Pressure-sensitive adhesive sheet

Patent metadata

Field	Value
Publication number	US-11236253-B2
Application number	US-201815862989-A
Country	US
Kind code	B2
Filing date	Jan 5, 2018
Priority date	Jan 10, 2017
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

Provided is a PSA sheet highly durable against repeated deformation and suited for use in a flexible device as well. The PSA sheet provided by this invention comprises a PSA layer. The PSA sheet shows a recovery rate at 100% elongation of 70% or higher. The PSA layer shows a displacement of 0.5 mm or greater according to the following holding power test:<Holding Power Test>At 23° C., the PSA layer is applied over a 10 mm wide by 20 mm long bonding area to a Bakelite plate as an adherend; a 1 kg load is applied in the length direction; after one hour, the displacement from the initial position where first applied is determined.

First claim

What is claimed is:

1. A pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer provided on at least one face of the substrate, wherein
the substrate is a non-porous polyurethane-based resin film,
the pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive comprising a base polymer and a tackifier resin,
the tackifier resin consists of one or more species of tackifier resin T L having a softening point of from 50° C. to less than 105° C.,
the pressure-sensitive adhesive sheet has a thickness of 15 μm or greater,
the substrate has a thickness of 10 μm or greater, and
the pressure-sensitive adhesive layer has a thickness of 5 μm or greater; wherein
the PSA sheet shows a recovery rate at 100% elongation of 70% or higher, and
the pressure-sensitive adhesive layer shows a displacement of 0.5 mm or greater according to the following holding power test:
<Holding power test>

At 23° C., the pressure-sensitive adhesive layer is applied over a 10 mm wide by 20 mm long bonding area to a polyoxybenzylmethylenglycolanhydride plate as an adherend; a 1 kg load is applied in the length direction; after one hour, the displacement from the initial point where first applied is determined.

2. The pressure-sensitive adhesive sheet according to claim 1 , showing a maximum tensile strength at 100% elongation of 15 N/10 mm or less.

3. The pressure-sensitive adhesive sheet according to claim 1 , having a thickness of 250 μm or less.

4. The pressure-sensitive adhesive sheet according to claim 1 , wherein
the tackifier resin content in the pressure-sensitive adhesive layer is greater than 10 parts by weight to 100 parts by weight of the base polymer.

5. The pressure-sensitive adhesive sheet according to claim 1 , wherein the base polymer is an acrylic polymer.

6. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer comprises a crosslinking agent.

7. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer shows a distance returned of 0.05 mm or greater at 5 minutes after the load is removed in the holding power test.

8. The pressure-sensitive adhesive sheet according to claim 1 , wherein the substrate is a stretchable substrate.

9. The pressure-sensitive adhesive sheet according to claim 1 , wherein the base polymer has a glass transition temperature of −25° C. or lower.

10. The pressure-sensitive adhesive sheet according to claim 4 , wherein
the tackifier resin content is 15 parts by weight or greater to 100 parts by weight of the base polymer.

11. The pressure-sensitive adhesive sheet according to claim 10 , wherein the tackifier resin comprises a rosin-based resin.

12. The pressure-sensitive adhesive sheet according to claim 6 , wherein the crosslinking agent comprises an isocyanate-based crosslinking agent.

13. The pressure-sensitive adhesive sheet according to claim 12 , wherein the base polymer of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is an acrylic polymer, the acrylic polymer is a polymer of a monomer mixture comprising a hydroxy group-containing monomer, the isocyanate-based crosslinking agent is used in an amount up to 40 times that of the hydroxy group-containing monomer.

14. The pressure-sensitive adhesive sheet according to claim 1 , having a maximum tensile strength of 7 N/10 mm or less.

15. The pressure-sensitive adhesive sheet according to claim 1 , having an elongation at break of 200% or greater.

16. The pressure-sensitive adhesive sheet according to claim 1 , having a thickness of 30 μm or greater.

17. The pressure-sensitive adhesive sheet according to claim 1 for use in a flexible device.

Assignees

• Nitto Denko Corp

Inventors

• Yamanari Yusuke
• Saito Makoto
• Higuchi Naoaki
• Jozuka Kenta

Classifications

• C09J133/14

  of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen · CPC title

• C09J133/00

  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

• C09J11/08

  Macromolecular additives · CPC title

• C09J2301/312

  parameters being the characterizing feature · CPC title

• C09J2423/006

  in the substrate · CPC title