TWI715683B - 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℃, 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 composite polarizing plate

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

Consistent with information display terminal devices such as mobile phones and PDAs, the development trend of information display is moving from being able to actually present objects with high performance and high functions as the center toward mobility and convenience. Therefore, there is a great demand for flexible displays that are light in weight and easy to fold without space and shape restrictions.

More specifically, a flexible display refers to a display manufactured using a flexible substrate that can be bent or folded, and depending on its use and function, it can be classified into a rough display, a flexible display, and a rollable display. In addition, the flexible display is a display under development, so by replacing the existing flat panel display (FDP) with a thin and flexible substrate, such as thin film for liquid crystal display (LCD) or organic light emitting diode (OLED) Transistor (TFT) device substrates, color filter substrates, substrates for touch screen panels, and substrates for solar cells use heavy and fragile glass plates, which are used in a variety of applications due to space and shape constraints Applicability. In the end, about Continuous research and development of flexible displays are actively moving towards the commercialization of paper-like displays that can be twisted and deformed.

The flexible substrate used in such a flexible display is formed into 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. If the adhesion between the retardation layers is weak, there will be problems such as swelling of the adhesive layer or peeling of the retardation layer.

For example, Korean Patent Registration No. 1191865 discloses related technologies for flexible substrates, but does not propose a solution to the aforementioned problems.

Therefore, one objective of the present invention is to provide a composite polarizer that has improved bending properties of displays and adhesion properties between retardation layers.

In addition, another object of the present invention is to provide a composite polarizing plate with excellent light leakage properties due to the improved rigidity and bending properties of the composite retardation layer.

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

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

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

(2) The composite polarizer according to the above (1), 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 includes a cycloaliphatic epoxy compound and a linear aliphatic epoxy compound.

(4) The composite polarizing plate according to the above (3), wherein the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound contained 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-epoxycyclohexane carboxylate.

(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-Diepoxy octane, 1,4-Butanediol diglycidyl ether, 2-Ethylhexyl glycidyl ether, 1,2-Epoxy-9-decene 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 0.01 μm to 5 μm.

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

(9) The composite polarizing plate according to (1) above, wherein the polarizer includes 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 retardation layer is disposed on a surface of the polarizer, and the protective film is adhered to the polarizer The other surface of the light mirror.

(11) An image display device including 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 properties of the display and the adhesion properties between the retardation layers.

In addition, according to the composite polarizer of the present invention, by reducing the expansion rate caused by the rigidity improvement of the composite retardation layer, it may have the excellent light leakage properties exhibited by the improvement of the bending properties.

Furthermore, according to the composite polarizing plate of the present invention, since the manufacturing process does not require the process of separating the film, it is possible to reduce the defect rate of the product.

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

The above and other objectives, features and other advantages of the present invention will be more clearly understood from the detailed description part of the following in conjunction with the accompanying drawings. In the accompanying drawings:

Fig. 1 is a diagram illustrating the gradient of rigidity according to the embodiment of the present invention and the comparative example.

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

The present invention discloses a composite polarizing plate comprising: a polarizer; and a composite retardation layer, which is arranged on at least one surface of the polarizer, so that the first retardation layer, the photocurable adhesive layer and the second retardation layer It is from the polarizer stack in this order, in which the composite retardation layer has a gradient of -514 to -275 with respect to the rigid temperature within the range of 20°C to 90°C, and an image display device including the aforementioned composite polarizer. Therefore, the composite polarizer has the improved bending properties of the display and the adhesion properties between the retardation layers, and exhibits excellent light leakage properties due to the improved rigidity and bending properties of the composite retardation layer.

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

<Composite Polarizing Plate>

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

Polarizer

The polarizer can be a polarizer that is typically used in related technical fields, and there is no particular limitation on its type. For example, the polarization performance can be applied to the polarizer in the form of a thin film through a single polarizing film itself, and can be applied in the form of coating through a polarizing coating film formed on the base film.

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

The type of resin used to form the polarizer used in the aforementioned polarizing film or polarizing coating film is not particularly limited, as long as it can be dichroic Sexual materials such as iodine dyeing may be sufficient, and may include, for example, polyvinyl alcohol resin, dehydrated polyvinyl alcohol resin, dehydrochlorinated polyvinyl alcohol resin, polyethylene terephthalate resin, ethylene-vinyl acetate Copolymer resin, ethylene-vinyl alcohol copolymer resin, cellulose resin, and/or partially saponified resin thereof, or the like. Among these resins, it is preferable to use polyvinyl alcohol resin as the resin used to form the polarizer in terms of enhanced uniformity of polarization in the plane and excellent dyeing affinity for dichroic materials such as iodine.

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

In addition, in addition to the aforementioned polarizer, the composite polarizing plate according to the specific example of the present invention can also use an optical film capable of expressing polarization characteristics by coating liquid crystal thereon.

Composite retardation layer

The composite retardation layer according to the present invention is arranged on at least one surface of the polarizer. The composite retardation layer and the polarizer can be directly bonded to each other, can further include a separate layer between them, and can further include protection between them.

In addition, according to the method of forming the composite retardation layer of the present invention, the first retardation layer, the photocurable adhesive layer and the second retardation layer are arranged in this order from the polarizer stack.

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

As described above, the first retardation layer and the second retardation layer are used in OLED displays, and when these layers are used in flexible displays, excellent bending properties are required.

The conventional laminates of the first retardation layer and the second retardation layer have problems such as creases due to insufficient bending properties, interlayer peeling, defect appearance or deformation, and cracks.

In this aspect, the present invention introduces a composite retardation layer in which the first retardation layer and the second retardation layer are bonded to each other by a photo-curable adhesive, and provided within a specific temperature range of the composite retardation layer. The composite retardation layer of rigid gradient of 514 to -275, thus solving the aforementioned problem.

In addition, when a pressure-sensitive adhesive is used to adhere the first retardation layer and the second retardation layer to each other, a release film (carrier film) is used. In this case, due to the static electricity generated during the tearing off of the release film during the manufacturing process, foreign matter may be introduced and it may be rejected.

However, the composite retardation layer according to the present invention uses a light-curable adhesive layer, which makes it possible to reduce the defect rate of the product, because the process of tearing off the release film is not required. Furthermore, since the photo-curable 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 properties are improved.

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

If the rigidity gradient is less than -514, creases will appear, as well as delamination, defective appearance or deformation. If the rigidity gradient exceeds -275, cracks appear.

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 properties and adhesion properties between the retardation layers can be improved. Preferably, the composite retardation layer according to the present invention is designed to have a rigidity gradient of -514 to -275 within the 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 the polarizer by using any related known means, and for example, a pressure-sensitive adhesive or an adhesive can be used, and an adhesive is preferably used.

Retardation layer

According to the first retardation layer and the second retardation layer of the present invention, a photo-curable adhesive layer is interposed therebetween to be bonded.

The first retardation layer and the second retardation layer may respectively use retardation 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 retardation layer may be a λ/2 retardation layer, and the second retardation layer may be a λ/4 retardation layer.

For example, when the first retardation layer and the second retardation layer are made 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 resources Information Display (Information Display) 10 [1] (Recent Research Trend in Reactive Liquid Crystal Monomer (RM)).

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

The type of the base film is not particularly limited, and can include any of the protective films described later.

Light-curable adhesive layer

The light-curable adhesive layer according to the present invention is used for bonding the required parts of the first retardation layer and the second retardation layer of the composite retardation layer.

If necessary, 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 photo-curable adhesive layer according to the present invention may be made of a photo-curable adhesive composition capable of photo-curable bonding. In this context, the photo-curable adhesive composition can be used without particular limitation, as long as it can perform photo-curable bonding. 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 can be used alone or in combination of two or more of them.

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

In addition, polymers polymerized with the aforementioned monomers can be used as photo radical polymerizable compounds.

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

Preferably, according to a specific example of the present invention, in terms of controlling the adhesive properties and rigidity, the photocurable adhesive composition includes cycloaliphatic epoxy compounds and linear aliphatic epoxy compounds.

By controlling the weight ratio of the content of the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound, it may be easier to improve the adhesion between the first retardation layer and the second retardation layer and control the rigidity. In this aspect, it is preferable 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, a weight ratio of 1:2 to 1:4 range. Within the aforementioned range, through the improved adhesion properties between the retardation layers, the tearing from the interlayer and the improvement of rigidity lead to the improvement of bending properties, which 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-Epoxycyclohexane carboxylate.

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

In addition, if necessary, the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound may further include the photoradical polymerizable compound and the photocationic polymerizable compound as described above. Preferably, the content of these polymerizable compounds is in the range of 1% to 20% wt.%.

In addition, as for the examples of the description of the photocationic polymerizable compound, the content of the photopolymerization initiator, and the coating method of the photocurable adhesive composition, the Korean Patent Early Publication No. 2015-0017446 is used. Description of paragraphs [0102] to [0104].

The coating thickness of the photo-curable adhesive composition is not particularly limited, and for example, the photo-curable adhesive composition is coated with a thickness of 0.01 μm to 5 μm, and preferably, 0.5 μm to 3 μm.

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

Protective film

The protective film may be adhered 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 can be adhered to the other surface of the polarizer. In addition, the protective film can be disposed between the composite retardation layer and the polarizer, but it is not limited by this.

The descriptions in paragraphs [0111] to [0114] in Korean Patent Early Publication No. 2015-0017446 can be used as examples and descriptions of the protective film.

In addition, as for thermosetting resins or UV curable resins, aryl resins, urethane resins, acryl-urethane resins, epoxy resins, silicone resins, etc. may be used to form a cured layer. However, it is not limited to a specific film, and in consideration of adhesion or durability, any of the above resins can be suitably 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 the two surfaces of the polarizer, the individual protective films may have the same or different thicknesses.

<Image display device>

Furthermore, the composite polarizer of the present invention can be effectively applied to image display devices by combining with other conventional components.

The image display device can use, for example, a typical liquid crystal display device, and in addition, an electroluminescent display device, a plasma display device, an electroluminescent display device, an OLED, etc. can be used. When the composite polarizer of the present invention is applied to the OLED, preferably, the side of the polarizer is arranged on the side that can be seen.

In the following, preferred embodiments are presented to more specifically describe the present invention. However, the following embodiments are only used to illustrate the present invention, and those skilled in the relevant technical field will obviously understand that various changes and modifications are possible within the scope and spirit of the present invention. These changes and modifications are properly included in the attached patent application range.

Preparation Example 1

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

Preparation Example 2

Noblen FLX80E4 resin (Sumitomo Chemical Co., Ltd.) is placed on both sides of the resin layer (Sumitomo Chemical Co.) of Noblen W151, and the preparation method of the base film with a three-layer structure A multilayer extrusion molding machine was used for co-extrusion molding, 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, Sumirejin 650 (Taoka Chemical Co., Ltd.) as a cross-linking agent was mixed in a ratio of 1 wt.% to 2 wt.% polyvinyl alcohol powder to obtain a coating for forming a primer layer. The coating solution, and PVA 124 polyvinyl alcohol powder (Curaray Company) were heated at 90° C. to obtain an 8 wt.% aqueous solution, thus preparing a coating solution for forming a polyvinyl alcohol resin. Secondly, more The base film of the layer is corona treated, and the bottom layer is coated on the corona treated surface using a microgravure printing coater, and dried at 80°C for 3 minutes to form a 0.2μm bottom layer, and then the polyvinyl alcohol coating solution is continuous Ground is coated on the bottom layer and dried at 90°C for 5 minutes to form a polyvinyl alcohol resin layer with a thickness of 10 μm.

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

Example 1

(A) Preparation of light-curable adhesive composition

By mixing 20wt.% of CEL 2021P (Daicel Co.) as a cycloaliphatic epoxy compound and 80wt.% of neopentyl glycol diglycidyl ether (a Aldrich Co., 4wt.% 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 light-curable adhesive composition adheres between the λ/2 retardation layer and the λ/4 retardation layer, thus forming a thickness of 3μm between them, and using a high-pressure mercury lamp (UVA, at 500mJ/cm ² The integrated light quantity) is UV cured thereon, thus preparing a composite retardation layer.

(B) Preparation of polarizing plate

The triacetyl cellulose film (Fuji Co.) was adhered to one surface of the polarizer prepared in Preparation Example 1 and the λ/2 of the composite retardation layer by applying an aqueous adhesive and drying it The side of the retardation layer is adhered to the other surface using an acrylic pressure-sensitive adhesive. The film-type acrylic pressure-sensitive adhesive is further bonded to the λ/4 retardation layer configured as above, thereby preparing a polarizing plate.

In Figure 2, a cross-sectional view of the composite polarizer is schematically illustrated.

Example 2

The polarizing plate was manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 30wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 70wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 20wt.% of CEL 2021P as a cycloaliphatic epoxy compound (Diesel), and 70wt.% of neopentyl glycol diglycidyl ether and 10%wt.% of 1,2,7,8-diepoxy octane as linear aliphatic epoxy compound (Yalixu Company). In this case, cycloaliphatic epoxy compounds and linear aliphatic epoxy compounds The weight ratio is 1:4.

Example 4

The polarizing plate was manufactured according to the same procedure as described in Example 1, but the preparation method of the adhesive composition was as follows: By mixing 20wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 80% wt.% 1,2,7,8-diepoxy octane as linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the preparation method of the adhesive composition was as follows: By mixing 20wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 80% wt.% of 1,4-butanediol diglycidyl ether as linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the preparation method of the adhesive composition was as follows: By mixing 20wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 80% wt.% of 2-ethylhexyl glycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:4.

Example 7

The polarizer is based on the same procedure as described in Example 1. Manufacture, but the preparation method of the adhesive composition is as follows: by mixing 20wt.% of CEL 2021P (Diesel) as a cycloaliphatic epoxy compound and 80%wt.% of a linear aliphatic epoxy compound 1,2-Epoxy-9-decene (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the preparation method of the adhesive composition was as follows: By mixing 20wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 80% wt.% 2,3-epoxy-1-(1-ethoxyethoxy)propane as a linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 20wt.% as a cycloaliphatic epoxy compound CEL 2021P (Dai Suo company), 70wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company), and 10wt.% of dihydroxybenzene diglycidyl ether (Yalixu) as an aromatic epoxy compound 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 20wt.% as a cycloaliphatic epoxy compound CEL 2021P (Dai Suo company), 70wt. % Neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company), 10wt.% of glycidyl methacrylate as an aromatic acrylate monomer (Yalixu Company), And 4wt.% of Irg 184 (Siba Co.) as a free 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 20wt.% as a cycloaliphatic epoxy compound CEL 2021P (Dai Suo company), 70wt. % As linear aliphatic epoxy compound neopentyl glycol diglycidyl ether (Yalixu company), 10wt.% as aromatic epoxy compound between dihydroxybenzene diglycidyl ether (Yalixu company ), 10wt.% of glycidyl methacrylate as aromatic acrylate monomer (Yalixu Company), and 4wt.% of Yige 184 (Sieba Company) as a free 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 manufactured according to the same procedure as described in Example 1, but the adhesive had a thickness of 5 μm.

Example 13

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

Example 14

The polarizer was manufactured according to the same procedure as described in Example 1, but the polarizer prepared in Preparation Example 2 was used as the polarizer, and the triacetyl cellulose film (Fuji Company) was bonded to one of the two surfaces of the polarizer On the side, polyvinyl alcohol resin is formed thereon.

Comparative example 1

The polarizing plate was manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 10wt.% of CEL 2021P (Diesel Company) as a cycloaliphatic epoxy compound and 90wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 70wt.% of CEL 2021P (Diesel) as a cycloaliphatic epoxy compound and 30wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the preparation method of the adhesive composition was as follows: by mixing 70wt.% of CEL 2021P as a cycloaliphatic epoxy compound (Diesel), and 20wt.% of neopentyl glycol diglycidyl ether and 10%wt.% of 1,2,7,8-diepoxyoctane as a linear aliphatic epoxy compound (Yalixu Company). in 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 60wt.% of CEL 2021P as a cycloaliphatic epoxy compound (Diesel) and 40wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). 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 manufactured according to the same procedure as described in Example 1, but the adhesive composition was prepared as follows: by mixing 50wt.% of CEL 2021P as a cycloaliphatic epoxy compound (Diesel) and 50wt. % Of neopentyl glycol diglycidyl ether as a linear aliphatic epoxy compound (Yalixu Company). In this case, the weight ratio of the cycloaliphatic epoxy compound to the linear aliphatic epoxy compound is 1:1.

Comparative example 6

With 70wt.% butyl acrylate, 20wt.% methyl acrylate, and 10wt.% acrylic polymerized acrylic copolymer, and 15wt.% multifunctional acrylate monomer, 0.3wt.% as photopolymerization The starting agent is Irgacure 500 (Ciba Chemical Co.), Colonate L (Nippon Polyurethane Industry Co.) as the isocyanate Crosslinking agent, and 0.1wt.% of KBM-403 as a silane coupling agent (Xinyue Chemical Company (Shinetsu Chemical Co.)) was added to the above-mentioned acrylic copolymer to prepare an acrylic pressure-sensitive adhesive composition. 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 manufactured according to the same procedure as described in Example 1, but 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 with a thickness of 20 μm Layer, and the λ/4 retardation layer is bonded to it.

