TWI605286B - Set of polarizing plates and liquid crystal display panel - Google Patents

Description

Polarizer set and LCD panel

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

In recent years, liquid crystal displays that consume low power, operate at low voltage, and are lightweight and thin have been rapidly popularized as display devices for information such as mobile phones, portable information terminals, monitors for computers, and televisions. With the development of liquid crystal technology, various modes of liquid crystal displays have been proposed, which continuously solve problems of liquid crystal displays such as response speed, contrast, and narrow viewing angle. Moreover, with the popularity of liquid crystal displays for mobile phones, liquid crystal panels are also required to be thin and light.

With the reduction in thickness of the liquid crystal panel, the liquid crystal panel warps due to shrinkage of the polarizing plate bonded to the liquid crystal cell in a high-temperature environment, and there is a problem that it cannot be accommodated in the casing of the final product.

In order to suppress the warpage of such a liquid crystal display panel, it has been previously developed to suppress the liquid crystal display 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. The means of warping the panel. For example, Japanese Laid-Open Patent Publication No. 2012-58429 (Patent Document 1) discloses that the viewing side is disposed on the viewing side of the liquid crystal cell. The thickness of the polarizing film (the polarizing film in the present invention) is thinner than that of the polarizing film disposed on the back side of the liquid crystal cell, and the method of suppressing warpage of the liquid crystal display panel.

Further, Japanese Laid-Open Patent Publication No. 2013-37115 (Patent Document 2) discloses a polarizing film (a polarizing film in the present invention) included in an optical layered body on the viewing side, which is disposed opposite to the viewing side. The polarizing film contained in the optical laminate of the side is thicker than 5 μm, and means for suppressing warpage of the liquid crystal panel. However, for the suppression of the warpage of the liquid crystal panel, the space for improvement is still large.

[Previous Technical Literature] [Patent Literature]

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

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

An object of the present invention is to provide a liquid crystal panel in which a polarizing plate capable of suppressing warpage of a liquid crystal panel in a high-temperature environment and a set of the polarizing plate are bonded to a liquid crystal cell.

[1] A set of polarizing plates, which is disposed on a viewing side polarizing plate on a viewing side of a liquid crystal cell, and a set of a back side polarizing plate disposed on a back side of the liquid crystal cell, wherein the back side polarizing plate has When the brightness enhancement film and the absorption type polarizing plate are laminated, when they are disposed on the back side of the liquid crystal cell, the connection is made The distance between the surface of the liquid crystal cell and the brightness enhancement film is 100 μm or less, and the dimensional change rate in the absorption axis direction when the viewing-side polarizing plate is heated at 85° C. for 100 hours and the content of the back surface-side polarizing plate The ratio of the dimensional change ratio in the absorption axis direction when the absorptive polarizing plate was heated at 85 ° C for 100 hours was 0.62 or more and 1.25 or less.

[2] The polarizing plate set according to the above aspect, wherein the viewing-side polarizing plate and the back-side polarizing plate each have a polarizing film, and a thickness of the polarizing film of the viewing-side polarizing plate and the back surface side The polarizing film has a polarizing film having a thickness of 15 μm or less.

[3] The polarizing plate kit according to [1], wherein the viewing-side polarizing plate has an absorption axis that is approximately parallel to a longitudinal direction of the liquid crystal cell, and the back-side polarizing plate is an absorption axis thereof. It is approximately parallel to the short-side direction of the liquid crystal cell.

[4] The liquid crystal panel of the polarizing plate according to the above [1], wherein the viewing-side polarizing plate is disposed on a viewing side of the liquid crystal cell, and the back side polarizing plate is disposed on the front side. On the back side of the liquid crystal cell, the absolute value of the warpage amount of the liquid crystal panel when heated at 85 ° C for 240 hours was 0.5 mm or less.

According to the present invention, it is possible to obtain a liquid crystal panel which can eliminate the warpage of the liquid crystal panel in a high temperature environment and which can be accommodated in the casing of the final product even in a high temperature environment.

30‧‧‧ viewing side polarizer

31a, 31b, 51a, 51b‧‧‧ protective film

32, 52‧‧‧ polarizing film

35‧‧‧Surface treatment layer

33, 53‧‧‧Adhesive layer

50‧‧‧Absorbing polarizer

54‧‧‧Next layer

60‧‧‧Back side polarizer

61‧‧‧Brightening film

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

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

Fig. 3 is a schematic cross-sectional view showing an example of a preferred layer constitution of a set of polarizing plates of the present invention.

Fig. 4 is a view showing an example of a reflective polarizing film used in the present invention.

Hereinafter, the kit of the polarizing plate of the present invention and the liquid crystal panel using the same will be described using a suitable drawing, but the present invention is not limited to the embodiments.

The kit of polarizing plates of the present invention is composed of a viewing-side polarizing plate 30 and a back-side polarizing plate 60.

The layer configuration of the viewing-side polarizing plate 30 and the back-side polarizing plate 60 of the present invention will be described with reference to Fig. 1 . In the first embodiment, the viewing-side polarizing plate 30 is bonded to the protective film 31a and 31b on both surfaces of the polarizing film 32. The surface on which the protective film 31a and the polarizing film 32 are bonded to each other may be the opposite side, and a surface-treated layer may be used. In the present invention, the absorptive polarizing plate 50 has a protective film on at least one surface of the polarizing film 52. As shown in FIG. 1, the protective film 51a may be bonded to both surfaces of the polarizing film 52, Formed by 51b. Further, the brightness enhancement film 61 is laminated on the absorption type polarizing plate 50 via the adhesive layer 54 to form the back side polarizing plate 60. The polarizing plates are bonded to the liquid crystal cells via the adhesive layers 33 and 53, respectively, to form a liquid crystal panel.

In the foregoing back side polarizing plate, from the liquid crystal cell to brightening The distance of the film 61 is 100 μm or less, preferably 90 μm or less, more preferably 80 μm or less, or 60 μm or less. The lower limit is not particularly limited, but is usually 5 μm or more, and more typically 10 μm or more. In addition, the dimensional change rate in the absorption axis direction when the viewing-side polarizing plate 30 is heated at 85 ° C for 100 hours, and the absorption axis when the absorption-type polarizing plate 50 included in the back-side polarizing plate is heated at 85 ° C for 100 hours The ratio of the dimensional change ratio of the direction is 0.62 or more and 1.25 or less, preferably 0.65 or more and 1.2 or less, more preferably 0.75 or more and 1.15 or less. In the present invention, the distance from the liquid crystal cell to the brightness enhancement film means a surface which is in contact with the liquid crystal cell from the back side polarizing plate (for example, as shown in Figs. 1 to 3, which corresponds to an adhesive layer). The distance from the surface of the liquid crystal cell of 53 to the surface of the liquid crystal cell side of the brightness enhancement film.

