Polarizing plate

Abstract

Provided are a polarizing plate and a liquid crystal display device. The polarizing plate has lighter weight, a smaller thickness, and excellent physical properties such as water resistance, workability, durability, and light leakage preventing ability. In addition, the polarizing plate prevents curling occurring at the polarizing plate or a polarizer in formation thereof, and has excellent thermal resistance or thermal shock resistance.

Claims

1. A polarizing plate, comprising: a polarizer; an active energy beam-curable adhesive layer having a thickness of 0.1 to 30 m; and a pressure-sensitive adhesive layer having first and second surfaces and a thickness of 10 to 80 m, which are sequentially disposed, wherein the active energy beam-curable adhesive layer includes an adhesive composition including an epoxy compound and an acryl-based monomer in a cured state, and having a glass transition temperature after curing of 50 C. or more, wherein the active energy beam-curable adhesive layer is directly attached to at least one surface of the polarizer, and the pressure-sensitive adhesive layer is directly attached to the active energy beam-curable adhesive layer, wherein the first surface has a higher tensile modulus than the second surface, and the first surface is directly attached to the active energy beam-curable adhesive layer, and wherein the first surface has a tensile modulus at 25 C. of 100 to 1,000 MPa and the second surface has a tensile modulus at 25 C. of 0.01 to 0.5 MPa, wherein the pressure-sensitive adhesive layer comprises a first pressure-sensitive adhesive layer forming the first surface and a second pressure-sensitive adhesive layer forming the second surface, wherein the first pressure-sensitive adhesive layer comprises a crosslinking structure of an acryl polymer crosslinked by a multifunctional crosslinking agent and a crosslinking structure of polymerized multifunctional acrylate and wherein the second pressure-sensitive adhesive layer is formed from a heat-curable or room temperature-curable pressure-sensitive adhesive composition and comprises an acryl polymer crosslinked by a multifunctional crosslinking agent.

2. The polarizing plate according to claim 1, wherein the epoxy compound is crosslinked or polymerized by a cationic reaction and wherein the adhesive composition further includes a cationic initiator.

3. The polarizing plate according to claim 2, wherein the acryl-based monomer is a radical polymerizable compound and wherein the adhesive composition further includes a photoinitiator as a radical initiator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing a structure of an exemplary polarizing plate;

(2) FIGS. 2 and 3 are cross-sectional views showing exemplary pressure-sensitive adhesive layers of the present application; and

(3) FIG. 4 is a schematic diagram showing a method of evaluating curling characteristics.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(4) Hereinafter, the present application will be described with reference to Examples according to the present application and Comparative Examples not according to the present application in detail. However, the scope of the present application is not limited to the following Examples.

Preparation Example 1. Preparation of Acryl Resin (A)

(5) 63 parts by weight of n-butyl acrylate (n-BA), 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA) and 35 parts by weight of 2-methoxyethyl acrylate were put into a 1 L reactor refluxing nitrogen gas and equipped with a cooling device to facilitate temperature control. Subsequently, 0.04 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight controlling agent, based on 100 parts by weight of the monomer, and ethyl acetate (EAc) as a solvent were put into the reactor, and then the resulting mixture was purged with nitrogen gas for 60 minutes to remove oxygen. Afterward, the temperature was maintained at 64 C., 0.05 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator, based on 100 parts by weight of the monomer, was put into the reactor, and the reaction was carried out for 7 hours. After the reaction, the reaction product was diluted with ethyl acetate, and thus an acryl resin (A) having a weight average molecular weight of 550,000 was prepared.

Preparation Example 2. Preparation of Acryl Resin (B)

(6) 99 parts by weight of n-butyl acrylate (n-BA) and 2 parts by weight of 2-hydroxyethyl acrylate (2-HEA) were put into a 1 L reactor refluxing nitrogen gas and equipped with a cooling device to facilitate temperature control. Subsequently, ethyl acetate (EAc) as a solvent was put into the reactor, and then the resulting mixture was purged with nitrogen gas for 60 minutes to remove oxygen. Afterward, the temperature was maintained at 64 C., 0.05 parts by weight of azobisisobutyronitrile (AIBN) as a reaction initiator, based on 100 parts by weight of the monomer, was put into the reactor, and the reaction was carried out for 7 hours. After the reaction, the reaction product was diluted with ethyl acetate, and thus an acryl resin (B) having a weight average molecular weight of 1,800,000 was prepared.

