TWI736708B

Provided is a polypropylene-based composite film comprising at least two layers, A and B. The A layer is formed from a layer that contains a propylene-based random copolymer as a primary component. The B layer is formed from a layer that contains a propylene-based random copolymer as a primary component and includes, as a secondary component, a propylene-based block copolymer containing: a homopolypropylene or a propylene-(ethylene or butene) copolymer (component a) having an ethylene or butene content of 0-1.5 wt% at a quantity of 60-90 wt% of the overall polymer; and a propylene-(ethylene or butene) copolymer (component b) having an ethylene or butene content of 20-50 wt% at a quantity of 10-40 wt% of the overall polymer. At least 100-5000 ppm of a fatty acid amide-based lubricant is added to the layer forming the B layer. In the propylene-based block copolymer used in the B layer, the proportion of xylene-insoluble material at 20°C, the intrinsic viscosity of the insoluble material, and the intrinsic visco