KR102196372B1 - Polarization plate set and liquid crystal display panel integrated with front plate - Google Patents

Abstract

The front plate 10 disposed on the visible side of the liquid crystal cell and having a Young's modulus of 2 Gpa or more, which is a side far from the liquid crystal cell, is bonded to the front polarizing plate 30 through an ultraviolet curable resin or adhesive 20 As a set of an integrated polarizing plate 40 and a rear polarizing plate 50 disposed on the rear side of the liquid crystal cell, the front polarizing plate 30 is at 85° C. in a state in which the front plate 10 is not bonded. The dimensional change rate in the absorption axis direction when heated for 100 hours is greater than the dimensional change rate in the absorption axis direction when the rear polarizing plate 50 is heated at 85° C. for 100 hours. This set of polarizing plates is bonded to a liquid crystal cell to obtain a front plate-integrated liquid crystal display panel.

Description

Polarization plate set and front plate integrated liquid crystal display panel {POLARIZATION PLATE SET AND LIQUID CRYSTAL DISPLAY PANEL INTEGRATED WITH FRONT PLATE}

The present invention relates to a set of polarizing plates comprising a rear polarizing plate having different dimensional shrinkage rates in a high temperature environment and a front polarizing plate in which a front plate is integrated, and a front plate-integrated liquid crystal display panel in which these are bonded to a liquid crystal cell.

BACKGROUND OF THE INVENTION Liquid crystal display devices have conventionally been used for desktop computers, electronic watches, personal computers, and the like, but their demand is rapidly increasing in recent years, and in recent years, their uses are also expanding, such as being used for mobile phones and tablet terminals. In such a liquid crystal display device, a pair of polarizing plates are usually arranged on the front and back of a liquid crystal cell to become a liquid crystal display panel.

In the recent market, with the spread of mobile devices such as mobile phones and tablet-type terminals with large screens, there is a demand for lighter and thinner liquid crystal display panels, which are constituent members, so that the glass or front plate of the liquid crystal cell tends to be thin. There is this. In addition, in order to improve visibility by eliminating reflection and light scattering at the interface, there is a tendency for the front plate to be integrated with the liquid crystal display panel with an adhesive or an ultraviolet curable resin.

In the conventional liquid crystal display panel, since the front plate and the liquid crystal cell are thick, warping due to shrinkage of the polarizing plate is suppressed even in a high-temperature environment, but the recent thickness of the front plate as described above and the glass used in the liquid crystal cell tend to be thin. Accordingly, there is a problem in that the liquid crystal display panel is warped due to shrinkage of the polarizing plate in a high-temperature environment, and the case of the final product is not collected.

In order to suppress such bending of the liquid crystal display panel, a method of suppressing the bending of the liquid crystal display panel by changing the thickness of the polarizing plate disposed on the viewing side of the liquid crystal cell and the side opposite to the viewing side of the liquid crystal cell (back side) has been proposed. Is being developed. For example, in Japanese Patent Application Laid-Open No. 2012-58429 (Patent Document 1), the thickness of the polarizing film (polarizer referred to in the present invention) of a polarizing plate disposed on the viewing side of the liquid crystal cell is set to be polarized light disposed on the rear side of the liquid crystal cell. A method of suppressing warpage of a liquid crystal display panel by making it thinner than a film is described.

However, since the warpage of the liquid crystal display panel in a high-temperature environment is due to the contraction of the polarizing plate due to the thickness of the polarizer as described above, when the thickness of the polarizer of the polarizing plate disposed on the viewing side as in Patent Document 1 is made thin, especially visibility In the case of a liquid crystal display panel in which the front panel is integrated with an adhesive or an ultraviolet curable resin for improvement, warpage may occur, and the suppression of warpage is not necessarily satisfactory.

In addition, in Japanese Patent No. 4666430 (Patent Document 2), in a liquid crystal display device (a liquid crystal display panel referred to in the present invention) using a plastic substrate liquid crystal cell, the protective film constituting the polarizing plates on the visible side and the rear side of the liquid crystal cell It describes a liquid crystal display element in which the amount of warpage of a plastic substrate liquid crystal cell was suppressed by changing the thickness. According to this method, the purpose of suppressing the warpage of the liquid crystal cell was achieved, but when the front plate is integrated with the polarizing plate and placed in a high temperature environment to improve visibility, the method of changing the thickness of the protective film as in Patent Document 2 The liquid crystal cell may be warped due to heat shrinkage of, and there may be a problem in that the case of the final product is not collected.

The present invention has been made to solve the above conventional problems, the main object of which is a set of polarizing plates in which the amount of warpage in a high temperature environment is suppressed when a liquid crystal display panel is formed, and a front surface formed by bonding the set of polarizing plates to a liquid crystal cell. It is to provide a plate-integrated liquid crystal display panel.

In other words, the present invention is a front plate in which a front plate disposed on the viewing side of a liquid crystal cell and having a Young's modulus of 2 GPa or more and a side far from the liquid crystal cell is bonded to the front side polarizing plate through an ultraviolet curable resin or an adhesive. As a set of an integral polarizing plate and a rear polarizing plate disposed on the rear side of a liquid crystal cell, the front polarizing plate has a dimensional change rate in the absorption axis direction when heated at 85°C for 100 hours without being bonded to the front plate, It is a set of polarizing plates characterized in that it is greater than the rate of dimensional change in the direction of the absorption axis when the rear polarizing plate is heated at 85°C for 100 hours.

In the set of polarizing plates, the front-side polarizing plate is preferably a polarizing plate having a dimensional change rate of 1.2% or more, preferably 1.3% or more, in the direction of the absorption axis when heated at 85° C. for 100 hours without being bonded to the front plate. , The rear polarizing plate is preferably a polarizing plate having a dimensional change rate of 1.1% or less in the absorption axis direction when heated at 85°C for 100 hours.

