| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject polypropylene based resin having high melt tension, low in coloration, high mechanical strength or stiffness and satisfactory in moldability by treating a polypropylene based resin having an index concerning with dynamic viscoelasticity in a specific relation, under exposure to ionizing radiation. SOLUTION: A polypropylene based resin that satisfies formula: PI>=4.0 in which PI is 105 times of a value of an inverse number of a storage elastic modulus at an intersection of a frequencyωdependence curve G'(ω) of a storage elastic modulus in a dynamic viscoelasticity measurement and a frequencyωdependence curve G"(ω) of a loss modulus and a melt tension (MT) satisfies a formula [MT is a load (g) observed in winding a strand extruded at 230 deg.C using a nozzle (diameter; 2.095 mm, L/D=3.8) at 15 mm/min into air at 23 deg.C and winding at 6.4 m/min], is treated under exposure to ionizing radiation. The preferable radiation dose of the ionizing radiation is 1-80 kGy ofγ-ray.
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