Abstract: The said invention relates to an extrusion molding machine (11), which is composed of a storage bin (30) supplying foam material (1), a cylinder (50) and a screw (70) for mixing and transporting foam material (1) from storage bin (30), a tank (40) provided with piping connecting storage bin (30) and screw (70) and storing water (41), a mold (80) connecting to the front end (6) of cylinder (50), and a heater (60) for melting the foam material (1) and at the same time heating water in six stages from the initial temperature below the boiling temperature of water (41) to the final temperature of total vaporization, from cylinder (50) bottom at storage bin (30) side to cylinder (50) front end (6) at mold (80) side.

Abstract: A foamed material constituting a thermal insulator (360) which comprises 50 wt % or more of a non-resin component, preferably 50 to 70 wt % of a mixture of cellulose, starch and a poly(vinyl alcohol). In a more preferable embodiment, the foamed material contains 30 wt % of cellulose, 25 wt % of starch and poly(vinyl alcohol 2C, 0.7 wt % of an antioxidant, 0.2 wt % of a mildewproofing agent, 0.2 wt % of a pigment and 43.9 wt % of a polyolefin resin (2), wherein the antioxidant is a phenol type antioxidant having a melting point of 110° C. being lower than that of the polyolefin resin.