JP7448477B2 - Polarizing elements, polarizing plates and optical members using the same, etc. - Google Patents

Description

The present invention relates to a dye-based polarizing element, a polarizing plate, an optical member, etc. using the same.

Polarizing elements are generally manufactured by adsorbing and orienting iodine, which is a dichroic dye, or a dichroic dye onto a base film such as polyvinyl alcohol resin. A polarizing plate is manufactured by laminating a protective film made of triacetyl cellulose or the like to at least one side of this polarizing element via an adhesive layer. Polarizing plates are used in liquid crystal display devices and the like. A polarizing plate using iodine as a dichroic dye is called an iodine-based polarizing plate, while a polarizing plate using a dichroic dye as a dichroic dye is called a dye-based polarizing plate. Among these, dye-based polarizing plates have high heat resistance, high humidity and heat durability, and high stability, and are also characterized by high color selectivity due to the combination of dichroic dyes.
Further, Patent Documents 1 to 4 and Non-Patent Documents 1 and 2 disclose dye-based polarizing elements containing an azo compound.

Japanese Patent Application Publication No. 11-218611 Japanese Patent Application Publication No. 2001-033627 Japanese Patent Application Publication No. 2004-251962 Japanese Patent Application Publication No. 2004-075719 Japanese Patent Application Publication No. 08-291259 Japanese Patent Application Publication No. 2002-275381

Yutaka Hosoda, “Dye Chemistry”, Gihodo Publishing Co., Ltd., 1957, pp. 621-626 Supervised by Masahiro Irie, "Applications of Functional Pigments" (1st edition), CMC Publishing Co., Ltd., June 2002, p. 98-104

An object of the present invention is to provide a polarizing element, a polarizing plate, an optical member, etc. (hereinafter also referred to as a "polarizing element, etc.") having optical properties (polarizing performance, contrast, etc.) that are equivalent to or better than conventional ones. It is in.

As a result of intensive studies to solve the above problems, the present inventors discovered that the optical properties of a polarizing element can be improved by combining two types of azo compounds having a specific structure, and the present invention I was able to complete it.

That is, the present invention relates to Inventions 1 to 7 below, but is not limited thereto.
[Invention 1]
A polarizing element comprising an azo compound represented by formula (1) or a salt thereof, an azo compound represented by formula (2) or a salt thereof, and a base material:

(In formula (1), Ar ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent, and Rr ₁ to Rr ₄ each independently represent a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxyl group. or represents a C1-4 alkoxyl group having a sulfo group, Xr ₁ is an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, represents a benzoyl group which may have a substituent, a benzoylamino group which may have a substituent, or a naphthotriazole group which may have a substituent; m represents 0 or 1);

(In formula (2), Ab ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent, and Rb ₁ to Rb ₅ each independently represent a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxyl group. or a C1-4 alkoxyl group having a sulfo group, where Xb ₁ is an amino group which may have a substituent, a phenylamino group which may have a substituent, or a phenylazo group which may have a substituent. , represents a benzoyl group which may have a substituent, a benzoylamino group which may have a substituent, or a naphthotriazole group which may have a substituent).
[Invention 2]
The azo compound represented by formula (2) is represented by formula (3)

(In formula (3), Ab ₁ , Rb ₁ to Rb ₅ and Xb ₁ are the same as those described in formula (2) above)
The polarizing element according to invention 1, which is an azo compound represented by:
[Invention 3]
The polarizing element according to invention 1 or 2, wherein Rb ₅ is a methoxy group.
[Invention 4]
Formula (4)

(In formula (4), Ay ₁ represents a sulfo group, a carboxyl group, a hydroxyl group, a C1-4 alkyl group, or a C1-4 alkoxyl group, and Ry ₁ to Ry ₄ each independently represent a hydrogen atom, a C1-4 alkyl group, and a C1-4 alkyl group. group or C1-4 alkoxyl group, p represents 1, 2, or 3)
The polarizing element according to any one of Inventions 1 to 3, further comprising an azo compound represented by:
[Invention 5]
The polarizing element according to any one of inventions 1 to 4, wherein the base material is a film containing a polyvinyl alcohol resin.
[Invention 6]
A polarizing plate comprising the polarizing element according to any one of inventions 1 to 5 and a transparent protective layer provided on one or both sides of the polarizing element.
[Invention 7]
An optical member, device, or device comprising the polarizing element according to any one of inventions 1 to 5 or the polarizing plate according to invention 6.

