TWI622817B - Polarizing plate set and liquid crystal panel - Google Patents

Abstract

The invention provides a set of polarizing plates capable of suppressing warping of a liquid crystal panel under a high temperature environment, and a liquid crystal panel formed by bonding the set of polarizing plates to a liquid crystal cell.

The set of polarizing plates of the present invention is a set of viewing-side polarizing plates arranged on the viewing side of the liquid crystal cell and a set of back-side polarizing plates arranged on the back side of the liquid crystal cell. The structure of the bright film and the absorption-type polarizing plate is disposed on the back side of the liquid crystal cell, and the distance from the surface in contact with the liquid crystal cell to the brightening film is 100 μm or less, and the viewing-side polarizing plate 100 is heated at 85 ° C. The ratio of the dimensional change rate in the absorption axis direction after 1 hour to the dimensional change rate in the absorption axis direction after heating the back side polarizer at 85 ° C. for 100 hours was more than 1 and 1.4 or less.

Description

Polarizer set and LCD panel

The present invention relates to a set of polarizing plates for suppressing warpage of a liquid crystal panel under a high temperature environment, and a liquid crystal panel using the same.

In recent years, liquid crystal displays with low power consumption, low voltage operation, and light weight are rapidly gaining popularity as information display devices such as mobile phones, portable information terminals, computer monitors, and televisions. With the development of liquid crystal technology, various modes of liquid crystal displays have been proposed, and the problems of liquid crystal displays with response speed or contrast and narrow viewing angles have been gradually solved. In addition, with the spread of liquid crystal displays for mobile devices, thinner and lighter liquid crystal panels are also required.

Along with the thinning of the liquid crystal panel, the liquid crystal panel is warped due to the shrinkage of the polarizing plate attached to the liquid crystal cell under a high temperature environment, which causes problems such as being unable to be accommodated in the frame of the final product.

In order to suppress the warpage of this liquid crystal display panel, conventionally, it has been developed to suppress the liquid crystal display panel by changing the thickness of the polarizing plate disposed on the viewing side of the liquid crystal cell and on the opposite side (back side) from the viewing side of the liquid crystal cell. Warping technique. For example, Japanese Patent Application Laid-Open No. 2012-58429 The paper (Patent Document 1) describes a thickness of a polarizing film (referred to as a polarizing film in the present invention) of a polarizing plate disposed on the viewing side of a liquid crystal cell, compared to a polarizing film disposed on the back side of a liquid crystal cell. Thinner method to suppress warpage of the liquid crystal display panel.

In addition, Japanese Patent Application Laid-Open No. 2013-37115 (Patent Document 2) proposes a polarizing film (referred to as a polarizing film in the present invention) included in the optical laminated body on the viewing side, and is arranged relatively on the viewing side. The polarizing film included in the optical laminated body on the opposite side is thicker than 5 μm to prevent warping of the liquid crystal panel. However, there is still much room for improvement in suppressing warpage of the liquid crystal panel.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-58429

[Patent Document 2] Japanese Patent Laid-Open No. 2013-37115

An object of the present invention is to provide a set of polarizing plates capable of suppressing warpage of a liquid crystal panel under a high temperature environment, and a liquid crystal panel formed by bonding the set of polarizing plates to a liquid crystal cell.

The present invention provides a set of polarizing plates, which is a set of a viewing-side polarizing plate arranged on the viewing side of a liquid crystal cell and a back-side polarizing plate arranged on the back side of the liquid crystal cell, which is characterized by: a back-side polarizing plate It has a laminated structure with a brightness enhancement film and an absorption-type polarizing plate. The distance from the liquid crystal cell to the brightness enhancement film is 100 μm or less. The dimensional change rate in the absorption axis direction after heating the polarizing plate at 85 ° C for 100 hours, and The ratio of the dimensional change rate in the absorption axis direction after the back side polarizing plate was heated at 85 ° C for 100 hours was more than 1 and 1.4 or less.

In order to suppress warpage, the thickness of the polarizing film included in the viewing-side polarizing plate is preferably larger than the thickness of the polarizing film of the absorption-type polarizing plate included in the back-side polarizing plate. In addition, in the absorptive polarizing plate included in the back-side polarizing plate, in order to reduce the distance between the liquid crystal cell and the brightness enhancement film, it is preferable to have a structure having a protective film on only one side.

It is preferable that the viewing-side polarizing plate is such that the absorption axis thereof becomes the short-side direction of the liquid crystal cell, and the rear-side polarizing plate is such that the absorption axis thereof becomes the long-side direction of the liquid crystal cell.

In addition, the present invention also provides a liquid crystal panel, which is characterized by comprising: the above-mentioned set of polarizing plates and a liquid crystal cell; a viewing-side polarizing plate is attached to a viewing side of the liquid crystal cell; The amount of warpage of the polarizing plate after heating at 85 ° C. for 240 hours was 0.5 mm or less in absolute terms.

According to the present invention, warping of a liquid crystal panel in a high-temperature environment can be solved, and a liquid crystal panel that can be accommodated in a frame of a final product even in a high-temperature environment can be obtained.

30‧‧‧view side polarizer

31a, 31b, 51‧‧‧ protective film

32, 52‧‧‧ polarizing film

33, 53‧‧‧ Adhesive layer

35‧‧‧Surface treatment layer

50‧‧‧ Absorptive Polarizer

54‧‧‧ Adjacent layer

60‧‧‧Back side polarizer

61‧‧‧brightening film

FIG. 1 is a schematic cross-sectional view showing an example of a preferred layer configuration of a set of polarizing plates of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of a preferred layer configuration of a set of polarizing plates of the present invention.

Fig. 3 is a schematic cross-sectional view showing an example of a reflective polarizing film used in the present invention.

In the following, the set of the polarizing plate of the present invention and the liquid crystal panel using the same are appropriately described using the drawings, but the present invention is not limited to these embodiments.

The set of polarizing plates of the present invention is composed of a viewing-side polarizing plate 30 and a back-side polarizing plate 60. Referring to FIG. 1, the layer configurations of the viewing-side polarizing plate 30 and the back-side polarizing plate 60 according to the present invention will be described. In FIG. 1, protective films 31 a and 31 b are attached to both sides of the viewing-side polarizing plate 30 on the polarizing film 32. It is also useful to form a surface treatment layer on the surface of the protective film 31 a on the side opposite to the bonding surface of the polarizing film 32. Regarding the back-side polarizing plate 60, the absorption-type polarizing plate 50 is formed by bonding a protective film 51 to at least one surface of the polarizing film 52. Furthermore, the brightness enhancement film 61 is laminated on the absorption-type polarizing plate 50 through the adhesive layer 54 to form a back-side polarizing plate 60. These polarizing plates are respectively adhered to the liquid crystal cell through the adhesive layers 33 and 53 to form a liquid crystal panel.

In the aforementioned back-side polarizing plate, the distance from the liquid crystal cell to the brightness enhancement film 61 is 100 μm or less, preferably 80 μm or less, and particularly preferably 60 μm or less. The lower limit is not particularly limited, and is usually 5 μm or more. It is typically 10 μm or more. In addition, the dimensional change rate in the absorption axis direction after heating the viewing-side polarizing plate 30 at 85 ° C. for 100 hours and the dimensional change rate in the absorption axis direction after heating the front-side polarizing plate 60 at 85 ° C. for 100 hours. The ratio is more than 1 and 1.4 or less, preferably 1.01 or more and 1.4 or less, and particularly preferably 1.05 or more and 1.3 or less. In the present invention, the distance from the liquid crystal cell to the brightness enhancement film means the surface of the polarizing plate on the back side that is in contact with the liquid crystal cell (for example, in FIGS. 1 to 2, the adhesive layer 53 is in contact with the liquid crystal cell). The surface is equivalent to this) to the liquid crystal cell side surface of the brightness enhancement film.

