Title:
BIAXIALLY ORIENTED POLYESTER FILM AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2021/125236
Kind Code:
A1
Abstract:
Provided are a biaxially oriented polyester film having excellent impact strength and heat resistance, and a method for producing same. The method is for producing a biaxially stretched polyester film and includes the steps A to D indicated below. Step A: a step in which a composition containing a polyester resin in which Tc - (Tg+Tm)/2 is -25ºC to 30ºC inclusive is melt-extruded and an unstretched polyester resin composition sheet is obtained. Step B: a step in which the unstretched polyester resin composition sheet obtained in step A is heated in a range of Tg of the polyester resin + 5 (ºC) to Tg of the polyester resin + 40 (ºC) inclusive, stretching is performed in the lengthwise direction in a range in which the stretch ratio is 2-6 times, and a uniaxially oriented polyester resin composition film is obtained. Step C: a step in which the uniaxially oriented polyester resin composition film obtained in step B is heated in a range of Tc of the polyester resin - 46 (ºC) to Tc of the polyester resin + 25 (ºC) inclusive, stretching is performed in the width direction in a range in which the stretch ratio is 4-8 times, and a biaxially oriented polyester resin composition film is obtained. Step D: a step in which the biaxially oriented polyester resin composition film obtained in step C is heated in a range of Tm of the polyester resin - 40 (ºC) to Tm of the polyester resin - 5 (ºC) inclusive while relaxing the film in a range of 3-20% in the width direction thereof.
Inventors:
SHIMIZU TOSHIYUKI (JP)
HAYAKAWA SHOTA (JP)
KAWAGUCHI KENTA (JP)
HIGASHIURA SHINYA (JP)
HAYAKAWA SHOTA (JP)
KAWAGUCHI KENTA (JP)
HIGASHIURA SHINYA (JP)
Application Number:
PCT/JP2020/047015
Publication Date:
June 24, 2021
Filing Date:
December 16, 2020
Export Citation:
Assignee:
TOYO BOSEKI (JP)
International Classes:
B29C55/14; B29C48/08; C08J5/18; B29K67/00; B29L7/00
Foreign References:
| JP2002086556A | 2002-03-26 | |||
| JPH10249933A | 1998-09-22 | |||
| JP2019172812A | 2019-10-10 | |||
| JP2017074750A | 2017-04-20 |
Other References:
See also references of EP 4079491A4
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