| 摘要 |
PURPOSE:To prevent the occurrence of shrinkage spot by a method in which terephthalic acid and ethylene glycol are used as main components, and the polyester film composed of two polyester resin with specified glass transition points is caused to have a specified heat shrinkage factor. CONSTITUTION:Polyester resin A contains terephthalic acid and ethylene glycol as its main components, and has 80 deg.C or lower glass transition point obtained by means of the measurement by using differential scanning calorimeter. Polyester resin B has 85 deg.C or higher glass transition point, and preferably contains at least 20mol.% or more fatty group of one kind or cycloaliphatic carboxylic acid and/or fatty group or cycloaliphatic diol. This composition has preferably e.g. polyester resin A of 20-98wt.% range and polyester resin B of 2-80wt.% range. The film obtained by using such polyer in extruding or calender process has 30% or more heat shrinkage factor at 100 deg.C and its stable heat shrinkage is shown. |
