Magnetic recording medium - comprising substrate with high Young's modulus, undercoat and ferromagnetic powder coat contg. binder, used esp. for durable tape

摘要

Magnetic recording medium has a nonmagnetic substrate (I) with an undercoat (II) and then a magnetic coat (III) of ferromagentic powder and binder (IV) on at least one side. The sum of the Young's modulus in the machine direction (MD) and transverse direction (TD) of (I) is 1400 kg/sq. cm or more than the adhesion between (I) and (III) is 90 g or more. Pref. (II) is produced from a polyester contg. a naphthalene ring and opt. also a polyurethane. (I) pref. consists of polyethylene naphthalate, polyimide or polyamide, esp. polyethylene-2,6-naphthalene, and the coating soln. for (III) contains at least 20 (wt.)% cyclohexanone (V) w.r.t. total solvent. (IV) includes resin(s) with functional sulphonic, phosphoric or phosphonic acid, epoxide or OH gp(s).. USE/ADVANTAGE - The medium is useful e.g. for magnetic tape. It is suitable for long-term recording and has excellent electromagnetic and running properties and excellent durability, with unvarying high output. Sepn. of powder at the edge during running and drop-outs are avoided