KR20160092985A - High-contrast polarization element exhibiting uniform transmittance at respective wavelengths, and polarization plate - Google Patents

Abstract

...식(1)
(식(1) 중, R₁은 수소원자, 할로겐 원자, 저급 알킬기, 저급 알콕시기, 또는 카복시기를 나타내고, k, m, n은 각각 0 또는 1을 나타낸다. 단, m+n>1이다)
으로 표시되는 유기 화합물 또는 그의 염을 함유하고,
상기 기재를 단체로 측정한 경우의 시감도보정 단체투과율 Ys이 40.0% 내지 42.5%이고,
시감도보정 단체투과율 Ys과 460nm의 단체투과율 Ts₄₆₀과의 차가 1.2% 이내이며,
시감도보정 단체투과율 Ys과 550nm의 단체투과율 Ts₅₅₀과의 차가 1% 이내이고,
시감도보정 단체투과율 Ys과 610nm의 단체투과율 Ts₆₁₀과의 차가 1% 이내이며,
상기 기재 2매를 흡수축 방향에 대하여 직교되게 하여 측정한 경우의 시감도보정 직교투과율이 0.01% 이하이고,
상기 기재 2매를 흡수축 방향에 대하여 직교되게 하여 측정한 경우의 430nm 내지 480nm의 직교투과율의 평균치 Tc Ave430-480이 0.03% 이하인 것을 특징으로 하는, 편광소자.[PROBLEMS] The polarizing element of the present invention provides a polarizing element and a polarizing plate having a substantially constant transmittance at each wavelength transmittance and a high contrast in the cases where the polarizing elements are arranged parallel to the absorption axis and in the case of being arranged orthogonally .
[MEANS FOR SOLVING PROBLEMS] A polarizing element comprising a hydrophilic polymer drawn by adsorbing boric acid and containing a substrate having a polarizing function and containing iodine,

... (1)
(1), R ₁ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and k, m and n each represent 0 or 1, provided that m + n>
Or a salt thereof,
The visual sensitivity-corrected single-unit transmittance Ys when the base material is measured in a single body is 40.0% to 42.5%
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the unitary transmittance Ts ₄₆₀ of ₄₆₀ nm is 1.2% or less,
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₅₅₀ of ₅₅₀ nm is within 1%
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₆₁₀ of ₆₁₀ nm is within 1%
The visibility-corrected orthogonal transmittance of the two substrates is measured to be orthogonal to the absorption axis direction of not more than 0.01%
Wherein an average value of the orthogonal transmittances Tc Ave 430 to 480 of 430 to 480 nm when the two substrates are measured perpendicular to the absorption axis direction is 0.03% or less.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high contrast polarizing element and a polarizing plate having a uniform transmittance at each wavelength,

The present invention relates to a polarizing element and a polarizing plate having a uniform transmittance at each wavelength and having high contrast.

The polarizing element is generally produced by adsorbing and orienting iodine or a dichroic dye, which is a dichroic dye, on a polyvinyl alcohol resin film. A protective film including triacetyl cellulose or the like is bonded to at least one side of the polarizing element through an adhesive layer to form a polarizing plate and is used for a liquid crystal display device or the like. A polarizing plate using iodine as a dichroic dye is called an iodine polarizing plate and a polarizing plate using a dichroic dye as a dichroic dye is called a dye-based polarizing plate. Among these, the dye-based polarizing plate is characterized by high heat resistance, high damp heat durability, high stability, and high color selectivity by blending. On the other hand, compared with the iodine type polarizing plate having the same degree of polarization, There was a low problem. If the polarizing elements so far provided parallel to the absorption axis and exhibited white color, the transmittance of 380 nm to 480 nm was lower than that of 500 nm to 600 nm, and uniformity of light emission at each wavelength was not guaranteed. Thus, for example, when the absorption axis of the polarizing element is provided in parallel, an attempt has been made to improve the transmittance of each wavelength to have a constant transmittance. However, even in this case, there is a problem that the contrast is lowered because a wavelength of 380-480 nm, especially a wavelength of 460 nm, is higher than a transmissivity of about 550 nm, which is high in visibility in the case of providing an orthogonal axis with respect to the absorption axis. Therefore, a polarizing element or a polarizing plate has been required as a polarizing element or a polarizing plate capable of maintaining a high polarizing performance, that is, a high contrast and a constant transmittance of each wavelength in the visible region.

Patent Document 1: JP-A-2005-49698 Patent Document 2: JP-A-2005-202367

Non-Patent Document 1: Application of Functional Dyes First Edition Publishing Co., Ltd. CMC Publishing Irie Masahiro supervision, P98-100

A method of making the transmittance of the polarizing plate constant at each wavelength is disclosed in, for example, Patent Document 1 or Patent Document 2. Patent Document 1 discloses a technique of a polarizing element having a transmittance of 0.001% to 0.1% at a cross-nicol of 410 nm in a polarizing element having a film thickness of 8 to 18 탆. However, the above technique improves color separation and color on the orthogonal 410 nm and improves the transmittance of each wavelength on a parallel line. In a liquid crystal display device designed with a backlight of a recent LED light source, Since almost 430 nm to 480 nm of blue light emitted from 460 nm to the bright line is the main emission light source, the contrast of 410 nm is almost not required. Therefore, in order to improve the contrast, it was necessary to improve the contrast of the wavelength of 430 to 480 nm. The prescription of Patent Document 1 does not provide sufficient contrast to be used in a display device when a backlight such as an LED light source or the like is used to improve the color of the flat behavior. Patent Document 2 discloses a technique of a polarizing element including a film in which minute domains are dispersed in a matrix formed by a water-soluble resin containing a divalent metal. However, according to the technique, a polarizing element or a polarizing plate having a constant transmittance of each wavelength on the parallel line and the orthogonal line has not been obtained.

Means for Solving the Problems The present inventors have intensively studied to solve the above problems and have completed the present invention.

That is,

(1) A polarizing element comprising a substrate having a polarizing function and containing iodine, which comprises a hydrophilic polymer drawn by adsorbing boric acid,

In the form of free acid, formula (1):

...(1)

...(One)

(1), R ₁ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and k, m and n each represent 0 or 1, provided that m + n>

Or a salt thereof,

The visual sensitivity-corrected single-unit transmittance Ys when the base material is measured in a single body is 40.0% to 42.5%

The difference between the visibility-sensitive corrected single-beam transmittance Ys and the unitary transmittance Ts ₄₆₀ of ₄₆₀ nm is 1.2% or less,

The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₅₅₀ of ₅₅₀ nm is within 1%

The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₆₁₀ of ₆₁₀ nm is within 1%

The visibility-corrected orthogonal transmittance of the two substrates is measured to be orthogonal to the absorption axis direction of not more than 0.01%

Wherein an average value of the orthogonal transmittances Tc Ave 430 to 480 of 430 nm to 480 nm when the two substrates are measured perpendicular to the absorption axis direction is 0.03% or less;

(2) the visual sensitivity-corrected parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%

A transmittance TP ₂₅₅ of ₂₅₅ nm in the case of measuring the parallel transmittance Yp of the substrate parallel to the absorption axis direction of the two substrates is expressed by the following formula (2)

0.75 X Yp - 13? Tp ₂₅₅ ? 0.75 X Yp + 1.0 (2)

The polarizing element described in (1) above.

(3) the visual sensitivity-corrected parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%

The transmittance Tc ₂₅₅ of ₂₅₅ nm in the case of measuring the parallel transmittance Yp and the two substrates perpendicularly to the absorption axis direction is represented by the following formula (3):

2.OX 10 ^-6 X Yp ^{4 .1} ? Tc ₂₅₅ ≤ 2.0 X 10 ^-6 X Yp ^{4 . 4} (3)

The polarizing element described in (1) or (2) above.

