# US 2013/0251990 A1 · Pressure-sensitive adhesive, pressure-sensitive adhesive layer, and pressure-sensitive adhesive sheet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0251990 A1 - Document ID: US20130251990A1 - Status: Published application - Kind: A1 - Application number: 13/847,843 - Filed: 2013-03-20 - Published: 2013-09-26 - Earliest claimed: 2012-03-21 - Assignees: Nitto Denko Corporation - Applicants: Nitto Denko Corporation - Inventors: Masatsugu HIGASHI; Koji SHITARA; Akiko TANAKA; Katsuhiko KAMIYA - Web page: https://patentgrep.com/patent/US20130251990A1 ## CPC - C09J 133/14: of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen - C09J 7/385: {Acrylic polymers} - C09J 133/066: {containing -OH groups} - C09J 133/10: Homopolymers or copolymers of methacrylic acid esters - C09J 2203/318: for the production of liquid crystal displays - Y10T 428/2891: including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof - 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) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A pressure-sensitive adhesive of the invention includes a (meth)acryl-based polymer obtained by polymerization of a monomer component including: an alkyl(meth)acrylate (a1) having a branched alkyl group of 8 to 24 carbon atoms at an ester end; and an alkyl(meth)acrylate (a2) having a linear alkyl group of 8 to 24 carbon atoms at an ester end. The pressure-sensitive adhesive can has a satisfactory level of adhesive performance and can form a pressure-sensitive adhesive layer with a lower dielectric constant. ## Claims ### Claim 1 A pressure-sensitive adhesive, comprising a (meth)acryl-based polymer obtained by polymerization of a monomer component including: an alkyl(meth)acrylate (a1) having a branched alkyl group of 8 to 24 carbon atoms at an ester end; and an alkyl(meth)acrylate (a2) having a linear alkyl group of 8 to 24 carbon atoms at an ester end. ### Claim 2 (depends on 1) The pressure-sensitive adhesive according to claim 1, wherein the total content of the alkyl(meth)acrylate (a1) having a branched alkyl group of 8 to 24 carbon atoms at an ester end and the alkyl(meth)acrylate (a2) having a linear alkyl group of 8 to 24 carbon atoms at an ester end in the monomer component is from 35 to 99.5% by weight. ### Claim 3 (depends on 1) The pressure-sensitive adhesive according to claim 1, wherein the alkyl(meth)acrylate (a2) having a linear alkyl group at an ester end is capable of forming a homopolymer with a Tg of −20° C. or lower. ### Claim 4 (depends on 1) The pressure-sensitive adhesive according to claim 1, wherein the monomer component further include at least one functional group-containing monomer selected from a carboxyl group-containing monomer, a hydroxyl group-containing monomer, and a cyclic ether group-containing monomer. ### Claim 5 (depends on 1) The pressure-sensitive adhesive according to claim 1, wherein the alkyl(meth)acrylate (a2) having a linear alkyl group at an ester end is an alkyl methacrylate having a linear alkyl group at an ester end. ### Claim 6 (depends on 1) The pressure-sensitive adhesive according to claim 1, wherein the monomer component further include a monomer capable of forming a homopolymer with a Tg of 0° C. or higher, which is other than the monomer (a1), the monomer (a2), the carboxyl group-containing monomer, the hydroxyl group-containing monomer, and the cyclic ether group-containing monomer. ### Claim 7 (depends on 6) The pressure-sensitive adhesive according to claim 6, wherein the monomer capable of forming a homopolymer with a Tg of 0° C. or higher has a cyclic structure. ### Claim 8 (depends on 7) The pressure-sensitive adhesive according to claim 7, wherein the monomer capable of forming a homopolymer with a Tg of 0° C. or higher is a cyclic nitrogen-containing monomer. ### Claim 9 (depends on 1) The pressure-sensitive adhesive according to claim 1, further comprising 0.01 to 5 parts by weight of a crosslinking agent based on 100 parts by weight of the (meth)acryl-based polymer. ### Claim 10 (depends on 9) The pressure-sensitive adhesive according to claim 9, wherein the crosslinking agent is an isocyanate crosslinking agent. ### Claim 11 (depends on 1) The pressure-sensitive adhesive according to claim 1, further comprising a silane coupling agent. ### Claim 12 (depends on 1) The pressure-sensitive adhesive according to claim 1, which is for use on an optical member. ### Claim 13 (depends on 1) A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive according to claim 1. ### Claim 14 (depends on 13) The pressure-sensitive adhesive layer according to claim 13, which has a gel fraction of 20 to 98% by weight. ### Claim 15 (depends on 13) The pressure-sensitive adhesive layer according to claim 13, which has a relative dielectric constant of 3.5 or less at a frequency of 100 kHz. ### Claim 16 (depends on 13) The pressure-sensitive adhesive layer according to claim 13, which has a haze of 2% or less when having a thickness of 50 μm. ### Claim 17 (depends on 13) The pressure-sensitive adhesive layer according to claim 13, which has a total light transmittance of 90% or more. ### Claim 18 (depends on 13) The pressure-sensitive adhesive layer according to claim 13, which is for use on an optical member. ### Claim 19 (depends on 13) A pressure-sensitive adhesive sheet, comprising: a support; and the pressure-sensitive adhesive layer according to claim 13 formed on at least one side of the support. ### Claim 20 (depends on 19) The pressure-sensitive adhesive sheet according to claim 19, which has an adhesive strength of 8 N/20 mm or more to alkali glass at a peel angle of 90° and a peel rate of 300 mm/minute when the pressure-sensitive adhesive layer has a thickness of 50 μm. ### Claim 21 (depends on 19) The pressure-sensitive adhesive sheet according to claim 19, which is for use on an optical member. ### Claim 22 (depends on 19) The pressure-sensitive adhesive sheet according to claim 19, which is a pressure-sensitive adhesive optical member comprising an optical member as the support and the pressure-sensitive adhesive layer provided on at least one side of the optical member.