| 摘要 |
<p>1,248,504. Polyvinyl acetal/aziridine polymers. EASTMAN KODAK CO. 16 Jan., 1969 [19 Jan., 1968], No. 2524/69. Headings C3P and C3R. [Also in Division H1] A coating composition for a magnetic recording element comprises magnetic particles dispersed in a binder comprising the reaction product of a polyvinyl acetal and an aziridineterminated polymer which has a mol. wt. of at least 1000 and which is a poly(alklyene-ether) glycol or a linear dihydroxy-terminated polyester in which the terminal active hydrogen atoms have been replaced by a radical containing an aziridine ring, e.g. of formula The aziridine-terminated polymer may be made by reacting the above polyglycols or polyesters with an organic diisocyanate and then with an alkylenimine; and is belived to react with the hydroxyl groups of the acetal, e.g. polyvinyl butyral. The magnetic particles may be of acicular gamma iron oxide and the coating composition may contain a solvent, e.g. glycol monoacetate and methyl isobutyl ketone. The coating is cured by heating.</p> |