(4) The visibility-corrected parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%

(1) to (3), wherein the difference between the parallel transmittance Yp and the parallel transmittance Tp ₄₆₀ of ₄₆₀ nm measured when the two substrates are measured parallel to the absorption axis direction is within 3% A polarizing element described in any one of claims 1 to 5;

(5) The visibility-corrected transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%

The transmittance Tp ₂₉₅ of 295 nm when measured with the parallel transmittance Yp and the two substrates parallel to the absorption axis direction satisfies the following formula (4)

The transmittance Tp ₃₆₀ of 360 nm when measured with the parallel transmittance Yp and the two substrates parallel to the absorption axis direction The polarizing element according to any one of the above (1) to (4), which satisfies the following formula (5):

1.05 X Yp - 26? Tp ₂₉₅ ? 1.05 X Yp - 13 Equation (4)

1.25 X Yp - 26.25? Tp ₃₆₀ ≤ 1.25 X Yp - 16.25 (5)

(6) The transmittance Tc ₂₉₅ of 295 nm when the two substrates are measured perpendicular to the absorption axis direction satisfies the formula (6), and

(1) to (5), wherein the transmittance Tc ₃₆₀ of 360 nm in the case where the two substrates are measured parallel to the absorption axis direction satisfies the formula (7) device;

2.OX 10 ^-30 x Yp ^{18 . 6} ? Tc ₂₉₅ ≤ 2.OX 10 ^-30 X Yp ^{19 . 4} (6)

4.OX 10 ^-37 X Yp ^{22 .12} ? Tc ₃₆₀ ? 4.OX 10 ^-37 X Yp ^{22 . 67} (7)

(7) the transmittance Tc ₄₆₀ of ₄₆₀ nm when the two substrates are measured perpendicular to the absorption axis direction is 0.035% or less, and

The polarizing element according to any one of (1) to (6) above, characterized in that the transmittance Tc ₆₁₀ of ₆₁₀ nm is 0.01% or less when the two substrates are measured perpendicular to the absorption axis direction.

(8) The polarizing element according to any one of (1) to (7) above, wherein the substrate comprises a polyvinyl alcohol-based resin film and the degree of polymerization of the polyvinyl alcohol- ;

(9) A polarizing plate comprising a polarizing element according to any one of (1) to (8), wherein at least one surface of the polarizing element is provided with a support film;

(10) A liquid crystal display device comprising the polarizing element according to any one of (1) to (8) or the polarizing plate according to (9) above;

(11) A process for producing a polarizing element comprising a substrate having a polarizing function containing a hydrophilic polymer drawn by adsorbing boric acid and containing iodine,

(i) a step of adding a dichroic dye to a polyvinyl alcohol-based resin film to obtain a film containing a dichroic dye,

(ii) a step of stretching a film containing the dichroic dye to obtain a stretched film,

(iii) providing the stretched film to a post-treatment using a solution containing chloride or an iodide,

(iv) after the post-treatment, drying the film to obtain the substrate,

The concentration of the chloride-containing solution or iodide-containing solution is 0.1 to 15% by weight,

The following formula (1)

...식(1)

... (1)

By weight of the organic compound of the present invention.

The present invention relates to a polarizing element and a polarizing plate having a constant transmittance at each wavelength and having a high contrast, and the polarizing element and the polarizing plate are excellent in transmittance, high contrast ratio, and high color reproducibility, It can be used particularly as a polarizing plate for a liquid crystal display. The display using this display is highly reliable, has a high contrast for a long term, and has a display with high color reproducibility.

Carrying out the invention  Means for

≪ Polarizing element &

As a method for producing the polarizing element of the present invention, for example, there are a method of swelling a hydrophilic polymer film, a dyeing step of containing a dichroic dye, and then a waterproofing treatment, if necessary, followed by a stretching step, , And finally, a drying process is performed.

Examples of the hydrophilic polymer film used for the polarizing element include films containing a polyvinyl alcohol-based resin, an amylose-based resin, a starch-based resin, a cellulose-based resin or a polyacrylate-based resin, Is used as a film. Among them, a polyvinyl alcohol resin (hereinafter may be abbreviated as " PVA ") film is preferable. In the present invention, a polyvinyl alcohol based resin film containing a polyvinyl alcohol resin and a polarizing element including a dichroic substance such as iodine are most preferable. The thickness of these polarizing elements is not particularly limited, but is generally about 5 to 80 mu m.

The production method of the polyvinyl alcohol-based resin is not particularly limited and can be produced by a known method. For example, the polyvinyl alcohol-based resin can be obtained by saponifying a polyvinyl acetate-based resin. Here, examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers and unsaturated sulfonic acids. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol-based resin is preferably 1,000 to 10,000, more preferably 1,500 to 6,000. A film obtained by forming a polyvinyl alcohol-based resin can be used as a polyvinyl alcohol-based resin film.

In order to improve the optical properties of the present invention, the polymerization degree of PVA is required to be 1000 to 10000, and more preferably 3000 or more. When the degree of polymerization of PVA is less than 2000, it becomes difficult to exhibit high polarization performance. When the degree of polymerization is more than 7000, PVA hardens, film formability and stretchability are lowered and productivity is lowered. Therefore, from an industrial viewpoint, it is preferable that the PVA is 10000 or less.

The degree of polymerization of PVA means the degree of polymerization (viscosity average degree of polymerization) measured as follows.

0.28 g of PVA is dissolved in 70 g of distilled water at 95 캜 to prepare an aqueous 0.4% PVA solution and cooled to 30 캜. And cooled in a constant temperature water bath at 30 DEG C to obtain a sample for measuring the degree of polymerization. Subsequently, 10 mL of the sample for measuring the degree of polymerization is dried in a drier at 105 DEG C for 20 hours in an evaporation dish, and the weight [[alpha] (g)] of the sample for measuring the degree of polymerization is measured after drying. The concentration C (g / L) of the sample for measuring the degree of polymerization is calculated by the following equation (i).

C = 1000 x? / 10 (i)

Further, a sample for measurement of degree of polymerization or distilled water was put into an Ostwald viscometer with a 10 mL hole pipette and stabilized in a constant temperature water bath at 30 DEG C for 15 minutes. The viscosity-average degree of polymerization E is calculated from the following equations (ii) to (iv) by measuring the falling seconds t ₁ (seconds) and the falling seconds t ₀ (seconds) of the dropped polymerization degree measuring sample.

The saponification degree of PVA is preferably 99 mol% or more, more preferably 99.5 mol% or more. If the degree of saponification is less than 99 mol%, PVA tends to be eluted, resulting in in-plane staining of optical properties, deterioration of dyeability in the dyeing step, and cutting in the stretching step, I do not.

The PVA used in the present invention can be produced by saponifying a polyvinyl ester polymer obtained by polymerizing a vinyl ester. Examples of the vinyl esters include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate and vinyl benzoate. Or more. Among these, vinyl acetate is preferably used. There is no particular limitation on the polymerization temperature, but when methanol is used as the polymerization solvent, it is preferably around 60 占 폚 in that the boiling point of methanol is around 60 占 폚. PVA is not limited to a saponified vinyl ester homopolymer unless the effect of the present invention is impaired. For example, modified PVA vinyl ester obtained by graft-copolymerizing PVA with an unsaturated carboxylic acid or a derivative thereof, an unsaturated sulfonic acid or a derivative thereof, an? -Olefin having 2 to 30 carbon atoms in a proportion of less than 5 mol%, and an unsaturated carboxylic acid or derivative thereof , An unsaturated sulfonic acid or a derivative thereof, an α-olefin having 2 to 30 carbon atoms in a proportion of less than 15 mol%, and a halogenated aldehyde such as formaldehyde, butylaldehyde or benzaldehyde. A polyvinyl acetal-based polymer in which a part thereof is crosslinked, or the like.

