Maro Publications

Polypropylene Foams


From 09/16/2014 through 4/3/2013

Maro Encyclopedia



Patent Abstracts

Patent Titles

Polypropylene (PP)




1. “From movement toward plastic material integration in various industries in recent years, particularly a polypropylene resin is expanding industrial fields because of its excellence in the balance among mechanical strength, heat resistance, processability and price and because of its excellent properties in easy combustibility and easy recyclability. Similarly, polypropylene resin foamed bead molded articles obtained by molding of polypropylene resin foamed beads can be endowed with characteristics such as lightweight properties, shock-absorbing characteristics and thermal insulating properties without losing excellent properties of the polypropylene resin and are thus widely used as packaging materials, building materials, insulator materials, automotive materials etc.

A polypropylene resin foamed bead molded article obtained by molding polypropylene resin foamed beads is superior to a polystyrene resin foamed bead molded article in heat resistance, chemical resistance, rigidity, and compression strain recovery. On the other hand, when polypropylene resin foamed beads are secondarily foamed and simultaneously fused in molding, high-temperature heating as compared with molding of polystyrene resin foamed beads, that is, heating by steam at high saturation vapor pressure, is necessary. Accordingly, a mold with high pressure-proof specifications and a dedicated molding machine for high press pressure are necessary, and energy costs used therefor is also high.”

(Polypropylene Foam, Wikipedia, 4/3/2013)

2. Pre-expanded polypropylene beads are used for molding electronic packaging.  However, residual dispersion agents retard fusion of the pre-expanded beads during in-mold foaming requiring washing with a chemical such as nitric acid or phosphate soda of the beads before molding.  Kiguchi prepared antistatic pre-expanded polypropylene beads by soaking PP pellets containing the antistatic glycerin esters in a water dispersion of foaming and dispersion agents.  The dried pellets be expanded and fused 2 to 60 times the original volume without washing before molding. 
US Patent 8,785,508 (July 22, 2014), “Pre-Expanded Polypropylene Resin Beads and Process for Producing same,” Taro Kiguchi (Kaneka Corporation, Osaka, Japan).


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(RDC 6/5/2012)


Roger D. Corneliussen

Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921


Copyright 2013 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen

* Date of latest addition; date of first entry is 4/3/2013.