According to the present invention, a polarizing element and the like having excellent optical properties can be provided. In one aspect, the polarizing element and the like of the present invention have excellent durability (humidity resistance, heat resistance, etc.). In one embodiment, the polarizing element and the like of the present invention have good polarization performance and contrast, and can meet recent demands for high-definition displays. In one embodiment, the polarizing element and the like of the present invention have high transmittance and little change in polarization degree under high temperature and/or high humidity environments, which are recently required for touch panels, organic EL displays, and the like.

In the present specification, the term "azo compound" may include a free form of an azo compound, a salt of an azo compound, a mixture of a free form (free acid or free base) and a salt, and the like. Furthermore, in the present specification, the term "substituent" includes a hydrogen atom for convenience.

<Polarizing element>
The polarizing element of the present invention includes a base material, an azo compound represented by the above formula (1), and an azo compound represented by the above formula (2). When the azo compound represented by the above formula (1) is an azo compound represented by the above formula (3), a polarizing element having a higher degree of polarization can be realized. It is more preferable that the polarizing element of the present invention contains an azo compound represented by the above formula (4) in addition to the azo compound represented by the above formula (1) and formula (2), respectively. Thereby, a polarizing element having an even higher degree of polarization can be realized. That is, it is particularly preferable that the base material contains an azo compound represented by each of the above formulas (1), (2), and (4). When the azo compound used in the present invention has a functional group such as a hydroxyl group, a carboxyl group, or a sulfo group, it may be used as a free acid, a salt, or a mixture of a free acid and a salt . It's okay.

Examples of the salts of the azo compounds include alkali metal salts such as lithium salts, sodium salts, and potassium salts; alkaline earth metal salts such as calcium salts; ammonium salts; and organic salts such as alkylamine salts and alkanolamine salts. It is preferably a lithium salt, a sodium salt, a potassium salt, or an ammonium salt, more preferably a lithium salt or a sodium salt, and even more preferably a sodium salt.

The azo compound described above can generally be synthesized by performing known diazotization and coupling according to azo compound synthesis methods known in the art (for example, page 626 of Non-Patent Document 1). . A polarizing element can be produced by dissolving an azo compound in a solution and impregnating it into a base material in a dyeing process.

The azo compound represented by the above formula (1) will be explained.

In the above formula (1), Ar ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent.

When Ar ₁ is a phenyl group having a substituent, the substituent is a sulfo group, a carboxyl group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a sulfo group, a nitro group, a benzoyl group, It preferably has at least one of an amino group, an acetylamino group, and a C1-4 alkylamino group-substituted amino group, and more preferably at least one sulfo group or carboxyl group. When the phenyl group has two or more substituents, at least one of the substituents is a sulfo group or a carboxyl group, and other substituents include a sulfo group, a carboxyl group, a C1-4 alkyl group, and a C1-4 alkyl group. Preferred are alkoxyl groups, C1-4 alkoxyl groups having a sulfo group, nitro groups, benzoyl groups, amino groups, acetylamino groups, and C1-4 alkylamino group-substituted amino groups, and more preferred are sulfo groups, methyl groups, and ethyl groups. , methoxy group, ethoxy group, carboxyl group, nitro group, benzoyl group, and amino group, and particularly preferably sulfo group, methyl group, methoxy group, ethoxy group, benzoyl group, and carboxyl group. The C1-4 alkoxyl group having a sulfo group is preferably a straight-chain alkoxyl group , and the sulfo group is preferably substituted at the terminal end of the alkoxyl group, more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, particularly Preferably it is a 3-sulfopropoxy group. The number of sulfo groups in the phenyl group having the above substituents is preferably 1 or 2, and there is no particular limitation on the substitution position, but if the bonding position with the CONH moiety in formula (1) is set as the 1st position, the 4th position Only, the combination of 2nd and 4th place, and the combination of 3rd and 5th place are preferable.

In the above formula (1), when Ar ₁ is a naphthyl group having a substituent, the naphthyl group may be bonded to the CONH site at the 1st position or may be bonded to the CONH site at the 2nd position. Preferably, the naphthyl group is attached to the CONH moiety at its 2-position. The naphthyl group preferably has at least one of a sulfo group, a hydroxyl group, a carboxyl group, and a C1-4 alkoxy group having a sulfo group as a substituent, and more preferably has at least one sulfo group or a carboxy group. When having two or more substituents, preferably at least one of the substituents is a sulfo group and the other substituents are selected from a sulfo group, a hydroxyl group, a carboxyl group, and a C1-4 alkoxyl group having a sulfo group. . As the C1-4 alkoxyl group having a sulfo group, a straight chain alkoxyl group is preferable, and the substitution position of the sulfo group is preferably at the alkoxyl group terminal, more preferably a 3-sulfopropoxy group and a 4-sulfobutoxy group, and particularly preferable. is a 3-sulfopropoxy group. When the naphthyl group having the above substituents has 2 sulfo groups as substituents, the positions of the sulfo groups on the naphthyl group are 4 and 8 positions, assuming that the bonding position with the CONH site is the 2 position. The combination and the combination of the 6th and 8th positions are preferred, and the combination of the 6th and 8th positions is more preferred. When the number of sulfo groups in the naphthyl group is 3, and when the bonding position with the CONH moiety in formula (1) is set as the 2-position, the combination of the 3-position, 6-position, and 8-position is preferable as the substitution position of the sulfo group. Particularly preferred.