Preparation Example 3. Preparation of Adhesive Composition (A)

(7) An adhesive composition having a glass transition temperature of 52 C. was prepared by mixing 38.5 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 10 parts by weight of phenoxyethyl acrylate, 15 parts by weight of isobornyl acrylate, and 15 parts by weight of Celloxide 2021P, which is an epoxy resin, and 15 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide), 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator, and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 4. Preparation of Adhesive Composition (B)

(8) An adhesive composition having a glass transition temperature of 54 C. was prepared by mixing 44.5 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 15 parts by weight of phenoxyethyl acrylate, 9 parts by weight of isobornyl acrylate, 15 parts by weight of Celloxide 2021P, which is an epoxy resin and 10 parts by weight of a novolac epoxy resin having a molecular weight of 3,000, poly[(phenyl glycidyl ether)-co-formaldehyde] as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide), 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator, and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 5. Preparation of Adhesive Composition (C)

(9) An adhesive composition having a glass transition temperature of 61 C. was prepared by mixing 15 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 20 parts by weight of phenoxyethyl acrylate, 9.5 parts by weight of isobornyl acrylate, and 25 parts by weight of Celloxide 2021P, which is an epoxy resin, and 24 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide), 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator, and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 6. Preparation of Adhesive Composition (D)

(10) An adhesive composition having a glass transition temperature of 69 C. was prepared by mixing 20 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 13 parts by weight of phenoxyethyl acrylate, 9.5 parts by weight of isobornyl acrylate, and 28 parts by weight of Celloxide 2021P, which is an epoxy resin, and 23 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide), 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator, and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 7. Preparation of Adhesive Composition (E)

(11) An adhesive composition having a glass transition temperature of 80 C. was prepared by mixing 23 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 10 parts by weight of phenoxyethyl acrylate, 8 parts by weight of isobornyl acrylate, 26 parts by weight of Celloxide 2021P, which is an epoxy resin, 13 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) and 14 parts by weight of a novolac epoxy resin having a molecular weight of 3,000, poly[(phenyl glycidyl ether)-co-formaldehyde] as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide) and 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator with the mixed product.

Preparation Example 8. Preparation of Adhesive Composition (F)

(12) An adhesive composition having a glass transition temperature of 112 C. was prepared by mixing 18 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 12 parts by weight of isobornyl acrylate, and 39 parts by weight of Celloxide 2021P, which is an epoxy resin, and 24.5 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) as epoxy compounds, and mixing 3 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide), 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator, and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 9. Preparation of Adhesive Composition (G)

(13) An adhesive composition having a glass transition temperature of 112 C. was prepared by mixing 51.5 parts by weight of Celloxide 2021P, which is an epoxy resin, and 45 parts by weight of 1,4-cyclohexane dimethanol diglycidyl ether (CHDMGDE, Hajin Chemtech) as an epoxy compound, and mixing 3 parts by weight of an iodide initiator (Irgacure 250, Ciba Specialty Chemicals) as a cationic initiator and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

Preparation Example 10. Preparation of Adhesive Composition (H)

(14) An adhesive composition having a glass transition temperature of 25 C. was prepared by mixing 55 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 20 parts by weight of phenoxyethyl acrylate, 15 parts by weight of isobornyl acrylate, and 5 parts by weight of a novolac epoxy resin having a molecular weight of 3,000, poly[(phenyl glycidyl ether)-co-formaldehyde] as an epoxy compound, and mixing 4 parts by weight of a radical initiator (TPO, Darocure TPO) and 1 part by weight of IHT-PI43 (including 50% mixed triarylsulfonium hexafluorophosphate salt and 50% Propylene carbonate) as a cationic initiator with the mixed product.

Preparation Example 11. Preparation of Adhesive Composition (I)

(15) An adhesive composition having a glass transition temperature of 40 C. was prepared by mixing 46 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 20 parts by weight of phenoxyethyl acrylate, 15 parts by weight of isobornyl acrylate, and 5 parts by weight of a novolac epoxy resin having a molecular weight of 3,000, poly[(phenyl glycidyl ether)-co-formaldehyde] as a cationic reactive compound, and mixing 4 parts by weight of a radical initiator (TPO, Darocure TPO), 3 parts by weight of an iodine salt as a cationic polymerization initiator, and 2 parts by weight of a photosensitizer (diethyl thioxanthone, Kayacure DTEX-S, Nippon Kayaku Co. Ltd.) with the mixed product.

Preparation Example 12. Preparation of Adhesive Composition (J)

(16) An adhesive composition having a glass transition temperature of 24 C. was prepared by mixing 68.5 parts by weight of 2-hydroxylethyl acrylate (2-HEA), 12 parts by weight of phenoxyethyl acrylate, and 15 parts by weight of isobornyl acrylate, and mixing 4 parts by weight of a radical initiator (CGI 819, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide) and 0.5 parts by weight of a photosensitizer (isopropyl thioxanthone, Aldrich) with the mixed product.

(17) The compositions and glass transition temperatures of the prepared adhesive compositions are listed in Table 1.

(18) TABLE-US-00001 TABLE 1 Adhesive composition A B C D E F G H I J Composition Acryl- 2-HEA 38.5 44.5 15 20 23 18 0 55 46 68.5 (parts based PEA 10 15 20 13 10 0 0 20 10 12 by monomer IBOA 15 9 9.5 9.5 8 12 0 15 30 15 weight) Epoxy 2021P 15 15 25 28 26 39 51.5 0 0 0 compound CHDMDGDE 15 0 24 23 13 24.5 45 0 0 0 Novolac 0 10 0 0 14 0 0 5 5 0 Radical initiator 3 3 3 3 3 3 0 4 4 4 Photoinitiator 3 3 3 3 3 3 3 1 3 0 Photosensitizer 0.5 0.5 0.5 0.5 0 0.5 0.5 0 2 0.5 Glass transition 52 54 61 69 80 97 112 25 40 24 temperature( C.) 2-HEA: 2-hydroxyethyl acrylate PEA: phenoxyethyl acrylate IBOA: isobornyl acrylate 2021P: Celloxide 2021P CHDMDGDE: 1,4-cyclohexanedimethanol diglycidylether Novolac: poly[(phenyl glycidyl ether)-co-formaldehyde]

Example 1

Preparing First Pressure-Sensitive Adhesive Layer

(19) A first pressure-sensitive adhesive composition was prepared by mixing 100 parts by weight of the acryl resin (A), 80 parts by weight of pentaerythritol triacrylate as a multifunctional acrylate, 3 parts by weight of 2-hydroxy-2-methylphenylpropane-1-one as a photoinitiator, 5 parts by weight of a crosslinking agent (TDI-based isocyanate, Coronate L, Nippon Polyurethane Industry (Japan)) and 0.1 parts by weight of a silane coupling agent (KBM-403, Shin-Etsu (Japan), -glycidoxypropyltrimethoxy silane), diluting the mixed product with a solvent to having a solid content of 35 wt %, and uniformly mixing the resulting product. Subsequently, the prepared pressure-sensitive adhesive composition was coated on a surface of a poly(ethylene terephthalate) (PET) film (thickness: 38 m, MRF-38, Mitsubishi) treated with releasing treatment with a silicon compound to have a dry thickness of 25 m, and the resulting film was dried in an oven at 110 C. for 3 minutes. Then, the releasing-treated surface of PET film subjected to releasing treatment (thickness: 38 m, MRF-38, Mitsubishi) was further laminated on the dried coating layer, and UV rays were radiated under the following conditions, thereby forming a first pressure-sensitive adhesive layer. Tensile modulus (at 25 C.) of the formed first pressure-sensitive adhesive layer was 400 MPa. In the embodiment, the tensile modulus was measured according to the following method.

(20) <Conditions for UV Radiation>

(21) UV Radiation Tool: High Pressure Mercury Lamp

(22) Radiation Conditions: Luminance: 600 mW/cm.sup.2 Intensity of Radiation: 150 mJ/cm.sup.2

(23) Preparing Second Pressure-Sensitive Adhesive Layer

(24) A Second pressure-sensitive adhesive composition was prepared by mixing 100 parts by weight of the acryl resin (B), 15 parts by weight of pentaerythritol triacrylate as a multifunctional acrylate, 3 parts by weight of 2-hydroxy-2-methylphenylpropane-1-one as a photoinitiator, 0.5 parts by weight of a crosslinking agent (TDI-based isocyanate, Coronate L, Nippon Polyurethane Industry (Japan)) and 0.1 parts by weight of a silane coupling agent (KBM-403, Shin-Etsu (Japan), -glycidoxypropyltrimethoxy silane), diluting the mixed product with a solvent to having a solid content of 13 wt %, and uniformly mixing the resulting product. Subsequently, the prepared pressure-sensitive adhesive composition was coated on a surface of a poly(ethylene terephthalate) (PET) film (thickness: 38 m, MRF-38, Mitsubishi) treated with releasing treatment with a silicon compound to have a dry thickness of 25 m, and the resulting film was dried in an oven at 110 C. for 3 minutes. Then, the releasing-treated surface of the releasing-treated PET film (thickness: 38 m, MRF-38, Mitsubishi) was further laminated on the dried coating layer, and UV rays were radiated under the following conditions, thereby forming a second pressure-sensitive adhesive layer. Tensile modulus (at 25 C.) of the formed second pressure-sensitive adhesive layer was 0.2 MPa

(25) <Conditions for UV Radiation>

(26) UV Radiation Tool: High Pressure Mercury Lamp

(27) Radiation Conditions: Luminance: 600 mW/cm.sup.2 Intensity of Radiation: 150 mJ/cm.sup.2

(28) Preparing Polarizing Plate

(29) A double-layered pressure-sensitive adhesive layer was formed by laminating the first and second pressure-sensitive adhesive layers formed above using a laminator, and a polarizing plate was formed using the pressure-sensitive adhesive layer. The sequence of forming the polarizing plate was as follows. First, a polarizer was formed by elongating a polyvinylalcohol-based resin film, staining the film with iodine, and treating the resulting film with a boric acid aqueous solution. Subsequently, a 60 m-thick acryl film (formed by extruding and elongating a mixture including a phenoxy resin, polystyrene and polymethylmethacrylate) as a protective film was laminated on one surface of a polarizer formed by elongating a polyvinylalcohol-based resin film, dying the film with iodine and treating the film with a boric acid aqueous solution using the prepared adhesive composition (A). Afterward, the adhesive composition (A) was used having a thickness after curing of 5 m during lamination. In addition, the adhesive composition (A) was coated on a surface of the polarizer to which the acryl film was not attached to have a thickness after curing of 5 m. A polarizing plate was formed by laminating the first pressure-sensitive adhesive layer of the double-layered pressure-sensitive adhesive layer by means of a coating layer of the coated adhesive composition (A), and curing the coating layer by UV radiation under the following conditions (the structure of the polarizing plate: acryl film.fwdarw.active energy beam-curable adhesive layer.fwdarw.polarizer.fwdarw.active energy beam-curable adhesive layer.fwdarw.first pressure-sensitive adhesive layer second pressure-sensitive adhesive layer PET releasing film). UV radiation may be performed to a side of the acryl film, a side of the double-layered pressure-sensitive adhesive layer or the both sides.

(30) <Conditions for UV Radiation>

(31) UV Radiation Tool: High Pressure Mercury Lamp

(32) Radiation Conditions: Luminance: 800 mW/cm.sup.2 Intensity of Radiation: 2,000 mJ/cm.sup.2

Example 2

(33) A polarizing plate was formed as described in Example 1, except that a TAC film having a thickness of 60 m was used as a protective film instead of the acryl film.

Example 3

(34) A polarizing plate was formed as described in Example 1, except that lamination conditions were controlled such that the adhesive composition was coated to have a thickness after curing of 10 m.

Example 4

(35) A polarizing plate was formed as described in Example 1, except that lamination conditions were controlled such that the adhesive composition was coated to have a thickness after curing of 20 m.

Example 5

(36) A polarizing plate was formed as described in Example 1, except that the adhesive composition was coated to have a thickness after curing of 0.15 m.

Example 6

(37) A polarizing plate was formed as described in Example 1, except that the adhesive composition (B) was used as an adhesive composition.

Example 7

(38) A polarizing plate was formed as described in Example 1, except that the adhesive composition (C) was used as an adhesive composition.

Example 8

(39) A polarizing plate was formed as described in Example 1, except that the adhesive composition (D) was used as an adhesive composition.

Example 9

(40) A polarizing plate was formed as described in Example 1, except that the adhesive composition (E) was used as an adhesive composition.

Example 10

(41) A polarizing plate was formed as described in Example 1, except that the adhesive composition (F) was used as an adhesive composition.

Example 11

(42) A polarizing plate was formed as described in Example 1, except that the adhesive composition (G) was used as an adhesive composition.

Comparative Example 1

(43) A polarizing plate was formed as described in Example 1, except that the first pressure-sensitive adhesive layer was formed to have a thickness of 5 m, and the second pressure-sensitive adhesive layer was formed to have a thickness of 3 m in the formation of the pressure-sensitive adhesive layer.

Comparative Example 2

(44) A polarizing plate was formed as described in Example 1, except that lamination conditions were controlled such that the adhesive composition was coated to have a thickness after curing of 0.08 m.

Comparative Example 3

(45) A polarizing plate was formed as described in Example 1, except that lamination conditions were controlled such that the adhesive composition was coated to have a thickness after curing of 32 m.

Comparative Example 4

(46) A polarizing plate was formed as described in Example 1, except that a TAC film having a thickness of 60 m was used as a protective film instead of the acryl film, a water-based polyvinylalcohol-based adhesive composition generally used to attach a protective film, as an adhesive attaching the TAC film to the polarizer, was coated to have a dry thickness of 0.1 m, the water-based polyvinylalcohol-based adhesive composition was coated, the protective film was laminated and dried in an oven at 80 C. for 5 minutes, and the double-layered pressure-sensitive adhesive layer was laminated using the active energy beam-curable adhesive composition.

Comparative Example 5

(47) A polarizing plate was formed as described in Comparative Example 1, except that the adhesive composition (H) was used as an adhesive composition.

Comparative Example 6

(48) A polarizing plate was formed as described in Comparative Example 1, except that the adhesive composition (I) was used as an adhesive composition.

Comparative Example 7

(49) A polarizing plate was formed as described in Comparative Example 1, except that the adhesive composition (J) was used as an adhesive composition.

(50) <Evaluation of Physical Properties>

(51) 1. Evaluation of Tensile Modulus

(52) Herein, tensile modulus of a pressure-sensitive adhesive layer was measured by a stress-strain test due to tensile according to a method defined in ASTM D638, or when it was difficult to directly measure the tensile modulus, a storage modulus was measured and then converted into the tensile modulus by the following Conversion Formula. In detail, a sample having a stacked structure having a PET releasing film (thickness: 38 m, MRF-38), a pressure-sensitive adhesive layer and a PET releasing film (thickness: 38 m, MRF-38), which was formed in Example or Comparative Example, was cut into a dog bone-type specimen in the size of 7 cm (length)1 cm (width), both ends of the specimen were fixed with jigs for a tensile test, and tensile modulus was measured according to ASTM D638. The conditions for measuring the tensile modulus were as follows.

