TW201700623A - Polarizer and polarizing plate - Google Patents

Abstract

To make it possible to display an achromatic white color when absorption axes of polarizing elements are arranged in parallel with each other and to display an achromatic black color when the absorption axes are arranged orthogonal to each other, while maintaining a high transmittance and a high contrast. By varying the compounding ratio between iodine and an azo compound having a specific structure, the color hue of a polarizing element or a polarizing plate can be adjusted in such a manner that, with respect to an a* value and a b* value as prescribed in JIS Z 8729, the absolute values of the a* value and the b* value can fall within 1 when the transmittance is measured on the polarizing element alone or the polarizing plate alone, the absolute values of the a* value and the b* value can fall within 2 when the transmittance is measured on two of the base materials while setting the absorption axes of the base materials in parallel with each other, and the absolute values of the a* value and the b* value can fall within 2 when the transmittance is measured on two of the base materials while setting the absorption axes of the base materials orthogonal to each other.

Description

Polarizing element, and polarizing plate

The present invention relates to a polarizing element comprising iodine and an azo compound, and a polarizing plate.

The polarizing element is usually produced by adsorbing an iodine or a dichroic dye which is a dichroic dye to a polyvinyl alcohol resin film. A protective film containing triacetyl cellulose or the like is bonded to at least one surface of the polarizing element via a pressure-sensitive 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 referred to as an iodine-based polarizing plate, and a polarizing plate using a dichroic dye as a dichroic dye is referred to as a dye-based polarizing plate. Among these, the dye-based polarizing plate is characterized by high heat resistance, high moist heat durability, high stability, and high selectivity by blending color, and on the other hand, if it is combined with an iodine-based polarizing plate Compared with a polarizing plate having the same degree of polarization, the transmittance is low, that is, there is a problem that the contrast is low. Therefore, it is expected to maintain high durability, various color selectivity, and high polarization characteristics with higher transmittance. However, even in the case of a dye-based polarizing plate having such a wide variety of colors, the polarizing element has hitherto been disposed in parallel with respect to the absorption axis, and when white is displayed, a yellow polarizing element is exhibited. When a polarizing plate that suppresses the yellow hue when it is arranged in parallel is formed in order to improve the yellow hue in the parallel arrangement, the polarizing element may be colored in black when it is placed on the orthogonal axis with respect to the absorption axis. problem. In order to manufacture an achromatic polarizing plate, it is necessary to have no dependence on each wavelength in parallel and orthogonal positions, and it is a fixed transmittance, but such a polarizing plate has not been obtained so far.

The reason why the parallel bit and the orthogonal bit color are different in this way is that even if a dichroic dye is used for the polarizing element, the same wavelength dependence is not exhibited in the parallel position and the orthogonal position, that is, the dichroism is not fixed. And the transmittance of each wavelength is not fixed.

Here, the respective wavelength dependence of the iodine-based polarizing plate will be described. When polyvinyl alcohol (hereinafter, abbreviated as PVA) is used as a substrate and iodine is used as a dichroic dye, it generally has absorption centering on 480 nm and 600 nm. The absorption at 480 nm is said to result from a complex of polyiodide I ₃ ^- and PVA, and the absorption at 600 nm results from a complex of polyiodide I ₅ ^- and PVA. Based on the degree of polarization for each wavelength, with a polyiodide I ₅ ^- compared with complexes of PVA, based on _{multi-3-iodo-I} ^- the polarization degree of the PVA complexes of higher. In this case, if the transmittance is fixed at the orthogonal position of each wavelength, the transmittance in the parallel position is higher at 600 nm with respect to 480 nm, and the parallel position is colored yellow. On the other hand, if the transmittance is fixed in the parallel position, the transmittance in the orthogonal position is lower at 600 nm with respect to 480 nm, and thus the orthogonal bit is colored blue. Further, since there is no absorption based on 550 nm which is high in visibility, color control is difficult. That is, since the degree of polarization (two color ratio) of each wavelength is not fixed, wavelength dependence occurs. In this case, even if it is not an iodine-based polarizing plate, the wavelength dependence of the azo compound having dichroism is similar to the parallel position and the orthogonal position, and generally the same hue is not displayed in the parallel position and the orthogonal position. Pigment.

Heretofore, according to the kind of the azo compound having a general dichroism, there is also an azo compound which exhibits a yellow color in the parallel position and a blue color in the orthogonal position equal to the wavelength dependence of the orthogonal position and the parallel position. Further, it is also known that, depending on the case of polarized light, the degree of sensitivity to the difference between the orthogonal position and the parallel position is different. Therefore, even if the color correction is performed, color correction suitable for sensitivity is required. If the transmittance of each wavelength is not substantially constant in the parallel and orthogonal positions, it is not possible to achieve a transmittance dependence of each wavelength at a fixed value. Moreover, it is necessary to use a polarizing element or a polarizing plate to satisfy the fixed transmittance dependency in parallel and orthogonal positions, and to have high transmittance and high contrast, the polarization (dichromatic ratio) of each wavelength must be fixed. set. When only one azo compound is applied to a polarizing element, the wavelength dependence of the orthogonal bit and the parallel bit is also different. In addition, in the case of blending, if each parallel position and positive are not precisely controlled The relationship between the transmittance of the intersection and the dichroic ratio, and the degree of polarization is high, the achromatic polarizing plate of the present application cannot be achieved. Accordingly, it is extremely difficult to obtain an achromatic polarizing plate, and only the three primary colors of color can be used, which cannot be achieved. When the parallel and orthogonal bits are controlled to be fixed, the polarization of each wavelength must be the same, which is very difficult.

Therefore, as a polarizing element, it is desired to display an achromatic white color when displaying white and a black color polarizing plate when displaying black. However, it has been difficult to achieve a single body transmittance of 35% or more until white is displayed. Achromatic white is displayed, and an achromatic black polarizing element or a polarizing plate is displayed when black is displayed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 4281261

[Patent Document 2] Japanese Patent No. 3357803

[Non-patent literature]

[Non-Patent Document 1]

The first print edition of the application of functional pigments, CMC Publishing (shares), edited by Jiang Zhenghao, p98~100

As a method of improving the hue of the polarizing plate, a technique such as Patent Document 1 or Patent Document 2 is disclosed. Patent Document 1 discloses a polarizing plate that calculates a neutral coefficient and has an absolute value of 0 to 3. However, according to the embodiment, even if the neutral coefficient (NP) is low, only the parallel position obtained in accordance with JIS Z 8729 is used. The hue, a* value is -2 to -1, and the b* value is from 2.5 to 4.0, from which it can be seen that the color is yellow-green when displayed in white. Also, regarding the hue of the orthogonal bits, the a* value is 0 to 1, but the b* value is -1.5 to -4.0, so that it becomes a blue-polarized light. board. Patent Document 2 discloses a polarizing element in which a transmittance of 410 nm to 750 nm is within ±30% of an average value, and a direct dye, a reactive dye, or an acid dye is added in addition to iodine, but it is a separate body. The transmittance, that is, when the color measured by using only one polarizing element is obtained by using the a value of the UCS color space and the b value as the absolute value of 2, it is not necessary to use two polarizing plates for white display (parallel case). When the color of the black display (the case of the orthogonality) is the same, the a value and the b value are expressed as a polarizing element of 2 or less, and the polarizing element which does not represent the achromatic color in the orthogonal position and the parallel position. Further, according to the examples, the individual transmittance is 31.95% in the first embodiment and 31.41% in the second embodiment, and the transmittance is low. Therefore, in the field of high transmittance and high contrast, especially liquid crystal. In the fields of display devices and organic electroluminescence, it is not sufficient for higher transmittance and higher polarization.

The present inventors have made an effort to solve the above problems, and as a result, it has been newly found that the transmittance is fixed in the parallel and orthogonal positions, and the wavelength dependence is eliminated, thereby making the polarization of the parallel and orthogonal positions of the respective wavelengths. (two-color ratio) is fixed, has a high degree of polarization, and even if the transmittance is high, in order to maintain the relationship, only a specific azo compound can be blended, and as a result, high contrast can be achieved, even if it is high. The transmittance also has a high degree of polarization, and the parallel and orthogonal positions can collectively exhibit achromatic polarizing elements. That is, a polarizing element having a single body transmittance of 35% to 45%, which is characterized in that it is a substrate containing iodine and a specific azo compound, and is a* value obtained in accordance with JIS Z 8729, and In the b* value, the a* value and the b* value when the individual body transmittance is measured are 1 or less in absolute value, and the a* value obtained by measuring the two substrates in parallel with respect to the absorption axis direction and The b* value is 2 or less in absolute value, and the a* value and the b* value obtained by orthogonally measuring and measuring two substrates with respect to the absorption axis direction are 2 or less in absolute value, and the polarizing element has The higher transmittance can exhibit an achromatic white color when the absorption axis of the polarizing element is disposed in parallel, and an achromatic black color can be exhibited when the absorption axis of the polarizing element is orthogonally disposed.

