WHITE POLYESTER FILM FOR MAGNETIC RECORDING CARD

摘要

PROBLEM TO BE SOLVED: To meet the requisites for a magnetic recording card and the film making properties and processability of a white polyester film as the base of the magnetic recording card. SOLUTION: A film contains 5-10 wt.% of titanium dioxide. In the relationship between the dimensional variation in the width direction and temperature of the film, the shrinkage starting temperature is 180-20 deg.C, and the shrinkage rate at the temperature is 0-5%. The number of projections 150μmϕor above in size and 30μm or above in height on the surface of the film is 1 pc/m<2> or below.