JP2005049779A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate excellent in durability and causing no trouble on light leakage even when a polarizing film is thin and giving a liquid crystal display device having high display quality, and the liquid crystal display device equipped with the polarizing plate. <P>SOLUTION: In the polarizing plate, the transmittance of 410nm where crossed Nichol is ≥0 and <0.14%, and boric acid content per volume of the polarizing film is ≥200kg/m<SP>3</SP>and ≤480kg/m<SP>3</SP>, and the film thickness of the polarizing film is ≥5μm and ≤25μm. Then, the polarizing plate has an optical compensating sheet equipped with an optical anisotropic layer formed of a liquid crystal compound instead of a protection film as request. Then, the liquid crystal display device equipped with the polarizing plate is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polarizing plate excellent in durability, particularly durability under high humidity conditions, and a liquid crystal display device using the polarizing plate. The present invention particularly relates to a polarizing plate and a liquid crystal display device including an optical compensation film with little light leakage.

The demand for polarizing plates is rapidly increasing with the spread of liquid crystal display devices (hereinafter referred to as LCDs). In the polarizing plate, a protective film is generally bonded to both surfaces or one surface of a polarizing layer having polarizing ability via an adhesive layer.
As a material for the polarizing layer, polyvinyl alcohol (hereinafter referred to as PVA) is mainly used. After the PVA film is uniaxially stretched, it is dyed with iodine or a dichroic dye, or is stretched after being dyed. A polarizing film for a polarizing layer is formed by crosslinking with a boron compound. Since the absorption axis of the polarizing film is usually uniaxially stretched in the longitudinal direction, it is substantially parallel to the longitudinal direction.
As another stretching method, in Patent Document 1 (Japanese Patent Laid-Open No. 2000-9912), the plastic film is uniaxially stretched horizontally or vertically, and the left and right of the stretching direction are different from the stretching direction at different speeds. In a method in which the orientation axis is inclined with respect to the uniaxial stretching direction by stretching in the longitudinal or lateral direction, Patent Document 2 (Japanese Patent Laid-Open No. 3-182701), the running direction and θ It has a plurality of pairs of left and right film holding points that form an angle of, and each film has a stretching axis at an arbitrary angle θ with respect to the traveling direction of the film by a mechanism that can stretch each paired point in the direction of θ as the film travels. In the method for producing a film, Patent Document 3 (Japanese Patent Laid-Open No. 2-113920), the both ends of the film are moved within a predetermined travel section. Manufacturing method for stretching in a direction oblique to the length direction of the film by gripping and running between two rows of chucks running on tenter rails that are arranged so as to be different from each other, Patent Document 4 And the oblique stretching method described in JP-A-2002-86554).
These methods can incline the orientation axis of the polymer at a desired angle with respect to the film conveying method. However, the methods of Patent Documents 1 to 3 cause creases, wrinkles, and stretching unevenness in the film. Has a disadvantage that the stretching process needs to be very long and the equipment cost becomes high, and the method of Patent Document 4 has solved these problems. This method is an excellent method that can increase the yield by tilting the absorption axis to 45 degrees, particularly in a large-size polarizing plate.

A polarizing plate manufactured by a conventional uniaxial stretching method has a polarizing film thickness of about 26 μm. Especially, the polarizing film shrinks with time in a liquid crystal monitor of 17 inches or more. There has been a high demand for reducing the thickness of the polarizing film from the viewpoint of failure (frame failure) that occurs and frame weight reduction in portable applications. Furthermore, in the TN mode TFT liquid crystal display devices which are currently mainstream, Patent Document 5 (Japanese Patent Laid-Open No. 7-191217) and Patent Document 6 (European Patent 0911656A2) describe a discotic ( It is described that the front contrast can be increased without increasing the thickness of the liquid crystal display device by directly using an optical compensation film provided with an optically anisotropic layer made of a (discotic) compound as a protective film for a polarizing plate. is there. The retardation film (optical compensation sheet) of the present invention has a phase difference due to distortion such as heat, and when a polarizing plate using the optical compensation film as a protective film is mounted on a large panel of 17 inches or more, It has been found that light leakage due to thermal strain is not completely eliminated. The strain described above is related to the photoelastic coefficient of the optical compensation sheet, the thickness, the virtual strain due to the environment, and the elastic modulus, the thickness of the polarizing film, the dimensional change, and the elastic modulus. It has been found that can be greatly improved.
The method of reducing the thickness of the polarizing film can be achieved by increasing the draw ratio or decreasing the film thickness of the PVA film. However, it has become clear that as the polarizing plate polarizing film is made thinner, the degree of polarization decreases under durability, particularly under high humidity conditions. This problem becomes prominent when the thickness of the polarizing film is 25 μm or less, and particularly prominent when the thickness of the polarizing film is 20 μm or less. For this reason, the commercially available polarizing plate is usually from 26 μm to 30 μm, and the thinnest is 22.5 μm.
Furthermore, the decrease in the degree of polarization under high-humidity conditions is not improved even by the other stretching methods described above (Patent Documents 1 to 4), and it has become clear that this is a common problem regardless of the stretching method. It was.

JP 2000-9912 A Japanese Patent Laid-Open No. 3-182701 Japanese Patent Laid-Open No. 2-113920 JP 2002-86554 A Japanese Patent Laid-Open No. 7-191217 European Patent 0911656A2

An object of the present invention is to provide a polarizing plate that is excellent in durability, especially in the degree of polarization under high humidity, even when the polarizing film is thin.
Another object of the present invention is to provide a polarizing plate having a polymer film obtained by an oblique stretching method and having an obliquely stretched polymer film capable of improving the yield in the polarizing plate punching process as a polarizing film. There is also.
Another object of the present invention is to provide an optical compensation sheet on one side of a polarizing film and use it in a liquid crystal display device, thereby providing a liquid crystal display device with high display quality without causing problems such as light leakage. To provide a board.
A polarizing plate that achieves these objects has not been provided so far, and is provided for the first time in the present invention.
A further object of the present invention is to provide a method for producing the polarizing plate and a liquid crystal display device provided with the polarizing plate.

The present inventors have intensively studied to prevent a decrease in the degree of polarization of the polarizing plate under high humidity conditions. as a result,
1) 410 nm transmittance during crossed Nicol,
2) boric acid content per volume of polarizing film, and 3) film thickness of polarizing film of polarizing plate,
It was found for the first time that the degree of polarization degree reduction of a polarizing plate under high humidity conditions is determined by these three factors. Also, from this result, even when the polarizing film of the polarizing plate is thin, the degree of polarization under high humidity conditions is adjusted by adjusting the transmittance at 410 nm in crossed Nicols and the boric acid content per volume of the polarizing film. It has been found that the reduction can be improved. In the present invention, the boric acid content per volume is a value obtained by dividing the boric acid amount per unit area contained in the polarizing film by the film thickness of the polarizing film, and the unit is kg / m ³ .
According to the present invention, a polarizing plate and a liquid crystal display device having the following constitution are provided, and the object of the present invention is achieved.
1. The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.14%, the boric acid content per volume of the polarizing film is 200 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. A polarizing plate having a thickness of 25 μm or less.
2. The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.19%, the boric acid content per volume of the polarizing film is 230 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. A polarizing plate having a thickness of 25 μm or less.
3. 2. The polarizing plate according to 1 above, wherein the transmittance at 410 nm in crossed Nicol is 0 or more and less than 0.10%, and the thickness of the polarizing film is 5 μm or more and 22 μm or less.
4). The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.16%, the boric acid content per volume of the polarizing film is 260 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. 3. The polarizing plate according to 2 above, which is 22 μm or less.
5. The transmittance at 410 nm at the time of crossed Nicols is 0 or more and less than 0.10%, the boric acid content per volume of the polarizing film is 230 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 2. The polarizing plate according to 1 above, which is 5 μm or more and 20 μm or less.
6). The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.14%, the boric acid content per volume of the polarizing film is 290 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 3. The polarizing plate according to 2 above, which is 5 μm or more and 20 μm or less.
7. The polarizing plate as described in any one of 1 to 6 above, wherein the single plate transmittance is 42% or more and the degree of polarization is 99.9% or more.
8). A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein at least one of the transparent protective films is made of a cellulose acetate film and has a thickness in the range of 10 to 70 μm. The polarizing plate according to any one of 1 to 7 above.
9. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof,
One of the transparent protective films is a cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of the cellulose acetate. An optical compensation sheet comprising an optically anisotropic layer formed of a liquid crystalline compound on a cellulose acetate film containing 0.01 to 20 parts by mass, and is defined by the following mathematical formula (1) of the cellulose acetate film. The Re retardation value is in the range of 0 to 20 nm, the Rth retardation value defined by the following formula (2) is in the range of 70 to 400 nm, and the thickness is in the range of 10 to 70 μm. 9. The polarizing plate according to 8 above.
Formula (1): Re = (nx−ny) × d
Formula (2): Rth = {(nx + ny) / 2−nz} × d
[In the above formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the refractive index in the thickness direction of the film. And d is the thickness of the film].
10. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof,
One of the transparent protective films is a cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of the cellulose acetate. An optical compensation sheet comprising an optically anisotropic layer formed of a liquid crystalline compound on a cellulose acetate film containing 0.01 to 20 parts by mass, and is defined by the following mathematical formula (1) of the cellulose acetate film. The Re retardation value is in the range of 0 to 20 nm, the Rth retardation value defined by the following formula (2) is in the range of 0 to 40 nm, and the thickness is in the range of 10 to 70 μm. 9. The polarizing plate according to 8 above.
Formula (1): Re = (nx−ny) × d
Formula (2): Rth = {(nx + ny) / 2−nz} × d
[In the above formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the refractive index in the thickness direction of the film. And d is the thickness of the film].
11. 11. The polarizing plate as described in 9 or 10 above, wherein the Re retardation value is in the range of 0 to 5 nm.
12 12. A liquid crystal display device, wherein the polarizing plate according to any one of 1 to 11 is used for at least one of two polarizing plates disposed on both sides of a liquid crystal cell.

  According to the present invention, it is possible to provide an excellent polarizing plate that has little durability, particularly a decrease in degree of polarization under high humidity, even when the polarizing film is thin. Furthermore, it can be applied to a high-performance and inexpensive polarizing plate by having, as a polarizing film, a polymer film obtained by an oblique stretching method and capable of improving the yield in the polarizing plate punching process. Further, by disposing the optical compensation sheet on one side of the polarizing film and using it in the liquid crystal display device, a liquid crystal display device with high display quality can be provided without causing problems such as light leakage.

The degree of decrease in the degree of polarization of the polarizing plate of the present invention under high humidity conditions is determined by the combination of the above three factors. When the thickness of the polarizing film is determined, the transmittance at 410 nm and the volume of the polarizing film at the time of crossed Nicols are determined. The boric acid content per unit is also determined.
When the film thickness of the polarizing film of the polarizing plate is 5 μm or more and 25 μm or less: 1) 410 nm transmittance during crossed Nicols: 0 or more and less than 0.14% Boric acid content per volume of polarizing film: 200 kg / m ³ or more and 480 kg / M ³ or less 2) 410 nm transmittance during crossed Nicols: 0 or more and less than 0.19% Boric acid content per volume of polarizing film: 230 kg / m ³ or more and 480 kg / m ³ or less Range of 1) or 2) above If it is in.
When the film thickness of the polarizing film of the polarizing plate is 5 μm or more and 22 μm or less, 3) 410 nm transmittance during crossed Nicols: 0 or more and less than 0.10% Boric acid content per volume of polarizing film: 200 kg / m ³ or more and 480 kg / M ³ or less 4) 410 nm transmittance during crossed Nicols: 0 or more and less than 0.16% boric acid content per volume of polarizing film: 260 kg / m ³ or more and 480 kg / m ³ or less 3) or 4) above If it is in.
5) When the film thickness of the polarizing film of the polarizing plate is 5 μm or more and 20 μm or less 5) Transmittance at 410 nm in crossed Nicols: 0 or more and less than 0.10% Boric acid content per volume of polarizing film: 230 kg / m ³ or more and 480 kg / M ³ or less 6) Transmittance at 410 nm in crossed Nicols: 0 or more and less than 0.14% Boric acid content per volume of polarizing film: 290 kg / m ³ or more and 480 kg / m ³ or less 5) or 6) above If it is in.
In either case, as the thickness of the polarizing film of the polarizing plate becomes thinner, the transmittance at 410 nm at the time of crossed Nicols is low, and the boric acid content per volume of the polarizing film needs to be increased.
The lower limit of the transmittance at 410 nm at the time of crossed Nicols is preferably as low as possible, but if it is too low, the phenomenon that the single plate transmittance is lowered occurs, so it is practically less than 0.01%. Further, the upper limit of the boric acid content per volume is preferably as large as possible, but if it is too large, the transmittance of the long wave part (from 600 nm to 700 nm) at the time of crossed nicols is increased, and the hue is unfavorable due to redness. Actually, it is 480 kg / m ³ or less.