In the set of polarizing plates, both the front-side polarizing plate and the rear-side polarizing plate have a structure in which a transparent protective film is laminated on at least one side of a polarizer made of a polyvinyl alcohol-based resin film, and at least one polarizing plate has a liquid crystal cell side. The transparent protective film to be formed may be a set of polarizing plates having an in-plane retardation.

In the set of polarizing plates, both of the front-side polarizing plate and the rear-side polarizing plate have a structure in which transparent protective films are laminated on both sides of a polarizer made of a polyvinyl alcohol-based resin film, and the polarizer constituting the front-side polarizing plate is a rear-side polarizing plate. It may be a set of polarizing plates thicker than the polarizer constituting a.

It is preferable that this rear-side polarizing plate has another optical film laminated on the side away from the liquid crystal cell.

In the front-side polarizing plate, it is preferable that the absorption axis thereof is in the direction of the short side of the liquid crystal cell, and the absorption axis of the rear-side polarizing plate is in the direction of the long side of the liquid crystal cell.

In the present invention, a polarizing plate integrated with a front plate comprising a set of polarizing plates and a liquid crystal cell is provided on the viewing side of the liquid crystal cell, and a polarizing plate is adhered to the rear side of the liquid crystal cell. It is a front plate-integrated liquid crystal display panel having an absolute value of 0.5 mm or less, preferably 0.3 mm or less, in an absolute value, in which the rear polarizing plate constituting the set of is adhered and heated at 85° C. for 240 hours.

Advantageous Effects of Invention According to the present invention, warpage in a high-temperature environment in a liquid crystal display panel in which the front plate is integrated can be eliminated, and a front plate-integrated liquid crystal display panel can be obtained that is collected in the case of a final product in a high-temperature environment.

1 is a schematic cross-sectional view showing an example of a preferred layer structure in a set of polarizing plates according to the present invention.
2 is a schematic cross-sectional view showing an example of a preferred layer configuration in the front plate-integrated liquid crystal display panel according to the present invention.

Hereinafter, a set of polarizing plates according to the present invention and a front plate-integrated liquid crystal display panel using the same will be described appropriately using drawings, but the present invention is not limited to these embodiments.

First, the set of the polarizing plate of the present invention is composed of a front plate-integrated polarizing plate 40 and a rear polarizing plate 50. 1 shows a schematic cross-sectional view of an example of a preferred layer structure in a set of polarizing plates according to the present invention. Referring to Fig. 1, the front plate-integrated polarizing plate 40 constituting the set of polarizing plates of the present invention is disposed on the viewing side of the liquid crystal cell, and the front plate 10 disposed on the side far from the liquid crystal cell is It is bonded to the polarizing plate 30 through an ultraviolet curable resin or an adhesive 20. In addition, the front-side polarizing plate 30 is formed by bonding transparent protective films 35a and 35b of the front-side polarizing plate to both surfaces of the polarizer 37 of the front-side polarizing plate. In addition, the rear-side polarizing plate 50 is obtained by bonding transparent protective films 55a and 55b of the rear-side polarizing plate to both surfaces of the polarizer 57 of the rear-side polarizing plate.

The front plate 10 in the present invention is supposed to have a Young's modulus of 2 GPa or more because it serves to suppress or protect the warpage of the liquid crystal cell. The front plate 10 may be a single layer or a laminated one as long as it satisfies the Young's modulus. As described above, since the liquid crystal cell is disposed on the visible side of the liquid crystal cell, specifically on the outermost surface of the final product, it is assumed to be used outdoors or semi-outdoors. Therefore, from the viewpoint of durability, it is suitable to be composed of inorganic materials such as glass and tempered glass, and organic materials such as polycarbonate resin and acrylic resin. The front plate may be, for example, a tempered glass or film constituting a touch panel as long as it has a Young's modulus of 2 GPa or more. The touch panel method is not particularly limited, and includes a capacitive method, a surface acoustic wave method, a resistive film method, an electromagnetic induction method, an optical sensor method, an infrared method, and the like. The front plate 10 may have functions such as reflection prevention, contamination prevention, electromagnetic wave shielding, near-infrared shielding, color adjustment, or glass scattering. The front plate having such a function may be, for example, laminated on at least one side of the front plate at least one or more film layers having such a function. Such a multi-layered front plate may be prepared by directly applying an effective agent to impart the function to a substrate made of an organic or inorganic material as described above, or by bonding a separately prepared functional film having the above function. good.

The ultraviolet-curable resin or pressure-sensitive adhesive 20 that bonds the front plate 10 and the front-side polarizing plate 30 to each other is preferably a transparent one having a refractive index close to that of the front plate 10. By employing such an ultraviolet curable resin or pressure-sensitive adhesive, it is possible to improve visibility by eliminating reflection or scattering of light at the interface between the front plate and the polarizing plate.

As the ultraviolet curable resin, general ultraviolet curable liquids such as (meth)acrylic acid ester and epoxy resin can be used. In addition, as the pressure-sensitive adhesive, a base polymer made of acrylic polymer, silicone polymer, polyester, polyurethane, polyether, or the like can be used. Among them, it is preferable to use an acrylic pressure-sensitive adhesive having excellent optical transparency and high transparency, like an acrylic pressure-sensitive adhesive. Here, "(meth)acrylic acid ester" means that any of an acrylic acid ester and a methacrylic acid ester may be used, and in addition, "(meth)" when referred to as (meth)acrylate or the like has the same effect.

In the present invention, the front-side polarizing plate 30 made of the polarizer 37 has a rate of dimensional change in the stretching direction of the film (hereinafter also referred to as the absorption axis direction) when this is heated at 85° C. for 100 hours, preferably 1.2 % Or more and 3.0% or less, and more preferably 1.3% or more and 2.0% or less. When the upper limit of the dimensional change rate of the front-side polarizing plate is significantly exceeding 3.0%, there is a concern that the polarizing plate may be peeled off from the liquid crystal cell due to shrinkage of the polarizing plate in a high-temperature environment.

