| 摘要 |
PROBLEM TO BE SOLVED: To efficiently and inexpensively produce a resin film sheet of which only the interior is subjected to micro-foaming. SOLUTION: When a polyolefin resin is extruded from a die 5 by using three extruders 1-3, a foaming material is mixed with the polyolefin resin raw material extruded from the central extruder in a ratio of 3-20% by wt. of the raw material. In the execution mode at this time, the polyolefin resin with a density of about 0.4-1.4 is used and the thickness (w) of a multilayered resin film is set to about 0.03-1.4μm and, as a concrete example of the polyolefin resin, a polyethylene resin or a polypropylene resin is used and a proper amt. of additives such as titanium, an antistatic agent, a tire retardant, calcium carbonate, an insecticide, pigment or the like are mixed in the use of outer layers b1, b2. The resin of the outer layers is supplied in an amt. larger than the amt. of the resin of an inner layer to be extruded from the die. |
