TW201732328A - Composite polarizing plate and image display device including the same - Google Patents

Abstract

The present invention provides a composite polarizing plate including: a polarizer; and a composite retardation layer which is disposed on at least one surface of the polarizer in such a way that a first retardation layer, a photo-curable adhesive layer and a second retardation layer are laminated in this order from the polarizer, wherein the composite retardation layer has a gradient of -514 to -275 for a temperature of a stiffness within a range of 20 to 90 DEG C, and an image display device including the above-described composite polarizing plate. Thereby, the composite polarizing plate has improved bending properties of a display, and adhesive properties between the retardation layers, and exhibits excellent light leakage properties due to an improvement in stiffness and bending properties of the composite retardation layer.

Description

Composite polarizing plate and display device including the same

The present invention relates to a composite polarizing plate and an image display device including the same.

In line with information display terminal devices such as mobile phones and PDAs, the trend of information display has progressed toward mobility and convenience centering on high performance and high functionality capable of actually presenting objects. Therefore, there is a large demand for flexible displays that are lightweight and easy to fold and thus have no space and shape limitations.

More particularly, a flexible display refers to a display made using a flexible substrate that can be bent or folded, and can be classified into a rough display, a flexible display, a rollable display depending on its use and function. In addition, the flexible display is an evolving display, thus replacing the existing flat panel display (FDP) with a thin and flexible substrate, such as a film for a liquid crystal display (LCD) or an organic light emitting diode (OLED). Transistor (TFT) device substrates, color filter substrates, substrates for touch screen panels, and heavy and brittle glass plates for substrates used in solar cells, and are available in a variety of applications for space and shape limitations. Application. Finally, about The continuous research and development of flexible displays is moving forward toward the commercialization of paper-like displays that can be distorted.

The flexible substrate used in such a flexible display is formed in a multilayer structure. Therefore, in order to bond the retardation layers included in the multilayer structure to each other, a pressure-sensitive adhesive is used. At the same time, the flexible substrate is often bent during use, and if the adhesion between the retardation layers is weak, there is a problem that the adhesive layer is expanded or the retardation layer is peeled off.

For example, Korean Patent Registration No. 1191865 discloses a related art of a flexible substrate, but does not propose a solution to the aforementioned problems.

Accordingly, it is an object of the present invention to provide a composite polarizing plate having improved bending properties of the display and adhesion properties between the retardation layers.

Further, another object of the present invention is to provide a composite polarizing plate having excellent light leakage properties exhibited by the improvement of the rigidity and bending properties of the composite retardation layer.

Further, another object of the present invention is to provide an image display apparatus including the composite polarizing plate described above.

The foregoing objects of the present invention will be achieved by the following characteristics:

(1) A composite polarizing plate comprising: a polarizer; and a composite retardation layer disposed on at least one surface of the polarizer such that the first phase difference layer and the light curable adhesive layer The layer and the second phase difference layer are laminated from the polarizer in such a order, wherein the composite phase difference layer is in the range of 20 ° C to 90 ° C The temperature within the stiffness has a gradient of -514 to -275.

(2) The composite polarizing plate according to (1) above, wherein the first retardation layer is a λ/2 retardation layer, and the second retardation layer is a λ/4 retardation layer.

(3) The composite polarizing plate according to (1) above, wherein the photocurable adhesive of the photocurable adhesive layer comprises a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound.

(4) The composite polarizing plate according to (3) above, wherein the weight ratio of the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound included in the photocurable adhesive is 1:1.5 to 4 .

(5) The composite polarizing plate according to (3) above, wherein the cycloaliphatic epoxy compound is 3,4-epoxycyclohexylmethyl or 3,4-epoxycyclohexanecarboxylate.

(6) The composite polarizing plate according to (3) above, wherein the linear aliphatic epoxy compound is at least one selected from the group consisting of neopentyl glycol diglycidyl ether, 1,2,7,8-dicyclooxyoctane, 1,4-butanediol diglycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxy-9-pinene and 2 , 3-epoxy-1-(1-ethoxyethoxy)propane.

