TW201814377A - Liquid crystal panel, liquid crystal display device, and polarizer kit wherein the liquid crystal panel is hard to warp by making the thickness of the second polarizing element greater than that of the first polarizing element - Google Patents

Abstract

A liquid crystal panel of the present invention is provided with a liquid crystal cell, a first polarizing element disposed on the first surface side of the liquid crystal cell and having a substantially rectangular shape, and a second polarizing element disposed on the second surface side of the liquid crystal cell and having a substantially rectangular shape. The first polarizing element has an absorption axis extending in its longitudinal direction, and the second polarizing element has an absorption axis extending in the short direction. The first polarizing element and the second polarizing element are disposed in such a way that the extension direction of each absorption axis of the two polarizing elements intersects perpendicularly, and the thickness of the second polarizing element is greater than that of the first polarizing element. Therefore, the liquid crystal panel is hard to warp.

Description

Set of liquid crystal panel, liquid crystal display device, and polarizer

The present invention relates to a liquid crystal panel and the like.

Generally, a liquid crystal panel of a liquid crystal display device includes a liquid crystal cell, a first polarizer provided on the first surface side of the liquid crystal cell, and a second polarizer provided on the second surface side (opposite side of the first surface side) of the liquid crystal cell. . In the case of polarizers used for liquid crystal panels, polarizers obtained by adsorbing and stretching a dichroic substance such as iodine on a resin film containing a polyvinyl alcohol resin or the like are widely used. In this way, the polarizer is easily contracted in the extending direction due to the influence of heat or humidity. Therefore, in a high temperature or humid environment, the first surface of the liquid crystal cell is affected by the shrinking force of the first polarizer, and the second surface of the liquid crystal cell is affected by the shrinking force of the second polarizer. Therefore, the liquid crystal cell Will easily warp. As a result, a problem such as warping occurs in the entire liquid crystal panel including the liquid crystal cell and the two polarizers. When the liquid crystal panel is warped, problems such as light leakage or display unevenness easily occur in the liquid crystal display device. Therefore, this problem needs to be improved.

Patent Document 1 discloses a polarizing plate having a total thickness of a polarizer and a protective film of 135 μm or less, a resin layer between the polarizer and the protective film, or a surface of the polarizer, and a dimensional change rate in an absorption axis direction of 0.40% or less And reveals the use of its polarizer for LCD panels. The polarizing plate reduces the warpage of the polarizing plate accompanying the shrinkage of the polarizing material through the resin layer lining the polarizing material, so that warping of the liquid crystal panel can be prevented. However, the problem of warping of the liquid crystal panel accompanying the shrinkage of the polarizer has not yet been fully solved, and further improvement is needed.

[Preceding Technical Documents] [Patent Documents] Patent Document 1: Japanese Patent Laid-Open No. 2002-372621

SUMMARY OF THE INVENTION Problems to be Solved by the Invention The object of the present invention is to provide a liquid crystal panel and the like which can effectively prevent warpage.

Means for Solving the Problems The liquid crystal panel of the present invention includes a liquid crystal cell, a first polarizer that is provided on the first surface side of the liquid crystal cell and is slightly rectangular, and a liquid crystal panel that is provided on the second surface side of the liquid crystal cell and is slightly rectangular. A second polarizer; the first polarizer has an absorption axis extending in a long direction thereof, and the second polarizer has an absorption axis extending in a short direction thereof; the first polarizer and the second polarizer are disposed so that The extension directions of the absorption axes of each other are perpendicularly intersected, and the thickness of the second polarizer is greater than the thickness of the first polarizer.

The ratio (T1 / T2) of the thickness (T1) of the first polarizer to the thickness (T2) of the second polarizer is preferably 1/10 to 1/2. The difference (T2-T1) between the thickness (T2) of the second polarizer and the thickness (T1) of the first polarizer is preferably 2 μm or more. Further, it is preferable that a protective film is laminated on at least one of the first polarizer and the second polarizer.

According to another aspect of the present invention, a liquid crystal display device equipped with the liquid crystal panel of the present invention can be provided.

According to another aspect of the present invention, a polarizer set can be provided. The polarizing element set of the present invention has a slightly rectangular first polarizing element and a slightly rectangular second polarizing element; the first polarizing element has an absorption axis extending in its long direction, and the second polarizing element has its short direction The extended absorption axis; the first polarizer and the second polarizer are arranged so that the extension directions of the absorption axes intersect at right angles, and the thickness of the second polarizer is greater than the thickness of the first polarizer.

ADVANTAGE OF THE INVENTION The liquid crystal panel of this invention has the 1st polarizer of a slightly rectangular shape, and the 2nd polarizer of a slightly rectangular shape. The said 1st polarizer has the absorption axis extended in the long direction, and the said 2nd polarizer has the short direction extended. The first polarizer and the second polarizer are arranged so that the extension directions of the absorption axes intersect at right angles, and further the thickness of the second polarizer is greater than the thickness of the first polarizer. Therefore, in the liquid crystal cell, the deformation stress generated by the shrinkage of the first polarizer and the deformation stress generated by the shrinkage of the second polarizer can be well balanced, and as a result, warping of the liquid crystal panel can be effectively prevented.

Modes for Carrying Out the Invention Hereinafter, a configuration example of a liquid crystal display device having a liquid crystal panel of the present invention will be described with reference to the drawings, and then the liquid crystal panel of the present invention will be described. Please also note that in the drawings, dimensions such as thickness and size are different from actual ones. In addition, in this specification, ordinal numbers such as "1" or "2" may be added before the terms. However, the ordinal numbers are added to distinguish the terms, and do not have special meanings such as the pros and cons of the terms. . In addition, the angle and its relationship (for example, perpendicular intersection and parallel) include an error range allowed in the technical field to which the present invention pertains. For example, vertical intersection includes a strict angle (90 °) ± 5 °, and preferably a range of ± 3 °. The same is true for parallel. Furthermore, in this specification, the numerical range shown by "lower limit value XXX ~ upper limit value YYY" means the lower limit value XXX or more and the upper limit value YYY or less. When the foregoing numerical range is a plurality of individual records, an arbitrary lower limit value and an arbitrary upper limit value can be selected and set to "arbitrary lower limit value ~ arbitrary upper limit value".

[Configuration Example of Liquid Crystal Display Device] FIG. 1 shows an example of a liquid crystal display device 10 including a liquid crystal panel 1 of the present invention. In FIG. 1, the upper side of the paper surface is the visible surface side (the side where the image of the liquid crystal display device can be seen), and the lower side of the paper surface is the reverse visible surface side (the opposite side to the visible surface side). As shown in the figure, the liquid crystal display device 10 includes a liquid crystal panel 1, a light source 2, and a bezel 3 that holds the liquid crystal panel 1 and the light source 2.

Here, in general, the liquid crystal display device 10 can be roughly classified into a reflective type, a transmissive type, and a semi-transmissive type according to the arrangement of the light sources 2 inside thereof. In the reflective liquid crystal display device 10, the light source 2 (front light) is arranged on the visible side of the liquid crystal panel 1, or the light source 2 (side light) is arranged on the side of the liquid crystal cell 4, and the front is provided by a reflecting plate. The light or side light is reflected to perform image display. In addition, in the reflective liquid crystal display device 10, the light of a fluorescent lamp or sunlight outside the liquid crystal display device 10 is also used as the light source 2. In the transmissive liquid crystal panel 1, a light source 2 (backlight) is arranged on the side of the viewing surface of the liquid crystal panel 1, and the light of the backlight is transmitted to perform image display. The transflective liquid crystal panel 1 includes both the transmissive type and the reflective type. The transflective liquid crystal panel 1 uses a backlight light source 2 to display images in a dark place, and reflects sunlight to display images in a bright place.

The liquid crystal display device 10 shown in FIG. 1 is a transmissive liquid crystal display device having a light source 2 (backlight) on the side of the viewing surface of the liquid crystal panel 1. Of course, the liquid crystal panel 1 of the present invention can be mounted not only on the transmissive liquid crystal display device 10 but also on a reflective or semi-transmissive liquid crystal display device 10 (not shown). The light emitted from the light source 2 (backlight) passes through the liquid crystal panel 1, and thereby becomes emitted light containing image information. The emitted light containing image information is light that is visible to an observer as an image projected on the liquid crystal display device 10. Specifically, the liquid crystal panel 1 is connected with a control means (not shown) such as a microcomputer including a calculation processing unit or a memory unit. Through the control of this control means, the light that has passed through the liquid crystal panel 1 becomes the emitted light containing image information. Hereinafter, the liquid crystal panel 1 according to the first embodiment including the liquid crystal display device 10 will be described, and then the liquid crystal panel 1 according to the second to fourth embodiments will be described.

