| 摘要 |
<p>1414847 Polyurethane compositions RCA CORPORATION 30 April 1973 [1 May 1972] 20569/73 Heading C3R A coating composition slurry for a magnetic recording element comprises a finely-divided magnetic material and an isocyanate-terminated polyurethane prepolymer blocked with benzophenone oxime or a ring-substituted benzophenone oxime, a coreactant comprising a polyfunctional active hydrogen bearing, organic compound, and an organic solvent, and optionally a vinyl copolymer. The magnetic material is preferably acicular 8Fe 2 O 3 . In an example an aminourethane prepolymer is first prepared by reacting toluene 2,4 diisocyanate in trichloroethane (TCE) with the polymer prepared by -passing carbon dioxide through a mixture of #-caprolactone, N,N<SP>1</SP>-bis-(2-hydroxyethyl)piperazine and K 2 CO 3 followed by heating. The resulting polymer is then blocked with benzophenone oxime. A magnetic coating composition is then prepared comprising the blocked prepolymer in TCE, 8Fe 2 O 3 , a bis-2-aminopropyl ether of a diol as coreactant,α,α<SP>1</SP>-dichlorop-xylene, and stannous laurate, which is coated on to oriented polyester film and cured. Other magnetic coating compositions are prepared from the above blocked aminourethane prepolymer, 8Fe 2 O 3 , TCE and any one of the following coreactants: 1,6-hexane-diamine, polyoxypropylene - triamine, 3,31 - dichloro - 4,4<SP>1</SP> diaminodiphenyl-methane and 1,6-hexanediol. In a further example coating compositions are prepared from the isocyanate terminated polyurethane prepolymer, ADIPRENE, (Registrated Trade Mark) blocked with benzophenone oxime, an hydroxyl substituted vinyl copolymer, trimethylolpropane as coreactant, lithium stearate as lubricant, carbon black, 8Fe 2 O 3 , methylethylketone/xylene as solvent, and optionally 3,3<SP>1</SP>-dichloro-4,4<SP>1</SP>-diaminodiphenylmethane.</p> |