(7) The composite polarizing plate according to (1) above, wherein the photocurable adhesive layer has a coating thickness of from 0.01 μm to 5 μm.

(8) The composite polarizing plate according to (1) above, wherein the composite retardation layer has a thickness of from 2 μm to 7 μm.

(9) The composite polarizing plate according to (1) above, wherein the polarizer comprises a polarizing film, or a base film, and a polarizing coating film on the base film.

(10) The composite polarizing plate according to (1) above, wherein the composite phase difference layer is disposed on one surface of the polarizer, and the protective film is adhered to the bias The other surface of the light mirror.

(11) An image display device comprising the composite polarizing plate according to any one of (1) to (10) above.

According to the composite polarizing plate of the present invention, it is possible to improve the bending property of the display and the adhesion property between the retardation layers.

Further, the composite polarizing plate according to the present invention may have excellent light leakage properties exhibited by the improvement of the bending property by reducing the expansion ratio caused by the rigidity improvement of the composite retardation layer.

Further, the composite polarizing plate according to the present invention may reduce the defect rate of the product because there is no need to tear off the process of separating the film during the manufacturing process.

Further, the present invention can provide an image display apparatus including the composite polarizing plate described above.

The above and other objects, features and other advantages of the present invention will become more apparent from Figure.

Fig. 2 is a schematic cross-sectional view showing a composite polarizing plate according to a specific example of the present invention.

The present invention discloses a composite polarizing plate comprising: a polarizing mirror; and a composite retardation layer disposed on at least one surface of the polarizing mirror such that the first retardation layer, the photocurable adhesive layer and the second retardation layer The laminate is laminated in the order of the polarizer having a gradient of -514 to -275 for a temperature within a range of 20 ° C to 90 ° C, and an image display device including the composite polarizing plate. Therefore, the composite polarizing plate has improved bending properties of the display, adhesion between the retardation layers, and improved rigidity and bending properties of the composite retardation layer, thereby exhibiting excellent light leakage properties.

Hereinafter, specific specific examples of the present invention will be described with reference to the drawings. However, these are merely examples, and the invention is not limited thereto.

<Composite polarizing plate>

The composite polarizing plate of the present invention comprises a polarizing mirror and a composite retardation layer disposed on at least one surface of the polarizing mirror.

Polarizer

The polarizer can use a polarizer typically used in the related art, and the type thereof is not particularly limited. For example, the polarizing performance can be applied to the polarizing film as a film through a single polarizing film itself, and can be applied in a coating form through a polarizing coating film formed on the base film.

More specifically, the polarizer may be any polarizer obtained by swelling, dyeing, crosslinking, stretching, washing, and drying to form a film including a polarizer of a resin for forming a polarizer. Further, the polarizer can be obtained by coating a composition containing a resin for forming a polarizer on a base film to prepare a polarizing film, and stretching, dyeing, crosslinking, washing, and drying the laminated film.

The type of the resin used to form the polarizing film used in the aforementioned polarizing film or polarizing coating film is not particularly limited as long as it may be a dichroic color The material may be dyed such as iodine, and may include, for example, polyvinyl alcohol resin, dehydrated polyvinyl alcohol resin, dehydrochlorinated polyvinyl alcohol resin, polyethylene terephthalate resin, ethylene vinyl acetate. A copolymer resin, an ethylene-vinyl alcohol copolymer resin, a cellulose resin, and/or a partially saponified resin thereof, or the like. Among these resins, a polyvinyl alcohol resin is preferably used as a resin for forming a polarizer in terms of excellent uniformity of polarization in a plane and excellent dyeing affinity for a dichroic material such as iodine.

The thickness of the film for forming the polarizer or the thickness of the film obtained by coating the resin for forming the polarizer is not particularly limited. For example, the film for forming the polarizer may have a thickness of 10 μm to 150 μm, and the polarizing coating film formed by coating a composition containing a resin for forming a polarizer on the base film may have 3 μm to 30 μm. The thickness.

