WO2017099449A1 - Complex polarizing plate and image display device comprising same - Google Patents

Abstract

The present invention relates to a complex polarizing plate and, more specifically, to a complex polarizing plate comprising: a polarizer; and complex phase difference layers disposed on at least one surface of the polarizer, and having, from the polarizer, a first phase difference layer, a photocurable adhesive layer, and a second phase difference layer, which are stacked in order, wherein the complex phase difference layers have -514 to -275 of a slope of stiffness with respect to a temperature in the range of 20 to 90°C, thereby improving bending characteristics of a display and adhesive characteristics between phase difference layers, enhancing the stiffness of the complex phase difference layers, and improving the bending characteristics so as to exhibit good light leakage characteristics.

Description

Composite polarizing plate and image display device including the same

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

The development trend of information display is aimed at mobility and convenience in accordance with the mobility of information display terminals such as mobile phones and PDAs in the center of high-performance and high-functionality that shows things realistically, and thus frees from space and form constraints. The demand for flexible displays, which are light and easily foldable, is rapidly increasing.

Specifically, a flexible display is a display manufactured using a thin flexible substrate that can be bent or bent, and can be distinguished into a rugged display, a bendable display, and a rollable display according to a use and a function. Thin film transistor (TFT) element substrates for liquid crystal display (LCD) or organic EL display (OLED) substrates, color filter substrates, substrates for touch screen panels, and substrates for solar cells It is a display that is being developed to secure various applications from space and form constraints by replacing the heavy and fragile plate glass used in flat panel displays (FPD) with thin, flexible substrates. Ongoing research and development is aimed at commercializing paper-like displays.

The flexible substrate used in the flexible display forms a multilayer structure, and an adhesive is used for bonding between retardation layers included in the multilayer structure. On the other hand, the flexible substrate is often bent when used, if the bonding strength between the retardation layer is weak, problems such as expansion of the adhesive layer or peeling between the retardation layer occurs.

Korean Patent No. 1191865 discloses a technology related to a flexible substrate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite polarizing plate in which the bending property of a display and the adhesive property between retardation layers are improved.

In addition, an object of the present invention is to provide a composite polarizing plate in which the stiffness of the composite retardation layer is improved, the bending property is improved, and exhibits good light leakage characteristics.

In addition, the present invention can provide an image display device including the composite polarizing plate as described above.

1. polarizer; And a composite retardation layer disposed on at least one surface of the polarizer and stacked from the polarizer in order of a first retardation layer, a photocurable adhesive layer, and a second retardation layer, wherein the composite retardation layer is in a range of 20 to 90 ° C. Wherein the slope with respect to the temperature of the stiffness is from -514 to -275.

2. The composite polarizing plate of 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. In the above 1, wherein the photocurable adhesive comprises a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound, composite polarizing plate.

4. In the above 3, wherein the photocurable adhesive is a weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound of 1: 1.5 to 4, the composite polarizing plate.

5. In the above 3, wherein the cycloaliphatic epoxy compound is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate), a composite polarizing plate.

6. In the above 3, the linear aliphatic epoxy compound is neopentyl glycol diglycidyl ether (neopentyl glycol diglycidyl ether), 1,2,7,8-diepoxyoctane (1,2,7,8-Diepoxyoctane ), 1,4-Butanediol diglycidyl ether, 2-Ethyl Hexyl Glycidyl Ether, 1,2-Epoxy-9-decene (1) At least one selected from the group consisting of, 2-Epoxy-9-decene) and 2,3-epoxy-1- (1-ethoxyethoxy) propane (2,3-Epoxy-1- (1-ethoxyethoxy) propane) Phosphorus composite polarizer.

7. In the above 1, the coating thickness of the photocurable adhesive layer is 0.01 to 5㎛, composite polarizing plate.

8. In the above 1, the thickness of the composite retardation layer is 2 to 7㎛, the composite polarizing plate.

9. In the above 1, wherein the polarizer comprises a polarizing film, or a polarizing coating on the base film and the base film, the composite polarizing plate.

10. In the above 1, wherein the composite retardation layer is disposed on one surface of the polarizer, the other side of the protective film is a composite polarizing plate.

11. The image display device including the composite polarizing plate of any one of the above 1 to 10.

In the composite polarizing plate of the present invention, the bending property of the display and the adhesive property between the phase difference layers may be improved.