<Method of reducing the transmittance at 410 nm during crossed Nicols>
The method of lowering the transmittance of 410 nm at the time of crossed Nicols can be performed in the dyeing process and the dura hardening process for producing a polarizing film described later.
In particular,
1) Increase the amount of iodine dyed in the dyeing step 2) Adjust the amount of potassium iodide in the dura mater in the dura mating step 3) Add iodine to the dura mater in the dura mating step 4) Dye liquor step There are means such as adding boric acid to the dyeing solution.
Among these, the means 1) is not preferable because the single plate transmittance of the polarizing plate is lowered and the quality is lowered. The means 2) to 4) are preferred, and the means 2) and 3) are particularly preferred. Not only these means but also other means for reducing the 410 nm transmittance during crossed Nicol can be used. These means can be used in combination.

<Method of increasing boric acid content per volume>
The method for increasing the boric acid content per volume can be performed in the hardening step in the polarizing film production described later.
In particular,
1) Increasing the temperature of the hardening solution 2) Increasing the hardening process time 3) Increasing the boric acid concentration of the hardening solution.
Not only these means but also other means for increasing the boric acid content per volume can be used. These means can be used in combination.

A method for reducing the transmittance at 410 nm during crossed Nicol and a method for increasing the boric acid content per volume can be achieved by the above-described means.
In the above method, the simplest method is a method of adjusting only the hardening step, and a preferable operation method will be described below.
The hardening step is a step of adding boric acid as a cross-linking agent to a PVA film containing higher-order iodine ions for cross-linking. In the hardening step, it is preferable to immerse in a boric acid solution or apply the solution to include a crosslinking agent. Further, as described in JP-A-11-52130, the hardening process can be performed in several steps. As cross-linking agents other than boric acid, those described in US Pat. No. 2,328,979 can be used together. As described in Japanese Patent No. 3357109, a cross-linking agent is used as a cross-linking agent in order to improve dimensional stability. Divalent aldehydes can also be used. When boric acid is used as the cross-linking agent used in the hardening step, metal ions may be added to the boric acid-potassium iodide aqueous solution. Zinc chloride is preferable as the metal ion, but as described in JP-A-2000-35512, zinc halide such as zinc iodide, zinc sulfate such as zinc acetate, and zinc acetate are used instead of zinc chloride. It can also be used.
In the present invention, it is preferable to prepare an aqueous boric acid-potassium iodide solution and immerse the PVA film to perform hardening. The boric acid is preferably 1 to 100 g / L, the potassium iodide is preferably 1 to 120 g / L, the hardening time is preferably 10 to 1200 seconds, and the liquid temperature is preferably 10 to 70 ° C. More preferably, boric acid is 10 to 80 g / L, potassium iodide is 5 to 100 g / L, iodine has a hardening time of 30 to 600 seconds, and a liquid temperature of 20 to 60 ° C. When adding iodine, 0.001 to 1 g / L is preferable, and 0.01 to 0.5 g / L is more preferable. In this case, the mass ratio of iodine and potassium iodide (iodine: potassium iodide) is preferably 1:10 to 1: 10000, more preferably 1: 100 to 1: 5000.
Moreover, when adding zinc chloride as a metal ion, it is 0.01-10 g / L, More preferably, it is 0.02-8 g / L.

<Method of reducing the thickness of the polarizing film>
The method of reducing the thickness of the polarizing film can be achieved by a method of increasing the draw ratio and reducing the thickness of the PVA film in the conventional stretching method. The film thickness of the commonly used PVA film is 75 μm (for example, Kuraray VF-P, VF-PS, etc.). In this case, when the film is stretched by about 8 times or more in the longitudinal uniaxial stretching method, The film thickness is 20 μm or less. If the horizontal uniaxial stretching method is stretched 4 times or more by a tenter method or the like, the thickness of the polarizing film becomes 20 μm or less. Moreover, the film thickness of a polarizing film will be 20 micrometers or less by making the film thickness of a PVA film into 50 micrometers or less and extending | stretching about 6 times or more by uniaxial stretching.
In the present invention, in addition to these uniaxial stretching methods, a stretching method in which the polarizing film polymer film is produced by uniaxial stretching in the transport direction or after uniaxial stretching and then stretching in the transverse direction can also be used. This method is a method generally called biaxial stretching. As a general method, a simultaneous biaxial stretching method using a tenter method, a simultaneous biaxial stretching method using a tubular method, and the like are known. In this method, when a 75 μm thick PVA film is stretched about 4 times or more in the vertical direction and about 1.5 times or more in the horizontal direction, the thickness of the polarizing film becomes 20 μm or less.
A preferred stretching method in the present invention is an oblique stretching method described in Patent Document 4 (Japanese Patent Laid-Open No. 2002-86554). In this stretching method, the thickness of the polarizing film is 20 μm or less by stretching a PVA film having a PVA film thickness of less than 100 μm 5 times or more.
In the present invention, from the viewpoint of failure that causes light leakage (frame failure) and weight reduction of the polarizing plate member, the polarizing film is preferably thin. However, if it is too thin, the film may be cut or dyed during stretching. Problems such as adversely affecting the handling when immersed in a liquid / hardening fluid and cracking during drying after stretching occur. Therefore, in the present invention, the thickness of the polarizing film is preferably 5 μm or more and 25 μm or less, more preferably 8 μm or more and 22 μm or less, and most preferably 10 μm or more and 20 μm or less.

Hereinafter, the polarizing plate in the present invention will be described in detail.
1. First, the polarizing film and the protective film constituting the polarizing plate of the present invention will be described.
(1) Polarizing film The polarizing film of the present invention is preferably composed of polyvinyl alcohol (PVA) and a dichroic molecule. Further, as described in JP-A-11-248937, a polyvinylene polarizing film in which a polyene structure is formed by dehydrating and dechlorinating PVA or polyvinyl chloride and oriented can be used. .

  PVA is a polymer material obtained by saponifying polyvinyl acetate, but may contain components copolymerizable with vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, and vinyl ethers. In addition, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like can also be used.

The saponification degree of PVA is not particularly limited, but is preferably 80 to 100 mol%, particularly preferably 90 to 100 mol% from the viewpoint of solubility and the like. The degree of polymerization of PVA is not particularly limited, but is preferably 1000 to 10,000, and particularly preferably 1500 to 5000.
The syndiotacticity of PVA is preferably 55% or more for improving durability as described in Japanese Patent No. 2978219, but it is 45 to 52.5% described in Japanese Patent No. 3317494. Can also be preferably used.

  PVA is preferably formed into a film and then a dichroic molecule is introduced to form a polarizing film. As a method for producing a PVA film, a method of forming a film by casting a stock solution in which a PVA resin is dissolved in water or an organic solvent is generally preferably used. The density | concentration of the polyvinyl alcohol-type resin in a stock solution is 5-20 mass% normally, and a PVA film with a film thickness of 10-200 micrometers can be manufactured by forming this stock solution with a casting method. The PVA film can be produced with reference to Japanese Patent No. 3342516, Japanese Patent Application Laid-Open No. 09-328593, Japanese Patent Application Laid-Open No. 2001-302817, and Japanese Patent Application Laid-Open No. 2002-144401.

The crystallinity of the PVA film is not particularly limited. However, in order to reduce the average crystallinity (Xc) of 50 to 75% by weight and the in-plane hue variation described in Japanese Patent No. 3251073, Japanese Patent Application Laid-Open No. Hei 14 A PVA film having a crystallinity of 38% or less described in JP-A-236214 can be used.
The birefringence (Δn) of the PVA film is preferably small, and a PVA film having a birefringence of 1.0 × 10 ⁻³ or less described in Japanese Patent No. 3342516 can be preferably used. However, as described in JP-A-14-228835, the birefringence of the PVA film is set to 0.02 or more and 0.01 or less in order to obtain a high degree of polarization while avoiding cutting at the time of stretching the PVA film. Alternatively, as described in JP-A-14-060505, the value of (nx + ny) / 2−nz may be set to 0.0003 or more and 0.01 or less. The retardation (in-plane) of the PVA film is preferably from 0 nm to 100 nm, and more preferably from 0 nm to 50 nm. Moreover, 0 nm or more and 500 nm or less are preferable, and, as for Rth (film thickness direction) of a PVA film, 0 nm or more and 300 nm or less are more preferable.

In addition, the polarizing plate of the present invention includes a PVA film having a 1,2-glycol bond amount of 1.5 mol% or less described in Japanese Patent No. 3021494, and JP-A-2001-316492. The PVA film in which the number of optical foreign matters of 5 μm or more is 500 or less per 100 cm ² , and the hot-water cutting temperature spot in the TD direction of the film described in JP-A-2002-030163 is 1.5 ° C. or less Made from a solution in which 1 to 100 parts by weight of a polyvalent alcohol such as glycerin is added to PVA film or 15% by weight or more of a plasticizer described in Japanese Patent Application Laid-Open No. 06-289225. A filmed PVA film can be preferably used.

  Although the film thickness before extending | stretching of a PVA film is not specifically limited, 1 micrometer-1 mm are preferable and 20-200 micrometers is especially preferable from a viewpoint of stability of film holding | maintenance and the uniformity of extending | stretching. As described in JP-A-2002-236212, a thin PVA film may be used in which the stress generated when stretching 4 to 6 times in water is 10 N or less.

The dichroic molecules, I ₃ ^- and I ₅ ^- can be preferably used an iodine ion or a dichroic dye higher such. In the present invention, higher-order iodine ions are particularly preferably used. Higher-order iodine ions were dissolved in potassium iodide aqueous solution as described in “Application of Polarizing Plate” by Nagata Ryo, CMC Publishing, Industrial Materials, Vol. 28, No. 7, p39-p45. PVA can be immersed in a liquid and / or boric acid aqueous solution, and can be produced in a state of being adsorbed and oriented in PVA.
When a dichroic dye is used as the dichroic molecule, an azo dye is preferable, and a bisazo dye and a trisazo dye are particularly preferable. The dichroic dye is preferably a water-soluble dye. For this reason, a hydrophilic substituent such as a sulfonic acid group, an amino group or a hydroxyl group is introduced into the dichroic molecule, so that a free acid, an alkali metal salt, an ammonium salt or an amine is introduced. It is preferably used as a salt.

  Specific examples of such dichroic dyes include, for example, CIDirect Red 37, Congo Red (CI Direct Red 28), CIDirect Violet 12, CIDirect Blue 90, CIDirect Blue 22, CIDirect Blue 1, CI Benzidines such as Direct Blue 151 and CIDirect Green 1, diphenylureas such as CIDirect Yellow 44, CIDirect Red 23 and CIDirect Red 79, stilbenes such as CIDirect Yellow 12, and dinaphthylamines such as CIDirect Red 31 And CI acid red such as CIDirect Red 81, CIDirect Violet 9 and CIDirect Blue 78.

