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US 5,178,935 AGranted
Magnetic recording medium
AssigneeFuji Photo Film Co., Ltd.
InventorsShinji Saito, Hiroshi Ogawa, Naoyoshi Chino, Hiroo Inaba, Kazuaki Taga
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AssigneeFuji Photo Film Co., Ltd.
InventorsShinji Saito, Hiroshi Ogawa, Naoyoshi Chino, Hiroo Inaba, Kazuaki Taga
Estimating the term…
A magnetic recording comprising a non-magnetic support having thereon first and second magnetic layers containing a binder and a ferromagnetic powder. In a first embodiment, the content of the binder in each magnetic layer containing a vinyl chloride resin or a cellulose resin is characterized in relation to the quantity of the ferromagnetic powder contained therein. In a second embodiment, each of the magnetic layers is characterized in terms of a difference in glass transition point of a polyurethane resin contained therein. In a third embodiment, each of the magnetic layers is characterized in terms of thickness and polyisocyanate content, wherein the content of the polyisocyanate in the first magnetic layer is at least one part by weight larger than the amount of the polyisocyanate in the second magnetic layer.
A magnetic recording medium comprising a non-magnetic support having thereon a first magnetic layer and a second magnetic layer in this order, wherein said second magnetic layer is coated on said first magnetic layer while said first magnetic layer is in a wet condition, wherein said first magnetic layer and said second magnetic layer contain a vinyl chloride resin or a cellulose resin as a part of the binder;
A magnetic recording medium comprising a non-magnetic support having thereon double magnetic layers each containing a ferromagnetic powder dispersed in a binder, wherein the lower magnetic layer contains at least one kind of polyurethane resin having a glass transition temperature of from -50.degree. C. to -10.degree. C. as the binder, the upper magnetic layer contains at least one kind of polyurethane resin having a glass transition temperature of from -20.degree. C. to 40.degree. C. as the binder, the difference in the glass transition temperature between the polyurethane resin for the upper layer and the polyurethane resin for the lower layer is at least 10.degree. C., the amount of polyurethane resin is from 5% to 70% by weight of the entire binder composition of each layer, and the coercive force of the ferromagnetic powder for the upper magnetic layer is from 350 to 2,500 Oe.
Dependencies are inferred from the claim text.