Transparent double-sided self-adhesive sheet

Abstract

A transparent double-sided self-adhesive sheet is provided which, when bonding to an adhered, not only excels in the ability to conform to steps or surface irregularities caused by a printing site, but also excels in workability such as cutting processability. A transparent double-sided self-adhesive sheet is proposed, having an intermediate resin layer (A) and pressure-sensitive adhesive layers (B) as front and reverse side layers, each of the layers being a layer having one or more species of (meth)acrylic acid ester series (co)polymer as the base resin, in which transparent double-sided self-adhesive sheet, the shear storage elastic modulus (G′(A)) at a frequency of 1 Hz of the intermediate resin layer (A) is higher than the pressure-sensitive adhesive layers (B) in a temperature range of 0° C. to 100° C., and, the indentation hardness (ASKER C2 hardness) of the entire sheet is 10 to 80.

1 . A transparent double-sided self-adhesive sheet comprising a (meth)acrylic acid ester (co)polymer as a base resin, the sheet having an indentation hardness (ASKER C2 hardness) of 10 to 80, and having a creep of 1 mm to 15 mm,
 wherein the creep is assayed by   a) adhering one side of the sheet to a vertically standing SUS plate wherein an adhesion surface area is 15 mm×20 mm,   b) curing the sheet under an atmosphere of 60° C. for 15 minutes,   c) applying a weight of 4.9 N to the sheet in the vertical direction, and then   d) measuring the creep of the adhesion position at the end of 60 minutes.   
     
     
         2 . The sheet of  claim 1 , wherein the base resin comprises an acrylic acid ester (co)polymer comprising a randomly copolymerized monomer composition, the composition comprising a first monomer and a second monomer, wherein a homopolymer of the first monomer has a first glass transition temperature and a homopolymer of the second monomer has a second glass transition temperature, and the first and second glass transition temperatures differ by 25 to 300° C. 
     
     
         3 . The sheet of  claim 1 , wherein the sheet is suitable for bonding two image display device structural members into one body. 
     
     
         4 - 13 . (canceled) 
     
     
         14 . The sheet of  claim 2 , wherein the sheet is suitable for bonding two image display device structural members into one body. 
     
     
         15 . The sheet of  claim 3 , wherein the two image display device structural members are (I) a protective panel and a touch panel, (II) a touch panel and a liquid crystal panel, or (III) a protective panel and a liquid crystal panel. 
     
     
         16 . The sheet of  claim 14 , wherein the two image display device structural members are (I) a protective panel and a touch panel, (II) a touch panel and a liquid crystal panel, or (III) a protective panel and a liquid crystal panel. 
     
     
         17 . The sheet of  claim 1 , comprising a single layer sheet. 
     
     
         18 . The sheet of  claim 2 , comprising a single layer sheet. 
     
     
         19 . The sheet of  claim 1 , comprising two or more layers, each layer comprising a (meth)acrylic acid ester (co)polymer as a base resin, wherein:
 (i) the layers have nonidentical viscoelastic behaviors,   (ii) each layer is either (A) an intermediate layer or (B) a surface layer,   (iii) a shear storage elastic modulus at a frequency of 1 Hz of each intermediate layer (A) is greater than a shear storage elastic modulus of any surface layer (B) in the entire temperature range of 0° C. to 100° C., and   (iv) the indentation hardness (ASKER C2 hardness) of the entire sheet is 10 to 80.   
     
     
         20 . The sheet of  claim 19 , comprising one intermediate layer (A) and two pressure-sensitive adhesive surface layers (B), wherein the intermediate layer lies between the two surface layers. 
     
     
         21 . The sheet of  claim 20 , wherein the indentation hardness (ASKER C2 hardness) of the entire sheet is 10 to 60. 
     
     
         22 . The sheet of  claim 19 , wherein the indentation hardness (ASKER C2 hardness) of the entire sheet is 25 to 80. 
     
     
         23 . The sheet of  claim 20 , wherein the indentation hardness (ASKER C2 hardness) of the entire sheet is 25 to 80. 
     
     
         24 . The sheet of  claim 20 , wherein a thickness ratio between the intermediate layer (A) and each pressure-sensitive adhesive surface layer (B) is 0.5<(A)/(B)<10, and a thickness of the pressure-sensitive adhesive surface layer (B) is 10 μm to 200 μm. 
     
     
         25 . The sheet of  claim 21 , wherein a thickness ratio between the intermediate layer (A) and each pressure-sensitive adhesive surface layer (B) is 0.5<(A)/(B)<10, and a thickness of the pressure-sensitive adhesive surface layer (B) is 10 μm to 200 μm. 
     
     
         26 . The sheet of  claim 20 , wherein the value of Tan δ (B) for each pressure-sensitive adhesive surface layer (B) is 0.4 to 1.4 in a temperature range of 0° C. to 100° C. 
     
     
         27 . The sheet of  claim 21 , wherein a value of Tan δ (B) for each pressure-sensitive adhesive surface layer (B) is 0.4 to 1.4 in a temperature range of 0° C. to 100° C. 
     
     
         28 . The sheet of  claim 20 , wherein the shear storage elastic modulus (G′) of the intermediate layer (A) is 5×10 3  to 5×10 8  Pa in a temperature range of 0° C. to 100° C., and wherein the relationship between the shear storage elastic modulus (G′(A)) of the intermediate layer (A) and the shear storage elastic modulus (G′(B)) of the pressure-sensitive adhesive surface layer (B) in a temperature range of 0° C. to 100° C. is:
   1.1 <G ′( A )/ G ′( B )<80.
 
 
     
     
         29 . An integrated image display device comprising the sheet of  claim 1 . 
     
     
         30 . An integrated image display device comprising the sheet of claim  claim 19 .