Further, according to the composite polarizing plate of the specific example of the present invention, in addition to the polarizer, an optical film capable of exhibiting polarization characteristics by coating a liquid crystal thereon may be used.

Composite phase difference layer

The composite phase difference layer according to the present invention is disposed on at least one surface of the polarizer. The composite retardation layer and the polarizer may be directly bonded to each other, and may further include a separate layer therebetween, and may further include protection therebetween.

Further, the composite retardation layer according to the present invention is formed in such a manner that the first retardation layer, the photocurable adhesive layer, and the second retardation layer are laminated from the polarizer in this order.

The composite retardation layer according to the present invention is directed to 20 ° C to 90 The temperature of the stiffness within the °C range has a gradient of -514 to -275.

As described above, the first phase difference layer and the second phase difference layer are used in an OLED display, and when the layers are used in a flexible display, excellent bending properties are required.

Conventionally, the laminate of the first retardation layer and the second retardation layer has creases due to insufficient bending properties, and problems of interlayer peeling, defect appearance or deformation, and cracks.

In this regard, the present invention describes a composite phase difference layer in which the first phase difference layer and the second phase difference layer are adhered to each other by a photocurable adhesive, and is provided within a specific temperature range of the composite phase difference layer - A rigid phase gradient composite layer of 514 to -275, thus solving the aforementioned problems.

Further, when a pressure-sensitive adhesive is used to bond the first retardation layer and the second retardation layer to each other, a release film (carrier film) is used. In this case, the introduction of foreign matter may cause a failure due to static electricity generated during the process of tearing off the release film.

However, the composite phase difference layer according to the present invention uses a photocurable adhesive layer, making it possible to reduce the defect rate of the product because the process of tearing off the release film is not required in the process. Further, since the photocurable adhesive can have sufficient adhesive strength even when formed to be thinner than the pressure-sensitive adhesive layer, the composite polarizing plate can be formed with a reduced thickness, and thus the bending property is improved.

In addition, the magnitude of adhesion strength, heat resistance, durability, and temperature gradient against temperature can be controlled by controlling the light according to the present invention. The composition and content of the adhesive layer are controlled.

If the stiffness gradient is less than -514, creases occur, as well as interlayer peeling, defect appearance or deformation. If the stiffness gradient exceeds -275, cracks occur.

The thickness of the composite retardation layer is not particularly limited and may be, for example, 2 μm to 7 μm. In this case, the bending property and the adhesive property between the retardation layers can be improved. Preferably, the composite retardation layer according to the present invention is designed to have a rigid gradient of -514 to -275 within a temperature range of 20 ° C to 90 ° C of the composite retardation layer.

The composite retardation layer according to the present invention can be bonded to a polarizing mirror by any means known in the art, and, for example, a pressure-sensitive adhesive or an adhesive can be used, and an adhesive is preferably used.

Phase difference layer

According to the first phase difference layer and the second phase difference layer of the present invention, the photocurable adhesive layer is interposed therebetween to be bonded.

The first phase difference layer and the second phase difference layer may respectively use phase difference layers known in the related art. For example, the first retardation layer and the second retardation layer may be a stretched polymer film or a non-stretched polymer film, or a liquid crystal layer obtained by curing a reactive liquid crystal compound. More specifically, the first phase difference layer may be a λ/2 phase difference layer, and the second phase difference layer may be a λ/4 phase difference layer.

For example, when the first retardation layer and the second retardation layer are formed into a liquid crystal layer, the reactive liquid crystal compound (RM) can be used as a liquid crystal layer having optical anisotropy and crosslinkability due to light or heat. And may include capital The compound described in Information Display 10 [1] (Recent Research Trend in Reactive Liquid Crystal Monomer (RM)).

The liquid crystal compound may be coated on the base film to form a liquid crystal film, and the coating method is not particularly limited, and may include a spin coating method, a roll coating method, a dispensing coating method, a gravure coating method, and the like. Preferably, the type and amount of the solvent are determined depending on the coating method.

