METHOD FOR SEALING STRETCHED POLYPROPYLENE FILM

摘要

PURPOSE:To make a stretched polypropylene film suitable for high speed sealing, by laminating the stretched polypropylene film having a specific composition by an adhesive based on a solvent. CONSTITUTION:Stretched films comprising a polypropylene resin composition containing 15-60wt% of a petroleum resin and/or a terpene resin are laminated by an adhesive based on a hydrocarbon solvent and/or a chlorine type solvent. In order to seal the films, the adhesive is applied to both opposed surfaces of two films or to the single surface of one of them and both films are bonded under pressure by nip rolls immediately after the adhesive is applied or after the adhesive is slightly subjected to preparatory drying in a range not losing the solvent to be laminated. In coating, a coating method by a bar coater or a method for dripping the adhesive from a fine tube can be used. The coating thickness of the adhesive is pref. set to 5mum or more as the liquid film thickness of a coating solution in order to obtain stable adhesive strength.