The amount of warpage of the liquid crystal panel is largely affected by the brightness enhancement film disposed on the outermost layer of the liquid crystal cell. Therefore, the distance between the liquid crystal panel and the brightness enhancement film satisfies the above, and the dimensional change in the absorption axis direction when the absorption-type polarizing plate 50 included in the viewing-side polarizing plate 30 and the back-side polarizing plate is heated at 85 ° C for 100 hours. The rate is as described above, and the amount of warpage of the liquid crystal panel can be reduced.

As shown in the second and third embodiments, 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 has a protective film only on one side of the polarizing film. It is also a preferred composition. Thus, by arranging the brightness enhancement film at a position closer to the liquid crystal cell, the influence of the force generated by the change in the size of the brightness enhancement film on the warpage of the liquid crystal panel can be reduced.

Further, in the viewing-side polarizing plate, the absorption axis is approximately parallel to the longitudinal direction of the liquid crystal cell, and the back side polarizing plate is taken The arrangement in which the absorption axis is approximately parallel to the short side direction of the liquid crystal cell is preferable. The term "parallel parallel" is not limited to being strictly parallel. For example, the angle formed by the absorption axis of the polarizing plate and the sides of the liquid crystal cell is preferably 5 or less, more preferably 3 or less, and still more preferably 1 or less. When such a shaft is used, the warpage of the liquid crystal panel can be more significantly reduced.

Further, according to the present invention, it is also possible to provide the liquid crystal panel in which the viewing-side polarizing plate 30 and the back-side polarizing plate 60 are laminated on the liquid crystal cell via the adhesive layer.

Hereinafter, the members constituting the kit of the polarizing plate of the present invention and the liquid crystal panel will be described in detail. In addition, the polarizing film 32 of the viewing-side polarizing plate and the polarizing film 52 of the back-side polarizing plate are collectively referred to as a polarizing film, and are collectively referred to as a protective film 31a, a protective film 31b, a protective film 51a, and a protective film 51b. Just called a protective film.

[Polarizing film 32, 52]

As the polarizing films 32 and 52, any suitable size may be used as long as the dimensional change ratio and the thickness of the polarizing film are satisfied. The polarizing film is usually produced by a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of dyeing a polyvinyl alcohol-based resin film by a dichroic dye to adsorb a dichroic dye, and adsorbing two colors. The step of treating the polyvinyl alcohol-based resin film of the dye with a boric acid aqueous solution and the step of washing with water by a cross-linking treatment with an aqueous boric acid solution.

The polyvinyl alcohol-based resin can be produced by saponification of a polyvinyl acetate-based resin. The polyvinyl acetate resin may be vinyl acetate and may be co-polymerized in addition to the polyvinyl acetate of the homopolymer of vinyl acetate. A copolymer of other monomers polymerized. Examples of the other monomer copolymerizable with vinyl acetate include an unsaturated carboxylic acid, an olefin, a vinyl ether, an unsaturated sulfonic acid, and an acrylamide having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually from about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin can be modified. For example, polyvinyl formal or acetal modified with an aldehyde can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, preferably from about 1,500 to 5,000.

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

The longitudinal uniaxial stretching of the polyvinyl alcohol-based resin film can be carried out before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. The longitudinal uniaxial stretching is carried out after dyeing, which can be carried out before the boric acid treatment or in the boric acid treatment. Of course, longitudinal uniaxial stretching can also be performed at the complex stages shown here. The longitudinal uniaxial extension system may be a method of uniaxially extending between rollers having different rotational speeds, or a method of uniaxially extending using a hot roller. In addition, the longitudinal uniaxial stretching may be carried out by dry stretching in the air, or may be carried out by using a solvent such as water to extend the wet stretching of the polyvinyl alcohol resin film in a state of being expanded. The stretching ratio is usually about 3 to 8 times.

Polyvinyl alcohol resin film dyed with dichroic dye The treatment can be carried out, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. Further, the polyvinyl alcohol-based resin film is preferably subjected to a treatment of immersing in water and expanding it before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide is usually used for dyeing.

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. Further, the immersion time (dyeing time) of 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 of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is generally employed. 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 aqueous solution may also 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. Moreover, the immersion time (dyeing time) of the aqueous solution is usually 10 to 1,800 seconds.

The boric acid treatment after dyeing of the dichroic dye can be carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The content of boric acid in an aqueous solution containing boric acid, per 100 water The parts by weight are usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight. In the case where iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid is usually from about 0.1 to 15 parts by weight, preferably from 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time for the aqueous solution containing boric acid is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment is carried out, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. The temperature of the water treated with water is usually about 5 to 40 °C. Moreover, the immersion time is usually about 1 to 120 seconds.

After washing with water, it was dried to obtain a polarizing film. The drying treatment can be carried out 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. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the proportion of water in the polarizing film is reduced to practical use. The moisture ratio is usually from 5 to 20% by weight, preferably from 8 to 15% by weight. When the moisture ratio is less than 5% by weight, the polarizing film loses flexibility, and the polarizing film may be damaged or broken after drying. Further, when the water content is more than 20% by weight, the thermal stability of the polarizing film tends to be insufficient.

As described above, a polarizing film in which a dichroic dye is adsorbed and oriented to a polyvinyl alcohol-based resin film can be produced.

Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol-based resin film in the production step of the polarizing film can be carried out, for example, according to the method described in JP-A-2012-159778. In the method described in this document, a method of forming a polyvinyl alcohol-based resin layer to be a polarizing film by applying a polyvinyl alcohol-based resin to a base film can also be used.

In order to suppress the contraction force of the polarizing film to be low, the polarizing plate has a desired dimensional change ratio, and the thickness of the polarizing film is preferably 15 μm or less, and may be less than 15 μm. The thickness of the polarizing film is usually 3 μm or more at a point where good optical characteristics can be imparted.

[Protective film 31a, 31b, 51a, 51b]

As the protective films 31a, 31b, 51a, and 51b, those formed of a suitable transparent resin can be used. Specifically, it is preferred to use a polymer which is excellent in transparency, uniform optical characteristics, mechanical strength, thermal stability, and the like. As such a transparent resin film, for example, a cellulose film such as triethyl fluorenyl cellulose or diethyl fluorenyl cellulose, polyethylene terephthalate, polyethylene isophthalate, and a poly pair can be used. A polyester film such as butyl phthalate, an acrylic film such as poly(methyl) acrylate or poly(methyl) acrylate, a polycarbonate film, a polyether fluorene film, or a polyfluorene A film, a polyimide film, a polyolefin film, a polynormene film, etc. are not limited to these.

The protective films 31a and 31b which are applied to the viewing-side polarizing plate 30 and the protective films 51a and 51b which are applied to the back-side polarizing plate 60 may be independently the same or different.