The type of the base film is not particularly limited and may include any of the protective films which will be described later.

Photocurable adhesive layer

The photocurable adhesive layer according to the present invention is used in a portion required for bonding the first retardation layer and the second retardation layer of the composite retardation layer.

If desired, the photocurable adhesive layer according to the present invention can be further applied between the polarizer and the protective substrate or between the protective substrate and the composite retardation layer.

The photocurable adhesive layer according to the present invention can be made of a photocurable adhesive composition capable of photocurable bonding. Herein, the photocurable adhesive composition can be used without particular limitation as long as it can be photocurable. For example, the photocurable adhesive composition may include a photopolymerizable compound, a photoinitiator, and the like.

The photopolymerizable compound may be a photoradical polymerizable compound or a photocationic polymerizable compound. These compounds may be used singly or in combination of two or more thereof.

As an example of the photoradical polymerizable compound, the photoradical polymerizable compound exemplified in the paragraph [0100] of Korean Patent Laid-Open Publication No. 2015-0017446 can be used.

Further, a polymer polymerized by the aforementioned monomer can be used as a photoradical polymerizable compound.

For the photocationic polymerizable compound, the photocationic polymerizable compound exemplified in paragraph [0101] of Korean Patent Laid-Open Publication No. 2015-0017446 can be used as an example of a photocationic polymerizable compound.

Preferably, in accordance with a specific example of the present invention, the photocurable adhesive composition includes a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound in terms of controlling the adhesive property and the rigid orientation.

By controlling the weight ratio of the content of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound, it is possible to more easily improve the adhesion and control rigidity between the first retardation layer and the second retardation layer. In this aspect, it is preferred that the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is in the range of 1:1.5 to 1:4, and more preferably, it is selected from 1:2 to 1:4. range. Within the above range, the improved adhesion property between the retardation layers, the improvement from the interlaminar tear and the improvement in rigidity lead to an improvement in bending properties, and may have excellent light leakage properties.

In this case, the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound are not particularly limited, and, for example, the cycloaliphatic epoxy compound may be 3,4-epoxycyclohexylmethyl or 3,4-Ethoxycyclohexanecarboxylate.

The linear aliphatic epoxy compound may be at least one selected from the group consisting of neopentyl glycol diglycidyl ether and 1,2,7,8-dicyclooxyoctane. , 1,4-butanediol diglycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxy-9-pinene and 2,3-epoxy-1-(1-ethoxyl) Ethyl ethoxy) propane.

Further, if necessary, the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound may further include a photoradical polymerizable compound and a photocationic polymerizable compound as described above. Preferably, the content of such polymerizable compounds is in the range of from 1% to 20% by weight.

Further, as an example of the description of the photocationic polymerizable compound, the photopolymerization initiator content, and the coating method of the photocurable adhesive composition, the use of Korean Patent Laid-Open Publication No. 2015-0017446 Description of paragraphs [0102] to [0104].

The coating thickness of the photocurable adhesive composition is not particularly limited, and, for example, the photocurable adhesive composition is applied in a thickness of from 0.01 μm to 5 μm, and preferably from 0.5 μm to 3 μm.

If the coating thickness of the photocurable adhesive composition exceeds 5 μm, it may be applied to a polarizing plate of a typical display, but when evaluating the bending property of the flexible display, cracks may occur in the protective substrate.

Protective film

The protective film can be adhered to at least one surface of the polarizer. For example, when the composite phase difference layer is disposed on one surface of the polarizer, the protective film can be adhered to the other surface of the polarizer. Further, the protective film may be disposed between the composite retardation layer and the polarizer, but is not limited thereto.

The description of paragraphs [0111] to [0114] in Korean Patent Laid-Open Publication No. 2015-0017446 can be used as an embodiment of a protective film and a description thereof.

