| 摘要 |
PURPOSE:To obtain the titled film which has no bubbles and is useful as a substrate for photographic paper, labels, display board, white board, X-ray intensifying screen, etc., by melt-extruding a mixture of polyethylene terephthalate, pulverized calcium carbonate and a phosphorus compd. and biaxially orienting the film. CONSTITUTION:100pts.wt. polyethylene terephthalate (A) composed of at least 80mol% of ethylene terephthalate units, 5-25pts.wt. pulverized calcium carbon ate (B) having an average particle size of 0.1-4mu, a degree of whiteness of not lower than 80% and an impurity content of not higher than 10%, and 0.005-1pt.wt. phosphorus compd. (C) such as phosphorous acid, phosphoric acid and allyl or alkyl phosphates, etc. are thoroughly dried and then mixed with one another in a mixer, etc. to obtain a mixture. The mixture is fed to an extruder heated to 260-290 deg.C and melt-extruded through a T-die. The resulting unoriented film is simultaneously oriented in the lengthwise and widthwise directions 2-5 times at a drawing temp. of 80-130 deg.C. If desired, the oriented film is thermally set at 150-235 deg.C for 1-60sec to obtain the titled film. |
