Pressure-sensitive adhesive composition, polarizing plate, and optical member

Abstract

The present application relates to a photocurable solventless pressure-sensitive adhesive composition, a pressure-sensitive adhesive polarizing plate and a display device. According to the present application, a pressure-sensitive adhesive composition, a polarizing plate and a liquid crystal device, which have excellent durability and antistatic abilities, can be provided.

Claims

1. A pressure-sensitive adhesive polarizing plate comprising: a polarizing film; and a pressure-sensitive adhesive layer formed on at least one side of the polarizing film, wherein the pressure-sensitive adhesive layer is a photocured product of a solventless photocurable pressure-sensitive adhesive composition, and the solventless photocurable pressure-sensitive adhesive composition comprises: 40 parts by weight to 95 parts by weight of: a first resin having a weight average molecular weight in a range of 1,000,000 to 3,500,000, and comprising polymerized units derived from a (meth)acrylic acid ester monomer; 5 parts by weight to 60 parts by weight of: a second resin which is different from the first resin, wherein the second resin has a weight average molecular weight smaller than 1,000,000, and comprises polymerized units derived from 50 parts by weight to 90 parts by weight of a (meth)acrylic acid ester monomer and 10 to 50 parts by weight of a monomer represented by Formula 1 below: ##STR00002## wherein, Q is hydrogen or an alkyl group having 1 to 20 carbon atoms, each U is independently an alkylene having 1 to 4 carbon atoms, m is a number in a range of 1 to 15, and Z is hydrogen, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms; a bifunctional urethane acrylate oligomer having two acrylate groups at the terminals thereof, in a content of 0.01 to 5 parts by weight relative to 100 parts by weight of the total content of the first resin and the second resin; and an antistatic agent which is an organic salt, in a content of 0.5 to 5 parts by weight relative to 100 parts by weight of the total of the first resin and the second resin, having a uniform surface distribution in the composition.

2. The pressure-sensitive adhesive polarizing plate according to claim 1, wherein Z is hydrogen or an alkyl group having 1 to 20 carbon atoms.

3. The pressure-sensitive adhesive polarizing plate according to claim 1, when the first resin further comprises polymerized units derived from a compound capable of hydrogen bonding.

4. The pressure-sensitive adhesive polarizing plate according to claim 3, wherein the compound capable of hydrogen bonding has a hydroxyl group, a carboxyl group, a urethane group, an amine group or an amide group.

5. The pressure-sensitive adhesive polarizing plate according to claim 4, wherein the first resin comprises 30 parts by weight or less of polymerized units derived from the compound capable of hydrogen bonding.

6. The pressure-sensitive adhesive polarizing plate according to claim 1, wherein the solventless photocurable pressure-sensitive adhesive composition further comprises a multifunctional (meth)acrylate and a photoinitiator.

7. The pressure-sensitive adhesive polarizing plate according to claim 6, wherein in the solventless photocurable pressure-sensitive adhesive composition, the multifunctional (meth)acrylate is present in an amount of 5 parts by weight or less relative to 100 parts by weight of the total amount of the first resin and the second resin.

8. The pressure-sensitive adhesive polarizing plate according to claim 6, wherein in the solventless photocurable pressure-sensitive adhesive composition, the photoinitiator is present in an amount of 5 parts by weight or less relative to 100 parts by weight of the total amount of the first resin and the second resin.

9. The pressure-sensitive adhesive polarizing plate according to claim 1, wherein the pressure-sensitive adhesive layer has a surface resistance of 1×10.sup.10 Ω/sq, and peel force in a range of 300 to 700 gf/inch, as measured at a speed of 300 mm/min and an angle of 90° when peeled from a glass base material.

10. A display device comprising a liquid crystal panel that the pressure-sensitive adhesive polarizing plate according to claim 1 is attached to one side or both sides thereof.

11. The display device according to claim 10, wherein the liquid crystal panel comprises a first substrate, a pixel electrode, a first alignment film, a liquid crystal layer, a second alignment film, a common electrode and a second substrate.

12. The pressure-sensitive adhesive polarizing plate according to claim 1, wherein the polarizing film comprised a polyvinyl alcohol-based resin having a gelation degree of about 85 mol % to about 100 mol %, and a polymerization degree of about 1,000 to about 10,000.

