| 摘要 |
PURPOSE:To prepare the title film excellent in the flatness, slip properties, wear resistance, etc., by forming a polyester contg. a specified amt. of crosslinked polymer particles, specified in the mean particle diameter, the particle diameter ratio, etc., into a film and orienting the film in such a way that the degree of deformation of the crosslinked polymer particles falls within a specified range. CONSTITUTION:Crosslinked polymer particles (e.g. an ethylene glycol dimethacrylate-n-butyl acrylate-divinylbenzene copolymer particles) having a mean particle diameter of 0.1-1.5mum and a particle diameter ratio of 1-1.1 is prepd. The particles are added in the process for producing a polyester to produce the polyester contg. 0.001-4wt.% particles. The produced polyester is formed into a film, which is oriented in such an way that the degree of deformation of the particles due to the orientation is 1.2-5, thus giving a biaxially oriented polyester film. The resulting film is suitable for the use as a base film of a magnetic recording medium. |