In addition, the composite polarizing plate of the present invention may exhibit good light leakage characteristics due to the improvement in the bending property due to the decrease in the expansion ratio due to the stiffness of the composite retardation layer.

In addition, the composite polarizing plate of the present invention can reduce the defective rate since the separation film peeling process is unnecessary during the manufacturing process.

In addition, the present invention can provide an image display device including the composite polarizing plate as described above.

1 is a graph showing stiffness slopes according to Examples and Comparative Examples of the present invention.

2 is a schematic cross-sectional view of a composite polarizing plate according to an embodiment of the present invention.

One embodiment of the present invention is a polarizer; And a composite retardation layer disposed on at least one surface of the polarizer and laminated from the polarizer in order of a first retardation layer, a photocurable adhesive layer, and a second retardation layer, wherein the composite retardation film is in a range of 20 to 90 ° C. The slope of the stiffness with respect to the temperature at -514 to -275 improves the bending characteristics of the display, the adhesion between the retardation layers, the stiffness of the composite retardation layer, and the warping characteristics. The present invention relates to a polarizing plate including a composite retardation layer.

Hereinafter, specific embodiments of the present invention will be described. However, this is only an example and the present invention is not limited thereto.

<Complex Polarizer>

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

Polarizer

The polarizer may use a polarizer commonly used in the art and is not particularly limited in kind. For example, the polarizer may be imparted with a polarizing function through a single polarizing film itself as a film form, or as a coating film. It may be imparted through a polarization coating formed on.

Specifically, the polarizer may be obtained by swelling, dyeing, crosslinking, stretching, washing and drying the polarizer forming film containing the polarizer-forming resin, the polarizer by coating a composition containing the polarizer-forming resin on the base film It may be obtained by forming a laminated film and stretching, dyeing, crosslinking, washing with water, drying or the like of the laminated film.

The polarizer-forming resin used in the above-mentioned polarizing film or polarizing coating is not particularly limited as long as it is a dichroic substance, that is, a resin which can be dyed by iodine. For example, polyvinyl alcohol-based resin, polyvinyl dehydrated Alcohol-based resins, dehydrochlorinated polyvinyl alcohol-based resins, polyethylene terephthalate-based resins, ethylene-vinyl acetate copolymer resins, ethylene-vinyl alcohol copolymer resins, cellulose-based resins, partially gumified resins thereof, and the like. . Among them, polyvinyl alcohol-based resins are preferred as the resin for polarizer formation from the viewpoint of excellent not only the effect of enhancing the uniformity of the degree of polarization in the plane but also the excellent dyeing affinity for iodine.

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

In addition, the composite polarizing plate according to an embodiment of the present invention may use an optical film capable of expressing polarization characteristics by coating a liquid crystal in addition to the polarizer described above.

complex Retardation layer

The composite retardation layer according to the present invention is disposed on at least one surface of the polarizer. The composite retardation layer and the polarizer may directly contact each other, and may further include a separate layer therebetween, and may further include a protective film therebetween.

In addition, the composite retardation layer according to the present invention is formed by laminating from the polarizer in the order of the first retardation layer, the photocurable adhesive layer and the second retardation layer.

The retardation film laminate according to the present invention has a slope with respect to the temperature of the stiffness in the range of 20 to 90 ° C -514 to -275.

As described above, the first retardation layer and the second retardation layer are used for the OLED display, and when used in the flexible display, excellent bending characteristics are required.

Conventional laminates of the first retardation layer and the second retardation layer have problems such as lack of bending characteristics, fold traces, interfacial peeling, poor appearance or deformation, and cracks.

Accordingly, the present invention introduces a composite retardation layer in which the first retardation layer and the second retardation layer are bonded with a photocurable adhesive, and a stiffness slope in a specific temperature range of the composite retardation layer is -514 to -275. To solve the above problems.

In addition, when the pressure-sensitive adhesive is used to bond the first retardation layer and the second retardation layer, a release film (carrier film) is used, and foreign material inflow defects due to static electricity generated during release film release during the manufacturing process are generated.

However, since the composite retardation layer according to the present invention uses a photocurable adhesive layer, the release film peeling process is unnecessary during the manufacturing process, thereby reducing the defective rate. In addition, even if the photocurable adhesive agent is formed to be thinner than the pressure-sensitive adhesive layer, it exhibits sufficient adhesive force, so that the composite polarizing plate can be thinned, whereby the bending property can be improved.

