PURPOSE: To obtain the titled film having resistance to blocking, with the properties of matter and appearance of the film kept, by coating a surface of a film whose orientation and crystalization have not yet been completed with an aqueous dispersion containing polyester and an inorganic matter with a specified average particle diameter in specified quantities, orientating the film, and subjecting it to heat treatment.
CONSTITUTION: The surface of a polyester film (e.g. a polyethylene terephthalate film or the like) whose orientation and crystalization have not been yet completed is coated with an aqueous dispersion containing 100pts.wt. polyester resin A (e.g. a polyethylene terephthalate copolymerized with 5 Na-sulfoisophthalic acid, etc.) and 0.1W1,000pts.wt. inorganic matter B (e.g. silicon dioxide, etc.) having an average particle diameter 100μ or less, and by subjecting the film to orientation and heat treatment to complete the orientated crystalization, the intended film is obtained. It is desirable to add a nonionic surface active agent to the aqueous dispersion.