Vented Tooling Belt for Production of Structured Surfaces

Abstract

Various geometries are described for forming retroreflective structures in polymeric sheets or films. The geometries enable venting of volatile gases that can otherwise become trapped between the embossing surface and the polymeric sheet or film. The geometries are incorporated in tooling belts or other pattern forming surfaces.

What is claimed is: 
     
         1 . A method for reducing occurrence of gases trapped between tooling and a polymeric sheet during manufacture of retroreflective materials, the method comprising:
 providing a substrate defining opposite peripheral edges and a molding surface extending between the edges,   the molding surface including at least two adjacent prismatic structures each having a structure height, the at least two adjacent prismatic structures defining an average structure height, and a channel extending between at least two of the prismatic structures;   providing a polymeric sheet defining at least one face;   embossing a pattern of the plurality of prismatic structures from the substrate to the face of the polymeric sheet;   wherein during the embossing, gases disposed between the substrate and the polymeric sheet are urged through at least a portion of the channels, thereby reducing occurrence of trapped gases.   
     
     
         2 . The method of  claim 1 , wherein the channels define an average depth. 
     
     
         3 . The method of  claim 2 , wherein the average depth is less than the average structure height. 
     
     
         4 . The method of  claim 2 , wherein the average depth is from 5% to 50% of the average structure height. 
     
     
         5 . The method of  claim 2 , wherein the average depth is from 1% to 15% of the average structure height. 
     
     
         6 . The method of  claim 1 , wherein the prismatic structures are triangles arranged so as to define a plurality of baselines separating each triangle from an adjacent triangle. 
     
     
         7 . The method of  claim 6 , wherein the plurality of baselines include a first set of baselines oriented parallel to one another, a second set of baselines oriented parallel to one another and at 60 degrees from the first set of baselines, and a third set of baselines oriented parallel to one another and at 60 degrees from the second set of baselines and at 60 degrees from the first set of baselines. 
     
     
         8 . The method of  claim 7 , wherein the plurality of channels include at least one channel extending along at least one of the first set of baselines, at least one channel extending along at least one of the second set of baselines, and at least one channel extending along at least one of the third set of baselines. 
     
     
         9 . The method of  claim 8 , wherein the plurality of channels extending along at least one of the first set of baselines includes two channels separated by another of the first baselines. 
     
     
         10 . The method of  claim 9 , wherein the plurality of channels extending along at least one of the second set of baselines includes two channels separated by another of the second baselines. 
     
     
         11 . The method of  claim 10 , wherein the plurality of channels extending along at least one of the third set of baselines includes two channels separated by another of the third baselines. 
     
     
         12 . A retroreflective material produced using the method of  claim 1 . 
     
     
         13 . A method of modifying a triangular prismatic structured surface on a substrate, the method comprising:
 providing the substrate defining opposite peripheral edges and a molding surface extending between the edges,   the molding surface including at least two adjacent prismatic structures each having a structure height, the at least two adjacent prismatic structures defining an average structure height, and   forming at least one channel extending between at least two of the prismatic structures to yield a modified substrate,   wherein the substrate is capable of embossing a channeled structure on a product to improve improved light scattering capability.   
     
     
         14 . The method of  claim 13 , wherein the at least one channel define an average depth. 
     
     
         15 . The method of  claim 14 , wherein the average depth is less than the average structure height. 
     
     
         16 . The method of  claim 14 , wherein the average depth is from 5% to 50% of the average structure height. 
     
     
         17 . The method of  claim 14 , wherein the average depth is from 1% to 15% of the average structure height. 
     
     
         18 . The method of  claim 13 , wherein the prismatic structures are triangles arranged so as to define a plurality of baselines separating each triangle from an adjacent triangle. 
     
     
         19 . The method of  claim 18 , wherein the plurality of baselines include a first set of baselines oriented parallel to one another, a second set of baselines oriented parallel to one another and at 60 degrees from the first set of baselines, and a third set of baselines oriented parallel to one another and at 60 degrees from the second set of baselines and at 60 degrees from the first set of baselines. 
     
     
         20 . The method of  claim 19 , wherein the plurality of channels include at least one channel extending along at least one of the first set of baselines, at least one channel extending along at least one of the second set of baselines, and at least one channel extending along at least one of the third set of baselines. 
     
     
         21 . The method of  claim 20 , wherein the plurality of channels extending along at least one of the first set of baselines includes two channels separated by another of the first baselines. 
     
     
         22 . The method of  claim 21 , wherein the plurality of channels extending along at least one of the second set of baselines includes two channels separated by another of the second baselines. 
     
     
         23 . The method of  claim 22 , wherein the plurality of channels extending along at least one of the third set of baselines includes two channels separated by another of the third baselines.