| 摘要 |
<p>1,271,591. Magnetic compositions. MEMOREX CORP. 19 Feb., 1970 [20 Feb., 1969], No. 8017/70. Heading H1H. [Also in Division C3] A magnetic coating composition comprises magnetic particles dispersed in a binder comprising: (A) an epoxy resin containing reactive oxirane groups, mol. wt. 800-5000, epoxide equiv. wt. 400-2600; (B) an aliphatic fatty acid polyamide having an amine value of at least 300; (C) a mixture of a primary amine and a complex salt of a Lewis acid and a primary amine. The ratio of amine groups in the polyamide to oxirane groups in the epoxy resin is 0À8: 1 to 2 : 1, and the amount of mixture (C) is 0À1 to 2À0% by wt. based on the total binder composition including the magnetic particles. Ferric oxide and chromium dioxide particles are specified. The composition is applied to a tape, e.g. polyester, or to a rigid substrate e.g. aluminium or plastics, and heat-cured. In examples, compositions in which (C) is a mixture of N-aminoethyl piperazine or diethylene triamine with BF 3 -ethylamine complex are applied to polyester films and heat-cured at 135-150‹ C. for 3 mins. The magnetic recording media so produced do not require surface-finishing.</p> |