The rear-side polarizing plate 50 to which the polarizer 57 is applied preferably has a dimensional change rate of 0.1% or more and 1.1% or less, more preferably 0.5% or more and 1.1% or less, in the direction of the absorption axis when this is heated at 85° C. for 100 hours. Do. When the lower limit value of the dimensional change rate of the rear polarizing plate is too low than 0.1%, the optical properties are hindered, and there is a concern that a problem of low contrast may occur during liquid crystal display.

In the polarizing plate set of the present invention, the polarizer 37 constituting the front-side polarizing plate is a polarizer 57 of the rear-side polarizing plate constituting the rear-side polarizing plate 50 disposed on the rear side of the liquid crystal cell (hereinafter, polarizer ( 57)). The thickness of the polarizer 37 constituting the front-side polarizing plate is preferably 20 µm or more. The thickness of the polarizer 57 of the rear polarizing plate 50 of the liquid crystal cell is preferably 15 μm or less. Arranging a set of polarizing plates satisfying these conditions on both sides of the liquid crystal cell 60 is effective in suppressing the amount of warpage of the liquid crystal display panel (FIG. 2) in which the front plate is integrated.

As the polarizer used for the polarizing plates on the front side and the rear side, any suitable one can be used as long as the condition related to the dimensional change rate and/or the thickness of the polarizer are satisfied. As the polarizer, a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented is used. The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. This polyvinyl alcohol-based resin may also be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. Specific examples of polyvinyl alcohol-based resins and dichroic dyes include polyvinyl alcohol-based resins and dichroic dyes exemplified in Japanese Patent Laid-Open No. 2012-159778.

What formed such a polyvinyl alcohol-based resin into a film is used as a raw film of a polarizer. The method of forming a film of the polyvinyl alcohol-based resin is not particularly limited, and it can be formed by a known method such as the method described in Japanese Patent Laid-Open No. 2012-159778. The film thickness of the original film made of polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 1 to 150 µm. In consideration of the easiness of stretching, the film thickness is preferably 10 µm or more.

In addition, the polarizer is stretched, for example, in the step of uniaxially stretching the polyvinyl alcohol-based resin film, and dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye. It is prepared by treating the adsorbed polyvinyl alcohol-based resin film with an aqueous boric acid solution, followed by washing with water after treatment with the aqueous boric acid solution, and finally drying. The stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the manufacturing step of the polarizer may be performed according to the method described in Japanese Patent Laid-Open No. 2012-159778, for example.

Both the front-side polarizing plate 30 and the rear-side polarizing plate 50 defined in the present invention have a structure in which a transparent protective film is laminated on at least one side of the polarizer manufactured as described above. As this transparent protective film, what is formed from an appropriate transparent resin can be used. Specifically, it is preferable to use a polymer having excellent transparency, uniform optical properties, mechanical strength, and thermal stability. Examples of such transparent protective films include cellulose films such as triacetyl cellulose and diacetyl cellulose, polyester films such as polyethylene terephthalate, polyethylene isophthalate and polybutylene terephthalate, polymethyl(meth)acrylate and polyethyl Acrylic resin films such as (meth)acrylates, polycarbonate films, polyethersulfone films, polysulfone films, polyimide films, polyolefin films, polynorbornene films, etc. can be used, but limited to these It does not become.

The transparent protective films 35a and 35b applied to the front-side polarizing plate 30 and the transparent protective films 55a and 55b applied to the rear-side polarizing plate 50 may be the same or may be independent and different from each other. In addition, both or one of 35b or 55a, which is a transparent protective film near the liquid crystal cell, may be used. In the present invention, it is preferable that the transparent protective film formed on the liquid crystal cell side of at least one polarizing plate has an in-plane retardation.

The in-plane retardation of the transparent protective film can be provided by uniaxial stretching or biaxial stretching. The in-plane retardation value may be appropriately set in accordance with the type of liquid crystal cell to be applied, but is generally preferably set to 30 nm or more. The upper limit of the in-plane retardation value is not particularly limited, but, for example, about 300 nm is sufficient.

Prior to bonding to the polarizer, the transparent protective film may be subjected to an easily bonding treatment such as saponification treatment, corona treatment, primer treatment, and anchor coating treatment on the bonding surface. The thickness of the transparent protective film is usually in the range of about 5 to 200 µm, preferably 10 µm or more, preferably 80 µm or less, more preferably 40 µm or less.

On the surface of the transparent protective film, a surface treatment layer such as a hard coating layer, an antireflection layer, or an anti-glare layer may be formed as necessary. The hard coating layer is a surface treatment layer formed to prevent damage to the surface of the polarizing plate, and is mainly selected from an ultraviolet curable resin, such as acrylic or silicone resin, which has excellent adhesion and hardness to the transparent protective film. Can be formed on.

In addition, the antireflection layer is a surface treatment layer formed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be formed by a known method. The anti-glare layer is a surface treatment layer that is formed to prevent impairment of visibility caused by external light shining on the surface of the polarizing plate.For example, a roughening method such as a sandblast method or an embossing method, or a UV-curable resin mixed with transparent fine particles In general, the transparent protective film is formed such that the surface of the transparent protective film has an uneven configuration.

A polarizing plate is obtained by bonding the transparent protective film to at least one surface of a polarizer. As the polarizing plate, the transparent protective film may be bonded to both surfaces of a polarizer. The bonding of the polarizer and the transparent protective film is not particularly limited, but can be performed using an adhesive or pressure-sensitive adhesive made of an epoxy polymer. Such an adhesive layer or a pressure-sensitive adhesive layer is formed as a coating dry layer or the like of an aqueous solution, but when the aqueous solution is adjusted, other additives or catalysts such as an acid may be added as necessary.