The protective film may be subjected to saponification treatment, corona treatment, primer treatment, anchor coating on the bonding surface before bonding the polarizing film. Easy processing of cloth processing, etc. The thickness of the protective film is usually in the range of about 5 to 200 μm, preferably 10 μm or more, more preferably 80 μm or less, still more preferably 40 μm or less.

Moreover, 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, a charge prevention layer, and an antifouling layer. The method of forming the coating layer is not particularly limited, and a conventional method can be used.

Further, a phase difference plate for improving the visibility when the screen is seen through the polarized sunglasses may be used for the protective film 31a. From the viewpoint of improving the visibility, it is desirable to configure a λ/4 wavelength plate as a phase difference plate. Further, when laminating with the polarizing film on the long strip, when the angle formed by the longitudinal direction of the strip is extended to about 45 or 135, the polarizing plate can be formed by the roller to the roller, which is preferable.

In the case where the liquid crystal cell is in the IPS (In-Plane Switching) mode, the phase difference Rth of the protective film 31b and the protective film 51b in the thickness direction is - in order not to impair the wide viewing angle characteristics of the IPS mode liquid crystal cell. A range of 10 to 10 nm is preferred. Further, the in-plane phase difference Re is also preferably in the range of -10 to 10 nm.

The phase difference value Rth in the thickness direction is a value obtained by multiplying the value of the refractive index in the thickness direction from the average refractive index in the plane by the thickness of the film, and is defined by the following formula (a). Further, the in-plane phase difference value Re, the value of the refractive index difference in the plane multiplied by the thickness of the film, is defined by the following formula (b).

Rth=[(nx+ny)/2-nz]×d (a)

Re=(nx-ny)×d (b)

In the formula, nx is a refractive index in the x-axis direction (in-plane retardation axis direction) in the film plane, and ny is a y-axis direction in the film plane (in-plane forward axis direction, in the plane perpendicular to the x-axis) The refractive index, nz is the refractive index of the vertical film surface in the z-axis direction (thickness direction), and d is the thickness of the film.

Here, the phase difference value may be a value of an arbitrary wavelength in the range of about 500 to 650 nm in the vicinity of the center of visible light, and the phase difference of the wavelength of 590 nm is used as a standard in the specification. The phase difference value Rth in the thickness direction and the phase difference value Re in the plane can be measured using various commercially available phase difference meters.

As a method of controlling the phase difference Rth in the thickness direction of the protective film in the range of -10 to 10 nm, for example, a method of reducing the distortion remaining in the in-plane and thickness directions as much as possible is employed. For example, in the solvent casting film method, a method of relaxing the residual shrinkage in the in-plane and thickness directions which occurs when the resin solution is dried is used, and the method is moderated by heat treatment. On the other hand, in the above melt extrusion method, in order to prevent the elongation of the resin film from the extrusion of the die to the cooling, it is possible to minimize the distance from the die to the cooling drum while controlling the amount of extrusion and The method of cooling the rotation speed of the drum so as not to be stretched. Further, in the same manner as the solvent casting method, a method of relaxing the distortion of the obtained film by heat treatment may be employed.

[Brightness film 61]

The back side polarizing plate 60 of the present invention has a brightness enhancement film 61 and absorption The polarizing plate 50 is formed by lamination. As the brightness enhancement film 61, for example, a linear polarization separation type reflective polarizing film can be exemplified. Fig. 4 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 laminated body in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. For example, in the illustrated example, the refractive index nx in the x-axis direction of the layer A is larger than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of the layer B and the refractive index ny in the y-axis direction are substantially the same. Therefore, the refractive index difference between the A layer and the B layer is large in the x-axis direction and 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 between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3. Furthermore, the x-axis direction corresponds to the direction in which the reflective polarizing film extends.

The layer A is preferably made of a material which exhibits birefringence by stretching. Typical examples of such a material include a naphthalene dicarboxylic acid polyester (for example, polyethylene naphthalate), a polycarbonate, and an acrylic resin (for example, methyl methacrylate). Polyethylene naphthalate is preferred. It is preferable that the above-mentioned layer B is formed of a material which does not exhibit birefringence substantially even if it extends. As a representative example of such a material, for example, a copolyester of naphthalene dicarboxylic acid and terephthalic acid.

The reflective polarizing film is connected to the interface between the A layer and the B layer, and transmits light having a first polarization direction (for example, a p-wave), and reflects light having a second polarization direction perpendicular to the first polarization direction (for example, an s-wave). The reflected light is at the interface between the A layer and the B layer, and a part of the light is transmitted by the light having the first polarization direction, and a part of the light is reflected by the light having the second polarization direction. In the interior of the reflective polarizing film, such reversal is repeated by most Shooting and transmitting can improve the efficiency of light utilization.

It is preferable that the reflective polarizing film 61 includes the reflective layer R as the outermost layer opposite to the polarizing film 52. By providing the reflective layer R, the most external light that is not used and returned to the reflective polarizing film can be reused, so that the light use efficiency can be further improved. The reflective layer R is representatively exhibiting a reflection function by a multilayer structure of a polyester resin layer.

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

As the reflective polarizing film, for example, those described in JP-A-9-507308 can be used.

As the reflective polarizing film 61, a commercially available product can be used as it is, or a commercially available product can be used as a secondary processing (for example, stretching). As a commercial item, the brand name DBEF and APF by 3M company are mentioned, for example.

[Adhesion of polarizing film and protective film]

The bonding of the polarizing film and the protective film can be carried out by an adhesive or an adhesive. The adhesive layer for bonding the polarizing film and the protective film may have a thickness of about 0.01 to 30 μm, preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm. When the thickness of the coating layer is within this range, floating and peeling do not occur between the laminated protective film and the polarizing film, and an adhesive force which is practically problem-free can be obtained. The adhesive layer to which the polarizing film and the protective film are attached may have a thickness of about 5 to 50 μm, preferably 5 to 30 μm, more preferably 10 to 25 μm.

When the polarizing film and the protective film are next to each other, the polarizing film or the protective film may be subjected to saponification treatment, corona treatment, plasma treatment, or the like in advance.

In the formation of the adhesive, an appropriate and appropriate adhesive can be used depending on the type and purpose of the adherend, and an anchor coating agent can also be used as needed. The adhesive agent may, for example, be a solvent-based adhesive, an emulsified adhesive, a pressure-sensitive adhesive, a rewet adhesive, a polycondensation adhesive, a solventless adhesive, a film adhesive, or a hot melt type. Agents, etc.

