| 摘要 |
1464414 Polytetramethylene 2,6-naphthalate TEIJIN Ltd 11 June 1974 [13 June 1973 29 Aug 1973] 25869/74 Heading B5B [Also in Division C3] Films of polytetramethylene 2,6-naphthalate having a density not in excess of 1À318 and being unstretched are produced by extruding the polymer into a film and cooling at from 75‹ C. to room temperature rapidly so as to produce a density not in excess of 1À318. The polyester preferably has a reduced viscosity of at least 0À70 and a light transmittance, or a 150 micron thick film of at least 20%. The polyester may contain up to 10 mol per cent of other polyesters. |