  Besides this, CIDirect Yellow 8, CIDirect Yellow 28, CIDirect Yellow 86, CIDirect Yellow 87, CIDirect Yellow 142, CIDirect Orange 26, CIDirect Orange 39, CIDirect Orange 72, CIDirect Orange 106, CIDirect Orange 107, CIDirect Red 2, CIDirect Red 39, CIDirect Red 83, CIDirect Red 89, CIDirect Red 240, CIDirect Red 242, CIDirect Red 247, CIDirect Violet 48, CIDirect Violet 51, CIDirect Violet 98, CIDirect Blue 15, CIDirect Blue 67, CIDirect Blue 71, CIDirect Blue 98, CIDirect Blue 168, CIDirect Blue 202, CIDirect Blue 236, CIDirect Blue 249, CIDirect Blue 270, CIDirect Green 59, CIDirect Green 85, CIDirect Brown 44, CIDirect Brown 106, CIDirect Brown 195, CIDirect Brown 210, CIDirect Brown 223, CIDirect Bro wn 224, CIDirect Black 1, CIDirect Black 17, CIDirect Black 19, CIDirect Black 54, and the like are further disclosed in Japanese Patent Laid-Open Nos. 62-70802, 1-161202, and 1-172906. Dichroic dyes described in JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP-A-1-265205, and JP-A-7-261024. Etc. can also be preferably used. In order to produce dichroic molecules having various hues, two or more of these dichroic dyes may be blended. When a dichroic dye is used, the adsorption thickness may be 4 μm or more as described in JP-A-2002-082222.

  If the content of the dichroic molecule in the film is too small, the degree of polarization is low, and if it is too much, the single plate transmittance is lowered. Usually, it is adjusted in the range of 0.01% by mass to 5% by mass with respect to the polyvinyl alcohol polymer constituting the matrix of the film.

  The preferred thickness of the polarizing film is preferably 5 μm to 40 μm, more preferably 10 μm to 30 μm. The ratio between the thickness of the polarizing film and the thickness of the protective film described later is set to 0.01 ≦ A (polarizing film thickness) / B (protective film thickness) ≦ 0 as described in JP-A No. 2002-174727. A range of 16 is preferable.

(2) Protective film The polarizing film is preferably used by being bonded to both surfaces or one surface using an adhesive or a pressure sensitive adhesive with a transparent polymer film as a protective film. The protective film is required to have physical properties such as transparency, low birefringence, and moderate rigidity.
The transmittance of the transparent polymer film used for the protective film of the present invention is preferably 80% or more, and more preferably 87% or more. The haze of the transparent polymer film is preferably 2.0% or less, and more preferably 1.0% or less. The refractive index of the transparent polymer film is preferably 1.4 to 1.7.

  The material for the transparent polymer film is not particularly limited, and examples thereof include norbornene resin, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, polyarylate, polysulfone, and cellulose acylate. Commercially available polymer films include ZEONEX and ZEONOR manufactured by Nippon Zeon Co., Ltd., ARTON manufactured by Nippon Synthetic Rubber Co., Ltd., and Fujitac manufactured by Fuji Photo Film Co., Ltd. And Zeonor (manufactured by Nippon Zeon Co., Ltd.) are particularly preferred. The transparent polymer films on both sides of the polarizer may be the same or different. These commercially available polymer films are disclosed in reference materials: JP-A 63-218726, JP-A-5-25220, JP-A 9-183832, JP-A 2000-4051, JP-A 5-97978, Japanese Patent Laid-Open No. 7-11055, Japanese Society of Invention Disclosure Techniques 2001-1745, and the like.

The protective film disposed on the liquid crystal cell side is preferably a polymer film that does not substantially change the polarization state of light incident from the front, that is, has a small in-plane retardation (Re). Specifically, the Re value represented by the following formula (1) is preferably 0 nm or more and 20 nm or less, and particularly preferably 0 nm or more and 5 nm or less. The Rth value represented by the following mathematical formula (2) is preferably 0 nm or more and 400 nm or less, and when the higher Rth is used, it is preferably 70 nm to 400 nm, and most preferably 80 nm to 300 nm. On the other hand, when the lower Rth is used, 0 nm to 40 nm is preferable, and 0 nm to 20 nm is most preferable.
Formula (1): Re value = (nx−ny) × d
Formula (2): Rth value = ((nx + ny) / 2−nz) × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the direction perpendicular to nx in the film plane, nz is the refractive index in the thickness direction of the transparent support, and d is the transparent support. Represents the thickness of
The crossing angle between the slow axis of the protective film and the absorption axis of the polarizing film may be any value, but is preferably parallel or an azimuth angle of 45 ± 20 °.

The thickness of the protective film is preferably 30 μm to 120 μm, more preferably 40 μm to 100 μm, and most preferably 40 μm to 80 μm.
When used as a support for an optical compensation film described later, the thickness of the transparent polymer film is preferably in the range of 10 to 70 μm, more preferably in the range of 20 to 60 μm, and most preferably in the range of 30 to 50 μm. .
The moisture permeability coefficient (25 μm, 25 ° C., 90% RH) of the transparent polymer film is preferably 0.0001 to 1000 g / m ² · day, and the temperature shrinkage is 2 × 10 ⁻⁵ / ° C. to 9 × 10 ⁻⁵ / ° C. is preferable, and the humidity shrinkage is preferably 7 × 10 ⁻⁵ /% RH or less. Further, as described in JP-A No. 2001-235625, 40 ° C., 90% R.D. A transparent polymer film having a moisture permeability of H of 0.04 g / cm ² · 24 h or less can also be preferably used for the protective film.

The tensile strength value by the tensile test of the transparent polymer film is preferably 50 to 1000 MPa, and the elongation at break is preferably 5% or more and 100% or less. As described in JP-A-08-122525, a cellulose film having a tensile strength in the MD direction of 15 kg / mm ² or more and a tensile strength in the TD direction of 12.5 kg / mm ² or more may be used. As described in JP-A-09-251110, a cellulose-based film having a tensile strength of 13 kgf / mm ² or more may be used. The photoelastic coefficient of the polymer film may be 25.0 × 10 ⁻¹³ cm ² / dyne or less described in JP-A-07-294732, but in the present invention, it is 9 × 10 ⁻¹³ cm ² / dyne. The following are particularly preferred:

  When a cellulose acylate film is used for the protective film, it is preferable to use a cellulose acylate film described in JIII Journal of Technical Disclosure No. 2001-1745. In addition, a cellulose acylate film having a phase difference of 8 nm or less in a viewing angle range within 30 degrees from the normal to the plane described in Japanese Patent No. 3327410, and foreign substances recognized in a crossed Nicol state are disclosed in A cellulose acylate film in the range described in JP-A-12-204173 can also be preferably used as the polarizing plate of the present invention. Among the cellulose acylate films, a cellulose acetate film is particularly preferable.

  As the raw material cotton for cellulose acylate used in the present invention, a known raw material can be used according to the Invention Association Open Technique No. 2001-1745. The cellulose acylate material can be synthesized by a known method such as wood chemistry 180-190 (Kyoritsu Shuppan, Mita et al., 1968). The viscosity average degree of polymerization of the cellulose acylate is preferably 200 to 700, more preferably 250 to 500, and most preferably 250 to 350.

  The acyl group of the cellulose acylate film is not particularly limited, but is preferably an acetyl group or a propionyl group, and particularly preferably an acetyl group. The degree of substitution of all acyl groups is preferably 2.7 to 3.0, more preferably 2.8 to 2.95. When cellulose acetate in which all acyl groups are acetyl groups is used, the degree of acetyl substitution is preferably 2.7 to 2.95, more preferably 2.8 to 2.95, and most preferably 2.84 to 2.89. . Further, those having an acetyl substitution degree of 2.50 or more and 2.86 or less described in JP-A No. 2001-356214, or 2.75 or more and 2.86 or less described in JP-A No. 13-226495. Those having an acetyl substitution degree of can also be preferably used. If the degree of acetyl substitution is too low, there is a problem that Re is likely to be larger than a desired value due to the conveyance tension during casting, and in-plane variation is likely to occur. Further, the substitution degree of the acyl group at the 6-position is preferably 0.9 or more. When the degree of substitution is 0.9 or less, variations in Re and Rth tend to occur. In addition, the value computed according to ASTM D817 is employ | adopted for the substitution degree of the acyl group in this patent.

  The cellulose acylate film used in the present invention is preferably produced by a solvent cast method. From the viewpoint of reducing variations in Re and Rth, the concentration of the cellulose acylate solution is preferably 16 to 30% by weight, and more preferably 18 to 26% by weight. The organic solvent used is not particularly limited, but a mixture of a chlorinated solvent, alcohols, ketones and esters is preferably used. As alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, as esters, methyl acetate is used, and as ketones, acetone, cyclopentanone, and cyclohexanone are particularly preferably used. From the viewpoint of protecting the global environment and improving the working environment, an organic solvent substantially not containing a chlorinated solvent may be used. “Substantially free” means that the proportion of the chlorinated solvent in the organic solvent is less than 10% by mass, preferably less than 5% by mass.

  In order to prepare a cellulose acylate solution, the cellulose acylate is first swelled by adding the cellulose acylate while stirring the solvent in the tank at room temperature. The swelling time is required to be at least 10 minutes, and insoluble materials remain after 10 minutes. The solvent temperature is preferably 0 to 40 ° C. If the temperature is 0 ° C. or lower, the swelling rate tends to decrease and insoluble matter tends to remain. If the temperature is 40 ° C. or higher, the swelling rapidly occurs and the central portion does not swell sufficiently. As a method for dissolving cellulose acylate, either a cooling dissolution method, a high temperature dissolution method, or both may be used. As a specific method relating to the cooling dissolution method and the high temperature dissolution method, a known method described in JIII Journal of Technical Disclosure No. 2001-1745 can be used. In some cases, the cellulose acylate solution obtained above can be preferably prepared by dissolving it at a low concentration and then concentrating it to an optimum concentration using a concentration means.

  Prior to casting, it is preferable to filter off foreign matters such as undissolved matter, dust, and impurities using a suitable filter medium such as a wire mesh, paper, or flannel. Although a method is not specifically limited, The well-known method described in the invention association open technique 2001-1745 grade etc. can be used.

  In the cellulose acylate solution of the present invention, various additives depending on the application can be added in each preparation step. These additives include plasticizers, UV inhibitors and degradation inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines), and release agents. , Fine particles and the like. Further, a retardation adjusting agent may be used in order to control the retardation of the film and its wavelength dependency within a possible range. The retardation adjusting agent is not particularly limited, but preferably has a maximum absorption in the wavelength region of 250 to 400 nm and substantially no absorption in the visible region. The addition amount of each additive is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, with respect to 100 parts by mass of the polymer. Most preferably, it is used in the range of 5 to 2 parts by mass.

  As a method and equipment for forming the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolution tank (pot) is temporarily stored in a stock tank, and the foam contained in the dope is defoamed for final preparation. The dope is fed from a dope discharge port to a pressurizing die through a pressurizing quantitative gear pump capable of quantitatively feeding the dope with high accuracy, and the dope is run endlessly from the die (slit) of the pressurizing die. The dry-dried dope film (also referred to as a web) is peeled from the metal support at the peeling point where the metal support has been uniformly cast on the substrate and has substantially gone around. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose.

In the present invention, in order to obtain the desired Re, the film can be stretched by expanding the width of the tenter outlet from the tenter inlet. The draw ratio varies depending on the desired Re, but is preferably 1.0 to 1.3 times, more preferably 1.0 to 1.25 times.
The amount of residual solvent in the stretched film is preferably 2% by mass to 35% by mass, and more preferably 2% by mass to 30% by mass. If the amount of residual solvent is less than 2% by mass, creases may occur or the film may break in some cases. If it is 35% by mass or more, the effect of stretching is small and Re may not be adjusted. Further, in order to adjust Re, the tension during conveyance may be adjusted within a range that does not cause a problem in handling.

