Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet

Patent metadata

Field	Value
Publication number	US-2019106608-A1
Application number	US-201816152776-A
Country	US
Kind code	A1
Filing date	Oct 5, 2018
Priority date	Oct 6, 2017
Publication date	Apr 11, 2019
Grant date	—

Abstract

The present invention provides an acrylic PSA composition. The acrylic PSA composition comprises an acrylic polymer as its base polymer and at least one species selected among tackifier resins and (meth)acrylic oligomers. The acrylic polymer has a weight average molecular weight higher than 70×104. The acrylic polymer has a dispersity (Mw/Mn) below 15.

First claim

What is claimed is:

1 . An acrylic pressure-sensitive adhesive composition comprising an acrylic polymer as its base polymer and at least one species selected among tackifier resins and (meth)acrylic oligomers, wherein
the acrylic polymer has a weight average molecular weight higher than 70×10 4 , and the acrylic polymer has a dispersity (Mw/Mn) below 15.

2 . The acrylic pressure-sensitive adhesive composition according to claim 1 , wherein the acrylic polymer includes at least 50% (by weight) alkyl (meth)acrylate having an alkyl group with 1 up to 6 carbon atoms at its ester terminus polymerized therein.

3 . The acrylic pressure-sensitive adhesive composition according to claim 1 , wherein the acrylic polymer includes an acidic group-containing monomer copolymerized therein.

4 . The acrylic pressure-sensitive adhesive composition according to claim 3 , wherein the acidic group-containing monomer in the acrylic polymer has a copolymerization ratio lower than 10% by weight.

5 . The acrylic pressure-sensitive adhesive composition according to claim 1 , wherein the tackifier resin is included at a ratio lower than 30 parts by weight relative to 100 parts by weight of the acrylic polymer.

6 . The acrylic pressure-sensitive adhesive composition according to claim 1 , wherein the (meth)acrylic oligomer is included at a ratio lower than 30 parts by weight relative to 100 parts by weight of the acrylic polymer.

7 . The acrylic pressure-sensitive adhesive composition according to claim 1 , including both the tackifier resin and the (meth)acrylic oligomer.

8 . A pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer that comprises an acrylic polymer as its base polymer and at least one species selected among tackifier resins and (meth)acrylic oligomers, wherein
the acrylic polymer has a weight average molecular weight higher than 70×10 4 , and the acrylic polymer has a dispersity (Mw/Mn) below 15.

9 . A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer, wherein
the pressure-sensitive adhesive layer has a storage modulus at 25° C., G′(25° C.), of 0.15 MPa or greater and a storage modulus at 85° C., G′(85° C.), of 0.02 MPa or greater; and the pressure-sensitive adhesive sheet satisfies at least one of the following features: having a 180° peel strength of 8 N/20 mm or greater when determined within one minute after press-bonded at 23° C. at a press-bonding load of 0.1 kg or a 180° peel strength of 8 N/20 mm or greater when determined within one minute after press-bonded at 40° C. at 0.05 MPa for 3 seconds.

10 . The pressure-sensitive adhesive sheet according to claim 8 , wherein the pressure-sensitive adhesive layer has a gel fraction of 40% by weight or higher.

11 . The pressure-sensitive adhesive sheet according to claim 9 , wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer comprising an acrylic polymer.

12 . The pressure-sensitive adhesive sheet according to claim 8 , wherein the acrylic polymer includes at least 50% (by weight) alkyl (meth)acrylate copolymerized therein, with the alkyl (meth)acrylate having an alkyl group with 1 up to 6 carbon atoms at its ester terminus.

13 . The pressure-sensitive adhesive sheet according to claim 8 , wherein the acrylic polymer includes an acidic group-containing monomer copolymerized therein.

14 . The pressure-sensitive adhesive sheet according to claim 13 , wherein the acidic group-containing monomer is acrylic acid.

15 . The pressure-sensitive adhesive sheet according to claim 13 , wherein the acidic group-containing monomer has a copolymerization ratio below 10% by weight in the acrylic polymer.

16 . The pressure-sensitive adhesive sheet according to claim 8 , wherein the acrylic polymer is crosslinked.

17 . The pressure-sensitive adhesive sheet according to claim 8 , used for fixing parts in mobile electronics.

18 . The pressure-sensitive adhesive sheet according to claim 8 , used for fixing a flexible printed circuit.

Assignees

• Nitto Denko Corp

Inventors

• Jozuka Kenta
• Higuchi Naoaki
• Furuta Kenji
• Kato Naohiro
• Buzojima Yasushi

Classifications

• C09J2203/326

  for bonding electronic components such as wafers, chips or semiconductors · CPC title

• C09J2433/00

  Presence of (meth)acrylic polymer · CPC title

• C09J7/10

  without carriers · CPC title

• C09J133/12

  Homopolymers or copolymers of methyl methacrylate · CPC title

• C09J133/10

  Homopolymers or copolymers of methacrylic acid esters · CPC title