OPTICAL PRESSURE-SENSITIVE ADHESIVE SHEET, OPTICAL FILM AND DISPLAY DEVICE

• US 20120100359A1
• Filed: 10/20/2011
• Published: 04/26/2012
• Est. Priority Date: 10/21/2010
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: KISHIOKA, Hiroaki, FUMOTO, Hiroaki, NATSUI, Masatomo
• Granted Patent: US 9,695,337 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C09J 133/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C09J 133/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C09J 133/14 of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
• CPC Class Codes: C09J 133/24 Homopolymers or copolymers of amides or imides
• CPC Class Codes: C09J 2203/318 for the production of liquid crystal displays
• CPC Class Codes: C09J 2301/302 the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
• CPC Class Codes: C09J 2433/00 Presence of (meth)acrylic polymer
• CPC Class Codes: C09J 7/385 Acrylic polymers

Abstract

The present invention provides an optical pressure-sensitive adhesive sheet in which white turbidity is not caused by humidification and durability is excellent as well. The present invention provides an optical pressure-sensitive adhesive sheet, comprising: a pressure-sensitive adhesive layer in which a moisture ratio after storage under an environment of 60° C. and 95% RH for 120 hours is 0.65 wt % or more, and a shear storage elastic modulus at 85° C. which is measured by a dynamic viscoelastic measurement is 5.0×10⁴ to 5.0×10⁵ Pa, wherein a peeling distance measured by the constant-load peel test is 30 mm or less when an adherend is a polyethylene terephthalate plate, and the peeling distance measured by the following constant-load peel test is 30 mm or less when the adherend is an acrylic plate.

Claims

1. An optical pressure-sensitive adhesive sheet, comprising:

a pressure-sensitive adhesive layer in which a moisture ratio after storage under an environment of 60°

C. and 95% RH for 120 hours is 0.65 wt % or more, and a shear storage elastic modulus at 85°

C. which is measured by a dynamic viscoelastic measurement is 5.0×

10⁴ to 5.0×

10⁵ Pa,

wherein a peeling distance measured by the following constant-load peel test is 30 mm or less when an adherend is a polyethylene terephthalate plate, and the peeling distance measured by the following constant-load peel test is 30 mm or less when the adherend is an acrylic plate;

constant-load peel test;

a surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a size of 20 mm in width and 60 mm in length is laminted to one surface of the adherend, followed by treating in an autoclave under a condition of 50°

C. and 5 atm for 15 min, and subsequently, a load of 100 gf in a direction which is vertical to the surface of the adherend is applied to an end of the pressure-sensitive adhesive sheet in a length direction under a condition of 23°

C. and 50% RH, and the peeling distance of the pressure-sensitive adhesive sheet after the passage of 3 hours is measured.

2. The optical pressure-sensitive adhesive sheet according to claim 1, wherein a total amount of an acrylic acid ion and methacrylic acid ion which are extracted with pure water under a condition of 100°

C. and 45 min, which is measured by an ion chromatograph method, is 20 ng/cm² or less per unit area of the pressure-sensitive adhesive layer.

3. The optical pressure-sensitive adhesive sheet according to claim 1, wherein a gel fraction of the pressure-sensitive adhesive layer is 40 to 95%.

4. The optical pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer comprises an acrylic polymer including, as a monomer component, a methyl methacrylate in an amount of 5 to 20 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

5. The optical pressure-sensitive adhesive sheet according to claim 4, wherein the acrylic polymer includes, as a monomer component, a hydroxyl group-containing monomer in an amount of 10 to 25 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

6. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 1.

7. A display device comprising the optical pressure-sensitive adhesive sheet according to claim 1.

8. The optical pressure-sensitive adhesive sheet according to claim 2, wherein a gel fraction of the pressure-sensitive adhesive layer is 40 to 95%.

9. The optical pressure-sensitive adhesive sheet according to claim 2, wherein the pressure-sensitive adhesive layer comprises an acrylic polymer including, as a monomer component, a methyl methacrylate in an amount of 5 to 20 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

10. The optical pressure-sensitive adhesive sheet according to claim 3, wherein the pressure-sensitive adhesive layer comprises an acrylic polymer including, as a monomer component, a methyl methacrylate in an amount of 5 to 20 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

11. The optical pressure-sensitive adhesive sheet according to claim 8, wherein the pressure-sensitive adhesive layer comprises an acrylic polymer including, as a monomer component, a methyl methacrylate in an amount of 5 to 20 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

12. The optical pressure-sensitive adhesive sheet according to claim 9, wherein the acrylic polymer includes, as a monomer component, a hydroxyl group-containing monomer in an amount of 10 to 25 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

13. The optical pressure-sensitive adhesive sheet according to claim 10, wherein the acrylic polymer includes, as a monomer component, a hydroxyl group-containing monomer in an amount of 10 to 25 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

14. The optical pressure-sensitive adhesive sheet according to claim 11, wherein the acrylic polymer includes, as a monomer component, a hydroxyl group-containing monomer in an amount of 10 to 25 wt % based on a total amount (100 wt %) of the monomer component constituting the acrylic polymer.

15. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 2.

16. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 3.

17. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 8.

18. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 4.

19. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 9.

20. An optical film comprising the optical pressure-sensitive adhesive sheet according to claim 10.