Title:
PRODUCTION METHOD FOR BIAXIALLY-ORIENTED POLYPROPYLENE FILM
Document Type and Number:
WIPO Patent Application WO/2021/193507
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a biaxially-oriented polypropylene film which has high rigidity, has excellent heat resistance at temperatures as high as 150°C, easily maintains a bag shape when formed into a packaging bag, and has few wrinkles in a sealed part when heat sealed. Provided is a production method for a biaxially-oriented polypropylene film, said production method comprising, in the given order: a step in which a polypropylene resin composition containing a polypropylene resin with a meso pentad fraction of at least 97.0% is extruded to obtain an unstretched sheet; a step in which the unstretched sheet is stretched in the length direction thereof; a preheating step in which the length-direction stretched film is heated to a preheat temperature in the range from Tm to Tm+25°C; a step in which the preheated length-direction stretched film is stretched in the width direction by a factor of at least 10 at a temperature in the range from Tm-10°C to the preheat temperature; a step in which the film is cooled at a temperature that is not greater than the width-direction stretching temperature when the width-direction stretching was completed and is in the range from Tm-80˚C to Tm-15˚C; and a heat treatment step.
Inventors:
IMAI TORU (JP)
YAMADA KOUJI (JP)
HORINOUCHI KAZUHITO (JP)
NAKANO MAHIRO (JP)
YAMADA KOUJI (JP)
HORINOUCHI KAZUHITO (JP)
NAKANO MAHIRO (JP)
Application Number:
PCT/JP2021/011659
Publication Date:
September 30, 2021
Filing Date:
March 22, 2021
Export Citation:
Assignee:
TOYO BOSEKI (JP)
International Classes:
B29C55/14; C08J5/18
Domestic Patent References:
| WO2017159103A1 | 2017-09-21 | |||
| WO2014024969A1 | 2014-02-13 | |||
| WO2015072291A1 | 2015-05-21 |
Foreign References:
| JP2018141122A | 2018-09-13 |
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