[About the liquid crystal panel of the first embodiment] FIGS. 2 and 3 show an example of the liquid crystal panel 1 included in the liquid crystal display device 10. In this embodiment, the liquid crystal panel 1 will be described by referring to the paper surface side shown in FIGS. 2 and 3 as the first surface side and the paper surface lower side as the second surface side. The liquid crystal panel 1 includes a liquid crystal cell 4, a slightly rectangular first polarizer 5 a provided on the first surface side of the liquid crystal cell 4, and a second rectangular polarizer 5 b provided on the second surface side of the liquid crystal cell 4. Specifically, the first polarizer 5a is attached to the first surface of the liquid crystal cell 4 through the first adhesive layer 6a composed of an adhesive or an adhesive; and the second surface of the liquid crystal cell 4 is transmitted through the adhesive or The second adhesive layer 6b made of an adhesive is used to attach the second polarizer 5b. Hereinafter, the first and second polarizers 5 a and 5 b may be simply referred to as “polarizer 5”, and the first and second adhesive layers 6 a and 6 b may be collectively referred to as “adhesive layer 6”. In addition, the drawing of the subsequent layer 6 is omitted in FIG. 3.

<Liquid Crystal Cell> As shown in FIG. 2, the liquid crystal cell 4 includes a pair of liquid crystal cell substrates 41 and 41, a spacer 43, and a liquid crystal layer 42. Among the pair of liquid crystal cell substrates 41 and 41, the first liquid crystal cell substrate 41a is located on the first surface side, and the second liquid crystal cell substrate 41b is located on the second surface side. The spacer 43 is a member that maintains a constant distance between the first liquid crystal cell substrate 41a and the second liquid crystal cell substrate 41b. A liquid crystal compound is injected into the space formed by the spacer 43, and a layer composed of the liquid crystal compound is a liquid crystal layer 42. In addition, although not particularly shown, a switching element (for example, a TFT) that controls the photoelectric characteristics of a liquid crystal compound is usually provided on one of the first and second liquid crystal cell substrates 41a and 41b, and the other The substrate will be equipped with color filters. The above-mentioned control means such as a microcomputer is connected to the switching element. The liquid crystal cell substrate 41 is not particularly limited as long as it is excellent in transparency. The liquid crystal cell substrate 41 can be, for example, a transparent glass plate such as soda-lime glass, low-alkali borosilicate glass, or alkali-free aluminum borosilicate glass, or polycarbonate, polymethyl methacrylate, or polyethylene terephthalate. , Epoxy resin and other transparent resin plates.

The liquid crystal compound constituting the liquid crystal layer 42 is not particularly limited, and a suitable liquid crystal compound can be selected from conventionally known liquid crystal compounds in accordance with the liquid crystal alignment mode and liquid crystal display mode of the liquid crystal cell 4 and used. The liquid crystal alignment mode of the liquid crystal cell 4 includes, for example, a vertical alignment (VA) mode, a twisted nematic (TN) mode, a vertical alignment type electrically controlled birefringence (ECB) mode, a horizontal switching (IPS) mode, and optically compensated birefringence ( OCB) mode. The liquid crystal display mode of the liquid crystal cell 4 can be a normally white mode (a mode in which light from the light source 2 penetrates when a voltage is not applied) and a liquid crystal compound in a white state when no voltage is applied to the liquid crystal compound. The liquid crystal compound exhibits a normally black mode with a black display when a voltage is applied (a mode in which light from the light source 2 does not penetrate when a voltage is not applied).

<Polarizer> The polarizer 5 is a member that filters out linearly polarized light having a specific vibration direction from natural light (non-polarized light). As shown in FIG. 3, the polarizer 5 has an absorption axis A in its surface and a transmission axis (not shown) in a direction perpendicular to the absorption axis A. The polarizer 5 has a property of selectively transmitting linearly polarized light having a vibration direction parallel to the extending direction of the transmission axis. Hereinafter, the extension direction of the absorption axis A may be simply referred to as the "absorption axis direction", and the extension direction of the penetration axis may be simply referred to as the "penetration axis direction".

In the present invention, a slightly rectangular polarizer 5 is used. In general, the shape of the polarizer 5 is the same shape as that of the liquid crystal cell 4 and is preferably the same shape and slightly the same size. In this embodiment, a rectangular polarizer 5 having the same shape as the rectangular liquid crystal cell 4 is used. Here, "slightly rectangular" in this specification includes not only strict rectangles (4 right angles formed by the two long sides and two short sides constituting the rectangle), but also includes those within the technically acceptable range of the present invention. Other shapes. Specific other shapes include, for example, a shape in which corners of a rectangle are chamfered, or a shape in which one long side of the rectangle is shorter than the other long side. It is preferable to use a rectangular polarizer 5 as shown in this embodiment.

In the slightly rectangular polarizer 5, the length of the long side to the short side is not particularly limited, and can be set according to the aspect ratio of the screen used in the liquid crystal display device 10 (for example, a television or the like) generally used. For example, the lower limit value of the long side length of the polarizer 5 is 1.2 times its short side length, and preferably 1.5 times, preferably 1.8 times; the upper limit value of its long side length is 8.0 times its short side length. And preferably 5.0 times, preferably 3.0 times. By setting the lower limit value and the upper limit value of the long side length of the polarizer 5 to be in the foregoing range, based on the principle of preventing warpage of the liquid crystal panel 1 of the present invention described later, warpage of the liquid crystal panel 1 can be effectively prevented.

The polarizer 5 used in the present invention is not particularly limited, and any polarizer can be used. The polarizer 5 preferably uses a shrinkage rate (AS) in the absorption axis direction which is larger than a shrinkage rate (TS) in the transmission axis direction. The shrinkage ratio (AS) in the direction of the absorption axis is the size of the unshrinked polarizer and the size of the shrinked polarizer obtained by placing the unshrinked polarizer in a constant temperature room (temperature 60 ° C, humidity 90% RH) for 3 hours. Find it. Specifically, when the maximum length in the absorption axis direction of the non-contracted polarizer is X1, and the maximum length in the absorption axis direction of the contracted polarizer is X2, the shrinkage rate (AS) in the absorption axis direction can be based on the following formula 1 Figure it out. [Mathematical formula 1] AS (%) = {(X1-X2) / X1} × 100 Moreover, the shrinkage rate (TS) in the penetration axis direction is the same as the shrinkage rate (AS) in the absorption axis direction, and it has never contracted. The size of the polarizer is determined from the size of the shrinkable polarizer obtained by placing the non-shrinking polarizer in a constant temperature room (temperature 100 ° C, humidity 80% RH) for 3 hours. Specifically, when the maximum length in the direction of the transmission axis of the unshrinked polarizer is Y1, and the maximum length in the direction of the transmission axis of the shrinked polarizer is Y2, the shrinkage rate (TS) in the direction of the transmission axis can be determined according to the following It can be calculated by the expression 2. [Mathematical formula 2] TS (%) = {(Y1-Y2) / Y1} × 100

The difference (ΔS) between the shrinkage rate (AS) in the absorption axis direction and the shrinkage rate (TS) in the transmission axis direction can be calculated by Equation 3 below. [Mathematical formula 3] ΔS (%) = AS-TS The value of ΔS is not particularly limited, but the lower limit value is usually 1.0%, preferably 2.0%, and preferably 5.0%. The upper limit of ΔS is usually 15.0%, preferably 10.0%, and preferably 8.0%. By setting ΔS in the foregoing range, warpage of the liquid crystal panel 1 can be sufficiently prevented based on the principle of warpage prevention of the liquid crystal panel 1 of the present invention described later. When ΔS exceeds 15.0%, excessive deformation stress is applied to the liquid crystal cell 4, which is not practical.

As shown in FIG. 3, in this embodiment, rectangular first and second polarizers 5a and 5b are used. The first polarizer 5a has an absorption axis A in its longitudinal direction (the extending direction of the rectangular long side), and the first The 2 polarizer 5b has an absorption axis A in its short direction (the extending direction of the rectangular short side). Therefore, in the first polarizer 5a of this embodiment, X1 in the above formula 1 corresponds to the long side length of the unshrinked first polarizer 5a, and X2 corresponds to the long side of the first polarizer 5a after shrinkage. length. In addition, Y1 in the aforementioned formula 2 corresponds to the short-side length of the unshrinked first polarizer 5a, and Y2 corresponds to the short-side length of the first polarizer 5a after shrinking. On the other hand, in the second polarizer 5b of this embodiment, X1 in the above formula 1 corresponds to the short side length of the unshrinked second polarizer 5b, and X2 corresponds to the short length of the second polarizer 5b after shrinkage. Side length. In addition, Y1 in the above formula 2 corresponds to the long side length of the unshrinked second polarizer 5b, and Y2 corresponds to the long side length of the second polarizer 5b after shrinking.