The amount of warpage of the liquid crystal panel is greatly affected by the brightness enhancement film disposed as the outermost layer from the liquid crystal cell. Therefore, by keeping the distance between the liquid crystal cell and the brightness enhancement film within the above range, and making the viewing-side polarizing plate 30 and the back-side polarizing plate 60 heated at 85 ° C. for 100 hours, the dimensional change rate in the absorption axis direction is as described above. Range to reduce the amount of warpage of the LCD panel.

In the present invention, since the brightness enhancement film is brought closer to the liquid crystal cell, the absorption-type polarizing plate 50 included in the back-side polarizing plate 60 is preferably configured to have a protective film only on one side of the polarizing film. In this way, by arranging the brightness-enhancing film near the liquid crystal cell, it is possible to reduce the influence of the force generated by the dimensional change of the brightness-enhancing film on the warpage of the liquid crystal panel.

Furthermore, it is preferable that the viewing-side polarizing plate has an absorption axis substantially parallel to the short-side direction of the liquid crystal cell, and the rear-side polarizing plate has an absorption axis that is substantially parallel to the long-side direction of the liquid crystal cell. The so-called substantially parallel is not limited to being strictly parallel, for example, polarized light The angle formed by the absorption axis of the plate and each side of the liquid crystal cell is preferably 5 ° or less, particularly preferably 3 ° or less, and even more preferably 1 ° or less. By adopting such an axis configuration, the warpage of the liquid crystal panel can be more significantly reduced.

In addition, the present invention also provides a liquid crystal panel in which the viewing-side polarizing plate 30 and the back-side polarizing plate 60 are laminated on a liquid crystal cell through an adhesive layer 33.

The following is a detailed description of the kit and components of the liquid crystal panel constituting the polarizing plate of the present invention. In addition, the polarizing film 32 included in the viewing-side polarizing plate and the polarizing film 52 included in the rear-side polarizing plate may be collectively referred to as a polarizing film, and the protective film 31 a and the protective film 31 b and the protective film 51 may be collectively referred to as a protective film.

[Polarizing film 32, 52]

The polarizing films 32 and 52 only need to satisfy the dimensional change rate and the thickness of the polarizing film, and any appropriate one can be used. A polarizing film is generally prepared through the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and boric acid A step of cross-linking a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed by an aqueous solution, and a step of washing with water after a cross-linking treatment of an aqueous solution of boric acid.

The polyvinyl alcohol-based resin can be produced by saponifying a polyvinyl acetate-based resin. Polyvinyl acetate resins are copolymers of vinyl acetate and other monomers copolymerizable with polyvinyl acetate, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate. Can be copolymerized with vinyl acetate Other mono-systems include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl aldehyde and polyvinyl acetal modified by aldehydes may be used. 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.

A film made of such a polyvinyl alcohol-based resin can be used as a base material film as a polarizing film. The method for forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a film can be formed by a generally known method. The film thickness of the polyvinyl alcohol-based embryo material film is, for example, about 10 to 100 μm, and preferably about 10 to 50 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film in the longitudinal direction may be performed before, simultaneously with, or after dyeing of the dichroic pigment. When longitudinal uniaxial stretching is performed after dyeing, the longitudinal uniaxial stretching may be performed before or during a boric acid treatment. Of course, the uniaxial stretching in the longitudinal direction may be performed in a plurality of stages shown here. The longitudinal uniaxial stretching system may be a method of uniaxial stretching between rollers having different peripheral speeds, or a method of uniaxial stretching using a hot roller. In addition, the longitudinal uniaxial stretching may be performed by dry stretching in the air, or by using a solvent such as water and wet stretching in a state where the polyvinyl alcohol resin film is swollen. Stretch out. The stretching ratio is usually about 3 to 8 times.

The dyeing of the polyvinyl alcohol resin film with a dichroic dye can be performed, for example, by immersing the polyvinyl alcohol resin film in an aqueous solution containing a dichroic dye. For dichroic pigments, specifically In terms of iodine or dichroic organic dyes can be used. It is preferable that the polyvinyl alcohol-based resin film be immersed in water to be swelled before the dyeing treatment.

When iodine is used as a dichroic dye, a method of dyeing is generally performed by dipping a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. The content of iodine in the aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. The immersion time (dyeing time) in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic organic dye is usually used for dyeing. The content of the dichroic organic dye in the aqueous solution is usually about 1 × 10 ^-4 to 10 parts by weight, preferably about 1 × 10 ^-3 to 1 part by weight, per 100 parts by weight of water. The dye aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution of the dichroic organic dye used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with a dichroic pigment is performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The content of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. When using iodine as a dichroic pigment, the boric acid-containing aqueous solution preferably contains Potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and particularly preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually about 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

After the boric acid treatment, the polyvinyl alcohol resin film is usually washed with water. The water-washing treatment can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of the water in the water washing treatment is usually about 5 to 40 ° C. In addition, the dipping time is usually about 1 to 120 seconds.

After washing with water, a drying process is performed to obtain a polarizing film. The drying process can be performed using a hot-air dryer or a far-infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C, and the time of the drying treatment is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By drying, the moisture content of the polarizing film can be reduced to a practical level. The moisture content is usually about 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and damage or breakage may occur after drying. When the moisture content exceeds 20% by weight, the thermal stability tends to be insufficient.

As described above, it is possible to manufacture a polarizing film in which a polyvinyl alcohol resin film adsorbs and aligns a dichroic pigment.

In addition, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the manufacturing steps of the polarizing film are examples. For example, it can be performed according to the method described in Japanese Patent Application Laid-Open No. 2012-159778. In the method described in this document, it is also useful to use a method in which a polyvinyl alcohol-based resin is formed by applying a polyvinyl alcohol-based resin to a base film to form a polarizing film.

In order to suppress the contraction force of the polarizing film to be low and to form the polarizing plate at a desired dimensional change rate, it is preferable to form the thickness of the polarizing film to 15 μm or less, and it may be formed to less than 15 μm. From the viewpoint of imparting good optical characteristics, the thickness of the polarizing film is usually 3 μm or more.

The thickness of the polarizing film 32 of the viewing-side polarizing plate is preferably larger than the thickness of the polarizing film 52 of the back-side polarizing plate. For example, the thickness of the polarizing film 32 included in the viewing-side polarizing plate is preferably 10 μm or more, and the thickness of the polarizing film included in the back-side polarizing plate is preferably less than 10 μm. The difference between the thicknesses of the polarizing film 32 and the polarizing film 52 is preferably 2 μm or more, 5 μm or more, and preferably less than 10 μm.

[Protective films 31a, 31b, 51]

The protective films 31a, 31b, and 51 can be made of an appropriate transparent resin. Specifically, it is preferable to use a polymer composed of a polymer having excellent transparency, uniform optical characteristics, mechanical strength, and thermal stability. Examples of the transparent resin film include cellulose resins such as cellulose triacetate and cellulose diacetate; polyethylene terephthalate, polyethylene isophthalate, and polybutylene terephthalate. Polyester-based resins; acrylic film such as poly (meth) acrylate and poly (meth) acrylate; polycarbonate-based A film, a polyether fluorene-based film, a polyfluorene-based film, a polyfluorene-based film, a polyolefin-based film, a polynorbornene-based film, and the like are not limited thereto.

