| 摘要 |
PURPOSE:To make it possible to form a desired resin into a film stably for a longer period that has a higher foaming rate and uniform cell sizes, by coextruding non-foamed layers of a polyolefin as inner and outer layers and formed layer of a polyolefin or an inorganic compound-containing polyolefin as an intermediate layer. CONSTITUTION:A polyolefin for constituting a non-foamed layer and 30-90wt. pts. polyolefin and 70-10wt.pts. inorganic filler and a foaming agent for constituting a foamed layer are fed to respective extruders, and the discharge amount from each of the discharge devices of the extruders is controlled to obtain the intended thickness ratio, and three layers, that is, an inner layer comprising a non-foamed layer, an intermediate layer comprising a foamed layer, and an outer layer comprising a non-foamed layer are coextruded into a film by the film blowing method using a die. Thus, the higher foaming rate becomes stable, the trouble of adhering of flash to the die is freed, and the operation can be carried out for a longer period of time to provide a favorable foamed film. The constituents of the three layers can be selected for individual purposes to give a wider performance. |
