METHODS FOR PRODUCING STYRENE RESIN EXTRUDED FOAMS, AND FOAMS PRODUCED THEREBY

摘要

Processes for extrusion foaming styrene resins, in which an expanding agent that is as environmentally safe as possible is injected into a styrene resin and by which foams excellent in heat insulating properties and compressive strength can be produced with excellent stability. The processes are characterized by using as the expanding agent a mixture comprising ether in an amount of 5 wt.% or above but below 40 wt.% based on the total amount of the mixture and C3-C5 saturated hydrocarbons in an amount exceeding 60 wt.% but up to 95 wt.%, in which part of the hydrocarbons may be replaced by fluorohydrocarbons with concern for the environment, and, if necessary, by stretching the extrudate under re-heating to adjust the Z/X ratio (wherein X is the average diameter of the cells constituting the foam in the direction of extrusion; and Z is that in the thicknesswise direction) to 1 or below, preferably 0.8 or below.