Process for the preparation of polyester base film for magnetic recording media
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United States of America Patent
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Feb 17, 1998
Grant Date -
N/A
app pub date -
Jun 12, 1996
filing date -
Jun 14, 1995
priority date (Note) -
Expired
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Abstract
A polyester base film for magnetic recording media having improved adhesion to the magnetic layer applied thereon as well as good abrasion and scratch resistance prepared by melt-extruding a polyester resin containing inorganic and organic particles to form a sheet; extending the sheet; and heat-setting the extended film, wherein the heat-setting step is carried out by heat-treating a first surface of the film, which is to be coated with a magnetic material, at a temperature ranging from 170.degree. to 290.degree. C. for 1 to 50 seconds so that the crystallinity thereof ranges from 50 to 70% and heat-treating the other surface of the film at a temperatue which is lower than the first heat-treatment temperature by 20.degree. C. or more for 1 to 200 seconds so that the other surface attains a crystallinity which is lower than that of the first surface by at least 5%.
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