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 optical film, comprising the steps of:
 a) applying and drying a liquid crystal compound solution comprising a polymeric liquid crystal compound, a photoinitiator, and an organic solvent on a liquid crystal alignment layer that is formed by using a composition for liquid crystal alignment layer, and   b) irradiating UV rays on the formed liquid crystal layer to form a liquid crystal film.   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 of optical film according to  claim 24 , wherein the 1) photoreactive polymer has a number average molecular weight of 10,000˜500,000. 
     
     
         26 . The preparation method of optical film 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 of optical film 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 of optical film 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 of optical film 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 of optical film 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 of optical film 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-hexandiol di(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 of optical film 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 of optical film 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 of optical film 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 of optical film according to  claim 24 , wherein the content of the polymeric liquid crystal compound of step a) is 5 to 70 parts by weight, based on 100 parts by weight of the total liquid crystal compound solution, and the content of the photoinitiator is 3 to 10 parts by weight, based on 100 parts by weight of the polymeric liquid crystal compound, in the total liquid crystal compound solution. 
     
     
         36 . The preparation method of optical film according to  claim 24 , wherein the solvent in the liquid crystal compound of step a) includes one or more selected from the group consisting of halogenated hydrocarbons, aromatic hydrocarbons, ketones, alcohols, and cello solves.