Adhesive sheet

Patent metadata

Field	Value
Publication number	US-10920108-B2
Application number	US-201515515191-A
Country	US
Kind code	B2
Filing date	Sep 28, 2015
Priority date	Sep 30, 2014
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

A pressure-sensitive adhesive sheet according to the present invention includes an irradiation-curable acrylic pressure-sensitive adhesive layer. The acrylic pressure-sensitive adhesive layer includes an acrylic polymer and a multifunctional acrylic oligomer. The acrylic pressure-sensitive adhesive layer, after curing, has a Young's modulus of 500 kPa to 10000 kPa at 23° C. The acrylic pressure-sensitive adhesive layer, after curing, has an adhesive strength of 3.0 N/20 mm or more. The acrylic pressure-sensitive adhesive layer before curing may have an adhesive strength of typically 3.0 N/20 mm or more. The acrylic pressure-sensitive adhesive layer before curing may have a Young's modulus of typically 30 kPa to 200 kPa at 23° C.

First claim

The invention claimed is:

1. A pressure-sensitive adhesive sheet comprising
an irradiation-curable, acrylic pressure-sensitive adhesive layer,
the acrylic pressure-sensitive adhesive layer comprising:
an acrylic polymer; and
a multifunctional acrylic oligomer,

the acrylic pressure-sensitive adhesive layer, after curing, having a Young's modulus of 500 kPa to 7,000 kPa at 23° C.,
the acrylic pressure-sensitive adhesive layer, after curing, having an adhesive strength of 3.0 N/20 mm or more,
wherein the adhesive strength is measured according to JIS Z 0237 using a stainless steel plate or a polycarbonate resin plate,
wherein the acrylic polymer is derived from monomer components comprising 13 to 30 mass percent of one or more hydroxy group-containing monomers, and
wherein the acrylic pressure-sensitive adhesive layer comprises 0.05 to less than 20 parts by mass of the multifunctional acrylic oligomer per 100 parts by mass of the acrylic polymer.

2. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer before curing has an adhesive strength of 3.0 N/20 mm or more.

3. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer before curing has a Young's modulus of 30 kPa to 200 kPa at 23° C.

4. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer, after curing, has a gel fraction of 70 mass percent or more.

5. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the monomer components comprise 0.5 to 30 mass percent of one or more nitrogen-containing monomers.

6. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the monomer components are substantially free from acidic-group-containing monomers.

7. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic polymer has a weight-average molecular weight of 40×10 4 to 200×10 4 .

8. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the multifunctional acrylic oligomer contains two or more (meth)acryloyl groups per molecule.

9. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the multifunctional acrylic oligomer comprises at least one substance selected from the group consisting of:
polyester (meth)acrylates;
epoxy (meth)acrylates;
urethane (meth)acrylates; and
bisphenol-A ethylene oxide adduct diacrylates.

10. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the multifunctional acrylic oligomer has a weight-average molecular weight of 400 to 10000.

11. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the multifunctional acrylic oligomer gives a homopolymer having a hardness of 4B or more as measured in conformity with JIS K 5600-5-4.

12. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer further comprises one or more photoinitiators.

13. The pressure-sensitive adhesive sheet according to claim 12 ,
wherein the acrylic pressure-sensitive adhesive layer further comprises:
0.05 to 5 parts by mass of the photoinitiator,
per 100 parts by mass of the acrylic polymer.

14. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer further comprises
0.05 to 5 parts by mass of one or more crosslinkers per 100 parts by mass of the acrylic polymer.

15. The pressure-sensitive adhesive sheet according to claim 1 ,
wherein the acrylic pressure-sensitive adhesive layer further comprises
0.01 to 1 part by mass of one or more silane coupling agents per 100 parts by mass of the acrylic polymer.

16. The pressure-sensitive adhesive sheet according to claim 5 ,
wherein the monomer components comprise 15 to 30 mass percent of the one or more nitrogen-containing monomers.

17. The pressure-sensitive adhesive sheet according to claim 5 , wherein the one or more nitrogen-containing monomers comprises cyclic N-vinylamide.

Assignees

• Nitto Denko Corp

Inventors

• Suzuki Toshihide

Classifications

• C09J133/00 Primary

  Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers · CPC title

• C09J2433/00

  Presence of (meth)acrylic polymer · CPC title

• C09J2301/416

  use of irradiation · CPC title

• C09J7/10 Primary

  without carriers · CPC title

• C09K2323/05

  Bonding or intermediate layer characterised by chemical composition, e.g. sealant or spacer · CPC title