The PVA obtained as described above is then formed into a film master. Examples of the PVA film-forming method include a method of melt-extruding a functional PVA, a softening film method, a wet film-forming method (discharging into a poor solvent), a gel film forming method (once a cooling gel is formed on a PVA aqueous solution and then a solvent is extracted and removed) A method (flowing a PVA aqueous solution on a substrate and drying), and a method using a combination thereof, but the present invention is not limited to these methods.

Examples of the solvent used in the film formation include dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethyl Propane, ethylene diamine, diethylene triamine, water, and the like, but are not limited thereto. The solvent may be one kind or a mixture of two or more kinds. The amount of the solvent used in the film formation is, for example, 50 to 95 mass% and preferably 70 to 95 mass%, but is not limited to these ranges. However, if the amount of the solvent is less than 50% by mass, the viscosity of the stock solution tends to be high, which makes it difficult to perform filtration and de-foaming at the time of production, and it becomes difficult to obtain a raw film without foreign matters and without defects. On the other hand, if the volatile fraction exceeds 95% by mass, the viscosity of the undiluted film-forming solution becomes too low to control the intended thickness, and the productivity is deteriorated due to the influence of the fluctuation of the surface due to wind during drying or the drying time .

In producing the master disc, a plasticizer may be used. Examples of the plasticizer include glycerin, diglycerin, ethylene glycol and the like, but are not limited thereto. The amount of the plasticizer to be used is not particularly limited, but is usually in the range of 5 to 15 parts by mass, based on 100 parts by mass of the PVA.

Examples of the drying method of the film master after the film formation include drying by hot air, contact drying using hot roll, drying with an infrared heater, and the like. One of these methods may be used singly or two or more of them may be combined and dried. The drying temperature is not particularly limited, but is preferably in the range of 50 to 70 占 폚.

The dried original film is preferably subjected to heat treatment in order to control its swelling degree to a predetermined range to be described later. Examples of the heat treatment method of the film master after film formation include a method using hot air or a method of bringing a film master into contact with hot roll, and there is no particular limitation as long as it is a method capable of heat treatment. One of these methods may be used alone, or two or more types may be used in combination. The heat treatment temperature and time are not particularly limited, but it is preferably in the range of 110 to 140 占 폚, and the treatment of 1 to 10 minutes is generally suitable, but is not particularly limited.

The thickness of the original film thus obtained is preferably 20 to 100 占 퐉, more preferably 20 to 80 占 퐉, and still more preferably 20 to 60 占 퐉. If the thickness is less than 20 占 퐉, the film tends to be easily broken. If the thickness exceeds 100 탆, the stress applied to the film at the time of stretching becomes large, the mechanical load in the stretching step becomes large, and a large-scale apparatus for enduring the load is required.

The swelling degree F of the master disc is preferably 180 to 250%, more preferably 205 to 235%, and even more preferably 210 to 230%. If the swelling degree F is less than 180%, the elongation at the time of stretching is small and the possibility of breaking at a low magnification increases, and it becomes difficult to perform sufficient stretching. When the degree of swelling F exceeds 240%, the swelling becomes excessively large, which causes wrinkles or sagging, which causes cutting at the time of stretching. In order to control the swelling degree F, for example, the degree of swelling F suitable for the temperature and time at the time of heat-treating the original film after film formation can be used.

The method for measuring the swelling degree F of the original disc is as follows.

The master disc is cut into 5 cm × 5 cm and immersed in 1 liter of distilled water at 30 ° C. for 4 hours. The immersed film is taken out from the distilled water, and after the water droplets on the surface are absorbed by wrapping with two pieces of filter paper, the weight [? (G)] of the film immersed in water is measured. Further, the film immersed and absorbed water droplets was dried in a drier at 105 DEG C for 20 hours, cooled in a desiccator for 30 minutes, and then the weight [gamma (g)] of the dried film was measured, Thereby calculating the swelling degree F of the original film.

Swelling degree F = 100 x? /? (%) (V)

The polarizing element of the present invention is produced by a method including the steps described below using the original film produced as described above.

(Swelling process)

The above-mentioned film master is firstly provided in a swelling process for swelling the film.

In this process, the swelling is achieved by immersing the polyvinyl alcohol-based resin film in a solution at 20 to 50 캜 for 15 seconds to 10 minutes. The solution at this time is preferably water, but may be a water-soluble organic solvent such as glycerin, ethanol, ethylene glycol, propylene glycol or low molecular weight polyethylene glycol, or a mixed solution of water and a water-soluble organic solvent. In order to prevent the occurrence of wrinkles or folding (folding) in the swelling step, it is preferable that the stretching is appropriately performed. The stretching ratio is preferably 1.00 to 1.50 times, more preferably 1.10 to 1.35 times. In the case of shortening the time for producing the polarizing element, this step may be omitted because a swelling effect is obtained in the dyeing step of the dye upon iodine and iodide treatment.

(Dyeing process)

Subsequently, the swollen polyvinyl alcohol-based resin film is supplied to a dyeing step of dyeing in a solution containing a dichroic dye.

As the solvent of the solution, water is preferable, but it is not particularly limited. Examples of the dichroic dye include many iodine ions obtained from a mixed solution of iodine and iodide, and dichroic dyes of organic compounds. As the iodide, for example, potassium iodide, ammonium iodide, cobalt iodide, zinc iodide and the like can be used, but it is not limited to the iodide shown here. The iodine concentration in the mixed solution of iodine and iodide is 0.0001 to 0.5 wt%, preferably 0.001 to 0.4 wt%. The concentration of iodide used is preferably 0.0001 to 8 wt%. In some cases, in order to correct the color, as the dichroic dye of the organic compound, for example, a dichroic dye described in Non-Patent Document 1 may be used to perform color correction within a range that does not impair the performance of the present invention good. The dye is not limited, and a known dichroic dye can be used. The dye concentration is not particularly limited, but is preferably about 0.006 wt% to 0.3 wt%, for example. When the dyeability is insufficient, it is preferable to perform dyeing by adding a coloring aid such as sodium tripolyphosphate and / or manganese (sodium sulfate). The dyeing temperature is 5 to 50 캜, preferably 5 to 40 캜, and more preferably 10 to 30 캜. The dyeing time can be suitably adjusted in accordance with the transmittance and the like of the polarizing element to be obtained, but is about 30 seconds to 6 minutes, more preferably 1 minute to 5 minutes. Also in this step, it is preferable to appropriately stretch to prevent the occurrence of wrinkles or folding (folding). The draw ratio is preferably 0.90 to 2.00 times, more preferably 1.00 to 1.30 times.

In the dyeing step, a crosslinking agent and / or a water-proofing agent may be added to the solution containing the dichroic dye. Examples of the crosslinking agent include boron compounds such as boric acid, borax or ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyvalent isocyanate compounds such as biuret type, isocyanurate type or block type, Titanium compounds, and the like. In addition, ethylene glycol glycidyl ether, polyamide epichlorohydrin, and the like can be used. Examples of the water-proofing agent include peroxydisuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, magnesium chloride and the like. good. The concentration to be added is, for example, 0.1 to 5.0 wt%, preferably 2 wt% to 4 wt% with respect to the solution containing the dichroic dye when boric acid is added. If necessary, the polyvinyl alcohol resin film containing the dichroic dye may be washed after the dyeing step and before the next stretching step. As the solvent for washing, water is generally used, but an alcohol solvent, a glycol solvent, glycerin or a mixed solvent thereof may be used, and the solvent is not particularly limited. The temperature and time for washing may be suitably adjusted in accordance with the transmittance of the intended polarizing element and the type of the dichroic dye to be used.

(Water resistance treatment step)

Subsequently, after the dyeing step, the dyed film is supplied to a waterproofing treatment step in which waterproofing treatment is carried out if necessary.

