Method for producing skin-covered, expanded bead molded article

Patent metadata

Field	Value
Publication number	US-2016017108-A1
Application number	US-201514792763-A
Country	US
Kind code	A1
Filing date	Jul 7, 2015
Priority date	Jul 18, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

A method for producing a skin-covered molded article including filling polypropylene-based resin expanded beads in a hollow space of a thermoplastic resin skin and feeding steam into the hollow space to fusion-bond the expanded beads together, the expanded beads showing specific DSC characteristics involving a specific high temperature peak(s) with specific heat of fusion.

First claim

What is claimed is:

1 . A method for producing a skin-covered, expanded bead molded article comprising the steps of:
providing a skin of a thermoplastic resin molded article defining a hollow space therewithin; filling polypropylene-based resin expanded beads in the hollow space; and then feeding a heating medium into the hollow space through one or more heating medium feeding pins inserted into the hollow space to fusion-bond the expanded beads to each other and to form an expanded bead molded article that is covered with the skin; wherein the polypropylene-based resin expanded beads are prepared from a polypropylene-based resin having a melting point of 140 to 155° C., wherein the polypropylene-based resin expanded beads have such a crystal structure that gives a DSC curve when a measurement specimen sampled from the polypropylene-based resin expanded beads is heated from 23° C. to 200° C. at a heating speed of 10° C./min, said DSC curve having an intrinsic endothermic peak intrinsic to the polypropylene-based resin constituting the polypropylene-based resin expanded beads and at least one high temperature endothermic peak which is located on a higher temperature side of the intrinsic endothermic peak,
wherein a total heat of fusion ΔHt of the entire endothermic peaks of the DSC curve is more than 75 J/g,
a ratio ΔH2/ΔHt of a total heat of fusion ΔH2 of said at least one high temperature endothermic peak to the total heat of fusion ΔHt is 0.20 to 0.30, and
a heat of fusion of that portion of said at least one high temperature endothermic peak which is higher than the peak top temperature of a lowest temperature peak is 6 J/g or more, said lowest temperature peak being that high temperature endothermic peak which has the lowest peak top temperature among the peak top temperatures of said at least one high temperature endothermic peak.

2 . The method according to claim 1 , wherein the thermoplastic resin molded article is obtained by blow molding and wherein the polypropylene-based resin expanded beads are filled in the hollow space of the thermoplastic resin molded article while the thermoplastic resin molded article is in a softened state.

3 . The method according to claim 1 , wherein the polypropylene-based resin expanded beads have a bulk density of 20 to 60 kg/m 3 .

4 . The method according to claim 1 , wherein the thermoplastic resin molded article is formed of a polypropylene-based resin.

Assignees

• Jsp Corp

Inventors

• Tokiwa Tomoo

Classifications

• B29C44/343

  by using pipes to direct the steam inside the mould · CPC title

• B29K2105/048

  Expandable particles, beads or granules · CPC title

• B29K2995/0063

  Density · CPC title

• C08J2203/06

  CO2, N2 or noble gases · CPC title

• C08J9/18

  by impregnating polymer particles with the blowing agent · CPC title