyl ethyl ketone solvent, and the magnetic layer has a pigment volume concentration of the magnetic powder between 60 and 75%. The binder provides an improved strength and high pigment volume concentration of magnetic coating layer, and improved durability of the magnetic recording medium.

Method for manufacturing a magnetic recording medium

Electron radiation curable resin

Improved magnetic media comprising a non-magnetic substrate and a magnetic layer formed on at least one side of the substrate. The magnetic recording media are provided in a variety of ways with a specific type of organosilane compound serving as a lubricant and represented by the following general formula: ##STR1## where R is a saturated or unsaturated monovalent hydrocarbon residue having from 7 to 21 carbon atoms, n is 0, 1 or 2, and p is an integer from 1 to 12. The organosilane lubricant compound may be incorporated in the magnetic layer itself, in a back coating layer, or it may constitute a layer on the magnetic layer or on the back coating layer.

The magnetic recording medium contains the magnetic layer comprising the magnetic or magnetizable powders or particles and the binder comprising a composition containing

A magnetic recording medium having a magnetic layer which is cured by irradiating radiation onto the magnetic layer in which magnetic or magnetizable powder material surface-treated with a silicon compound having a silanol group and/or a silanol-forming group upon hydrolysis and a double-bond sensitive to radiation irradiated is present with a binder. The magnetic recording medium having the aforesaid structure has a sufficient durability.

A magnetic recording medium having a layer containing as a lubricant one or more organo-polysiloxane compounds having the following formula (I): ##STR1## (wherein R.sub.1 is a divalent hydrocarbon residue having 1 to 5 carbon atoms; R.sub.2 is a monovalent hydrocarbon residue having from 7 to 21 carbon atoms; R.sub.3 and R.sub.4 may be the same or different and are --CH.sub.3, --(CH.sub.2).sub.2 (CF.sub.2).sub.k CF.sub.3 or --R.sub.1 SCOR.sub.2 ; k is 0 or an integer ranging from 1 to 12; each of l, m and n is independently 0 or an integer ranging from 1 to 200 and the sum of 1+m+n is up to 300, with the proviso that when at least one of R.sub.3 and R.sub.4 is the group --R.sub.1 SCOR.sub.2, each of l, m and n may be 0 and that when at least one of R.sub.3 and R.sub.4 is a group other than the group --R.sub.1 SCOR.sub.2, each of l and m may be 0 but n is an integer ranging from 1 to 200).

The thermoplastic polyurethane resin having a molecular weight larger than about 5,000 is obtainable by the polyaddition of a long chain diol (A) having a molecular weight ranging from about 500 to 3,000, an organic diisocyanate (C) and a short chain triol (D) having a molecular weight lower than about 500 and specified structures and, as desired, a short chain diol (B) having a molecular weight ranging from about 50 to 500, in specified ratios. The thermoplastic polyurethane resin provides particularly enhanced heat resistance and solvent resistance with improved dispersibility of a pigment or the like and other resins and favorable compatibility with a solvent or the like.

Thermoplastic polyurethane resins

The magnetic recording media are constructed such that a lubricating layer containing an amine compound represented by the formula: ##STR1## (wherein R is a hydrocarbon residue having from 7 to 21 carbon atoms and n is an integer ranging from 1 to 10) is disposed on at least one surface of a non-magnetic substrate with a magnetic layer. The magnetic recording media have an improved lubricating characteristics with a low friction coefficient.

Magnetic recording medium with amino lubricating layer

The invention provides a novel diorganopolysiloxane compound composed of dimethysiloxane units, methyl (2-perfluoroalkylethyl)siloxane units and methyl acyloxyalkylsiloxane units. The novel diorganopolysiloxane compounds of the invention have excellent lubricating properties so that they are useful as an additive ingredient in various materials such as coating compositions, magnetic layer of recording tapes and the like where lubricity or mold releasability is essential.

Novel diorganopolysiloxane compounds

A magnetic recording medium having a layer containing as a lubricant one or more organo-polysiloxane compounds having the following formula (I): ##STR1## (wherein each of A.sub.1 and A.sub.2 is independently --CH.sub.3, --CH.sub.2 --CH.sub.2 --(CF.sub.2).sub.q --CF.sub.3 or --R.sub.1 OCOR.sub.2 ; R.sub.1 is a divalent hydrocarbon residue having 1 to 5 carbon atoms; R.sub.2 is a monovalent hydrocarbon residue having from 7 to 21 carbon atoms; each of l, m and n is independently O or an integer ranging from 1 to 200; and each of p and q is independently O or an integer ranging from 1 to 12; provided that when at least one of the groups A.sub.1 and A.sub.2 is the group --R.sub.1 OCOR.sub.2, each l, m and n may be O and that, when each group A.sub.1 and A.sub.2 is one of the groups other than the group --R.sub.1 OCOR.sub.2, each l and m may be O and n is an integer ranging from 1 to 200).

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Sendai, Japan

Masashi Somezawa