That is, the present invention relates to

(1) A polarizing element comprising a substrate containing iodine and an azo compound, wherein the azo compound is a) an azo compound represented by the formula (1) and a formula (2) a combination of an azo compound or a combination of b) an azo compound represented by the formula (1) and an azo compound represented by the formula (3), a salt thereof, or a transition metal complex thereof; According to the a* value and the b* value obtained by JIS Z 8729, the a* value and the b* value when the transmittance of the individual body are measured are 1 or less in absolute value, and two substrates are absorbed relative to each other. The a* value and the b* value obtained by parallel measurement and measurement, and the b* value are 2 or less in absolute value, and the a* value and b* value obtained by orthogonally measuring the two substrates with respect to the absorption axis direction are measured. In the absolute value of 2 or less, the individual body transmittance is 35% to 45%. (A ₁ represents a phenyl group having a substituent or a naphthyl group, and R ₁ or R ₂ each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group, X ₁ represents an amine group which may have a substituent, a benzylamino group which may have a substituent, an aminobenzamide group which may have a substituent, a phenylamine group which may have a substituent, and a benzene which may have a substituent Alkyl group) [Chemical 2] (wherein A ₂ and A ₃ each independently represent a phenyl group having a substituent or a naphthyl group, and at least one of the substituents is a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, and a sulfo group; a lower alkoxy group, a carboxyl group, a nitro group, an amine group, or a substituted amine group, and R ₃ and R ₄ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group. base) (wherein A ₄ represents a nitro group or an amine group, R ₉ represents a hydrogen atom, a hydroxyl group, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group, and X ₂ represents a substituent group; (2) The polarizing element according to (1), wherein the polarizing element is 99% or more; (3) as (1) or (2) The polarizing element according to the present invention is characterized in that the transmittance of each wavelength when the direction of the vibration of the absolute polarization light is irradiated to the absorption axis direction of the polarizing element is polarized light in the orthogonal direction, and the average transmittance of 550 nm to 600 nm is 400 nm. The difference between the average transmittance of 460 nm is within 4%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is within 3%, and further, the vibration of the absolute polarization light is irradiated to the absorption axis direction of the polarizing element. The transmittance at each wavelength when the direction is the polarized light in the parallel direction, the difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is within 1%, and the average transmittance of 600 to 670 nm is 550 to 600 nm. The difference between the average transmittances is within 1%; (4) the deviations recorded in (1) to (3) An element comprising: a base material comprising a polyvinyl alcohol resin film; and (5) a polarizing plate obtained by providing a support film on at least one side of the polarizing element according to any one of (1) to (4). (6) A liquid crystal display device using the polarizing element according to (1) to (4) or the polarizing plate according to (5).

The polarizing element of the present invention has a high transmittance, and can exhibit achromatic white when the absorption axis of the polarizing element is disposed in parallel, and can exhibit achromatic black when the absorption axis of the polarizing element is orthogonally disposed. .

The invention is characterized in that a polarizing element having a single body transmittance of 35% to 45% includes a substrate containing a dichroic dye containing iodine and a specific azo compound, and is obtained according to JIS Z 8729. In the obtained a* value and b* value, the a* value and the b* value when the individual transmittance is measured are 1 or less in absolute value, and two substrates are measured in parallel with respect to the absorption axis direction. The obtained a* value and the b* value are within 2 in absolute value, and the a* value and the b* value obtained by orthogonally measuring the two substrates with respect to the absorption axis direction are 2 in absolute value. Within. The representation of the object color specified in JIS Z 8729 is equivalent to the representation of the object color specified by the International Commission on Illumination (CIE). The individual transmittance is a transmittance when measuring the transmittance of the single sheet (single body) when the natural light is projected onto the polarizing element. Since the element is achromatic, the hue of the single body transmittance is required to be a*. Value (hereinafter, expressed as a* - s), and b* value (hereinafter, expressed as a* - s) in absolute terms Within 1. In addition, when the natural light is incident, the a* value (hereinafter referred to as a*-p) and the b* value (hereinafter referred to as b*-p) obtained by measuring the two substrates in parallel with respect to the absorption axis direction are measured. The absolute value is 2 or less, and when the natural light is incident, the a* value (hereinafter referred to as a*-c) and the b* value obtained by orthogonally measuring the two substrates with respect to the absorption axis direction are measured. (hereinafter, referred to as b*-c) is 2 or less in absolute value, whereby a polarizing plate which can exhibit achromatic color in parallel position can be realized. More preferably, the absolute values of a*-p and b*-p are within 1.5, and the absolute values of a*-c and b*-c are preferably within 1.5, and further preferably a*-p and b*- The absolute value of p is within 1.0, and the absolute value of a*-c and b*-c is preferably within 1.0. As the absolute values of a*-p and b*-p, even if the absolute value is only 0.5, the difference in color can be felt as the sensitivity of the person, so it is very important to control a* and b*. In particular, as the absolute values of a*-p and b*-p, if the individual body, the parallel position, and the orthogonal bit are each within one, the case where the color is substantially white and the color is set to black is It is almost impossible to confirm and becomes a good polarizing element.

As the performance of the polarizing element, the transmittance is high and the degree of polarization is also high. When the individual transmittance is 35%, the brightness can be expressed even when used in a display device, and is preferably 38% or more, more preferably 39% or more, and still more preferably 40% or more. When the degree of polarization is 99% or more, a polarizing function can be exhibited as a display device. However, a polarizing plate having a higher contrast ratio is preferable, and a polarizing element of 99.9% or more, more preferably 99.95% or more is more preferable.

In order to obtain the a* value and the b* value obtained in accordance with JIS Z 8729, the a* value and the b* value in the case of measuring the transmittance of the individual body are within 1 of the absolute value, and two sheets are used. The a* value and the b* value obtained by measuring the parallel direction of the absorption axis in the direction of the absorption axis are 2 or less in absolute value, and the a* value obtained by measuring the two substrates perpendicular to the absorption axis direction and measuring the same And a polarizing element having a b* value of 2 or more in an absolute value of 2 or more in absolute value can be realized by including an iodine compound having a specific combination with iodine or the following. In the case of containing iodine, only iodine is difficult to dissolve in the solvent, and it is difficult to be impregnated into the base. In the case of materials, iodides such as potassium iodide, copper iodide, sodium iodide, and calcium iodide, and chlorides such as sodium chloride, lithium chloride, and potassium chloride are usually used.

The substrate is formed by forming a material containing a hydrophilic polymer, and may contain iodine or various azo compounds described in Non-Patent Document 1. The hydrophilic polymer is not particularly limited, and examples thereof include a polyvinyl alcohol resin, an amylose resin, a starch resin, a cellulose resin, and a polyacrylate resin. In the case of containing a dichroic dye, it is preferably a resin containing a polyvinyl alcohol-based resin and a derivative thereof, depending on workability, dyeability, and crosslinkability. These resins may be formed into a film shape containing the dye of the present invention and a formulation thereof, and subjected to alignment treatment such as stretching to prepare a polarizing element or a polarizing plate.

The polarizing element of the present invention may be a combination of a) an azo compound represented by the formula (1) and an azo compound represented by the formula (2), or b) an azo compound represented by the formula (1) and a formula (3). A combination of a compound represented by the azo compound shown, a salt thereof, or a transition metal complex thereof, and iodine are impregnated on a substrate. Hereinafter, the azo compounds represented by the formulae (1) to (3) will be described.

In the formula (1), A ₁ represents a phenyl group having a substituent or a naphthyl group, and each of R ₁ or R ₂ independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower group having a sulfo group. Alkoxy group, X ₁ represents an amine group which may have a substituent, a benzylamino group which may have a substituent, an aminobenzamide group which may have a substituent, a phenylamine group which may have a substituent, or A phenyl azo group which may have a substituent. X _{1 is} preferably an amine group which may have a substituent, a benzylamino group which may have a substituent, or a phenylamine group which may have a substituent, and more preferably X ₁ is a phenylamine which may have a substituent The base is preferably further, and it is preferred that A ₁ is a phenyl group having a substituent, and a polarizing element of the present application having a higher degree of polarization can be produced, which is preferable. Further, the so-called lower order of the lower alkyl group and the lower alkoxy group of the present application means a carbon number of 1 to 3.