The protective films 31 a and 31 b suitable for the viewing-side polarizing plate 30 and the protective film 51 suitable for the back-side polarizing plate 60 may be independently the same or different.

Before the protective film is bonded to the polarizing film, the bonding surface may be subjected to easy adhesion treatment such as saponification treatment, corona treatment, lead treatment, anchor coating treatment, and the like. The thickness of the protective film is usually in the range of 5 to 200 μm, preferably 10 μm or more, and more preferably 80 μm or less, and more preferably 40 μm or less.

In order to impart desired surface optical characteristics or other characteristics, a coating layer (surface treatment layer 35) may be provided on the outer surface of the protective film 31a. Specific examples of the coating layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. The method for forming the coating layer is not particularly limited, and a generally known method can be used.

In addition, as for the protective film 31a, a retardation plate for improving visibility when viewing a picture through polarized sunglasses may also be used. A λ / 4 plate as a retardation plate is preferred from the standpoint of improving the visibility. In addition, when a long polarizing film is laminated, when it is stretched at an angle of approximately 45 ° or 135 ° with respect to the long side direction of the long strip, a polarizing plate can be produced by a roll-to-roll method. Better.

When the liquid crystal cell is in the lateral electric field (IPS: In-Plane Switching) mode, in order not to damage the wide viewing angle characteristics of the IPS mode liquid crystal cell, the protective film 31b and the protective film 51 are arranged between the polarizing film and the liquid crystal cell. In this case, the retardation value R _th in the thickness direction is preferably in a range of -10 to 10 nm. Further, retardation value R _e is also located in the plane of the preferred range of 10 to 10nm.

The retardation value R _th in the thickness direction is a value obtained by multiplying the thickness of the film by a value obtained by subtracting the refractive index in the thickness direction from the average refractive index in the plane, and is defined by the following (a). Further, retardation value R _e in the plane of the film thickness by the refractive index difference value obtained above, and the following (b) defined above.

R _th = [(n _x + n _y ) / 2-n _z ] × d (a)

R _e = (n _x -n _y ) × d (b)

In the formula, n _x is the refractive index of the x-axis direction (slow-axis direction in the plane) in the film plane, and n _y is the y-axis direction (fast-axis direction in the plane) of the film plane, which is orthogonal to the x-axis in the plane. Direction), where n _z is the refractive index perpendicular to the z-axis direction (thickness direction) of the film surface, and d is the thickness of the film.

Here, the phase difference value may be an arbitrary wavelength within a range of about 500 to 650 nm near the center of visible light, but in this specification, a phase difference value of a wavelength of 590 nm is used as a standard. The retardation value R _{th in the} thickness direction and the in-plane retardation value R _e can be measured using various commercially available retarders.

The method of controlling the retardation value R _th in the thickness direction of the protective film to be within a range of -10 to 10 nm includes a method of reducing the strain remaining in the plane and the thickness direction as much as possible when the film is produced. For example, in the above-mentioned solvent casting method, a method of reducing the residual shrinkage strain in the plane and in the thickness direction generated when the cast resin solution is dried by heat treatment can be adopted. On the other hand, in the above-mentioned melt extrusion method, a resin film can be extruded from a die, and the distance from the die to the cooling drum can be shortened as much as possible in order to prevent stretching before cooling, At the same time, the method of controlling the amount of extrusion and the rotation speed of the cooling drum in such a way that the film is not stretched. In addition, as in the solvent casting method, a method of reducing the strain remaining in the obtained film by heat treatment may be adopted.

[Brightening film 61]

The back-side polarizing plate 60 of the present invention has a structure in which a brightness enhancement film 61 and an absorption-type polarizing plate 50 are laminated. A typical example of the brightness enhancement film 61 is a linearly polarized light separation type reflective polarizing film. Fig. 3 is a schematic cross-sectional view showing an example of a reflective polarizing film used in the present invention. The reflective polarizing film 61 is a multilayer laminate in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, in the example shown in the figure, the refractive index nx in the x-axis direction of layer A is greater than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of layer B is substantially the same as the refractive index ny in the y-axis direction . Therefore, the refractive index difference between the A layer and the B layer is large in the x-axis direction, and is substantially zero in the y-axis direction. As a result, the x-axis direction becomes the reflection axis, and the y-axis direction becomes the transmission axis. The refractive index difference in the x-axis direction between the A layer and the B layer is preferably 0.2 to 0.3. The x-axis direction corresponds to the stretching direction of the reflective polarizing film.

The A layer is preferably made of a material that exhibits birefringence by stretching. Typical examples of this material include naphthalenedicarboxylic acid polyesters (e.g., polyethylene naphthalate), polycarbonates, and acrylic resins (polymethyl Methyl acrylate). Polyethylene naphthalate is preferred. The B layer is preferably made of a material that does not substantially exhibit birefringence even when stretched. A representative example of this material is a copolyester of naphthalenedicarboxylic acid and terephthalic acid.

The reflective polarizing film transmits light having a first polarization direction (for example, p-wave) at the interface between the A layer and B layer, and allows light having a second polarization direction (for example, s-wave) to be orthogonal to the first polarization direction. )reflection. Part of the reflected light passes through the interface between the A layer and the B layer as light having a first polarization direction, and part of it is reflected as light having a second polarization direction. By repeating this reflection and penetration many times inside the reflective polarizing film, the light utilization efficiency can be improved.

Preferably, the reflective polarizing film 61 includes a reflective layer R as an outermost layer opposite to the polarizing film 52. By providing the reflective layer R, the light that is returned to the outermost part of the reflective polarizing film, which is ultimately unused, can be further used, so the light utilization efficiency can be further improved. The reflective layer R is typically one in which a reflective function is exhibited by a multilayer structure of a polyester resin layer.

The overall thickness of the reflective polarizing film can be appropriately set according to the purpose, the total number of layers included in the reflective polarizing film, and the like. From the viewpoint of suppressing dimensional change in a high-temperature environment, the entire thickness of the reflective polarizing film is preferably 15 μm to 50 μm, and particularly preferably 30 μm or less.

As the reflective polarizing film, for example, those described in Japanese Patent Application Publication No. 9-507308 can be used.

The reflective polarizing film 61 may be a commercially available product as it is, or a commercially available product may be processed twice (for example, stretched) and used. Commercially available products include, for example, the trade names DBEF and APF made by 3M Corporation.

[Lamination of polarizing film and protective film]

The polarizing film and the protective film can be bonded by an adhesive or an adhesive. The thickness of the adhesive layer for bonding the polarizing film and the protective film can be set to 0.01 to 30 μm, preferably 0.01 to 10 μm, and more preferably 0.05 to 5 μm. If the thickness of the adhesive layer is within this range, floating or peeling does not occur between the protective film and the polarizing film to be laminated, and a practically-adhesive force can be obtained. The thickness of the adhesive layer for bonding the polarizing film and the protective film can be set to 5 to 50 μm, preferably 5 to 30 μm, and more preferably 10 to 25 μm.

It is also useful to apply a saponification treatment, a corona treatment, or a plasma treatment to the polarizing film or the protective film in advance when the polarizing film and the protective film are attached.

In the formation of the adhesive layer, a suitable adhesive may be appropriately used in accordance with the type or purpose of the adherend, and an anchor coating agent may be used as necessary. Examples of the adhesive include solvent-based adhesives, emulsified adhesives, pressure-sensitive adhesives, re-wettable adhesives, polycondensation adhesives, solventless adhesives, film-shaped adhesives, and hot-melt adhesives. Wait.