Further, as for the thermosetting resin or the UV curable resin, an aryl resin, a urethane resin, an acrylonitrile-urethane resin, an epoxy resin, a polyoxymethylene resin or the like may be used to form a cured layer. However, it is not limited to a specific film, and in consideration of adhesiveness or durability, any of the above resins may be conveniently used.

The thickness of the protective film is not particularly limited, but may be, for example, 10 μm to 200 μm, and preferably 10 μm to 150 μm. When the protective film has a thickness of 10 μm to 200 μm, if the polarizer protective film is laminated on both surfaces of the polarizer, the individual protective films may have the same or different thicknesses from each other.

<Image display device>

Further, the composite polarizing plate of the present invention can be effectively applied to an image display device by being combined with other conventional components.

As the image display device, for example, a typical liquid crystal display device can be used, and in addition, an electroluminescence display device, a plasma display device, an electroluminescence light emission display device, an OLED, or the like can be used. When the composite polarizing plate of the present invention is applied to an OLED, preferably, the polarizer side is disposed on the visible side.

In the following, preferred embodiments are presented to more specifically describe the invention. However, the following examples are only intended to illustrate the invention, and it is obvious to those skilled in the art that various changes and modifications can be made within the scope and spirit of the invention. These changes and modifications are properly covered by the accompanying patent application. range.

Preparation Example 1

A polyvinyl alcohol film (PS 7500, Kuraray Co.) having a thickness of 75 μm, an average degree of polymerization of 2,400, and a degree of saponification of 99.9% or more is immersed in water (deionized water) at 30 ° C It lasted for 2 minutes to swell. Thereafter, the film was immersed in a cross-linking liquid containing 3.5 mmol/L of iodine and 2 wt.% of potassium iodide, and dyed at 30 ° C for 4 minutes. Next, the treated film is further immersed in a cross-linking liquid containing 2 wt.% of potassium iodide, 3.7 wt.% of boric acid, and lithium chloride of 4.5 mol% with respect to 1 mol of potassium iodide, at 50 ° C for 2 minutes. To cross-link. During individual swelling/dyeing/crosslinking/washing treatments, the polyvinyl alcohol film was prepared by stretching to a cumulative stretch ratio of 5.5.

Preparation Example 2

Noblen FLX80E4 resin (Sumitomo Chemical Co., Ltd.) placed on both sides of the resin layer of Nobelland W151 (Sumitomo Chemical Co., Ltd.), and the preparation method of the base film having a three-layer structure The co-extrusion molding was carried out using a multilayer extrusion molding machine, and then Z-200 polyvinyl alcohol powder (Japan Synthetic Chemical Co., Ltd.) was heated at 90 ° C to prepare a 3 wt.% aqueous solution. Thereafter, a resin (Sumirejin) 650 (Taoka Chemical Co., Ltd.) as a crosslinking agent was mixed at a ratio of 1 wt.% to 2 wt.% of polyvinyl alcohol powder to obtain a coating for forming a primer layer. The coating liquid and the polyvinyl alcohol powder of PVA 124 (Kuraray) were heated at 90 ° C to obtain an 8 wt.% aqueous solution, and thus a coating liquid for forming a polyvinyl alcohol resin was prepared. Second, more The base film was subjected to corona treatment, the bottom layer was coated on the corona-treated surface using a micro gravure coating machine, and dried at 80 ° C for 3 minutes to form a 0.2 μm bottom layer, and then the polyvinyl alcohol coating liquid was continuously It was applied to the underlayer and dried at 90 ° C for 5 minutes to form a polyvinyl alcohol resin layer having a thickness of 10 μm.

The obtained multilayer film was subjected to 5.8-fold stretching at 160 ° C by a hot roller, and immersed in pure water at 60 ° C for 1 minute and immersed in an iodine and potassium iodide dyeing solution for 3 minutes to be dyed. Then, the multilayer film was immersed in a crosslinking solution containing boric acid and potassium iodide at 75 ° C for 10 minutes, and washed with pure water at 10 ° C and dried at 80 ° C for 5 minutes to prepare a polyvinyl alcohol polarizer having a thickness of 3.8 μm.