In the case of the formula (1), when A ₁ specifically represents a phenyl group having a substituent, examples of the substituent on the phenyl group of A ₁ include a sulfo group, a lower alkyl group, a lower alkoxy group, and a sulfonate. a lower alkoxy group, a carboxyl group, a nitro group, an amine group, or a substituted amine group. A ₁ preferably has at least one sulfo group as a substituent. Further, in the case of having two or more substituents, one of the substituents is a sulfo group or a carboxyl group, preferably a sulfo group, and as other substituents, a sulfo group, a lower alkyl group, a lower alkoxy group is preferred. a lower alkoxy group having a sulfo group, a carboxyl group, a nitro group, an amine group, or a substituted amine group. As the above lower alkoxy group having a sulfo group, a linear alkoxy group is preferred, and the substitution position of the sulfo group is preferably an alkoxy terminal, more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group. base. The substituted amino group may, for example, be an ethoxymethyl group or the like. Among the above other substituents, a sulfo group, a lower alkyl group or a lower alkoxy group is more preferable. The number of substituents on the phenyl group of A ₁ is preferably 1 or 2, and the position of substitution is not particularly limited, and a combination of the 2-position and the 4-position is preferred. In the case where A ₁ represents a naphthyl having a substituent of the group, the naphthyl represented by A ₁ as the substituents on the group include a sulfo group containing no hydrogen atoms, hydroxyl, amino, substituted amino, nitro, The amidino group or the alkoxy group having a sulfo group having 1 to 5 carbon atoms is preferably a sulfo group, a hydroxyl group or an alkoxy group having a sulfo group having 1 to 5 carbon atoms. The substituent on the naphthyl group represented by A ₁ preferably has at least one sulfo group. When the naphthyl group represented by A ₁ has two or more substituents, one of the substituents is a sulfo group, and the other substituents are preferably selected from a sulfo group, a hydroxyl group, and a carbon group having a sulfo group. At least one of the groups consisting of 1 to 5 alkoxy groups. The alkoxy group having a sulfo group having 1 to 5 carbon atoms is preferably a linear alkoxy group having a sulfo group having 1 to 5 carbon atoms, more preferably a carbon having a sulfo group at the terminal of the alkoxy group. The number is a linear alkoxy group of 1 to 5, and more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group. The naphthyl group represented by A ₁ is preferably selected from the group consisting of a naphthyl group substituted with 2 or 3 sulfo groups, or a group consisting of a hydroxyl group, a 3-sulfopropoxy group, and a 4-sulfobutoxy group. The naphthyl group substituted with at least 1 group and 1 or 2 sulfo groups is more preferably a naphthyl group substituted with 2 or 3 sulfo groups, or a 3-sulfopropoxy group and a sulfo group-substituted naphthyl group. Further, it is further preferably a disulfonaphthyl group or a trisulfonaphthyl group, and most preferably a trisulfonaphthyl group. The preferred substitution positions of the substituents on the naphthalene ring are 1 position and 3 positions in the case where the substituent is two, and 1 position, 3 position and 6 position in the case where the substituent is three. The substitution position of the azo group of the naphthyl group is preferably 2 positions.

X ₁ specifically represents an amine group which may have a substituent, a benzylamino group which may have a substituent, an aminobenzyl benzylamino group which may have a substituent, a phenylamine group which may have a substituent, or may have a substitution Phenyl azo group. When X ₁ may have a substituent, for example, a benzylideneamino group, a phenylamino group, or a phenylazo group, the substituent is preferably a lower alkyl group, a lower alkoxy group, a hydroxyl group, a carboxyl group, or the like. The sulfo group, the amine group or the substituted amine group, and examples of the substituted amine group include an ethyl hydrazino group. In the case where X ₁ is a phenylamino group which may have a substituent, the substituent is a methyl group, a methoxy group, an amine group, a substituted amine group, preferably an ethyl hydrazino group or a sulfo group, more preferably It is a methyl group, a methoxy group or an amine group. The number of the substituents on the phenyl group and the position of substitution are not particularly limited. In general, the number of the substituents is preferably from 0 to 2. In the case where a substituent other than hydrogen is present, it is preferred that at least one substituent is present in the para position with respect to the bonding position to the amine group. Examples of the phenylamine group which may have a substituent include a phenylamino group, a 4-methylphenylamino group, a 4-methoxyphenylamino group, a 4-aminophenylamino group, and 4 Amino-2-sulfophenylamino, 4-amino-3-sulfophenylamino, 4-sulfomethylaminophenylamino or 4-carboxyethylaminophenylamino Wait. Among these, an unsubstituted phenylamino group and a p-methoxyphenylamino group are more preferred. In the case where X ₁ is a benzylamino group which may have a substituent, the substituted amino group exemplified as the amine group or the ethyl hydrazino group as the substituent is preferably a hydroxyl group, more preferably an amine group and The substituted amine group exemplified for the ethenylamino group is further preferably an amine group. The number of the substituent on the phenyl group is usually from 0 to 1, and the position of substitution is not particularly limited, and in the case of a substituent other than a hydrogen atom, it is preferably para. In the case where X ₁ is a benzylamino group, the substituent represents a hydrogen atom, a hydroxyl group, an amine group or a substituted amine group, and a substituted amino group exemplified as a hydrogen atom, an amine group or an ethyl hydrazino group is preferred. The position as a substituent is preferably a para position. Examples of the benzamidine amine group include a benzammonium group, a 4-aminobenzimidamide group, a 4-hydroxybenzamide group or a 4-(3-carboxy-1-acetoxypropyl group). Aminoamino)benzamide, 4-(2-methoxycarbonyl-1-oxoethylamino)benzamide, and the like. More preferably, the benzinamide group is an aminobenzimidamide group. In the case where X ₁ is a phenylazo group which may have a substituent, examples of the substituent include a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an amine group. Or a substituted amino group, preferably a hydroxyl group, an amine group, a methyl group, a methoxy group or a carboxyl group, more preferably a hydroxyl group. The number of substituents is usually from 0 to 3, preferably from 1 to 2. Examples of the phenylazo group include a 2-methylphenylazo group, a 3-methylphenylazo group, a 2,5-dimethylphenylazo group, and a 3-methoxyphenyl group. Azo, 2-methoxy-5-methylphenylazo, 2,5-dimethoxyphenylazo, 4-aminophenylazo, 4-hydroxyphenyl Nitrogen or 4-carboxyethylaminophenylazo, etc., preferably 4-aminophenylazo, 4-hydroxyphenylazo or 4-carboxyethylaminophenylazo base.

Next, the formula (2) will be described.

In the formula (2), A ₂ and A ₃ each independently represent a phenyl group having a substituent or a naphthyl group, and at least one of the substituents is a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, and a lower alkoxy group, a carboxyl group, a nitro group, an amine group or a substituted amine group of a sulfo group, each of R ₃ and R ₄ independently representing a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a sulfo group. Lower alkoxy. Preferably A _2, A ₃ are each independently a naphthyl group, more preferably A ₂ and A ₃ are a naphthyl group of a sulfo group, and further preferably R _3, R ₄ are each independently lower alkoxy, since It is preferred to produce a polarizing element of the present application having a higher degree of polarization.

Next, the formula (3) will be described.

In the formula (3), A ₄ represents a nitro group or an amine group, and R ₉ represents a hydrogen atom, a hydroxyl group, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group, and X ₂ represents that it may have An amine group of a substituent, a phenylamine group which may have a substituent. Preferably, A _{4 is} preferably a nitro group, and further preferably R ₉ is a lower alkoxy group, which is preferred because it can produce a polarizing element of the present application having a higher degree of polarization. Further, the azo compound of the formula (3) may be in the form of a salt or a complex compound, and in particular, it is preferably in the case of a transition metal complex formed by a metal such as copper.

