| 摘要 |
PURPOSE:To provide a manufacturing process of a polyethylene biaxially oriented film having resin consisting mainly of linear low-density polyethylene for its raw materials and low-shrinkage properties. CONSTITUTION:Raw material resin consisting mainly of linear low-density polyethylene is cooled for solidification while melting and extruding the same, which is made into an unoriented sheet substantially, then after the sheet is oriented longitudinally and laterally respectively at least four times and less than seven times at an orientation temperature satisfying conditions of the following numerical formula number 1 and furthermore, the film is heat-treated at a temperature satisfying conditions of the following numerical formula number 2 and a polyethylene biaxially oriented film having thermal shrinkage factors not exceeding respectively 8% in a longitudinal and laternal directions is manufactured. (The number 1) Tm-30 deg.C<=T1<=Tm-10 deg.C (The number 2) Tm-15 deg.C<=T2<=Tm (In the above-mentioned formulas, the Tm, T1 and T2 show respectively the melting point of the raw material resin, the orientation temperature and a heat-treatment temperature). |
