Composition for liquid crystal alignment layer, preparation method of liquid crystal alignment layer using the same, and optical film comprising the liquid crystal alignment layer

Abstract

The present invention relates to a composition for liquid crystal alignment layer, a preparation method of liquid crystal alignment layer using the same, and an optical film comprising the liquid crystal alignment layer. More particularly, the composition for liquid crystal alignment layer according to the present invention includes crosslinkable functional monomers as well as a photoreactive polymer, thereby improving thermal stability and durability of the liquid crystal alignment layer that is prepared by using the composition for liquid crystal alignment layer. In addition, when the liquid crystal alignment layer is used to produce an optical film, adhesive strength between substrate and liquid crystal alignment layer and between liquid crystal alignment layer and liquid crystal film can be improved.

1 - 23 . (canceled) 
     
     
         24 . A preparation method of liquid crystal alignment layer, comprising the steps of:
 a) applying and drying a composition for liquid crystal alignment layer on a substrate to form a coating, and   b) irradiating UV rays onto the coating formed on the substrate.   wherein the composition for liquid crystal alignment layer, comprising   1) one or more photoreactive polymer selected from the group consisting of a norbornene-based photoreactive polymer comprising a cinnamate group and a photoreactive polymer comprising an unit represented by the following Formula 1,   2) a multifunctional monomer crosslinkable with the 1) photoreactive polymer,   3) a photoinitiator, and   4) an organic solvent:   
       
         
           
           
               
               
           
         
       
     
     
         25 . The preparation method according to  claim 24 , wherein the 1) photoreactive polymer has a number average molecular weight of 10,000˜500,000. 
     
     
         26 . The preparation method according to  claim 24 , wherein the norbornene-based photoreactive polymer comprising a cinnamate group comprises a unit represented the following Formula 3: 
       
         
           
           
               
               
           
         
         wherein n is 50 to 5,000, 
         at least one of R1 and R2 is represented by the following Formula 4, and 
         the other is selected from the group consisting of a hydrogen, a halogen, an alkyl group having 1 to 20 carbon atoms, and a group represented by the following Formula 4, 
       
       
         
           
           
               
               
           
         
       
       wherein R3 is each independently selected from the group consisting of a hydrogen, a halogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an allyloxy group. 
     
     
         27 . The preparation method according to  claim 24 , wherein the norbornene-based photoreactive polymer comprising a cinnamate group comprises one or more selected from the group consisting of polynorbornene cinnamate, polynorbornene alkoxycinnamate (alkoxy group having 1 to 20 carbon atoms), polynorbornene allyloyloxycinnamate, polynorbornene fluorinatedcinnamate, and polynorbornene dicinnamate. 
     
     
         28 . The preparation method according to  claim 24 , wherein the norbornene-based photoreactive polymer comprising a cinnamate group comprises one or more selected from the units represented by the following Formulae 5 to 10: 
       
         
           
           
               
               
           
         
       
       wherein n is 50 to 5,000. 
     
     
         29 . The preparation method according to  claim 24 , wherein the content of the 1) photoreactive polymer is 0.1 to 20% by weight, based on the total composition for liquid crystal alignment layer. 
     
     
         30 . The preparation method according to  claim 24 , wherein the 2) multifunctional monomer comprises a functional group that generates a radical reaction selected from the group consisting of the following Structural Formulae: 
       
         
           
           
               
               
           
         
       
     
     
         31 . The preparation method according to  claim 24 , wherein the 2) multifunctional monomer comprises one or more selected from the group consisting of trimethylolpropane triacrylate, pentaerythritol tri(meth)/tetraacrylate, dipentaerythritol hexa/pentaacrylate, triglycerol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, 1,6-hexandioldi(meth)acrylate, glycerol di(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, methoxyethyl(meth)acrylate, N,N-dimethylaminoethyl(methyl)acrylate, butoxytriethylene glycol(meth)acrylate, 2-carboxyethyl acrylate, hydroxypropyl acrylate, mono-2-(acryloyloxy)ethyl succinate, vinyl acrylate, 3-(acryloyloxy)-2-hydroxypropyl(meth)acrylate, glycerol 1,3-diglycerolate diacrylate, tri(propylene glycol)glycerolate diacrylate, allyl(meth)acrylate, diacetone acrylamide, (meth)acrylamide, methyl 2-acetamidoacrylate, N-[tris(hydroxymethyl)methyl]acrylamide, N,N′-(1,2-dihydroxyethylene)bisacrylamide, N,N′-methylenebis(acrylamide), 1,3,5-triacryloylhexahydro-1,3,5-triazine, 2,4,6-triallyloxy-1,3,5-triazine, tris(2,3-epoxypropyl)isocyanurate, tris[2-(acryloyloxy)ethyl]isocyanurate, tetracyanoethylene oxide, triallyl 1,3,5-benzenetricarboxylate, diacetone acrylamide, N,N′-(1,2-dihydroxyethylene)bisacrylamide, poly(melamine-co-formaldehyde), 2-carboxyethyl acrylate, hydroxypropyl acrylate, mono-2-(acryloyloxy)ethyl succinate, vinyl acrylate, 3-(acryloyloxy)-2-hydroxypropyl(meth)acrylate, 2-(2-oxo-imidazolydinyl)ethyl(meth)acrylate, caprolactone 2-((meth)acryloyloxy)ethyl ester, mono-2-((meth)acryloyloxy)ethyl malate, 1,2,3-triazol-4,5-dicarboxylic acid, 3-allyloxy-1,2-propandiol, bis[4-(glycidyloxy)phenyl]methane, and 2-vinyl-1,3,-dioxalene. 
     
     
         32 . The preparation method according to  claim 24 , wherein the content of the 2) multifunctional monomer is 0.1 to 20% by weight, based on the total composition for liquid crystal alignment layer. 
     
     
         33 . The preparation method according to  claim 24 , wherein the content of the 3) photoinitiator is 0.01 to 5% by weight, based on the total composition for liquid crystal alignment layer. 
     
     
         34 . The preparation method according to  claim 24 , wherein the 4) organic solvent includes one or more selected from the group consisting of ether-based, aromatic-based, halogen-based, olefin-based, and ketone-based solvents. 
     
     
         35 . The preparation method according to  claim 24 , wherein the coating formed in step a) has a thickness of 800 to 2,000 Å. 
     
     
         36 . The preparation method according to  claim 24 , wherein the substrate of step a) is a glass or plastic substrate. 
     
     
         37 . An optical film comprising the liquid crystal alignment layer prepared by the preparation method of liquid crystal alignment layer according to  claim 24  and a polymeric liquid crystal compound. 
     
     
         38 . The optical film according to  claim 37 , wherein the polymeric liquid crystal compound includes one or more selected from substances having an acrylate group being polymerizable by photoreaction. 
     
     
         39 . The optical film according to  claim 38 , wherein the substance having an acrylate group is selected from the group consisting of cianobiphenyl-based acrylate, cianophenyl cyclohexane-based acrylate, cianophenyl ester-based acrylate, benzoic acid phenyl ester-based acrylate, phenyl pyrimidine-based acrylate, and mixtures thereof. 
     
     
         40 . A liquid crystal display device comprising one or more optical films according to  claim 37 . 
     
     
         41 . An integrated polarizing plate, comprising a polarizing film and one or more optical films of  claim 37  on one side or both sides of the polarizing film as a protective film. 
     
     
         42 . A liquid crystal display device comprising the integrated polarizing plate of  claim 41 .