| 摘要 |
PURPOSE:To obtain the title film excellent in hot dimensional stability and surface bondability and useful for, e.g., magnetic recording, by heat-treating a polyester film subjected to corona discharge treatment in a CO2-containing gas and wound in the form of a roll in hot air at a specified temperature. CONSTITUTION:A polyester film of a surface roughness >=30mum is obtained by biaxially stretching a polyester (e.g., polyethylene terephthalate) which has an intrinsic viscosity (as measured in o-chlorophenol) of 0.50-1.2 and a crystallinity of 40-70% and is a polymeric compound having ester bonds in the main chain and obtained by polycondensing a dicarboxylic acid with a diol. The surfaces of the film are subjected to corona discharge treatment in a mixed gas containing at least 0.5vol.% CO2, and the treated film is wound in the form of a roll by using a surface pressure of a touch roll of 20-150kg/m<2> to obtain a roll of the polyester film. This roll is heat-treated for 8-72hr in hot air at 30-65 deg.C, preferably, 40-50 deg.C, preferably, in an atmosphere containing at least 0.5vol.% CO2 and having a humidity of 50%.
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