One of the preferable adhesives includes a water-based adhesive, that is, a component in which the adhesive component is dissolved or dispersed in water, and examples of the water-soluble adhesive component include a polyvinyl alcohol-based resin. Examples of adhesive components dispersible in water are urethane resins having a hydrophilic group. The water-based adhesive agent can be prepared by mixing this adhesive agent component with additional additives prepared as needed in water. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives are listed below. KL-318, a carboxy-modified polyvinyl alcohol sold by Kuraray Co., Ltd.

The water-based adhesive contains a cross-linking agent as necessary. Examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, polyvalent metal salts, and the like. When a polyvinyl alcohol-based resin is used as an adhesive component, an aldehyde compound such as glyoxal, a methylol compound such as methylol melamine, and a water-soluble epoxy resin can be preferably used as the adhesive.联 剂。 Union agent. Here, the water-soluble epoxy resin can be, for example, polyamidoamine which reacts epichlorohydrin with a polyalkyl polyamine such as diethylenetriamine and triethylenetetramine and a dicarboxylic acid such as adipic acid Polyamine epoxy resin obtained by reacting polyamines. Commercial products of water-soluble epoxy resins include "Sumirez Resin (registered trademark) 650 (30)" sold by Taoka Chemical Industry Co., Ltd. and the like.

A polarizing film can be obtained by applying a water-based adhesive to the polarizing film and / or the bonding surface of the protective film bonded thereto, bonding the two, and then applying a drying treatment. Before the next step, it is also effective to apply a saponification treatment, a corona treatment, a plasma treatment, or a pull-up treatment to the protective film in advance to improve the wettability. The drying temperature can be set to, for example, about 50 to 100 ° C. After the drying treatment, curing at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ° C. for about 1 to 10 days, can further improve the adhesion, so it is preferred.

As another preferable adhesive, a curable adhesive composition containing an epoxy compound which is cured by irradiation or heating of active energy rays can be mentioned. Here, the hardenable epoxy compound has Those with less 2 epoxy groups. At this time, the polarizing film and the protective film may be adhered by irradiating the coating layer of the adhesive composition with active energy rays or applying heat to harden the curable epoxy compound contained in the adhesive. The hardening of an epoxy compound is generally performed by cationic polymerization of an epoxy compound. In addition, from the viewpoint of productivity, this hardening is preferably performed by irradiation with active energy rays.

From the viewpoints of weather resistance, refractive index, and cation polymerizability, the epoxy compound contained in the hardening adhesive composition is preferably one having no aromatic ring in the molecule. Examples of the epoxy compound having no aromatic ring in the molecule include hydrogenated epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. The epoxy compound used in such a hardenable adhesive composition can be preferably used. For example, the epoxy compound is described in detail in Japanese Patent Application Laid-Open No. 2004-245925, but it will be briefly described here.

The hydrogenated epoxy compound is, for example, a nuclear hydrogenation reaction of an aromatic polyhydroxy compound, which is a raw material of an aromatic epoxy compound, in a selective manner in the presence of a catalyst and under pressure, so that the obtained nuclear hydrogenated polyhydroxy compound Glycidyl etherified. Examples of the aromatic polyhydroxy compound as a raw material of the aromatic epoxy compound include bisphenols such as bisphenol A, bisphenol F, and bisphenol S; phenol-phenol resin, cresol-phenol resin, and hydroxybenzaldehyde Phenolic resins such as phenol-phenolic resins; polyhydroxy compounds such as tetrahydroxydiphenylmethane, tetrahydroxydiphenyl ketone, and polyvinylphenol. This aromatic polyhydroxy compound is subjected to a nuclear hydrogenation reaction, and epichlorohydrin is allowed to react with the obtained nuclear hydrogenated polyhydroxy compound, whereby glycidyl etherification can be performed. Preferred hydrogenated epoxy compounds include hydrogenated bisphenols Glycidyl ether of A.

An alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to an alicyclic ring" means a crosslinked oxygen atom -O- in a structure represented by the following formula, where m is an integer of 2 to 5.

A compound in which one or more hydrogen atoms in the form of (CH ₂ ) _m is subtracted from this formula and bonded to other chemical structures can become an alicyclic epoxy compound. In addition, one or more hydrogen atoms in (CH ₂ ) _m forming an alicyclic ring may be appropriately substituted by a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy compounds, an epoxy compound having an oxabicyclohexane ring (where m = 3 in the above formula) or an oxabicycloheptane ring (where m = 4 in the above formula) shows superiority. Because of its adhesiveness, it can be used better. The following series give specific examples of the alicyclic epoxy compound. Here, the names of the compounds are listed first, and then the corresponding chemical formulas are displayed, and the same symbols are given to the compound names and the corresponding chemical formulas.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy -6-methylcyclohexane carboxylate, C: ethylidene bis (3,4-epoxycyclohexane carboxylate), D: bis (3,4-epoxycyclohexylmethyl) adipate, E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: diethyl Glycol bis (3,4-epoxycyclohexylmethyl ether), G: ethylene glycol bis (3,4-epoxycyclohexylmethyl ether), H: 2,3,14,15-diepoxy -7,11,18,21-tetraoxatrihelix [5.2.2.5.2.2] docosane, I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy- 1,5-dioxaspiro [5.5] undecane, J: 4-vinylcyclohexene dioxide, K: limonene dioxide, L: bis (2,3-epoxycyclopentyl) ether, M : Dicyclopentadiene Dioxide, etc.

〔Chem 2〕

The aliphatic epoxy compound may be a polyglycidyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. Specific examples include diglycidyl ether of propylene glycol; diglycidyl ether of 1,4-butanediol; diglycidyl ether of 1,6-hexanediol Glycidyl ether; Triglycidyl ether of glycerol; Triglycidyl ether of trimethylolpropane; Addition of alkylene oxide (ethylene oxide or propylene oxide) to ethylene glycol, propylene glycol, and glycerol Polyglycidyl ethers of polyether polyols obtained from aliphatic polyols (eg, diglycidyl ether of polyethylene glycol) and the like.

In the curable adhesive composition, the epoxy compound may be used alone or in combination of two or more. Among these, the epoxy compound preferably contains an alicyclic epoxy compound having at least one epoxy group bonded to an alicyclic ring in the molecule.

The epoxy compound used for the curable adhesive composition usually has an epoxy equivalent in the range of 30 to 3,000 g / equivalent, and the epoxy equivalent is preferably in the range of 50 to 1,500 g / equivalent. When an epoxy compound having an epoxy equivalent of less than 30 g / equivalent is used, the flexibility of the polarizing plate after curing may be reduced, or the strength may be subsequently reduced. On the other hand, in a compound having an epoxy equivalent of more than 3,000 g / equivalent, the compatibility with other components contained in the adhesive composition may decrease.

From the viewpoint of reactivity, it is preferred that the curing reaction of the epoxy compound is performed by cationic polymerization. Therefore, it is preferable to prepare a cationic polymerization initiator in the curable adhesive composition containing an epoxy compound. Cationic polymerization initiators are produced by the irradiation or heating of visible light, ultraviolet rays, X-rays, and electron beam-like activation energy rays to generate cationic species or Lewis acids, and start the polymerization of epoxy groups. From the viewpoint of workability, it is preferred to impart latentity to the cationic polymerization initiator. The following is a cationic polymerization initiator that starts the polymerization of epoxy groups by generating a cationic species or a Lewis acid by irradiation with active energy rays. "Initiator" refers to a cationic polymerization initiator that generates a cationic species or a Lewis acid by heat and starts an epoxy group polymerization reaction, and is called a "thermal cationic polymerization initiator".

