| 摘要 |
Fibrous polyolefin nonwoven sheets are bonded and stretched in a continuous, multiple stage process. First, the sheet is heated without significant stretching to a temperature that is close to, but below, the melting temperature of the polyolefin. Then, as the sheet is forwarded to a first stretching stage, the sheet temperature is decreased by 5 DEG to 40 DEG C. and thereafter the sheet is alternately heated and cooled as it passes through successive stretching stages, before final cooling to below 60 DEG C. In comparison to similar sheets bonded and stretched at constant temperature, the sheets produced by the process of the present invention are significantly more uniform in thickness.
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