As one of the preferable adhesives, for example, a water-based adhesive, that is, an adhesive component is dissolved or dispersed in water. When an example of an adhesive component which can be dissolved in water is mentioned, there is a polyvinyl alcohol-based resin. Further, in the case of an example of an adhesive component which can be dispersed in water, there is an amine ester-based resin having a hydrophilic group. The water-based adhesive can be prepared by mixing such an adhesive component with an additional additive as needed, and mixing with water. When an example of a commercially available polyvinyl alcohol-based resin which can be a water-based adhesive is used, there is a "KL-318" of a carboxyl-modified polyvinyl alcohol sold by Kuraray.

The aqueous binder may contain a crosslinking agent as needed. Examples of the crosslinking agent include an amine compound, an aldehyde compound, a methylol compound, a water-soluble epoxy resin, an isocyanate compound, a polyvalent metal salt, and the like. When a polyvinyl alcohol-based resin is used as the adhesive component, a hydroxy compound represented by glyoxal, a methylol compound typified by methylol melamine, a water-soluble epoxy resin or the like is preferably used as the crosslinking agent.

Here, the water-soluble epoxy resin is, for example, a polyamine polyamine which is a reaction product of a polyalkylene polyamine such as di-ethyltriamine or tri-ethyltetramine and a dicarboxylic acid such as adipic acid. A polyamide resin obtained by reacting epichlorohydrin. In the case of a commercially available product of a water-soluble epoxy resin, "SUMIREZ RESIN (registered trademark) 650 (30)", which is sold by the company, is available from the company.

A water-based adhesive is applied to the surface of the polarizing film and/or the protective film bonded thereto, and after bonding the two, a polarizing plate can be obtained by performing a drying treatment. Next, the protective film is subjected to an easy-to-treat treatment such as a saponification treatment, a corona discharge treatment, a plasma treatment, or a primer treatment, and it is also effective to improve the wettability in advance. The drying temperature may be, for example, about 50 to 100 °C. After the drying treatment, it is preferably aged 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, and it is preferable to further increase the adhesion.

Another preferable adhesive agent is, for example, a curable adhesive composition containing an epoxy compound which is cured by irradiation or heating of an active energy ray. Here, the curable epoxy compound has at least two epoxy groups in the molecule. At this time, the adhesion between the polarizing film and the protective film is performed by irradiating the coating layer of the adhesive composition with an active energy ray or applying heat to cure the curable epoxy compound contained in the adhesive. The hardening of the epoxy compound is generally carried out by cationic polymerization of an epoxy compound. Further, from the viewpoint of productivity, the hardening is preferably carried out by irradiation with an active energy ray.

From the viewpoints of weather resistance, refractive index, cationic polymerizability, and the like, it is preferred that the epoxy compound contained in the curable adhesive composition does not contain an aromatic ring in the molecule. Examples of the epoxy compound which does not contain an aromatic ring in the molecule include a hydrogenated epoxy compound, an alicyclic epoxy compound, and an aliphatic epoxy compound. An epoxy compound which can be suitably used for such a hardenable adhesive composition, for example, in Japanese Laid-Open Patent Publication No. 2004-245925 Detailed description, but here is a brief description.

The hydrogenated epoxy compound may be a cyclic hydrogenated polyhydroxy compound obtained by selectively performing a nuclear hydrogenation reaction in the presence of a catalyst and an aromatic polyhydroxy compound in a raw material of an aromatic epoxy compound. Oxypropyl propyl etherification. The aromatic polyhydroxy compound which is a raw material of the aromatic epoxy compound is, for example, bisphenols of bisphenol A, bisphenol F and bisphenol S; phenolic phenolic resin, cresol novolac resin and phenolic phenolic phenolic resin Resin type resin; a compound of a polyfunctional type of tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. The above-mentioned aromatic polyhydroxy compound is subjected to a nuclear hydrogenation reaction, and the obtained nuclear hydrogenated polyhydroxy compound is reacted with epichlorohydrin to carry out epoxypropyl etherification. As a suitable hydrogenated epoxy compound, the hydrogenated bisphenol A glycopropyl ether is mentioned, for example.

The 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 the alicyclic ring" means a bridged oxygen atom -O- in the structure represented by the following formula, wherein m is an integer of 2 to 5.

A group in which one or a plurality of hydrogen atoms in the formula (CH ₂ ) _m are removed and bonded to another chemical structure may be an alicyclic epoxy compound. Further, one or a plurality of hydrogen atoms of (CH ₂ ) _m forming an alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy compounds, from the viewpoint of exhibiting good adhesion, it is preferred to use an oxabicyclohexyl ring (in the above formula, m=3) or an oxabicycloheptane (in the above formula m=4). Epoxy compound. Specific examples of the alicyclic epoxy compound are disclosed below. Here, first, the compound names are exemplified, and then the corresponding chemical formulas are shown, and the compound names and the chemical formulas corresponding thereto are given the same symbols.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylic acid, B: 3,4-epoxy group of 3,4-epoxy-6-methylcyclohexanecarboxylic acid -6-methylcyclohexylmethyl ester, C: exoethyl bis(3,4-epoxycyclohexanecarboxylate), D: bis(3,4-epoxycyclohexylmethyl) adipate Ester, E: bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: diethylene glycol bis(3,4-epoxycyclohexylmethyl ether), G: ethylene glycol bis(3,4-epoxycyclohexylmethyl ether), H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxa trispiro [5.2.2.5.2.2] Behenane, I: 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5] Alkane, J: 4-vinylcyclohexene dioxide, K: limonene dioxide L: bis(2,3-epoxycyclopentyl) ether, M: dicyclopentadiene dioxide, and the like.

The aliphatic epoxy compound may be a polyepoxypropyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. More specifically, diepoxypropyl ether of propylene glycol; diepoxypropyl ether of 1,4-butanediol; two of 1,6-hexanediol Epoxypropyl ether; triepoxypropyl ether of glycerol; triepoxypropyl ether of trimethylolpropane; by aliphatic polyol addition ring such as ethylene glycol, propylene glycol and glycerol A polyepoxypropyl ether of a polyether polyol obtained from oxyalkylene (ethylene oxide or propylene oxide) (for example, a di-epoxypropyl ether of polyethylene glycol).

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

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

From the viewpoint of reactivity, cationic polymerization is preferred as the curing reaction of the epoxy compound. Therefore, it is preferred to formulate a cationic polymerization initiator in the curable adhesive composition containing an epoxy compound. The cationic polymerization initiator generates a cationic substance or a Lewis acid by irradiation or heating of an active energy ray such as visible light, ultraviolet rays, X-rays, and electron rays to initiate polymerization of an epoxy group. From the viewpoint of workability, it is preferred to impart a latent property to the cationic polymerization initiator. Hereinafter, a cationic polymerization initiator which generates a cationic substance or a Lewis acid by irradiation of an active energy ray and initiates polymerization of an epoxy group is referred to as a "photocationic polymerization initiator". A cationic polymerization initiator which initiates polymerization of an epoxy group by generating a cationic substance or a Lewis acid by heat is called a "thermal cationic polymerization initiator".