In the present invention, the polarizing plate can be used by laminating one or two or more optical layers exhibiting different optical functions at the time of use. The optical layer is not particularly limited, and examples thereof include a reflective layer, a semi-transmissive reflective layer, a retardation plate, and a brightness enhancing film. An elliptically polarizing plate or circular polarizing plate in which a retardation plate is further stacked on a polarizing plate made of the polarizer and a transparent protective film, a polarizing plate in which one of the polarizing plates made of the polarizer and a transparent protective film is a viewing angle compensation film, or from the polarizer and the transparent protective film to the rear polarizing plate It can also be set as the polarizing plate in which the brightness improvement film is further laminated.

As for the retardation plate, a λ plate (1/2 λ plate or 1/4 λ plate) capable of forming a composite polarizing plate in an elliptically polarized or circularly polarized mode used in an image display device for mobile applications is laminated on the protective film to be effective. Is used. The composite polarizing plate in the elliptically polarized or circularly polarized mode has a function of changing to elliptically polarized light or circularly polarized light when the incident polarization direction is linearly polarized light, and to linearly polarized light when the incident polarization direction is elliptically polarized light or circularly polarized light. Particularly, as a retardation plate capable of changing elliptically polarized light or circularly polarized light into linearly polarized light and linearly polarized light into elliptically polarized light or circularly polarized light, what is called a 1/4λ plate is used. In addition, the 1/2λ plate has a function of changing the direction of linearly polarized light.

Specific examples of the retardation plate include polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polyolefin such as polypropylene, polyarylate, polyamide, polyolefin, polynorbornene, etc. A stretched film obtained by stretching a selected polymer is illustrated. Such a stretched film may be processed by an appropriate method such as uniaxial or biaxial. Further, it may be a birefringent film in which the refractive index in the thickness direction of the film is controlled by applying a shrinking force and/or a stretching force under adhesion to the heat-shrinkable film.

The luminance enhancing film is used for the purpose of improving luminance in a liquid crystal display device, for example, a reflective polarization separating sheet designed to generate anisotropy in the reflectance by stacking a plurality of thin films having different refractive index anisotropy. An alignment film of a steric liquid crystal polymer and a circularly polarized light separation sheet in which the alignment liquid crystal layer is supported on a film substrate, etc. are mentioned.

In the present invention, as for the rear-side polarizing plate 50, it is preferable to use one or two or more layers of optical layers exhibiting different optical functions on the side away from the liquid crystal cell.

The various optical layers are integrated with a polarizing plate using a pressure-sensitive adhesive or an adhesive, but the pressure-sensitive adhesive or adhesive used therefor is not particularly limited, and an appropriate one may be selected and used. It is preferable to use a pressure-sensitive adhesive from the viewpoint of simplicity of bonding operation and prevention of occurrence of optical distortion. The pressure-sensitive adhesive is not particularly limited, and for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether, or the like can be used as a base polymer. Among them, like acrylic pressure-sensitive adhesives, it has excellent optical transparency, maintains moderate wettability or cohesiveness, has excellent adhesion to the substrate, and further has heat resistance, and does not cause peeling problems such as lifting or peeling under a high temperature environment. It is preferable to select and use those that do not.

In addition, the pressure-sensitive adhesive layer may contain fine particles for exhibiting light scattering as necessary, and fillers made of glass fibers, glass beads, resin beads, metal powders or other inorganic powders, pigments or colorants, antioxidants, and ultraviolet absorbers. Etc. may be mixed. Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex salt compounds.

A pressure-sensitive adhesive layer may be formed on the transparent protective film constituting the polarizing plate or the optical layer formed on the polarizing plate to adhere to other members such as a liquid crystal cell. The pressure-sensitive adhesive layer can be formed with a conventional appropriate pressure-sensitive adhesive such as acrylic. In particular, from the viewpoint of preventing peeling in high temperature environments, reducing optical properties due to differences in thermal expansion, or preventing warping of an integrated front panel liquid crystal display panel, and further forming a high-quality and durable liquid crystal imaging device, an adhesive having excellent heat resistance It is preferably a layer. The pressure-sensitive adhesive layer may be formed on a necessary surface as necessary. For example, if referring to a transparent protective film of a polarizing plate composed of a polarizer and a transparent protective film, an adhesive layer may be formed on one or both surfaces of the transparent protective film as necessary. In addition, for the pressure-sensitive adhesive layer, suitable ones such as acrylic, silicone, polyester, polyurethane, polyether, and rubber can be used.

In the case where the pressure-sensitive adhesive layer formed on the polarizing plate or the optical member is exposed on the surface, it is preferable to temporarily cover the pressure-sensitive adhesive layer with a separator for the purpose of preventing contamination or the like, while the pressure-sensitive adhesive layer is actually used. The separator can be formed by a method of forming a release coat with an appropriate release agent such as silicon-based, long-chain alkyl-based, fluorine-based or molybdenum sulfide, if necessary, on an appropriate thin leaf body in accordance with the transparent protective film or the like.

In the set of polarizing plates of the present invention described above, the angle formed by the short side of the liquid crystal cell and the absorption axis of the front-side polarizing plate 30 is usually within ±45 degrees, and preferably within ±10 degrees. The angle formed by the long side of the liquid crystal cell and the absorption axis of the rear polarizing plate is usually within ±45 degrees, and preferably within ±10 degrees. It is more preferable that the front side polarizing plate 30 has its absorption axis substantially parallel to the short side direction of the liquid crystal cell, and the rear side polarizing plate preferably has its absorption axis substantially parallel to the long side direction of the liquid crystal cell.