The method of using a photocationic polymerization initiator and hardening the adhesive composition by activating energy rays can be hardened at normal temperature and pressure, which can reduce the need to consider the heat resistance of the polarizing film or the distortion caused by expansion It is advantageous in that a protective film and a polarizing film can be adhered well. Moreover, since a photocationic polymerization initiator performs a catalyst action with light, even if it mixes with an epoxy compound, it is excellent in storage stability and workability | operativity.

Examples of the photocationic polymerization initiator include onium salts such as aromatic diazonium salts, aromatic sulfonium salts, and aromatic sulfonium salts; and iron-propadiene complexes. The blending amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and more preferably 15 parts by weight or less based on 100 parts by weight of the epoxy compound. When the blending amount of the photocationic polymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the epoxy compound, the curing is insufficient, and the mechanical strength or adhesive strength of the cured product tends to decrease. On the other hand, if the amount of the photocationic polymerization initiator is more than 20 parts by weight relative to 100 parts by weight of the epoxy compound, the ionic substance in the hardened substance increases, the hygroscopicity of the hardened substance is improved, and durability may be deteriorated. reduce.

When a photocationic polymerization initiator is used, the hardening adhesive composition may further contain a photosensitizer if necessary. By using a photosensitizer, the reactivity of cationic polymerization can be improved, and the mechanical strength or adhesion strength of the cured product can be improved. Examples of the photosensitizer include a carbonyl compound and an organic sulfur compound. Compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, photoreductive pigments, and the like. When the photosensitizer is blended, the amount is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the curable adhesive composition. In addition, in order to increase the hardening speed, a sensitizer such as a naphthoquinone derivative can be used.

On the other hand, examples of the thermal cationic polymerization initiator include benzyl sulfonium salt, Thiophenium, Thiolanium salt, benzyl ammonium, pyridine salt, hydrazine salt, carboxylic acid ester, sulfonic acid ester, Amine and imine.

The hardening adhesive composition containing an epoxy compound is preferably hardened by photocationic polymerization as described above, but the above-mentioned thermal cationic polymerization initiator may be present and hardened by thermal cationic polymerization, or Combined with photocationic polymerization and thermal cationic polymerization. When photocationic polymerization and thermal cationic polymerization are used in combination, it is preferred that the curable adhesive composition contains both a photocationic polymerization initiator and a thermal cationic polymerization initiator.

The curable adhesive composition may further contain a compound for promoting cationic polymerization, such as an oxo compound or a polyol compound. An oxo compound is a compound having a 4-membered cyclic ether in the molecule. When the oxyfluorene compound is prepared, the amount thereof is usually 5 to 95% by weight, preferably 5 to 50% by weight, in the curable adhesive composition. In addition, the polyol compound may be an alkanediol or an oligomer thereof containing ethylene glycol, hexamethylene glycol, polyethylene glycol, or the like, polyester polyol, polycaprolactone polyol, polycarbonate polyol Wait. When the polyol compound is prepared, the amount thereof is usually 50% by weight or less, and preferably 30% by weight or less in the curable adhesive composition.

In addition, as long as the hardening adhesive composition is not damaged, Adhesiveness may contain other additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, defoamers, and the like. Examples of the ion trapping agent include powdery inorganic compounds such as bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed systems thereof. Examples of the antioxidant include hindered phenol-based anti-oxidants. Oxidants, etc.

An epoxy compound-containing curable adhesive composition is applied to the adhesive surface of a polarizing film or a protective film or both of these adhesive surfaces, and then adhered to the surface after applying the adhesive, and irradiated with active energy rays Alternatively, the uncured adhesive layer can be hardened by heating, and a polarizing film and a protective film can be attached. The method for applying the adhesive may be, for example, a coating method such as a doctor blade, a wire rod, a die coating, a notch wheel coating, or a gravure coating.

This hardenable adhesive composition can basically be used as a solventless adhesive without substantially a solvent. However, since each coating method has its own optimum viscosity range, a solvent may be contained for viscosity adjustment. The solvent is preferably an organic solvent that does not reduce the optical characteristics of the polarizing film and can dissolve various components including epoxy compounds. For example, hydrocarbons such as toluene and esters such as ethyl acetate can be used. Wait.

When curing the adhesive composition by irradiation with active energy rays, various kinds of the foregoing can be used for the active energy rays. However, in terms of easy handling and easy control of the amount of irradiation light, ultraviolet rays can be preferably used. . The intensity or amount of radiation of active energy rays such as ultraviolet rays does not affect various optical properties such as the degree of polarization of the polarizing film and various optical properties such as the transparency or retardation characteristics of the protective film. Within the range, it can be appropriately determined to maintain moderate productivity.

When curing the adhesive composition by heat, heating can be performed by a generally known method. The heating is usually performed at a temperature above the temperature at which the cationic species or Lewis acid is generated by the thermal cationic polymerization initiator formulated in the hardenable adhesive composition, and the specific heating temperature is, for example, about 50 to 200 ° C.

[Adhesive]

As long as the adhesive is excellent in optical transparency and includes excellent adhesion properties including moderate wettability, cohesiveness, and adhesiveness, more preferably, it is also excellent in durability and the like. Specifically, as the adhesive for forming the adhesive layer, an adhesive containing an acrylic resin (acrylic adhesive) is preferred.

The acrylic resin contained in the acrylic adhesive is a resin whose main monomers are butyl acrylate, ethyl acrylate, isooctyl acrylate, and alkyl acrylate such as 2-ethylhexyl acrylate. In this acrylic resin, a polar monomer is usually copolymerized. A polar monomer is a compound having a polymerizable unsaturated bond and a polar functional group. Here, the polymerizable unsaturated bond is generally derived from a (meth) acrylfluorenyl group. In addition, the polar functional group may be a carboxyl group, a hydroxyl group, and a fluorenylamino group. , Amino, epoxy, etc. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, 2-N, N-dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, and the like.

In addition, in acrylic adhesives, Crosslinking agents are formulated together with the resin. Typical examples of the crosslinking agent include isocyanate compounds having at least two isocyanate groups (-NCO) in the molecule.

Various additives can be blended in the adhesive. Preferred additives include a silane coupling agent and an antistatic agent. Silane coupling agents are effective in improving adhesion to glass. Antistatic agents are effective in reducing or preventing the generation of static electricity.

The adhesive layer can be prepared by: preparing an adhesive composition in which the above adhesive component is dissolved in an organic solvent, directly coating this on a polarizing film or a protective film, and drying and removing the solvent; or The above-mentioned adhesive composition is coated on a release-treated surface of a base film composed of a resin film subjected to a release treatment, the solvent is dried and removed to form an adhesive layer, and this is adhered to a transparent protective film It is formed by a method of transferring an adhesive layer. When the adhesive layer is formed on the transparent protective film by the former direct coating method, the general method is to attach a resin film (also called a separation film) after the release treatment to the surface for temporary application. Protect the surface of the adhesive layer until use. From the viewpoint of handling properties of the adhesive composition as an organic solvent solution, the latter transfer method is often used. In this case, the base film after the release treatment for forming the adhesive layer is used first, After being attached to the polarizing plate, it can be directly used as a separation film, which is also preferable in this regard.