In the above formula (1), Rr ₁ to Rr ₄ each independently represent a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, or a C1-4 alkoxyl group having a sulfo group. Rr ₁ to Rr ₄ are each independently preferably a hydrogen atom, a C1-4 alkyl group, or a C1-4 alkoxyl group, more preferably a hydrogen atom, a methyl group, or a methoxy group. The C1-4 alkoxyl group having a sulfo group is preferably a straight-chain alkoxyl group, and the sulfo group is preferably substituted at the terminal end of the alkoxyl group, more preferably a 3-sulfopropoxy group or a 4-sulfobutoxy group, particularly Preferably it is a 3-sulfopropoxy group.

In the above formula (1), m represents 0 or 1. When m is 0, it is easy to produce a polarizing plate with little wavelength dependence, that is, a polarizing element or polarizing plate having a neutral gray color, and when m is 1, a high degree of polarization is exhibited, so these are preferred forms. one of.

In the above formula (1), Xr ₁ represents an amino group that may have a substituent, a phenylamino group that may have a substituent, a phenylazo group that may have a substituent, or a phenylazo group that may have a substituent. represents a benzoyl group which may have a substituent, a benzoylamino group which may have a substituent, or a naphthotriazole group which may have a substituent, preferably a phenylamino group which may have a substituent.

When Xr ₁ is a naphthotriazole group which may have a substituent, the naphthotriazole is 1,2-naphthotriazole or 2,3-naphthotriazole, preferably 2,3-naphthotriazole. The bonding position between Xr ₁ and the naphthyl group is not particularly limited, but is preferably the 2-position (center nitrogen atom) of the triazole ring.

The above amino group which may have a substituent is preferably a hydrogen atom, a hydroxy group, a carboxy group, a C1-4 alkyl group which may have a sulfo group, and a C1-4 alkyl group which may have a sulfo group. An amino group that may have one or two substituents selected from the group consisting of 4 alkoxyl groups, more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, and an ethoxy group. It is an amino group which may have one or two selected substituents. The above phenylamino group which may have a substituent is preferably a group consisting of a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, a sulfo group, an amino group, a hydroxyl group, and a C1-4 alkylamino group. A phenylamino group which may have one or two substituents selected from, more preferably one selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group, a sulfo group, and an amino group. It is a phenylamino group which may have one or two substituents. The above-mentioned phenylazo group which may have a substituent is preferably one to one selected from the group consisting of a hydrogen atom, a hydroxy group, a C1-4 alkyl group, a C1-4 alkoxy group, an amino group, and a carboxyethylamino group. It is a phenylazo group having three. The benzoyl group which may have a substituent is preferably a benzoyl group having one selected from the group consisting of a hydrogen atom, a hydroxyl group, a sulfo group, an amino group, and a carboxyethylamino group. The benzoylamino group which may have a substituent is preferably a benzoylamino group having one selected from the group consisting of a hydrogen atom, a hydroxyl group, an amino group, and a carboxyethylamino group. The naphthotriazole group which may have a substituent preferably consists of a hydrogen atom, a hydroxy group, a carboxy group, a C1-4 alkyl group, a C1-4 alkoxy group, a sulfo group, an amino group, and a carboxyethylamino group. A naphthotriazole group having 1 to 3 sulfo groups selected from the group, more preferably a naphthotriazole group having 1 to 3 sulfo groups. Xr ₁ is preferably a benzoylamino group which may have a substituent or a phenylamino group which may have a substituent, more preferably a phenylamino group which may have a substituent. . A phenylamino group which may have a substituent, a phenylazo group which may have a substituent, a benzoyl group which may have a substituent, or a substituent in a benzoylamino group which may have a substituent The position is not particularly limited, but if there is one substituent, it may be substituted at the p-position relative to the bonding position of the amino group, azo group, carbonyl group, or amide group bonded to the naphthalene ring in formula (1) above. is particularly preferred. The substitution position in the naphthotriazole group which may have a substituent is not particularly limited, but when there is one substituent, the ring condensed position with the triazole ring is "1-position and 2-position" or "2-position and 3-position". ”, the 4th or 6th position of the naphthalene ring part is preferable, and when there are two substituents, the combination of the 5th and 7th positions, or the 6th and 8th positions is preferable (see the figure below). ).

Methods for obtaining the azo compound represented by the above formula (1) include, but are not limited to, methods described in Patent Document 5, Patent Document 6, and the like.

Further specific examples of the azo compound represented by the above formula (1) are shown below.

The azo compound represented by the above formula (2) will be explained.

In the above formula (2), Ab ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent.

When Ab ₁ is a phenyl group having a substituent, the phenyl group has a sulfo group, a carboxyl group, a C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy group having a sulfo group, a nitro group. , a benzoyl group, an amino group, an acetylamino group, and a C1-4 alkylamino group-substituted amino group, and more preferably at least one sulfo group or carboxyl group. When the phenyl group has two or more substituents, at least one of those substituents is a sulfo group or a carboxyl group, and the other substituents are a sulfo group, a carboxyl group, a C1-4 alkyl group, a C1-4 alkoxyl group. , a C1-4 alkoxyl group, a nitro group, a hydroxyl group, an amino group or a substituted amino group (especially an acetylamino group or a C1-4 alkylamino group) having a sulfo group, a sulfo group, a carboxyl group, a methyl A sulfo group, a carboxyl group, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a nitro group or an amino group are more preferable. More preferably, it is a sulfo group, a carboxyl group, a methyl group, a methoxy group, or an ethoxy group. Further, it is also preferable that the other substituents are a sulfo group, a C1-4 alkyl group, or a C1-4 alkoxyl group. Furthermore, the C1-4 alkoxyl group having a sulfo group is preferably a straight-chain alkoxyl group, and the substitution position of the sulfo group is preferably at the terminal of the alkoxyl group. As the C1-4 alkoxyl group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. The number of substituents on the phenyl group having the above-mentioned substituents is preferably 1 or 2, and more preferably 2. The position of the substituent on the phenyl group is not particularly limited, but may be only the 4-position, a combination of the 2-position and the 4-position, or the 3-position and the 5-position with respect to the azo bond position in the above formula (2). A combination of these is preferred, and a combination of the 2nd and 4th positions is particularly preferred.

In the above formula (2), when Ab ₁ is a naphthyl group having a substituent, it is preferable that the naphthyl group has at least one sulfo group as a substituent, and when the naphthyl group has two or more substituents It is preferable that at least one of these substituents is a sulfo group, and the other substituents are a sulfo group, a hydroxyl group, a carboxyl group, or a C1-4 alkoxyl group having a sulfo group. Furthermore, the C1-4 alkoxyl group having a sulfo group is preferably a straight-chain alkoxyl group, and the substitution position of the sulfo group is preferably at the terminal of the alkoxyl group. As the C1-4 alkoxyl group having a sulfo group, a 3-sulfopropoxy group or a 4-sulfobutoxy group is more preferable, and a 3-sulfopropoxy group is particularly preferable. When the number of substitutions of the sulfo group on the naphthyl group having the above-mentioned substituent is 2, the substitution position of the sulfo group is between the 4-position and the 8-position, assuming that the azo bond position in the above formula (2) is the 2-position. A combination or a combination of the 6th and 8th positions is preferred, and a combination of the 6th and 8th positions is particularly preferred. When the number of sulfo groups on the naphthyl group is 3, the substitution positions of the sulfo groups are particularly preferably a combination of the 1st, 3rd and 6th positions.

In the above formula (2), Xb ₁ is an amino group that may have a substituent, a phenylamino group that may have a substituent, a phenylazo group that may have a substituent, or a phenylazo group that may have a substituent. represents a benzoyl group that may have a substituent, a benzoylamino group that may have a substituent, or a naphthotriazole group that may have a substituent; A phenylamino group which may have a substituent, a phenylazo group which may have a substituent, or a naphthotriazole group which may have a substituent are preferable. A phenylamino group which may have a substituent or a phenylazo group which may have a substituent is more preferable, and a phenylamino group which may have a substituent is particularly preferable.

The above amino group preferably has 1 to 2 substituents. The substituent is preferably a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group, or a C1-4 alkylamino group.

The phenylamino group preferably has one to two substituents. The substituent is preferably a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group, or a substituted amino group, and a hydrogen atom, a methyl group, a methoxy group, or a sulfo group. , an amino group, or a substituted amino group are more preferred, a hydrogen atom, a methyl group, a methoxy group, a sulfo group, an amino group, or a C1-4 alkylamino group are even more preferred, and a hydrogen atom, a methoxy group, or an amino group is particularly preferred. .