Next, a front plate-integrated liquid crystal display panel according to the present invention will be described. In the front plate-integrated liquid crystal display panel according to the present invention, the front plate-integrated polarizing plate 40 and the rear-side polarizing plate 50 are bonded to a liquid crystal cell. An example of a preferred layer structure is shown in a schematic cross-sectional view. Referring to FIG. 2, in the front plate integrated liquid crystal display panel 80 of the present invention, the front plate integrated polarizing plate 40 constituting the set of polarizing plates of FIG. 1 is placed on the viewer side of the liquid crystal cell 60, and the rear side polarizing plate. It is a configuration in which 50 is bonded to the back side of the liquid crystal cell 60 via an adhesive, respectively.

As the pressure-sensitive adhesive used for bonding the liquid crystal cell 60 and the set of the polarizing plate, a pressure-sensitive adhesive made of an acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is preferable.

The front plate-integrated liquid crystal display panel 80 of the present invention has an absolute amount of warpage of 0.5 mm or less, preferably 0.3 mm or less, when heated at 85° C. for 240 hours. Accordingly, warpage in a high-temperature environment is suppressed, resulting in a front plate-integrated liquid crystal display panel that is collected in the case of the final product.

Example

Hereinafter, examples and comparative examples are shown to describe the present invention more specifically, but the present invention is not limited thereto. In the examples,% and parts indicating content or amount used are based on weight unless otherwise specified.

[Example 1]

(1) Fabrication of a set of polarizing plates

The front side polarizing plate (polarizing plate 1) was produced as follows. First, a polyvinyl alcohol film with a thickness of 60 µm (average polymerization degree of about 2,400, saponification degree of 99.9 mol% or more) is uniaxially stretched about 5 times by dry stretching, and immersed in pure water at 60° C. for 1 minute while maintaining the tension Then, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28°C for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72°C for 300 seconds. Subsequently, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer having a thickness of 23 μm in which iodine is adsorbed and oriented in a polyvinyl alcohol film. Next, in one side of this polarizer, 3 parts of a carboxyl group-modified polyvinyl alcohol (trade name "KL-318" obtained from Kuraray Co., Ltd.) was dissolved in 100 parts of water, and a water-soluble epoxy resin polyamide was dissolved in the aqueous solution. An epoxy-based adhesive containing 1.5 parts of an epoxy-based additive (trade name "Sumirez Resin 650(30)" obtained from Taoka Chemical Industries, Ltd., an aqueous solution having a solid content of 30%) was applied, and a thickness of 40 μm as a transparent protective film The triacetyl cellulose film of [manufactured by Konica Minolta Opto Co., Ltd., brand name "KC4UY"] was bonded, and on the opposite side, the adhesive was used to form a norbornene-based resin and an unstretched film [manufactured by Nippon Xeon Co., Ltd. The brand name "ZEONOR"] was joined.

The back side polarizing plate (polarizing plate 2) was produced as follows. First, a 30 μm-thick polyvinyl alcohol film (average polymerization degree of about 2,400, saponification degree of 99.9 mol% or more) is uniaxially stretched by about 5 times by dry stretching, and immersed in pure water at 60° C. for 1 minute while maintaining a tension state. Then, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28°C for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72°C for 300 seconds. Subsequently, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer having a thickness of 11 μm in which iodine is adsorbed and oriented to a polyvinyl alcohol film. With respect to this polarizer, a transparent protective film was bonded in the same manner as in the front-side polarizing plate. Thereafter, a 5 µm thick adhesive material [brand name "#L2" manufactured by Lintec Co., Ltd.] was bonded to the side of the TAC, and a 26 µm-thick luminance enhancing film (brand name "Advanced Polarized Film, Version 3 manufactured by 3M" ") was joined.

Regarding the front-side polarizing plate and the rear-side polarizing plate produced in the above (1), the rate of dimensional change of the polarizing plate in a high-temperature environment was measured by the following method. First, each produced polarizing plate was cut into a square or rectangular shape having a length direction of 30 mm to 50 mm and a width direction of 20 to 50 mm, and allowed to stand in an environment at 85°C for 100 hours. Next, measure the dimension (L ₀ ) in the longitudinal direction (absorption axis direction) at the time of cutting and the dimension (L ₁ ) in the longitudinal direction after standing in a high temperature environment. It measured using, and the dimensional change rate (%) was calculated|required from the following formula. The results were shown in the column of "the dimensional change rate of the polarizing plate" in Table 1.

Dimensional change rate=[(L ₀ -L ₁ )/L ₀ ]×100

(2) Fabrication of front panel integrated liquid crystal display panel

The set of polarizing plates produced in (1) was bonded to a liquid crystal cell to produce a front plate-integrated liquid crystal display panel. On the surface of the polarizing plate produced in (1) on the side of the norbornene-based resin "ZEONOR", a pressure-sensitive adhesive having a thickness of 20 µm (brand name "P-3132" manufactured by Lintec Co., Ltd.) was applied, and the front polarizing plate was placed in a liquid crystal cell. It was cut into a size of 5 inches so that the absorption axis of the polarizer was parallel with respect to the short side of, and the rear polarizing plate was cut into a size of 5 inches so that the absorption axis of the polarizer was parallel to the long side of the liquid crystal cell. Subsequently, the cut polarizing plates were bonded to the liquid crystal cell from the adhesive side, and an ultraviolet-curable optical elastic resin (trade name "Super View Resin" manufactured by Dexerials Co., Ltd.) was applied to the triacetylcellulose film side of the front polarizing plate. And a front plate (trade name "Gorilla" manufactured by Corning) having a Young's modulus of 70 GPa and a thickness of 0.55 mm was laminated thereon. Thereafter, ultraviolet rays were irradiated from the front plate side ["D bulb" manufactured by Fusion UV Systems Co., Ltd., an accumulated light quantity of 1200 mJ/cm 2) to prepare a front plate-integrated liquid crystal cell.