Before the adhesive is laminated on the polarizing film or the protective film, it is also useful to corona treat or plasma treat the polarizing film surface, the protective film surface, and the adhesive surface in advance.

[Adhesive layers 33, 53, adhesive layer 54]

The bonding of the polarizing plate and the liquid crystal cell, and the bonding of the absorption-type polarizing plate 50 and the brightness enhancement film 61 may use an adhesive or an adhesive, preferably an adhesive. As long as the adhesive layer is excellent in optical transparency and includes excellent adhesion properties such as moderate wettability, cohesiveness, and adhesiveness, it is more preferable that it is also excellent in durability and the like. Specifically, the adhesive that forms the adhesive layer is preferably an adhesive containing an acrylic resin (acrylic adhesive).

The adhesive layer may be the same as the user of the above-mentioned polarizing film and protective film, and the adhesive may be different or the same.

Before the adhesive is laminated on the polarizing plate, it is also useful to perform a corona treatment or a plasma treatment on the polarizing film surface, the protective film surface, and the adhesive surface in advance. In addition, when the brightness enhancement film is laminated, it is also useful to perform corona treatment or plasma treatment on the bonding surface and the adhesive surface of the brightness enhancement film 61 in advance. From the viewpoint of bringing the brightness enhancement film 61 closer to the liquid crystal cell, the adhesive layer used in the buildup of the brightness enhancement film is preferably 25 μm or less. It is more preferably 15 μm or less. The thickness of the adhesive layer is usually 3 μm or more.

The set of the polarizing plate of the present invention described above is preferably in the viewing-side polarizing plate 30, and the absorption axis of the polarizing film 32 is substantially parallel to the short-side direction of the liquid crystal cell, and in the back-side polarizing plate 60, polarized light The absorption axis of the film 52 is substantially parallel to the longitudinal direction of the liquid crystal cell.

[LCD cell]

A liquid crystal cell has two unit substrates and a substrate sandwiched between these substrates. Liquid crystal layer. The unit substrate is generally composed of glass, but it can also be a plastic substrate. In addition, the liquid crystal cell itself used in the liquid crystal panel of the present invention may be constituted by various persons employed in the field (for example, the driving mode is generally known as IPS mode, VA mode, TN mode, etc.).

[LCD panel]

The polarizing plate is bonded to the liquid crystal cell through the adhesive layer to make a liquid crystal panel.

The liquid crystal panel of the present invention is used: the distance from the liquid crystal cell to the brightness enhancement film is set to 100 μm or less, and the dimensional change rate in the direction of the absorption axis after the viewing-side polarizing plate is heated at 85 ° C. for 100 hours; A set of polarizing plates having a ratio of dimensional change in the absorption axis direction after heating the back side polarizing plate for 100 hours at a temperature of more than 1 and 1.4 or less. From another viewpoint, the absolute value of the warpage amount of the liquid crystal panel of the present invention after being heated at 85 ° C. for 240 hours is 0.5 mm or less, and preferably 0.3 mm or less. By attaching such a set of polarizing plates to a liquid crystal cell, the liquid crystal panel of the present invention can suppress warping in a high-temperature environment and become a liquid crystal display panel that can be accommodated in a frame of a final product.

The liquid crystal panel of the present invention is particularly preferably used as a liquid crystal display device for small and medium-sized applications that are exposed to high temperatures such as outdoors. For example, it is suitable when the size of the liquid crystal panel is 15 inches or less diagonally.

In addition, from the viewpoint of further reducing the warpage of the liquid crystal panel under a high temperature environment, the distance from the liquid crystal cell to the brightness enhancement film is preferably 80 μm or less, and more preferably 60 μm or less. In addition, will watch at 85 ° C The ratio of the dimensional change rate in the absorption axis direction after the side polarizer is heated for 100 hours, and the dimensional change rate in the absorption axis direction after the rear side polarizer is heated for 100 hours at 85 ° C. It is particularly preferably 1.05 or more and 1.3 or less.

The dimensional change rate in the absorption axis direction after the viewing-side polarizing plate is heated at 85 ° C. for 100 hours is preferably 1.0% or more, and more preferably 1.1% or more. In addition, the dimensional change rate in the absorption axis direction after the back-side polarizing plate is heated at 85 ° C. for 100 hours is preferably 1.1% or less, and more preferably 1.0% or less. The dimensional change rate in the direction of the absorption axis of the polarizing plate can be controlled, for example, by adjusting the length or temperature of the drying step after bonding the protective film to the polarizing film, the thickness of the polarizing film, and the stretching ratio of the polarizing film.

In addition, a method of adjusting the dimensional change rate in the absorption axis direction of the polarizing plate by performing a heat treatment in a range of 40 ° C. to 80 ° C. after making the polarizing plate is also useful. From the viewpoint of avoiding poor appearance due to rapid shrinkage of the polarizing plate, it is particularly preferable to perform heat treatment in a range of 40 ° C to 60 ° C.

The dimensional change rate in the absorption axis direction after the polarizing plate was heated at 85 ° C for 100 hours was measured in the following manner. First, the polarizing plate was cut into a size of 100 mm in the longitudinal direction and 100 mm in the width direction, and left to stand for one day in an environment of a temperature of 23 ° C. and a humidity of 55%, and the dimension (L ₀ ) in the MD direction (absorption axis direction) was measured. Then, it was left to stand in an environment of 85 ° C. for 100 hours, and the dimension (L ₁ ) in the MD direction after standing in a high-temperature environment was measured. Based on this result, the dimensional change rate is calculated from the formula (c).

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

The ratio of the dimensional change rate can be calculated from the value of the dimensional change rate A of the viewing-side polarizing plate and the dimensional change rate B of the back-side polarizing plate by the following formula (d).

Ratio of dimensional change rate = A / B (d)

[Example]

Hereinafter, the present invention will be described more specifically by showing examples, but the present invention is not limited to these examples. In the examples, parts and% indicating the content and the amount used are based on weight unless otherwise specified. The measurement of each physical property in the following examples was performed by the following method.

(1) Determination of thickness:

The measurement was performed using a Digital Micrometer "MH-15M" manufactured by Nikon Corporation.

(2) Measurement of in-plane retardation value and retardation value in thickness direction

A phase difference meter "KOBRA (registered trademark)-WPR" manufactured by Oji Measurement Co., Ltd. based on the principle of parallel polarization rotation method was used to measure the in-plane retardation value and thickness direction at a wavelength of 590 nm at a temperature of 23 ° C. Phase difference.

(3) Measurement of dimensional change rate

The measurement was performed using a two-dimensional measuring instrument "NEXIV VMR-12072" manufactured by Nikon Corporation.

(4) Measurement of the amount of warpage of the polarizing plate

The produced liquid crystal panel was left to stand at 85 ° C for 240 hours. Then, the viewing side polarizer was placed on the measurement table of a two-dimensional measuring instrument "NEXIV VMR-12072" made by Nikon Corporation with the upper side as the upper side. Next, focus on the surface of the measuring table and use this as a reference. Focus on the four corners of the LCD panel, the centers of the four sides, and the center of the LCD panel surface. , Set the longest distance between the absolute value and the measuring table as the warpage amount.