The photocationic polymerization initiator is used to cure the adhesive composition by irradiation with an active energy ray, and it can be cured under normal temperature and normal humidity, and the heat resistance of the polarizing film or the necessity of distortion due to expansion is reduced. It is advantageous at a point where the protective film and the polarizing film can be well adhered. Further, the photocationic polymerization initiator is excellent in storage stability and workability even when it is mixed with an epoxy compound due to a photocatalytic action of light.

The photocationic polymerization initiator may, for example, be an aromatic diazonium salt; for example, an aromatic onium salt, an onium salt of an aromatic sulfonium salt, an iron-aromatic hydrocarbon complex or the like. The compounding amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less based on 100 parts by weight of the epoxy compound.

When the amount of the photo-cationic polymerization initiator is less than 0.5 part by weight based on 100 parts by weight of the epoxy compound, the curing is insufficient, and the mechanical strength and the subsequent strength of the cured product tend to be lowered.

On the other hand, when the amount of the photocationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy compound, the ionic substance in the cured product increases, and the hygroscopic property of the cured product becomes high, and durability can be improved. The possibility of reduction.

When a photocationic polymerization initiator is used, the curable adhesive composition may further contain a photosensitizer as needed. By using a photosensitizer, the reactivity of cationic polymerization can be improved, and the mechanical strength and the subsequent strength of the cured product can be improved. As a photosensitizer, such as carbonyl compounds, organic sulfuration A substance, a persulfide compound, a redox compound, an azo compound, a diazo compound, a halide, a photoreductive dye, or the like. When the photo-sensitizer is blended, the amount thereof is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the curable adhesive composition, and in order to increase the curing rate, for example, an increase in naphthoquinone derivatives may be used. Sensitive additives.

On the other hand, examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenylsulfonium salt, tetrahydrothiophene phosphonium salt, benzylammonium salt, pyridinium salt, hydrazinium, and carboxylate. Acid esters, sulfonates, amine imines, and the like.

The curable adhesive composition containing an epoxy compound is preferably cured by photocationic polymerization as described above, but the thermal cationic polymerization initiator may be present, or may be cured by thermal cationic polymerization, or may be used in combination. Photocationic polymerization and thermal cationic polymerization. In the case of photocationic polymerization and thermal cationic polymerization, it is preferred that both the photocationic polymerization initiator and the thermal cationic polymerization initiator are contained in the curable adhesive composition.

Further, the curable adhesive composition may further contain a compound which promotes cationic polymerization such as an oxetane compound or a polyol compound. The oxetane compound is a compound having a 4-membered cyclic ether in its molecule. When the oxetane compound is blended, the amount thereof is usually from 5 to 95% by weight, preferably from 5 to 50% by weight, based on the composition of the curable adhesive. Further, the polyol compound may be an alkylene glycol or an oligomer thereof comprising ethylene glycol, hexanediol, polyethylene glycol or the like, a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol or the like. When the polyol compound is formulated, the amount thereof is usually 50% by weight or less, preferably 30% by weight or less, based on the composition of the curable adhesive. under.

Further, the curable adhesive composition may contain other additives such as an ion trapping agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, and a flow regulator as long as the adhesion is not impaired. , plasticizers, defoamers, etc. The ion scavenger may, for example, be a powdery lanthanum, lanthanide, magnesium, aluminum, calcium, or titanium, or an inorganic compound containing such a mixed system, and examples of the antioxidant include hindered phenolic resistance. Oxidizing agents, etc.

Applying the curable adhesive composition containing an epoxy compound to the adhesion surface of the polarizing film or the protective film or the adhesion surface of the both, and bonding the surface coated with the adhesive to irradiate the active energy Wire or heat to harden the uncured adhesive layer, followed by a polarizing film and a protective film. As a coating method of an adhesive agent, various coating methods, such as a doctor blade, a wire bar, a slit coater, a notch coater, and a gravure coater can be employ|adopted.

The curable adhesive composition can be basically used as a solventless adhesive which does not substantially contain a solvent. However, since each coating method has various suitable viscosity ranges, a solvent may be contained in order to adjust the viscosity. The solvent is preferably such that the optical properties of the polarizing film are not lowered, and the organic solvent of each component including an epoxy compound can be satisfactorily dissolved. For example, a hydrocarbon represented by toluene or an ester represented by ethyl acetate can be used.

When the adhesive composition is cured by irradiation with an active energy ray, various types of the above-described various types can be used as the active energy ray. However, since it is easy to handle, it is also easy to control the amount of light to be irradiated, and the like, and it is preferable to use ultraviolet rays. Active energy rays, such as ultraviolet radiation intensity, exposure, do not affect In the range of various optical properties including the transparency of the polarizing film and the transparency and phase difference characteristics of the protective film, the optical productivity can be appropriately determined in such a manner that appropriate productivity can be maintained.

When the adhesive composition is hardened by heat, it can be heated by a generally known method. Usually, the thermal cationic polymerization initiator which is blended in the curable adhesive composition is heated at a temperature higher than the temperature at which the cationic substance and the Lewis acid are generated. Specifically, the heating temperature is, for example, about 50 to 200 °C.

[adhesive]

The adhesive is excellent in optical transparency, and is excellent in adhesion properties such as moderate wettability, aggregation, and adhesion. However, it is preferable to further improve durability. Specifically, as the adhesive for forming the adhesive layer, an adhesive (acrylic adhesive) containing an acrylic resin is preferable.

The acrylic resin contained in the acrylic adhesive is a resin containing, as a main monomer, an alkyl acrylate such as butyl acrylate, ethyl acrylate, isooctyl acrylate or 2-ethylhexyl acrylate. The acrylic resin is usually a copolymer of a polar monomer, and a polar monomer refers to a compound having a polymerizable unsaturated bond and a polar functional group. Here, a polymerizable unsaturated bond is generally formed from (A). Further, the polar functional group may be a carboxyl group, a hydroxyl group, a decylamino group, an amine group, an epoxy group or the like. Specific examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydrocarbylethyl (meth)acrylate, (meth)acrylamide, (methyl) 2-N,N-dimethylaminoethyl acrylate, (meth) propylene Acid glycidyl ester and the like.

Further, a crosslinking agent is usually blended with an acrylic resin in an acrylic adhesive.

A typical example of the crosslinking agent is, for example, an isocyanate compound having at least two isocyanate groups (-NCO) in the molecule.

Various additives can be formulated for the adhesive. As a suitable additive, a decane coupling agent, a charging prevention agent, etc. are mentioned, for example. The decane coupling agent is effective in increasing the adhesion to the glass. The charge preventing agent is effective in reducing or preventing the generation of static electricity.

