Brightness enhancing film comprising nanocomposite structure having improved crack resistance

Abstract

Microstructured films such as brightness enhancing films. The microstructured film has a polymerized structure comprising the reaction product of the polymerizable resin composition (e.g. having a refractive index of at least 1.58). The cured nanocomposite (e.g. structure) can exhibit improved crack resistance. In some embodiments, the flexibility is expressed in terms of a cylindrical mandrel bend test property (e.g. a mandrel size to failure of less than 6 mm or a mandrel size to failure according to the equation D=1000(T/0.025−T) wherein T is the thickness in millimeters of a (e.g. preformed base layer). In other embodiments, the flexibility is expressed in terms of a tensile and elongation property (e.g. a tensile strength at break of at least 25 MPa and an elongation at break of at least 1.75%).

What is claimed is: 
     
         1 . A brightness enhancing film having a polymerized structure comprising the reaction product of a polymerizable resin composition having a refractive index of at least 1.58 comprising, wherein the polymerizable resin composition comprises a) an organic component having at least one bisphenol ethoxylated di(meth)acrylate monomer and at least one monofunctional monomer selected from benzyl(meth)acrylate, phenylthio ethyl acrylate, and biphenyl(meth)acrylate monomers; and b) at least 10 wt-% of surface modified inorganic nanoparticles. 
     
     
         2 . The brightness enhancing film according to  claim 1  wherein the polymerizable resin composition has a refractive index of at least 1.61. 
     
     
         3 . The brightness enhancing film according to  claim 1  wherein the polymerizable resin composition has a refractive index of at least 1.645. 
     
     
         4 . The brightness enhancing film according to  claim 1  wherein one or more biphenyl monomers are present in an amount ranging from 25 wt-% to 75 wt-% of the organic component. 
     
     
         5 . The brightness enhancing film of  claim 1  wherein the biphenyl monomer has the formula: 
       
         
           
           
               
               
           
         
       
       wherein R1 is H or CH 3 ;
 X is O or S; 
 n ranges from 0 to 10; and 
 L is an alkyl group having 1 to 5 carbon atoms, optionally substituted with hydroxy. 
 
     
     
         6 . The brightness enhancing film of  claim 1  wherein the biphenyl monomer has the formula: 
       
         
           
           
               
               
           
         
       
       wherein R1 is H or CH 3 ;
 X is O or S; 
 Q is selected from —(C(CH 3 ) 2 —, —CH 2 , —C(O)—, —S(O)—, and —S(O) 2 —; 
 n ranges from 0 to 10; and 
 L is an alkyl group having 1 to 5 carbon atoms, optionally substituted with hydroxy. 
 
     
     
         7 . The brightness enhancing film of  claim 1  wherein the di(meth)acrylate aromatic monomer comprises a major portion having the structure 
       
         
           
           
               
               
           
         
         wherein R1 is independently hydrogen or methyl, 
         R2 is independently H or Br, 
         Z is independently —C(CH 3 ) 2 —, —CH 2 —, —C(O)—, —S—, —S(O)—, or —S(O) 2 —, and 
         L is a linking group independently selected from linear and branched C 2 -C 12  alkyl groups wherein the carbon chain is substituted with one or more oxygen group. 
       
     
     
         8 . The brightness enhancing film according to  claim 1  wherein the organic component further comprises up to 25 wt-% of one or more monofunctional (meth)acrylate monomers having a refractive index lower than the biphenyl monomer. 
     
     
         9 . The brightness enhancing film of  claim 1  wherein the polymerizable resin composition is free of silane surface treatments. 
     
     
         10 . The brightness enhancing film according to  claim 1  wherein the inorganic nanoparticles comprise a first surface treating agent having the formula:
   CH 3 [O—(CH 2 ) y ] x —X 2 —(CH 2 ) n —COOH
 
 
       wherein X 2  is selected from the group consisting of —O—, —S—, —C(O)O— and —C(O)NH; n ranges from 1-3; x ranges from 1-10; and y ranges from 1-4. 
     
     
         11 . The brightness enhancing film of  claim 10  wherein the first surface treating agent is selected from the group consisting of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, 2-(2-methoxyethoxy)acetic acid, succinic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, maleic acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, glutaric acid mono-[2-(2-methoxy-ethoxy)-ethyl]ester, succinic acid mono-2-[2-(2-methoxyethoxy)ethoxy]ethyl ester, and mixtures thereof. 
     
     
         12 . The brightness enhancing film according to  claim 10  wherein the inorganic nanoparticles comprise a second surface treating agent selected from the group consisting of succinic acid mono-(2-acryloyloxy-ethyl)ester, maleic acid mono-(2-acryloyloxy-ethyl)ester, glutaric acid mono-(2-acryloyloxy-ethyl)ester, maleic acid mono-(4-acryloyloxy-butyl)ester, succinic acid mono-(4-acryloyloxy-butyl)ester, and glutaric acid mono-(4-acryloyloxy-butyl)ester. 
     
     
         13 . The brightness enhancing film of  claim 1  wherein the amount of inorganic nanoparticles ranges from 40 wt-% to 60 wt-% of the polymerizable resin. 
     
     
         14 . The brightness enhancing film of  claim 1  wherein the inorganic nanoparticles are selected from the group consisting of zirconia, titania, and mixtures thereof. 
     
     
         15 . The brightness enhancing film of  claim 1  wherein the inorganic nanoparticle consist of zirconia. 
     
     
         16 . A brightness enhancing film having a polymerized structure comprising the reaction product of a polymerizable resin composition comprising an organic component having at least one bisphenol ethoxylated di(meth)acrylate monomer and at least one monofunctional monomer selected from benzyl(meth)acrylate, phenylthio ethyl acrylate, and biphenyl(meth)acrylate monomers. 
     
     
         17 . The brightness enhancing film of  claim 16  wherein the biphenyl monomer has the formula: 
       
         
           
           
               
               
           
         
       
       wherein R1 is H or CH 3 ;
 X is O or S; 
 n ranges from 0 to 10; and 
 L is an alkyl group having 1 to 5 carbon atoms, optionally substituted with hydroxy. 
 
     
     
         18 . The brightness enhancing film of  claim 16  wherein the biphenyl monomer has the formula: 
       
         
           
           
               
               
           
         
       
       wherein R1 is H or CH 3 ;
 X is O or S; 
 Q is selected from —(C(CH 3 ) 2 —, —CH 2 , —C(O)—, —S(O)—, and —S(O) 2 —; 
 n ranges from 0 to 10; and 
 L is an alkyl group having 1 to 5 carbon atoms, optionally substituted with hydroxy. 
 
     
     
         19 . The brightness enhancing film of  claim 16  wherein the di(meth)acrylate aromatic monomer comprises a major portion having the structure 
       
         
           
           
               
               
           
         
         wherein R1 is independently hydrogen or methyl, 
         R2 is independently H or Br, 
         Z is independently —C(CH 3 ) 2 —, —CH 2 —, —C(O)—, —S—, —S(O)—, or —S(O) 2 —, and 
         L is a linking group independently selected from linear and branched C 2 -C 12  alkyl groups wherein the carbon chain is substituted with one or more oxygen group. 
       
     
     
         20 . An optical film having a microstructured surface wherein the microstructured surface comprises the reaction product of a polymerizable resin composition comprising an organic component having at least one bisphenol ethoxylated di(meth)acrylate monomer and at least one monofunctional monomer selected from benzyl(meth)acrylate, phenylthio ethyl acrylate, and biphenyl(meth)acrylate monomers.