In the above process, the film is treated with a solution containing a crosslinking agent and / or a water-proofing agent. Examples of the crosslinking agent and / or the water-proofing agent include boron compounds such as boric acid, borax and ammonium borate, polyvalent aldehydes such as glyoxal or glutaraldehyde, polyvalent isocyanate compounds such as biuret type, isocyanurate type or block type, Based compounds such as ethyleneglycol diglycidyl ether, ethyleneglycol diglycidyl ether, glycerin diglycidyl ether, glycerin diglycidyl ether, glycerin diglycidyl ether, glycerin diglycidyl ether, glycerin diglycidyl ether, Ether, ammonium chloride, magnesium chloride and the like, but boric acid is preferred. As the solvent at this time, for example, water, an alcohol solvent, a glycol solvent, glycerin or a mixed solvent thereof may be used. The concentration of the crosslinking agent and / or the water resistance agent is preferably about 0.1 wt% to about 6.0 wt%, more preferably about 2 wt% to about 4 wt%, in the solution, for example, in the case of an aqueous solution of boric acid. The treatment temperature in this step is about 5 to 60 占 폚, preferably about 5 to 45 占 폚. The treatment time is preferably about 1 minute to 5 minutes. Also in this step, it is preferable to appropriately stretch to prevent the occurrence of wrinkles or folding (folding), and the stretching magnification thereof is about 0.95 to 1.5 times.

(Drawing step)

Then, the polyvinyl alcohol-based resin film is provided in a stretching step of stretching.

In this process, the film is uniaxially stretched. As the drawing method, any of a wet drawing method and a dry drawing method may be used.

Specific examples of the dry stretching method include, but are not limited to, a roll-to-bed stretching method, a roll heating stretching method, a rolling stretching method, and an infrared heating stretching method. The temperature at the time of stretching is preferably from room temperature to 180 ° C and the humidity is about 20 to 95% RH. The stretching may be performed in a single stage or may be multi-stage stretching in two or more stages.

The wet stretching method is a method in which stretching is carried out in water, a water-soluble organic solvent, or a mixed aqueous solution thereof. Preferably, a boron compound such as boric acid, borax, or ammonium borate is added to the water, the water-soluble organic solvent, Polyvalent isocyanate-based compounds such as biuret type, isocyanurate type and block type, titanium-based compounds such as titanium oxysulfate, ethylene glycol glycidyl ether, polyamide epichlorohydrate, In a solution containing a cross-linking agent such as phosphorus pentachloride, ammonium persulfate, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride or magnesium chloride, and / It is preferable to carry out the stretching treatment while immersing it, and it is preferable that the stretching is carried out in an aqueous solution of boric acid Is recommended. The concentration of the crosslinking agent and / or the water-proofing agent is preferably 0.5 to 8 0.5 to 8 wt%, more preferably 2.0 to 4.0 wt%. The draw ratio is preferably 3 to 8 times, more preferably 5 to 7 times. The stretching temperature is preferably 40 to 60 占 폚, more preferably 45 to 55 占 폚. The stretching time is preferably 30 seconds to 20 minutes, more preferably 2 minutes to 5 minutes. The stretching treatment may be a single stage or a multi-stage stretching of two or more stages.

The surface of the stretched dichroic dye-containing polyvinyl alcohol-based resin film may be washed since foreign matters may precipitate or foreign matter may adhere thereto. As the solvent to be cleaned, water, an alcohol-based solvent and the like can be used, but the present invention is not limited thereto. The cleaning solvent may contain a crosslinking agent such as boric acid and / or a water-proofing agent for the purpose of improving durability of the film. The concentration of the crosslinking agent and / or the water resistance agent is not limited, but is, for example, 0.1 to 10 wt%.

(Post-treatment process)

Then, in order to adjust the color, improve the polarization characteristics, and improve the durability, a post-treatment step of post-treating the film is performed.

Specifically, in the above step, a dichroic dye is contained, and the uniaxially stretched polyvinyl alcohol resin film is treated with a solution containing chloride or iodide. Examples of the chloride or iodide include iodides such as potassium iodide, sodium iodide, ammonium iodide, cobalt iodide and zinc iodide, and chlorides such as zinc chloride, potassium chloride and sodium chloride, and one or more of them The solution is mixed and processed. The concentration of chloride or iodide in the solution is preferably 0.1 to 15 wt%, more preferably 0.15 to 10 wt%. Also in this step, it is preferable to appropriately stretch to prevent occurrence of wrinkles and folding (folding), and the stretching magnification at that time is preferably 0.90 to 1.10 times. The treatment temperature is preferably 5 to 50 占 폚 or less, more preferably 20 to 40 占 폚. The treatment time is, for example, about 1 second to 5 minutes, preferably 5 seconds to 30 seconds. In this step, the crosslinking agent and / or the water resistance agent may be added. The concentration to be added is, for example, 0.5% to 10% by weight.

Examples of the solvent to be used in the treatment process so far include water, dimethylsulfoxide, N-methylpyrrolidone, methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene But are not limited to, alcohols such as glycol, tetraethylene glycol or trimethylolpropane, and amines such as ethylenediamine or diethylenetriamine. Mixtures of one or more of these solvents may also be used. The most preferred solvent is water.

(Drying step)

After the post-treatment step, the substrate of the polarizing element of the present invention is obtained by passing through a drying step.

Examples of the drying method include natural drying, compression by a roll, air knife, a method of removing water on the surface by an absorbing roll, and drying by heating. The drying temperature in the case of heat drying is preferably 20 to 90 占 폚, more preferably 40 to 70 占 폚. The drying time is preferably about 30 seconds to 20 minutes, more preferably about 2 minutes to 10 minutes. In this drying step, the polyvinyl alcohol-based resin film is preferably stretched properly in order to prevent wrinkles and patterns from being generated due to shrinkage of the polyvinyl alcohol-based resin film upon drying. The stretching magnification at that time is preferably 0.95 to 1.10 times.

The substrate of the polarizing element is obtained by passing through the swelling process, the dyeing process, the optional water resistance treatment process, the stretching process, the post-treatment process, and the drying process. Thus, the substrate thus obtained is a substrate having a polarizing function containing a hydrophilic polymer drawn by adsorbing boric acid and containing iodine, and is a substrate in the form of free acid, an organic compound represented by the following formula (1) And the difference between the visual sensitivity-corrected single-use transmittance Ys and the simplex transmittance Ts ₄₆₀ of ₄₆₀ nm is within 1.2%, and the visual sensitivity-corrected single-substance transmittance Ys is 40% to 42.5% The difference between Ys and 550 nm of the simple transmittance Ts _{550 is} within 1%, and the difference between the visibility-sensitive corrected single transmittance Ys and the simple transmittance Ts ₆₁₀ of ₆₁₀ nm is within 1%, and the two substrates are measured orthogonally to the absorption axis direction And the visibility-sensitive correction quadrature transmittance Yc in one case is not more than 0.01%, and the two substrates are orthogonal to the absorption axis direction, and the orthogonal transmittance of 430 to 480 nm Has an average value is adjusted to 0.03% or less.

...(1)

...(One)

(1), R ₁ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and k, m and n each represent 0 or 1, provided that m + n> .

In order to obtain a polarizing element including a substrate having the above properties, it is necessary to contain the organic compound of the formula (1). Thus, as a method of containing the organic compound, a method of impregnating a base material with a solution containing an organic compound in any of steps of a dyeing step of containing a dichroic dye, an arbitrary water hydration treatment step, a stretching step and a post- However, it is also possible to use a method in which a process is provided and contained before the step of dyeing iodine and iodine compound after swelling the polyvinyl alcohol based resin film, a method in which the dyeing step including the dichroic dye is simultaneously added, A method in which a dye is dyed and then a dye is added to the dyed product before the dyeing step, or a method in which the dyed dye is simultaneously contained by a post-treatment step. Further, it is more preferable to provide a process before the step of dyeing the iodine and iodine compound after swelling the polyvinyl alcohol-based resin film.

