| 摘要 |
PURPOSE:To lower welding temp., to increase a bag making speed, to enhance production efficiency and to conserve energy by forming the welding part to a bag main body based on a specific ethylene/vinyl acetate copolymer resin. CONSTITUTION:A male fastener 2 and a female fastener 3 are formed to two layers of the welding parts 2A, 3A to a bag main body 4 and the residual parts 2B, 3B containing a fastening body and the welding parts 2A, 3A to the bag main body 4 are formed based on an ethylene/vinyl acetate copolymer resin containing 1-9% of vinyl acetate and having a melt index of 0.5-6.0g/10min and the residual parts 2B, 3B may be formed from other resin. As other resin, low density polyethylene or straight chain polyethylene is designated. By forming a multilayer structure from the resin based on the ethylene/vinyl acetate copolymer resin and other resin, the engaging strength or openability of the fastener 1 can be properly adjusted. When the melt index is below 0.5g/10min and exceeds 6.0g/10min, engageness becomes inferior because of the inferiority of shape retentivity. When the content of vinyl acetate is below 1%, seal temp. lowering effect is reduced and, when said content exeeds 9%, engaging force becomes inferior because the flexibility is too high.
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