Magnetic recording medium
First Claim
1. A magnetic recording medium comprising a non-magnetic support and a magnetic recording layer provided on the support, said magnetic recording layer comprising a binder and a ferromagnetic powder dispersed therein, which is characterized in that:
- said magnetic recording layer comprises a fatty acid ester lubricant and a lubricant other than the fatty acid ester lubricant;
said binder is composed of a resin component comprising a vinyl chloride copolymer resin containing a repeating unit which has a polar group and having a glass transition point of not lower than 50°
C. and a polyurethane resin containing a repeating unit which has a polar group and having a glass transition point of lower than 50°
C., a ratio by weight of said vinyl chloride copolymer resin to said polyurethane resin being in the range of 70/30 to 30/70; and
at least one resin of said resins contains a repeating unit having at least one polar group selected from the group consisting of --SO3 M, --OSO3 M and --PO(OM'"'"')2, wherein M is hydrogen or an alkali metal atom, and M'"'"' is hydrogen, an alkali metal atom or a lower hydrocarbon group.
1 Assignment
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Accused Products
Abstract
In a magnetic recording medium such as a video tape comprising a nonmagnetic support and a magnetic recording layer provided on the support, said magnetic recording layer comprising a binder and a ferromagnetic powder dispersed therein, the improvement in which:
the magnetic recording layer comprises a fatty acid ester lubricant and a lubricant other than the fatty acid ester lubricant;
the binder is composed of a resin component comprising a resin containing a repeating unit which has a polar group and having a glass transition point of not lower than 50° C., and a resin containing a repeating unit which has a polar group and having a glass transition point of lower than 50° C; and
at least one resin of the resins contains a repeating unit having a polar group such as --SO3 M, --OSO3 M or --PO(OM'"'"')2, wherein M is hydrogen or an alkali metal atom, and M'"'"' is hydrogen, an alkali metal atom or a lower hydrocarbon group.
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Citations
7 Claims
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1. A magnetic recording medium comprising a non-magnetic support and a magnetic recording layer provided on the support, said magnetic recording layer comprising a binder and a ferromagnetic powder dispersed therein, which is characterized in that:
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said magnetic recording layer comprises a fatty acid ester lubricant and a lubricant other than the fatty acid ester lubricant; said binder is composed of a resin component comprising a vinyl chloride copolymer resin containing a repeating unit which has a polar group and having a glass transition point of not lower than 50°
C. and a polyurethane resin containing a repeating unit which has a polar group and having a glass transition point of lower than 50°
C., a ratio by weight of said vinyl chloride copolymer resin to said polyurethane resin being in the range of 70/30 to 30/70; andat least one resin of said resins contains a repeating unit having at least one polar group selected from the group consisting of --SO3 M, --OSO3 M and --PO(OM'"'"')2, wherein M is hydrogen or an alkali metal atom, and M'"'"' is hydrogen, an alkali metal atom or a lower hydrocarbon group. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification