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

• US 9,663,687 B2
• Filed: 07/01/2009
• Issued: 05/30/2017
• 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:
  US13/001,778
• Publication Number:
  US 20110177262A1
• Time in Patent Office: 2,890 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, and

a pressure sensitive adhesive layer on a side or both sides of the base film,

wherein the pressure sensitive adhesive layer comprises a cured product of a pressure-sensitive adhesive composition satisfying a condition of General Formula 1 given below;

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,

wherein the base film is a saturated cycloolefin film;

an olefin thermoplastic resin film having a substituted or unsubstituted imide group in its side chain;

a thermoplastic resin film having a substituted or unsubstituted phenyl group and nitrile group in its side chain;

or an acrylic film,

wherein a stress optical coefficient of the saturated cycloolefin film;

the olefin thermoplastic resin film having a substituted or unsubstituted imide group in its side chain;

the thermoplastic resin film having a substituted or unsubstituted phenyl group and nitrile group in its side chain is 6 brewster or less, and the stress optical coefficient of the acrylic film is 3 brewster or less, and

wherein the pressure sensitive adhesive composition comprises a compound having a positive stress optical coefficient expressed by Formula 3 or Formula 4;

2. The polarizer of claim 1, wherein the pressure-sensitive adhesive composition further comprises a base resin having a weight average molecular weight of 500,000 or more.

3. The polarizer of claim 2, wherein the base resin is a polymer of a monomer mixture comprising 80 to 99.8 parts by weight of a (meth)acrylic acid ester monomer;

and 0.01 to 10 parts by weight of a crosslinking monomer.

4. The polarizer of claim 3, wherein the (meth)acrylic acid ester monomer is one or more selected from a group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, and tetradecyl (meth)acrylate.

5. The polarizer of claim 3, wherein the crosslinking monomer is one or more selected from a group consisting of a hydroxy group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer.

6. The polarizer of claim 3, wherein the monomer mixture further comprises a monomer expressed by:

7. The polarizer of claim 3, wherein the monomer mixture further comprises a compound expressed by:

8. The polarizer of claim 2, wherein the pressure sensitive adhesive composition further comprises 0.1 to 10 parts by weight of a crosslinking agent relative to 100 parts by weight of the base resin.

9. The polarizer of claim 8, wherein the crosslinking agent is one or more selected from a group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound.

10. The polarizer of claim 2, wherein the pressure-sensitive adhesive composition further comprises 0.01 to 10 parts by weight of a silane coupling agent relative to 100 parts by weight of the base resin.

11. The polarizer of claim 1, wherein the acrylic film comprises an acrylic resin;

and a graft copolymer containing a conjugated diene rubber.

12. The polarizer of claim 1, further comprising one or more selected from a group consisting of a protective layer, a reflective layer, an anti-glare layer, a phase retardation film, a compensation film for wide view angle, and a brightness enhancement film.

13. A liquid crystal display comprising a liquid crystal panel in which the polarizer according to claim 1 is attached on a face or both faces of a liquid crystal cell.

14. The polarizer of claim 1, wherein the Δ

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

15. The polarizer of claim 1, wherein the Δ

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

16. 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 disposed on the polarizing film or polarizing element, and

a pressure sensitive adhesive layer disposed on a side of the base film opposite to the polarizing film or polarizing element,

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;

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,

wherein the base film is a saturated cycloolefine film, an olefine thermoplastic resin film having a substituted or unsubstituted imide group in its side chain;

a thermoplastic resin film having a substituted or unsubstituted phenyl group and nitrile group in its side chain;

or an acrylic film,

wherein a stress optical coefficient of the saturated cycloolefine film, the olefine thermoplastic resin film having a substituted or unsubstituted imide group in its side chain;

or the thermoplastic resin film having a substituted or unsubstituted phenyl group and nitrile group in its side chain is 6 brewster or less and a stress optical coefficient of the acrylic film is 3 brewster or less,

wherein the pressure-sensitive adhesive composition comprises;

a base resin that is a polymer of a monomer mixture including a (meth)acrylic acid ester monomer, a crosslinking monomer and a compound expressed by Formula 2 given below; and

a crosslinking agent crosslinking the base resin;

17. The polarizer of claim 16, wherein the protective film comprises only one base film.