LID MATERIAL FOR PRESS-THROUGH PACK

PURPOSE:To provide a lid material having transparency and high moistureproof reliability, easy in disposal treatment and also pref. from the aspect of recycling. CONSTITUTION:A heat-sealable resin layer 2 is provided on the single surface of a biaxially or uniaxially stretched film 1 composed of polypropylene or a copolymer thereof, polypropylene having a photodecomposition promotor added thereto or a copolymer thereof and subsequently irradiated with electron beam or ultrasonic rays to form a lid material 3. The heat-sealable resin layer 2 may be provided after the film 1 is irradiated with electron beam or ultraviolet rays. Since the film 1 generates photodeterioration, the lid material 3 becomes an openability imparted state and has high moistureproof reliability because the generation rate of a pinhole of the lid material is extremely low as compared with aluminum foil. When a polypropylene sheet is used as a bottom material 4, a press-through pack becomes a single material and is excellent in recycling properties and, since the whole of the pack becomes a plastic material even in other material quality, the pack is pref. from the aspect of disposal treatment and incineration.