PURPOSE: To obtain a magnetic recording medium which withstands severe environment by coating a magnetic layer contg. fine acicular ferromagnetic metallic powder on the film surface of biaxially oriented polyethylene 2, 6 naphthalene dicarboxylate (PEN) and maintaining ≤0.03% shrinkage difference over the entire circumference under prescribed resting conditions.
CONSTITUTION: The surface roughness of the PEN film is made 0.02μm and the magnetic recording medium is formed by mixing a cicular iron powder having 0.1W0.3μm length with a vinyl chloride/vinyl acetate copolymer and coating the mixture composed thereof on the film. the shrinkage of the film is required to be ≤0.03% in the entire circumferential direction after resting for 2hr in a 60°C 80% RH atmosphere. The disk warps and does not make uniform contact with a head if the shrinkage exceeds 0.03%. The biaxially oriented PEN film which has ≤4×10-6/°C difference in the coefft. of expansion by temp. over the entire circumferential direction is preferred and the tracks deviate from the head if the difference in the coefft. of expansion exceeds said value. The use of the PEN film having 13W25×10-6/°C coefft. of expansion is advantageous.
| JPS57158032 | MAGNETIC RECORDING MEDIUM |
| JP2007141304 | MAGNETIC RECORDING MEDIUM |
| JPS5916134 | MAGNETIC RECORDING BODY |
TOMITA HIROSHI
MASUDA SHIGEYOSHI
KOBAYASHI JUNJI
NAKAMURA SATOYUKI
