| 摘要 |
PURPOSE:To contrive to improve the thickness accuracy and low temperature shrink characteristics by a method wherein crosslinkable polyethylene-based resin is stretched by the specified actual draw ratio so as to realize the specified gelling percentage and heat shrinkage factor of a film. CONSTITUTION:Crosslinkable polyethylene-based resin is stretched laterally by the actual draw ratio of 400% or more and longitudinally by the actual draw ratio of 200% or less under the low temperature such as longitudinal stretching temperature of from 70 deg.C to the melting point of the resin, and lateral stretching temperature of from 80 deg.C to the melting point of the resin. Further, a film, the gelling percentage of which is 20-70wt.%, the heat shrinkage factor at 110 deg. of which is 10% or more in the longitudinal direction and 50% or more in the lateral direction, and the clamping force of which under shrinking state is as large as the low temperature heat shrinkage stress in the lateral direction of 10kg/cm<2> or higher at 80 deg.C, is empolyed. As the polyethylene-based resin stock, one or mixture of low density polyethylene resins, the density of which is 0.905-0.935g/cm<3> at 23 deg.C and the melt index of which is 0.1-5g/10min at 190 deg.C, is used. Said resin is formed by extruder or the like in the shape of a sheet with a certain width and, after that, crosslinked by electron irradiation. |