Comparative example 7

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

Comparative example 7

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

Stiffness gradient measurement

The composite retardation layer prepared in the Examples and Comparative Examples was cut into a size of 2mmx50mm, and then heated from 30°C to 80°C using a dynamic thermal characteristics analyzer (Q-800, TA Instruments) in the longitudinal direction The 15mm meter distance evaluates the rigidity. At this time, select the rigidity at 30°C, 50°C, and 80°C to measure the rigidity gradient. The rigidity gradient is obtained from the graph, where the X axis represents the temperature (°C) and the Y axis represents the rigidity amplitude for each temperature, and the rigidity gradient is calculated based on linear regression analysis. The rigidity gradients of Examples 1, 12, and 13 and Comparative Example 7 are shown in the temperature-rigidity diagram in Figure 1.

Evaluation test

(1) Evaluation of cross cutting

The composite polarizing plates prepared in the Examples and Comparative Examples are tested for interlayer adhesion (whether there is interlayer tearing) according to the ASTM D 3359 standard. Firstly, 11 cutting lines were carved longitudinally and laterally on the surface of the composite polarizer at intervals of 1 mm to form 100 levels with an area of 1 mm ² . Then, the process of attaching the cellophane tape to the surface and removing the tape from the surface was repeated three times, counting the average number of tear-offs, and evaluating the cross cut 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 tearing off

NG: Tear-off occurred 10 times or more

(2) Evaluation of light leakage

The prepared polarizing plate was bonded to the glass using a film-type pressure-sensitive adhesive, and the silver reflective 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 the reflection mode in a dark room, and evaluated according to the following standards. The evaluation results are shown in Table 3 and Table 4 below.

○: No light leakage

X: Light leaks

(3) Evaluation of bending

Use a bending tester (MIT evaluation) to have a width of 10mm The specimens with a length of 150mm and a radius of 3mm are subjected to repeated bending tests. During up to 50,000 repeated bending tests, observe and evaluate the degree of cracks and the degree of interlayer tearing of the film according to the following standards. The evaluation results are shown in Table 3 and Table 4 below.

[crack]

○: No cracks appear

△: Cracks smaller than 2mm appear at the end of the protective substrate

X: Cracks appear on all surfaces of the protective substrate

[Tear off between layers]

○: No interlayer tearing occurs

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

X: A tear with a tear length exceeding 2mm at the end of the protective substrate/adhesive protective substrate

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 part of the composite retardation layer of the comparative example is in cross-cutting, light leakage and bending. There is no excellent evaluation result in the evaluation.

Claims (11)

A composite polarizing plate includes: a polarizer; and a composite retardation layer, which is arranged on at least one surface of the polarizer, so that the first retardation layer, the photocurable adhesive layer, and the second retardation layer are based on this This sort of sequence is from the polarizer stack, wherein the composite retardation layer has a gradient of -514 to -275 with respect to the temperature of the rigidity within the range of 20°C to 90°C. According to the composite polarizing plate described in claim 1, wherein the first retardation layer is a λ/2 retardation layer, and the second retardation layer is a λ/4 retardation layer. According to the composite polarizing plate described in item 1 of the scope of the patent application, the photo-curable adhesive of the photo-curable adhesive layer includes cycloaliphatic epoxy compounds and linear aliphatic epoxy compounds. The composite polarizing plate described in item 3 of the scope of patent application, wherein the weight ratio of the cycloaliphatic epoxy compound and the linear aliphatic epoxy compound contained in the photocurable adhesive is 1:1.5 To 4. The composite polarizing plate described in item 3 of the scope of patent application, wherein the cycloaliphatic epoxy compound is 3,4-epoxycyclohexylmethyl or 3,4-epoxycyclohexane carboxylate. The composite polarizing plate described in item 3 of the scope of patent application, wherein the linear aliphatic epoxy compound is at least one selected from the group consisting of: neopentyl glycol diglycidyl Ether, 1,2,7,8-diepoxy octane, 1,4-butanediol diglycidyl ether, 2-ethylhexyl condensation Hydroglyceryl ether, 1,2-epoxy-9-decene and 2,3-epoxy-1-(1-ethoxyethoxy)propane. The composite polarizing plate according to the first item of the scope of patent application, wherein the photocurable adhesive layer has a coating thickness of 0.01 μm to 5 μm. The composite polarizing plate described in the first item of the scope of patent application, wherein the composite retardation layer has a thickness of 2 μm to 7 μm. The composite polarizing plate according to the first item of the patent application, wherein the polarizer includes a polarizing film, or a base film, and a polarizing coating film on the base film. The composite polarizing plate described in claim 1, wherein the composite retardation 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 as described in any one of items 1 to 10 in the scope of patent application.

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