| 摘要 |
The 4-methyl-1-pentene copolymer multi-layer film according to the present invention is a three-layer laminate or a five-layer laminate, which comprises a layer (A) comprising 4-methyl-1-pentene, a layer (B) comprising polypropylene or polyethylene, and optionally, a layer (C) comprising an adhesive resin, said layer (A) being provided on each surface of the layer (B) in the three-layer laminate or being provided on each surface of the layer (B) through the layer (C) in the five-layer laminate, and this multi-layer film is uniaxially stretched in a stretch ratio of not less than 2 times or biaxially oriented in a stretch ratio of not less than 1.5 times in each of the machine direction and the transverse direction. The process for producing a 4-methytl-1-pentene copolymer multi-layer film according to the present invention comprises uniaxially stretching the three-layer laminate or the five-layer laminate in a stretch ratio of not less than 2 times, or comprises biaxially orienting the three-layer laminate or the five-layer laminate in a stretch ratio of not less than 1.5 times in each of the machine direction and the transverse direction. The multi-layer film of the invention has high rigidity and excellent releasability from a black oxidated copper foil, and is suitable as a release film for MLB production. In the process for producing a multi-layer film according to the invention, stretching unevenness and breaks hardly occur in the stretching operation and the productivity is good.
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