The adhesive layer can be directly applied to a polarizing film or a protective film by preparing an adhesive composition in which an adhesive component as described above is dissolved in an organic solvent, drying or removing the solvent, or by Applying the above-mentioned adhesive composition to a release-treated surface of a base film formed of a resin film subjected to a release treatment, drying and removing the solvent to form an adhesive layer, and attaching the adhesive film to the transparent protective film. A method of transferring an adhesive layer is formed. When the adhesive layer is formed on the transparent protective film by the direct coating method of the former, the resin film (also referred to as a separation film) subjected to the release treatment is attached to the surface thereof, and the adhesive is temporarily protected until use. The surface of the agent layer is a general case. The latter transfer method is often used from the viewpoint of handleability of the adhesive composition of the organic solvent solution, etc., and in this case, the base film which is first used for the release treatment of the adhesive layer is attached to the polarized light. It can also be directly used as a separation membrane after the plate, which is also suitable.

Before the polarizing film or the protective film build-up adhesive, the polarizing film surface, the protective film surface, and the adhesive surface are pre-corona treated and plasma-treated. Processing can be used.

[Adhesive layer 33, 53, and subsequent layer 54]

In the bonding between the polarizing plate and the liquid crystal cell, an adhesive layer can be used, and the adhesive polarizing plate 50 and the brightness enhancing film 61 can be bonded together, and an adhesive or an adhesive can be used, and any adhesive is used as an adhesive. Preferably. The adhesive layer layer is excellent in optical transparency, and includes excellent adhesion properties such as moderate wettability, aggregation, and adhesion, and is excellent in durability and the like. Specifically, as the adhesive forming the pressure-sensitive adhesive layer, an adhesive (acrylic adhesive) containing an acrylic resin is preferable.

As the adhesive layer, the same as those used for bonding the polarizing film and the protective film described above can be used. Adhesives can be used separately or in the same way.

Before the polarizing plate is laminated with an adhesive, corona treatment or plasma treatment may be applied to the polarizing film surface, the protective film surface, and the adhesive surface in advance. Further, when the brightness-increasing film is laminated, the bonding surface and the adhesive surface of the brightness enhancement film 61 may be used in advance for corona treatment or plasma treatment. From the viewpoint that the brightness enhancement film 61 is close to the liquid crystal cell, the adhesive layer used for the laminate of the brightness enhancement film is preferably 25 μm or less. More preferably, it is 15 μm or less. Usually, the thickness of the adhesive layer is 3 μm or more.

In the set of polarizing plates of the present invention described above, in the viewing-side polarizing plate 30, the absorption axis of the polarizing film 32 is approximately parallel to the longitudinal direction of the liquid crystal cell, and the absorption axis of the polarizing film 52 on the back side polarizing plate 60 is It is preferred that the short side directions of the liquid crystal cells are approximately parallel.

[liquid crystal cell]

The liquid crystal cell system has two cell substrates and a liquid crystal layer interposed between the substrates. The cell substrate is generally composed of glass, but may be a plastic substrate. Others, the liquid crystal cell itself used in the liquid crystal panel of the present invention can be constituted by various liquid crystal cells (for example, IPS mode, VA mode, TN mode, or the like as a driving mode) employed in the field.

[LCD panel]

A liquid crystal panel can be produced by bonding a polarizing plate to a liquid crystal cell via an adhesive layer.

In the liquid crystal panel of the present invention, the distance from the liquid crystal cell to the brightness enhancement film is 100 μm or less, and the dimensional change rate in the absorption axis direction when the viewing side polarizing plate is heated at 85 ° C for 100 hours is included in the absorption axis direction of the back side polarizing plate. When the absorption type polarizing plate is heated at 85 ° C for 100 hours, the ratio of the dimensional change ratio in the absorption axis direction is 0.62 or more and 1.25 or less.

From the other viewpoints, the absolute value of the amount of warpage of the liquid crystal panel of the present invention when heated at 85 ° C for 240 hours is 0.5 mm or less, preferably 0.3 mm or less. By laminating such a set of polarizing plates to a liquid crystal cell, the liquid crystal panel of the present invention is a liquid crystal display panel in which warpage in a high-temperature environment is suppressed and can be accommodated in a casing of a final product.

The liquid crystal panel of the present invention is particularly suitably used for a small-to-medium-sized liquid crystal display device which is exposed to a high temperature such as a house. For example, it is suitable for the case where the size of the liquid crystal panel is 15 angstroms or less.

Moreover, the warpage of the liquid crystal panel in a high temperature environment can be further reduced, and the distance from the liquid crystal cell to the brightness enhancement film is 90 μm or less. Preferably, it is preferably 80 μm or less, and may be 60 μm or less. In addition, the dimensional change rate in the absorption axis direction when the viewing-side polarizing plate was heated at 85 ° C for 100 hours and the absorption axis direction when the absorption-type polarizing plate contained in the back-side polarizing plate was heated at 85 ° C for 100 hours The ratio of the rate of change is preferably 0.65 or more and 1.2 or less, more preferably 0.7 or more and 1.15 or less.

The dimensional change ratio in the absorption axis direction when the viewing-side polarizing plate is heated at 85 ° C for 100 hours is preferably 0.8% or more, more preferably 1.0% or more. The dimensional change rate in the absorption axis direction when the absorption-type polarizing plate contained in the back side polarizing plate is heated at 85 ° C for 100 hours is preferably 1.4% or less, more preferably 1.3% or less. In addition, the dimensional change rate of the polarizing plate in the absorption axis direction 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.

Further, after the polarizing plate is produced, a method of adjusting the dimensional change rate in the absorption axis direction of the polarizing plate by heat treatment in a range of 40 ° C to 80 ° C can be used. From the viewpoint of avoiding appearance defects due to rapid shrinkage of the polarizing plate, it is more preferable to carry out heat treatment in the range of 40 ° C to 60 ° C.

The dimensional change rate in the absorption axis direction when the polarizing plate was heated at 85 ° C for 100 hours was measured as follows. First, the polarizing plate was cut into a size of 100 mm in the longitudinal direction and 100 mm in the width direction, and allowed to stand in an environment of a temperature of 23 ° C and a humidity of 55% for one day, and the size (L0) in the MD direction (absorption axis direction) was measured. Then, it was allowed to stand in an environment of 85 ° C for 100 hours, and the size (L1) in the MD direction after standing in a high temperature environment was measured. As a result, the dimensional change rate (%) was obtained from the formula (c).

Dimensional change rate (%) = [(L0-L1) / L0] × 100 (c)

The ratio of the dimensional change ratio is determined by the following formula (d) from the dimensional change ratio A of the viewing-side polarizing plate and the value of the dimensional change ratio B of the absorbing polarizing plate included in the back-side polarizing plate.