In addition, by adjusting the composition and content of the photocurable adhesive layer according to the present invention, it is possible to adjust the adhesion strength, heat resistance, durability, the size of the stiffness with respect to temperature.

If the slope of the stiffness is less than -514, the folding traces occur, the interface peeling, poor appearance or deformation occurs, and if the slope of the stiffness is more than -275 cracks.

The thickness of the composite retardation layer is not particularly limited, but may be, for example, 2 to 7 μm. In this case, the bending property and the adhesive property between the retardation layers may be improved, and 20 to 90 ° C. of the composite retardation layer according to the present invention. It may be desirable for the slope of the stiffness to be designed from -514 to -275 in the temperature range of.

The composite retardation layer according to the present invention may be bonded to the polarizer by means known in the art, for example, an adhesive, an adhesive may be used, preferably an adhesive may be used.

Retardation layer

The first retardation layer and the second retardation layer according to the present invention are bonded with the photocurable adhesive layer interposed therebetween.

As the first retardation layer and the second retardation layer, those known in the art may be used. For example, it may be a stretched or unstretched polymer film, a liquid crystal layer obtained by curing a reactive liquid crystal compound, and specifically, the first retardation layer may be a λ / 2 retardation layer, and the second retardation layer may be a λ / 4 retardation layer. Can be.

For example, when the first retardation layer and the second retardation layer are made of a liquid crystal layer, a reactive liquid crystal compound (RM) may be used as a liquid crystal compound having optical anisotropy and crosslinking by light or heat. Examples thereof include the information described in Information Display 10 Volume 1 (Recent Research Trends of 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, but specifically, pin coating, roll coating, dispensing coating, or gravure coating may be used. It is desirable to determine the type and amount of solvent depending on the coating method.

The base film is not limited to a specific kind, but one of the protective films described below may be selected.

Photocurable Adhesive layer

The photocurable adhesive layer which concerns on this invention is used in the part which requires the bonding between the 1st phase difference layer and the 2nd phase difference layer of a composite retardation layer.

If necessary, the photocurable adhesive layer according to the present invention may 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 may be formed of a photocurable adhesive composition capable of performing photocurable adhesion, and the photocurable adhesive composition may be used without particular limitation as long as it can perform photocurable adhesion. For example, the photocurable adhesive composition may include a photopolymerizable compound, a photoinitiator, and the like.

The photopolymerizable compound may be an optical radical polymerizable compound or a photo cationic polymerizable compound known in the art. These can be used individually or in mixture of 2 or more types.

Examples of the radical photopolymerizable compound employ the radical photopolymerizable compound exemplified in paragraph [0100] of Korean Patent Laid-Open Publication No. 2015-0017446.

In addition, a polymer polymerized with the monomers may be used as the radical photopolymerizable compound.

Examples of the photo cationic polymerizable compound employ the photo cationic polymerizable compound exemplified in the paragraph of Korean Patent Laid-Open Publication No. 2015-0017446.

Photocurable adhesive composition according to an embodiment of the present invention it may be preferable to include an alicyclic epoxy compound and a linear aliphatic epoxy compound in terms of adhesive properties and stiffness control.

By adjusting the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound, the adhesion to the first retardation layer and the second retardation layer and the adjustment of the stiffness may be easier. In this aspect, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is preferably in the range of 1: 1.5 to 1: 4, and more preferably in the range of 1: 2 to 1: 4. If the above range is satisfied, the bending property is improved due to the improvement of interlayer peeling and the decrease of the expansion rate due to the improved stiffness through the improved adhesive property between the retardation layers, thereby exhibiting good light leakage characteristics.

In this case, the alicyclic epoxy compound and the linear aliphatic epoxy compound are not particularly limited. For example, the alicyclic epoxy compound may be 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (3,4). -Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate)

Linear aliphatic epoxy compounds include neopentyl glycol diglycidyl ether, 1,2,7,8-diepoxyoctane (1,2,7,8-Diepoxyoctane), 1,4-butanediol diol 1,4-Butanediol diglycidyl ether, 2-Ethyl Hexyl Glycidyl Ether, 1,2-Epoxy-9-decene ), And 2,3-epoxy-1- (1-ethoxyethoxy) propane (2,3-Epoxy-1- (1-ethoxyethoxy) propane).

