| 摘要 |
A porous film for a heat-sealable bag-constituting member is prepared by stretching an unstretched film to be porous. The unstretched film includes an ultrahigh-molecular-weight polyethylene having a weight-average molecular weight of 30×104 to 250×104, a polyolefin component other than the ultrahigh-molecular-weight polyethylene, and an inorganic filler as essential components, and the content of the ultrahigh-molecular-weight polyethylene is 1 percent by weight or more based on the total amount of polymer components constituting the porous film. Even when produced by stretching at a low draw ratio, the film does not suffer from uneven stretching and shows high productivity. When the film is heat-sealed into a bag, the bag has a high seal strength and does not suffer from edge tear. The film is therefore useful particularly as a bag-constituting member to be heat-sealed into a bag typically as a disposable body warmer.
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