# US 8,568,873 B2 · Pressure-sensitive adhesive for polarizing plates, polarizing plate with pressure-sensitive adhesive and production process for the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,568,873 B2 - Document ID: US8568873B2 - Status: Granted - Kind: B2 - Application number: 11/608,024 - Filed: 2006-12-07 - Published: 2007-06-28 - Granted: 2013-10-29 - Earliest claimed: 2005-12-26 - Assignees: Lintec Corporation - Applicants: Kentaro Kusama; Koichi Nagamoto; Mikihiro Kashio; Kazuhiro Kon; Motoyuki Hayakawa - Inventors: Kentaro Kusama; Koichi Nagamoto; Mikihiro Kashio; Kazuhiro Kon; Motoyuki Hayakawa - Web page: https://patentgrep.com/patent/US8568873B2 ## CPC - C09J 133/08: Homopolymers or copolymers of acrylic acid esters - G02B 5/3016: {involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528)} - Y10T 428/14: Layer or component removable to expose adhesive - Y10T 428/1476: Release layer - Y10T 428/28: Web or sheet containing structurally defined element or component and having an adhesive outermost layer - Y10T 428/2809: including irradiated or wave energy treated component - Y10T 428/2852: Adhesive compositions - Y10T 428/2878: including addition polymer from unsaturated monomer - Y10T 428/2887: including nitrogen containing polymer [e.g., polyacrylonitrile, polymethacrylonitrile, etc.] - Y10T 428/2891: including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof - Y10T 428/31928: Ester, halide or nitrile of addition polymer - C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Provided are a pressure-sensitive adhesive for polarizing plates which can apply a polarizing plate on a liquid crystal cell with good adhesion and has the characteristic that a liquid crystal display device obtained therefrom is less liable to cause light leakage even under the environment of high temperature and high humidity and which has a removability and a polarizing plate with the above pressure-sensitive adhesive and a production process for the same. The pressure-sensitive adhesive for polarizing plates is prepared by irradiating a pressure-sensitive adhesive material comprising (A) an acrylic base polymer comprising a monomer having a carboxyl group in a monomer composition ratio of 0.5 mass % or less and (B) an active energy beam-curable compound with an active energy beam and it has a storage elastic modulus (G′) of 0.3 MPa or more at 23° C. ## Claims ### Claim 1 A pressure-sensitive adhesive for polarizing plates, which is prepared by irradiating a pressure-sensitive adhesive material comprising (A) an acrylic base polymer comprising a structural unit obtained from a monomer having a carboxyl group in a monomer composition ratio of 0.5 mass % or less and (B) an active energy beam-curable compound, wherein the active energy beam-curable compound is a multifunctional (meth)acrylate base monomer having a cyclic structure, and a photopolymerization initiator, with an active energy beam and wherein the pressure-sensitive adhesive has a storage elastic modulus (G′) of 0.3 MPa or more at 23° C., wherein the ratio (A)/(B) is in a range from 100:10 to 100:50 by mass ratio, and (A) is a polymer consisting of units from at least one monomer selected from the group consisting of methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, pentyl(meth)acrylate, hexyl(meth)acrylate, cyclohexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isooctyl(meth)acrylate, decyl(meth)acrylate, dodecyl(meth)acrylate, myristyl(meth)acrylate, palmityl(meth)acrylate, stearyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 3-hydroxybutyl(meth)acrylate and 4-hydroxybutyl(meth)acrylate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide and N-methylolmethacrylamide, monomethylaminoethyl(meth)acrylate, monoethylaminoethyl(meth)acrylate, monomethylaminopropyl(meth)acrylate and monoethylaminopropyl(meth)acrylate, and optionally one or more monomers selected from the group consisting of (meth)acrylic acid, crotonic acid, maleic acid, and itaconic acid. ### Claim 2 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein the storage elastic modulus (G′) at 23° C. is 0.3 to 15 MPa. ### Claim 3 (depends on 1, 2) The pressure-sensitive adhesive for polarizing plates as described in claim 1 or 2, wherein the storage elastic modulus (G′) at 80° C. is 0.3 MPa or more. ### Claim 4 (depends on 3) The pressure-sensitive adhesive for polarizing plates as described in claim 3, wherein the storage elastic modulus (G′) at 80° C. is 0.3 to 10 MPa. ### Claim 5 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein it is used for applying a polarizing plate on a liquid crystal glass cell. ### Claim 6 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein the multifunctional (meth)acrylate base monomer having a cyclic structure has a molecular weight of less than 1000. ### Claim 7 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein the pressure-sensitive adhesive material further comprises (C) a cross-linking agent. ### Claim 8 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein the pressure-sensitive adhesive material further comprises (D) a silane coupling agent. ### Claim 9 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein an adhesive strength to non-alkali glass is 0.2 to 20 N/25 mm. ### Claim 10 (depends on 9) The pressure-sensitive adhesive for polarizing plates as described in claim 9, wherein a rise percentage of the adhesive strength to non-alkali glass after 168 hours pass since applied is 20% or less based on the initial value. ### Claim 11 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein a maximum shear load at a distortion of 4000% or less in applying the polarizing plate on non-alkali glass at an applying area of 100 mm2 (10 mm×10 mm) and measuring a shear load at a shearing rate of 0.1 mm/minute is 70 N or less. ### Claim 12 (depends on 1) The pressure-sensitive adhesive for polarizing plates as described in claim 1, wherein a gel ratio is 85% or more. ### Claim 13 (depends on 1) A polarizing plate with a pressure-sensitive adhesive, characterized by having a layer comprising the pressure-sensitive adhesive as described in claim 1 on a polarizing plate. ### Claim 14 (depends on 13) A production process for the polarizing plate with the pressure-sensitive adhesive as described in claim 13, comprising applying a polarizing plate on a pressure-sensitive adhesive material layer provided on a release layer of a release sheet and then irradiating a release sheet side with an active energy beam. ### Claim 15 (depends on 1) A pressure-sensitive adhesive sheet prepared by interposing the pressure-sensitive adhesive for polarizing plates as described in claim 1 between two release sheets so that the pressure-sensitive adhesive is brought into contact with release layer sides of the release sheets.