Example 1

(A) Preparation of photocurable adhesive composition

By adding 20 wt.% of CEL 2021P (Daicel Co.) as a cycloaliphatic epoxy compound, 80 wt.% of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Asian Aldrich Co., 4 wt.% of CPI-110A (San-Apro Co.) as a cationic photoinitiator, to prepare an adhesive composition. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

(B) Preparation of composite retardation layer

The prepared photocurable adhesive composition is adhered between the λ/2 retardation layer and the λ/4 retardation layer, thereby forming a thickness of 3 μm therebetween, and using a high pressure mercury lamp (UVA at 500 mJ/cm ² ) The integrated light amount was subjected to UV curing thereon, and thus a composite retardation layer was prepared.

(B) Preparation of polarizing plate

The triethylenesulfonated cellulose film (Fuji Co.) was adhered to one surface of the polarizing lens prepared in Preparation Example 1 by applying an aqueous adhesive and dried, and λ/2 of the composite retardation layer The phase difference layer side was bonded to the other surface using an acrylic pressure-sensitive adhesive. The film type acrylic pressure-sensitive adhesive was further bonded to the λ/4 phase difference layer as configured above, and thus a polarizing plate was prepared.

In Fig. 2, a cross-sectional view of a composite polarizing plate is schematically illustrated.

Example 2

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared by mixing 30 wt.% of CEL 2021P (Dyson) and 70 wt. as a cycloaliphatic epoxy compound. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:2.3.

Example 3

The polarizing plate was produced according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by separately mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound, and 70 wt.% of neopentyl glycol diglycidyl ether and 10% by weight of 1,2,7,8-dicyclooxyoctane (Alysin) as a linear aliphatic epoxy compound. In this case, a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound The weight ratio is 1:4.

Example 4

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound and 80%. Wt.% as a linear aliphatic epoxy compound 1,2,7,8-dicyclooxyoctane (Ali). In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 5

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound and 80%. Wt.% of 1,4-butanediol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 6

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound and 80%. Wt.% 2-ethylhexyl glycidyl ether (Ali) which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 7

The polarizing plate is according to the same procedure as described in Embodiment 1. Manufactured, but the adhesive composition was prepared by mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound and 80% by weight of a linear aliphatic epoxy compound. 1,2-Epoxy-9-pinene (Ali). In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 8

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound and 80%. Wt.% of 2,3-epoxy-1-(1-ethoxyethoxy)propane (Alicone) as a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 9

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyce), which is a cycloaliphatic epoxy compound, 70 wt. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound, and 10 wt.% of an aromatic epoxy compound, a hydroquinone diglycidyl ether (Ali) the company). In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:3.5.

Example 10

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyce), which is a cycloaliphatic epoxy compound, 70 wt. % As a linear aliphatic epoxy compound, neopentyl glycol diglycidyl ether (Ali), 10 wt.% of glycidyl methacrylate (Ali), which is an aromatic acrylate monomer, And 4 wt.% of Irg 184 (Siba Co.) as a radical photoinitiator. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:3.5.

Example 11

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by mixing 20 wt.% of CEL 2021P (Dyce), which is a cycloaliphatic epoxy compound, 70 wt. % as a linear aliphatic epoxy compound neopentyl glycol diglycidyl ether (Ali), 10wt.% as an aromatic epoxy compound between benzenediol diglycidyl ether (Ali) 10 wt.% of glycidyl methacrylate (Alysin) as an aromatic acrylate monomer, and 4 wt.% of Ig 184 (Siba) as a radical photoinitiator. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:3.

Example 12

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive had a thickness of 5 μm.

Example 13

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive had a thickness of 1 μm.

Example 14

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the polarizing mirror prepared in Preparation Example 2 was used as a polarizing mirror, and a triethylenesulfonated cellulose film (Fuji Co., Ltd.) was bonded to one of the two surfaces of the polarizing mirror. On the side, a polyvinyl alcohol resin is formed thereon.

Comparative example 1

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows by mixing 10 wt.% of CEL 2021P (Dyson) and 90 wt. as a cycloaliphatic epoxy compound. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:9.

Comparative example 2

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared by mixing 70 wt.% of CEL 2021P (Dyson) and 30 wt. as a cycloaliphatic epoxy compound. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:0.4.

Comparative example 3

The polarizing plate was produced according to the same procedure as described in Example 1, except that the adhesive composition was prepared as follows: by separately mixing 70 wt.% of CEL 2021P (Dyson) as a cycloaliphatic epoxy compound, and 20 wt.% of neopentyl glycol diglycidyl ether and 10% by weight of 1,2,7,8-dicyclooxyoctane (Alysin) as a linear aliphatic epoxy compound. to In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:0.4.

Comparative example 4

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared by mixing 60 wt.% of CEL 2021P (Dyson) and 40 wt. as a cycloaliphatic epoxy compound. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:0.7.

Comparative Example 5

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive composition was prepared by mixing 50 wt.% of CEL 2021P (Dyson) and 50 wt. as a cycloaliphatic epoxy compound. % of neopentyl glycol diglycidyl ether (Ali), which is a linear aliphatic epoxy compound. In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:1.

Comparative Example 6

70 wt.% of butyl acrylate, 20 wt.% of methyl acrylate, and 10 wt.% of acrylic polymerized acrylic copolymer, and 15 wt.% of polyfunctional acrylate monomer, 0.3 wt.% as photopolymerization The initiator of Irgacure 500 (Ciba Chemical Co.), Colonate L (Nippon Polyurethane Industry Co.) as an isocyanate Crosslinking agent, and 0.1 wt.% of KBM-403 as a decane coupling agent (Xinyue Chemical Co., Ltd.) (Shinetsu Chemical Co.)) was added to the above acrylic copolymer, and thus an acrylic pressure-sensitive adhesive composition was prepared. The prepared acrylic pressure-sensitive adhesive composition was applied to a separation film having a thickness of 80 μm and dried to prepare an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm.

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the prepared pressure-sensitive adhesive layer was repeatedly transferred to the λ/2 retardation layer of the composite retardation layer to form an acrylic pressure-sensitive adhesive having a thickness of 20 μm. The layer, and the λ/4 phase difference layer are bonded thereto.

Comparative Example 7

The polarizing plate was fabricated according to the same procedure as described in Comparative Example 6, except that the acrylic pressure-sensitive adhesive layer had a thickness of 5 μm.

Comparative Example 7

The polarizing plate was fabricated according to the same procedure as described in Example 1, except that the adhesive layer had a thickness of 7 μm.

Rigid gradient measurement

The composite retardation layer prepared in the examples and the comparative examples was cut into a size of 2 mm x 50 mm, and then heated in the longitudinal direction by a dynamic thermal characteristic analyzer (Q-800, TA Instruments) by heating it from 30 ° C to 80 ° C. The distance of 15 mm is estimated to be rigid. At this time, the rigidity of 30 ° C, 50 ° C, and 80 ° C was selected to measure the gradient of rigidity. The gradient of stiffness is obtained from the graph, where the X-axis represents temperature (°C) and the Y-axis represents the magnitude of stiffness for each temperature, and the gradient of stiffness is calculated from linear regression analysis. The rigid gradients of Examples 1, 12 and 13 and Comparative Example 7 are shown in the temperature-rigidity diagram of Figure 1.

Evaluation test

(1) Evaluation of cross cutting

The composite polarizing plates prepared in the examples and the comparative examples were tested for interlayer adhesion (whether interlayer tearing occurred) according to the standard of ASTM D 3359. First, 11 cutting lines were drawn in the longitudinal direction and the lateral direction at intervals of 1 mm on the surface of the composite polarizing plate to form 100 layers of 1 mm ² area. Then, the process of attaching the celluloid tape to the surface and removing the tape from the surface was repeated three times, the average number of tears was counted, and the cross cut was evaluated according to the following criteria. The evaluation results are shown in Table 3 and Table 4 below.