[Production Example 1] Production of Polarizing Film 1

Uniaxially stretch the polyvinyl alcohol film with a thickness of 20 μm (average degree of polymerization of about 2400, saponification degree of 99.9 mol or more) to about 4 times by dry stretching, and then maintain the tension state in pure water at 40 ° C. After immersing for 40 seconds, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.052 / 5.7 / 100 at 28 ° C for 30 seconds to perform a dyeing treatment. Then, it was immersed in an aqueous solution of a potassium iodide / boric acid / water weight ratio of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Next, it was washed with pure water at 8 ° C for 15 seconds, and was maintained at a tension of 300N, and then dried at 60 ° C for 50 seconds, followed by drying at 75 ° C for 20 seconds to obtain adsorption on a polyvinyl alcohol film. An absorption-type polarizing film with an orientation iodine thickness of 7 μm.

[Production Example 2] Production of Polarizing Film 2

Uniaxially stretch the polyvinyl alcohol film with a thickness of 30 μm (average degree of polymerization about 2400, saponification degree above 99.9 mol) to about 4 times by dry stretching, and then maintain the tension state, and immerse it in pure water at 40 ° C After 40 seconds, immerse in an aqueous solution of iodine / potassium iodide / water at a weight ratio of 0.052 / 5.7 / 100 at 28 ° C. 30 Seconds, and the dyeing process is performed. Then, it was immersed in an aqueous solution of a potassium iodide / boric acid / water weight ratio of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Then, it was washed with pure water at 8 ° C for 15 seconds, and was maintained at a tension of 300N, and then dried at 60 ° C for 50 seconds, and then dried at 75 ° C for 20 seconds to obtain an adsorption alignment on a polyvinyl alcohol film. Absorption type polarizing film with iodine thickness of 12 μm.

[Production Example 3] Production of water-based adhesive

3 parts by weight of carboxy-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd.] was dissolved in 100 parts by weight of water, and then 1.5 parts by weight of a water-soluble epoxy was added to its aqueous solution. Polyamine epoxy-based additive for resin [trade name "Sumirez Resin (registered trademark) 650 (30)" obtained from Taoka Chemical Industry Co., Ltd., 30% by weight aqueous solution of solid content] to prepare an aqueous system Agent.

[Adhesive A, B, C]

The following three adhesives were prepared.

Adhesive A: 20 μm-thick sheet adhesive [NCF #KT] by Lintec Corporation]

Adhesive B: 5 μm thick sheet adhesive [NCF # L2 by Lintec Corporation]

Adhesive C: 15 μm thick sheet adhesive [NCF # K1 by Lintec Corporation]

[Protective films A, B, C, D, E, F]

The following six kinds of protective films were prepared.

Protective film A: Konica Minolta Co., Ltd., cellulose triacetate film with hard coating; 25KCHCN-TC (thickness: 32μm)

Protective film B: Konica Minolta Co., Ltd. cellulose triacetate film; KC2CT (in-plane retardation value of thickness of 20 μm and wavelength of 590 nm = 1.2 nm, thickness direction retardation value of wavelength of 590 nm = 1.3 nm)

Protective film C: Cyclic polyolefin resin film made by Zeon Japan Co., Ltd .; ZF14-023 (in-plane retardation value at a thickness of 23 μm and a wavelength of 590 nm = 0.5 nm, and thickness direction retardation at a wavelength of 590 nm = 4.3 nm)

Protective film D: Cyclic polyolefin resin film made by Zeon Japan Co., Ltd .; ZF14-013 (in-plane retardation value of thickness 13 μm, wavelength 590 nm = 0.5 nm, thickness direction retardation value of wavelength 590 nm = 3.3 nm)

Protective film E: Konica Minolta Co., Ltd. cellulose triacetate film; KC2UAW (thickness: 25 μm)

Protective film F: Konica Minolta Co., Ltd. cellulose triacetate film; KC4UYW (40 μm thickness)

[Brightening film A]

The following brightness enhancement films were prepared.

Brightening film A: 26 μm thick brightening film (trade name "Advanced Polarized Film, Version 3" manufactured by 3M)

[Manufacturing example 4] Production of viewing-side polarizing plate 1

Protective film A is saponified, and one surface of protective film C is electrically charged. Halo processing. The protective film A, the polarizing film 2, and the protective film C are bonded with a water-based adhesive so that the triacetate surface of the protective film A and the corona-treated surface of the protective film C become bonding surfaces with the polarizing film 2, respectively. And subjected to a drying process to obtain a viewing-side polarizing plate 1.

The dimensional change rate in the MD direction of the viewing-side polarizing plate 1 was 1.02%. The dimensional change rate can be adjusted by adjusting the drying time in the drying process.

Furthermore, the adhesive agent A is adhered to the protective film C of the viewing-side polarizing plate 1 to form an adhesive agent layer. At this time, the surface of the protective film and the surface of the adhesive are corona-treated in advance.

[Manufacturing Examples 5 to 9] Production of Viewing Side Polarizers 2 to 6

The drying time in the above-mentioned drying process was adjusted so that the dimensional change rate in the MD direction (absorption axis direction) was different, and the viewing side polarizing plates 2 to 6 were produced in the same manner as in Production Example 4, and then the adhesive A was bonded. An adhesive layer is formed on the protective film C. The dimensional change rates of the viewing-side polarizing plates 2 to 6 are as follows.

Viewing side polarizer 2: 1.09

Viewing side polarizer 3: 1.23

Viewing side polarizer 4: 1.30

Viewing side polarizer 5: 1.41

Viewing side polarizer 6: 0.95

[Manufacturing example 10] Production of back-side polarizing plate 1

The protective film C is subjected to a corona treatment. The protective film C and the polarizing film 1 are bonded with a water-based adhesive so that the surface subjected to the corona treatment becomes a bonding surface with the polarizing film 1. Next, the adhesive B is bonded to the surface of the polarizing film 1 opposite to the surface to which the protective film C is bonded to form an adhesive layer. At this time, the surface of the polarizing film 1 and the surface of the adhesive B are corona-treated in advance. Then, the brightness enhancement film A is bonded to the surface of the adhesive B that is opposite to the surface to which the polarizing film 1 is bonded, and a back-side polarizing plate 1 is produced. At this time, the surface of the brightness enhancement film A is corona-treated in advance. The dimensional change rate of the back side polarizing plate 1 in the MD direction was 0.98%.

The adhesive agent A is adhered to the protective film C surface of the back side polarizing plate 1 thus obtained to form an adhesive agent layer. At this time, the surface of the protective film C and the surface of the adhesive A are also corona-treated in advance.

[Manufacturing example 11] Production of back-side polarizing plate 2

The protective film C is subjected to a corona treatment. The protective film C and the polarizing film 1 are bonded with a water-based adhesive so that the surface subjected to the corona treatment becomes a bonding surface with the polarizing film 1. Next, the adhesive B is bonded to the surface of the protective film C opposite to the surface to which the polarizing film 1 is bonded to form an adhesive layer. At this time, the surface of the protective film C and the surface of the adhesive B are corona-treated in advance. Then, the brightness enhancement film A is bonded to the surface of the adhesive B that is opposite to the surface to which the protective film C is bonded, and the back-side polarizing plate 2 is produced. At this time, the surface of the brightness enhancement film A is corona-treated in advance. The dimensional change rate of the back side polarizing plate 2 in the MD direction was 0.98%.

Adhesive A is bonded to the polarization of the back-side polarizing plate 2 thus obtained. One side of the light film forms an adhesive layer. At this time, the surface of the polarizing film 1 and the surface of the adhesive A are also corona-treated in advance.

