Thin microstructured optical films

Abstract

Presently described are optical films, such as a brightness enhancing film, having a polymerized microstructured surface disposed on a preformed polymeric film wherein the film has a thickness of no greater than 3 mils and the polymerized microstructured surface consists of the reaction product of a substantially non-brominated polymerizable resin composition.

What is claimed is: 
     
         1 . A brightness enhancing film having a polymerized microstructured surface disposed on a preformed polymeric film wherein the preformed polymeric film has a thickness of less than or equal to 3 mils and the polymerized microstructured surface consists of the reaction product of a non-brominated polymerizable resin composition comprising i) at least about 60 wt-% of one or more bisphenol di(meth)acrylate monomers, aromatic epoxy di(meth)acrylate oligomers, or mixtures thereof; comprising the general structure 
       
         
           
           
               
               
           
         
         wherein 
         Z is independently —C(CH 3 ) 2 — or —CH 2 —, 
         Q is independently O or S, 
         each R1 is independently hydrogen or methyl, 
         n is 2 to 10, and 
         L is C2. 
         ii) about 5 wt-% to about 40 wt-% of one or more aromatic monofunctional (meth)acrylate monomers having a viscosity less than 300 cps; 
         wherein the polymerizable composition comprises 0 to 15 wt-% of components comprising three or more (meth)acrylate groups; and the brightness enhancing film exhibits curl from 0 mm to less than 2 mm. 
       
     
     
         2 . The brightness enhancing film of  claim 1  wherein the non-brominated polymerizable resin comprises at least about 65 wt-% of the bisphenol di(meth)acrylate monomer, aromatic epoxy di(meth)acrylate oligomers, or a mixture thereof. 
     
     
         3 . The brightness enhancing film of  claim 1  wherein the non-brominated polymerizable resin comprises
 at least about 70 wt-% of the bisphenol di(meth)acrylate monomer, aromatic epoxy di(meth)acrylate oligomers, or a mixture thereof. 
 
     
     
         4 . The brightness enhancing film of  claim 1  wherein the non-brominated polymerizable composition is substantially free of (meth)acrylate monomer and oligomers that comprise three or more (meth)acrylate groups. 
     
     
         5 . The brightness enhancing film of  claim 1  wherein the one or more aromatic monofunctional (meth)acrylate monomers comprises an aromatic group selected from phenyl, biphenyl, cumyl, and napthyl. 
     
     
         6 . The brightness enhancing film of  claim 5  wherein the one or more aromatic monofunctional (meth)acrylate monomers comprises phenoxy ethyl acrylate, phenylthio ethyl acrylate, and mixtures thereof. 
     
     
         7 . The brightness enhancing film of  claim 5  wherein the one or more aromatic monofunctional (meth)acrylate monomers comprises 
       
         
           
           
               
               
           
         
         and mixtures thereof. 
       
     
     
         8 . The brightness enhancing film of  claim 7  wherein the one or more aromatic monofunctional (meth)acrylate monomers comprises 2-phenyl-phenyl acrylate, 2-phenyl-phenoxyethyl acrylate. 
     
     
         9 . The brightness enhancing film of  claim 5  wherein the one or more aromatic monofunctional (meth)acrylate monomers comprises benzyl acrylate. 
     
     
         10 . The brightness enhancing film of  claim 1  wherein the preformed polymeric film has a thickness of less than or equal to about 2 mils. 
     
     
         11 . The brightness enhancing film of  claim 1  wherein the preformed polymeric film has a thickness of less than or equal to about 1 mil. 
     
     
         12 . The brightness enhancing film of  claim 1  wherein the preformed polymeric film is PET. 
     
     
         13 . The brightness enhancing film of  claim 1  wherein the non-brominated polymerizable resin composition is non-halogenated. 
     
     
         14 . The brightness enhancing film of  claim 1  wherein the polymerized microstructured surface is a prismatic structure having a distance between prism peaks of between 10 and 35 microns, and a prism height of between 5 and 18 microns. 
     
     
         15 . An optical film having a polymerized microstructured surface disposed on a preformed polymeric film wherein the film has a thickness of less than or equal to 3 mils and the polymerized microstructured surface consists of the reaction product of a non-brominated polymerizable resin composition comprising
 i) at least about 60 wt-% of one or more bisphenol di(meth)acrylate monomers, aromatic epoxy di(meth)acrylate oligomers, or mixtures thereof; comprising the general structure   
       
         
           
           
               
               
           
         
         wherein 
         Z is independently —C(CH 3 ) 2 —or —CH 2 —, 
         Q is independently O or S, 
         each R1 is independently hydrogen or methyl, 
         n is 2 to 10, and 
         L is C2. 
         ii) about 5 wt-% to about 40 wt-% of one or more aromatic monofunctional (meth)acrylate monomers having a viscosity less than 300 cps; 
         wherein the polymerizable composition comprises 0 to 15 wt-% of components comprising three or more (meth)acrylate groups.