Release liners and processes for making the same

Abstract

Release liners and processes for making the same are disclosed. The release liners include no more than about 1.5 micrograms/square centimeter of nonreacted silicone materials (extractables). The release liners are prepared using solvent coating of radiation curable silicone release materials.

That which is claimed:  
     
         1 . A release liner comprising: 
 a substrate having opposing surfaces; and    a radiation cured silicone release coating on a surface thereof, said coating comprising no more than about 1.5 micrograms per square centimeter total extractables.    
     
     
         2 . The release liner of  claim 1 , wherein said coating comprises no more than about 0.9 micrograms per square centimeter total extractables.  
     
     
         3 . The release liner of  claim 2 , wherein said coating comprises no more than about 0.2 micrograms per square centimeter total extractables.  
     
     
         4 . The release liner of  claim 1 , wherein said coating further comprises no more than about 10 ppm volatile compounds.  
     
     
         5 . The release liner of  claim 4 , wherein said coating comprises no more than about 2.0 ppm volatile compounds.  
     
     
         6 . The release liner of  claim 1 , wherein said coating further exhibits substantially no transfer of uncured silicone to adjacent surfaces.  
     
     
         7 . The release liner of  claim 1 , further comprising a second release coating on a surface of said substrate opposite said radiation cured silicone release coating.  
     
     
         8 . The release liner of  claim 7 , wherein said second release coating also comprises no more than about 1.5 micrograms per square centimeter total extractables.  
     
     
         9 . The release liner of  claim 1 , wherein said substrate comprises a polyolefin coated paper.  
     
     
         10 . The release liner of  claim 1 , wherein said substrate comprises a polymer film.  
     
     
         11 . The release liner of  claim 10 , wherein said polymer film comprises a film selected from the group consisting of polyolefin, polyester, polyvinyl chloride, polyamide, polystyrene, co-polyester, polycarbonate, and polyketone films.  
     
     
         12 . A process for making a release liner, comprising the steps of: 
 applying a composition comprising a radiation curable silicone release agent in an organic solvent to a surface of a substrate;    treating said coated substrate under conditions sufficient to remove substantially all of said solvent; and    exposing said coated substrate to radiation under conditions sufficient to substantially cure said radiation curable silicone release agent to form a radiation cured silicone release coating.    
     
     
         13 . The process of  claim 12 , wherein said composition comprises about 1 to about 90 weight percent radiation curable silicone release agent and about 99 to about 10 weight percent solvent.  
     
     
         14 . The process of  claim 13 , wherein said composition comprises about 4 to about 20 weight percent radiation curable silicone release agent and about 96 to about 80 weight percent solvent.  
     
     
         15 . The process of  claim 14 , wherein said composition comprises about 6 to about 15 weight percent radiation curable silicone release agent and about 94 to about 85 weight percent solvent.  
     
     
         16 . The process of  claim 12 , wherein said solvent is selected from the group consisting of aliphatic solvents, cycloaliphatic solvents, aromatic solvents, ketone solvents, and mixtures thereof.  
     
     
         17 . The process of  claim 16 , wherein said aliphatic solvent is selected from the group consisting of hexane, heptane, and mixtures thereof.  
     
     
         18 . The process of  claim 16 , wherein said cycloaliphatic solvent is cyclohexane.  
     
     
         19 . The process of  claim 16 , wherein said aromatic solvent is selected from the group consisting of xylene, toluene, and mixtures thereof.  
     
     
         20 . The process of  claim 16 , wherein said ketone solvent is selected from the group consisting of methyl ethyl ketone, cyclohexanone, methyl iso-butyl ketone, and mixtures thereof.  
     
     
         21 . The process of  claim 12 , wherein said applying step comprises applying said composition in an amount sufficient to provide a coating weight of about 0.1 to about 1.0 grams per square meter (dry).  
     
     
         22 . The process of  claim 21 , wherein said applying step comprises applying said composition in an amount sufficient to provide a coating weight of about 0.1 to about 0.6 grams per square meter (dry).  
     
     
         23 . The process of  claim 22 , wherein said applying step comprises applying said composition in an amount sufficient to provide a coating weight of about 0.1 to about 0.3 grams per square meter (dry).  
     
     
         24 . The process of  claim 12 , wherein said treating step comprises heating said coated substrate, optionally in the presence of high velocity air  
     
     
         25 . The process of  claim 12 , wherein said exposing step comprises exposing said coated substrate to electron beam radiation.  
     
     
         26 . The process of  claim 12 , wherein said exposing step comprises exposing said coated substrate to ultraviolet radiation.  
     
     
         27 . The process of  claim 12 , further comprising the step of applying said composition comprising a radiation curable silicone release agent in an organic solvent to a second opposing surface of said substrate.