As the azo compound, an azo compound may be added to the extent that the properties of the present application are not impaired for color correction. Especially good for those with higher dichroism. For example, an azo compound shown in Non-Patent Document 1, CI Direct Yellow 12, CI Direct Yellow 28, CI Direct Yellow 44, CI Direct Orange 26, CI Direct Orange 39, CI Direct Orange 107, CI Direct Red 2, CI Direct Red 31, CI Direct Red 79, CI Direct Red 81, CI Direct Red 247, CI Direct Green 80, CI Direct Green 59, and Japanese Patent Special Public Show No. 64-5623, Japanese Patent Special Open No. 3-12606, Japan An azo compound or the like is disclosed in JP-A-2001-33627, JP-A-2002-296417, and JP-A-60-156759. In particular, an azo compound having a phenyl J acid on a trisazo structure can be suitably used, and it is particularly preferable to use the azo compound of Japanese Patent Laid-Open No. Hei 3-12606 and the formula (1) to (3) of the present invention. The azo compound is used together for the polarizing element, and is particularly suitable for the trisazo An azo compound of an azo compound having a structure of a phenyl J acid of the Japanese Patent Laid-Open No. Hei 3-12606 is used together with the iodine of the present invention, the azo compound of the formula (1), and the azo compound of the formula (3). Polarized component. These azo compounds may be used in the form of an alkali metal salt (for example, a Na salt, a K salt, a Li salt), an ammonium salt, or an amine salt in addition to the free acid. However, the azo compound is not limited to these, and a known azo compound having dichroic property can be used. The azo compound particularly enhances optical properties by being a free acid, a salt thereof, or a copper complex salt thereof dye. The azo compound may be used alone or in combination with other azo compounds, and the formulation is not limited. By using the dye as the azo compound and adjusting the transmittance of the polarizing element, it is possible to measure a* of the individual transmittance in the a* value and the b* value obtained in accordance with JIS Z 8729. The value and the b* value are within 1 of the absolute value, and the a* value and the b* value obtained by measuring the two substrates in parallel with respect to the absorption axis direction are 2 or less in absolute value, so that 2 pieces are made. The base material obtained by measuring the a* value and the b* value of the base material orthogonally to the absorption axis direction in an absolute value of 2 or less is a polarizing element having a single body transmittance of 35% to 45%.

In order to obtain the a* value and the b* value obtained in accordance with JIS Z 8729, the a* value and the b* value in the case of measuring the transmittance of the individual body are within 1 of the absolute value, and two sheets are made. The a* value and the b* value obtained by parallel measurement with respect to the direction of the absorption axis are 2 or less in absolute value, and the a* value obtained by measuring the two substrates perpendicular to the absorption axis direction and measuring And a polarizing element having a b* value of 2 or more in an absolute value of 2 or more in absolute value can be easily realized by controlling the transmittance of each wavelength. In the control method, the transmittance of each wavelength of the polarized light of approximately 100% of the polarized light (hereinafter referred to as absolute polarized light) in the direction of the absorption axis of the substrate (polarizing element) is polarized light in the orthogonal direction, The difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is controlled to be within 4%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is controlled to be within 3%, and further The wavelength at which the direction of the absorption axis of the substrate polarizing element is irradiated with the polarized light in the direction in which the direction of the absolute polarized light is parallel Transmittance, the difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is controlled to be within 1%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is adjusted to 1%. Within this, it can be easily realized.

Further preferably, the transmittance of each wavelength when the direction of the vibration of the absolute polarized light is orthogonal to the polarized light is controlled, and the difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is controlled to be within 3.5%. And controlling the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm to be within 2.5%, and further preferably for each wavelength when the polarization direction of the irradiation of the absolute polarization light is the polarization direction of the orthogonal direction The transmittance, the difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is controlled to be within 3.0%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is controlled to 2.0%. Within.

The method of obtaining the azo compound represented by the formula (1) can be produced by the method described in JP-A-2003-215338, JP-A-H09-302250, and JP-A No. 3881175, but is not Limited to these. Specific examples of the azo compound represented by the formula (1) include an azo compound of the formula (2) described in CI Direct Red 81, CI Direct Red 117, CI Direct Red 127, and Japanese Patent No. 3881175. A dye described in the formula (1) or the like described in Japanese Patent No. 4034344.

The method for obtaining the azo compound represented by the formula (2) can be obtained, for example, by the method described in WO2012/165223, but is not limited thereto.

The method of obtaining the azo compound represented by the formula (3), for example, the method described in Japanese Patent Laid-Open No. Hei 60-156759, Japanese Patent Application Laid-Open No. Hei No. Hei No. Hei. It is not limited to these.

As a more specific example of the azo compound represented by the formula (1), the following compound examples 1-1 to 1-15 (all of which are represented by the free acid form) are disclosed.

[Compound Example 1-1]

[Chemistry 7]

[Compound Example 1-2]

[Compound Example 1-3]

[Compound Examples 1-4]

[Compound Examples 1-5]

[Compound Examples 1-6]

[Compound Examples 1-7]

[Compound Examples 1-8]

[Chemistry 14]

[Compound Example 1-9]

[Compound Examples 1-10]

[Compound Example 1-11]

[Compound Example 1-12]

[Compound Example 1-13]

[Compound Examples 1-14]

[Compound Examples 1-15]

[Chem. 21]

Next, as a more specific example of the azo compound represented by the formula (2), the following compound examples 2-1 to 2-5 (both in the form of the free acid) are disclosed.

[Compound Example 2-1]

[Compound Example 2-2]

[Compound Example 2-3]

[Compound Examples 2-4]

[Compound Example 2-5]

Further, as a more specific example of the azo compound represented by the formula (3), the following compound examples 3-1 to 3-14 (both in the form of the free acid) are disclosed.

[Compound Example 3-1]

[Compound Example 3-2]

[Compound Example 3-3]

[Compound Example 3-4]

[Compound Example-5]

[Compound Example 3-6]

[化32]

[Compound Example 3-7]

[Compound Example 3-8]

[Compound Example 3-9]

[Compound Example 3-10]

[化36]

[Compound Example 3-11]

[Compound Example 3-12]

[Compound Example 3-13]

[Compound Example 3-14]

Hereinafter, a method of producing a specific polarizing element will be described using a polyvinyl alcohol-based resin film as a substrate as an example. The method for producing the polyvinyl alcohol-based resin is not particularly limited, and it can be produced by a known method. The production method can be obtained, for example, by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 95 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with an aldehyde may be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin means a viscosity average degree of polymerization, which can be determined by a known method in the technical field. It is usually about 1,000 to 10,000, preferably about 1,500 to 6,000.

A film made of the above polyvinyl alcohol-based resin is used as a green film. The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film formation can be carried out by a known method. In this case, glycerin, ethylene glycol, propylene glycol, low molecular weight polyethylene glycol, or the like may be contained as a plasticizer on the polyvinyl alcohol resin film. The plasticizing dose is 5 to 20% by weight, preferably 8 to 15% by weight. The film thickness of the green film containing the polyvinyl alcohol-based resin is not particularly limited, and is, for example, about 5 μm to 150 μm, preferably about 10 μm to 100 μm.

Next, the swelling step was carried out on the green film obtained by the above method. The swelling treatment is applied by immersing in a solution of 20 to 50 ° C for 30 seconds to 10 minutes. The solution is preferably water. The stretching ratio is preferably adjusted within a range of 1.00 to 1.50 times, preferably 1.10 to 1.35 times. In the case where the time for producing the polarizing film is shortened, the swelling is also performed during the dyeing treatment of the dye, so that the swelling treatment may be omitted.

The swelling step is carried out by immersing the polyvinyl alcohol resin film in a solution of 20 to 50 ° C for 30 seconds to 10 minutes. The solution is preferably water. When the time for manufacturing the polarizing element is shortened, the swelling is also performed during the dyeing treatment of the dye, so that the swelling treatment may be omitted.