In the present invention, in order to reduce the variation in film thickness and the variation in retardation, it is preferable to cast the cellulose acylate solution on a smooth band or drum as a metal support. A plurality of cellulose acylate solutions may be co-cast. The co-casting method is not particularly limited, and a method known in JP-A-11-198285 can be applied. Moreover, the method of forming into a film by casting a cellulose acylate solution from two casting openings may be used. Alternatively, a cellulose acylate film casting method may be used in which a flow of a high-viscosity cellulose acylate solution is wrapped with a low-viscosity cellulose acylate solution, and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. In the case of co-casting, the thickness of each layer is not particularly limited, but the outer layer is preferably thinner than the inner layer. In this case, the thickness of the outer layer is preferably 1 to 30 μm, particularly preferably 1 to 20 μm. Here, the outer layer refers to a surface that is not a band surface (drum surface) in the case of two layers, and layers on both surface sides of the completed film in the case of three or more layers. The inner layer is a band surface (drum surface) in the case of two layers. In the case of three or more layers, a layer located inside the outer layer is shown.
In addition, the cellulose acylate solution may be produced by simultaneously casting a solution for preparing other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorption layer, a polarizing layer). Good.

  Drying of the dope on the metal support used for producing the cellulose acylate film is preferably performed at 30 to 250 ° C, more preferably 40 to 180 ° C, and most preferably 40 to 140 ° C.

  The thickness of the finished cellulose acylate film (after drying) is preferably in the range of 20 to 100 μm, more preferably in the range of 20 to 80 μm, and most preferably in the range of 30 to 80 μm. The thickness of the film may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like. When a triacetyl cellulose film having a thickness of 50 μm or less is used, the elongation at break (under the condition of 23 ° C./60% RH) described in JP-A No. 14-022961 is 0. It is preferable to use a triacetyl cellulose film of .75% or less.

The maximum peak strength in the vicinity of 1488 cm ⁻¹ by the content of Ca, Fe, and Mg in the cellulose acylate film within the range described in JP 2000-313766 or ATR analysis on both sides of the film It is also preferable to use a triacetyl cellulose film whose ratio of the maximum peak strength in the vicinity of 1365 cm ⁻¹ is in the range described in JP-A No. 2002-258049.

  The polarizing plate of this invention may have an adhesive layer, a separate film, and a protective film as a component other than the above-mentioned polarizing film and protective film.

2. Next, the manufacturing process of the polarizing plate of the present invention will be described.
The production process of the polarizing plate in the present invention is preferably composed of a swelling process, a dyeing process, a hardening process, a stretching process, a drying process, a protective film bonding process, and a post-bonding drying process. The order of the dyeing process, the hardening process, and the stretching process may be arbitrarily changed, or some processes may be combined and performed simultaneously. Moreover, as described in Japanese Patent No. 3331615, it is also preferable to wash with water after the hardening step.

  In the present invention, it is particularly preferable to sequentially perform the swelling process, the dyeing process, the hardening process, the stretching process, the drying process, the protective film bonding process, and the drying process after bonding in the order described. An on-line surface inspection step may be provided during or after the above-described steps.

<Swelling process>
The swelling step is a step of swelling the polymer film used for forming the polarizing film with water. The swelling step is preferably carried out only with water, but as described in JP-A-10-153709, in order to stabilize optical performance and avoid wrinkling of the polarizing plate substrate in the production line, The degree of swelling of the polarizing plate substrate can also be managed by swelling the polarizing plate substrate with an aqueous boric acid solution.
Moreover, although the temperature and time of a swelling process can be defined arbitrarily, 10 to 60 degreeC and 5 to 2000 second are preferable.

<Dyeing process>
The dyeing step is a step of dyeing the polarizing film forming polymer film with a dichroic molecule such as iodine. As the dyeing step, the method described in JP-A-2002-86554 can be used. Moreover, as a dyeing method, not only immersion but arbitrary means, such as application | coating or spraying of an iodine or dye solution, are possible. Further, as described in JP-A-2001-290025, a method of dyeing while stirring the concentration of iodine, dye bath temperature, draw ratio in the bath, and bath solution in the bath may be used.
In the present invention, it is preferable to use higher-order iodine ions as the dichroic molecule, and in order to obtain a high-contrast polarizing plate, it is preferable to use a solution obtained by dissolving iodine in an aqueous potassium iodide solution in the dyeing step. In this case, iodine in the iodine-potassium iodide aqueous solution is preferably 0.05 to 20 g / L, potassium iodide is 3 to 200 g / L, and the mass ratio of iodine and potassium iodide is preferably 1 to 2000. The dyeing time is preferably 10 to 1200 seconds, and the liquid temperature is preferably 10 to 60 ° C. More preferably, iodine is 0.5-2 g / L, potassium iodide is 30-120 g / L, mass ratio of iodine and potassium iodide is 30-120, dyeing time is 30-600 seconds, and liquid temperature is 20-50 degreeC is good.
Further, as described in Japanese Patent No. 3145747, boron compounds such as boric acid and borax may be added to the dyeing solution.

<Hardening process>
The hardening process is performed in accordance with the method described above.
<Extension process>
For the stretching step, a longitudinal uniaxial stretching method as described in US Pat. No. 2,454,515 or a tenter method as described in JP-A-2002-86554 can be preferably used. A preferable draw ratio is 2 times or more and 12 times or less, and more preferably 3 times or more and 10 times or less.
Further, as described in JP-A-2002-040256, the relationship between the draw ratio, the thickness of the original film, and the thickness of the polarizing film (polarizing film thickness after bonding of protective film / raw film thickness) × ( (Total draw ratio)> 0.17, or the relationship between the width of the polarizing film when leaving the final bath and the width of the polarizing film when bonding the protective film is 0 as described in JP-A-2002-040247. It is also preferable to satisfy the following condition: 80 ≦ (polarizing film width at the time of bonding the protective film / width of the polarizing film when leaving the final bath) ≦ 0.95.

<Drying process>
Although the well-known method of Unexamined-Japanese-Patent No. 2002-86554 can be used for a drying process, a preferable temperature range is 30 to 100 degreeC, and preferable drying time is 30 second-60 minutes. Further, as described in Japanese Patent No. 3148513, a heat treatment is performed so that the fading temperature in water is 50 ° C. or more, and it is described in Japanese Patent Application Laid-Open Nos. 07-325215 and 07-325218. As described above, aging in a temperature and humidity controlled atmosphere can also be preferably performed.

<Protective film bonding process>
The protective film laminating step is a step of laminating both surfaces of the polarizing film from the drying step with two protective films. A method of bonding with a pair of rolls is preferably used so that the adhesive liquid is supplied immediately before bonding and the polarizing film and the protective film are overlapped. Further, as described in JP-A-2001-296426 and JP-A-2002-86554, in order to suppress the groove-like unevenness of the record due to stretching of the polarizing film, It is preferable to adjust the moisture content. In the present invention, a moisture content of 0.1% to 30% is preferably used.

The adhesive between the polarizing film and the protective film is not particularly limited, and examples thereof include PVA resins (including modified PVA containing acetoacetyl groups, sulfonic acid groups, carboxyl groups, oxyalkylene groups, etc.), boron compound aqueous solutions, and the like. Among them, PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 5 μm after drying, and particularly preferably 0.05 to 3 μm.
In order to improve the adhesive force between the polarizing film and the protective film, it is preferable that the protective film is surface-treated to be hydrophilic and then bonded. The surface treatment method is not particularly limited, and a known method such as a saponification method using an alkaline solution or a corona treatment method can be used. Further, an easy-adhesion layer such as a gelatin undercoat layer may be provided after the surface treatment. As described in JP-A-2002-267839, the contact angle of the protective film surface with water is preferably 50 ° or less.

  The drying conditions after bonding are in accordance with the method described in JP-A-2002-86554, but the preferred temperature range is 30 ° C. to 100 ° C., and the preferred drying time is 30 seconds to 60 minutes. It is also preferable to perform aging in an atmosphere with temperature and humidity control as described in JP-A-07-325220.

The element content in the polarizing film is as follows: iodine 0.1-3.0 g / m ² , boron 0.1-5.0 g / m ² , potassium 0.1-2.0 g / m ² , zinc 0-2. It is preferably 0 g / m ² . Further, the potassium content may be 0.2% by mass or less as described in JP-A No. 2001-166143, and the zinc content in the polarizing film is described in JP-A No. 2000-035512. It is good also as 0.04 mass%-0.5 mass% currently being carried out.

  As described in Japanese Patent No. 3323255, in order to increase the dimensional stability of the polarizing plate, an organic titanium compound and / or an organic zirconium compound is used in any of the dyeing process, the stretching process and the hardening process. In addition, the polarizing film may contain at least one compound selected from organic titanium compounds and organic zirconium compounds. A dichroic dye may be added to adjust the hue of the polarizing plate.

3. Characteristics of Polarizing Plate (1) Transmittance and Degree of Polarization The preferred single plate transmittance of the polarizing plate of the present invention is 42.0% or more and 49.5% or less, more preferably 42.5% or more and 49.0%. % Or less. A preferable range of the degree of polarization defined by the following formula (4) is 99.900% or more and 99.999% or less, and more preferably 99.940% or more and 99.995% or less. A preferable range of the parallel transmittance is 36% or more and 42% or less, and a preferable range of the orthogonal transmittance is 0.001% or more and 0.05% or less. The preferable range of the dichroic ratio defined by the following formula (5) is 48 or more and 1215 or less, and more preferably 53 or more and 525 or less.
The above-described transmittance is defined by the following mathematical formula (3) based on JIS Z 8701.

Formula (3)

Here, K, S (λ), y (λ), and τ (λ) are as follows.
K:

S (λ): spectral distribution of standard light used for color display y (λ): color matching function in XYZ system τ (λ): spectral transmittance

Formula (4)

Formula (5)

The iodine concentration and the single plate transmittance may be in the ranges described in JP-A-2002-258051.
The parallel transmittance may have a small wavelength dependency as described in Japanese Patent Laid-Open Nos. 2001-083328 and 2002-022950. The optical characteristics when the polarizing plates are arranged in crossed Nicols may be in the range described in Japanese Patent Laid-Open No. 2001-091736, and the relationship between parallel transmittance and orthogonal transmittance is disclosed in Japanese Patent Laid-Open No. 14-174728. It may be within the range described in the publication.

As described in Japanese Patent Application Laid-Open No. 14-221618, the standard deviation of the parallel transmittance every 10 nm when the light wavelength is between 420 and 700 nm is 3 or less, and the light wavelength is 420 to 700 nm. The minimum value of (parallel transmittance / orthogonal transmittance) every 10 nm may be 300 or more.
The parallel transmittance and orthogonal transmittance at a wavelength of 440 nm, the parallel transmittance and orthogonal transmittance at a wavelength of 550 nm, and the parallel transmittance and orthogonal transmittance at a wavelength of 610 nm of the polarizing plate are disclosed in JP-A Nos. 2002-258042 and 2002-258043. The range described in each of the above publications can also be preferably performed.

(2) Hue The hue of the polarizing plate of the present invention is preferably evaluated using the lightness index L ^* and the chromaticness index a ^* and b ^* in the L ^* a ^* b ^* color system recommended as the CIE uniform perceptual space. Is done.
L ^* , a ^* , and b ^* are defined by the following formula (6) using the above-described X, Y, and Z.

