| 摘要 |
<p>1,039,648. Magnetic structures. GENERAL ELECTRIC CO. Feb. 16, 1965 [March 20, 1964], No. 6697/65. Heading H1H. [Also in Division B5] A laminated magnetic recording tape comprises a polycarbonate supporting lamina which is in direct contact with a magnetic lamina comprising magnetic particles in polycarbonate binder. Suitable polycarbonate resins are aliphatic, aromatic or heterocyclic compounds and may include plasticizers, stabilizers, fillers, curing agents, dyes and pigments. Suitable solvents are alkyl halides, e.g. methylene chloride and ethylene chloride. Suitable magnetic materials are iron, metal alloys, #Fe 2 O 3 and Fe 3 O 4 . The magnetic lamina is prepared by forming a dispersion of the magnetic particles in a solution of the carbonate binder in a solids/solvent ratio of 20: 80 by weight. This dispersion is applied by doctor blade to a temporary support having a smooth surface, e.g. a belt of polyethylene terephthalate, stainless steel or aluminium. The magnetic material is oriented and dried by air, oven, blower, or radiant heater to give a layer 0À0004 inch thick. The supporting lamina may be based on a glass fabric reinforcement which may be woven or unwoven and of which details are given. If this fabric has a starch oil sizing this latter may be removed by heating. Thereafter the fabric is optionally subjected to a priming coating of an elastomer such as ethylene propylene rubber, polyisobutylene, polycarbonate elastomer, silicone fluid, polyethylene-vinyl acetate copolymer and nitrile silicone. The fabric is then impregnated with the polycarbonate which has a M.W. between 15,000 and 20,000, using knife edges to control thickness. The fabric is dried either wholly in a vacuum, or partly in air followed by heating in an oven at 130‹ C. for 1 hour. The dried tape is then subjected to a heat-pressure treatment-for example by calendering-to give smooth even surfaces. Alternatively these surfaces are formed by laminating polycarbonate films on either side of the glassreinforced tape. Continuous processes may be utilized. The supporting lamina is united with the magnetic lamina by heat and pressure and a uniform surface is provided. A further supported lamina containing silica as filler instead of magnetic particles may be applied tothe base layer on the opposite side from the magnetic layer. In this case the base layer need not be glass-reinforced.</p> |
