| 摘要 |
PURPOSE:To obtain the title foam which has stable foaming properties, excellent dimensional stability and appearance, and a high expansion ratio without using a shrinkage preventive by supplying a polyolefin resin contg. a fluorine surfactant together with a specific blowing agent to a foam extruder to thereby foam the resin. CONSTITUTION:The foam is obtd. by mixing a polyolefin resin with a fluorine surfactant having a fluoroalkyl group, supplying the mixture to a foam extruder, supplying 1,1,1,2-tetrafluoroethane as the blowing agent to the extruder to mix it with the resin, and extruding the resulting mixture to foam it. Since a polyolefin resin has a low permeability to 1,1,1,2-tetrafluoroethane, the foam does not undergo dimensional change due to shrinkage. The surfactant acts as an internal lubricant and improves the mixing properties by surfactant effects, enabling an increase in the amt. of the blowing agent added by about 20%. Using an external lubricant makes the surface of the foam smooth. |
