Toyobo Co., Ltd.

Kazuhito Horinouchi

Mahiro Nakano

Toru Imai

Kouji Yamada

Kensuke Taneki

The invention provides 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 formula S≥0.00020×t, a relationship between a loop stiffness stress (S [mN]) in a width direction and the thickness (t [μm]) satisfies the formula S≥0.0010×t, 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.

Biaxially oriented polypropylene film

The invention provides a biaxially oriented polypropylene film with a storage elastic modulus (E'-23) of at least 2.0 GPa in a longitudinal direction and at least 6.0 GPa in a width direction, a storage elastic modulus E′ (E′-80) of at least 1.0 GPa in the longitudinal direction and at least 3.0 GPa in the width direction, a ratio (E′-80/E′-23) of E′-80 to E′-23 of at least 0.4 in both the longitudinal direction and the width direction, a heat shrinkage rate at 150° C. of not higher than 10% in the longitudinal direction and not higher than 30% in the width direction, a heat shrinkage rate at 120° C. of not higher than 2.0% in the longitudinal direction and not higher than 5.0% in the width direction, and a heat shrinkage rate at 120° C. in the longitudinal direction that is lower than the heat shrinkage rate at 120° C. in the width direction.

Provided is a biaxially oriented polypropylene film that has high stiffness, has excellent heat resistance at a high temperature of 150° C., easily maintains a bag shape when being made into a packaging bag, and has less pitch shift during printing or fewer wrinkles in a sealed portion when being heat-sealed. A biaxially oriented polypropylene film, wherein a maximum elongation of the biaxially oriented polypropylene film at 150° ° C. or lower measured by a thermomechanical analyzer (TMA) is not larger than 1.5 mm in a longitudinal direction and not larger than 0.1 mm in a width direction, 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.

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Otsu, Japan

Kazuhito Horinouchi