The dyeing step is carried out after the swelling step. In the dyeing step, iodine and an azo compound represented by the formula (1) to the formula (3) can be used for dyeing. Regarding iodine, iodine may be impregnated into the polyvinyl alcohol-based resin film, and as the impregnation method, a method in which iodine or iodide is dissolved in water and impregnated is preferred. As the iodide, for example, potassium iodide, ammonium iodide, cobalt iodide, zinc iodide or the like can be used, but it is not limited to the iodide shown here. The iodine concentration is 0.0001% by weight to 0.5% by weight, preferably 0.001% by weight to 0.4% by weight, and the iodide concentration is preferably 0.0001% by weight to 8% by weight. The dye described in Non-Patent Document 1 or the azo compound represented by Formulas (1) to (3) can be adsorbed onto the polyvinyl alcohol film by a dyeing step. The dyeing step is not particularly limited as long as the dye is adsorbed on the polyvinyl alcohol film. For example, the dyeing step is carried out by immersing the polyvinyl alcohol resin film in a solution containing a dichroic dye. The temperature of the solution in this step is preferably from 5 to 60 ° C, more preferably from 20 to 50 ° C, and particularly preferably from 35 to 50 ° C. The time of immersion in the solution can be appropriately adjusted, preferably in the range of 30 seconds to 20 minutes, more preferably 1 to 10 minutes. The dyeing method is preferably carried out in the solution, but it can also be carried out by coating the solution on a polyvinyl alcohol resin film. The solution containing the dichroic dye may contain sodium carbonate, sodium hydrogencarbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate or the like as a dyeing auxiliary. The content of these may be adjusted at any concentration depending on the dyeing time and temperature of the dye, and is preferably 0 to 5% by weight, and more preferably 0.1 to 2% by weight, based on the respective contents. As containing iodine and azo compounds The order of the treatment may be carried out at the same time, but it is preferably a dyeing method containing an azo compound after containing iodine from the viewpoint of management or productivity of the dyeing liquid, and more preferably containing the azo compound. The method of iodine. The azo compound may be used in the form of a salt of the compound, in addition to the form of the free acid. Such a salt may also be used in the form of an alkali metal salt such as a lithium salt, a sodium salt or a potassium salt, or an organic salt such as an ammonium salt or an alkylamine salt. It is preferably a sodium salt.

After the dyeing step and before proceeding to the next step, a washing step (hereinafter referred to as washing step 1) may be performed. The washing step 1 is a step of washing the dye solvent adhering to the surface of the polyvinyl alcohol resin film in the dyeing step. By performing the washing step 1, it is possible to suppress the case where the dye migrates to the liquid to be treated next. In the washing step 1, water is usually used. The washing method is preferably immersed in the solution, or may be washed by applying the solution to a polyvinyl alcohol resin film. The washing time is not particularly limited, and is preferably from 1 to 300 seconds, more preferably from 1 to 60 seconds. The temperature of the solvent in the washing step 1 is required to be a temperature at which the hydrophilic polymer does not dissolve. In general, the cleaning treatment is carried out at 5 to 40 °C. However, even without the step of the cleaning step 1, the performance does not cause a problem, so this step can also be omitted.

After the dyeing step or the washing step 1, a step of containing a crosslinking agent and/or a water-resistant agent may be carried out. As the crosslinking agent, for example, a boric acid such as boric acid, borax or ammonium borate, a polyvalent aldehyde such as glyoxal or glutaraldehyde, a polyisocyanate compound such as a biuret type, an isocyanurate type or a block type can be used. A titanium compound such as titanium oxysulfate or the like may be used, and ethylene glycol glycidyl ether or polyamine epichlorohydrin may be used. Examples of the water resistance agent include peroxysuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride or magnesium chloride, and preferably boric acid. . The step of containing a crosslinking agent and/or a water resistance agent using at least one or more kinds of crosslinking agents and/or water resistance agents as described above is carried out. The solvent at this time is preferably water, but is not limited thereto. When the concentration of the crosslinking agent and/or the water-resistant agent in the solvent in the step of containing the crosslinking agent and/or the water-resistant agent is represented by boric acid, the concentration is preferably 0.1 to the solvent. 6.0 weight The amount % is more preferably 1.0 to 4.0% by weight. The solvent temperature in this step is preferably from 5 to 70 ° C, more preferably from 5 to 50 ° C. The method of allowing the polyvinyl alcohol resin film to contain a crosslinking agent and/or a water resistance agent is preferably immersed in the solution, or the solution may be applied or applied to a polyvinyl alcohol resin film. The processing time in this step is preferably from 30 seconds to 6 minutes, more preferably from 1 to 5 minutes. However, it is not necessary to contain a crosslinking agent and/or a water-resistant agent, and when it is intended to shorten the time, when the crosslinking treatment or the water-resistant treatment is not required, the treatment step may be omitted.

After the dyeing step, the washing step 1, or the step of containing a crosslinking agent and/or a water-resistant agent, an extending step is performed. The stretching step is a step of uniaxially stretching the polyvinyl alcohol film. The stretching method may be either a wet stretching method or a dry stretching method, and the stretching ratio is extended by more than three times to reach the cost of the invention. The stretching ratio is 3 times or more, preferably extending to 5 times to 7 times.

In the case of the dry stretching method, when the heating medium is an air medium, the temperature of the air medium is preferably extended at a normal temperature of -180 °C. Further, the humidity is preferably treated in an atmosphere of 20 to 95% RH. Examples of the heating method include an inter-roller region stretching method, a roll heating stretching method, a crucible stretching method, and an infrared heating stretching method. However, the stretching method is not limited. The extending step may be performed in one stage or by extending in a plurality of stages of two or more stages.

In the case of the wet stretching method, stretching is carried out in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferred to carry out the stretching treatment while immersing in a solution containing a crosslinking agent and/or a water-resistant agent. As the crosslinking agent, for example, a boric acid such as boric acid, borax or ammonium borate, a polyvalent aldehyde such as glyoxal or glutaraldehyde, a polyisocyanate compound such as a biuret type, an isocyanurate type or a block type can be used. A titanium compound such as titanium oxysulfate or the like may be used, and ethylene glycol glycidyl ether or polyamine epichlorohydrin may be used. Examples of the water resistance agent include peroxysuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride or magnesium chloride. The stretching is carried out in a solution containing at least one of the above-mentioned crosslinking agents and/or a water-resistant agent. Crosslinker Good is boric acid. The concentration of the crosslinking agent and/or the water resistance agent in the stretching step is, for example, preferably from 0.5 to 15% by weight, more preferably from 2.0 to 8.0% by weight. The stretching ratio is preferably 2 to 8 times, more preferably 5 to 7 times. The extension temperature is preferably treated at 40 to 60 ° C, more preferably 45 to 58 ° C. The extension time is usually 30 seconds to 20 minutes, more preferably 2 to 5 minutes. The wet stretching step can be carried out in one step or by stretching in two or more stages.

After the stretching step, a crosslinking agent and/or a water-resistant agent may be deposited on the surface of the film, or a foreign matter may adhere thereto, so that the surface of the cleaning film may be washed (hereinafter referred to as a cleaning step 2). The washing time is preferably from 1 second to 5 minutes. The washing method is preferably immersed in the washing solution, or may be washed by applying or applying the solution to a polyvinyl alcohol resin film. It can be washed in one stage or in multiple stages of two or more stages. The temperature of the solution in the washing step is not particularly limited and is usually 5 to 50 ° C, preferably 10 to 40 ° C.

Examples of the solvent to be used in the treatment steps up to this include water, dimethyl hydrazine, N-methylpyrrolidone, methanol, ethanol, propanol, isopropanol, glycerin, ethylene glycol, and propylene glycol. An alcohol such as diethylene glycol, triethylene glycol, tetraethylene glycol or trimethylolpropane, or an amine such as ethylenediamine or diethylenetriamine, but is not limited thereto. Further, a mixture of one or more of these solvents may be used. The best solvent is water.

After the stretching step or the washing step 2, a drying step of the film is carried out. The drying treatment can be carried out by natural drying, and in order to further improve the drying efficiency, moisture removal on the surface can be carried out by compression using a roll, an air knife, a suction roll, or the like, and/or air blowing can be performed. The drying treatment temperature is preferably carried out at 20 to 100 ° C, more preferably at 60 to 100 ° C. The drying treatment time can be applied for 30 seconds to 20 minutes, preferably 5 to 10 minutes.

According to the above method, a polarizing element having a single body transmittance of 35% to 45% is obtained, which is characterized in that it comprises an azo compound containing iodine and the formula (1) to formula (3). The base of the dichroic dye, and the a* value and the b* value determined according to JIS Z 8729, the a* value and the b* value when measuring the individual body transmittance are in absolute terms. Within 1 or less, the a* value and the b* value obtained by parallel measurement of the two substrates with respect to the absorption axis direction are 2 or less in absolute value, and the two substrates are orthogonal to the absorption axis direction. The a* value and the b* value obtained by the measurement are in the range of 2 or less in absolute value.

