| abstract |
(57) [Summary] [Purpose] In extrusion foaming of polyolefin resins, The quality and workability are improved by mixing and using 3 types of CFC substitutes in the volatile foaming agent. [Structure] When extrusion-foaming a polyolefin resin, a mixture of the following three types is used as a volatile foaming agent. That is, Freon 142b: 5-65 wt%, Freon 22: 5-90 wt%, Freon 134a: 5-35 wt%. |