Method of forming hollow foam moldings
AssigneeJsp Corporation
InventorsDiasuke Imanari, Kenichi Takase, Masayasu Okuda, Masato Naito
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Abstract
A method for producing a hollow foam molding having a thin and uniform wall thickness, including extruding a foamable melt containing a polypropylene resin having an equilibrium compliance Jeo of 0.5×10−3 to 1.8×10−3 Pa−1 and a swell ratio Sw of 2.5 or less and a physical blowing agent through a die to obtain a parison having a softened polypropylene resin foam layer, placing the parison in a mold, and blowing a gas into the parison to obtain a hollow foam molding having a hardened polypropylene resin foam layer with an apparent density of 0.35 to 0.65 g/cm3.
Claims7
A method for producing a tubular hollow foam molding having an average wall thickness of 1.0 to 3.0 mm and a thickness variation coefficient Cv of 50% or less, said method comprising the steps of:
- (a) extruding a foamable melt comprising a polypropylene resin and a physical blowing agent through a die to obtain a tubular parison having a softened polypropylene resin foam layer, said polypropylene resin foam layer having throughout an equilibrium compliance Jeo of 0.5×10−3 to 1.8×10−3 Pa−1 and a swell ratio Sw of 2.5 or less;
- (b) placing said tubular parison in a mold;
- and
- (c) blowing a gas into said tubular parison to blow mold said tubular parison, thereby obtaining the tubular hollow foam molding having a hardened polypropylene resin foam layer with an apparent density of 0.35 to 0.65 g/cm3,
- wherein said physical blowing agent is used in an amount of 0.01 to 1.2 mols per 1 kg of said polypropylene resin.
Dependencies are inferred from the claim text.