13. A solventless photocurable pressure-sensitive adhesive composition comprising: 40 parts by weight to 95 parts by weight of: a first resin having a weight average molecular weight in a range of 1,000,000 to 3,500,000, and comprising Polymerized units derived from a (meth)acrylic acid ester monomer; 5 parts by weight to 60 parts by weight of: a second resin which is different from the first resin, wherein the second resin has a weight average molecular weight smaller than 1,000,000, and comprises polymerized units of 50 parts by weight to 90 parts by weight of a (meth)acrylic acid ester monomer and polymerized units of 10 to 50 parts by weight of a monomer represented by Formula 1 below: ##STR00003## wherein, Q is hydrogen or an alkyl group having 1 to 20 carbon atoms, each U is independently an alkylene having 1 to 4 carbon atoms, m is a number in a range of 1 to 15, and Z is hydrogen, an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms; a bifunctional urethane acrylate oligomer having two acrylate groups at the terminals thereof, in a content of 0.01 to 5 parts by weight relative to 100 parts by weight of the total content of the first resin and the second resin; and an antistatic agent which is an organic salt, in a content of 0.5 to 5 parts by weight relative to 100 parts by weight of the total of the first resin and the second resin, having a uniform surface distribution in the composition.

14. The solventless photocurable pressure-sensitive adhesive composition according to claim 13, wherein Z is hydrogen or an alkyl group having 1 to 20 carbon atoms.

15. The solventless photocurable pressure-sensitive adhesive composition according to claim 13, wherein the composition further comprises a multifunctional (meth)acrylate and a photoinitiator.

Description

BEST MODE

(1) Hereinafter, the present application will be described in detail through examples and comparative examples. However, the scope of the present application is not limited by the following examples.

(2) Evaluation Items and Evaluation Methods Weight average molecular weight: The molecular weight and molecular weight distribution (PDI) of a polymer were measured using GPC (gel permeation chromatograph), and GPC measurement conditions were as follows. The calibration curve was prepared using standard polystyrene (manufactured by Aglient system), and the measurement result was converted into the weight average molecular weight (Mw).

(3) <GPC Measurement Conditions>

(4) Measuring instrument: Aglient GPC (Aglient 1200 series, U.S.)

(5) Column: two PL Mixed B connections

(6) Column temperature: 40° C.

(7) Eluent: THF (tetrahydrofuran)

(8) Flow rate: 1.0 mL/min

(9) Concentration: ˜1 mg/mL (100 μl injection) Surface resistance: The surface resistance of a pressure-sensitive adhesive layer was measured using a Hiresta-UX surface resistance meter, and measurement conditions were as follows.

(10) <Surface Resistance Measurement Conditions>

(11) Measuring instrument: Hiresta-UX

(12) Applied voltage: 100V

(13) Time: 30 seconds

(14) Environment (temperature/humidity): 25 degrees, 50% RH High temperature and high humidity durability: A pressure-sensitive adhesive layer was cut to a size of 8×13 cm, attached to soda-lime glass and then placed in a chamber at a 60° C./90% RH condition, and after 500 hours, it was observed whether or not bubbles were generated.

(15) <Evaluation Criteria>

(16) Presence of bubbles observed with naked eyes: NG

(17) Absence of bubbles observed with naked eyes: OK Light leakage shielding ability: Two optical members including a pressure-sensitive adhesive layer to be produced below and a polarizing plate were laminated on soda-lime glass so as to be orthogonal to each other, and the laminate was maintained in an autoclave under the conditions of 40° C., 4 bar and 20 minutes to produce a test plate. The prepared test plate was allowed to stand at a condition of 80° C. for 500 hours, and the degree of light leakage was visually observed and evaluated according to the following criteria.

(18) <Evaluation Criteria>

(19) Almost no light leakage: good

(20) Slight light leakage: normal

(21) Apparent light leakage: NG Peel force: The pressure-sensitive adhesive film was cut to a width of 1 inch, attached to soda-lime glass and allowed to stand at room temperature for 1 hour, and then the peel force was measured. At this time, the room temperature is a temperature that no warming or cooling is performed artificially, which is a temperature in a range of 18 to 30° C.

(22) <Measurement Conditions>

(23) Measuring instrument: tensile machine from TA (Texture Analyzer) instrument

(24) Measuring angle: 900

(25) Measuring speed: 300 mm/min

(26) <Evaluation Criteria>

(27) 300 to 700 gf/inch: proper

(28) Less than 300 gf/inch: improper

EXAMPLES AND COMPARATIVE EXAMPLES

Example 1

(29) Production of first resin (A): 85 parts by weight of BA (n-butyl acrylate), 5 parts by weight of DMAA (dimethyl acrylamide) and 10 parts by weight of HBA (hydroxybutyl acrylate) were bulk-polymerized at 50° C. and normal pressure to obtain a first resin having a weight average molecular weight of 2,500,000.