(53) <Conditions for Measuring Tensile Modulus>

(54) Measuring Apparatus: Universal Testing Machine (UTM)

(55) Equipment Model: Zwick Roell Z010, Instron

(56) Measurement Conditions: Load Cell: 500 N Tensile Rate: 3 mm/sec

(57) <Measurement of Storage Modulus and Conversion into Tensile Modulus>

(58) A pressure-sensitive adhesive layer was cut into 5 pieces in the size of 15 cm25 cm25 m (widthlengththickness), and the cut pieces were stacked in five layers. Subsequently, the stacked pressure-sensitive adhesive layers were cut in a circle having a diameter of 8 mm, and pressed using glasses overnight to enhance wettability at an interface between the layers, thereby removing air bubbles generated during stacking. As a result, a sample was prepared. Subsequently, the sample was placed on a parallel plate, and a gap was adjusted. Then, after Normal & Torque was adjusted to zero, and stabilization of normal force was checked, a storage modulus was measured under the following conditions, and the tensile modulus was calculated according to the following Expression.

(59) Measurement Apparatus and Measuring Conditions

(60) Measurement Apparatus: ARES-RDA, TA Instruments Inc. with forced convection oven

(61) Measuring Conditions:

(62) Geometry: 8 mm parallel plate

(63) Gap: around 1 mm

(64) Test Type: dynamic strain frequency sweep

(65) Strain=10.0 [%], temperature: 30 C.

(66) Initial Frequency: 0.4 rad/s, final frequency: 100 rad/s

(67) <Conversion Formula>
E=3G

(68) In Conversion Formula, E is a tensile modulus, and G is a storage modulus.

(69) 2. Evaluation of Durability and Reliability

(70) A sample was prepared by attaching a specimen prepared by cutting a polarizing plate in the size of 180 mm250 mm (widthlength) to a 19-inch panel commercially available using a laminator. Pressure applied in attachment was approximately 5 Kg/cm.sup.2, and the attachment was performed in a clean room to prevent generation of bubbles or impurities at an interface between the specimen and the panel. Afterward, the panel was compressed in an autoclave (50 C. and 5 atm) for approximately 30 minutes, and then stored under a constant temperature and humidity condition (23 C. and relative humidity: 50%) for 24 hours. Subsequently, the formed sample was left under conditions of a temperature of 60 C. and relative humidity of 90% for 100 hours, followed by the evaluation of humidity and thermal resistance by observing whether bubbles or peeling were or were not generated at the pressure-sensitive adhesive interface. In addition, the formed sample was left under conditions of a temperature of 90 C. for 100 hours, followed by the evaluation of thermal resistance by observing whether bubbles or peeling were or were not generated at the pressure-sensitive adhesive interface. The formed sample was left at room temperature for 24 hours right before the evaluation of humidity and thermal resistance or thermal resistance. Evaluation conditions were as follows:

(71) <Criteria for Evaluation of Durability and Reliability>

(72) : No air bubbles and peeling were generated.

(73) : Air bubbles and/or peeling were somewhat generated.

(74) X: Air bubbles and/or peeling were considerably generated.

(75) 3. Evaluation of Water Resistance

(76) A sample was prepared by attaching a specimen prepared by cutting a polarizing plate in the size of 180 mm130 mm (widthlength) to a glass substrate (soda lime glass). Subsequently, the formed sample was put into water at 60 C., left for 24 hours, and observed for bubbles or peeling to evaluate water resistance according to the following criteria. The formed sample was left at room temperature for 24 hours right before the evaluation of water resistance. The evaluation conditions were as follows:

(77) <Criteria for Evaluation of Water Resistance>

(78) : No air bubbles and peeling were generated at an interface between the adhesive layer and the pressure-sensitive adhesive layer.

(79) : Some bubbles and/or peeling were generated at an interface between the adhesive layer and the pressure-sensitive adhesive layer.

(80) X: Bubbles and/or peeling were considerably generated at an interface between the adhesive layer and the pressure-sensitive adhesive layer.

(81) 4. Evaluation of Thermal Shock Resistance

(82) A sample was prepared by attaching a specimen prepared by cutting a polarizing plate in the size of 100 mm100 mm (widthlength) to a glass substrate (soda lime glass). Subsequently, the formed sample was compressed in an autoclave at 50 C and 5 atm for 30 minutes and put in a thermal shock chamber, followed by the evaluation of physical properties. Thermal shock resistance was evaluated by repeating a process of leaving the compressed sample at 30 C. for 30 minutes and leaving the sample at 70 C. for 30 more minutes 100 cycles, and observing whether cracks were generated in an MD direction of a polarizer. The evaluation was performed according to the following criteria:

(83) <Criteria for Evaluating Thermal Shock Resistance>

(84) : No cracks of the polarizer were generated in the cutting part of the polarizing plate.

