| 摘要 |
<p>A method of producing a biaxially oriented film including a thermoplastic polymer material, where the method includes the steps of: sequential stretching the film using at least one pair of mutually 5 intermeshing grooved rollers including alternating grooves and crests, where the rollers are either circular or helical and are adapted to stretch the film in a direction perpendicular to the machine direction or forming a small angle to the direction perpendicular to the machine direction, and where the crests on at least one of the rollers in the at least one pair of rollers have edges which are 10 sufficiently sharp to produce thinner webs on each side of the crest edges during stretching, and where a distance between each crest on one roller and adjacent crests on the other roller is sufficient to avoid the film being squeezed therebetween, and where the intermeshing between the grooved rollers is limited such that two adjacent thinner webs formed on the edges do not grow together to 15 form a single thinner web during the passage of the film between the mutually intermeshing grooved rollers, and prior to, subsequent to, or prior to and subsequent to the sequential stretching, continuously stretching the film substantially in its longitudinal direction, to form a film including a pattern of parallel, continuous or substantially 20 continuous, linearly extending thinner webs oriented substantially in a transverse film direction and between the thinner webs thicker bosses and which are oriented substantially in a longitudinal film direction.</p> |