In addition, the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound may further include other photo radical polymerizable compounds and photo cationic polymerizable compounds as necessary, and the content thereof may be 1 to 20 based on the total weight of the photocurable adhesive composition. A weight percent range is preferred.

In addition, the content of the photocationic polymerization initiator, the content of the photopolymerization initiator and the coating method of the photocurable adhesive composition uses the contents of paragraphs [0102] to [0104] of Korea Patent Publication No. 2015-0017446.

The coating thickness of a photocurable adhesive composition is not specifically limited, For example, it can coat with 0.01-5 micrometers, Preferably it is 0.5-3 micrometers.

When the coating thickness of the photocurable adhesive composition exceeds 5 μm, application to a polarizing plate for general display is possible, but cracking of the protective substrate may occur when evaluating the bending property of the flexible display.

Protective film

The protective film may be bonded to at least one surface of the polarizer. For example, when the composite retardation layer is disposed on one surface of the polarizer, the protective film may be bonded to the other surface. In addition, the protective film may be disposed between the composite retardation layer and the polarizer, but is not limited thereto.

Examples of the protective film and its contents use the contents of paragraphs [0111] to [0114] of Korean Patent Application Publication No. 2015-0015569.

The thermosetting or ultraviolet curing resin may be a cured layer formed from an aryl resin, a urethane resin, an acryl-urethane resin, an epoxy resin, a silicone resin or the like, but is not limited to a specific film and may be used in consideration of adhesion or durability.

The thickness of the protective film is not particularly limited, but may be 10 to 200 μm, preferably 10 to 150 μm. When the thickness of the protective film is 10 to 200㎛, when the polarizer protective film is laminated on both sides of the polarizer, each protective film may have the same or different thickness from each other.

<Image display device>

In addition, the composite polarizing plate of the present invention can be usefully applied to an image display device or the like in combination with other conventional configurations.

As an image display device, not only an ordinary liquid crystal display device but also an electroluminescent display device, a plasma display device, a field emission display device, an OLED, etc. can be mentioned, In the case where the composite polarizing plate of this invention is applied to OLED, It is preferable to arrange | position to the viewing side.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but these examples are merely illustrative of the present invention and are not intended to limit the scope of the appended claims, which are within the scope and spirit of the present invention. It is apparent to those skilled in the art that various changes and modifications can be made to the present invention, and such modifications and changes belong to the appended claims.

Preparation Example 1

A 75 μm thick polyvinyl alcohol film (PS 7500, Kuraray) having an average degree of polymerization of 2,400 and a saponification degree of 99.9% or more was swelled by immersion in water (deionized water) at 30 ° C. for 2 minutes and then 3.5 mmol / L of iodine After dyeing by immersion for 4 minutes in an aqueous solution for dyeing at 30 ℃ containing 2% by weight of potassium iodide, 2% by weight of potassium iodide, 3.7% by weight of boric acid, 4.5 mol of lithium chloride per 1 mole of potassium iodide It was immersed in an aqueous solution for crosslinking at 占 폚 for 2 minutes to crosslink. The polarizer was manufactured so that the cumulative draw ratio up to each swelling / dyeing / crosslinking / washing step may be 5.5 times.

Preparation Example 2

Noren W151 (Sumitomo Chemical Co., Ltd.) Noren FLX80E4 (Sumitomo Chemical Co., Ltd.) is placed on both sides of the resin layer to produce a three-layer base film by co-extrusion using a multilayer extrusion molding machine, and then polyvinyl alcohol powder. Z-200 (Japan Synthetic Co., Ltd.) was heated to 90 ° C. to prepare an aqueous solution of 3% by weight, and then a crosslinking agent, Sumirejin 650 (Daoka Chemical Co., Ltd.), was mixed at a ratio of 1% by weight to 2% by weight of polyvinyl alcohol powder. To obtain a coating solution for forming a primer layer, and heated polyvinyl alcohol powder PVA124 (Kuraray Co., Ltd.) at 90 ° C. to prepare an aqueous solution of 8% by weight to prepare a coating solution for forming a polyvinyl alcohol-based resin, followed by corona treatment on the multilayer base film. After coating, the primer layer was coated on the corona treated surface using a microgravure coater and dried at 80 ° C. for 3 minutes to form a primer layer having a thickness of 0.2 μm. Coating a carbonyl alcohol-based coating solution, which was continuously form a series of 10㎛ thick polyvinyl alcohol resin layer and dried at 90 ℃ 5 minutes.

