| 摘要 |
PROBLEM TO BE SOLVED: To improve a high frequency welding processability by providing a polypropylene composition layer made of a specific crystalline propylene-α- olefin copolymer to vertically sandwich a layer made of a specific ethylene copolymer therebetween to form it in a three-layer structure. SOLUTION: Polypropylene compositions each having a limiting viscosity [η]RC=6.5 dl/g or below of a crystalline propylene-α-olefin copolymer R having a propylene content of 90 to 99 wt.% and a crystal melting point of 160 deg.C are laminated on both surfaces of a layer made of an ethylene copolymer having a cohesive energy density of 60 to 90 cal/cm3, a melt flow rate of 1,0 to 15.0 g/10 min, a crystal melting point of 50 to 120 deg.C, a Vicat softening point of 100 deg.C or below and a peak value of a dielectric loss tangent of 5.0×10-3 (100 kHz) or above.
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