In general, polarizers include polarizers obtained by adsorbing a dichroic substance on a resin film and stretching them (hereinafter referred to as "adsorption polarizers"), and by coating and drying an arbitrary coating surface containing organic materials. There is a big difference between polarizers (hereinafter referred to as "coating-type polarizers") obtained by applying a pigment coating solution. In the present invention, it is preferable to use an adsorption-type polarizer. When an adsorption-type polarizer is used, the aforementioned value of ΔS can be easily satisfied.

The dichroic substance contained in the adsorption-type polarizer is not particularly limited. Examples of the dichroic substance include iodine and organic dyes. As the organic dye, for example, Red BR, Red LR, Red R, Pink LB, Magenta BL, Bordeaux GS, SkyBlue LG, and Lemon can be used. Yellow (LemonYellow), Blue (BR), Blue (2), Navy (RY), Green (LG), Violet (LB), Violet (B), Black (H), Black ( Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct Fast Orange Orange) S, Fast Black. These dichroic substances can be used alone or in combination of two or more. Iodine should be used.

The resin film (resin film capable of adsorbing a dichroic substance) contained in the adsorption-type polarizer is not particularly limited. Any appropriate resin can be used as the resin constituting the resin film. Examples of the resin constituting the resin film include cellulose ester resin, polyester resin, polyether fluorene resin, polyfluorene resin, polycarbonate resin, polyamine resin, polyimide resin, and polyimide resin. Olefin resins, (meth) acrylic resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. As the resin constituting the resin film, at least one selected from the group consisting of a polyvinyl alcohol-based resin, a polyester-based resin, a polystyrene-based resin, and a polyamide-based resin is preferably used, and a polyvinyl alcohol-based resin is preferably used. By using a polyvinyl alcohol-based resin, the aforementioned value of ΔS can be easily satisfied.

Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol and an ethylene-vinyl alcohol copolymer. When a polyvinyl alcohol-based resin is used, the polyvinyl alcohol-based resin can be obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester-based monomer such as vinyl acetate. In terms of the degree of saponification or the degree of polymerization, a polyvinyl alcohol having a high degree of saponification and a high degree of polymerization is preferably used from the viewpoint of good heat resistance and the like. The saponification degree of the polyvinyl alcohol-based resin is not particularly limited. For example, it is preferably 90 mol% to 100 mol%, and particularly preferably 95.0 mol% to 99.9 mol%. By using a polyvinyl alcohol-based resin having such a degree of saponification, it is possible to obtain a polarizer 5 that satisfies the value of the aforementioned ΔS and is excellent in durability. The saponification degree can be determined in accordance with JIS K 6726-1994. The average degree of polymerization of the polyvinyl alcohol-based resin is also not particularly limited. For example, it is preferably 1,000 to 8,000, more preferably 1,200 to 3,600, and particularly preferably 1,500 to 5,000. The average degree of polymerization can be determined in accordance with JIS K 6726-1994.

The resin film containing a polyvinyl alcohol-based resin can be made by dissolving a resin composition containing a polyvinyl alcohol-based resin in an appropriate organic solvent such as water or DMSO, thereby preparing a resin solution, and further forming the resin solution. Film to obtain.

Appropriate additives such as a plasticizer and a surfactant may be blended in the resin constituting the resin film. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. The surfactant may be, for example, a nonionic surfactant. By adding such a plasticizer or a surfactant, a polyvinyl alcohol-based resin having excellent adsorptivity and extensibility of a dichroic substance can be obtained. The amount of the plasticizer and the surfactant to be added is not particularly limited, but it is generally 1 to 10 parts by mass relative to 100 parts by mass of the polyvinyl alcohol-based resin.

The first polarizer 5a and the second polarizer 5b may be the same type or different types. When the first polarizer 5a and the second polarizer 5b are the same type, it means that both the resin and the dichroic substance contained in the first polarizer 5a are the same as the resin and the dichroic substance contained in the second polarizer 5b. The first polarizer 5a and the second polarizer 5b are different from each other, which means that at least one of the resin and dichroic substance contained in the first polarizer 5a and the resin and dichroic substance contained in the second polarizer 5b. Sexual matter is different. In addition, when the resin and the dichroic material are the same and the manufacturing conditions such as the stretching magnification are the same, the first polarizer 5a and the second polarizer 5b are the same except for the absorption axis direction and thickness. The first polarizer 5a and the second polarizer 5b are preferably the same type, and preferably the same except for the direction and thickness of the absorption axis.

In the present invention, as shown in FIG. 3, the first polarizer 5a has an absorption axis A extending in its long direction, and the second polarizer 5b has an absorption axis A extending in its short direction. The first polarizer 5a and the second polarizer 5b are disposed so as to intersect with each other perpendicularly to the extension direction of the absorption axis A. That is, the first polarizer 5a and the second polarizer 5b are placed in a crossed nicols state. Further, in the present invention, the thickness of the second polarizer 5b is larger than the thickness of the first polarizer 5a. Therefore, the present invention can effectively prevent warping of the liquid crystal panel 1. The principle of effectively preventing warpage of the liquid crystal panel 1 by disposing the first and second polarizers 5a and 5b thus disposed in the liquid crystal cell 4 is not clear, but the inventors of the present invention presumed as follows.

FIG. 4 is a plan view showing a laminated body of the first polarizer 5a with an unshrinked rectangle attached to the liquid crystal cell 4. FIG. 5 (a) is a plan view showing the first polarizer 5a as a laminated body after shrinking, and FIG. 5 (b) It is a cross-sectional view of the laminated body after the first polarizer 5 a is contracted in the longitudinal direction (direction parallel to the long sides of the rectangle). The polarizer 5 has a property of contracting mainly in the absorption axis direction. In the present invention, the first polarizer 5a has an absorption axis A extending in the long direction. Therefore, in the shrinking process, the first polarizer 5a mainly faces the center of the long side of the rectangle parallel to the absorption axis direction (pointed arrow in FIG. 4). The direction indicated by the number) shrinks, but hardly shrinks in a direction (short direction) that intersects perpendicularly to the absorption axis direction. In other words, it can be said that the contraction force of the first polarizer 5a in the long direction is larger than that in the short direction. As a result, once the first polarizer 5a is contracted, the liquid crystal cell 4 is strongly pulled in the long direction due to the first polarizer 5a, whereby the laminated body is warped in the long direction as shown in FIG. 5 (b). That is, the planar first polarizer 5a in an uncontracted state causes the liquid crystal cell 4 to be deformed into a U-shaped curved surface in the longitudinal direction due to the contraction. Therefore, when the first polarizer 5a is disposed on the first surface side of the liquid crystal cell 4, the first surface of the liquid crystal cell 4 is applied in the long direction from the first polarizer 5a due to the contraction of the first polarizer 5a. Deformation stress (hereinafter referred to as "first deformation stress") occurs in a U-shaped curved surface.

On the other hand, FIG. 6 shows a plan view of a laminated body of the second polarizer 5b with an unshrinked rectangle attached to the liquid crystal cell 4. FIG. 7 (a) shows a plan view and a diagram of the laminated body of the second polarizer 5b 7 (b) is a cross-sectional view of the second polarizer 5b in the short direction (direction parallel to the short side of the rectangle) of the laminated body after shrinking. In the present invention, the second polarizer 5b has an absorption axis A extending in a short direction. Therefore, in the shrinking process, it will mainly shrink in the direction parallel to the absorption axis direction and the center of the rectangular short side (the direction indicated by the arrow mark in FIG. 6), and it will hardly intersect perpendicularly to the absorption axis direction. Shrink in direction (long direction). In other words, it can be said that the second polarizer 5b has a larger contraction force in the short direction and a longer contraction force in the longer direction. As a result, once the second polarizer 5b is contracted, the liquid crystal cell 4 is strongly pulled in the short direction due to the second polarizer 5b, whereby the laminated body is warped in the short direction as shown in FIG. 7 (b). That is, the flat second polarizer 5b in the uncontracted state causes the liquid crystal cell 4 to be deformed in a short direction to produce a U-shaped curved surface due to the contraction. Therefore, when the second polarizer 5b is disposed on the second surface side of the liquid crystal cell 4, the second surface of the liquid crystal cell 4 may be applied from the second polarizer 5b in the short direction due to the contraction of the second polarizer 5b. Deformation stress (hereinafter referred to as "second deformation stress") occurs in a U-shaped curved surface.