Formula (6)

Here, X ₀ , Y ₀ , Z ₀ represent tristimulus values of the illumination light source, and in the case of the standard light C, X ₀ = 98.072, Y ₀ = 100, Z ₀ = 118.225, and the standard In the case of the light D ₆₅ , X ₀ = 95.045, Y ₀ = 100, Z ₀ = 108.892.
The preferable range of a ^* for a single polarizing plate is −2.5 or more and 0.2 or less, and more preferably −2.0 or more and 0 or less. A preferable range of b ^* of the single polarizing plate is 1.5 or more and 5 or less, and more preferably 2 or more and 4.5 or less. The preferable range of a ^* of the parallel transmitted light of the two polarizing plates is −4.0 to 0, and more preferably −3.5 to −0.5. The preferred range of b ^* of the parallel transmitted light of the two polarizing plates is 2.0 or more and 8 or less, more preferably 2.5 or more and 7 or less. The preferable range of a ^* of the orthogonally transmitted light of the two polarizing plates is −0.5 or more and 1.0 or less, and more preferably 0 or more and 2 or less. The preferable range of b ^* of the orthogonally transmitted light of the two polarizing plates is −2.0 or more and 2 or less, and more preferably −1.5 or more and 0.5 or less.

The hue may be evaluated by the chromaticity coordinates (x, y) calculated from the aforementioned X, Y, and Z. For example, the chromaticity (x _p , y _p ) of the parallel transmitted light of the two polarizing plates. And the chromaticity (x _c , y _c ) of the orthogonal transmitted light are within the ranges described in JP 2002-214436 A, JP 2001-166136 A, JP 2002-169024 A, It is also preferable to make the absorbance relationship within the range described in JP-A-2001-311827.

(3) Viewing angle characteristics When a polarizing plate is arranged in crossed Nicol and light with a wavelength of 550 nm is incident, when vertical light is incident, from a azimuth of 45 degrees with respect to the polarization axis, 40 degrees with respect to the normal line It is also preferable that the transmittance ratio and the xy chromaticity difference when the light is incident at an angle of within the ranges described in Japanese Patent Laid-Open Nos. 2001-166135 and 2001-166137. In addition, as described in JP-A-10-068817, the light transmittance (T ₀ ) in the vertical direction of the polarizing plate laminated body arranged in crossed Nicols and the light in the direction inclined by 60 ° from the normal line of the laminated body The ratio (T ₆₀ / T ₀ ) with the transmittance (T ₆₀ ) is set to 10000 or less, or as described in JP-A-2002-139625, the polarizing plate has an arbitrary range from the normal to an elevation angle of 80 degrees. When natural light is incident at an angle, the transmittance difference of transmitted light within a wavelength range of 20 nm within the wavelength range of 520 to 640 nm of the transmission spectrum is set to 6% or less, or as described in JP-A-08-248201. It is also preferable that the difference in luminance of transmitted light at an arbitrary 1 cm distance on the film is within 30%.

(4) Durability (4-1) Damp heat durability As described in JP-A-2001-116922, the light transmittance before and after standing in an atmosphere of 60 ° C. and 90% RH for 500 hours and The rate of change in the degree of polarization is preferably 3% or less based on the absolute value. In particular, the light transmittance change rate is preferably 2% or less, and the polarization degree change rate is preferably 1.0% or less, more preferably 0.4% or less, based on the absolute value. Further, as described in JP-A-07-0777608, it is also preferable that the degree of polarization after standing at 80 ° C., 90% RH and 500 hours is 95% or more and the single transmittance is 38% or more.
(4-2) Dry durability It is preferable that the light transmittance and the rate of change of the degree of polarization before and after standing in a dry atmosphere at 80 ° C. for 500 hours are also 3% or less based on absolute values. In particular, the change rate of the light transmittance is preferably 2% or less, and the change rate of the polarization degree is preferably 1.0% or less, more preferably 0.1% or less based on the absolute value.

(4-3) Other Durability Further, as described in JP-A-06-167611, the shrinkage rate after leaving at 80 ° C. for 2 hours is 0.5% or less, or both surfaces of the glass plate The x and y values after leaving the polarizing plate laminate arranged in crossed Nicols in an atmosphere of 69 ° C. for 750 hours within the range described in JP-A-10-068818, or 80 ° C. and 90% range the change in spectral intensity ratio of the 105 cm ^-1 and 157cm ^-1, which is described in JP-a-08-094834 and JP 09-197127 by 200 hours standing after treatment of Raman spectroscopy in an atmosphere of RH It can also be preferably performed.

(5) Orientation degree The higher the degree of orientation of PVA, the better the polarization performance. However, the order parameter value calculated by means such as polarization Raman scattering or polarization FT-IR is preferably 0.2 to 1.0. It is. Further, as described in JP-A-59-133509, the difference between the orientation coefficient of the polymer segment in the entire amorphous region of the polarizing film and the orientation coefficient of the occupied molecule (0.75 or more) is at least 0. .15, or as described in JP-A-04-204907, the orientation coefficient of the amorphous region of the polarizing film is set to 0.65 to 0.85, or higher order iodine ions of I ₃ and I ₅ It is also preferable to set the degree of orientation to 0.8 to 1.0 as an order parameter value.

(6) Other characteristics As described in JP-A-2002-006133, the contraction force in the absorption axis direction per unit width when heated at 80 ° C. for 30 minutes is 4.0 N / cm or less. As described in Japanese Laid-Open Patent Publication No. 2002-236213, when the polarizing plate is placed under heating at 70 ° C. for 120 hours, the dimensional change rate in the absorption axis direction and the dimensional change rate in the polarization axis direction of the polarizing plate are In addition, it can be preferably carried out within a range of ± 0.6% or by setting the moisture content of the polarizing plate to 3% by mass or less as described in JP-A-2002-090546. Further, as described in Japanese Patent Laid-Open No. 2000-249832, the surface roughness in the direction perpendicular to the stretching axis is 0.04 μm or less based on the center line average roughness, or Japanese Patent Laid-Open No. 10-268294 discloses. As described, the refractive index n ₀ in the transmission axis direction should be larger than 1.6, or the relationship between the thickness of the polarizing plate and the thickness of the protective film should be in the range described in JP-A-10-111411. Can also be preferably performed.

4). Functionalization of Polarizing Plate The polarizing plate of the present invention includes an LCD optical compensation film (viewing angle widening film), a λ / 4 plate for application to a reflective LCD, an antireflection film for improving display visibility, and brightness. It is preferably used as a functionalized polarizing plate combined with an improvement film, an optical film having a functional layer such as a hard coat layer, a forward scattering layer, and an antiglare (antiglare) layer.
A configuration example in which the polarizing plate of the present invention and the above-described functional optical film are combined is shown in FIG. As a protective film on one side of the polarizing plate, a functional optical film may be adhered to the polarizing film via an adhesive (FIG. 3A), or an adhesive on a polarizing plate provided with protective films on both sides of the polarizing film. A functional optical film may be bonded via the substrate (FIG. 3B). In the former case, any transparent protective film can be used as the other protective film. The peel strength between layers such as a functional layer and a protective film is preferably 4.0 N / 25 mm or more described in JP-A No. 2002-311238. The functional optical film is preferably disposed on the liquid crystal module side according to the intended function, or on the side opposite to the liquid crystal module, that is, on the display side or the backlight side.

The functional optical film used in combination with the polarizing plate of the present invention will be described below.
(1) Optical Compensation Film The polarizing plate of the present invention is composed of TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensated Bend), VA (Vertically Aligned), ECB (Electrically Bold). It can be used in combination with an optical compensation film proposed for the mode (hereinafter referred to as a viewing angle widening film).

As a viewing angle widening film for TN mode, Journal of the Japan Printing Society Vol. 36, No. 3 (1999) p40-44, Monthly Display August (2002) p20-24, JP-A-4-229828, JP-A-6 -75115, JP-A-6-214116, JP-A-8-50206, JP-A-2001-100039 and the like, and preferably a combination of WV films manufactured by Fuji Photo Film Co., Ltd. used.
A preferred configuration of the viewing angle widening film for the TN mode has an alignment layer and an optically anisotropic layer in this order on the transparent polymer film. The viewing angle widening film is used by being bonded to a polarizing plate via an adhesive. At the same time, as described in SID'00 Dig., P551 (2000), it is particularly preferable from the viewpoint of thinning that the film is used also as one of the protective films of the polarizing film.

  The orientation layer of the viewing angle widening film can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound, and formation of a layer having a micro group. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. The rubbing treatment is preferably performed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. It is preferable that the absorption axis direction and the rubbing direction of the polarizing film are substantially parallel. As the polymer used for the alignment layer, polyimide, polyvinyl alcohol, a polymer having a polymerizable group described in JP-A-9-152509, and the like can be preferably used. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

  The optically anisotropic layer is preferably formed from a liquid crystalline compound. The liquid crystal compound used in the present invention particularly preferably has a discotic compound (discotic liquid crystal). The discotic liquid crystal molecule has a disk-like core portion like the following triphenylene derivative, and has a structure in which side chains extend radially therefrom. In order to impart stability over time, it is also preferable to further introduce a group that reacts with heat, light or the like. Preferred examples of the discotic liquid crystal are described in JP-A-8-50206.

Triphenylene derivative

  In the above structure, R represents a monovalent organic group having a polymerizable group such as an acryloyl group at the terminal.

  The discotic liquid crystal molecules are aligned almost parallel to the film plane with a pretilt angle in the rubbing direction in the vicinity of the alignment layer, and the discotic liquid crystal molecules are oriented so that they are perpendicular to the plane on the opposite air side. is doing. The discotic liquid crystal layer as a whole has a hybrid alignment, and this layer structure can realize a wide viewing angle of a TN mode TFT-LCD.

  The optically anisotropic layer is generally a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) dissolved in a solvent, coated on the alignment layer, dried, and then discotic nematic. After heating to the phase formation temperature, it is obtained by polymerization by irradiation with UV light or the like and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably 70 to 300 ° C, particularly preferably 70 to 170 ° C.

In addition to the discotic compound added to the optically anisotropic layer, the compound has compatibility with the discotic compound and can give a preferable change in tilt angle to the liquid crystalline discotic compound or inhibit the alignment. Any compound can be used as long as it is not. Among these, additives for controlling the orientation on the air interface side such as polymerizable monomers (eg, compounds having vinyl group, vinyloxy group, acryloyl group and methacryloyl group), fluorine-containing triazine compounds, cellulose acetate, cellulose acetate Mention may be made of polymers such as pionate, hydroxypropylcellulose and cellulose acetate butyrate. These compounds are generally used in an amount of 0.1 to 50% by mass, preferably 0.1 to 30% by mass, based on the discotic compound.
The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm.

  A preferred embodiment of the viewing angle widening film is composed of a cellulose acetate film as a transparent substrate film, an alignment layer provided thereon, and an optically anisotropic layer comprising a discotic liquid crystal formed on the alignment layer. The optically anisotropic layer is crosslinked by UV light irradiation.

  In addition to the above, when the viewing angle widening film and the polarizing plate of the present invention are combined, for example, as described in Japanese Patent Application Laid-Open No. 07-198942, it has an optical axis in a direction intersecting the plate surface. Lamination with a retardation plate exhibiting anisotropy in birefringence, or the dimensional change rate of the protective film and the optically anisotropic layer should be substantially the same as described in JP-A-2002-258052. Can also be preferably performed. Further, as described in JP-A No. 2000-258632, the moisture content of the polarizing plate bonded to the viewing angle widening film is set to 2.4% or less, or described in JP-A No. 2002-267839. It is also preferable to make the contact angle with water on the surface of the viewing angle widening film 70 ° or less.

