Patent ID: 8636930

Claim:
A method for producing a thermal insulation foamed sheet comprising: a first step of forming a foaming plane made of a continuous foamed cell group by heating a sheet in which a synthetic resin film is laminated on base paper and by foaming the synthetic resin film mainly using moisture contained in the base paper; and a second step of increasing the foaming height of the foaming cell by at least a part is vacuum-suctioned in a die whose size is set so that a gap for suctioning a foaming cell is generated between said foaming plane and a suctioning surface provided in the die, wherein an expansion ratio of the foaming cell is higher in the second step than the first step, further including said expansion ratio in the first step being a ratio of the height immediately after first step expansion to a height immediately prior to first step expansion and said expansion ratio in the second step being a ratio of the height immediately after second step expansion to a height immediately prior to second step expansion.