First deformation stress applied to the liquid crystal cell 4 from the first polarizer 5a (stress generating a U-shaped curved surface in the long direction) and second deformation stress applied to the liquid crystal cell 4 from the second polarizer 5b (generated in the short direction) U-shaped curved surface)). Therefore, in the liquid crystal cell 4 in which the first and second polarizers 5a and 5b are provided, the first deformation stress and the second deformation stress are canceled.

The inventors of the present invention believe that the warpage of the liquid crystal panel 1 including the liquid crystal cell 4 can be prevented by offsetting the first deformation stress and the second deformation stress in a good balance inside the liquid crystal cell 4. The result of careful discussion found that the magnitude of the deformation stress was related to the length of the polarizer's absorption axis and the thickness of the polarizer. Specifically, the present inventors have found that the longer the length in the absorption axis direction of the polarizer, the larger the deformation stress, and the shorter the length, the smaller the deformation stress; and the thicker the thickness of the polarizer, the larger the deformation stress. The thinner the smaller the deformation stress. The first polarizer 5a has an absorption axis A in its long direction, and the second polarizer 5b has an absorption axis A in its short direction. Therefore, if the thickness of the second polarizer 5b is the same as or smaller than that of the first polarizer 5a, the first deformation stress generated from the first polarizer 5a may be changed. It is much larger than the second deformation stress generated by the second polarizer 5b. In the liquid crystal cell 4, the first deformation stress cannot be sufficiently cancelled through the second deformation stress, and as a result, the liquid crystal cell 4 is included. The liquid crystal panel 1 is warped. In view of this, in the present invention, since the thickness of the second polarizer 5b is larger than that of the first polarizer 5a, the opposite two lattice deformation stresses (the first deformation stress and the second deformation stress) will be well balanced inside the liquid crystal cell 4. offset. The result is considered to be that the warpage of the liquid crystal panel 1 containing the liquid crystal cell 4 can be effectively prevented.

The thickness of the second polarizer 5b is not particularly limited as long as it is larger than the thickness of the first polarizer 5a. Of course, if the second polarizer 5b is much thicker than the first polarizer 5a, there is a possibility that the two opposite deformation stresses described above cannot be well balanced in the liquid crystal cell 4 to offset. Taking this into consideration, the lower limit value of the ratio (T1 / T2) of the thickness (T1) of the first polarizer 5a to the thickness (T2) of the second polarizer 5b should be 1/15, and preferably 1/10 , 1/5 is better, 1/4 is especially good. The upper limit of the ratio (T1 / T2) is preferably 1/2, more preferably 1 / 2.5, and particularly preferably 1/3. The lower limit of the difference (T2-T1) between the thickness (T2) of the second polarizer 5b and the thickness (T1) of the first polarizer 5a is preferably 2 μm, and preferably 5 μm, more preferably 10 μm, or more. 13 μm is particularly preferred. The upper limit of the difference (T2-T1) is preferably 30 μm, more preferably 25 μm, more preferably 20 μm, and particularly preferably 17 μm. By making the thicknesses of the first polarizer 5a and the second polarizer 5b satisfy the above-mentioned relationship, the two opposite deformation stresses in the liquid crystal panel 1 can be well balanced, and the warpage of the liquid crystal panel 1 can be effectively prevented.

The lower limit value of the thickness of the first polarizer 5a is preferably 2 μm, more preferably 3 μm, more preferably 4 μm, and particularly preferably 5 μm. The upper limit of the thickness of the first polarizer 5a is preferably 20 μm, more preferably 15 μm, more preferably 10 μm, and particularly preferably 8 μm. The lower limit value of the thickness of the second polarizer 5b is preferably 4 μm, more preferably 10 μm, more preferably 15 μm, and particularly preferably 20 μm. The upper limit of the thickness of the second polarizer 5b is preferably 50 μm, more preferably 40 μm, more preferably 30 μm, and particularly preferably 25 μm. If the thicknesses of the first polarizer 5a and the second polarizer 5b are within the above-mentioned range, the two opposite deformation stresses in the liquid crystal panel 1 can be offset in a good balance, and warpage of the liquid crystal panel 1 can be effectively prevented.

The degree of polarization of the polarizer 5 is not particularly limited, but it is preferably 90% or more, more preferably 95% or more, more preferably 96% or more, and particularly preferably 99% or more. The degree of polarization may be adjusted in accordance with the thickness of the first and second polarizers 5a and 5b, for example. By setting the polarization degree within the above range, the liquid crystal display device 10 having high oblique contrast can be obtained. The polarization degree can be measured using a spectrophotometer (manufactured by Murakami Color Technology Research Institute, Ltd., product name "DOT-3"). The individual transmittance of the polarizer 5 is preferably 35% to 45%, and preferably 39% to 42%. By making the unit transmittance within the above range, a liquid crystal display device 10 with high oblique contrast can be obtained. In addition, the monomer transmission rate is the Y value based on the three-stimulus value of the 2-degree field of view of J1S Z 8701-1995.

<Adhesive Layer> In this embodiment, as shown in FIG. 2, the first polarizer 5a is attached to the first surface of the liquid crystal cell 4 through the first adhesive layer 6a, and the second polarizer 5b is transmitted through the second adhesive layer. 6b is attached to the second surface of the liquid crystal cell 4. In the present invention, as described above, the first deformation stress generated by the shrinkage of the first polarizer 5a is effectively balanced by the second deformation stress generated by the shrinkage of the second polarizer 5b, thereby being effective. Warping of the liquid crystal panel 1 is prevented. Therefore, the first deformation stress caused by the shrinkage of the first polarizer 5a should be difficult to be absorbed by the first adhesive layer 6a. Similarly, the second deformation stress produced by the shrinkage of the second polarizer 5b should be difficult to be absorbed by the second Layer 6b then absorbs. That is, the first and second adhesive layers 6a and 6b are preferably hard (low flexibility).

Specifically, the hardness of the adhesive layer 6 is 30 to 90, preferably 50 to 90, and preferably 70 to 90. The hardness of the adhesive layer 6 is a value measured in accordance with a type A durometer described in JIS K6253 (hardness test method for vulcanized rubber and thermoplastic rubber). The resin component of the adhesive or the adhesive constituting the adhesive layer 6 is not particularly limited, and can be appropriately selected in consideration of the compatibility with the resin film contained in the polarizer 5. Examples of the resin component of the adhesive or the adhesive include acrylic resins, silicone resins, polyester resins, polyamide resins, polyvinyl alcohol resins, epoxy resins, fluorine resins, and mixtures thereof. Wait. The resin component of the adhesive or the adhesive is preferably the same as the resin film contained in the polarizer 5. This is because the adhesive force between the polarizer 5 and the adhesive layer 6 becomes stronger, and the polarizer 5 becomes difficult to peel off from the liquid crystal cell 4. For example, when the polarizer 5 containing a polyvinyl alcohol resin is next, it is preferable to use the adhesive layer 6 containing a polyvinyl alcohol resin.

<The manufacturing method of a polarizer> The manufacturing method of the polarizer of this invention is demonstrated using the case where an adsorption | polarization type polarizer is used as an example. The polarizer of the present invention can be produced through, for example, a swelling step, an adsorption step, an extension step, a crosslinking step, and a washing and drying step. Hereinafter, each step will be briefly described.

(Swelling step) The swelling step is a step of swelling a resin film to which a dichroic substance is adsorbed. As the constituent material of the resin film, the above can be used. The resin film is usually in an unstretched state in the swelling step. Generally, a resin film is wound into a roll shape, and a rolled-up resin film is introduced into a swelling bath by a conveyance roller. The swelling bath is filled with swelling fluid. Swelling fluids usually use water. The liquid temperature of the swelling bath is usually adjusted to 20-50 ° C, and preferably 30-40 ° C. The time for which the resin film is immersed in the swelling bath is generally 1 to 7 minutes. The swelling step is performed before the adsorption step, thereby removing the dirt on the surface of the resin film and reducing the uneven adsorption of the dichroic material.

(Adsorption step) The adsorption step is a step of adsorbing a dichroic substance to the swollen resin film. The swollen resin film is drawn into the adsorption bath after being pulled out from the swell bath. The adsorption bath is filled with a dyeing solution in which a dichroic substance is dissolved in a solvent. The solvent is generally water, but an organic solvent compatible with water may be added. In the adsorption bath, the concentration of the dichroic substance is not particularly limited, but is preferably 0.0001% to 10% by mass, and more preferably 0.001% to 7% by mass.

As the dichroic substance, those exemplified above can be used. When the dichroic substance is iodine, iodide may be added to the dyeing solution. Examples of the iodide include potassium iodide and lithium iodide. The ratio of iodide to iodide (mass ratio) of the added iodide should be 1: 5 ~ 1: 100. The immersion time of the resin film in the adsorption bath is not particularly limited, and it is preferably 20 seconds to 1,800 seconds. The liquid temperature of the adsorption bath is preferably 20 ° C to 80 ° C, and more preferably 40 ° C to 60 ° C. If the temperature of the adsorption bath is too high, the film may melt; if it is too low, the adsorptivity of the dichroic substance to the resin film may decrease.