Specific examples of the dye represented by the formula (1) include C.I. Direct Yellow 28, C.I. Direct YeIIow 29 can be exemplified. The concentration of the organic compound of the formula (1) is not particularly limited, but is suitably about 0.05 part by weight to 3 parts by weight with respect to 1000 parts by weight of water. When the dyeability is insufficient, sodium tripolyphosphate and And / or dye (sulphate) is added to the coloring agent to perform dyeing. The dyeing temperature is 5 to 50 占 폚, preferably 5 to 40 占 폚, and more preferably 10 to 30 占 폚. The dyeing time can be appropriately adjusted in accordance with the transmittance and the like of the polarizing element to be obtained. For example, the dyeing time is preferably about 30 seconds to 6 minutes, and is preferably 1 to 5 minutes.

Next, a more specific example of the dye represented by the formula (1) is shown in the following free acid form.

[Compound Example 1]

[Compound Example 2]

[Example 3]

It is also important to treat the uniaxially stretched polyvinyl alcohol-based resin film containing the dichroic dye in a post-treatment step with a solution containing a chloride or iodide having a suitable concentration. In this process, the concentration of the chloride or iodide in the solution in accordance with the stretching conditions, and the treatment time thereof, need to be adjusted. It is very important that the concentration and the treatment time are adjusted in accordance with the impregnation conditions of the iodide to the polarizing element, the iodide such as potassium iodide, and the chloride such as potassium chloride into the polarizing element. In particular, the concentration is also affected by the stretching state of the stretching process, the temperature and humidity at the place where the polarizing element is produced, and therefore, very fine fine adjustment is required. Typically, the concentration of the chloride-containing solution or the iodide-containing solution used in the post-treatment step is adjusted by adding 1.0 to 150 parts by weight, preferably 1.5 to 100 parts by weight, of chloride or iodide to 1000 parts by weight of water .

Further, it is preferable to treat the film while maintaining the stretched magnification and / or stretching tension so that shrinkage or expansion of the film can not occur as far as possible. In addition, it is preferable that the treatment is performed in a state in which there is no difference in relative speed between the transporting speed of the film and the water flow rate of the post-treatment process, and further, the treatment liquid is sufficiently treated to the inside of the polarizing element by using ultrasonic waves Is more preferable. By the above-described method, the post-treatment step is performed to obtain the polarizing element of the present invention.

An index to be manufactured and adjusted to have better performance as a polarizing element is the transmittance at 255 nm in the ultraviolet region. This is because the organic compound represented by the formula (1) has absorption at 255 nm, and therefore, when the compound is contained in the substrate, it can be discriminated whether or not it is a polarizing element having a good performance by 255 nm of the ultraviolet region . The absorption of the ultraviolet region of the iodine or iodine compound is an absorption at 220 nm, 295 nm, and 360 nm, and is different from the absorption of the organic compound of Formula (1), so that the content of the compound of Formula (1) can be suitably adjusted. The content of the compound of the formula (1) is preferably in the range of 33% to 37% in the case of measuring the two transmissive liquid crystal materials parallel to the absorption axis direction, It is preferable that the transmittance Yp and the transmittance Tp ₂₅₅ of ₂₅₅ nm in the case of measuring the two substrates parallel to the absorption axis direction satisfy the following formula (2). More preferably, formula (2B) is satisfied.

0.75 X Yp - 13? Tp ₂₅₅ ? 0.75 X Yp + 1.0 (2)

0.75 X Yp - 11? Tp ₂₅₅ ? 0.75 X Yp .... (2B)

As the index for determining the content of the compound of the formula (1), the visibility-corrected parallel transmittance Yp when measured with two substrates parallel to the absorption axis direction is 33% to 37 %, And the transmittance Tc ₂₅₅ of ₂₅₅ nm in the case of measuring the parallel transmittance Yp and the two substrates perpendicularly to the absorption axis direction satisfies the following formula (3).

2.0 X 10 ^{- 6} X Yp ^{4 .1} ? Tc ₂₅₅ ? 2.0 X 10 ^{- 6} X Yp ^{4 . 4} (3)

It is also necessary to adjust not only the content of the organic compound represented by the formula (1) but also the content of the iodine and the iodine compound. Concretely, the visibility-corrected parallel transmittance Yp in the case of measuring two substrates parallel to the absorption axis direction is in the range of 33% to 37%, and the transmittance Yp and the transmittance Yp of the two substrates are parallel to the absorption axis direction The difference between the transmittance Tp ₄₆₀ of 460 nm and the transmittance Tp ₄₆₀ of 460 nm is required to be controlled within 3%. In order to make the difference between Yp and Tp ₄₆₀ within 3%, the transmittance Tp ₂₉₅ of 295 nm when measured with two substrates parallel to the absorption axis direction And a transmittance Tp _{360 of 360} nm . The transmittance Tp _{295 of 295} nm And the transmittance Tp ₃₆₀ of ₃₆₀ nm are said to vary due to the content of poly-iodine such as I ₃ - and I ₅ - in the polarizing element. The transmittance of 295 nm and 360 nm can be adjusted by adjusting the content of poly-iodine such as I ₃ - and I ₅ - in the polarizing element, and Yp and Yp ₄₆₀ Can be adjusted within 3%.

In order to manufacture a better polarizing element, the visibility-corrected transmittance Yp obtained by measuring two substrates parallel to the absorption axis direction is in the range of 33% to 37%, and the transmittance Yp and the two substrates The transmittance Tp ₂₉₅ of 295 nm when measured in parallel with the absorption axis direction satisfies the following formula (4) and the Yp and the two substrates are measured parallel to the absorption axis direction: 360 nm It is necessary to adjust so that the transmittance Tp ₃₆₀ of the light guide plate satisfies the following formula (5).

1.05 X Yp - 26? Tp ₂₉₅ ≪ / = 1.05 X Yp - 13 (4)

1.25 X Yp - 26.25? Tp ₃₆₀ ? 1.25 X Yp - 16.25 (5)

In order to improve the performance of the polarizing element, in particular, in order to improve the performance of 380 nm to 480 nm, which is the visible range of the polarizing element, it is necessary to improve the orientation of poly iodides such as I ₃ - and I ₅ - at 295 nm and 360 nm , The transmittance Tc ₂₉₅ of 295 nm in the case of satisfying the above formulas (4) and (5) and measuring the two substrates perpendicularly to the absorption axis direction satisfies the following formula (6) It is further preferable that the transmittance Tc ₃₆₀ of 360 nm in the case of measuring two sheets parallel to the absorption axis direction satisfies the following formula (7). Of the following ^{formula, Yp 18 .6, Yp 19 .4} , Yp and Yp respectively, of the ^{22 .12 22 .67} represents the power of parallel transmittance Yp.

2.O X10 ^{- 30} X Yp ^{18 . 6} ? Tc ₂₉₅ ? 2.0 X 10 ^-30 X Yp ^{19 . 4} (6)

4.OX 10 ^-37 X Yp ^{22 .12} ? Tc ₃₆₀ ? 4.OX 10 ^-37 X Yp ^{22 . 67} (7)

In recent years, the transmittance of 430 to 480 nm centered at 460 nm is important for improving the contrast of the polarizing element in that blue light of 460 nm is emitted as white light by using a fluorescent material as the LED backlight light source. In particular, when the transmittance of the polarizing element in the case of measuring two 460 nm substrates perpendicularly to the absorption axis direction is high, blue light is leaked, and black can not be expressed as a display. Also, at this time, if the transmittance at 610 nm has a certain transmittance or less as compared with 460 nm, the complete black can not be expressed similarly, and the contrast between white and black can not be realized. Therefore, the transmittance of the polarizing element is measured when the transmittance at 460 nm is 0.035% or less when measured with two substrates perpendicular to the absorption axis direction, and the two substrates are measured at right angles to the absorption axis direction It is preferable to adjust the transmittance at 610 nm to be 0.01% or less.

