	US 12,252,597 B2
	Biaxially oriented polypropylene film
Kouji Yamada, Otsu (JP); Kazuhito Horinouchi, Otsu (JP); Mahiro Nakano, Inuyama (JP); and Toru Imai, Inuyama (JP)
Assigned to TOYOBO CO., LTD., Osaka (JP)
Appl. No. 17/417,831
Filed by TOYOBO CO., LTD., Osaka (JP)
PCT Filed Dec. 19, 2019, PCT No. PCT/JP2019/049810 § 371(c)(1), (2) Date Jun. 24, 2021, PCT Pub. No. WO2020/137793, PCT Pub. Date Jul. 2, 2020.
Claims priority of application No. 2018-247986 (JP), filed on Dec. 28, 2018; and application No. 2019-195473 (JP), filed on Oct. 28, 2019.
Prior Publication US 2022/0081521 A1, Mar. 17, 2022
Int. Cl. C08J 5/18 (2006.01); B29C 48/00 (2019.01); B29C 48/08 (2019.01); B29C 55/00 (2006.01); B29C 55/14 (2006.01); B29K 23/00 (2006.01); B29L 7/00 (2006.01)

CPC C08J 5/18 (2013.01) [B29C 48/0018 (2019.02); B29C 48/022 (2019.02); B29C 48/08 (2019.02); B29C 55/005 (2013.01); B29C 55/14 (2013.01); B29K 2023/12 (2013.01); B29L 2007/008 (2013.01); C08J 2323/12 (2013.01)]

14 Claims

1. A biaxially oriented polypropylene film, wherein

a relationship between a loop stiffness stress (S [mN]) in a longitudinal direction and a thickness (t [μm]) satisfies the following formula,

S≥0.00020×t³,

a relationship between a loop stiffness stress (S [mN]) in a width direction and the thickness (t [μm]) satisfies the following formula,

S≥0.0010×t³, and

a heat shrinkage rate of the biaxially oriented polypropylene film at 150° C. is not higher than 10% in the longitudinal direction and not higher than 30% in the width direction, a heat shrinkage rate of the biaxially oriented polypropylene film at 120° C. is not higher than 2.0% in the longitudinal direction and not higher than 5.0% in the width direction, and the heat shrinkage rate at 120° C. in the longitudinal direction is lower than the heat shrinkage rate at 120° C. in the width direction.