PURPOSE: Titled foamed product suitable as a heat insulating material for a refrigerating cycle, comprising compactly adhering foamed particles consisting of a polymer blend containing a polyphenylene ether graft copolymer and a polystyrene polymer.

CONSTITUTION: A highly heat-resistant foamed product having a density of below 0.05g/cm3, a steam permeation rate of below 0.9g/m2.hr, a thermal conductivity of below 0.035Kcal/m.hr.°C and a heat resistance of at least 90°C, comprising compactly adhering foamed beads comprising a polymer blend prepared by blending a polyphenylene ether graft copolymer prepared by graft-polymerizing (A) a polyphenylene ether represented by the formula, wherein R1 and R2 are each 1W4C alkyl or halogen and n is a polymerization degree, with (B) a styrene compound, with (C) a polystyrene polymer. The component (A) has a polymerization degree of 40W280. The component (B) is present preferably in an amount of 20W200pts.wt. per 100pts.wt. of the component (A) and the component (A) is present preferably in an amount of 20W80wt%, based on the polymer blend.