(Stretching step) The stretching step is a step of subjecting the resin film to a stretching treatment. The stretching process is usually a uniaxial stretching process. The stretching treatment may be performed from the swelling step to the adsorption step, or during the swelling step and / or the adsorption step. The stretching process can be performed by, for example, changing the rotation speed of the plurality of conveying rollers that send out the resin film to facilitate implementation. With the stretching treatment, the resin film should be stretched to 2 to 7 times its original length, preferably 2.5 to 6 times, and more preferably 3 to 5 times. In addition, the original length of the resin film is based on the unstretched resin film before entering the swelling step. If the extension magnification is less than 2 times, it may not only be difficult to obtain a polarizer with a high degree of polarization, but it may be difficult to obtain a polarizer that satisfies the above-mentioned ΔS range. On the other hand, if the stretching ratio exceeds 7 times, the film may be broken. Through the stretching step, the dichroic substance adsorbed on the resin film is oriented in the stretching direction, and as a result, a long polarizer having an absorption axis A in the stretching direction can be obtained. In the case where a plurality of stretching treatments are performed, the range of the stretching magnification means the total stretching magnification.

(Crosslinking step) The crosslinking step is a step of bringing a stretched resin film (that is, a long polarizer) in contact with a dichroic substance into contact with the crosslinking agent. The cross-linking step can be performed by introducing a long polarizer into a cross-linking bath. The crosslinking bath is filled with a crosslinking solution in which a crosslinking agent is dissolved in a solvent. As the solvent, for example, water may be used, and further, an organic solvent compatible with water may be added. The concentration of the crosslinking agent in the solution is not particularly limited, but is preferably 0.01% by mass to 20% by mass, and more preferably 0.1% by mass to 10% by mass. If the concentration of the crosslinking agent is less than 0.01%, there is a possibility that a sufficient crosslinking effect cannot be obtained. On the other hand, even if the concentration of the cross-linking agent exceeds 20%, the cross-linking effect is almost unchanged, so the effect is not good in terms of cost. Examples of the crosslinking agent include boron compounds such as boric acid and borax; glyoxal; and glutaraldehyde. These can be used individually by 1 type or in combination of 2 or more types. Through the cross-linking step, the orientation of the dichroic substance adsorbed to the resin film can be stabilized, and a long polarizer having more excellent water resistance can be obtained.

(Washing and Drying Step) The washing and drying step is a step of removing excess cross-linking solution from the surface of the long polarizer obtained through the cross-linking step. The washing can be performed by pulling the long polarizer out of the cross-linking bath and then introducing it into the washing bath. The washing bath is filled with washing solution. The cleaning solution is usually water. After removing the excess cross-linking solution with a washing bath, the polarizer is pulled out from the washing bath and introduced into a drying device. The polarizer is heated and dried by a drying device, thereby obtaining a long polarizer without excessive cross-linking agent adhered to the surface. In addition, the drying temperature of the heating device is usually 20 to 50 ° C, and the drying time is 1 to 10 minutes. If the drying temperature of the heating device exceeds 50 ° C., the polarizer may shrink before the polarizer is placed on the liquid crystal panel 1. The same applies when the drying time exceeds 10 minutes. The polarizer of the present invention can be obtained by cutting the long polarizer in the overwashing and drying step to a specific size.

The liquid crystal panel 1 of the present invention is provided with a first polarizer 5a on the first surface side of the liquid crystal cell 4, and a second polarizer 5b having a thickness greater than that of the first polarizer 5a on the second surface side of the liquid crystal cell 4. The first polarizer 5a is a slightly rectangular polarizer 5 having an absorption axis A in its long direction, and the second polarizer 5b is a slightly rectangular polarizer 5 having an absorption axis A in its short direction. The two polarizers 5a and 5b are arranged in a crossed nicols state. Therefore, in the liquid crystal cell 4, the first deformation stress generated by the shrinkage of the first polarizer 5a is offset by the second deformation stress generated by the shrinkage of the second polarizer 5b, and as a result, it can be effectively prevented Warping of the liquid crystal panel 1.

In addition, when the liquid crystal panel 1 of this embodiment is mounted on the liquid crystal display device 10, the first surface side of the liquid crystal panel 1 can be arranged as the visible surface side of the liquid crystal display device 10 (that is, the first polarizer 5a is positioned at The visible surface side and the second polarizer 5b are located on the reverse visible surface side), and the second surface side of the liquid crystal panel 1 may be arranged as the visible surface side of the liquid crystal display device 10 (that is, the second polarizer 5b is located on the visible surface) Side and the first polarizer 5a is located on the retro-viewable surface side). In any case, warpage of the liquid crystal panel 1 can be effectively prevented.

In the liquid crystal panel 1 according to the first embodiment, although the polarizer 5 is not laminated with other layers, a protective film or the like may be laminated on the polarizer 5 in the present invention. Hereinafter, a liquid crystal panel 1 according to the second to fourth embodiments of the present invention will be described with respect to a polarizing plate having a polarizer 5 and a protective film, and the aforementioned polarizing plate being provided in a liquid crystal cell 4. The liquid crystal panel 1 according to the second to fourth embodiments will mainly be described in terms of differences from the first embodiment, and the common points will be appropriately omitted. In addition, in FIGS. 8 to 10, in order to make the layer structure of the liquid crystal panel 1 easy to understand, the adhesive layer between the layers is omitted, and the liquid crystal cell 4 is also briefly drawn. The adhesive layers used in the second to fourth embodiments are not particularly limited, and the same ones as the first and second adhesive layers 6a and 6b of the first embodiment can be used.

[About the liquid crystal panel of the second embodiment] As shown in FIG. 8, regarding the liquid crystal panel 1 of the second embodiment, the first polarizing plate 8 a having the first polarizer 5 a and the first protective film 7 a is provided on the liquid crystal cell 4. The second polarizing plate 8 b on the first surface side and having the second polarizer 5 b and the second protective film 7 b is provided on the second surface side of the liquid crystal cell 4. For example, the first polarizing plate 8a can be produced by attaching the first protective film 7a through the adhesive layer on the first surface side of the first polarizing member 5a; the second polarizing plate 8b can be produced by attaching the second polarizing member 5b On the second surface side, a second protective film 7b is produced through an adhesive layer. Hereinafter, the first and second protective films 7a and 7b may be collectively referred to simply as "protective film 7", and the first and second polarizing plates 8a and 8b may be collectively referred to as "polarizing plate 8".

The protective film 7 is not particularly limited, and it is preferable to use a flexible film that is excellent in mechanical strength and does not excessively hinder the shrinkage of the first and second polarizers 5 a and 5 b. This is because the present invention uses the two opposite deformation stresses generated by the shrinkage of the first and second polarizers 5a and 5b to prevent warping of the liquid crystal panel 1. In this case, if the protective film 7 If the shrinkage of the first and second polarizers 5 a and 5 b is excessively hindered, the opposite two deformation stresses cannot be offset inside the liquid crystal cell 4, and there is a possibility of warping the liquid crystal panel 1.

The protective film 7 is preferably transparent. The so-called "transparent" means that it has the property of transmitting visible light with a wavelength of 360 nm to 830 nm. Transparency includes a case in which visible light is not substantially absorbed and light of all wavelengths in the visible light range is transmitted (colorless and transparent), and a case in which light of a part of wavelengths in the visible light range is absorbed and light outside the wavelength is transmitted (colored and transparent). The protective film 7 is preferably colorless and transparent. If the protective film 7 is colorless and transparent, it is possible to prevent light banding (optical banding) of light emitted from the liquid crystal display device 10. Specifically, the total light transmittance of the protective film 7 is 50% or more, preferably 70% or more, and more preferably 90% or more. The total light transmittance is a value measured based on JIS K7375.

The protective film 7 is preferably moisture-proof. Specifically, the moisture permeability of the protective film 7 is usually 150g / m ² / 24h or less, and is suitably 120g / m ² / 24h or less, to 100g / m ² / 24h or less is preferable. If the moisture permeability of the protective film 7 is in such a range, it is possible to effectively prevent the liquid crystal cell 4 from being deteriorated due to moisture. In addition, the water vapor transmission rate is based on the JIS Z 0208 water vapor transmission test (cup method). The water vapor content (g) of a sample with an area of 1 m ² in 24 hours is measured in an environment with a temperature of 40 ° C and a humidity of 92% RH. The value obtained.