The phenylazo group preferably has 1 to 3 substituents. The substituent is preferably a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group, or a substituted amino group; A 4-alkyl group, a C1-4 alkoxyl group, an amino group, or a carboxyethylamino group is more preferable, and a hydrogen atom, a hydroxyl group, an amino group, a methyl group, a methoxy group, or a carboxyl group is even more preferable, and a hydroxyl group is Particularly preferred.

The benzoyl group preferably has one substituent. The substituent is preferably a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group, or a substituted amino group, and a hydrogen atom, an amino group, a substituted amino group, or A hydroxyl group is more preferred, a hydrogen atom, an amino group, or a carboxyethylamino group is even more preferred, and an amino group is particularly preferred.

The benzoylamino group preferably has one substituent. The substituent is preferably a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, a hydroxyl group, a carboxyl group, a sulfo group, an amino group, or a substituted amino group, and a hydrogen atom, an amino group, a substituted amino group, or A hydroxyl group is more preferred, a hydrogen atom, an amino group, or a carboxyethylamino group is even more preferred, and an amino group is particularly preferred.

When Xb ₁ is a naphthotriazole group which may have a substituent, the naphthotriazole is 1,2-naphthotriazole or 2,3-naphthotriazole, preferably 2,3-naphthotriazole. Although the bonding position between Xb ₁ and the naphthyl group is not particularly limited, the 2-position (center nitrogen atom) of the triazole ring part is preferable. The naphthotriazole group preferably has 1 to 3 substituents, more preferably 2 substituents. The substituent is preferably a hydrogen atom, a hydroxy group, a carboxy group, a C1-4 alkyl group, a C1-4 alkoxy group, a sulfo group, an amino group, or a carboxyethylamino group, and more preferably a sulfo group.

When the above Xb ₁ is a phenylamino group having a substituent, a phenylazo group having a substituent, a benzoyl group having a substituent, or a benzoylamino group having a substituent, and there is one substituent, the substituent Although the position of is not particularly limited, it is preferably p-position with respect to the phenylamino group, the phenylazo group, the benzoyl group, or the amino group, azo group, carbonyl group, or amide group of the benzoylamino group. When the above Xb ₁ is a naphthotriazole group having a substituent, the substitution position is not particularly limited, but when there is one substituent, the ring condensed position with the triazole ring is set to "1-position and 2-position" or "2-position and The 4th or 6th position of the naphthalene ring moiety is preferably numbered as 3rd position, and when there are two substituents, a combination of 5th and 7th positions or a combination of 6th and 8th positions is preferred.

In the above formula (2), Rb ₁ to Rb ₅ each independently represent a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, or a C1-4 alkoxyl group having a sulfo group; It is preferably an alkyl group or a C1-4 alkoxyl group, and more preferably a hydrogen atom, a methyl group or a methoxy group. The C1-4 alkoxyl group having a sulfo group is preferably a straight-chain alkoxyl group, and the sulfo group is preferably substituted at the terminal of the alkoxyl group. Preferred examples of the C1-4 alkoxy group having a sulfo group include a 3-sulfopropoxy group or a 4-sulfobutoxy group, with a 3-sulfopropoxy group being particularly preferred. Further, when Rb ₅ is a methoxy group, the polarization performance of the polarizing element is particularly improved, so it is particularly preferable.

When the azo compound represented by the above formula (2) is an azo compound represented by the above formula (3), the polarization performance of the polarizing element is further improved. In the above formula (3), Ab ₁ , Rb ₁ to Rb ₅ and Xb ₁ are the same as those described in the above formula (2).

In order to further improve the optical properties of the polarizing element, the above formula (2) is preferably an azo compound represented by the following formula (5).

In the above formula (5), Ab ₁ , Rb ₂ , Rb ₄ and Xb ₁ are each the same as described in the above formula (2).

In the above formula (5), Rb ₂ and Rb ₄ each independently represent a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxyl group, or a C1-4 alkoxyl group having a sulfo group; Alternatively, it is preferably a methoxy group, and more preferably a hydrogen atom or a methyl group. When the azo compound represented by the above formula (2) has a structure as represented by the above formula (5), it is preferable because it is possible to particularly improve polarization properties.

The azo compounds represented by the above formulas (2), (3), and (5) can be synthesized using, for example, the synthesis method described in Non-Patent Document 1, International Publication No. 2012/108169, International Publication No. It can be synthesized by performing diazotization and coupling as described in No. 2012/108173 and the like. The method for synthesizing the azo compounds represented by the above formulas (2), (3), and (5) is not limited to the methods described in the above documents. Further, the azo compounds represented by the above formulas (2), (3) and (5) can also be treated with copper sulfate or the like to form copper complex salt compounds.