  The viewing angle widening film for an IPS mode liquid crystal cell is used for optical compensation of liquid crystal molecules aligned in parallel to the substrate surface and for improving the viewing angle characteristics of the orthogonal transmittance of the polarizing plate during black display without an electric field. In the IPS mode, black is displayed when no electric field is applied, and the transmission axes of the pair of upper and lower polarizing plates are orthogonal. However, when observed from an oblique direction, the crossing angle of the transmission axes is not 90 °, and leakage light is generated, resulting in a decrease in contrast. When the polarizing plate of the present invention is used in an IPS mode liquid crystal cell, the in-plane retardation as described in JP-A-10-54982 is close to 0 and the thickness direction is reduced in order to reduce leakage light. It is preferably used in combination with a viewing angle widening film having a phase difference.

  The OCB mode viewing angle widening film for liquid crystal cells is intended to improve the viewing angle characteristics of black display by optically compensating the liquid crystal layer that is vertically aligned at the center of the liquid crystal layer by applying an electric field and tilted near the substrate interface. used. When the polarizing plate of the present invention is used in an OCB mode liquid crystal cell, it is preferably used in combination with a viewing angle widening film in which a discotic liquid crystalline compound as described in US Pat. No. 5,805,253 is hybrid-aligned.

  The viewing angle widening film for liquid crystal cells in the VA mode improves the viewing angle characteristics of black display in a state where liquid crystal molecules are vertically aligned with respect to the substrate surface in the absence of an electric field. As such a viewing angle widening film, a film having an in-plane retardation close to 0 and having a retardation in the thickness direction as described in Japanese Patent No. 2866372, or a discotic compound is used. A film arranged in parallel to the substrate, a film in which stretched films having the same in-plane retardation value are laminated so that the slow axes are orthogonal, and a liquid crystal to prevent the deterioration of orthogonal transmittance in the oblique direction of the polarizing plate It is preferably used in combination with a laminate of films made of rod-like compounds such as molecules.

(2) λ / 4 plate The polarizing plate of the present invention can be used as a circularly polarizing plate laminated with a λ / 4 plate. The circularly polarizing plate has a function of converting incident light into circularly polarized light, and is preferably used for a reflective liquid crystal display device, a transflective liquid crystal display device such as an ECB mode, or an organic EL element.
The λ / 4 plate used in the present invention is a retardation film having a retardation (Re) of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range. It is preferable that "Retardation of approximately 1/4 in the wavelength range of visible light" means that the longer the wavelength is from 400 to 700 nm, the larger the retardation, and the retardation value (Re450) measured at a wavelength of 450 nm is 80 to 125 nm. And the range which satisfies the relationship whose retardation value (Re590) measured by wavelength 590nm is 120 to 160 nm is shown. It is more preferable that Re590-Re450 ≧ 5 nm, and it is particularly preferable that Re590-Re450 ≧ 10 nm.

  The λ / 4 plate used in the present invention is not particularly limited as long as the above conditions are satisfied, but for example, described in JP-A-5-27118, JP-A-10-68816, and JP-A-10-90521. A λ / 4 plate obtained by laminating a plurality of polymer films, a λ / 4 plate obtained by stretching a single polymer film described in WO00 / 65384, WO00 / 26705, JP 2000-284126 A, A known λ / 4 plate such as a λ / 4 plate in which at least one optically anisotropic layer is provided on a polymer film described in JP-A-2002-31717 can be used. Moreover, the direction of the slow axis of the polymer film and the orientation direction of the optically anisotropic layer can be arranged in any direction according to the liquid crystal cell.

  In the circularly polarizing plate, the slow axis of the λ / 4 plate and the transmission axis of the polarizing film can intersect at an arbitrary angle, but preferably intersect within a range of 45 ° ± 20 °. However, the slow axis of the λ / 4 plate and the transmission axis of the polarizing film may intersect within a range other than the above.

  When the λ / 4 plate is formed by laminating the λ / 4 plate and the λ / 2 plate, as described in Japanese Patent No. 3236304 and Japanese Patent Laid-Open No. 10-68816, the λ / 4 plate and the λ / 4 plate / 2 It is preferable to bond the plate so that the angle formed by the slow axis in the plane of the plate and the transmission axis of the polarizing plate is substantially 75 ° and 15 °.

(3) Antireflection film The polarizing plate of the present invention can be used in combination with an antireflection film. As the antireflection film, either a film having a reflectivity of about 1.5% only by applying a single layer of a low refractive index material such as a fluoropolymer, or a film having a reflectivity of 1% or less using multilayer interference of thin films is used. it can. In the present invention, a structure in which a low refractive index layer and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a middle refractive index layer) is laminated on a transparent support is preferably used. The Further, an antireflection film described in Nitto Technical Report, vol. 38, No. 1, may, 2000, pages 26 to 28, JP-A-2002-301783, or the like can be preferably used.
The refractive index of each layer satisfies the following relationship.

  Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer

  As the transparent support used for the antireflection film, a transparent polymer film used for the protective film of the polarizing film can be preferably used.

The refractive index of the low refractive index layer is 1.20 to 1.55, preferably 1.30 to 1.50. The low refractive index layer is preferably used as an outermost layer having scratch resistance and antifouling properties. In order to improve the scratch resistance, it is also preferable to impart slipperiness to the surface using a material containing a silicone group or fluorine.
Examples of the fluorine-containing compound include JP-A-9-222503, paragraphs [0018] to [0026], paragraphs [0019] to [0030] of JP-A-11-38202, and paragraphs of JP-A-2001-40284. Nos. [0027] to [0028], and compounds described in JP-A No. 2000-284102 and the like can be preferably used.
The silicone-containing compound is preferably a compound having a polysiloxane structure, but reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane at both ends (Japanese Patent Laid-Open No. 11-258403), etc. An organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent may be cured by a condensation reaction in the presence of a catalyst (Japanese Patent Laid-Open No. 58-142958). Gazettes, 58-147483, 58-147484, JP-A-9-157582, 11-106704, JP-A-2000-117902, 2001-48590, 2002-2002. 53804).
The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as fillers (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as additives other than the above. Inorganic compounds having a low refractive index, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820), silane coupling agents, slip agents, surfactants, and the like are preferably added. be able to.
The low refractive index layer may be formed by a vapor phase method (vacuum vapor deposition method, sputtering method, ion plating method, plasma CVD method, etc.), but is preferably formed by a coating method because it can be manufactured at low cost. . As the coating method, dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and micro gravure can be preferably used.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

The medium refractive index layer and the high refractive index layer preferably have a constitution in which ultrafine particles of high refractive index having an average particle size of 100 nm or less are dispersed in a matrix material. Inorganic compound fine particles having a high refractive index include inorganic compounds having a refractive index of 1.65 or more, for example, oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and metal atoms thereof. A composite oxide or the like can be preferably used.
For such ultrafine particles, the surface of the particles is treated with a surface treatment agent (silane coupling agent, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908, etc.) Compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432), a core-shell structure with high refractive index particles as a core (Japanese Patent Laid-Open No. 2001-166104, etc.), or a specific dispersant is used in combination. (For example, Japanese Patent Application Laid-Open No. 11-153703, European Patent No. 6210858B1, Japanese Patent Application Laid-Open No. 2002-27776069, etc.) can be applied.

As the matrix material, conventionally known thermoplastic resins, curable resin films, and the like can be used. Furthermore, JP-A 2000-47004, 2001-315242, 2001-31871, 2001-296401. It is also possible to use a curable film obtained from a polyfunctional material described in JP-A-2001-293818 or a metal alkoxide composition described in JP-A-2001-293818.
The refractive index of the high refractive index layer is preferably 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K 5400.

(4) Brightness improving film The polarizing plate of this invention can be used in combination with a brightness improving film. The brightness enhancement film has a function of separating circularly polarized light or linearly polarized light, and is disposed between the polarizing plate and the backlight, and reflects or scatters one circularly polarized light or linearly polarized light back to the backlight side. Re-reflected light from the backlight part partially changes the polarization state and partially transmits when re-entering the brightness enhancement film and the polarizing plate, so the light utilization rate is improved by repeating this process. The front luminance is improved to about 1.4 times. As the brightness enhancement film, an anisotropic reflection system and an anisotropic scattering system are known, and both can be combined with the polarizing plate of the present invention.

  In the anisotropic reflection system, a brightness enhancement film having anisotropy in reflectance and transmittance is known by laminating a uniaxially stretched film and an unstretched film in multiple layers and increasing the refractive index difference in the stretching direction. Multilayer film systems using the principle of dielectric mirrors (described in the specifications of WO95 / 17691, WO95 / 17692, WO95 / 17699) and cholesteric liquid crystal systems (European Patent No. 606940A2, Japanese Patent Laid-Open No. Hei 8- No. 271731) is known. DBEF-E, DBEF-D, and DBEF-M (all manufactured by 3M) are used as multi-layer brightness enhancement films using the principle of dielectric mirrors, and NIPOCS (Nitto Denko Corporation) as a cholesteric liquid crystal brightness enhancement film. )) Is preferably used in the present invention. Regarding NIPOCS, Nitto Giho, vol.38, No.1, may, 2000, pages 19-21 can be referred to.

  Further, in the present invention, positive numbers described in the specifications of WO97 / 32223, WO97 / 32224, WO97 / 32225, WO97 / 32226 and JP-A-9-274108 and 11-174231 are described. It is also preferable to use it in combination with a brightness enhancement film of an anisotropic scattering method in which an intrinsic birefringent polymer and a negative intrinsic birefringent polymer are blended and uniaxially stretched. As the anisotropic scattering system brightness enhancement film, DRPF-H (manufactured by 3M) is preferable.

  The polarizing plate and the brightness enhancement film of the present invention are preferably used as a form bonded with an adhesive or an integrated form in which one of the protective films of the polarizing plate is a brightness enhancement film.

(5) Other functional optical films The polarizing plate of the present invention further includes a hard coat layer, a forward scattering layer, an antiglare (antiglare) layer, a gas barrier layer, a sliding layer, an antistatic layer, an undercoat layer, a protective layer, and the like. It is also preferable to use it in combination with a functional optical film having a functional layer. These functional layers are preferably used in combination with each other or in the same layer as the above-described antireflection layer, optically anisotropic layer, or the like.

(5-1) Hard Coat Layer In order to impart mechanical strength such as scratch resistance to the polarizing plate of the present invention, the hard coat layer may be combined with a functional optical film provided on the surface of the transparent support. preferable. When the hard coat layer is applied to the above-described antireflection film and used, it is particularly preferable to provide it between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of the curable compound by light and / or heat. As the curable functional group, a photopolymerizable functional group is preferable. As a specific constituent composition of the hard coat layer, for example, those described in JP-A Nos. 2002-144913, 2000-9908 and WO0 / 46617 can be preferably used.
The film thickness of the hard coat layer is preferably 0.2 to 100 μm.
The strength of the hard coat layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K 5400. Further, in the Taber test according to JIS K 5400, the smaller the wear amount of the test piece before and after the test, the better.

Examples of the material for forming the hard coat layer include a compound containing an ethylenically unsaturated group and a compound containing a ring-opening polymerizable group, and these compounds can be used alone or in combination.
Preferred examples of the compound containing an ethylenically unsaturated group include ethylene glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol. Polyacrylates of polyols such as hexaacrylate; epoxy acrylates such as diacrylate of bisphenol A diglycidyl ether, diacrylate of hexanediol diglycidyl ether; obtained by reaction of polyisocyanate and hydroxyl group-containing acrylate such as hydroxyethyl acrylate Examples of preferred compounds include urethane acrylates.
Moreover, as a commercially available compound, EB-600, EB-40, EB-140, EB-1150, EB-1290K, IRR214, EB-2220, TMPTA, TMPTMA (above, Daicel UCB Co., Ltd. product), UV -6300, UV-1700B (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and the like.
Preferred examples of the compound containing a ring-opening polymerizable group include glycidyl ethers such as ethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl. Ethers, triglycidyl trishydroxyethyl isocyanurate, sorbitol tetraglycidyl ether, pentaerythritol tetraglycyl ether, polyglycidyl ether of cresol novolac resin, polyglycidyl ether of phenol novolac resin, etc .; , Epolido GT-301, Epolide GT-401, EHPE3150CE , Manufactured by Daicel Chemical Industries, Ltd.), polycyclohexyl epoxy methyl ether of phenol novolac resin, etc .; as oxetanes, OXT-121, OXT-221, OX-SQ, PNOX-1009 (above, manufactured by Toagosei Co., Ltd.) Etc.
In addition, a polymer of glycidyl (meth) acrylate or a copolymer of a monomer that can be copolymerized with glycidyl (meth) acrylate can be used for the hard coat layer.

