ALKENYL AROMATIC FOAM WITH LOW SOLUBILITY HYDROFLUOROCARBON

摘要

Prepare a closed-cell alkenyl aromatic polymer foam by an extrusion process using a blowing agent composition that contains at least 30 weight-percent of the chlorine-free hydrof luorocarbon blowing agent such that the foam has a density of 48 kilograms per cubic meter or less, contains more than 50 weight-percent styrene-acrylonitrile copolymer based on total polymer weight and at least eight weight- percent of a chlorine-free hydrof luorocarbon blowing agent that has a lower solubility in polystyrene than 1,1,2,2- tetrafluoroethane (HFC-134).