摘要 |
PURPOSE:To improve high heat-shrinkability and cracking resistance, by preparing the polymer formulation composed of the mixture of medium- or low- pressure linear low density PE (LLDPE) and ethylene-vinylacetate copolymer (EVA) or the mixture of LLDPE with the blend of EVA and high-pressure branched low density PE (BLDPE) as a tube material and making the degree of mechanical orientation before irradiation of accelerated electron beam less than 85% of shrinkability. CONSTITUTION:The polymer formulation containing 30-98pts.wt. of LLDPE as a primary component, 70-2pts.wt. of EVA or the blend of EVA and BLDPE as a secondary component and 0.1-5.0pts.wt. of an antioxidant is prepared as the tube material. Ethylene-ethyl acrylate copolymer (EEA) or the blend of EEA with BLDPE may be used as a secondary component. The sheet is formed by the polymer formulation, the degree of orientation of the sheet in the direction of the machine before irradiation of accelerated electron beam is made less than 85% of shrinkability and the degree of crosslinking is made more than 25% of the gel fraction at the state at which the heat-shrinkable tube is formed. |