Foaming of plastics which are not excitable in AC field - by using blowing agent which releases gas in AC field

摘要

Mfr. of foam of plastics which are not or only little capable of being excited when subjected to the action of an electric alternating field, comprises using a gas which has been formed by decomposition of an expanding agent, admixed to the plastics; such decomposition having been caused by the alternating field. Used e.g. in the mfr. of polystyrene or polyethylene foam film webs. Mfr. is simplified, hence rendered more economical, in that use of 2-stage, so-called cascade is no longer necessary.