Hitachi Maxell, Limited

Jozo Shimizu

Satoru Yamaguchi

Haruo Andoh

Kozaburoh Satoh

Shigeo Aoyama

Osamu Saito

Hiroshi Zaitsu

Toshihiko Tanabe

Kozaburo Sato

A magnetic recording medium which comprises a first magnetic layer on a base and a second magnetic layer thereon, the first magnetic layer containing magnetic particles having an average particle length (long axis diameter) of 0.4 to 0.7 .mu., the second magnetic layer containing magnetic particles having an average particle length (long axis diameter) of 0.25 to 0.35 .mu., the coercive force of which being 370 to 460 oersteds, and the ratio of coercive force of the upper or second layer to that of the lower or first magnetic layer being 1.05/l to 1.5/l. The magnetic recording medium has excellent sensitivity and frequency characteristics at entire frequency bands with less noise.

Magnetic recording medium

A magnetic recording medium comprising a substrate and a magnetic layer coated thereon, the magnetic layer containing magnetic powder, a resinous binding agent and at least one sorbic acid compound selected from the group consisting of sorbic acid and derivatives and metal salts thereof, such that the magnetic powder is well dispersed in the magnetic layer and which has improved electrical properties.

A magnetic recording medium which comprises a first magnetic layer on a base and a second magnetic layer over the first magnetic layer, the second magnetic layer containing magnetic particles having an average particle length (long axis diameter) of not more than 0.35.mu. , with a coercive force of from 660 to 760 oersteds, and the ratio of the coercive force of the upper or second magnetic layer to that of the lower or first magnetic layer being 1.1/1 to 1.6/1. The resulting magnetic recording medium has excellent sensitivity and frequency characteristics over the entire frequency bands with less noise.

A magnetic recording medium improved in lubricity and abrasion resistance, which comprises a base material and a magnetic layer provided thereon, said magnetic layer comprising magnetic particles and a binder, characterized in that said magnetic layer further comprises at least one silicone compound of the formula: ##STR1## wherein X is the same or different and --A--COOH, --A--OH, ##STR2## or --A--NH.sub.2 in which A is a divalent hydrocarbon group having not more than 26 carbon atoms, Y and Y' are each --X or --CH.sub.3, p is an integer of 0 to 1,000 and q is an integer of 1 to 500 but p+q is not more than 1,000 in an amount of 0.1 to 5% by weight based on the weight of the magnetic particles in the magnetic layer.

Magnetic recording medium comprising a support or carrier sheet and a magnetic layer formed on one side of the support, wherein there is provided between the support and the magnetic layer at least one intermediate layer of resinous polymeric material including particles of carbon black having large specific surface area and high oil absorption so that electrification of the recording medium can be prevented with good adhesiveness of the magnetic layer to the support.

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Nagaokakyo, Japan

Jozo Shimizu