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

In addition, the layer structure of the polarizing plate for measuring the dimensional change rate is applied to the adhesive layer or other film of the liquid crystal panel in a state in which the polarizing film is bonded to the single or both surfaces of the polarizing film, and is removed. The measurement was carried out. When the back side polarizing plate is a laminate of an absorbing polarizing plate and a brightness enhancement film, the dimensional change rate of the absorbing polarizing plate before the brightness enhancing film is attached or the absorbing polarizing plate remaining after removing the brightness enhancing film is measured.

[Examples]

Hereinafter, the present invention will be described more specifically by way of examples, but the invention is not limited to the examples. In the examples, the parts and % of the content to the amount used are indicated on a weight basis unless otherwise specified. In addition, the measurement of each physical property of the following examples was performed by the following methods.

(1) Determination of thickness:

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

(2) Determination of in-plane hysteresis and thickness direction hysteresis:

The phase difference meter "KORBRA (registered trademark) - WPR" which is a principle of the parallel Nikon rotation method manufactured by Oji Scientific Instruments Co., Ltd. was used to measure the in-plane hysteresis and the thickness direction hysteresis at a wavelength of 590 nm at a temperature of 23 °C.

(3) Dimensional change rate

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

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

The produced liquid crystal panel was left to stand in an environment of 85 ° C for 240 hours, and then placed on the measuring table of the two-dimensional measuring device "NEXIV VMR-12072" manufactured by Nikon Corporation, with the viewing side polarizing plate as the upper side. Then, focusing on the surface of the measuring table, focusing on the center of each of the four corners and four sides of the liquid crystal panel and the center of the surface of the liquid crystal panel, and measuring the distance from the measuring table after the distance from the reference focus is used as a reference. The longest distance in absolute value is used as the amount of warpage.

[Manufacturing Example 1] Production of Polarizing Film 1

A polyvinyl alcohol film having a thickness of 30 μm (having an average degree of polymerization of about 2400 and a degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 4 times by dry stretching, and further immersed in a state of being tightly immersed at 40 ° C. After 40 seconds of pure water, it was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.052/5.7/100 at 28 ° C for 30 seconds to carry out a dyeing treatment. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 11.0/6.2/100 at 70 ° C for 120 seconds. Then, after washing with pure water of 8 ° C for 15 seconds, the film was dried at 60 ° C for 50 seconds while maintaining a tension of 300 N, and then dried at 75 ° C for 20 seconds to obtain an iodine adsorption orientation to the polyvinyl alcohol film. An absorbing polarizing film having a thickness of 12 μm.

[Production Example 2] Production of a water-based adhesive

100 parts by weight of water, 3 parts by weight of carboxyl modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd.] was dissolved in the water. To the liquid, 1.5 parts by weight of a water-soluble epoxy resin-based polyamine-based epoxy-based additive ("SUMIREZ RESIN (registered trademark) 650 (30)", which is obtained from the company of Takaoka Chemical Industry Co., Ltd., and a solid concentration of 30% by weight. Aqueous solution], a water-based adhesive was prepared.

[Adhesive A, B]

Prepare the following three types of adhesives.

Adhesive A: Sheet adhesive of 20 μm thickness [NCF #KT" by Lintec Co., Ltd.

Adhesive B: sheet adhesive having a thickness of 5 μm [NCF #L2" manufactured by Lintec Co., Ltd.]

Adhesive C: sheet adhesive having a thickness of 15 μm [NCF #L1" manufactured by Lintec Co., Ltd.]

[Protective film A, C, D]

Prepare the following three types of protective films.

Protective film A: a hard-coated triethylenesulfonated cellulose film made by Konica Minolta Co., Ltd.; 25KCHCN-TC (thickness 32 μm)

Protective film C: a cyclic polyolefin resin film manufactured by Japan ZEON Co., Ltd.; ZF14-013 (thickness 23 μm, in-plane retardation value at a wavelength of 590 nm = 0.5 nm, thickness direction at a wavelength of 590 nm = 4.3 nm)

Protective film D: triethylenesulfonyl cellulose film manufactured by Konica Minolta Co., Ltd.; KC2UA (thickness 25 μm)

[Brightness Film A]

Prepare the following brightness enhancement film.

Brightening film A: Brightening film with a thickness of 26 μm (made by 3M Company, trade name) Advanced Polarized Film, Version 3)

[Manufacturing Example 3] Production of Viewing Side Polarizing Plate 1

The protective film A is subjected to saponification treatment, and corona treatment is performed on one surface of the protective film C. The protective film A, the polarizing film 1, and the protective film C are bonded to the polarizing film 1 by a water-based adhesive, in which the triacetyl cellulose surface of the protective film A and the corona-treated surface of the protective film C are bonded to the polarizing film 1, respectively. The drying treatment was carried out to obtain a viewing-side polarizing plate 1.

The dimensional change rate in the MD direction of the viewing side polarizing plate 1 was 1.4%. Furthermore, the dimensional change rate is adjusted by adjusting the drying time of the drying process described above.

Further, on the protective film C of the viewing-side polarizing plate 1, the adhesive A is bonded to form an adhesive layer. At this time, corona treatment was performed in advance on the surface of the protective film and the surface of the adhesive.

[Manufacturing Examples 4 to 10] Production of Viewing Side Polarizing Plates 2 to 8

The viewing-side polarizing plates 2 to 8 were produced in the same manner as in Production Example 3, except that the drying time of the drying treatment was adjusted, and the dimensional change rates in the MD direction (absorption axis direction) were different. Adhesive A is applied to C to form an adhesive layer. The dimensional change rate of the viewing side polarizing plates 2 to 8 is as follows.

Viewing side polarizer 2: 1.28

Viewing side polarizer 3: 1.11

Viewing side polarizer 4:1.05

View side polarizer 5: 0.99

Viewing side polarizer 6: 0.88

Viewing side polarizer 7: 1.63

Viewing side polarizer 8: 0.76

[Manufacturing Example 11] Production of Back Side Polarizing Plate 1

The protective film D is subjected to saponification treatment, and corona treatment is performed on one surface of the protective film C. The protective film D, the polarizing film 1, and the protective film C are bonded to each other by a water-based adhesive in which the triacetyl cellulose surface of the protective film D and the corona-treated surface of the protective film C are bonded to the polarizing film 1, respectively. , an absorption type polarizing plate is obtained. The dimensional change rate of the absorption-type polarizing plate obtained in the absorption axis direction was 1.25%. Then, the adhesive B was bonded to the surface of the protective film D of the obtained absorptive polarizing plate to form an adhesive layer. At this time, corona treatment is performed in advance on the surface of the protective film D and the surface of the adhesive B. Then, the surface of the adhesive B on the side opposite to the surface on which the protective film D is bonded is bonded to the brightness enhancement film A to form the back side polarizing plate 1. At this time, the surface of the brightness enhancement film A was subjected to corona treatment in advance.

