Oriented polymeric articles and method

Abstract

Stretched articles, such as oriented polymeric films or fibers, having microstructure features on at least one surface thereof, and processes for making such articles, are disclosed. A method of making fibers comprises forming a polymeric film having a body having a first surface and a second surface and having a longitudinal dimension. The film also comprises a plurality of elongate microstructure features disposed on the first surface of the body in a direction substantially parallel to the longitudinal dimension of the body, wherein the elongate microstructure features are substantially parallel. The method further comprises stretching the polymeric film in a direction substantially parallel to the longitudinal dimension of the body, and fibrillating the stretched polymeric film along the longitudinal dimension of the body to provide one or more fibers, wherein each fiber has at least one microstructure feature thereon.

1 . A polymeric fiber comprising:
 a fiber body having a first surface and a second surface, and a longitudinal dimension, and   one or more elongate microstructure features disposed on the first surface of the fiber body in a direction substantially parallel to the longitudinal dimension of the fiber body, wherein any plurality of microstructure features are substantially parallel.   
     
     
         2 . The fiber of  claim 1  wherein the fiber has a stretch ratio of at least 1.5 in the longitudinal dimension of the fiber body. 
     
     
         3 . The fiber of  claim 1  wherein the fiber body has a first thickness, wherein the microstructure features have a second thickness, and wherein the ratio of the first thickness to the second thickness is at most 2. 
     
     
         4 . The fiber of  claim 1  wherein one or more of the microstructure features has a discontinuity. 
     
     
         5 . The fiber of  claim 1  wherein one or more of the mictrostructure features has a plurality of discontinuities. 
     
     
         6 . The fiber of  claim 1  wherein at least two adjacent microstructure features are spaced apart laterally by a separation span of the fiber body. 
     
     
         7 . The fiber of  claim 1  wherein the polymeric fiber is an electret. 
     
     
         8 . The fiber of  claim 1  wherein at least one of the microstructure features is shaped to enhance electrical field effects. 
     
     
         9 . A fiber array comprising a plurality of polymeric fibers of  claim 1 , wherein the fiber bodies of the fibers in the array are substantially parallel. 
     
     
         10 . The invention of  claim 9  wherein a first layer of fibers is defined by a fiber array of claim  76  that is aligned in a first direction, wherein a second layer of fibers is defined by a fiber array of claim  76  that is aligned in a second direction, and wherein the second layer overlies the first layer. 
     
     
         11 . The invention of  claim 10  wherein at least some of the microstructure features on the fibers of the first layer engage the second surfaces of the fiber bodies of the fibers of the second layer. 
     
     
         12 . The invention of  claim 10  wherein the first and second directions are different. 
     
     
         13 . The invention of  claim 10  wherein the first and second directions are substantially parallel. 
     
     
         14 . The fiber of  claim 1  wherein the polymeric fiber is microporous. 
     
     
         15 . The fiber of  claim 14  wherein the microporous polymeric fiber contains particles. 
     
     
         16 . The fiber of  claim 1  wherein the fiber body has a first thickness, wherein the microstructure features have a second thickness, and wherein the ratio of the first thickness to the second thickness is at most 1. 
     
     
         17 . The fiber of  claim 1  wherein the fiber body has a first thickness, wherein the microstructure features have a second thickness, and wherein the ratio of the first thickness to the second thickness is at most 0.5. 
     
     
         18 . The fiber of  claim 1  wherein the fiber body has a first thickness, wherein the microstructure features have a second thickness, and wherein the ratio of the first thickness to the second thickness is at most 0.1. 
     
     
         19 . The fiber of  claim 1  wherein the film is adsorbent. 
     
     
         20 . The fiber of  claim 1  wherein the film is absorbent.