| 摘要 |
<p>A coating compsn. for applying a transparent magnetic recording layer to a support is claimed. It comprises a polymeric binder, ferromagnetic particles and a dispersing medium for the polymeric binder. The dispersing medium comprises: (a) a cpd. of formula R"C(O)-C(R')H-C(O)-OR (I), where R = 1-8C alkyl, phenyl or benzyl, R' = H or (m)ethyl, and R" = 1-5C alkyl; and (b) methylene chloride and/or lower alkyl ketones. The lower alkyl ketone is acetone. The cpd. of formula (I) is present in amt. 0.5-10 (2-8,4-6) wt.%, based on the total wt. of the dispersing medium. Methylene chloride is present in amt. 5-95 (15-80) wt.%, the lower alkyl ketone is present in amt. 2-90 (15-80) wt.% and the cpd. of formula (I) is present in amt. 0.5-10 (2-8)wt.%. Abrasive particles having an av. dia. of 0.04-0.4 ~mm and a Mohs hardness of at least 6 are present in the coating compsn.. An effective amt. of a surfactant to prevent agglomeration of the magnetic particles is included in the coating compsn. (I) is methyl acetoacetate. The polymeric binder is a cellulose ester (pref. cellulose diacetate), a polyurethane or a vinyl polymer. The compsn. includes a crosslinking agent which is aziridine, melamine or pref. an isocyanate.</p> |
