| 摘要 |
PURPOSE:To obtain the titled film having a specific whiteness of raw polymer chip and a specific void ratio of the film, by melting and extruding polymer chips produced by adding a specific amount of fine calcium carbonate powder to polyethylene terephthalate and biaxially drawing the produced film. CONSTITUTION:Polymer chips produced by adding 5-30wt.%, preferably 8-25wt.% calcium carbonate fine powder (preferably having an average particle diameter of 0.3-1.5mum) to a polyethylene terephthalate (preferably containing >=90mol% ethylene terephthalate unit) are extruded in molten state and biaxially drawn (at an areal draw ratio of 9-15) to obtain the objective film having high reflectivity of light and excellent whiteness and satisfying the formulas alpha>=45 (preferably alpha>=50), 7<=beta<=30 (preferably 10<=beta<=25) and alpha.logbeta>=65, where in alpha (%) is whiteness of the chip and beta (%) is void ratio of the film. |