The resin constituting the protective film 7 is not particularly limited, and examples thereof include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; celluloses such as diacetyl cellulose and triethyl cellulose (Meth) acrylic resins such as polymethyl methacrylate; styrene resins such as polystyrene, acrylonitrile · styrene copolymer (AS resin); polycarbonate resins; vinyl chloride resins; Ammonium resins such as nylon and aromatic polyamines; ammonium resins; ammonium resins; aryl ester resins; epoxy resins and mixtures thereof. The resin constituting the protective film 7 is preferably at least one selected from a (meth) acrylic resin, a polyester resin, and a styrene resin, and a (meth) acrylic resin is preferably used. The (meth) acrylic resin is easy to satisfy the above-mentioned moisture permeability and total light transmittance in addition to being high in mechanical strength and relatively soft. Therefore, it is suitable as a material for forming the protective film 7.

Examples of the (meth) acrylic resin include poly (meth) acrylates such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic copolymer, and methyl methacrylate- (meth) acrylic acid. Ester copolymer, methyl methacrylate-acrylate- (meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer, and the like. The weight average molecular weight of the (meth) acrylic resin is preferably 10,000 to 500,000. If the weight average molecular weight is too small, there is a possibility that the mechanical strength when the film is made into a film may be insufficient. On the other hand, if the weight average molecular weight is too large, the viscosity at the time of melt extrusion will increase, the moldability will decrease, and the productivity of the molded product may decrease.

In order to obtain the desired physical properties described above, a (meth) acrylic resin having a glutariminium unit is preferably used as the (meth) acrylic resin. A (meth) acrylic resin of a methyl acrylate unit is preferable. When a (meth) acrylic resin having a glutariminium unit and a methyl methacrylate unit is used, the hydrazone imidization rate is preferably 2.5% to 5.0%, and the acid value is preferably 0.1mmol / g to 0.5mmol. / g, and preferably contains less than 1% by weight of acrylate units.

The thickness of the protective film 7 is not particularly limited, but is usually 2 μm to 100 μm, and preferably 2 μm to 50 μm, preferably 2 μm to 30 μm, and more preferably 2 μm to 10 μm. When the protective film 7 is in such a thickness range, the first and second polarizers 5a and 5b can be protected without excessively hindering the shrinkage of the first and second polarizers 5a and 5b.

In this embodiment, the first protective film 7a is laminated on the first polarizer 5a (that is, the first polarizer 5a is used as the substrate by the first protective film 7a). Therefore, compared with the first embodiment, the first The polarizer 5a becomes slightly difficult to shrink. As a result, the first deformation stress smaller than the first deformation stress generated in the first embodiment is applied to the liquid crystal cell 4. However, in this embodiment, the second protective film 7b is also laminated on the second polarizer 5b. Therefore, the second deformation stress due to the deformation of the second polarizer 5b in this embodiment is also larger than that in the first embodiment. The second deformation stress caused by the deformation of the second polarizer 5b is even smaller. Therefore, in this embodiment, the same principle as in the first embodiment is also adopted, and the two opposite deformation stresses (the first deformation stress and the second deformation stress) are well balanced in the liquid crystal cell 4 and the result is It is possible to effectively prevent warping of the liquid crystal panel 1 containing the liquid crystal cell 4.

[About the liquid crystal panel of the third embodiment] In the liquid crystal panel 1 of the third embodiment shown in FIG. 9, a polarizing plate 8 is provided only on the first surface side or the second surface side of the liquid crystal cell 4. Specifically, in FIG. 9 (a), a first polarizing plate 8 a having a first polarizer 5 a and a first protective film 7 a is provided only on the first surface side of the liquid crystal cell 4, and on the second surface of the liquid crystal cell 4 A second polarizer 5b is provided on the side. In FIG. 9 (b), a second polarizing plate 8 b having a second polarizer 5 b and a second protective film 7 b is provided only on the second surface side of the liquid crystal cell 4, and a first polarizer is provided on the first surface side of the liquid crystal cell 4. Polarizer 5a. The third embodiment can be used, for example, when the warpage of the liquid crystal panel 1 of the first embodiment used for a long period of time is to be corrected.

Specifically, although the warpage of the liquid crystal panel 1 can be effectively prevented by using the liquid crystal panel 1 of the first embodiment, there is a possibility that the liquid crystal panel 1 may warp due to the long-term use of the liquid crystal display device 10. This is considered to be because the balance between the first deformation stress and the second deformation stress 2 was slightly broken due to the long-term use of the liquid crystal display device 10. In such a case, it is practically impossible to exchange only the polarizer 5 of the liquid crystal panel 1. This is because the polarizer 5 is attached to the liquid crystal cell 4 through the adhesive layer.

Here, when the liquid crystal panel 1 is formed in a U-shaped curved surface due to the long-term use of the liquid crystal display device 10, the first deformation stress is considered to be much larger than the second deformation stress. Therefore, as shown in FIG. 9 (a), the first polarizing plate 8a is formed by forming the first protective film 7a on the first area layer of the first polarizer 5a, thereby reducing the first deformation stress. Thereby, it can be adjusted again so that the 1st deformation stress can be offset in a good balance through the 2nd deformation stress. On the other hand, when the liquid crystal panel 1 is formed into a U-shaped curved surface due to the long-term use of the liquid crystal display device 10, the first deformation stress becomes smaller than the second deformation stress. a lot of. Therefore, as shown in FIG. 9 (b), the second polarizing plate 8b is formed by forming the second polarizing film 8b only on the second area layer of the second polarizer 5b, thereby reducing the second deformation stress. Thereby, it can be adjusted again so that the 1st deformation stress can be offset in a good balance through the 2nd deformation stress.

The protective film 7 used in this embodiment can be the same as the second embodiment described above. Of course, this embodiment actively aims to change the first deformation stress or the second deformation stress, so the thickness of the protective film 7 should be larger than the value exemplified in the second embodiment. Specifically, the thickness of the protective film 7 is not particularly limited, but is usually 100 μm to 500 μm, preferably 100 μm to 300 μm, and preferably 100 μm to 200 μm.

[About Liquid Crystal Panel of Fourth Embodiment] The liquid crystal panel 1 of the fourth embodiment shown in FIG. 10 is a polarizing plate 8 having protective films 7 on both sides of a polarizer 5. The polarizing plates 8 and 8 are respectively provided on the first surface side and the second surface side of the liquid crystal cell 4. The first polarizing plate 8a provided on the first surface side of the liquid crystal cell 4 includes a first polarizer 5a, a first protective film 7a laminated on the first surface of the first polarizer 5a, and a second polarizer 5a laminated on the second surface of the first polarizer 5a. 3rd protective film 7c. The second polarizing plate 8b provided on the second surface side of the liquid crystal cell 4 includes a second polarizer 5b, a second protective film 7b laminated on the first surface of the second polarizer 5b, and a second polarizer 5b laminated on the second polarizer 5b. Fourth protective film 7d on both sides. This embodiment further improves the liquid crystal panel 1 according to the second embodiment. In this embodiment, since the polarizing plate 8 having two protective films 7 and 7 is used, the liquid crystal cell 4 and the polarizer 5 can be more reliably protected.

The third and fourth protective films 7c and 7d may be films having substantially optical isotropy, or may be retardation films. The term “the protective film 7 has substantially optical isotropy” includes not only the case where the inflection ratio 楕 of the protective film 7 is nx = nz = ny, but also the case where nx ≒ nz ≒ ny. Specifically, the absolute value of the in-plane birefringence Δnxy (nx-ny) and the absolute value of the birefringence Δnxz (nx-nz) in the thickness direction of the protective film 7 are preferably 0.0005 or less, and preferably 0.0001 or less It is better to be 0.00005 or less. In this specification, "nx" means the refractive index in the direction (X-axis direction) where the refractive index of the object (herein, the protective film 7) becomes the maximum at 23 ° C and a wavelength of 590 nm, The aforementioned "ny" indicates a refractive index in a direction (Y-axis direction) in which the X-axis direction intersects perpendicularly in the same plane, and the "nz" indicates a refractive index in a direction (thickness direction) in which the X-axis direction and the Y-axis direction intersect perpendicularly. Refractive index. As the third and fourth protective films 7c and 7d having optical isotropy, the same films as the protective film 7 of the second embodiment can be used. In view of excellent optical isotropy, a film containing a (meth) acrylic resin is preferably used.

By using a retardation film as the third and fourth protective films 7c and 7d, the display characteristics (for example, oblique contrast) of the liquid crystal display device 10 can be improved. Moreover, a retardation film is a transparent film which has retardation in the plane and / or thickness direction. The retardation value of the retardation film in the plane and / or thickness direction is preferably 10 nm to 100, and more preferably 30 nm to 80 nm. The in-plane retardation value is a value obtained by in-plane birefringence (Δnxy) by Δnxy × d (nm), and the thickness direction retardation value is obtained by {(nx ＋ ny) / 2} -nz) × d (nm). d is the thickness of the retardation film. The resin constituting the retardation film is not particularly limited, and examples thereof include polyimide-based resins, polyester-based resins, norbornene-based resins, cellulose-based resins, and mixtures thereof. By forming the resin into a sheet, a retardation film can be obtained.