For this purpose, the present invention can be easily achieved by using a film master comprising a polyvinyl alcohol based resin film having a degree of polymerization of 1000 to 10000 as a base material of a polarizing element. More preferably, the degree of polymerization of the polyvinyl alcohol-based film is from 3500 to 6000, and more preferably from 4500 to 6000.

<Polarizer>

The polarizing plate of the present invention can be obtained by providing a transparent protective layer on at least one surface or both surfaces of the polarizing element of the present invention obtained through the above processes. Specifically, the transparent protective layer can be provided by applying or laminating a polymer or film forming the protective layer to the polarizing element of the present invention. As the transparent polymer or film forming the transparent protective layer, a transparent polymer or film having high mechanical strength and good thermal stability is preferable. Further, it is more preferable that the water barrier property is excellent. As the material used as the transparent protective layer, for example, a cellulose acetate resin or a film thereof such as triacetylcellulose or diacetylcellulose, an acrylic resin or a film thereof, a polyester resin or a film thereof, a polyallylate resin or a film thereof, a norbornene , Polyolefins having a cyclic structure or a norbornene skeleton or copolymers thereof, polymers having a main chain or side chain of imide and / or amide, such as polyethylene terephthalate, A resin or a polymer or a film thereof. Since it is known that the polyvinyl alcohol-based resin generally acts as an alignment film, a resin having liquid crystallinity or a film thereof can be obtained by applying, for example, a rubbing treatment or an orientation film coating and orientation treatment to the surface of the obtained polarizing element May be provided. The thickness of the protective film is, for example, about 0.5 to 200 mu m. When these films are provided on both surfaces of the polarizing element, the same film or different films may be used.

When the film as the transparent protective layer is laminated with the polarizing element of the present invention, it is preferable to use an adhesive. Examples of the adhesive include polyvinyl alcohol-based, urethane-based, acrylic-based, and epoxy-based adhesives. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Goseonol NH-26 (manufactured by Nihon Kogyo Co., Ltd.) and Xceval RS-2117 (manufactured by Kuraray Co., Ltd.). To the adhesive, a cross-linking agent and / or a water-proofing agent may be added. The adhesive may contain an inorganic acid or its salt and / or an organic acid in a concentration of 0.0001 wt% to 20 wt%, preferably 0.02 wt% to 5 wt%. As the polyvinyl alcohol-based adhesive, an adhesive obtained by mixing a maleic anhydride-isobutylene copolymer alone or in combination with a crosslinking agent can be used. Examples of the maleic anhydride-isobutylene copolymer include isobarane # 18 (manufactured by Kuraray Co., Ltd.), isoban # 04 (manufactured by Kuraray Co., Ltd.), ammonia modified isoban # 104 (Manufactured by Kuraray Co., Ltd.), imidized isoban # 304 (manufactured by Kuraray Co., Ltd.) and imidized isoban # 310 (manufactured by Kuraray Co., Ltd.). A water-soluble polyfunctional epoxy compound may be used as the crosslinking agent. Examples of the water-soluble polyvalent epoxy compound include Denacol E X-521 (manufactured by Nagase Chemtech Corp.) and Tetralat-C (manufactured by Mitsui Gas Chemical Co., Ltd.). As the additive for the adhesive, it is more preferable that the buffer, the inorganic acid or its salt and / or the organic acid, the zinc compound, the chloride or the iodide and the like are used as the buffer, inorganic acid or its salt and / To 10 wt%, the durability can be similarly improved. It is possible to bond the film, which is a transparent protective layer, to the polarizing element of the present invention by bonding with the adhesive, followed by heating and drying and heat treatment.

When the obtained polarizing plate is bonded to a display device such as a liquid crystal display, or used in a polarizing filter or a polarizing lens, various kinds of materials for improving the viewing angle and / or improving the contrast on the surface of the protective layer or film, A functional layer, a layer or film having brightness enhancement can be provided. In order to bond the polarizing plate to these films or display devices, it is preferable to use a pressure-sensitive adhesive.

The polarizing plate may have various known functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer on the other surface, that is, the exposed surface of the protective layer or the film. In order to produce the layer having various functionalities, it is preferable to provide the layer on the other side by a coating method, but the film having the function may be bonded through an adhesive or a pressure-sensitive adhesive. Further, the various functional layers may be layers or films for controlling the retardation.

By the above-described method, a polarizing element or a polarizing plate having a constant transmittance at each wavelength and high contrast can be obtained. The polarizing element or polarizing plate of the present invention thus obtained can maintain a stable performance for a long period of time because the polarizing element or the polarizing plate of the present invention has a high polarization performance, that is, a high contrast, .

<Liquid Crystal Display Device>

Further, the image display device of the present invention can be obtained by using the polarizing plate of the present invention for a liquid crystal display, an electroluminescence display device, a CRT, or the like. In particular, a liquid crystal display device can be obtained by bonding the polarizing plate of the present invention to both sides of a liquid crystal cell constituting a liquid crystal display together with a retardation film together with a pressure sensitive adhesive as necessary.

Example

Hereinafter, the present invention will be described in further detail with reference to examples, but the present invention is not limited thereto.

The transmittance shown in each example was evaluated as follows.

The transmittance of each wavelength when the two polarizing elements or the polarizing plates are superimposed so that their absorption axes are the same is referred to as a parallel transmittance Tp , And the transmittance of each wavelength when two polarizing plates are superimposed so that their absorption axes are orthogonal is referred to as an orthogonal transmissivity Tc.

Each of the spectral transmittances Ts, Tp and Tc was measured using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.).

The visibility-sensitivity corrected single-beam transmittance Ys was calculated from the following formula (8) from the single-wavelength transmittance Ts measured for each predetermined wavelength interval d? (Here, 5 nm) in a wavelength range of 400 to 700 nm. In the formula, P? Represents the spectral distribution of the standard light (C light source), and y? Represents the color matching function based on JIS Z 8729 (C light source 2 ° field of view).

식(8)

Equation (8)

The visual sensitivity-corrected parallel transmittance Yp was calculated from the parallel transmittance Tp measured at intervals of a predetermined wavelength interval d? (Here, 5 nm) in a wavelength range of 400 to 700 nm by the following equation (9). In the formula, P? Represents the spectral distribution of the standard light (C light source), and y? Represents the color matching function based on JIS Z 8729 (C light source 2 ° field of view).

식(9)

Equation (9)

The visibility-corrected orthogonal transmittance Yc was calculated from the orthogonal transmittance Tc measured at intervals of a predetermined wavelength interval d? (Here, 5 nm) in a wavelength range of 400 to 700 nm by the following formula (10). In the formula, P? Represents the spectral distribution of the standard light (C light source), and y? Represents the color matching function based on JIS Z 8729 (C light source 2 ° field of view).

식(10)

Equation (10)

The degree of polarization Py was obtained from the following equation (11) from the visibility-correcting equilibrium transmittance Yp and the visibility-corrected orthogonal transmittance Yc.

