| 摘要 |
<p>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 to 40°C and thereafter the sheet is alternately heated and cooled as it passes through successive stretching stages, before final cooling to below 60°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.</p> |
