US Patent 8,785,508 (July 22, 2014), "Pre-Expanded Polypropylene Resin Beads and Process for Producing same," Taro Kiguchi (Kaneka Corp., Osaka, Japan).
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 a washing of the beads with a chemical such as nitric acid or phosphate soda 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 are expanded and fused 2 to 60 times their original volume without washing before molding.
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|Title Annotation:||INDUSTRY PATENTS|
|Article Type:||Brief article|
|Date:||Nov 1, 2014|
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