A polarizing plate is produced by providing a transparent protective layer on one side or both sides of the obtained polarizing element. The transparent protective layer may be provided as a coating layer formed of a polymer or as a laminate layer of the film. 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 preferred. Examples of the substance used as the transparent protective layer include a cellulose acetate resin such as triacetonitrile cellulose or diacetyl cellulose or a film thereof, an acrylic resin or a film thereof, a polyvinyl chloride resin or a film thereof, Nylon resin or film thereof, polyester resin or film thereof, polyarylate resin or film thereof, A cyclic olefin such as a olefin is a monomeric cyclic polyolefin resin or a film thereof, polyethylene, polypropylene, having a ring system or a descending The polyolefin of the olefin skeleton or a copolymer thereof, a main chain or a side chain thereof, a resin or a polymer of ruthenium and/or guanamine, or a film thereof. Further, as the transparent protective layer, a resin having a liquid crystal property or a film thereof may be provided. The thickness of the protective film is, for example, about 0.5 μm to 200 μm. A polarizing plate is produced by providing one or more of the same type or different types of resins or films on one side or both sides.

As described above, in order to bond the transparent protective layer to the polarizing element, an adhesive is required. The adhesive is not particularly limited, and is preferably a polyvinyl alcohol adhesive. Examples of the polyvinyl alcohol adhesive include, for example, Gohsenol NH-26 (manufactured by Nippon Synthetic Co., Ltd.) and EXCEVAL RS-2117 (manufactured by Kuraray Co., Ltd.), but are not limited thereto. A crosslinking agent and/or a water resistance agent may be added to the adhesive. A maleic anhydride-isobutylene copolymer is used in the polyvinyl alcohol adhesive, and an adhesive mixed with a crosslinking agent may be used as needed. Examples of the maleic anhydride-isobutylene copolymer include Isobam #18 (manufactured by Kuraray Co., Ltd.), Isobam #04 (manufactured by Kuraray Co., Ltd.), ammonia-modified Isobam #104 (manufactured by Kuraray Co., Ltd.), and ammonia-modified Isobam # 110 (manufactured by Kuraray Co., Ltd.), yttrium imidized Isobam #304 (manufactured by Kuraray Co., Ltd.), yttrium imidized Isobam #310 (manufactured by Kuraray Co., Ltd.), and the like. A water-soluble polyvalent epoxy compound can be used in the crosslinking agent at this time. Examples of the water-soluble polyvalent epoxy compound include DENACOL EX-521 (manufactured by Nagase ChemteX Co., Ltd.), Tetrad-C (manufactured by Mitsui Gas Chemical Co., Ltd.), and the like. Further, as an adhesive other than the polyvinyl alcohol resin, a known binder of an urethane type, an acrylic type or an epoxy type can also be used. Further, in order to increase the adhesion of the adhesive or to improve the water resistance, an additive such as a zinc compound, a chloride or an iodide may be contained at a concentration of about 0.1 to 10% by weight. There is no limitation on the additive. After the transparent protective layer is bonded by an adhesive, a polarizing plate is obtained by drying or heat treatment at a suitable temperature.

The obtained polarizing plate is attached to a display device such as a liquid crystal or an organic electroluminescence as the case may be, and may be provided on the surface of the protective layer or film which is a non-exposed surface to improve the viewing angle and/or contrast. Various functional layers, layers or films having brightness enhancement. In order to bond the polarizing plate to the film or display device, it is preferred to use an adhesive.

Further, various functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer may be provided on the other surface of the polarizing plate, that is, the protective layer or the exposed surface of the film. In order to produce a layer having such various functionalities, a coating method is preferred, and a film having this function may be bonded via an adhesive or an adhesive. Further, the various functional layers may be a layer or a film that controls the phase difference.

According to the above method, the a* value and the b* value in the case of measuring the transmittance of the individual body in the a* value and the b* value obtained in accordance with JIS Z 8729 can be obtained within 1 of the absolute value. The two a* values and the b* value obtained by measuring the two substrates in parallel with respect to the absorption axis direction were 2 or less in absolute value, and the two substrates were orthogonal to the absorption axis direction and measured. The obtained a* value and the b* value are polarizing elements having a single body transmittance of 35% to 45% in an absolute value of 2 or less, and a polarizing plate. A liquid crystal display device using the polarizing element or the polarizing plate of the present invention has a high reliability and a liquid crystal display device having high contrast and high color reproducibility for a long period of time.

The polarizing element or the polarizing plate of the present invention thus obtained is provided with a protective layer, a functional layer, a support, and the like as needed, and is used for a liquid crystal projector, a calculator, a clock, a notebook computer, Word processor, LCD TV, polarized lens, polarized glasses, car navigation, and indoor and outdoor measuring instruments or displays. In particular, it can be used as an effective polarizing element or a polarizing plate in a reflective liquid crystal display device, a semi-transmissive liquid crystal display device, organic electroluminescence or the like.

As a method of applying the polarizing plate of the present invention, it can also be used as a polarizing plate with a support. Since the support is attached to the polarizing plate, it preferably has a flat portion, and is preferably a glass molded article because it is used for optical purposes. Examples of the glass molded article include a glass plate, a lens, a crucible (for example, triterpene, cubic crucible), and the like. A polarizing plate attached to a lens can be used as a condensing lens with a polarizing plate in a liquid crystal projector. Further, a polarizing plate attached to the cymbal can be used as a polarizing beam splitter with a polarizing plate or a two-color ray with a polarizing plate in a liquid crystal projector. Moreover, it can also be attached to a liquid crystal cell. Examples of the material of the glass include inorganic glass such as soda glass, borosilicate glass, inorganic substrate containing crystal, inorganic substrate containing sapphire, or an organic plastic plate such as acrylic or polycarbonate. It is an inorganic glass. The thickness or size of the glass plate can be the desired size. Further, in order to further increase the light transmittance of the single plate on the polarizing plate with glass, it is preferable to provide an AR layer on one surface or both surfaces of the glass surface or the polarizing plate surface. On such a support, for example, a transparent adhesive (adhesive) is applied to the plane of the support, and then the polarizing plate of the present invention is attached to the coated surface. Further, a transparent adhesive (adhesive) may be applied to the polarizing plate, and then the support may be attached to the coated surface. The adhesive (adhesive) used herein is preferably, for example, an acrylate. In the case where the polarizing plate is used as an elliptically polarizing plate, the phase difference plate side is usually attached to the support side, and the polarizing plate side may be attached to the glass molded article.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited thereto. Further, the evaluation of the transmittance shown in the examples was carried out as follows.

When the transmittance of each wavelength when measuring one polarizing element or a polarizing plate is the transmittance Ts, the two polarizing elements or the polarizing plate are stacked in the same direction of the absorption axis. The transmittance of each wavelength is set to the parallel bit transmittance Tp, and the transmittance of each wavelength when the two polarization plates are overlapped so that the absorption axis is orthogonal is set to the orthogonal bit transmittance Tc, which is based on the C light source. The transmittance of the 2° field of view chromaticity function for the visibility correction is set to Ys, the parallel transmittance corrected by the visibility is set to Yp, and the orthogonal transmittance of the visibility correction is set to Yc, and the spectrophotometer is used [Hitachi Manufacturing Co., Ltd. "U-4100" manufactured by the company is measured at intervals of 5 nm, and the color of the polarizing element or the polarizing plate is calculated by JIS Z 8729 (color representation method L*, a*). The b* indicates the color system indicated by the system and the L*, u*, and v* color systems. The a* and b* of the hue are measured by a spectrophotometer U-4100, and the measured value is used. The hue of the orthogonal bits herein means the hue of the color developed when the two polarizing plates are overlapped in such a manner that the absorption axes are orthogonal to each other, and the hue of the parallel bits means that the absorption axes are orthogonal to each other. The hue of the color developed when the two polarizing plates were superposed. In the L*, a*, b* color system, the closer a* and b* are to zero, the more the hue shows the neutral color. Generally, if the a* value is positive, it means red, if it is negative, it means green, if b* is positive, it means yellow, and if it is negative, it means blue.

The degree of polarization Py is obtained from the parallel-order transmittance Yp corrected by the visibility and the orthogonal-bit transmittance Yc corrected by the visibility, according to the following equation.

Py={(Yp-Yc)/(Yp+Yc)} ^1/2 ×100

Further, the transmittance at the time of irradiating the absolute polarized light was measured using a spectrophotometer ["U-4100" manufactured by Hitachi, Ltd.). When the transmittance is measured, an iodine-based polarizing plate having a transmittance of 43% and a degree of polarization of 99.99% based on JIS Z 8729 (C light source 2° field of view) is provided on the light-emitting side (SKN manufactured by Polatechno Co., Ltd.) -18043P) As an absolute polarizing plate, absolute polarized light can be incident on the measurement sample. The transmittance of the parallel and orthogonal positions of the polarizing element of the present application when incident absolute polarized light is incident is measured. The protective layer of SKN-18043P is a triacetyl cellulose without ultraviolet absorption ability.