Specific examples of the azo compound represented by the above formula (2) are listed below. In addition, in the following compound examples, the sulfo group and the hydroxyl group are expressed in the form of a free acid, but they may be in the form of a salt.

In the above polarizing element, the content of the azo compound represented by the above formula (2) is within the range of 10 to 5000 parts by weight based on 100 parts by weight of the azo compound represented by the above formula (1). is preferred, and more preferably within the range of 20 to 3,000 parts by weight.

The polarizing element can further include an azo compound represented by the above formula (4).

Examples of methods for synthesizing the azo compound represented by the above formula (4) include the synthesis method described in Non-Patent Document 1 and the method described in International Publication No. 2007/138980; It is not limited.

Examples of the azo compound represented by the above formula (4) include C.I. I. Direct Yellow 12, C. I. Direct Yellow 72, C. I. Direct Orange 39 (CAS number: 1325-54-8), azo compounds described in International Publication No. 2007/138980, and the like may be mentioned, but are not limited thereto.

Specific examples of the azo compound represented by the above formula (4) are listed below. In addition, in the following compound examples, the sulfo group and the carboxyl group are expressed in the form of a free acid, but the sulfo group and the carboxyl group may be in the form of a salt.

In the above polarizing element, the content of the azo compound represented by the above formula (4) is within the range of 1 to 1000 parts by weight based on 100 parts by weight of the azo compound represented by the above formula (1). is preferable, and more preferably within the range of 5 to 800 parts by weight.

In the above polarizing element, depending on color adjustment etc., other organic dyes (especially azo compounds) other than the azo compounds represented by the above formulas (1), (2) and (4), such as non-patent literature One or more azo compounds such as those described in 2 are used in combination with azo compounds represented by the above formulas (1) and (2), respectively, or with the above formulas (1), (2), and (4). It may be used in combination with the azo compounds represented respectively. The other organic dyes mentioned above to be used in combination are not particularly limited, but are dyes that can dye hydrophilic polymers and are different from the absorption wavelength range of the azo compounds represented by the above formulas (1) and (2), respectively. It is preferable that the dye has light absorption in the wavelength range and has high dichroism. Specific examples of other organic dyes include the azo compounds described in Non-Patent Document 2 (for example, C.I. Direct Yellow 28), C.I. I. Direct Red 2, C. I. Direct Red 31, C. I. Direct Red 79, C. I. Direct Red 247, C. I. Direct Green 80, C. I. Direct Green 59, C. I. Direct Blue 202, C. I. Examples include azo compounds such as Direct Violet 9. These azo compounds are used in the form of free acids or in the form of salts such as alkali metal salts (eg, sodium salts, potassium salts, lithium salts), ammonium salts, salts of amines, and the like. If necessary, when using other organic dyes in combination, the intended polarizing element may be a polarizing element with a more neutral color, a polarizing element with a distinctive color, a color polarizing element for liquid crystal projectors, or other color polarizing elements. Depending on which one is used, the type of other organic dyes to be blended can be changed. The blending amount of the above other organic dyes (in the case of two or more types, their total blending amount) is not particularly limited, but generally, the above formula (1), formula (2) and formula The amount is preferably in the range of 0.1 to 1000 parts by weight based on 100 parts by weight of the total amount of the azo compounds represented by (4).

The base material is preferably a hydrophilic polymer. Examples of hydrophilic polymers include, but are not limited to, polyvinyl alcohol or derivatives thereof, amylose resins, starch resins, cellulose resins, polyacrylate resins, etc. As the base material, polyvinyl alcohol or a derivative thereof (hereinafter referred to as "polyvinyl alcohol resin") is most preferable from the viewpoint of dyeability, resin crosslinkability, etc. The polarizing element can be produced by forming the base material into a film shape, adsorbing the azo compound and other compounds onto the film-shaped base material, and applying an orientation treatment such as stretching.

The method for producing the polyvinyl alcohol resin is not particularly limited, and any known production method can be employed. As a method for producing a polyvinyl alcohol resin, for example, it can be obtained by saponifying a polyvinyl acetate resin (a homopolymer or copolymer of vinyl acetate). Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of other monomers copolymerizable with vinyl acetate. Examples of copolymers of other monomers copolymerizable with vinyl acetate include copolymers of unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The polyvinyl alcohol resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes.

