Coating compositions for a transparent magnetic recording layer

• Main Author: WEXLER, RONALD MYRON
• Format: Patent
• Language: English; French; German
• Published: 28.06.1995
• Edition: 6
• Subjects: ADHESIVES; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AUXILIARY PROCESSES IN PHOTOGRAPHY; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; CINEMATOGRAPHY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COMPOSITIONS BASED THEREON; CORRECTING FLUIDS; DYES; ELECTROGRAPHY; FILLING PASTES; GENERAL PROCESSES OF COMPOUNDING; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; HOLOGRAPHY; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INKS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; ORGANIC MACROMOLECULAR COMPOUNDS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR,STEREO-PHOTOGRAPHIC PROCESSES; PHOTOGRAPHY; PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHYSICS; POLISHES; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; THEIR PREPARATION OR CHEMICAL WORKING-UP; USE OF MATERIALS THEREFOR; WOODSTAINS; WORKING-UP

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 mu m 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.