The liquid crystal panel 1 of the present invention is not limited to the specific configuration shown in the first to fourth embodiments, and the design can be appropriately changed within the intended scope of the present invention. For example, a polarizing plate in which two or more protective films 7 are laminated on the first and second polarizers 5a, 5b, or a first polarizing plate 8a in which a first protective film 7 is laminated on the first polarizer 5a, and The second polarizer 5b is a second polarizing plate 8b in which two or more protective films 7 are laminated.

[Application of liquid crystal panel] The liquid crystal panel of the present invention can be used in any liquid crystal display device. Examples of liquid crystal display devices include OA devices such as computer monitors, notebook computers, and smart phones; portable devices such as digital cameras and portable game consoles; home appliances such as video recorders, televisions, and microwave ovens; back monitors, On-vehicle equipment such as car navigation and car audio; display equipment such as store displays; security equipment such as monitoring displays; medical equipment such as nursing displays and medical displays. The liquid crystal display device equipped with the liquid crystal panel of the present invention is difficult to cause the liquid crystal panel to warp due to temperature changes during use of the liquid crystal display device, and as a result, it is difficult to cause problems such as light leakage and display unevenness.

In the present invention, the first and second polarizers 5a and 5b can be used as a set of polarizers. This set of polarizers can also be applied to a dimming object. This dimming target means something other than the above-mentioned liquid crystal cell 4. That is, the first polarizer 5a may be provided on the first surface side of the light-adjusting object other than the liquid crystal cell 4 and the second polarizer 5b may be provided on the second surface side thereof, thereby forming an optical laminated layer other than the liquid crystal panel. body. In this way, the optical laminated body can also use the same principle as the liquid crystal panel of the present invention to effectively prevent warping. Examples of the dimming object other than the liquid crystal cell 4 include window glass and the like. [Example]

Hereinafter, the present invention will be described in detail with examples and comparative examples. The present invention is not limited to the following examples. The methods for measuring the amount of warpage change used in the examples and comparative examples, and the various films used are as follows.

[Measurement of the amount of warpage change] For the optical laminates produced in the examples and comparative examples, the upper polarizing plate was oriented toward the sky side and the lower surface of the lower polarizing plate was oriented toward the ground side. The height difference D1 (mm) (see FIG. 11) from the ground part (lowest part) to the part closest to the sky (upper part), and this height difference D1 is made into "the initial warpage amount". In addition, the measurement of the height difference D1 is performed in the air and the optical laminate is as close as possible to parallel to the horizontal plane (the same is true for the height difference D2 described later). Thereafter, the optical laminate was placed in a heating container (manufactured by ESPEC Co., Ltd .: product name "Low Temperature Constant Temperature and Humidity") adjusted to a temperature of 60 ° C and 90% RH, and left for 48 hours. After taking out the optical laminate from the heating container, the height difference D2 (mm) between the lowermost portion and the uppermost portion was measured in the same manner as before the heating container was placed, and the height difference D2 was set as the "warpage amount after heating". The absolute value of the difference (D2-D1) between the warpage amount (D2) and the initial warpage amount (D1) after heating was evaluated as the "warpage change amount" of the optical laminate. If the warpage change amount is larger, it means that the warpage of the optical laminate is larger before and after heating; if the warpage change amount is smaller, it means that the optical laminate does not warp due to heating.

[Polarizer and protective film used when producing optical laminated body] The polarizer and protective film constituting the optical laminated body produced in Examples and Comparative Examples were obtained by the following production method. In addition, all the polarizers and protective films used in the examples and comparative examples were cut into a rectangle having a size of 225 mm in length × 400 mm in width.

(Polarizer) <Polarizer A> An amorphous polyethylene terephthalate (A-PET) resin was extruded by a T-die method at a molding temperature of 270 ° C to produce a substrate having a thickness of 200 μm. On this substrate, an aqueous solution (solid concentration: 10%) of a polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: product name "Gohsenol NH-18") was applied and dried to prepare a 10-μm-thick The coating film is dried, and a laminated body of the substrate and the dried coating film is obtained. Using a roll-to-roll stretching machine, the laminate was stretched 1.8 times in the longitudinal direction at 100 ° C, and then the laminate was sequentially immersed in 4 baths under the conditions shown in [1] to [4] while conveying the laminate. And swelling, adsorption, crosslinking and washing of the dried coating film are performed. In addition, in the cross-linking bath, stretching is performed so that the total stretching ratio of the laminate in the longitudinal direction becomes 6 times. [1] Swelling bath: immersed in pure water at 28 ° C for 120 seconds [2] Adsorption bath: immersed in an aqueous solution at 30 ° C for 60 seconds, the aqueous solution is 100 parts by weight of water, contains 1 part by weight of iodine, and 10 weight by potassium iodide Part [3] Cross-linking bath: immersed in an aqueous solution at 60 ° C. for 300 seconds. The aqueous solution is 100 parts by weight of water and contains 7.5 parts by weight of boric acid. [4] Washing bath: After soaking in pure water for 10 seconds, The A-PET resin substrate was peeled off to obtain a dry coating film (polarizer) having a thickness of 5 μm dyed with iodine. The obtained polarizer was cut into a rectangular shape to obtain an adsorption-type polarizer A having an absorption axis in the lateral direction (long direction). <Polarizer B> A polyvinyl alcohol-based resin film ((strand) made by Kuraray: product name "VF-PE-A ♯6000") was adsorbed with iodine to a thickness of 60 μm, and was extended 6 times to produce a 22 μm-thick film. Polarizer. This polarizer was cut into a rectangle to obtain an absorption-type polarizer B having an absorption axis in the longitudinal direction. <Polarizer C> Polyvinyl alcohol-based resin film ((strand) made by Kuraray: product name "VF-PS-N ♯4500") having a thickness of 45 μm was adsorbed on iodine, and extended to 6 times, thereby producing a 18 μm thick Polarizer. This polarizer was cut into a rectangular shape to obtain an adsorption-type polarizer C having an absorption axis in the longitudinal direction (short direction). <Polarizer D> A polarizer having a thickness of 22 μm was obtained in the same manner as the method of manufacturing the polarizer B. Then, the polarizer was cut into rectangles to obtain an adsorption-type polarizer D having an absorption axis in the lateral direction. <Polarizer E> A polarizer having a thickness of 5 μm was obtained in the same manner as the method of manufacturing the polarizer A. Then, the polarizer was cut into rectangles to obtain an adsorption-type polarizer E having an absorption axis in the longitudinal direction.

(Protective film) <Protective film A> Acrylic resin film (manufactured by Toyo Kohan Co., Ltd .: product name "HX-40UC"). The thickness is 40 μm. <Protective film B> Acrylic resin film (manufactured by Toyo Kohan Co., Ltd .: product name "HX-40NE"). The thickness is 40 μm.

[Adhesives used in the production of optical laminates] In the examples and comparative examples, when the polarizers and protective films listed above were laminated, an active energy ray hardening type adhesive was used (Japan Synthetic Chemical Industry Co., Ltd. ) System: product name "Z200"). The thickness of each of the adhesive layers formed using the active energy ray-curable adhesive was 0.7 μm. When the upper polarizing plate and the lower polarizing plate were bonded to a glass plate, a pressure-sensitive adhesive (an acrylic adhesive made by Nitto Denko Corporation) was used. The thickness of each of the adhesive layers formed using the pressure-sensitive adhesive was 23 μm.

[Example 1] A protective film B, a polarizer A, and a protective film A were laminated in this order from the bottom, and then an anti-glare treatment was performed on the upper surface of the protective film A to produce an upper polarizing plate. The upper polarizing plate is expected to be a laminated body provided on the first surface side of the liquid crystal cell. Next, a protective film A, a polarizer B, and a protective film B are laminated in this order from below to produce a lower polarizing plate. The lower polarizing plate is expected to be a laminated body provided on the second surface side of the liquid crystal cell. Continue to use a pressure-sensitive adhesive on the top of the lower polarizing plate (upper surface of the protective film B) to laminate a glass plate (made by Songlang Glass Industry Co., Ltd.) with a length of 245 mm x 420 mm and a thickness of 0.55 mm. The lower surface of the upper polarizing plate of the upper area layer (the lower surface of the protective film B) was used to produce an optical laminate. In the obtained optical laminated body, the absorption axis extension direction of the polarizer A included in the upper polarizer and the polarizer B included in the lower polarizer intersect perpendicularly. The amount of warpage change was calculated for the fabricated optical laminate in accordance with the above-described method for measuring the amount of warpage change. The results are shown in Table 1 below.