식(11)

Equation (11)

Example 1

(VF-PM manufactured by Kuraray Co., Ltd.) having a thickness of 60 占 퐉, a degree of polymerization of 5,500 and a degree of saponification of 99% or more was swollen in warm water at 40 占 폚 and then 1,000 parts by weight of water, WO 2005/015275 , 0.02 part by weight of a dye having the structure of formula (1) described in 1, and 1.0 part by weight of sodium tripolyphosphate was treated for 1 minute and 30 seconds, then 1000 parts by weight of water, 28.6 parts by weight of boric acid (manufactured by Societa larderello spa) , 0.14 parts by weight of iodine (manufactured by Junsei Chemical Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing. The dyed film was stretched 5 times at 58 ° C with a solution containing 3% by weight of boric acid, and after stretching, 3.5 parts by weight of potassium iodide was added to 1000 parts by weight of water to prepare an iodide-containing aqueous solution. While the stretching magnification is maintained and the ultrasonic wave of 20 kHz to 40 kHz is applied while the difference between the conveying speed at which the film is processed and the relative speed between the flow rate of the water stream in the processing step is almost constant, Lt; / RTI &gt; The film in which the potassium iodide aqueous solution was immersed for 20 seconds was then dried for 10 minutes by a dryer at 70 DEG C to obtain the polarizing element of the present invention.

Example 2

(VF-PM manufactured by Kuraray Co., Ltd.) having a thickness of 60 占 퐉, a degree of polymerization of 4000 and a degree of saponification of 99% or more was laminated on a polyvinyl alcohol film having a thickness of 40 占 퐉, a degree of polymerization of 4000 and a degree of saponification of 99% VF-PH) was used as the polarizing element of Example 1. q A polarizing element of the present invention was obtained.

Example 3

A polarizing element was obtained in the same manner as in Example 2 except that the time for the dyeing treatment was changed to 1 minute and 30 seconds.

Example 4

A polarizing element was obtained in the same manner as in Example 1 except that the time for the dyeing treatment was changed to 1 minute and 30 seconds.

Example 5

(VF-PM manufactured by Kuraray Co., Ltd.) having a thickness of 60 占 퐉, a degree of polymerization of 5,500 and a degree of saponification of 99% or more was swollen in warm water at 40 占 폚 and then 1,000 parts by weight of water, WO 2005/015275 0.02 parts by weight of a coloring matter having the structure of formula (1) described in 1, and 1.0 part by weight of sodium tripolyphosphate was treated for 1 minute and 30 seconds, followed by 1000 parts by weight of water, 28.6 parts by weight of boric acid (manufactured by Societa larderello spa) , 0.14 parts by weight of iodine (manufactured by Junsei Kagaku Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing. The dyed film was stretched 5 times at 58 占 폚 with a solution containing 3% by weight of boric acid. After stretching, stretching magnification was maintained while maintaining the stretching magnification. Thus, the conveying speed at which the film was processed, Was immersed in a state in which the difference in speed between the speed and the relative speed was almost constant, and the post-treatment process was performed for 20 seconds. Thereafter, it was dried for 10 minutes by a dryer at 70 캜 to obtain a polarizing element.

Comparative Example 1

1000 parts by weight of water, 1000 parts by weight of water, 1 part by weight of boric acid (manufactured by Societa larderello spa), 1 part by weight of water, , 0.14 parts by weight of iodine (manufactured by Junsei Chemical Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing treatment. Except that the aqueous solution prepared by adding 35 parts by weight of potassium iodide to the parts by weight was stirred at a speed of 60 rpm and the post-treatment step was performed for 20 seconds while maintaining the magnification after stretching. Device was obtained.

Comparative Example 2

1000 parts by weight of water, 1000 parts by weight of water, and 10 parts by weight of boric acid (manufactured by Societa larderello spa) without treatment with an aqueous solution containing a dye having the structure of formula (1) described in Synthesis Example 1, International Publication No. W02005 / , 0.14 parts by weight of iodine (manufactured by Junsei Chemical Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing treatment. Except that the aqueous solution prepared by adding 35 parts by weight of potassium iodide to the parts by weight was stirred at a rate of 60 rpm and the post-treatment step was conducted for 20 seconds while maintaining the magnification after stretching, Device was obtained.

Comparative Example 3

1000 parts by weight of water, 1000 parts by weight of water, and 10 parts by weight of boric acid (manufactured by Societa larderello spa) without treatment with an aqueous solution containing a dye having the structure of formula (1) described in Synthesis Example 1, International Publication No. W02005 / , 0.14 parts by weight of iodine (manufactured by Junsei Chemical Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing treatment. Except that the aqueous solution prepared by adding 50 parts by weight of potassium iodide to parts by weight of the solution was stirred at a rate of 60 rpm and the post-treatment step was conducted for 20 seconds while maintaining the magnification after stretching, Device was obtained.

Comparative Example 4

1000 parts by weight of water, 1000 parts by weight of water, and 10 parts by weight of boric acid (manufactured by Societa larderello spa) without treatment with an aqueous solution containing a dye having the structure of formula (1) described in Synthesis Example 1, International Publication No. W02005 / , 0.14 parts by weight of iodine (manufactured by Junsei Chemical Co., Ltd.) and 10.27 parts by weight of potassium iodide (manufactured by Junsei Chemical Co., Ltd.) for 2 minutes at 30 ° C for dyeing treatment. Except that the aqueous solution prepared by adding 50 parts by weight of potassium iodide to 50 parts by weight of water was stirred at a rate of 60 rpm and the post-treatment step was conducted for 20 seconds while maintaining the magnification after stretching, Device was obtained.

Comparative Example 5

The iodine-based polarizing plate SKN-18242P manufactured by Polar Techno Inc. was immersed in dichloromethane, and the polarizing element was extracted to obtain a comparative sample.

Comparative Example 6

1000 parts by weight of water, 1000 parts by weight of water, and 10 parts by weight of boric acid (manufactured by Societa larderello spa) without treatment with an aqueous solution containing a dye having the structure of formula (1) described in Synthesis Example 1, International Publication No. W02005 / 28.6 parts by weight, iodine (manufactured by Junsei Chemical Co., Ltd.), 0.25 parts by weight, and potassium iodide (manufactured by Junsei Chemical Co., Ltd.), 17.7 parts by weight, were immersed in an aqueous solution at 30 DEG C for 2 minutes, A polarizing element was obtained in the same manner as in Example 5 except that the substrate was immersed in water and treated for 20 seconds.

Comparative Example 7

1000 parts by weight of water, 0.1 part by weight of a coloring matter having the structure of formula (1) described in Synthesis Example 1, and 1.0 part by weight of sodium tripolyphosphate was treated for 3 minutes, In the same manner as in Example 1, a polarizing element was produced. The resultant polarizing plate was apparently colored yellow.

Table 1 shows the parameters of the polarizing element obtained in Examples 1 to 5 and Comparative Examples 1 to 7. The parameters shown in Table 1 are as follows.

Sensitivity corrected Single Transmittance Ys,

The visibility-corrected parallel transmittance Yp,

Sensitivity Correction Transmittance Ye,

A single transmittance Ts _{460 of 460 nm} ,

A parallel transmittance Tp ₄₆₀ of 460 nm in the case of measuring two substrates in parallel with the absorption axis direction,

The orthogonal transmittance Tc ₄₆₀ of 460 nm when measured by making two substrates perpendicular to the absorption axis direction,

A single transmittance Ts _{550 of 550} nm,

A unitary transmittance Ts _{610 of 610} nm,

The orthogonal transmittance Tc _{610 of 610} nm when measured by making two substrates perpendicular to the absorption axis direction,

An average value Ts Ave 430 to 480 of a simple transmittance of 430 nm to 480 nm,

An average value Tp Ave 430-480 of the transmittance of the smear of 430 nm to 480 nm when the two substrates are measured parallel to the absorption axis direction,

The average value of the transmittance on the orthogonal axis of 430 to 480 nm when measured by making two substrates perpendicular to the absorption axis direction Tc Ave 430 to 480.

Table 2 shows other parameters obtained for Examples 1 to 5 and Comparative Examples 1 to 7. The parameters shown in Table 2 are as follows.

