BIAXIAL DRAWING PROCESS FOR POLYMER SHEET OR POLYAMIDES SHEET

摘要

PURPOSE:To provide the captioned sheet having uniform thickness and superior transparency by cooling down a sheet extruded on a moving cooled surface and by appling a corona discharge between the sheet and electrode. Successive drawing to the direction biaxial produces the sheet. CONSTITUTION:A polyamide thermoplastic polymerization having film forming property is extruded from the die 1 to moving cooled surface 3 as melting sheet material 2. After cooled down and solidified, the sheet is taken off from the cooling drum 3 by a take-off roll 4. The melting sheet material receives a streamer corona discharge 8 from the electrode 7 that has high voltage due to direct current high voltage power source 6. The sheet 5 taken off from the cooling drum 3 is drawn to MD direction by a roll longitudinal drawing machine and laternally by a tenter 10. Then a thermosetting treatment is effected and a film winder 11 winds up the completed film. EFFECT:By a discharge a crystallization is inhibitted and a transparency is improved.