The absorption axis of the polarizing plate of the present invention is parallel to the absorption axis of the absolute polarizing plate, and The absolute parallel transmittance of each wavelength obtained when the absolute polarized light is incident is Ky, and the absorption axis of the polarizing plate of the present invention is orthogonal to the absorption axis of the absolute polarizing plate, and is measured when the absolute polarized light is incident. The absolute orthogonal transmittance of each wavelength obtained was Kz, and Ky and Kz of each wavelength were measured.

The polarizing element of the present invention was produced by using a combination of the azo compound represented by the above formula (1) and the azo compound represented by the above formula (2), and the results are shown in Examples 1 to 4.

Example 1

A polyvinyl alcohol film (VF-PS manufactured by Kuraray Co., Ltd.) having an average degree of polymerization of 2% or more having a degree of saponification of 99% or more was immersed in warm water of 45 ° C for 2 minutes, and the stretching ratio was set to 1.30 times by swelling treatment. The swelled film is synthesized by 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, CI direct red 81 having 0.1 kg of the structure of the formula (1), and WO2012/165223 having the structure of the formula (2). 0.85 parts by weight of the dye shown was immersed in an aqueous solution at 45 ° C for 3 minutes and 30 seconds, and the obtained film was subjected to boric acid (Societa Chimica lardrello spa company) 28.6 g/l at 30 ° C, and iodine (Pure Chemical Company) 0.25 g/l, iodine potassium (manufactured by Junsei Chemical Co., Ltd.), 17.7 g/l, and ammonium iodide (manufactured by Junsei Chemical Co., Ltd.), 1.0 g/l, were immersed in an aqueous solution for 2 minutes to contain iodine or iodide for dyeing. The film obtained by dyeing was stretched to 5.0 times, and the film was stretched for 5 minutes in an aqueous solution containing 50.0 g/l of boric acid at 50 °C. While maintaining the stretched state of the film obtained by the boric acid treatment, it was kept at 30 ° C in an aqueous solution adjusted to 20 g/l of potassium iodide and treated for 20 seconds. The film obtained by the treatment was dried at 70 ° C for 9 minutes to obtain a polarizing element of the present invention.

Example 2

In addition, 0.07 parts by weight of the azo compound described in the synthesis example 1 of Japanese Patent No. 2003-215338 having the structure of the formula (1) is changed to 0.17 parts by weight of the CI direct red 81 described in the first embodiment. 1 A polarizing element was produced in the same manner, and it was set as a measurement sample.

Example 3

In the second embodiment, the dyeing was carried out by changing the time during which the azo compound was contained in the polyvinyl alcohol film from 3 minutes and 30 seconds to 3 minutes and 00 seconds, and containing boric acid (manufactured by Societa Chimica lardrello spa) 28.6. g/l, iodine (manufactured by Pure Chemical Co., Ltd.) 0.25 g/l, potassium iodide (manufactured by Junsei Chemical Co., Ltd.) 17.7 g/l, ammonium iodide (manufactured by Junsei Chemical Co., Ltd.) 1.0 g/l in an aqueous solution at 30 ° C A polarizing element was produced in the same manner as in Example 1 except that the iodine and the iodide were contained in the same manner, and the measurement sample was used.

Example 4

In the second embodiment, the azo compound described in Synthesis Example 1 of Japanese Patent No. 2003-215338 having the structure of the formula (1) is added as the azo compound in which the azo compound is contained in the polyvinyl alcohol film. Example 1 of a weight ratio of a dye represented by the synthesis 2 of WO2012/165223 having the structure of the formula (2), and a Japanese Patent Laid-Open No. Hei 3-12606 having a phenyl J acid on a trisazo structure. A polarizing element was produced in the same manner as in Example 1 except that 0.08 parts by weight of the azo compound described above was used, and a measurement sample was prepared.

Comparative example 1

A measurement sample was prepared in the same manner as in Example 1 except that the iodine-based polarizing element containing no dichroic dye was produced in the formulation of Comparative Example 1 of JP-A-2008-065222.

Comparative example 2

A polarizing element was produced in the same manner as in Example 1 except that a polarizing element having only a dichroic dye was produced by the method of Example 1 of JP-A-H11-218611, and a measurement sample was prepared.

Comparative example 3

A polarizing element was produced in the same manner as in Example 1 except that a dye-based polarizing element having only a dichroic dye was produced by the method of Example 3 of Japanese Patent No. 4162334, and a measurement sample was prepared.

Comparative example 4

A polarizing element was produced in the same manner as in Example 1 except that a dye-based polarizing element having only a dichroic dye was produced by the method of Example 1 of Japanese Patent No. 4360100, and a measurement sample was prepared.

The measurement results of Ys, ρ, a* -s, b* -s, a* -p, b* -p, a* -c, b* -c of Examples 1 to 4 and Comparative Examples 1 to 4 are shown. In Table 1.

Table 2 shows the average transmittance of 400 nm to 460 nm, the average transmittance of 550 nm to 600 nm, the average transmittance of 600 nm to 670 nm, and 400 nm to the absolute polarized light of Examples 1 to 4 and Comparative Examples 1 to 4. The absolute value of the difference between the average transmittance of 460 nm and the average transmittance of 550 nm to 600 nm, the average transmittance of 550 nm to 600 nm, and the absolute value of the average transmittance of 600 nm to 670 nm.

In addition, a triacetyl cellulose film (TD-80U manufactured by Fujifilm Co., Ltd.) which is subjected to alkali treatment for the polarizing element obtained by drying is a transparent protective layer, and laminated with a polyvinyl alcohol-based adhesive, even if polarized light is used. The optical characteristics of the plate and the polarizing element are also unchanged. Accordingly, it is understood that the polarizing plate obtained by using the polarizing element has the same performance.

Next, the polarizing element of the present invention was produced by using a combination of the azo compound represented by the above formula (1) and the azo compound represented by the above formula (3), and the results are shown in Examples 5 to 9.

Example 5

A polyvinyl alcohol film (VF-PS manufactured by Kuraray Co., Ltd.) having an average degree of polymerization of 2,400 or more having a degree of saponification of 99% or more was immersed in warm water of 45 ° C for 2 minutes, and the stretching ratio was set to 1.30 times by swelling treatment. The swelled film is 1500 parts by weight of water, 1.5 parts by weight of sodium tripolyphosphate, and has a structure of formula (1): direct red 81 0.1 parts by weight, and the structure of the formula (3) is Japanese Patent Special 2 0.135 parts by weight of the dye shown in Example 3 of No. -61988 was immersed in an aqueous solution adjusted to 45 ° C for 3 minutes and 30 seconds, and the obtained film was contained at 30 ° C in a boric acid (manufactured by Societa Chimica lardrello spa) 28.6 g / l, iodine (manufactured by Pure Chemical Co., Ltd.) 0.25 g / l, potassium iodide (manufactured by Pure Chemical Co., Ltd.) 17.7 g / l, ammonium iodide (manufactured by Pure Chemical Co., Ltd.) 1.0 g / l aqueous solution immersed for 2 minutes, so that it contains iodine Dyeing with iodide. The film obtained by dyeing was stretched to 5.0 times, and the film was stretched for 5 minutes in an aqueous solution containing 50.0 g/l of boric acid at 50 °C. While maintaining the stretched state of the film obtained by the boric acid treatment, it was kept at 30 ° C in an aqueous solution adjusted to 20 g/l of potassium iodide and treated for 20 seconds. The film obtained by the treatment was dried at 70 ° C for 9 minutes to obtain a polarizing element of the present invention. A triacetyl cellulose film (TD-80U manufactured by Fujifilm Co., Ltd.) which was subjected to alkali treatment to the polarizing element obtained by drying was laminated with a polyvinyl alcohol-based adhesive to obtain a polarizing plate. The obtained polarizing plate was cut into 40 mm × 40 mm, and bonded to a glass plate of 1 mm via an adhesive PTR-3000 (manufactured by Nippon Kayaku Co., Ltd.) to prepare a measurement sample.