  In the hard coat layer, in order to reduce curing shrinkage of the hard coat layer, improve adhesion to the substrate, and reduce curling of the hard coat treated article of the present invention, metal atoms such as silicon, titanium, zirconium, aluminum, etc. Oxide fine particles: It is also preferable to add cross-linked fine particles such as cross-linked particles such as polyethylene, polystyrene, poly (meth) acrylic esters, polydimethylsiloxane, and organic fine particles such as cross-linked rubber fine particles such as SBR and NBR. These crosslinked fine particles preferably have an average particle size of 1 nm to 20000 nm. Further, the shape of the crosslinked fine particles can be used without particular limitation, such as a spherical shape, a rod shape, a needle shape, or a plate shape. The addition amount of the fine particles is preferably 60% by volume or less, more preferably 40% by volume or less of the hard coat layer after curing.

  When the inorganic fine particles described above are added, since they generally have poor affinity with the binder polymer, they contain metal atoms such as silicon, aluminum, titanium, etc., and alkoxide groups, carboxylic acid groups, sulfonic acid groups, phosphonic acid groups It is also preferable to perform a surface treatment using a surface treatment agent having a functional group such as.

  The hard coat layer is preferably cured using heat or active energy rays. Among them, active energy rays such as radiation, gamma rays, alpha rays, electron rays, and ultraviolet rays are more preferred, and safety and productivity are improved. In view of the above, it is particularly preferable to use an electron beam or an ultraviolet ray. In the case of curing with heat, the heating temperature is preferably 140 ° C. or less, more preferably 100 ° C. or less, considering the heat resistance of the plastic itself.

(5-2) Forward scattering layer The forward scattering layer is used to improve the viewing angle characteristics (hue and luminance distribution) in the vertical and horizontal directions when the polarizing plate of the present invention is applied to a liquid crystal display device. In the present invention, a configuration in which fine particles having different refractive indexes are dispersed in a binder is preferable. For example, Japanese Patent Laid-Open No. 11-38208 in which the forward scattering coefficient is specified, and the relative refractive index of the transparent resin and the fine particles is in a specific range. 2000-199809 gazette, Unexamined-Japanese-Patent No. 2002-107512 etc. which prescribed | regulated the haze value as 40% or more can be used.
Moreover, in order to control the viewing angle characteristics of the haze of the polarizing plate of the present invention, it is also preferable to use it in combination with “Lumistic” described in Sumitomo Chemical's technical report “Optical Functional Film” on pages 31-39.

(5-3) Antiglare layer The antiglare (antiglare) layer is used to scatter reflected light and prevent reflection. The antiglare function is obtained by forming irregularities on the outermost surface (display side) of the liquid crystal display device. The haze of the optical film having an antiglare function is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.
The method for forming irregularities on the film surface is, for example, a method of forming irregularities on the film surface by adding fine particles (for example, JP-A No. 2000-271878), relatively large particles (particle size 0.05-2 μm). ) Is added in a small amount (0.1 to 50% by mass) (for example, Japanese Patent Application Laid-Open Nos. 2000-281410, 2000-95893, 2001-100004, and 2001). 281407, etc.), and a method for physically transferring the uneven shape onto the film surface (for example, embossing methods are disclosed in JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401). Etc.) can be preferably used.

  These functional layers can be used by being provided on one side or both sides of the surface on the polarizing film side and the surface opposite to the polarizing film.

5. Next, a liquid crystal display device using the polarizing plate of the present invention will be described.
FIG. 2 is an example of a liquid crystal display device in which the polarizing plate of the present invention is used.

  The liquid crystal display device shown in FIG. 2 includes a liquid crystal cell (105 to 109), and an upper polarizing plate 101 and a lower polarizing plate 112 which are disposed so as to sandwich the liquid crystal cell (105 to 109). The polarizing plate is sandwiched between a polarizing film and a pair of transparent protective films, but is shown as an integrated polarizing plate in FIG. The liquid crystal cell includes a liquid crystal layer formed of an upper substrate 105 and a lower substrate 108 and liquid crystal molecules 107 sandwiched therebetween. The liquid crystal cell is different in the alignment state of liquid crystal molecules that perform ON / OFF display. However, the polarizing plate of the present invention can be used in any display mode regardless of the transmissive and reflective types.

  An alignment film (not shown) is formed on the surfaces of the substrates 105 and 108 that are in contact with the liquid crystal molecules 107 (hereinafter may be referred to as “inner surfaces”), and by a rubbing process or the like applied on the alignment film, The alignment of the liquid crystal molecules 107 in a state where no electric field is applied or a state where a low voltage is applied is controlled. Further, on the inner surfaces of the substrates 105 and 108, a transparent electrode (not shown) capable of applying an electric field to the liquid crystal layer made of the liquid crystal molecules 107 is formed.

The rubbing direction of the TN mode is applied in directions orthogonal to each other on the upper and lower substrates, and the magnitude of the tilt angle can be controlled by the strength and the number of rubbing. The alignment film can be formed by applying and baking a polyimide film. The magnitude of the twist angle (twist angle) of the liquid crystal layer is determined by the crossing angle of the upper and lower substrates in the rubbing direction and the chiral agent added to the liquid crystal material. Here, a chiral agent having a pitch of about 60 μm was added so that the twist angle was 90 °.
The twist angle is about 90 ° (85 to 95 °) in the case of a notebook computer, a personal computer monitor, and a liquid crystal display device for a TV, and 0 to 70 ° when used as a reflective display device such as a cellular phone. Set. In the IPS mode and ECB mode, the twist angle is 0 °. In the IPS mode, electrodes are disposed only on the lower substrate 108, and an electric field parallel to the substrate surface is applied. Further, in the OCB mode, there is no twist angle and the tilt angle is increased, and in the VA mode, the liquid crystal molecules 107 are aligned perpendicular to the upper and lower substrates.

Here, the magnitude of the product Δnd of the thickness d of the liquid crystal layer and the refractive index anisotropy Δn changes the brightness during white display. Therefore, in order to obtain the maximum brightness, the range is set for each display mode.
In general, the crossing angle between the absorption axis 102 of the upper polarizing plate 101 and the absorption axis 113 of the lower polarizing plate 112 is generally orthogonally crossed to obtain high contrast. The crossing angle between the absorption axis 102 of the upper polarizing plate 101 of the liquid crystal cell and the rubbing direction of the upper substrate 105 depends on the liquid crystal display mode, but is generally set to be parallel or vertical in the TN and IPS modes. In OCB and ECB modes, it is often set to 45 °. However, the optimum value differs in each display mode for adjusting the color tone and viewing angle of the display color, and the present invention is not limited to this range.

  The liquid crystal display device in which the polarizing plate of the present invention is used is not limited to the configuration of FIG. 2, and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. In addition, the aforementioned viewing angle widening films (optically anisotropic layers) 103 and 110 can be separately disposed between the liquid crystal cell and the polarizing plate. The polarizing plates 101 and 113 and the viewing angle widening films 103 and 110 may be arranged in a laminated form bonded with an adhesive, or a so-called integrated elliptical polarization using one of the liquid crystal cell side protective films for widening the viewing angle. It may be arranged as a plate.

  When used as a transmission type, a cold cathode or hot cathode fluorescent tube, or a backlight having a light emitting diode, field emission element, or electroluminescent element as a light source can be disposed on the back surface. Further, the liquid crystal display device in which the polarizing plate of the present invention is used may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and the back of the liquid crystal cell or under the liquid crystal cell. A reflective film is installed on the inner surface of the side substrate. Of course, a front light using the light source may be provided on the liquid crystal cell observation side.

  In order to describe the present invention specifically, the following examples will be described. However, the present invention is not limited to these examples.

[Comparative Example 1: Production of Polarizing Plate P-1]
A PVA film having an average degree of polymerization of 2400 and a film thickness of 125 μm is pre-swelled with ion exchange water at 15 ° C. for 15 seconds, and after scraping the surface moisture with a stainless steel blade, the concentration of the PVA film becomes constant. As described above, the sample was immersed in an aqueous solution (staining solution) of 1.0 g / L of iodine and 60.0 g / L of potassium iodide at 40 ° C. for 85 seconds, and the concentration was corrected so that the concentration was constant. After dipping in an aqueous solution (hardening solution) of boric acid 42.5 g / L and potassium iodide 30 g / L at 55 ° C. for 90 seconds, both surfaces of the film were scraped with a stainless steel blade to remove excess moisture. It was introduced into a tenter drawing machine. After feeding 100m at a conveyance speed of 4m / min and stretching up to 4.12 times in a 98 ° C 98% atmosphere, the tenter is bent in the stretching direction as shown in Fig. 1, and then the width is kept constant and contracted. However, it was removed from the tenter after drying in an atmosphere at 67 ° C. At this time, the polarizing film had a thickness of 29 μm and a moisture content of 4.0%. Then, 3 cm from the width direction, after cutting with a cutter, Fujitac (cellulose triacetate, manufactured by Fuji Photo Film Co., Ltd.), which was saponified using a 3% aqueous solution of PVA (PVA-124H manufactured by Kuraray Co., Ltd.) as an adhesive. In-plane retardation value 3.0 nm, film thickness 80 μm), and further heated at 70 ° C. for 10 minutes to produce roll-type polarizing plate P-1 having an effective width of 650 mm and a length of 100 m.
About this polarizing plate, the transmittance | permeability at the time of 410 nm crossed Nicols was measured with Shimadzu self-recording spectrophotometer UV3100.
The degree of polarization P is expressed by the following equation, where the transmittance when two polarizing plates are overlapped with the absorption axis aligned is H0 (%), and the transmittance when the absorption axes are stacked orthogonally is H1 (%). Determined by
The single plate transmittance and polarization degree were corrected for visibility.
P = ((H0−H1) / (H0 + H1)) ^1/2 × 100
The content of boric acid in the polarizing film was measured by atomic absorption, and the thickness of the polarizing film was examined by a contact type film thickness meter.
The polarization degree change ΔP after the polarizing plate P-1 was allowed to stand for 24 hours at 80 ° C. and 90% was measured and used as an index of durability.
ΔP = initial polarization degree−polarization degree after standing at 80 ° C. and 90% for 24 hours. These results are shown in Table 1.

[Comparative Examples 2 to 5: Production of polarizing plates P-2 to P-5]
The thickness of the PVA film, the hardening solution temperature, the draw ratio, the dilution of the dye solution with ion-exchanged water, and the dye solution immersion time were changed as shown in Table 1, and in the same manner as in Comparative Example 1, the polarizing plate P-2 -P-5 was produced.
The same measurements as in Comparative Example 1 were performed, and the results are summarized in Table 1.

[Comparative Example 6: Production of polarizing plate P-6]
A polarizing plate P-6 was produced in the same manner as in Comparative Example 3 except that the film was uniaxially stretched using a tenter stretching machine.
The same measurements as in Comparative Example 1 were performed, and the results are summarized in Table 1.

[Comparative Example 7: Polarizing plate P-7]
A polarizing plate (SEG1425DU) manufactured by Nitto Denko Corporation was designated as polarizing plate P-7. About this, the same measurement as the comparative example 1 was performed, and the result was put together in Table 1.

