Stretched polymeric films can be used in a variety of applications, including optical applications. The stretching conditions and shape of the stretching tracks in a stretching apparatus can determine or influence film properties. Methods and stretching apparatuses can include adjustable or zone-defined...http://www.google.com.tw/patents/US7316558?utm_source=gb-gplus-share專利 US7316558 - Devices for stretching polymer films