[Example 2] A protective film B, a polarizer A, and a protective film A were laminated in this order from the bottom, and then an anti-glare treatment was performed on the upper surface of the protective film A to produce an upper polarizing plate. The upper polarizing plate is expected to be a laminated body provided on the first surface side of the liquid crystal cell. Next, a protective film A, a polarizer C, and a protective film B are laminated in this order from below to produce a lower polarizing plate. The lower polarizing plate is expected to be a laminated body provided on the second surface side of the liquid crystal cell. Continue to use a pressure-sensitive adhesive on the top of the lower polarizing plate (upper surface of the protective film B) to laminate a glass plate (made by Songlang Glass Industry Co., Ltd.) with a length of 245 mm x 420 mm and a thickness of 0.55 mm. The lower surface of the upper polarizing plate of the upper area layer (the lower surface of the protective film B) was used to produce an optical laminate. In the obtained optical laminated body, the absorption axis extension direction of the polarizer A contained in the upper polarizer and the polarizer C contained in the lower polarizer perpendicularly intersect each other. The amount of warpage change was calculated for the fabricated optical laminate in accordance with the above-described method for measuring the amount of warpage change. The results are shown in Table 1 below.

[Comparative Example 1] A protective film B, a polarizer D, and a protective film A were laminated in this order from the bottom, and then an anti-glare treatment was performed on the upper surface of the protective film A to produce an upper polarizing plate. The upper polarizing plate is expected to be a laminated body provided on the first surface side of the liquid crystal cell. Next, a protective film A, a polarizer E, and a protective film B are laminated in this order from below to produce a lower polarizing plate. The lower polarizing plate is expected to be a laminated body provided on the second surface side of the liquid crystal cell. Continue to use a pressure-sensitive adhesive on the top of the lower polarizing plate (upper surface of the protective film B) to laminate a glass plate (made by Songlang Glass Industry Co., Ltd.) with a length of 245 mm x 420 mm and a thickness of 0.55 mm. The lower surface of the upper polarizing plate of the upper area layer (the lower surface of the protective film B) was used to produce an optical laminate. In the obtained optical laminated body, the polarizing member D contained in the upper polarizing plate and the polarizing member E contained in the lower polarizing plate perpendicularly intersect each other in the absorption axis extension direction. The amount of warpage change was calculated for the fabricated optical laminate in accordance with the above-described method for measuring the amount of warpage change. The results are shown in Table 1 below.

[Comparative Example 2] A protective film B, a polarizer A, and a protective film A were laminated in this order from the bottom, and then an anti-glare treatment was performed on the upper surface of the protective film A to produce an upper polarizing plate. The upper polarizing plate is expected to be a laminated body provided on the first surface side of the liquid crystal cell. Next, a protective film A, a polarizer E, and a protective film B are laminated in this order from below to produce a lower polarizing plate. The lower polarizing plate is expected to be a laminated body provided on the second surface side of the liquid crystal cell. Continue to use a pressure-sensitive adhesive on the top of the lower polarizing plate (upper surface of the protective film B) to laminate a glass plate (made by Songlang Glass Industry Co., Ltd.) with a length of 245 mm x 420 mm and a thickness of 0.55 mm. The lower surface of the upper polarizing plate of the upper area layer (the lower surface of the protective film B) was used to produce an optical laminate. In the obtained optical laminated body, the absorption axis extension direction of the polarizer A contained in the upper polarizer and the polarizer E contained in the lower polarizer perpendicularly intersect each other. The amount of warpage change was calculated for the fabricated optical laminate in accordance with the above-described method for measuring the amount of warpage change. The results are shown in Table 1 below.

[Table 1]

[Evaluation] In Examples 1 and 2, the thickness of the polarizer of the lower polarizer was larger than the thickness of the polarizer of the upper polarizer. Therefore, the deformation stress due to the shrinkage of the polarizer of the upper polarizer and the shrinkage stress due to the shrinkage of the polarizer of the lower polarizer can be well balanced in the glass plate, so that the warpage of the optical laminate can be fully prevented song. On the other hand, in Comparative Example 1, the thickness of the polarizer of the upper polarizer is greater than the thickness of the polarizer of the lower polarizer; in Comparative Example 2, the thickness of the polarizer of the upper polarizer and the polarizer of the lower polarizer The thickness is the same. Therefore, the deformation stress due to the shrinkage of the polarizer of the upper polarizer and the shrinkage stress due to the shrinkage of the polarizer of the lower polarizer cannot be fully offset within the glass plate, and the warpage of the optical laminate cannot be fully prevented. . In addition, the protective films used in the examples and comparative examples of the present case hardly shrink even in a high-temperature and constant-humidity environment, and thus hardly affect the warpage of the optical laminate.

10‧‧‧ Liquid crystal display device

1‧‧‧ LCD panel

2‧‧‧ light source

3‧‧‧ border

4‧‧‧ LCD unit

5a (5) ‧‧‧The first polarizer (polarizer)

5b (5) ‧‧‧The second polarizer (polarizer)

6‧‧‧ Adjacent layer

6a‧‧‧The first adhering layer

6b‧‧‧Second Adjacent Layer

7‧‧‧ protective film

7a‧‧‧The first protective film

7b‧‧‧Second protective film

7c‧‧‧3rd protective film

7d‧‧‧4th protective film

8‧‧‧ polarizing plate

8a‧‧‧1st polarizer

8b‧‧‧ 2nd polarizer

41a (41) ‧‧‧The first liquid crystal cell substrate (liquid crystal cell substrate)

41b (41) ‧‧‧Second liquid crystal cell substrate (liquid crystal cell substrate)

42‧‧‧LCD layer

43‧‧‧ spacer

A‧‧‧ Absorption shaft

FIG. 1 is a schematic cross-sectional view showing an embodiment of a liquid crystal display device of the present invention. Fig. 2 is a schematic cross-sectional view showing a liquid crystal panel according to the first embodiment. FIG. 3 is a reference exploded perspective view showing an arrangement state of each layer of the same liquid crystal panel. FIG. 4 is a plan view showing an unshrinkable laminated body having a first polarizer. Fig. 5: (a) is a plan view showing a laminated body after the first polarizer is shrunk; (b) is a cross-sectional view of the same laminated body cut along the Vb-Vb line. FIG. 6 is a plan view showing an unshrinkable laminated body having a second polarizer. Fig. 7: (a) is a plan view showing a laminated body after the second polarizer is shrunk; (b) is a cross-sectional view of the same laminated body cut along the line VIIb-VIIb. Fig. 8 is a schematic sectional view showing a liquid crystal panel according to a second embodiment. 9 (a) is a schematic cross-sectional view showing an example of a liquid crystal panel according to a third embodiment; (b) is a schematic cross-sectional view showing another example of a liquid crystal panel according to a third embodiment. Fig. 10 is a schematic cross-sectional view showing a liquid crystal panel according to a fourth embodiment. FIG. 11 is an explanatory diagram showing the height difference of the optical laminate.

Claims (6)

A liquid crystal panel, comprising a liquid crystal cell, a first polarizer provided on the first surface side of the liquid crystal cell and having a substantially rectangular shape, and a second polarizer provided on the second surface side of the liquid crystal cell and having a substantially rectangular shape. The first polarizer has an absorption axis extending in a long direction thereof, and the second polarizer has an absorption axis extending in a short direction thereof; the first polarizer and the second polarizer are disposed so as to absorb each other's axis The extending direction of the electrodes intersects vertically; the thickness of the second polarizer is greater than the thickness of the first polarizer. For example, the liquid crystal panel of claim 1, wherein the ratio (T1 / T2) of the thickness (T1) of the first polarizer to the thickness (T2) of the second polarizer is 1/10 to 1/2. For example, the liquid crystal panel of claim 1, wherein the difference (T2-T1) between the thickness (T2) of the second polarizer and the thickness (T1) of the first polarizer is 2 μm or more. In the liquid crystal panel according to any one of claims 1 to 3, a protective film is laminated on at least any one of the first polarizer and the second polarizer. A liquid crystal display device having a liquid crystal panel according to any one of claims 1 to 3. A set of polarizers is characterized in that it has a slightly rectangular first polarizer and a slightly rectangular second polarizer; the first polarizer has an absorption axis extending in its length direction, and the second polarizer has The absorption axis extended in the short direction; the first polarizer and the second polarizer are arranged so that the extension directions of the absorption axes intersect perpendicularly; the thickness of the second polarizer is greater than the thickness of the first polarizer.