  From Table 1, it can be seen that the durability deteriorates as the polarizing plate is thinned.

[Example 1: Production of polarizing plate P-8]
A polarizing plate P-8 was produced in the same manner as in Comparative Example 2 except that the boric acid solution was an aqueous solution of boric acid 42.5 g / L and potassium iodide 3 g / L, and dipped at 50 ° C. for 90 seconds.
The film thickness at this time was 24 μm, the boric acid content per unit volume was 205 kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.06%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.11%.

[Example 2: Production of polarizing plate P-9]
A polarizing plate P-9 was prepared in the same manner as in Comparative Example 3 except that the boric acid solution was 42.5 g / L boric acid, 3 g / L potassium iodide aqueous solution, 0.05 g / L iodine, and immersion at 55 ° C. for 90 seconds. Produced.
The film thickness at this time was 19 μm, the boric acid content per unit volume was 235 Kg / m ³ , and the crossed Nicols transmittance at 410 nm was 0.06%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.10%.

[Example 3: Production of polarizing plate P-10]
A polarizing plate P-10 was prepared in the same manner as in Comparative Example 4, except that the boric acid solution was boric acid 42.5 g / L, potassium iodide 3 g / L aqueous solution, iodine 0.05 g / L, and immersion for 90 seconds at 50 ° C. Produced.
The film thickness at this time was 17.5 μm, the boric acid content per unit volume was 240 kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.12%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.12%.

[Example 4: Production of polarizing plate P-11]
A polarizing plate P-11 was prepared in the same manner as in Comparative Example 5 except that the boric acid solution was boric acid 42.5 g / L, potassium iodide 4 g / L aqueous solution, iodine 0.05 g / L, and immersion was performed at 50 ° C. for 90 seconds. Produced.
The film thickness at this time was 14 μm, the boric acid content per unit volume was 240 Kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.08%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.10%.

[Example 5: Production of polarizing plate P-12]
A polarizing plate P-12 was prepared in the same manner as in Comparative Example 5, except that the boric acid solution was boric acid 42.5 g / L, potassium iodide 4 g / L aqueous solution, iodine 0.05 g / L, and immersion at 50 ° C. for 90 seconds. Produced.
The film thickness at this time was 14 μm, the boric acid content per unit volume was 240 Kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.08%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.10%.

[Example 6: Production of polarizing plate P-13]
A polarizing plate P-13 was prepared in the same manner as in Comparative Example 5 except that the boric acid solution was boric acid 42.5 g / L, potassium iodide 4 g / L aqueous solution, iodine 0.05 g / L, and immersion was performed at 55 ° C. for 90 seconds. Produced.
The film thickness at this time was 14 μm, the boric acid content per unit volume was 275 Kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.08%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.11%.

[Example 7: Production of polarizing plate P-14]
A polarizing plate P-14 was prepared in the same manner as in Comparative Example 5 except that the boric acid solution was boric acid 42.5 g / L, potassium iodide 4 g / L aqueous solution, iodine 0.05 g / L, and immersion at 55 ° C. for 120 seconds. Produced.
The film thickness at this time was 14 μm, the boric acid content per unit volume was 295 Kg / m ³ , and the crossed Nicol transmittance at 410 nm was 0.08%.
Further, the change in polarization degree ΔP after 24 hours under the condition of 80 ° C. and 90% was 0.10%.

  These results are summarized in Table 2.

Next, an example of a liquid crystal panel combined with an optical compensation sheet will be described as an example.
[Example 6]
(Production of cellulose acetate film)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

<Cellulose acetate solution composition>
Cellulose acetate having an acetylation degree of 60.9% 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (No. 1) 2 solvents) 54 parts by mass 1-butanol (third solvent) 11 parts by mass

  In another mixing tank, 16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution. A dope was prepared by mixing 474 parts by mass of a cellulose acetate solution with 25 parts by mass of a letter-raising agent solution and stirring sufficiently. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.

  The obtained dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried with warm air of 70 ° C. for 1 minute, and the film was peeled off from the band. Subsequently, the film was dried with a drying air at 140 ° C. for 10 minutes to produce a cellulose acetate film (thickness: 50 μm) having a residual solvent amount of 0.3% by mass. The produced cellulose acetate film was immersed in a 2.0N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water and dried. The surface energy of this cellulose acetate film was determined by a contact angle method and found to be 63 mN / m. The Re retardation value measured at a wavelength of 546 nm was 4 nm.

(Formation of alignment film)
On the produced cellulose acetate film, a coating solution for forming an alignment film having the following composition was applied at 28 ml / m ² with a # 16 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds. Next, the formed film was rubbed in a direction parallel to the longitudinal direction of the cellulose acetate film.

<Alignment film coating solution composition>
Modified polyvinyl alcohol having the following structure 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight

(Formation of optically anisotropic layer)
On the alignment film, 41.01 g of a discotic compound (discotic (liquid crystal) compound) having the following structure, 4.06 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose Acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Company) 0.90 g, cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Company) 0.23 g, photopolymerization initiator (Irgacure 907, Ciba Geigy Company) A coating solution prepared by dissolving 1.35 g (manufactured) and 0.45 g sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) in 102 g of methyl ethyl ketone was coated with a # 3.6 wire bar. This was heated in a constant temperature zone of 130 ° C. for 2 minutes to orient the discotic compound. Next, UV irradiation was performed for 1 minute using a 120 W / cm high pressure mercury lamp in an atmosphere of 60 ° C. to polymerize the discotic compound. Then, it stood to cool to room temperature. Thus, an optically anisotropic layer was formed, and an optical compensation sheet (KH-01) was produced. The Re retardation value of the optically anisotropic layer measured at a wavelength of 546 nm was 43 nm. The angle (tilt angle) between the disk surface and the first transparent support surface was 42 ° on average.

  Using the polyvinyl alcohol-based adhesive, the optical compensation sheet (KH-01) prepared above is attached to one side of the polarizing film so that the cellulose acetate film is on the polarizing film side. It was. The transmission axis of the polarizing film and the slow axis of the optical compensation sheet (KH-01) were arranged in parallel. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to saponification treatment and attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. In this way, a polarizing plate was produced.

  A pair of polarizing plates provided in a 20-inch liquid crystal display device (LC-20V1, manufactured by Sharp Corporation) composed of a TN type liquid crystal cell is peeled off, and instead of the polarizing plate produced above, an optical compensation sheet (KH One sheet was affixed to the viewer side and the backlight side through an adhesive so that -01) was on the liquid crystal cell side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged so as to be orthogonal to each other. Under the environmental conditions of a temperature of 25 ° C. and a relative humidity of 60%, the backlight was lit continuously for 5 hours, and the entire black display state was visually observed in a dark room to evaluate light leakage. As a result, no light leakage was observed on the display screen of the liquid crystal display device.

In Comparative Example 1, it is a schematic plan view showing a method and apparatus for obliquely stretching a polymer film in order to produce a polarizing film. 1 is a schematic sketch showing a liquid crystal display device of the present invention. It is a schematic sectional drawing which shows the example which combined the polarizing plate and functional optical film of this invention. (A) is an example in which a functional optical film is bonded to a polarizing film via an adhesive as a protective film on one side of the polarizing plate, and (B) is an adhesive on a polarizing plate provided with protective films on both sides of the polarizing film. This is an example in which a functional optical film is bonded via

Explanation of symbols

(A) Film introduction direction (b) Film transport direction to the next step (a) Step of introducing the film (b) Step of stretching the film (c) Step of sending the stretched film to the next step A1 To the means for holding the film Biting position and starting point of film stretching (actual holding start point: right)
B1 Biting position of film holding means (left)
C1 Film stretch starting position (substantially holding start point: left)
Cx film release position and film stretching end point reference position (substantially holding release point: left)
Ay Film drawing end point reference position (substantially holding release point: right)
| L1-L2 | Stroke difference W between left and right film holding means Substantially width θ at the end of the film stretching process 21 Angle formed by the stretching direction and the film traveling direction Center line 22 of the introduction side film Center line 23 of the film sent to the next process Trajectory of film holding means (left)
24 Trajectory of film holding means (right)
25 Introduction-side film 26 Films 27 and 27 ′ sent to the next process Left and right film holding start (biting) points 28 and 28 ′ Left and right film holding points 101 Upper polarizing plate 102 Upper polarizing plate Absorption axis 103 Upper Optical anisotropic layer 104 Upper optical anisotropic layer alignment control direction 105 Liquid crystal cell upper electrode substrate 106 Upper substrate alignment control direction 107 Liquid crystal layer 108 Liquid crystal cell lower electrode substrate 109 Lower substrate alignment control direction 110 Lower optical anisotropic layer 111 Lower optical anisotropic layer orientation control direction 112 Lower polarizing plate 113 Lower polarizing plate absorption axis

Claims (12)

The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.14%, the boric acid content per volume of the polarizing film is 200 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. A polarizing plate having a thickness of 25 μm or less. The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.19%, the boric acid content per volume of the polarizing film is 230 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. A polarizing plate having a thickness of 25 μm or less. 2. The polarizing plate according to claim 1, wherein the transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.10%, and the thickness of the polarizing film is 5 μm or more and 22 μm or less. The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.16%, the boric acid content per volume of the polarizing film is 260 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is 5 μm. The polarizing plate according to claim 2, wherein the polarizing plate is 22 μm or more. The transmittance at 410 nm at the time of crossed Nicols is 0 or more and less than 0.10%, the boric acid content per volume of the polarizing film is 230 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is It is 5 micrometers or more and 20 micrometers or less, The polarizing plate of Claim 1 characterized by the above-mentioned. The transmittance at 410 nm in crossed Nicols is 0 or more and less than 0.14%, the boric acid content per volume of the polarizing film is 290 kg / m ³ or more and 480 kg / m ³ or less, and the film thickness of the polarizing film is It is 5 micrometers or more and 20 micrometers or less, The polarizing plate of Claim 2 characterized by the above-mentioned. The polarizing plate according to claim 1, wherein the single plate transmittance is 42% or more and the degree of polarization is 99.9% or more. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein at least one of the transparent protective films is made of a cellulose acetate film and has a thickness in the range of 10 to 70 μm. The polarizing plate according to any one of claims 1 to 7. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof,
One of the transparent protective films is a cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of the cellulose acetate. An optical compensation sheet comprising an optically anisotropic layer formed from a liquid crystalline compound on a cellulose acetate film containing 0.01 to 20 parts by mass, and is defined by the following mathematical formula (1) of the cellulose acetate film. The Re retardation value is in the range of 0 to 20 nm, the Rth retardation value defined by the following formula (2) is in the range of 70 to 400 nm, and the thickness is in the range of 10 to 70 μm. The polarizing plate according to claim 8.
Formula (1): Re = (nx−ny) × d
Formula (2): Rth = {(nx + ny) / 2−nz} × d
[In the above formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the refractive index in the thickness direction of the film. And d is the thickness of the film]. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof,
One of the transparent protective films is a cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of the cellulose acetate. An optical compensation sheet comprising an optically anisotropic layer formed from a liquid crystalline compound on a cellulose acetate film containing 0.01 to 20 parts by mass, and is defined by the following mathematical formula (1) of the cellulose acetate film. The Re retardation value is in the range of 0 to 20 nm, the Rth retardation value defined by the following formula (2) is in the range of 0 to 40 nm, and the thickness is in the range of 10 to 70 μm. The polarizing plate according to claim 8.
Formula (1): Re = (nx−ny) × d
Formula (2): Rth = {(nx + ny) / 2−nz} × d
[In the above formula, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, and nz is the refractive index in the thickness direction of the film. And d is the thickness of the film]. The polarizing plate according to claim 9 or 10, wherein the Re retardation value is in the range of 0 to 5 nm. A liquid crystal display device using the polarizing plate according to claim 1 for at least one of two polarizing plates arranged on both sides of a liquid crystal cell.

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