The obtained multilayer film was stretched 5.8 times with a thermal roll at 160 ° C., immersed in pure water at 60 ° C. for 1 minute, immersed for 3 minutes in a dye solution of iodine and potassium iodide, and then stained with 75 containing boric acid and potassium iodide. It was immersed in a crosslinking solution of 10 minutes for 10 minutes, washed with 10 ℃ pure water, and then dried at 80 ℃ 5 minutes to prepare a polyvinyl alcohol polarizer having a thickness of 3.8㎛.

Example  One

(A) Preparation of Photocurable Adhesive Composition

The adhesive composition was formulated by combining 20 wt% of Daicel's alicyclic epoxy compound CEL 2021P, 80 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether, and 4 wt% of cationic photoinitiator CPI-110A of acid eprosa. In this case, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 4.

(B) Preparation of Composite Retardation Layer

The photocurable adhesive composition thus prepared was bonded to have a thickness of 3 µm between the λ / 2 retardation layer and the λ / 4 retardation layer, and then UV cured in a high-pressure mercury lamp (UVA accumulated light amount of 500 mJ / cm ² ) to form a composite retardation layer. .

(C) Preparation of Polarizing Plate

One surface of the polarizer of Preparation Example 1 was applied to a triacetyl cellulose-based film (FUJI Co., Ltd.) by applying and drying a water-based adhesive, and bonded to the other surface by using a film-type acrylic pressure-sensitive adhesive on the λ / 2 phase difference layer side of the composite retardation layer. Splicing. The film type acrylic adhesive was further bonded to the (lambda) / 4 phase (s) difference layer side of the said bonding structure, and the polarizing plate was produced.

2 is a schematic cross-sectional view of the composite polarizing plate.

Example  2

 A polarizing plate was prepared in the same manner as in Example 1 except that 30 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 70 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 2.3.

Example  3

20% by weight of Daicel's alicyclic epoxy compound CEL 2021P, 70% by weight of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether and 10% by weight of 1,2,7,8-diepoxyoctane The same polarizing plate as that in Example 1 was prepared except that the composition was prepared, and the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 4.

Example  4

The same polarizing plate as in Example 1, except that 20 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 80 wt% of Aldrich's linear aliphatic epoxy compound 1,2,7,8-diepoxyoctane were prepared. In this case, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 4.

Example  5

Same as Example 1 except that 20% by weight of Daicel's alicyclic epoxy compound CEL 2021P and 80% by weight of Aldrich's linear aliphatic epoxy compound 1,4-butanediol diglycidyl ether were prepared. A polarizing plate was prepared, and the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 4.

Example  6

The same polarizing plate as in Example 1 was prepared except that 20 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 80 wt% of Aldrich's linear aliphatic epoxy compound 2-ethylhexyl glycidyl ether were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 4.

Example  7

The same polarizing plate as in Example 1 was prepared except that 20 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 80 wt% of Aldrich's linear aliphatic epoxy compound 1,2-epoxy-9-decene were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 4.

Example  8

Except for preparing an adhesive composition by mixing 20 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 80 wt% of Aldrich's linear aliphatic epoxy compound 2,3-epoxy-1- (1-ethoxyethoxy) propane The same polarizing plate as in Example 1 was prepared, wherein the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 4.

Example  9

20 wt% of Daicel's alicyclic epoxy compound CEL 2021P, 70 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglycidyl ether, and 10 wt% of aromatic Aldrich's aromatic epoxy lesosinol diglycidyl ether The same polarizing plate as in Example 1 was prepared except that the adhesive composition was prepared, and the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 3.5.

Example  10

20% by weight of Daicel's alicyclic epoxy compound CEL 2021P, 70% by weight of linear aliphatic epoxy compound neopentyl glycol diglycidyl ether from Aldrich, 10% by weight of acrylate monomer glycidyl methacrylate from Aldrich, Ciba A polarizing plate was prepared in the same manner as in Example 1 except that 4 wt% of the radical photoinitiator Irg184 was added to prepare an adhesive composition. The weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 3.5.