The adhesive A was bonded to the surface of the protective film C of the back side polarizing plate 1 obtained in this manner to form an adhesive layer. At this time, corona treatment was also performed in advance on the surface of the protective film C and the surface of the adhesive A.

[Manufacturing Example 12] Production of Back Side Polarizing Plate 2

The protective film D is subjected to saponification treatment, and corona treatment is performed on one surface of the protective film C. The triacetyl cellulose surface of the protective film D and the corona-treated surface of the protective film C are bonded to the polarizing film 1, and the protective film D, the polarizing film 1, and the protective film C are bonded together with a water-based adhesive to be dried. The treatment was carried out to obtain an absorbing polarizing plate. The dimensional change rate of the absorption-type polarizing plate obtained in the absorption axis direction was 0.91%. Furthermore, by adjusting the drying time of the above drying process, Adjust the dimensional change rate. Then, on the surface of the protective film D of the obtained absorption type polarizing plate, the adhesive C was bonded to form an adhesive layer. At this time, corona treatment is performed in advance on the surface of the protective film D and the surface of the adhesive C. Then, the surface of the adhesive C on the side opposite to the surface on which the protective film D is bonded is bonded to the brightness enhancement film A to form the back side polarizing plate 2. At this time, the surface of the brightness enhancement film A was subjected to corona treatment in advance. The adhesive A was bonded to the surface of the protective film C of the back side polarizing plate 2 obtained in this manner to form an adhesive layer. At this time, corona treatment was also performed in advance on the surface of the protective film C and the surface of the adhesive A.

[Production Example 13] Production of Back Side Polarizing Plate 3

The protective film D is subjected to saponification treatment, and corona treatment is performed on one surface of the protective film C. The protective film D, the polarizing film 1, and the protective film C are bonded to each other by a water-based adhesive in which the triacetyl cellulose surface of the protective film D and the corona-treated surface of the protective film C are bonded to the polarizing film 1, respectively. Drying treatment was carried out to obtain an absorbing polarizing plate. The dimensional change rate of the absorption-type polarizing plate obtained in the absorption axis direction was 0.91%. Furthermore, the dimensional change rate is adjusted by adjusting the drying time of the drying process described above. Then, the adhesive A was bonded to the surface of the protective film D of the obtained absorptive polarizing plate to form an adhesive layer. At this time, corona treatment is performed in advance on the surface of the protective film D and the surface of the adhesive A. Then, the brightness enhancement film A is bonded to the surface of the adhesive A on the side opposite to the surface to which the protective film D is bonded, and the back side polarizing plate 3 is produced. At this time, the surface of the brightness enhancement film A was subjected to corona treatment in advance. The adhesive A was bonded to the surface of the protective film C of the back side polarizing plate 3 obtained in this manner to form an adhesive layer. At this time, corona treatment was also performed in advance on the surface of the protective film C and the surface of the adhesive A.

[liquid crystal cell]

The liquid crystal cell was obtained by peeling off the viewing side polarizing plate and the back side polarizing plate from the liquid crystal panel of the Nexus 7 manufactured by Google Inc.

[Example 1]

The viewing side polarizing plate 1 cuts the long side of the liquid crystal cell into a diagonal of 7 以 so that the absorption axis of the polarizing film becomes parallel, and the rear side polarizing plate 1 has the absorption axis of the polarizing film on the short side of the liquid crystal cell. It is cut into a diagonal of 7 inches in a parallel manner. The polarizing plate produced in this manner was bonded to the liquid crystal cell via an adhesive, and a liquid crystal panel was produced. The ratio of the dimensional change ratio of the viewing side polarizing plate to the back side polarizing plate was 1.12. Moreover, the distance from the brightness enhancement film to the liquid crystal cell was 85 μm.

The liquid crystal panel produced in this manner was allowed to stand in an environment of 85 ° C for 240 hours, and then the amount of warpage was measured to be 0.4 mm.

[Examples 2 to 8, Comparative Examples 1 to 2]

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, and the amount of warpage of the liquid crystal panel was measured.

The dimensional change ratio in the absorption axis direction of the viewing-side polarizing plate used in Examples 1 to 8 and Comparative Examples 1 to 2, and the dimensional change rate in the absorption axis direction of the absorption-type polarizing plate included in the back-side polarizing plate, The ratio of the distance from the brightness enhancement film to the liquid crystal cell of the back side polarizing plate and the dimensional change rate is summarized in Table 1.

[Industry use possibility]

According to the present invention, it is possible to obtain a liquid crystal panel which can eliminate the warpage of the liquid crystal panel in a high temperature environment and which is housed in the casing of the final product in a high temperature environment.

30‧‧‧ viewing side polarizer

31a, 31b, 51a, 51b‧‧‧ protective film

32, 52‧‧‧ polarizing film

35‧‧‧Surface treatment layer

33, 53‧‧‧Adhesive layer

50‧‧‧Absorbing polarizer

54‧‧‧Next layer

60‧‧‧Back side polarizer

61‧‧‧Brightening film

Claims (4)

A kit of polarizing plates disposed on a viewing side polarizing plate on a viewing side of a liquid crystal cell and a rear side polarizing plate disposed on a back side of the liquid crystal cell, wherein the back side polarizing plate has a brightness enhancing film When the absorption-type polarizing plate is laminated on the back side of the liquid crystal cell, the distance from the surface of the liquid crystal cell to the brightness enhancement film is 100 μm or less, and the viewing-side polarizing plate is heated at 85 ° C for 100 hours. The ratio of the dimensional change of the absorption axis direction at the time of the absorption axis direction of the absorption-type polarizing plate contained in the back side polarizing plate to the absorption axis direction at 85 ° C for 100 hours is 0.62 or more and 1.25 or less. The polarizing plate set according to the first aspect of the invention, wherein the viewing side polarizing plate and the back side polarizing plate respectively have a polarizing film, and the viewing side polarizing plate has a thickness of the polarizing film and the back side polarizing The thickness of the polarizing film of the board is 15 μm or less. A liquid crystal panel comprising the polarizing plate set and the liquid crystal cell according to claim 1 or 2, wherein the viewing-side polarizing plate has an absorption axis which is approximately parallel to a longitudinal direction of the liquid crystal cell, and the back surface The side polarizer has an absorption axis substantially parallel to the short side direction of the liquid crystal cell. The liquid crystal panel according to claim 3, wherein the viewing-side polarizing plate is disposed on a viewing side of the liquid crystal cell, and the back-side polarizing plate is disposed on a back surface of the liquid crystal cell On the side, the absolute value of the warpage amount of the liquid crystal panel when heated at 85 ° C for 240 hours was 0.5 mm or less.