Patent ID: 7932341

Claim:
A polypropylene polymer film, characterized by having a tensile modulus of 300 MPa to 1,000 MPa under an atmosphere at 23° C. and 60 MPa to 120 MPa under an atmosphere at 120° C., and characterized by having a crystallinity of 65% or more and 73% or less, as calculated according to the following Formula (1) by using the absorbance measured in an infrared spectrophotometer: Crystallinity (%)=109×(( D 998 −D 917 )/( D 972 −D 917 ))−31.4 (1) (wherein D 998 , or D 972 D 917 represents the absorbance at 998 cm −1 , 972 cm −1 , or 917 cm −1 ), and wherein the polypropylene polymer film is composed of propylene copolymer containing 80% or more of propylene.