About the front plate-integrated liquid crystal display panel produced in the above (2), the amount of warpage in a high-temperature environment was measured by the following method. First, the produced front plate-integrated liquid crystal display panel was allowed to stand for 240 hours in an environment of 85° C., and then placed on a measuring table of “NEXIV VMR-12072”, a two-dimensional measuring instrument manufactured by Nikon Co., Ltd. with the front plate as the upper side. Next, focus on the surface of the measuring table, and based on it, focus on the four corners, the center of each of the four sides of the front panel integrated liquid crystal display panel, and the center of the front panel integrated liquid crystal display panel, and from the reference focus After measuring the distance, the distance from the measuring table was the absolute value and the longest distance was taken as the amount of warpage. The measurement result was shown in the column of "the amount of warping" in Table 1.

[Example 2]

(1) Fabrication of a set of polarizing plates

A polyvinyl alcohol aqueous solution was applied on the base film and dried to prepare a laminated film serving as a raw material for manufacturing a polarizer. Here, a polypropylene film having a thickness of 110 µm and a melting point of 163°C was used as the base film.

Next, acetoacetyl group-modified polyvinyl alcohol powder with an average degree of polymerization of 1,100 and a degree of saponification of 99.5 mol% (trade name "Gosefimer Z-200" manufactured by Japan Synthetic Chemical Industry Co., Ltd.) was dissolved in hot water at 95°C. An aqueous solution of% concentration was prepared. To this aqueous solution, a water-soluble polyamide epoxy resin (trade name "Sumirez Resin 650" manufactured by Taoka Chemical Industries, Ltd., an aqueous solution having a solid content concentration of 30%) was mixed in a ratio of 5 parts per 6 parts solid content of polyvinyl alcohol, It was set as the coating liquid for primers.

Then, after corona treatment was previously performed on the base film made of polypropylene, the coating liquid for primer was coated on the corona treated surface with a microgravure coater and dried at 80° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm. .

Next, polyvinyl alcohol powder with an average degree of polymerization of 2,400 and a saponification degree of 98.0 to 99.1 mol% (trade name "PVA124" obtained from Kuraray Co., Ltd.) was dissolved in hot water at 95°C to obtain an 8% aqueous polyvinyl alcohol solution. Prepared. The obtained aqueous solution was coated on the primer layer of the base film at room temperature using a lip coater and dried at 80° C. for 20 minutes to prepare a laminate film consisting of a base film/primer layer/polyvinyl alcohol layer.

The obtained laminated film was stretched uniaxially at a temperature of 160°C and 5.8 times at the free end. The total thickness of the laminated stretched film thus obtained was 28.5 µm, and the thickness of the polyvinyl alcohol layer was 5.0 µm.

The obtained laminated stretched film was immersed in an aqueous solution having a weight ratio of water/iodine/potassium iodide of 100/0.35/10 at 26°C for 90 seconds, dyed, and washed with pure water at 10°C. Next, this laminated film was immersed in an aqueous solution having a weight ratio of water/boric acid/potassium iodide of 100/9.5/5 at 76°C for 300 seconds to crosslink polyvinyl alcohol. Subsequently, it washed with pure water at 10°C for 10 seconds, and finally dried at 80°C for 200 seconds. By the above operation, a polarizing laminated film in which a polarizer made of a polyvinyl alcohol layer in which iodine is adsorbed and oriented is formed on a polypropylene base film was produced.

3 parts of carboxyl group-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd. with respect to 100 parts of water on the opposite side (polarizer side) of the polarizing laminated film produced above Epoxy by dissolving and adding 1.5 parts of polyamide epoxy resin, a water-soluble epoxy resin, to the aqueous solution [trade name "Sumirez Resin 650(30)" obtained from Taoka Chemical Industries, an aqueous solution having a solid content concentration of 30%) TAC/polyvinyl alcohol system by applying an adhesive and bonding a 25 μm-thick triacetyl cellulose film (TAC) (trade name "KC2UA" manufactured by Konica Minolta Opto Co., Ltd.) as a transparent protective film and peeling only the base film A polarizing plate composed of a polarizer/primer layer was obtained.

Next, a UV-curable adhesive containing an epoxy compound and a photocationic polymerization initiator was applied to the side of the primer, and a norbornene-based resin and non-stretched film [brand name "ZEONOR" manufactured by Nippon Xeon Co., Ltd. By irradiating ultraviolet rays from the side of the ene-based resin ("D bulb" manufactured by Fusion UV Systems, Inc. of 1200 mJ/cm 2) and curing the adhesive, the TAC/polyvinyl alcohol-based polarizer/primer layer/norbornene-based resin The polarizing plate (3) was obtained.

Thereafter, a 5 µm thick adhesive material [brand name "#L2" manufactured by Lintec Co., Ltd.] was bonded to the side of the TAC, and a 26 µm-thick luminance enhancing film (brand name "Advanced Polarized Film, Version 3" manufactured by 3M) was bonded to the TAC side. ) Was joined.

Regarding the polarizing plate 3 manufactured above, the polarizing plate was cut into a square or rectangular size of 30 mm to 50 mm in the length direction and 20 to 50 mm in the width direction, and the dimensional change rate (%) was determined in the same manner as in Example 1. Saved.

After removing the pressure-sensitive adhesive on the TAC side of the polarizing plate 2 and the brightness enhancing film from the front polarizing plate, the pressure-sensitive adhesive was applied to the surface of the norbornene resin "ZEONOR" side of the polarizing plate 3 as a rear polarizing plate, and then applied to the liquid crystal cell. Except for bonding, a front plate-integrated liquid crystal cell was produced in the same manner as in Example 1, and the amount of warpage in a high-temperature environment was measured. The results were shown in the column of "the amount of warpage" in Table 1.