Example  11

20% by weight of Daicel's cycloaliphatic epoxy compound CEL 2021P, 70% by weight of linear aliphatic epoxy compound neopentyl glycol diglycidyl ether from Aldrich, 10% by weight of aromatic epoxy of aromatic Aldrich's and acrylate monomer glycidyl methacryl A polarizing plate was prepared in the same manner as in Example 1 except that an adhesive composition was prepared by mixing 10 wt% of a ratio and 4 wt% of a radical photoinitiator Irg184 of Ciba, and the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 3.

Example  12

A polarizing plate was manufactured in the same manner as in Example 1 except that the thickness of the adhesive was 5 μm.

Example  13

A polarizing plate was manufactured in the same manner as in Example 1 except that the thickness of the adhesive was 1 μm.

Example  14

A polarizing plate was used in the same manner as in Example 1, except that the polarizer of Preparation Example 2 was used as the polarizer, and the triacetyl cellulose-based film (FUJI) was bonded to the side where the polyvinyl alcohol-based resin layer was formed on both sides of the polarizer. Was prepared.

Comparative example  One

The same polarizing plate as in Example 1 was prepared except that 10 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 90 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 9.

Comparative example  2

 A polarizing plate was prepared in the same manner as in Example 1 except that 70 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 30 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 0.4.

Comparative example  3

70% by weight of Daicel's alicyclic epoxy compound CEL 2021P, 20% by weight of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether, and 10% by weight of 1,2,7,8-diepoxyoctane The same polarizing plate as that in Example 1 was prepared except that the composition was prepared, and the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound was 1: 0.4.

Comparative example  4

60 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 40 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether were prepared to prepare the same polarizing plate as in Example 1. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 0.7.

Comparative example  5

A polarizing plate was prepared in the same manner as in Example 1, except that 50 wt% of Daicel's alicyclic epoxy compound CEL 2021P and 50 wt% of Aldrich's linear aliphatic epoxy compound neopentyl glycol diglyceryl ether were prepared. At this time, the weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound is 1: 1.

Comparative example  6

The acrylic copolymer was polymerized with 70% by weight of butyl acrylate, 20% by weight of methyl acrylate, and 10% by weight of acrylic acid, and 15% by weight of the polyfunctional acrylate monomer and 0.3% by weight of the photopolymerization initiator (Irgacure500, Chiba Chemical Co., Ltd., an isocyanate crosslinking agent (Colonate L, Nippon Polyurethane Industry Co., Ltd.), and 0.1 wt% of a silane coupling agent (KBM-403, Shinnets Chemical Co., Ltd.) were added to prepare an acrylic pressure-sensitive adhesive composition. The prepared pressure-sensitive adhesive composition was applied to a separator film having a thickness of 80 μm and dried to prepare an adhesive film having an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm.

The same polarizing plate as in Example 1 was prepared except that the PSA layer was repeatedly transcribed onto a λ / 2 retardation layer of the composite retardation layer to form an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm, and the λ / 4 retardation layer was bonded thereon.

Comparative example  7

A polarizing plate similar to Comparative Example 6 was prepared except that the thickness of the acrylic pressure sensitive adhesive layer was 5 μm.

Comparative example  8

A polarizing plate was manufactured in the same manner as in Example 1 except that the thickness of the adhesive was 7 μm.

Stiffness  Tilt measurement

After cutting the composite retardation layer prepared in Examples and Comparative Examples to a size of 2mm X 50mm, and from 30 ℃ to 80 ℃ in the longitudinal direction with a dynamic thermal analyzer (Q-800, TA Instrument) for the gage distance 15mm The stiffness was evaluated by heating up. At this time, the stiffness at 30 degreeC, 50 degreeC, and 80 degreeC was taken and the slope of stiffness was calculated | required. The slope of the stiffness was obtained from a graph showing the temperature (° C.) and the stiffness magnitude with respect to the temperature, and the slope of the stiffness was obtained by linear regression analysis. The stiffness slopes of Examples 1, 12, 13 and Comparative Example 7 are shown in the temperature-stiffness graph of FIG.

Hereinafter, the composition contents of Examples 1 to 14 are expressed in weight percent.

Hereinafter, the composition content of Comparative Examples 1 to 8 is expressed in weight%.

