Adhesive composition, protective film for a polarizing plate, polarizing plate, and liquid crystal display

• US 10,640,688 B2
• Filed: 04/12/2017
• Issued: 05/05/2020
• Est. Priority Date: 07/01/2008
• Status: Active Grant

• Current Assignee: Shanjin Optoelectronics Company Limited
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Kim, Se Ra, Kim, Kee Young, Han, In Cheon
• Primary Examiner(s): Zhang, Ruiyun
• Application Number:
  US15/486,150
• Publication Number:
  US 20170247585A1
• Time in Patent Office: 1,119 Days
• Field of Search: 428 154, 428354, 428355 AC, 349117, 349118, 349119, 349122, 35948902, 35949201, 35948903, 524556
• CPC Class Codes: B32B 2255/26 Polymeric coating
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/1802 C2-(meth)acrylate, e.g. ethyl (meth)acrylate
• CPC Class Codes: C08F 220/1804 C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• CPC Class Codes: C08F 220/20 of polyhydric alcohols or phenols , e.g. 2-hydroxyethyl (meth)acrylate or glycerol mono-(meth)acrylate
• CPC Class Codes: C08F 220/281 and containing only one oxygen, e.g. furfuryl (meth)acrylate or 2-methoxyethyl (meth)acrylate
• CPC Class Codes: C08F 220/30 containing aromatic rings in the alcohol moiety
• CPC Class Codes: C08F 220/301 and one oxygen in the alcohol moiety
• CPC Class Codes: C08G 18/6254 Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
• CPC Class Codes: C08G 18/8029 Masked aromatic polyisocyanates
• CPC Class Codes: C09D 133/066 containing -OH groups
• CPC Class Codes: C09J 133/08 Homopolymers or copolymers of acrylic acid esters
• 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 2301/302 the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/05 Bonding or intermediate layer characterised by chemical composition, e.g. sealant or spacer
• CPC Class Codes: C09K 2323/057 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: G02B 1/14 : Protective coatings, e.g. hard coatings
• CPC Class Codes: G02F 1/133528 : Polarisers
• CPC Class Codes: G02F 2202/28 : Adhesive materials or arrangements
• CPC Class Codes: Y10T 428/2848 : Three or more layers
• CPC Class Codes: Y10T 428/2891 : including addition polymer from alpha-beta unsaturated carboxylic acid [e.g., acrylic acid, methacrylic acid, etc.] Or derivative thereof

Abstract

The present invention relates to a pressure-sensitive adhesive composition, a protective film for polarizers, which includes a cured product of the pressure-sensitive adhesive composition, a polarizer, and a liquid crystal display (LCD). In the present invention, a pressure-sensitive adhesive showing excellent endurance reliability in high-temperature and/or high-humidity conditions and having superior physical properties such as cuttability, re-peeling property, and workability can be provided. In particular, it is possible to provide the pressure-sensitive adhesive composition which can prevent light leakage that may occur in an LCD, even when being applied to a film having a low stress optical coefficient.

Claims

1. A polarizer comprising:

a polarizing film or polarizing element; and

a protective film attached to a side or both sides of the polarizing film or polarizing element,

wherein the protective film comprises;

a base film on the polarizing film or polarizing element, and

a pressure sensitive adhesive layer in direct contact with a side of the base film opposite to the polarizing film or polarizing element,

wherein the base film is a cycloolefine polymer film or an acrylic film,

wherein a stress optical coefficient of the base film is 6 brewster or less and wherein the pressure sensitive adhesive layer is a cured product of a pressure-sensitive adhesive composition satisfying a condition of General Formula 1 given below and wherein the pressure-sensitive adhesive composition comprises a base resin comprising an aromatic ring-containing monomer or the pressure-sensitive adhesive composition comprises a compound having a positive stress optical coefficient;

Δ

X≤

2 nm, 

 

[General Formula 1]

wherein Δ

X represents an absolute value of a phase retardation (R_in) in a surface-direction, the phase retardation being measured by an equation, R_in={(n_x−

n_y)×

d}, when a sheet-shaped pressure-sensitive adhesive that has a width of 10 mm and a length of 20 mm and that is prepared by using the pressure-sensitive adhesive composition is elongated by 500 μ

m in a longitudinal direction at 23°

C., wherein n_x represents a refractive index along a horizontal axis in a surface of the sheet-shaped pressure-sensitive adhesive, n_y represents a refractive index along a vertical axis in the surface of the sheet-shaped pressure-sensitive adhesive, and d represents a thickness of the sheet-shaped pressure-sensitive adhesive.

2. The polarizer of claim 1, wherein the protective film includes only one base film.

3. The polarizer of claim 1, wherein the stress optical coefficient of the base film is 3 brewster or less.

4. The polarizer of claim 1, wherein the Δ

X of the General Formula 1 is 1.5 nm or less.

5. The polarizer of claim 1, wherein the Δ

X of the General Formula 1 is 1 nm or less.

6. The polarizer of claim 1, wherein the compound having the positive stress optical coefficient is expressed by Formula 3 or Formula 4:

7. The polarizer according to claim 1, wherein the base resin has a weight average molecular weight of 500,000 or more.

8. The polarizer of claim 7, wherein the base resin is a polymer of a monomer mixture comprising a (meth)acrylic acid ester monomer;

and a crosslinking monomer.

9. The polarizer of claim 1, wherein the base resin is a polymer of a monomer mixture and wherein the monomer mixture comprises a (meth)acrylic acid ester monomer;

a crosslinking monomer and a compound expressed by Formula 2 given below;

10. The polarizer of claim 9, wherein the pressure-sensitive adhesive composition further comprises a crosslinking agent crosslinking the base resin and wherein the crosslinking agent consists of one or more selected from a group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound.

11. A liquid crystal display comprising a liquid crystal panel and the polarizer of claim 1, wherein the pressure-sensitive adhesive layer is attached on the liquid crystal panel.