| 摘要 |
PROBLEM TO BE SOLVED: To provide an expandable polystyrene resin particle that affords a polystyrene resin foam-molded item excellent in mechanical strengths and external appearances in a reduced time under either of a low-pressure molding condition and a high-pressure molding condition. SOLUTION: The expandable polystyrene resin particle is composed of polystyrene and contains 1.7-5.0 wt.% of a physical expanding agent and 0.5-2.0 wt.% of an expanding auxiliary, where the polystyrene resin has a Z-average molecular weight Mz of 1,000,000-1,500,000 with a ratio Mz/Mw of the Z-average molecular weight Mz to the weight-average molecular weight Mw of 2.5-3.5 and an expansion ratio SR (A/B) of the outer diameter A of a resin strand to an inner diameter B of an orifice of 1.5-3.0 at the time of measurement of the melt flow rate under a condition of 200°C and a load of 49 N. COPYRIGHT: (C)2008,JPO&INPIT
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