A parallel transmittance Tp _{255 of 255} nm obtained by measuring two substrates in parallel with the absorption axis direction,

Two orthogonal transmittances Tc _{255 of 255} nm obtained by measuring two substrates perpendicularly to the absorption axis direction,

A parallel transmittance Tp _{295 of 295} nm obtained by measuring two substrates in parallel with the absorption axis direction,

Two orthogonal transmittances Tc _{295 of 295} nm obtained by measuring two substrates perpendicularly to the absorption axis direction,

A parallel transmittance Tp _{360 of 360} nm obtained by measuring two substrates in parallel with the absorption axis direction,

Cross transmissivity of which it can be obtained by measurement to be perpendicular to the substrate sheet 2 to the absorption axis direction 360nm Tc _360.

As is clear from the above results, the polarizing elements of Examples 1 to 5 are polarizing elements having a substantially constant transmittance at each wavelength, and the visibility-correcting single transmittance Ys measured in a single measurement is 40.0% to 42.5% The unitary transmittance Ys and the unitary transmittance Ts _{460 of 460 nm} Is 1.2% or less, the visual sensitivity-corrected single-unit transmittance Ys and the single-unit transmittance Ts _{550 of 550} nm , And the difference between the visibility-sensitive corrected single-beam transmittance Ys and the _610- nm single-wavelength transmittance Ts _{610 is} within 1%, and the two substrates are measured orthogonally to the absorption axis direction, It is known that the average value of the orthogonal transmittances Tc Ave 430 to 480 of 430 to 480 nm obtained by measuring Yc in a range of not more than 0.01% and making the two substrates perpendicular to the absorption axis direction is 0.03% or less.

When the polarizing elements of Examples 1 to 5 are provided in parallel to the absorption axis, the transmittance of 430 nm to 480 nm is preferably in the range of 500 nm to 650 nm And the uniformity of light emission at each wavelength could be preserved. Further, even when the visual sensitivity correcting quadrature transmittance Yc is 0.01% or less and the average value of the orthogonal transmittances Tc Ave 430 to 480 of 430 to 480 nm is 0.03% or less, these polarizing elements have high contrast, Which is a polarizing element or a polarizing plate which can be made constant.

Therefore, the polarizing elements of Examples 1 to 5 obtained by the above-mentioned methods, or the polarizing plate produced by using these polarizing elements, exhibited a high transmittance, a high contrast ratio, and a very high color reproducibility, in particular as a polarizing plate for a liquid crystal display Can be used. Further, the display using this display device is highly reliable, can maintain a high contrast over a long period of time, and is expected to be a display having high color reproducibility.

Claims (11)

A polarizing element comprising a hydrophilic polymer drawn by adsorbing boric acid and containing a substrate having a polarizing function and containing iodine,
In the form of free acid, formula (1):

... (1)
(1), R ₁ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and k, m and n each represent 0 or 1, provided that m + n>
Or a salt thereof,
The visual sensitivity-corrected single-unit transmittance Ys when the base material is measured in a single body is 40.0% to 42.5%
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the unitary transmittance Ts ₄₆₀ of ₄₆₀ nm is 1.2% or less,
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₅₅₀ of ₅₅₀ nm is within 1%
The difference between the visibility-sensitive corrected single-beam transmittance Ys and the single-wavelength transmittance Ts ₆₁₀ of ₆₁₀ nm is within 1%
The visibility-corrected orthogonal transmittance of the two substrates is measured to be orthogonal to the absorption axis direction of not more than 0.01%
Wherein an average value of the orthogonal transmittances Tc Ave 430 to 480 of 430 to 480 nm when the two substrates are measured perpendicular to the absorption axis direction is 0.03% or less. The liquid crystal display according to claim 1, wherein the visibility-corrected parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%
The transmittance Tp ₂₅₅ of ₂₅₅ nm in the case of measuring the parallel transmittance Yp of the substrate and the two substrates parallel to the absorption axis direction satisfy the following formula (2):
0.75 X Yp - 13? Tp ₂₅₅ ? 0.75 X Yp + 1.0 (2)
Of the polarizing element. 3. The liquid crystal display device according to claim 1 or 2, wherein the visibility-corrected parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%
The transmittance Tc ₂₅₅ of ₂₅₅ nm in the case of measuring the parallel transmittance Yp and the two substrates perpendicularly to the absorption axis direction is represented by the following formula (3):
2.OX 10 ^-6 X Yp ^4.1 ? Tc ₂₅₅ ? 2.0 X 10 ^-6 X Yp ^4.4 (3)
Of the polarizing element. 4. The liquid crystal display device according to any one of claims 1 to 3, wherein the visual sensitivity correction parallel transmittance Yp in the case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%
Wherein the difference between the parallel transmittance Yp and the parallel transmittance Tp ₄₆₀ of 460 nm measured when the two substrates are measured parallel to the absorption axis direction is within 3%. The liquid crystal display device according to any one of claims 1 to 4, wherein the visibility-corrected transmittance Yp in a case where the two substrates are measured parallel to the absorption axis direction is in the range of 33% to 37%
The transmittance Tp ₂₉₅ of 295 nm when measured with the parallel transmittance Yp and the two substrates parallel to the absorption axis direction satisfies the following formula (4)
Wherein the parallel transmittance Yp and the transmittance Tp ₃₆₀ of 360 nm measured when the two substrates are parallel to the absorption axis direction satisfy the following formula (5).
1.05 X Yp - 26? Tp ₂₉₅ ? 1.05 X Yp - 13 Equation (4)
1.25 X Yp - 26.25? Tp ₃₆₀ ≤ 1.25 X Yp - 16.25 (5) 6. The liquid crystal display device according to any one of claims 1 to 5, wherein the transmittance Tc ₂₉₅ of 295 nm when the two substrates are measured perpendicularly to the absorption axis direction satisfies the formula (6)
A polarizing element characterized in that the transmittance Tc ₃₆₀ of 360 nm in the case of measuring the two substrates parallel to the absorption axis direction satisfies the formula (7);
2.OX 10 ^-30 x Yp ^18.6 ? Tc ₂₉₅ ? 2.OX 10 ^-30 X Yp ^19.4 Equation (6)
4.OX 10 ^-37 X Yp ^{22 .12} ? Tc ₃₆₀ ? 4.OX 10 ^-37 X Yp ^{22 . 67} (7) The optical sheet according to any one of claims 1 to 6, wherein the transmittance Tc ₄₆₀ of 460 nm when measured with the two substrates being orthogonal to the absorption axis direction Is not more than 0.035%, and
Wherein a transmittance Tc ₆₁₀ of ₆₁₀ nm is 0.01% or less when measured by making two of the substrates orthogonal to the absorption axis direction. The film according to any one of claims 1 to 7, wherein the substrate comprises a polyvinyl alcohol-based resin film,
Wherein the polyvinyl alcohol-based resin film has a degree of polymerization of 3000 to 7000. A polarizing plate comprising a polarizing element according to any one of claims 1 to 8 and provided on at least one surface thereof with a support film. 9. A liquid crystal display device comprising the polarizing element according to any one of claims 1 to 8 or the polarizing plate according to claim 9. A process for producing a polarizing element comprising a hydrophilic polymer drawn by adsorbing boric acid and containing a substrate having a polarizing function containing iodine,
(i) a step of adding a dichroic dye to a polyvinyl alcohol-based resin film to obtain a film containing a dichroic dye,
(ii) a step of stretching a film containing the dichroic dye to obtain a stretched film,
(iii) providing the stretched film to a post-treatment using a solution containing chloride or an iodide,
(iv) after the post-treatment, drying the film to obtain the substrate,
The concentration of the chloride-containing solution or iodide-containing solution is 0.1 to 15% by weight,
The following formula (1)
... (1)
By weight of the organic compound.