Optical member, pressure-sensitive adhesive composition and liquid crystal display

Abstract

Provided are an optical member, a pressure-sensitive adhesive composition, and an LCD. The optical member may have excellent endurance reliability even when a pressure-sensitive adhesive layer is formed to have a thickness of 20 μm or less.

What is claimed is: 
     
         1 . An optical member, comprising:
 a base layer; and   a pressure-sensitive adhesive layer which includes an acryl polymer having polymerization units derived from a first (meth)acrylic acid ester monomer capable of forming a homopolymer having a glass transition temperature of less than 0° C., a crosslinkable monomer including a crosslinkable functional group except an acid functional group, and a second (meth)acrylic acid ester monomer capable of forming a homopolymer having a glass transition temperature of 0° C. to 100° C., which is formed on one or both surfaces of the base layer, and which has a thickness of 20 μm or less.   
     
     
         2 . The optical member according to  claim 1 , wherein the base layer is a polarizer, a polarizing plate, a retardation plate, a viewing angle retardation film or a brightness-enhancing film. 
     
     
         3 . The optical member according to  claim 1 , wherein the acryl polymer has an acid value of 10 or less. 
     
     
         4 . The optical member according to  claim 1 , wherein the first (meth)acrylic acid ester monomer is an alkyl (meth)acrylate capable of forming a homopolymer having a glass transition temperature of −70° C. to −30° C. 
     
     
         5 . The optical member according to  claim 1 , wherein the second (meth)acrylic acid ester monomer is an alkyl (meth)acrylate capable of forming a homopolymer having a glass transition temperature of 0° C. to 60° C. 
     
     
         6 . The optical member according to  claim 1 , wherein the second (meth)acrylic acid ester monomer is an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 6 carbon atoms. 
     
     
         7 . The optical member according to  claim 1 , wherein the second (meth)acrylic acid ester monomer is methyl acrylate or t-butyl acrylate. 
     
     
         8 . The optical member according to  claim 1 , wherein the acryl polymer has a polymerization unit derived from 1 to 1000 parts by weight of the first (meth)acrylic acid ester monomer with respect to 100 parts by weight of the second (meth)acrylic acid ester monomer. 
     
     
         9 . The optical member according to  claim 1 , wherein the acryl polymer has a polymerization unit derived from 125 to 900 parts by weight of the first (meth)acrylic acid ester monomer with respect to 100 parts by weight of the second (meth)acrylic acid ester monomer. 
     
     
         10 . The optical member according to  claim 1 , wherein the crosslinkable functional group except an acid functional group is at least one selected from the group consisting of a hydroxyl group, a glycidyl group, an isocyanate group and a nitrogen-containing functional group. 
     
     
         11 . The optical member according to  claim 1 , wherein the acryl polymer has a weight average molecular weight of 500,000 to 2,000,000. 
     
     
         12 . The optical member according to  claim 1 , wherein the pressure-sensitive adhesive layer has a dynamic storage modulus of 0.05 to 0.08 MPa at 30° C. and a frequency of 500 Hz. 
     
     
         13 . The optical member according to  claim 1 , wherein the pressure-sensitive adhesive layer has a glass transition temperature of −50° C. to 0° C. 
     
     
         14 . The optical member according to  claim 1 , wherein the pressure-sensitive adhesive layer has a thickness of 15 μm or less. 
     
     
         15 . A pressure-sensitive adhesive composition, comprising:
 an acryl polymer having a polymerization unit derived from a first (meth)acrylic acid ester monomer capable of forming a homopolymer having a glass transition temperature of less than 0° C., a crosslinkable monomer including a crosslinkable functional group except an acid functional group, and a second (meth)acrylic acid ester monomer capable of forming a homopolymer having a glass transition temperature of 0° C. to 100° C.   
     
     
         16 . The composition according to  claim 15 , which is used to form the pressure-sensitive adhesive layer included in the optical member of  claim 1 . 
     
     
         17 . The composition according to  claim 15 , wherein the acryl polymer has an acid value of 10 or less. 
     
     
         18 . The composition according to  claim 15 , wherein the acryl polymer has a polymerization unit derived from 1 to 1000 parts by weight of the first (meth)acrylic acid ester monomer with respect to 100 parts by weight of the second (meth)acrylic acid ester monomer. 
     
     
         19 . The composition according to  claim 15 , wherein the acryl polymer has a polymerization unit derived from 125 to 900 parts by weight of the first (meth)acrylic acid ester monomer with respect to 100 parts by weight of the second (meth)acrylic acid ester monomer. 
     
     
         20 . A liquid crystal display, in which the optical member of  claim 1  is attached to a liquid crystal panel by a pressure-sensitive adhesive layer of the optical member.