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Magnetic recording medium
| Details |
Inventors: Ogawa, Hiroshi; Tamai, Yasuo;
Assignee: Fuji Photo Film Co.,Ltd. (Kanagawa, JP)
Primary Examiner:
Assistant Examiner:
Attorney, Agent or Firm:
A magnetic recording medium comprising a support having coated thereon a magnetic recording layer containing a ferromagnetic powder dispersed in a binder and a vinyl chloride-vinyl acetate copolymer having a degree of polymerization from about 10 to 100 and at least one terminal carboxyl group. The magnetic recording medium contains the above copolymer in an amount of from about 0.1 to 10 wt % based on the amount of ferromagnetic powder, and preferably also contains a conventional binder. This magnetic recording medium provides both video and audio magnetic tapes having superior running properties, durability and electromagnetic properties. |
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DETAILED DESCRIPTION OF THE INVENTION The copolymer used in the present invention can be obtained by a conventional radical polymerization and ionic polymerization, using polymerization initiators shown in the following table.
______________________________________
Chemical Abbre-
Structure Structure viation
______________________________________
4,4'-Azo-bis(4- cyanopentanoic acid)
##STR1## (ABCPA)
Succinic Acid Peroxide
##STR2## (SAP)
Glutaric Acid Peroxide
##STR3## (GAP)
2,2'-Azo-bis(4- carboxy-2-methyl butyronitrile)
##STR4## (ABCMN)
______________________________________
The degree of polymerization of the copolymer of the present invention should not be less than about 10 because adjustment of copolymerization ratio and polymerization degree is difficult, and should not be more than about 100 because dispersibility of ferromagnetic powder is not improved.
The degree of polymerization of the copolymer used in the present invention is preferably about 20 to 80.
The distribution of molecular weight (MW/MN) of the copolymer is about 1 to 5, preferably about 1 to 3.
In addition to vinyl chloride and vinyl acetate, as components of the copolymer, maleic anhydride and vinyl alcohol which is obtained by hydrolysis of vinyl acetate after a copolymerizing reaction can be included.
The weight ratio of the components in the copolymer can be varied and preferably is about 60 to 95% of vinyl chloride, about 0.
5 to 20% of finyl acetate, about 0 to 5% of maleic anhydride and about 0 to 15% of vinyl alcohol.
p In addition to the above components, a polymerization initiator and/or a chain transferring agent can be included therein.
The amount of the copolymer contained in the magnetic layer is about 0.
1 to 10 wt %, preferably about 1 to 5 wt % based on the amount of ferromagnetic powder.
It is preferred that the copolymer of the present invention is used in combination with a conventional binder and if desired, conventional additives for a magnetic layer
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