METHOD FOR MANUFACTURING BIAXIALLY ORIENTED POLYPROPYLENE FILM

WIPO Patent Application WO/2020/137795

A1

Provided is a biaxially oriented polypropylene film which has high rigidity, has excellent heat resistance even at the high temperature of 150˚C, can easily retain a bag shape when used as a packaging bag, and exhibits few wrinkles in seal parts when heat sealing has been performed thereon.　Also provided is a method for manufacturing the biaxially oriented polypropylene film comprising, in the following order: a step in which an unstretched sheet is obtained by extruding a polypropylene resin composition containing a polypropylene resin with a meso pentad fraction of at least 97.0%; a step in which the unstretched sheet is stretched in the length direction thereof; a preheating step in which the length-direction stretched sheet is heated to a preheating temperature of at least Tm and not higher than Tm+25˚C; a step in which the preheated length-direction stretched sheet is stretched in the width direction at a temperature of at least Tm-10˚C and not higher than the preheating temperature; a step in which the sheet is stretched in the width direction at a temperature of at least Tm-70˚C and not higher than Tm-5˚C, and lower than the temperature of the step in which the sheet is stretched in the width direction at a temperature of at least Tm-10˚C and not higher than the preheating temperature; and a heat treatment step.

YAMADA KOUJI (JP)
HORINOUCHI KAZUHITO (JP)
NAKONO MAHIRO (JP)
IMAI TORU (JP)

PCT/JP2019/049812

July 02, 2020

December 19, 2019

Click for automatic bibliography generation  

TOYO BOSEKI (JP)

B29C55/14; C08J5/18; B29K23/00; B29L7/00

WO2014104089A1

2014-07-03

JP2017500226A	2017-01-05
JP2018130958A	2018-08-23
JP2016188361A	2016-11-04
JP2006117956A	2006-05-11

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