Magnetic recording medium
AssigneeFujitsu Limited
InventorsKazuo Ogasa, Seiya Ogawa
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Abstract
A magnetic recording medium having finely divided magnetic metal oxide particles dispersed in a thermosetting resin binder and a thickness of no greater than 5 microns is provided. The thermosetting resin binder comprises: (a) 30 to 95 wt.% of a copolymer of 25 to 65 wt.% of alkyl acrylate or alkyl methacrylate, 3 to 30 wt.% of N-methylolacrylamide or N-alkoxymethylacrylamide and 10 to 60 wt.% of styrene or a methyl styrene, (b) 5 to 70 wt.% of an epoxy resin predominantly comprised of a condensation product of bisphenol A and epihalohydrin, and; (c) 0 to 50 wt.% of phenolic resin or amino resin. The magnetic recording medium is superior in abrasion resistance, solvent resistance and dispersion of the magnetic material therein, and possesses improved recording density.
Claims9
A magnetic recording medium comprising finely divided magnetic metal oxide particles dispersed in a thermosetting resin binder composition and in the form of a thin layer film having a thickness of less than 5 microns closely adhered to a non-magnetic substrate, said thermosetting resin binder composition comprising:
- a. 30% to 95% by weight of a copolymer consisting essentially, based on the weight of the copolymer, of
- 1. 25% to 65% by weight of units derived from at least one compound selected from the group consisting of alkyl acrylate and alkyl methacrylate, the alkyl group having 1 to 4 carbon atoms,
- 2. 3% to 30% by weight of units derived from at least one compound selected from the group consisting of N-methylolacrylamide and N-alkoxymethylacrylamide, the alkoxy group having 1 to 4 carbon atoms,
- 3. 10% to 60% by weight of units derived from at least one compound selected from styrene and methyl styrenes, and,
- 4. 0% to 30% by weight of units derived from at least one other copolymerizable ethylenically unsaturated compound, and;
- b. 5% to 70% by weight of an epoxy resin, the predominant constituent being a condensation product of bisphenol A and epihalohydrin, possessing an average molecular weight of approximately 300 to approximately 2,000.
Dependencies are inferred from the claim text.