[Example 3]

As the front-side polarizing plate to be bonded to the liquid crystal cell, the same as in Example 1, except that the adhesive on the side of the TAC side of the rear-side polarizing plate (the polarizer having a thickness of 11 μm) used in Example 1 and the brightness enhancing film were removed. Thus, a front plate-integrated liquid crystal display panel was produced, and the amount of warpage in a high-temperature environment was measured. The results were shown in the column of "the amount of warpage" in Table 1.

[Example 4]

(1) Fabrication of a set of polarizing plates

The front side polarizing plate was produced as follows. First, a 75 µm-thick polyvinyl alcohol film (average polymerization degree of about 2,400, saponification degree of 99.9 mol% or more) is uniaxially stretched about 5 times by dry stretching, and immersed in pure water at 60° C. for 1 minute while maintaining a tension state. Then, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28°C for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72°C for 300 seconds. Subsequently, after washing with pure water at 26° C. for 20 seconds, it was dried at 65° C. to obtain a polarizer having a thickness of 28 μm in which iodine is adsorbed and oriented to a polyvinyl alcohol film. Next, in one side of this polarizer, 3 parts of a carboxyl group-modified polyvinyl alcohol (trade name "KL-318" obtained from Kuraray Co., Ltd.) was dissolved in 100 parts of water, and a water-soluble epoxy resin polyamide was dissolved in the aqueous solution. An epoxy-based adhesive containing 1.5 parts of an epoxy-based additive (trade name "Sumirez Resin 650(30)" obtained from Taoka Chemical Industries, Ltd., an aqueous solution having a solid content of 30%) was applied, and a thickness of 40 μm as a transparent protective film The triacetyl cellulose film [the trade name "KC4UY" manufactured by Konica Minolta Opto Corporation) was bonded to obtain a polarizing plate composed of a TAC/PVA layer.

Thereafter, for the polarizing plate prepared above, the polarizing plate was cut into a square or rectangular size of 30 mm to 50 mm in the length direction and 20 to 50 mm in the width direction, and the dimensional change rate (%) was calculated in the same manner as in Example 1. .

The back side polarizing plate was created as follows. First, an aqueous solution of polyvinyl alcohol was applied on a base film and dried to prepare a laminated film serving as a raw material for manufacturing a polarizer. Here, a polypropylene film having a thickness of 110 µm and a melting point of 163°C was used as the base film.

Next, acetoacetyl group-modified polyvinyl alcohol powder with an average degree of polymerization of 1,100 and a degree of saponification of 99.5 mol% (trade name "Gosefimer Z-200" manufactured by Japan Synthetic Chemical Industry Co., Ltd.) was dissolved in hot water at 95°C. An aqueous solution of% concentration was prepared. As a crosslinking agent in this aqueous solution, a water-soluble polyamide epoxy resin (trade name "Sumirez Resin 650" manufactured by Taoka Chemical Industry Co., Ltd., an aqueous solution having a solid content of 30%) was mixed in a ratio of 5 parts per 6 parts of solid content of polyvinyl alcohol. And a primer coating solution.

Then, after corona treatment was previously performed on the base film made of polypropylene, a primer coating solution was coated on the corona treated surface with a microgravure coater and dried at 80° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

Next, polyvinyl alcohol powder with an average degree of polymerization of 2,400 and a saponification degree of 98.0 to 99.1 mol% (trade name "PVA124" obtained from Kuraray Co., Ltd.) was dissolved in hot water at 95°C to obtain an 8% aqueous polyvinyl alcohol solution. Prepared. The obtained aqueous solution was coated on the primer layer of the base film at room temperature using a lip coater and dried at 80° C. for 20 minutes to prepare a laminate film consisting of a base film/primer layer/polyvinyl alcohol layer.

The obtained laminated film was stretched uniaxially at a temperature of 160°C and 5.8 times at the free end. The total thickness of the laminated stretched film thus obtained was 28.5 µm, and the thickness of the polyvinyl alcohol layer was 5.0 µm.

The obtained laminated stretched film was immersed in an aqueous solution having a weight ratio of 100/0.35/10 of water/iodine/potassium iodide at 26°C for 90 seconds to dye, and then washed with pure water at 10°C. Next, this laminated film was immersed in an aqueous solution having a weight ratio of water/boric acid/potassium iodide of 100/9.5/5 at 76°C for 300 seconds to crosslink polyvinyl alcohol. Subsequently, it washed with pure water at 10°C for 10 seconds, and finally dried at 80°C for 200 seconds. By the above operation, a polarizing laminated film in which a polarizer made of a polyvinyl alcohol layer in which iodine is adsorbed and oriented is formed on a polypropylene base film was produced.

3 carboxyl group-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd. with respect to 100 parts of water on the opposite surface (polarizer surface) of the polarizing laminate film produced above. Partly dissolved, and 1.5 parts of a water-soluble epoxy resin polyamide epoxy resin additive [trade name "Sumirez Resin 650(30)" obtained from Taoka Chemical Industries, an aqueous solution having a solid content concentration of 30%) was added to the aqueous solution. TAC/polyvinyl alcohol by applying an epoxy-based adhesive and bonding a 25 µm-thick triacetylcellulose film (TAC) (trade name "KC2UA" manufactured by Konica Minolta Opto Co., Ltd.) as a transparent protective film and peeling only the base film. A polarizing plate composed of a system polarizer/primer layer was obtained. Thereafter, a 5 µm thick adhesive material [brand name "#L2" manufactured by Lintec Co., Ltd.] was bonded to the side of the TAC, and a 26 µm-thick luminance enhancing film (brand name "Advanced Polarized Film, Version 3" manufactured by 3M) was bonded to the TAC side. ) Was joined.