(85) : Many cracks of the polarizer 10 mm or less in size were generated in the cutting part of the polarizing plate.

(86) X: Many cracks of the polarizer 100 mm or more in size were generated overall in the MD direction of the polarizer.

(87) 5. Evaluation of Curling Characteristic

(88) Curling characteristics were evaluated according to the following criteria by laminating a protective film cut in the size of 130 mm180 mm (width (transverse direction (TD))length (MD direction)) with a polarizer using an adhesive composition during an operation of forming a polarizing plate, and measuring curling occurring in the TD direction during radiation with UV rays or drying when a water-based polyvinylalcohol-based adhesive was used. The measurement of curling was performed by the method illustrated in FIG. 4.

(89) <Evaluation Criteria>

(90) : Curling occurring in the TD direction was less than 0.5 cm.

(91) : Curling occurring in the TD direction was 0.5 cm to 2.0 cm

(92) X: Curling occurring in the TD direction was more than 2.0 cm

(93) 6. Evaluation of Weight Average Molecular Weight and Distribution of Molecular Weight

(94) The weight average molecular weight and the distribution of the molecular weight of an acryl polymer were measured using GPC under the following conditions. To draw a calibration curve, standard polystyrene of an Agilent system was used, and measurement results were converted.

(95) <Conditions for Measuring Weight Average Molecular Weight>

(96) Measuring Apparatus Agilent GPC (Agilent 1200 series, USA)

(97) Column: two connected PL mixed B

(98) Column Temperature: 40 C.

(99) Eluent: Tetrahydrofuran

(100) Flow Rate: 1.0 mL/min

(101) Concentration: 2 mg/mL (100 L injection)

(102) 7. Evaluation of Adhesion Uniformity

(103) Adhesion uniformity was evaluated by distinguishing flat exterior as from curved exterior as X.

(104) The evaluation results are summarized and listed in Tables 2 and 3.

(105) TABLE-US-00002 TABLE 2 Example 1 2 3 4 5 6 7 8 9 10 11 Kind of Acryl TAC Acryl Acryl Acryl Acryl Acryl Acryl Acryl Acryl Acryl Protective Film Thickness 5 5 10 20 0.15 5 5 5 5 5 5 of Adhesive Layer (m) Curing UV UV UV UV UV UV UV UV UV UV UV Type for Rays Rays Rays Rays Rays Rays Rays Rays Rays Rays Rays Adhesive Kind of hybrid hybrid hybrid hybrid hybrid hybrid hybrid hybrid hybrid hybrid cationic Adhesive Composition A A A A A B C D E F G of Adhesive Tg( C.) 52 52 52 52 52 54 61 69 80 97 112 Thickness 50 50 50 50 50 50 50 50 50 50 50 of Pressure- Sensitive Adhesive Layer (m) Thermal Resistance Humidity & Thermal Resistance Water Resistance Thermal Shock Resistance Adhesion Uniformity Curling Characteristic

(106) TABLE-US-00003 TABLE 3 Comparative Example 1 2 3 4 5 6 7 Kind of Acryl Acryl Acryl TAC Acryl Acryl Acryl Protective Film Thickness 5 0.08 32 0.1 5 5 5 of Adhesive Layer (m) Curing UV Rays UV Rays UV Rays Water- UV Rays UV Rays UV Rays Type based for drying Adhesive and curing Kind of hybrid hybrid hybrid hybrid hybrid hybrid radical Adhesive Composition A A A Water- H I J of Adhesive based Tg( C.) 52 52 52 90 25 40 24 Thickness 8 50 50 50 8 8 8 of Pressure- Sensitive Adhesive Layer (m) Thermal x x x x x Resistance Humidity & Thermal Resistance Water x Resistance Thermal x x x x x Shock Resistance Adhesion x x Uniformity Curling x Characteristic