Although the degree of saponification of the above-mentioned polyvinyl alcohol-based resin is not limited, productivity may be significantly reduced due to elution of the polyvinyl alcohol-based resin, in-plane unevenness of optical properties, decrease in dyeability in the dyeing process, or induction of breakage in the stretching process. From the viewpoint of preventing a decrease, it is usually preferably 85% or more, more preferably 95 mol% or more, even more preferably 99 mol% or more, and particularly preferably 99.5 mol% or more.

The degree of polymerization of the above-mentioned polyvinyl alcohol resin is not limited, but from an industrial point of view to prevent productivity from decreasing due to hardening of the polyvinyl alcohol resin or deterioration of film formability and stretchability, it should be 10,000 or less. It is preferable that there be. In order to improve the optical properties of the polarizing element, the degree of polymerization of the polyvinyl alcohol resin is preferably from 1,000 to 10,000, more preferably from 2,000 to 10,000, and even more preferably from 3,500 to 10,000. It is preferably 5,000 to 10,000, particularly preferably 5,000 to 10,000. The degree of polymerization of the polyvinyl alcohol resin indicates the viscosity average degree of polymerization, and can be determined by a method well known in the technical field.

Hereinafter, a specific method for manufacturing a polarizing element will be described using an example in which the base material is a film made of polyvinyl alcohol resin.

First, a film material made of polyvinyl alcohol resin is obtained by forming the polyvinyl alcohol resin into a film. Film forming methods for polyvinyl alcohol resin include melt extrusion of hydrous polyvinyl alcohol resin, casting film forming method, wet film forming method (method in which film is formed by discharging into a poor solvent), and gel film forming method. (a method in which an aqueous solution of polyvinyl alcohol resin is once cooled and turned into a gel, and then the solvent is extracted and removed), a cast film formation method (a method in which an aqueous solution of polyvinyl alcohol resin is poured onto a substrate and dried), and a combination of these methods. Methods such as these can be adopted, but are not limited to these methods.

When a solvent is used during the above film formation, the solvent is not particularly limited, and examples thereof include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, and diethylene glycol. , triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, water and the like. These solvents may be used alone or in combination of two or more. Although the amount of solvent used during film formation is not limited, the viscosity of the film forming stock solution increases, making filtration and defoaming difficult during preparation, making it difficult to obtain a film material free of foreign matter and defects. From the viewpoint of preventing this, the amount is preferably 70% by weight or more based on the entire film forming stock solution (mixture containing a polyvinyl alcohol resin and a solvent used for film forming). In addition, the viscosity of the film-forming stock solution becomes too low, making it difficult to control the desired thickness, increasing the influence of surface fluctuations caused by wind during drying, increasing drying time, and reducing productivity. Therefore, the amount of solvent is preferably 95% by weight or less.

A plasticizer may be used when producing the film material. Examples of the plasticizer include, but are not limited to, glycerin, diglycerin, ethylene glycol, propylene glycol, and low molecular weight polyethylene glycol. The amount of the plasticizer to be used is also not particularly limited, but it is usually preferably within the range of 5 to 15 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin.

Examples of methods for drying the original film after film formation include, but are not limited to, drying with hot air, contact drying using a hot roll, drying using an infrared heater, and the like. Further, one type of these drying methods may be used alone, or two or more types may be used in combination. The drying temperature is also not particularly limited, but is preferably within the range of 50 to 70°C.

It is preferable that the raw film after the above-mentioned drying is subjected to a heat treatment in order to control the degree of swelling within a predetermined range described below. The heat treatment method includes, for example, a method using hot air, a method of bringing the original film into contact with a hot roll, etc., and is not particularly limited as long as the method can be treated with heat. Further, one type of these methods may be used alone, or two or more types may be used in combination. The heat treatment temperature is not particularly limited, but is preferably within the range of 110 to 140°C. The heat treatment time is preferably approximately 1 to 10 minutes, but is not particularly limited.

Although the thickness of the film obtained in the above step is not limited, it is preferably 20 μm or more from the viewpoint of preventing the film from being easily broken. In addition, from the viewpoint of preventing the stress applied to the film during stretching from increasing, the mechanical load during the stretching process increasing, and the need for large-scale equipment to withstand the load, the thickness is preferably 100 μm or less. The thickness is more preferably 20 to 80 μm, and even more preferably 20 to 60 μm.

The raw film made of polyvinyl alcohol resin obtained in the above step is then subjected to a swelling step.

The swelling step is carried out by immersing the raw film made of polyvinyl alcohol resin in a solution at 20 to 50° C. for 30 seconds to 10 minutes. Preferably, the solution is an aqueous solution. Swelling of the film can also occur during dyeing treatment with an azo compound, so when trying to shorten the time required for manufacturing a polarizing element, the swelling step can be omitted.

