MANUFACTURE OF OLEFIN SERIES SHRINK FILM

摘要

PURPOSE:To obtain an olefin series shrink film which is superior in heat- resisting properties, by a method wherein a sheet is molded of a composite having a specific ethylene-propylene copolymer and a propylene monopolymer for its ingredients whose composition has been limited, the sheet is preheated at a limited temperature and the same is stretched unidirectionally while a surface temperature difference of both the sides of the same is being kept at a specific temperature. CONSTITUTION:A sheet is molded out of a composite composed of a 100wt part ethylene-propylene copolymer whose ethylene content is 2-10wt% and melt flow index is 0.5-10g/10min and a 0-50wt part propylene monopolymer whose melt flow index is 0.5-10g/10min. The sheet is stretched unidirectionally by preheating the same at the temperature of 100-140 deg.C and getting a surface temperature difference of more than 2 deg.C between both the surfaces for the same. It matters little to the titled method to add a coloring agent, antistatic agent and anti-oxidizing agent. Stretching treatment to obtain heat-shrinkable film is a device to stretch at least in a unidirection out of a longitudinal and lateral directions and desirably it is stretched in the longitudinal direction.