The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 23, 1991
Filed:
Apr. 21, 1988
Takahito Miyoshi, Kanagawa, JP;
Hiroo Inaba, Kanagawa, JP;
Kazuko Hanai, Kanagawa, JP;
Yasuyuki Yamada, Kanagawa, JP;
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Abstract
An improved magnetic recording medium comprises a nonmagnetic support and a magnetic recording layer which comprises a ferromagnetic powder, a lubricant and an abrasive dispersed in a binder comprising a specific polyurethane resin and a specific vinyl chloride copolymer at a ratio (polyurethane resin:vinyl chloride copolymer) in the range of 15:85 to 90:10. The polyurethane resin has a polar group such as --COOM, --SO.sub.3 M, --OSO.sub.3 M and --PO(OM').sub.2, wherein M is hydrogen or an alkali metal atom, and M' is hydrogen, an alkali metal atom or a lower hydrocarbon group, one polar group being contained per 53,000 to 100,000 of the number-average molecular weight of the resin, and the vinyl chloride copolymer has one of the above-mentioned polar group, one polar group unit being contained per 10,000 to 100,000 of the number-average molecular weight of the copolymer. The recording layer contains a fatty acid ester lubricant having a low melting point, a carbon black having an average particle size of 90-150 .mu.m, and/or a .alpha.-alumina having a small average particle size.