Regarding the polarizing plate prepared above, the polarizing plate was cut into a square or rectangular size of 30 mm to 50 mm in the length direction and 20 to 50 mm in the width direction, and the dimensional change rate (%) was calculated in the same manner as in Example 1.

Thereafter, a 20 μm-thick pressure-sensitive adhesive (brand name "P-3132" manufactured by Lintec Co., Ltd.) was applied directly to the polarizer surface without a transparent protective layer, and then a front plate-integrated liquid crystal display panel was prepared in the same manner as in Example 1. It produced and measured the amount of warpage in a high-temperature environment. The results were shown in the column of "the amount of warpage" in Table 1.

[Comparative Example 1]

A front plate-integrated liquid crystal display panel was produced in the same manner as in Example 1, except that the front side polarizing plate (the polarizer having a thickness of 23 µm) used in Example 1 was used as the back side polarizing plate to be bonded to the liquid crystal cell, The amount of warpage in a high-temperature environment was measured. The results were shown in the column of "the amount of warpage" in Table 1.

[Comparative Example 2]

As a front-side polarizing plate to be bonded to a liquid crystal cell, a rear-side polarizing plate (with a polarizer having a thickness of 11 µm) removed from the TAC side of the TAC side used in Example 1 and a luminance-enhancing film is used, and the back side to be bonded to the liquid crystal cell As the polarizing plate, a front plate-integrated liquid crystal display panel was produced in the same manner as in Example 1, except that the front-side polarizing plate used in Example 1 (the thickness of the polarizer was 23 µm) was used, and the amount of warpage in a high-temperature environment was measured. did. The results were shown in the column of "the amount of warpage" in Table 1.

As is clear from the results of Table 1, in Examples 1 to 4, in the front plate-integrated liquid crystal display panels, the rate of dimensional change in the absorption axis direction when heated at 85° C. for 100 hours at 85° C. of the front side of the liquid crystal cell was It is a combination larger than the rate of dimensional change in the direction of the absorption axis when the side polarizing plate is heated at 85°C for 100 hours.

In Examples 1 to 4, the front plate-integrated liquid crystal display panel has a dimensional change rate of 1.2% or more in the absorption axis direction when the polarizing plate on the front side of the liquid crystal cell is heated at 85°C for 100 hours, and the rear polarizing plate is 85 It is a combination that satisfies that the rate of dimensional change in the absorption axis direction when heated at DEG C for 100 hours is 1.1% or less. In addition, in Examples 1, 2, and 4, the polarizer constituting the front-side polarizing plate is thicker than the polarizer constituting the rear-side polarizing plate.

In Examples 1 to 4, the amount of warpage of the front plate-integrated liquid crystal display panel after standing in a high temperature environment for 240 hours is 0.5 mm or less in absolute value.

Advantageous Effects of Invention According to the present invention, warpage in a high-temperature environment in a liquid crystal display panel in which the front plate is integrated can be eliminated, and a front plate-integrated liquid crystal display panel can be obtained that is collected in the case of a final product in a high-temperature environment.

10: front panel,
20: adhesive or ultraviolet curable resin,
30: front side polarizing plate,
35a, 35b: transparent protective film of the front polarizing plate,
37: polarizer of the front side polarizing plate,
40: front plate integrated polarizing plate,
50: back side polarizing plate,
55a, 55b: transparent protective film of the rear polarizing plate,
57: polarizer of the rear polarizing plate,
60: liquid crystal cell,
80: Front panel integrated liquid crystal display panel.

Claims (7)

The front plate, which is arranged on the visible side of the liquid crystal cell, has a Young's modulus of 2 Gpa or more, and is far from the liquid crystal cell, is bonded to the front polarizing plate through an ultraviolet curable resin or adhesive. As a set of a front plate integrated polarizing plate and a rear polarizing plate disposed on the rear side of the liquid crystal cell,
The front-side polarizing plate has a dimensional change rate in the absorption axis direction when heated at 85° C. for 100 hours without being bonded to the front plate, in the absorption axis direction when heated at 85° C. for 100 hours. Greater than the rate of dimensional change,
The front polarizing plate has a dimensional change rate of 1.2% or more and 3.0% or less in the direction of the absorption axis when heated at 85° C. for 100 hours without being bonded to the front plate,
The rear polarizing plate has a dimensional change rate of 1.1% or less in the absorption axis direction when heated at 85° C. for 100 hours,
The front-side polarizing plate is characterized in that the angle of the absorption axis formed with the short side of the liquid crystal cell is ±10 degrees or less, and the rear-side polarizing plate is characterized in that the angle formed by the absorption axis of the long side of the liquid crystal cell is ±10 degrees or less A set of polarizing plates to make. delete The method of claim 1, wherein both the front-side polarizing plate and the rear-side polarizing plate have a structure in which a transparent protective film is laminated on at least one side of a polarizer made of a polyvinyl alcohol-based resin film, and the polarizer constituting the front-side polarizing plate is And a set of polarizing plates that are thicker than a polarizer constituting the rear polarizing plate. 4. A set of polarizing plates in which the transparent protective film formed on the cell side has an in-plane retardation. The set of polarizing plates according to claim 1 or 3, wherein, in the rear polarizing plate, another optical film is laminated on a side away from the liquid crystal cell. delete A set of polarizing plates according to claim 1 or 3 and a liquid crystal cell are provided,
On the viewing side of the liquid crystal cell, a front plate-integrated polarizing plate constituting the set of polarizing plates is adhered to the polarizing plate side, and a rear polarizing plate constituting the set of polarizing plates is adhered to the rear side of the liquid crystal cell,
A front plate-integrated liquid crystal display panel characterized in that the amount of warpage when heated at 85° C. for 240 hours is 0.5 mm or less in absolute value.

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