PURPOSE: To obtain the titled film capable of giving floppy disks hardly causing drop out, by melting polyethylene terephthalate containing specific fine particles, filtering the melt under specific condition, molding the filtered melt into the form of a sheet, cooling and solidifying the sheet and biaxially drawing the resultant sheet.
CONSTITUTION: Polyethylene terephthalate (preferably consisting of ≥95mol% ethylene terephthalate) containing 0.05W2wt%, preferably 0.2W0.8wt% rutile type titanium dioxide particles, preferably subjected to surface treatment with aluminum oxide, etc., having 0.1W1.0μm, preferably 0.25W0.70μm average particle diameter is melted while heating preferably at 280W290°C, filtered under 120W200kg/cm2, preferably 140W180kg/cm2 pressure difference between parts before and after a filter, molded into the form of a sheet, which is then cooled, solidified and biaxially drawn (preferably at 80W130°C at 2.8W4.0 times in each direction) to afford the aimed film.
| JPH1052851 | FLOW PATH FOR FILTERING MOLTEN RESIN |
| JPH04351524 | BREAKER PLATE FOR EXTRUSION MOLDING |
| WO/1996/002380 | SCREEN CHANGER PROVIDED WITH GEAR PUMP FOR PLASTIC EXTRUSION MOLDING |
UEDA TOMOAKI
ITO KIYOHIKO
