Film structures and methods of making film structures

Abstract

A method of making a three-dimensional film structure which film structure comprises making separable surface elements on a surface portion of a film structure and stretching the film structure to separate the separable surface elements, thereby obtaining a desired surface structure and tear properties. The separable surface elements are provided using a cut film surface.

What is claimed is:  
     
         1 . A method of forming an oriented film structure comprising: 
 providing a film structure of an orientable polymer which has first and second major surfaces; and scoring or cutting at least one of the major surfaces forming predetermined separable elements; and    inelastically stretching the film structure to separate the separable surface elements across the at least one major surface of the film structure, thereby creating spacings between adjacent separated separable surface elements.    
     
     
         2 . The method of  claim 1 , wherein the film structure including the separable surface elements are formed by at least partially cutting the film structure in at least one direction in a series of substantially parallel lines.  
     
     
         3 . The method of  claim 1  wherein the separable surface elements are formed by at least partially cutting the film structure on both said first and second major surfaces.  
     
     
         4 . The method of  claim 3  wherein the separable surface elements are formed in at least two directions which overlap at an angle of from 10 to 170 degrees.  
     
     
         5 . The method of  claim 2  wherein the film structure is oriented at an angle to the at least one direction.  
     
     
         6 . The method of  claim 4  wherein the film structure is biaxially oriented at least one direction of orientation being at an angle to one of the directions.  
     
     
         7 . The method of  claim 1  wherein the film structure is a multilayer film.  
     
     
         8 . The method of  claim 2  wherein the parallel lines are substantially linear.  
     
     
         9 . The method of  claim 1  wherein the at least one film surface is scored or cut in at least two directions so as to form discrete multiple sided predetermined segments.  
     
     
         10 . An oriented film structure having a first and second major surface and a base layer at least a first major surface having surface elements wherein the base layer is an inelasticly oriented layer.  
     
     
         11 . An oriented film structure of  claim 10  wherein the base layer is an oriented thermoplastic film layer.  
     
     
         12 . An oriented film structure of  claim 11  wherein the base layer is oriented in at least two directions.  
     
     
         13 . An oriented film structure of  claim 11  wherein the base layer is oriented having a thickness of from 2 to 250 micrometers.  
     
     
         14 . An oriented film structure of  claim 11  wherein the base layer is oriented having a thickness of from 10 to 75 micrometers.  
     
     
         15 . An oriented film structure of  claim 10  wherein the surface elements have a height above the base layer of from 5 to 50 micrometers.  
     
     
         16 . An oriented film structure of  claim 10  wherein the surface elements have a width of from 100 to 1000 micrometers.  
     
     
         17 . An oriented film structure of  claim 16  wherein the surface elements are discrete structures each being isolated from its neighbor.  
     
     
         18 . An oriented film structure of  claim 17  wherein the surface elements each are a series of multi-sided segments arranged as a grid.  
     
     
         19 . An oriented film structure of  claim 16  wherein the surface elements are continuous ribs.  
     
     
         20 . An oriented film structure of  claim 17  wherein the surface elements are continuous ribs on both major surfaces of the film structure.  
     
     
         21 . An oriented film structure of  claim 20  wherein the surface elements on opposite faces extend in different directions so that they overlap.  
     
     
         22 . An oriented film structure of  claim 21  wherein the surface elements overlap one opposite face at an angle of from 10 to 170 degrees.  
     
     
         23 . An oriented film structure of  claim 21  wherein the surface elements overlap one opposite face at an angle of from 45 to 135 degrees.  
     
     
         24 . An oriented film structure of  claim 19  wherein the surface elements are substantially linear ribs.  
     
     
         25 . An oriented film structure of  claim 19  wherein the surface elements comprise 10 to 90 percent of the surface area of the film structure.  
     
     
         26 . An oriented film structure of  claim 19  wherein the surface elements comprise 25 to 50 percent of the surface area of the film structure.  
     
     
         27 . An oriented film structure of  claim 19  wherein at least a portion of the surface elements have a width of from 100 to 500 micrometers.  
     
     
         28 . An oriented film structure of  claim 19  wherein at least a portion of the surface elements have a width of from 100 to 1000 micrometers.  
     
     
         29 . An oriented film structure of  claim 11  wherein at least a portion of the surface elements have a height above the base layer of from 5 to 25 micrometers.  
     
     
         30 . An oriented film structure of  claim 11  wherein the surface elements are from 5 to 25 micrometers high above the base layer and the base layer has a thickness of from 10 to 50 micrometers.  
     
     
         31 . An oriented film structure of  claim 11  wherein the film structure base layer is an orientable thermoplastic film.  
     
     
         32 . An oriented film structure of  claim 31  wherein the thermoplastic film is a semicrystalline thermoplastic polymer of amorphous glassy polymer.  
     
     
         33 . An oriented film structure of  claim 31  wherein the thermoplastic film is semicrystalline polymer selected from a linear low density polyethylene, high density polyethylene, ultra high molecular weight polyethylene, isotactic polypropylene, blends of isotactic polypropylene and substantially syndiotactic polypropylene and blends of isotactic polypropylene and polyethylene.  
     
     
         34 . An oriented film structure of  claim 30  wherein the base layer has a thickness of from 2 to 250 micrometers.  
     
     
         35 . An oriented film structure of  claim 34  wherein the base layer has a thickness of from 5 to 150 micrometers.  
     
     
         36 . An oriented film structure of  claim 34  wherein the base layer has a thickness of from 10 to 75 micrometers.  
     
     
         37 . An oriented film structure of  claim 10  wherein the film structure is a single layer film.  
     
     
         38 . An oriented film structure of  claim 10  wherein the film structure is a multilayer film.  
     
     
         39 . The method of  claim 1  wherein the series of parallel lines are intermittent.  
     
     
         40 . The method of  claim 1  wherein the series of parallel lines are continuous.