| 摘要 |
PURPOSE:To provide a polyester film small in a void content, excellent in slipperiness, chipping resistance, etc. and suitable for a magnetic tape or the like, by incorporating inert cornual particles having a plurality of hornlike projections on the powder surface in a polyester film. CONSTITUTION:Inert cornual particles having a plurality of hornlike projections on their surface (e.g., silica or titanium dioxide) are added to a polyester film (e.g., polyethylene terephthalate film). The ratio H/D (wherein H is the height of the projection and D is the diameter of an inert particle) is suitably 0.05-0.3, and the content of the inert particles is suitably 0.005-5wt.%. An example of a process for producing said cornual particles comprises forming silica particles having a specified particle diameter and a flat surface and comprising an aggregate of microparticles of about 1-10mmu by, for example, sodium silicate dealkalification process and growing microparticles on the surfaces. |