Example 6

In the same manner, polarized light was produced in the same manner except that 0.07 parts by weight of the azo compound described in Synthesis Example 1 of Japanese Patent No. 2003-215338 having the structure of the formula (1) was changed. The element and the polarizing plate were set as measurement samples.

Example 7

In Example 6, the time during which the azo compound was contained in the polyvinyl alcohol film was changed from 3 minutes and 30 seconds to 3 minutes and 00 seconds, and the boric acid (Societa Chimica lardrello spa company) 28.6 g/l, iodine (pure 0.25 g/l, iodine potassium (manufactured by Pure Chemical Co., Ltd.) 17.7 g/l, and ammonium iodide (manufactured by Junsei Chemical Co., Ltd.) 1.0 g/l in an aqueous solution at 30 ° C for 1 minute and 30 seconds to contain A polarizing element and a polarizing plate were produced in the same manner except that the iodine and the iodide were dyed, and a measurement sample was prepared.

Example 8

In the example 6, the azo compound described in Synthesis Example 1 of Japanese Patent No. 2003-215338 having the structure of the formula (1) is added as the azo compound in the case where the azo compound is contained in the polyvinyl alcohol film. The azo compound described in Example 1 of the Japanese Patent Application Laid-Open No. Hei 2-61988, and the azo compound described in Example 1 of the Japanese Patent Laid-Open Publication No. Hei. A polarizing element and a polarizing plate were produced in the same manner as the measurement sample, except that 0.08 parts by weight was used.

Example 9

The 0.135 parts by weight of the dye shown in Example 3 of the Japanese Patent Publication No. Hei 2-61988 having the structure of the formula (3) used in the embodiment 6 is changed to the Japanese Patent Special Publication No. 60 having the structure of the formula (3). A polarizing element and a polarizing plate were prepared in the same manner as in the above, except that 0.155 parts by weight of the azo compound described in Example 24 was used.

Comparative Example 5~8

Using the polarizing element produced in the above Comparative Examples 1 to 4, a polarizing plate was produced in the same manner as in Example 5, and a measurement sample was prepared.

Ys, ρ, a*-s, b*-s, a*-p, b*-p of Examples 5 to 9 and Comparative Examples 5 to 8 The measurement results of a*-c and b*-c are shown in Table 3.

Table 4 shows the average transmittance of 400 nm to 460 nm, the average transmittance of 550 nm to 600 nm, the average transmittance of 600 nm to 670 nm, and 400 nm to the absolute polarized light of Examples 5 to 9 and Comparative Examples 5 to 8. The absolute value of the difference between the average transmittance of 460 nm and the average transmittance of 550 nm to 600 nm, the average transmittance of 550 nm to 600 nm, and the absolute value of the average transmittance of 600 nm to 670 nm.

According to Examples 1 to 4 and Comparative Examples 1 to 4 shown in Table 1, Examples 5 to 9 and Comparative Examples 5 to 8 shown in Table 3, Ys, ρ, a* - s, b* - s, a * As a result of measuring the results of -p, b*-p, a*-c, b*-c, the polarizing plate of the present invention is obtained by the provision of JIS Z 8729. In the value and the b* value, the a* value and the b* value when the individual transmittance is measured are 1 or less in absolute value, and the two substrates are measured in parallel with respect to the absorption axis direction and are obtained. * The value and the b* value are within 2 in absolute value, and the a* value and the b* value obtained by orthogonally measuring the two substrates with respect to the absorption axis direction are characterized by an absolute value of 2 or less. The polarizing element having a single body transmittance of 35% to 45% or a polarizing plate exhibits achromatic white and black in the case of the white display of the parallel position and the black display of the orthogonal position. With respect to the average transmittance of 410 nm to 750 nm, it is understood that the polarizing element and the polarizing plate of the present invention have a polarizing plate of about 31 to 32% as described in the first or second embodiment of Japanese Patent No. 3357803 (Patent Document 2) of the prior art. High transmittance. Further, if the average transmittance exceeds 40%, the L value (L*) also exceeds 70, and thus a very good polarizing element is obtained. It is said that by making the hue of the color medium within ±1.0 and L* exceeding 65, white paper of good quality can be realized, but by making L* 70, it is possible to realize paper of high quality. White, the so-called ultra-white polarizing plate.

Further, as shown in Tables 2 and 4, when the transmittances of the respective wavelengths were compared, it was found that the polarizing element and the polarizing plate of Examples 1 to 9 irradiated the absolute polarization light to the absorption axis direction of the substrate polarizing element. The transmittance of each wavelength when the vibration direction is the polarized light in the orthogonal direction, the difference between the average transmittance of 550 nm to 600 nm and the average transmittance of 400 nm to 460 nm is adjusted to be within 4%, and the average transmittance of 600 to 670 nm is obtained. The difference between the average transmittance of 550 to 600 nm is adjusted to 3% or less, and the transmittance at the wavelength of the polarized light in which the direction of the absolute polarized light is radiated in the direction of the absorption axis of the substrate polarizing element is 550 nm. The difference between the average transmittance of 600 nm and the average transmittance of 400 nm to 460 nm is adjusted to be within 1%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is adjusted to be within 1%. The polarizing plate obtained by using the above polarizing element has a high transmittance, and can exhibit achromatic white when the absorption axis of the polarizing element is disposed in parallel, and can be expressed when the absorption axis of the polarizing element is orthogonally disposed. Achromatic black. Therefore, the polarizing element or the polarizing plate of the present invention is used. The crystal display device is not only a high-brightness, high-contrast, but also high-reliability liquid crystal display device having high contrast and high color reproducibility for a long period of time.

Claims (6)

A polarizing element comprising a substrate containing iodine and an azo compound, wherein the azo compound is a) an azo compound represented by the formula (1) and an azo represented by the formula (2) a combination of compounds, or b) a combination of an azo compound represented by the formula (1) and an azo compound represented by the formula (3), a salt thereof, or a transition metal complex thereof, in accordance with JIS Z In the a* value and the b* value obtained by 8729, the a* value and the b* value when the transmittance of the individual body are measured are 1 or less in absolute value, so that the two substrates are parallel to the absorption axis direction. The a* value and the b* value obtained by the measurement are in an absolute value of 2 or less, and the a* value and the b* value obtained by orthogonally measuring the two substrates with respect to the absorption axis direction are absolute values. Calculated as less than 2, the individual body transmittance is 35% to 45%. (A ₁ represents a phenyl group having a substituent or a naphthyl group, and R ₁ or R ₂ each independently represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group, X ₁ represents an amine group which may have a substituent, a benzylamino group which may have a substituent, an aminobenzamide group which may have a substituent, a phenylamine group which may have a substituent, and a benzene which may have a substituent Alkylazo)[Chemical 2] (wherein A ₂ and A ₃ each independently represent a phenyl group having a substituent or a naphthyl group, and at least one of the substituents is a hydrogen atom, a sulfo group, a lower alkyl group, a lower alkoxy group, and a sulfo group; a lower alkoxy group, a carboxyl group, a nitro group, an amine group, or a substituted amine group, and R ₃ and R ₄ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group. base) (wherein A ₄ represents a nitro group or an amine group, R ₉ represents a hydrogen atom, a hydroxyl group, a lower alkyl group, a lower alkoxy group, a sulfo group, or a lower alkoxy group having a sulfo group, and X ₂ represents a substituent group; An amine group, a phenylamine group which may have a substituent). The polarizing element of claim 1 has a degree of polarization of 99% or more. The polarizing element according to claim 1 or 2, wherein the transmittance of each wavelength when the direction of the vibration of the absolute polarization light is irradiated to the direction of the absorption axis of the polarizing element is the polarization direction of the orthogonal direction, the average transmittance of 550 nm to 600 nm and 400 nm The difference between the average transmittances to 460 nm is within 4%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is within 3%, and further, the absolute polarization of the absorption axis direction of the polarizing element is irradiated. The transmittance of each wavelength when the vibration direction is the polarized light in the parallel direction, 550 nm to 600 The difference between the average transmittance of nm and the average transmittance of 400 nm to 460 nm is within 1%, and the difference between the average transmittance of 600 to 670 nm and the average transmittance of 550 to 600 nm is within 1%. The polarizing element according to any one of claims 1 to 3, wherein the substrate comprises a polyvinyl alcohol-based resin film. A polarizing plate obtained by providing a transparent protective layer on at least one side of a polarizing element according to any one of claims 1 to 4. A liquid crystal display device using the polarizing element of any one of claims 1 to 4 or the polarizing plate of claim 5.