(30) Production of second resin (B): 60 parts by weight of BA (n-butyl acrylate) and 40 parts by weight of EOEOEA (2-(2-ethoxyethoxy)ethyl acrylate) were bulk-polymerized to obtain a second resin having a weight average molecular weight of 300,000.

(31) A composition comprising 70 parts by weight of the first resin and 30 parts by weight of the second resin, as prepared above, and 0.3 parts by weight of an initiator (irgacure-819), 1.0 part by weight of a urethane acrylate-based curing agent (Miwon Specialty Chemicals, SUO-1020) and 1.5 parts by weight of an antistatic agent (FC-4400) was coated on a release base material with a comma coater. Then, it was irradiated with light having a wavelength of 368 nm by a Sylvania black light lamp for about 4 minutes to produce a pressure-sensitive adhesive layer. The evaluated properties are as shown in Table 2.

Example 2

(32) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that the content between the resins was changed as in Table 1 below.

Comparative Example 1

(33) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that 100 parts by weight of one resin having the composition shown in Table 1 below was used.

Comparative Example 2

(34) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that 100 parts by weight of one resin having the composition as shown in Table 1 below was used.

Comparative Example 3

(35) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that 100 parts by weight of one resin having the composition as shown in Table 1 below was used.

Comparative Example 4

(36) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that two resins having the compositions as shown in Table 1 below were used.

Comparative Example 5

(37) A pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except that two resins having the compositions as shown in Table 1 below were used.

(38) TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 1 2 3 4 5 Resin BA ratio 85 85 — — 85 85 A DMAA ratio 5 5 — — 5 5 HBA ratio 10 10 — — 10 10 Mw (×10,000) 250 250 — — 250 250 Resin BA ratio 60 60 — — 30 60 B EOEOEA ratio 40 40 — — 70 40 Mw (×10,000) 30 30 — — 30 100 Resin BA — — 85 65 85 — — C DMAA — — 5 5 5 — — HBA — — 10 10 10 — — EOEOEA — — — 20 — — — Mw (×10,000) — — 250 250 250 — — Curing Agent (SUO-1020) 1 1 1 1 1 1 1 Initiator (irgacure-819) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Antistatic Agent 1.5 1.5 1.5 1.5 5 1.5 1.5 (FC-4400) Ratio between Resins 70:30:0 50:50:0 0:0:100 0:0:100 0:0:100 50:50:0 50:50:0 (A:B:C) (A:B:C) (A:B:C) (A:B:C) (A:B:C) (A:B:C) (A:B:C) Ratio between monomers or resins: part by weight BA: n-butyl acrylate HBA: 4-hydroxybutyl acrylate DMAA: dimethyl acrylamide EOEOEA: 2-(2-ethyoxyethyoxy)ethyl acrylate

(39) TABLE-US-00002 TABLE 2 Example Comparative Example 1 2 1 2 3 4 5 Surface Resistance 0.354 0.11 9.33 4.23 0.23 0.09 0.251 (×1010) (Ω/□) High Temperature/High OK OK OK OK NG NG NG Humidity Durability Light Leakage Ability Good Good Good Good Good Good Good Peel Force (gf/inch) Proper Proper Proper Proper Improper Improper Improper (503 (429 (410 (337 (153 (214 (233 gf/inch) gf/inch) gf/inch) gf/inch) gf/inch) gf/inch) gf/inch)

(40) In the case of Examples, all of the evaluated physical properties are excellent. On the other hand, in the case of Comparative Examples having no configuration according to the present invention, it can be seen that the measured physical properties are poor.

(41) Specifically, in the case of Comparative Example 3 comprising a relatively excessive amount of the antistatic agent to reduce the surface resistance, high temperature/high humidity durability and adhesive force are poor due to bleeding out of the antistatic agent. In the case of Comparative Example 4 comprising an excessive amount of EOEOEA, the surface resistance is lowered, but the compatibility between resins is lowered and thus high temperature/high humidity durability and adhesive force are poor. In the case of Comparative Example 5 that the second resin have a weight average molecular weight of 1,000,000, it can be seen that the antistatic function by the second resin is not sufficient and both the durability and the adhesive force are not good.