| abstract |
PURPOSE:To obtain the title film excellent in lubricity, chipping resistance and scratch resistance, etc., by adding spherical silica particles of specified properties and metal terephthalate particles of specified properties as lubricants to a polyester, forming this mixture into a film and biaxially stretching this film. CONSTITUTION:0.005-3wt.% spherical silica particles of an average particle diameter of 0.05-4mum and a particle diameter ratio (major diameter/minor diameter) of 1-1.2 and 0.005-3wt.% particles of a metal terephthalate or a metal salt containing an alkylene terephthalate component (e.g., calcium terephthalate) of an average particle diameter of 0.05-5mum are added as lubricants to a polyester (e.g., polyethylene terephthalate). This polyester is formed into a film, which is biaxially stretched to obtain the title biaxially oriented polyester film. This film is small in a void size, uniform in the irregularities on the film surface, so that is can be suitably used as a video film, etc. |