A-1: CEL 2021P (DIESEL Co., Ltd.)

B-1: neopentyl glycol diglyceryl ether

B-2: 1,2,7,8-diepoxyoctane

B-3: 1,4-butanediol diglycidyl ether

B-4: 2-ethylhexyl glycidyl ether

B-5: 1,2-epoxy-9-decene

B-6: 2,3-epoxy-1- (1-ethoxyethoxy) propane

B'-1: acrylic adhesive

C-1: Lesosinol diglycidyl ether

D-1: glycidyl methacrylate

Evaluation test

(1) Cross Cut

The interlayer adhesion of the composite retardation layer (whether interlayer peeling) was tested according to the standard of ASTM D 3359 for the composite polarizing plates of the examples and comparative examples. 11 cutting lines are inserted in the longitudinal and transverse directions at intervals of 1 mm on the surface of the composite retardation layer to form 100 eyes of 1 mm ² , and then the cellophane tape is applied to the surface, and then the process of peeling is repeated three times. It carried out and counted the average peeling number, and evaluated according to the following criteria.

OK: 0-10 peels

NG: 10 or more peeling numbers

(2) Light fountain  evaluation

The prepared polarizing plate was attached to the glass using a film-type adhesive, and then a silver reflecting plate was attached to the opposite side of the polarizing plate attaching surface, and the light polarizing plate was put into an oven at 85 ° C. for 24 hours, and the light leakage of the polarizing plate was observed in the reflection mode in the dark room.

○: no light leakage

X: light leakage phenomenon

(3) bending evaluation

Using a bending test apparatus (MIT evaluation), repeated bending experiments were performed with a width of 10 mm, a length of 150 mm, and a radius of 3 mm to observe cracking degree and peeling between layers of films during 50,000 repeated bending tests.

[Crack]

○: no protective substrate crack

△: within 2 mm of the end portion of the protective base material crack

X: Front crack of protective substrate

[Interlayer Peeling]

○: no interlayer peeling

(Triangle | delta): Within 2 mm of edge part peeling distances of a protective base material / adhesive protective base material

X: End peeling distance of 2 mm or more of protective base material / adhesive protective base material

Referring to Tables 3 and 4, the examples are excellent in both Cross Cut, light leakage evaluation and bending evaluation, the comparative examples are not excellent in both Cross Cut, light leakage evaluation and bending evaluation.

Claims (11)

Polarizer; And And a composite retardation layer disposed on at least one surface of the polarizer and stacked from the polarizer in order of a first retardation layer, a photocurable adhesive layer, and a second retardation layer. The composite retardation layer is a composite polarizing plate having a slope with respect to the temperature of the stiffness in the range of 20 to 90 ℃ -514 to -275. The composite polarizing plate according to 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 includes an alicyclic epoxy compound and a linear aliphatic epoxy compound. The composite polarizing plate according to claim 3, wherein the photocurable adhesive has a weight ratio of the alicyclic epoxy compound and the linear aliphatic epoxy compound of 1: 1.5 to 4. The composite polarizing plate according to claim 3, wherein the alicyclic epoxy compound is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (3,4-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate). The method of claim 3, wherein the linear aliphatic epoxy compound is neopentyl glycol diglycidyl ether (neopentyl glycol diglycidyl ether), 1,2,7,8-diepoxyoctane (1,2,7,8-Diepoxyoctane), 1,4-Butanediol diglycidyl ether, 2-Ethyl Hexyl Glycidyl Ether, 1,2-Epoxy-9-decene (1,2 -Epoxy-9-decene) and at least one selected from the group consisting of 2,3-epoxy-1- (1-ethoxyethoxy) propane (2,3-Epoxy-1- (1-ethoxyethoxy) propane), Composite polarizer. The composite polarizing plate of Claim 1 whose coating thickness of the said photocurable adhesive bond layer is 0.01-5 micrometers. The composite polarizing plate according to claim 1, wherein the composite retardation layer has a thickness of 2 to 7 μm. The composite polarizer of claim 1, wherein the polarizer comprises a polarizing film or a polarizing coating on a base film and a base film. The composite polarizing plate of claim 1, wherein the composite retardation layer is disposed on one surface of the polarizer, and a protective film is bonded to the other surface. The image display apparatus containing the composite polarizing plate of any one of Claims 1-10.

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