[Manufacturing example 12] Production of back-side polarizing plate 3

The protective film D is corona-treated. The protective film D and the polarizing film 1 are bonded with a water-based adhesive so that the surface subjected to the corona treatment becomes a bonding surface with the polarizing film 1. Next, the adhesive B is bonded to the surface of the protective film D opposite to the surface on which the polarizing film 1 is bonded to form an adhesive layer. At this time, the surface of the protective film D and the surface of the adhesive B are corona-treated in advance. Then, the protective film E after being subjected to the saponification treatment is bonded to the surface of the adhesive B opposite to the surface on which the protective film D is bonded. Furthermore, the adhesive C is adhered to the surface of the protective film E opposite to the surface to which the adhesive B is adhered, to form an adhesive layer. At this time, the surface of the adhesive C is corona-treated in advance. Finally, the brightness enhancement film A is bonded to the surface of the adhesive C opposite to the surface to which the protective film E is bonded, and the back-side polarizing plate 3 is produced. At this time, the surface of the brightness enhancement film A is corona-treated in advance. The dimensional change rate of the back side polarizing plate 3 in the MD direction was 0.97%.

The adhesive agent A was adhered to the polarizing film 1 surface of the back side polarizing plate 3 thus obtained to form an adhesive agent layer. At this time, the surface of the polarizing film 1 and the surface of the adhesive A are also corona-treated in advance.

[Manufacturing example 13] Production of back-side polarizing plate 4

The protective film D is corona-treated. The protective film is bonded with a water-based adhesive so that the corona-treated surface becomes a bonding surface with the polarizing film 1 D 与 Polarizing film 1. Next, the adhesive B is adhered to the surface of the protective film D opposite to the surface to which the polarizing film 1 is attached to form an adhesive layer. At this time, the surface of the protective film D and the surface of the adhesive B are corona-treated in advance. Then, the protective film F after being subjected to the saponification treatment is bonded to the surface of the adhesive B opposite to the surface to which the protective film D is bonded. In addition, the adhesive B is bonded to the protective film F, and the surface on which the adhesive B is bonded is the surface opposite to the surface to form an adhesive layer. At this time, the surface of the adhesive B is corona-treated in advance. Finally, the brightness enhancement film A is bonded to the surface of the adhesive B that is opposite to the surface to which the protective film F is bonded, and the back-side polarizing plate 4 is produced. At this time, the surface of the brightness enhancement film A is corona-treated in advance. The dimensional change rate of the back side polarizing plate 4 in the MD direction was 0.75%.

The adhesive agent A is adhered to the polarizing film 1 surface of the back-side polarizing plate 4 thus obtained to form an adhesive agent layer. At this time, the surface of the polarizing film 1 and the surface of the adhesive A are also corona-treated in advance.

[Manufacturing example 14] Production of back-side polarizing plate 5

The protective film D is corona-treated. The protective film D and the polarizing film 1 are bonded with a water-based adhesive so that the surface subjected to the corona treatment becomes a bonding surface with the polarizing film 1. Next, the adhesive B is adhered to the surface of the protective film D opposite to the surface to which the polarizing film 1 is attached to form an adhesive layer. At this time, the surface of the protective film D and the surface of the adhesive B are corona-treated in advance. Then, the protective film F after being subjected to the saponification treatment is bonded to the surface of the adhesive B opposite to the surface to which the protective film D is bonded. Furthermore, the surface where the adhesive A is adhered to the protective film F and the surface where the adhesive B is adhered are opposite sides, and Form an adhesive layer. At this time, the surface of the adhesive A is corona-treated in advance. Finally, the brightness enhancement film A is bonded to the surface of the adhesive A opposite to the surface to which the protective film F is bonded, and a back-side polarizing plate 5 is produced. At this time, the surface of the brightness enhancement film A is corona-treated in advance. The dimensional change rate of the back side polarizing plate 5 in the MD direction was 0.58%.

The adhesive agent A is adhered to the polarizing film 1 surface of the back side polarizing plate 5 thus obtained to form an adhesive agent layer. At this time, the surface of the polarizing film 1 and the surface of the adhesive A are also corona-treated in advance.

[LCD cell]

From the liquid crystal panel of Nexus 7 manufactured by Google Inc., the viewing-side polarizing plate and the back-side polarizing plate were separated to obtain a liquid crystal cell.

[Example 1]

The viewing-side polarizing plate 1 is cut to a size of 7 inches diagonally so that the absorption axis of the polarizing film is parallel to the short side of the liquid crystal cell, and the absorption axis of the polarizing film is relative to the length of the liquid crystal cell. The sides are parallel, and the back side polarizing plate 1 is cut to a size of 7 inches diagonally. The thus-produced polarizing plate was adhered to a liquid crystal cell through an adhesive to produce a liquid crystal panel. The ratio of the dimensional change rate of the viewing-side polarizing plate to the back-side polarizing plate was 1.04. The distance from the brightness enhancement film to the liquid crystal cell was 55 μm.

The thus-produced liquid crystal panel was left to stand in an environment of 85 ° C. for 240 hours, and the amount of warpage was measured. As a result, it was 0.4 mm.

[Examples 2 to 10, Comparative Examples 1 to 5]

A liquid crystal panel was produced in the same manner as in Example 1 except that the viewing-side polarizing plate and the back-side polarizing plate shown in Table 1 were used.

Dimensional change rate in the absorption axis direction of the viewing-side polarizers used in Examples 1 to 10 and Comparative Examples 1 to 5 The distance from the film to the liquid crystal cell and the ratio of the dimensional change are shown in Table 1 as a whole.

[Industrial applicability]

According to the present invention, warping of a liquid crystal panel in a high-temperature environment can be solved, and a liquid crystal panel that can be accommodated in a frame of a final product even in a high-temperature environment can be obtained.

Claims (5)

A set of polarizing plates is a set of viewing-side polarizing plates arranged on the viewing side of a liquid crystal cell and a set of back-side polarizing plates arranged on the back side of the liquid crystal cell. The structure of the film and the absorptive polarizer is disposed on the back side of the liquid crystal cell, the distance from the surface in contact with the liquid crystal cell to the brightness enhancement film is 60 μm or less, and the viewing side polarizer is heated at 85 ° C. for 100 hours The ratio of the dimensional change rate in the subsequent absorption axis direction and the dimensional change rate in the absorption axis direction after heating the back side polarizing plate at 85 ° C. for 100 hours exceeds 1 and is 1.4 or less. The size of the back side polarizing plate The rate of change is 0.98% or less. The set of polarizing plates according to item 1 of the scope of patent application, wherein the viewing-side polarizing plate and the back-side polarizing plate each have a polarizing film, and the viewing-side polarizing plate has a thickness greater than that of the back surface. The side polarizing plate has a thickness of a polarizing film. The set of polarizing plates according to item 1 or 2 of the scope of patent application, wherein the absorptive polarizing plate included in the back side polarizing plate has a polarizing film, and the absorptive polarizing plate is only one side of the polarizing film A polarizing plate with a protective film. A liquid crystal panel comprising a set of polarizing plates according to any one of claims 1 to 3 and a liquid crystal cell, wherein the viewing-side polarizing plate has an absorption axis and a short-side direction of the liquid crystal cell. It is substantially parallel, and the absorption axis of the back side polarizing plate is substantially parallel to the longitudinal direction of the liquid crystal cell. A liquid crystal panel is a liquid crystal panel described in item 4 of the scope of patent application, or a liquid crystal panel including a liquid crystal cell and a set of polarizing plates described in any one of the scope of patent applications 1 to 3. The viewing-side polarizing plate is arranged on the viewing side of the unit, and the rear-side polarizing plate is arranged on the back side of the liquid crystal cell. The absolute value of the amount of warpage after heating at 85 ° C for 240 hours is 0.5 mm or less.