OK: 0 or more occurrences, but less than 10 tears

NG: 10 or more tears

(2) Evaluation of light leakage

The prepared polarizing plate was bonded to the glass using a film type pressure-sensitive adhesive, and the silver reflecting plate was attached to the glass surface opposite to the surface on which the polarizing plate was bonded, and then the glass was introduced into an oven at 85 ° C for 24 hours and taken out. Thereafter, the light leakage of the polarizing plate was observed in a reflection mode in a dark room, and evaluated according to the following criteria. The evaluation results are shown in Table 3 and Table 4 below.

○: No light leakage occurred

X: Light leakage occurs

(3) Evaluation of bending

Use a bend tester (MIT evaluation) to have a width of 10mm Specimens of degree, 150 mm length and 3 mm radius were subjected to repeated bending tests. During the up to 50,000 repeated bending tests, the degree of cracking and the degree of tearing between the layers were observed and evaluated according to the following criteria. The evaluation results are shown in Table 3 and Table 4 below.

[crack]

○: no crack appeared

△: Cracks having a size of less than 2 mm appear at the end of the protective substrate

X: Cracks appear on all surfaces of the protective substrate

[Interlayer tearing]

○: no peeling between layers occurred

△: peeling off at the end of the protective substrate/adhesive protective substrate with a tear length of less than 2 mm

X: tearing off at the end of the protective substrate/adhesive protective substrate with a tear length of more than 2 mm

Referring to Tables 3 and 4, it can be seen that the composite retardation layers of all the examples show excellent evaluation results in cross-cutting, light leakage and bending evaluation, but some composite phase difference layers of the comparative example are in cross cutting, light leakage and bending. There are no excellent assessment results in the assessment.

Claims (11)

A composite polarizing plate comprising: a polarizer; and a composite phase difference layer disposed on at least one surface of the polarizer, such that the first phase difference layer, the photocurable adhesive layer and the second phase difference layer are The sorting is performed from the polarizer layer, wherein the composite retardation layer has a gradient of -514 to -275 for a temperature within a range of 20 ° C to 90 ° C. The composite polarizing plate of claim 1, wherein the first retardation layer is a λ/2 retardation layer, and the second retardation layer is a λ/4 retardation layer. The composite polarizing plate of claim 1, wherein the photocurable adhesive of the photocurable adhesive layer comprises a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound. The composite polarizing plate of claim 3, wherein the weight ratio of the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound included in the photocurable adhesive is 1:1.5. To 4. The composite polarizing plate of claim 3, wherein the cycloaliphatic epoxy compound is 3,4-epoxycyclohexylmethyl or 3,4-epoxycyclohexanecarboxylate. The composite polarizing plate according to claim 3, wherein the linear aliphatic epoxy compound is at least one selected from the group consisting of neopentyl glycol diglycidyl Ether, 1,2,7,8-dicyclooxyoctane, 1,4-butanediol diglycidyl ether, 2-ethylhexyl condensation Glycidyl ether, 1,2-epoxy-9-pinene and 2,3-epoxy-1-(1-ethoxyethoxy)propane. The composite polarizing plate of claim 1, wherein the photocurable adhesive layer has a coating thickness of 0.01 μm to 5 μm. The composite polarizing plate of claim 1, wherein the composite retardation layer has a thickness of from 2 μm to 7 μm. The composite polarizing plate of claim 1, wherein the polarizer comprises a polarizing film, or a base film, and a polarizing coating film on the base film. The composite polarizing plate according to claim 1, wherein the composite phase difference layer is disposed on one surface of the polarizer, and the protective film is adhered to the other surface of the polarizer. An image display device comprising the composite polarizing plate according to any one of claims 1 to 10.