The degree of swelling F of the above-mentioned raw film is not limited, but from the viewpoint of preventing the degree of elongation during stretching from decreasing significantly, increasing the possibility of breakage, and making it difficult to perform sufficient stretching, the degree of swelling is 180. % or more, more preferably 200% or more. Further, from the viewpoint of preventing significant wrinkles, sagging, and breakage during stretching, it is preferably 260% or less, more preferably 240% or less. It is more preferably 200 to 240%, and even more preferably 210 to 230%. In order to control the degree of swelling F, a suitable degree of swelling F can be selected by, for example, the temperature and time when heat-treating the original film after film formation.

The degree of swelling F of the original film can be measured by a method well known in the technical field, for example, by the following method. First, the original film was cut into 5 cm x 5 cm and immersed in 1 liter of distilled water at 30° C. for 4 hours. The immersed film is taken out of the distilled water and sandwiched between two filter papers to allow the water droplets on the surface of the film to be absorbed by the filter paper, and then the weight [β(g)] of the immersed film is measured. Furthermore, the film that has been immersed and has absorbed water droplets is dried in a dryer at 105° C. for 20 hours, cooled in a desiccator for 30 minutes, and then the weight [γ (g)] of the film after drying is measured. Then, the degree of swelling F of the film material is calculated using the following formula (v).

Swelling degree F = 100 x β/γ (%) ... (v)

After the above steps, a dyeing step is performed. In the dyeing process, azo compounds represented by formulas (1) and (2), respectively, and other azo compounds as necessary (azo compounds represented by formula (4) above, other organic dyes, etc.) (hereinafter also referred to as "azo compound of formula (1) etc.") can be adsorbed onto a polyvinyl alcohol resin film.

The above dyeing step is not particularly limited as long as it is a method that allows an azo compound such as formula (1) to be adsorbed to a polyvinyl alcohol resin film, but for example, polyvinyl alcohol is added to a solution containing an azo compound such as formula (1). This is done by dipping the resin film. The solution temperature in this dyeing step is preferably 5 to 60°C, more preferably 20 to 50°C, particularly preferably 35 to 50°C. The time for immersion in the solution can be adjusted appropriately, but it is preferably 30 seconds to 20 minutes, more preferably 1 to 10 minutes. As the dyeing method, a method of immersing the polyvinyl alcohol resin film in the above solution is preferred, but a method of applying the solution to the polyvinyl alcohol resin film may also be used.

The solution containing the azo compound of formula (1) etc. can contain sodium carbonate, sodium hydrogen carbonate, sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate, etc. as a dyeing aid. The content of the dyeing aid can be adjusted to any concentration depending on the dyeing property and the dyeing time and temperature, but is preferably 0 to 5% by weight, more preferably 0.1 to 2% by weight.

After the dyeing process, a cleaning process (hereinafter referred to as "cleaning process 1") can be performed. The cleaning process 1 is a process in which the dye solvent adhering to the surface of the polyvinyl alcohol resin film during the dyeing process is cleaned with a cleaning liquid. By performing the washing step 1, it is possible to suppress migration of the dye into the liquid to be treated next. In the cleaning step 1, water is generally used as the cleaning liquid. The specific step of the cleaning step 1 is not particularly limited, and a method of immersing the film in a cleaning liquid is preferable, but a method of applying a cleaning liquid to the polyvinyl alcohol resin film can also be used. The time required for washing step 1 is not particularly limited, but is preferably 1 to 300 seconds, more preferably 1 to 60 seconds. The temperature of the cleaning solution in the cleaning step 1 needs to be a temperature at which the hydrophilic polymer does not dissolve, and is generally 5 to 40°C.

After the dyeing step or after the washing step 1, a step of including at least one crosslinking agent and/or waterproofing agent in the polyvinyl alcohol resin film can be performed. 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. Titanium compounds such as oxysulfate can be used, and ethylene glycol glycidyl ether, polyamide epichlorohydrin, etc. can also be used, but boric acid is preferred. Examples of the water resistance agent include succinic peroxide, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride, and magnesium chloride.

The crosslinking agent and/or the waterproofing agent used in the step of including the crosslinking agent and/or the waterproofing agent in the polyvinyl alcohol resin film are usually used in the form of a solution dissolved in a solvent. The solvent is preferably water, but is not limited thereto. In this step, the concentration of the crosslinking agent and/or waterproofing agent in the solution is preferably 0.1 to 6.0% by weight, and 1.0 to 6.0% by weight based on the solvent, taking boric acid as an example. 4.0% by weight is more preferred. The temperature of the solution used in this step is preferably 5 to 70°C, more preferably 5 to 50°C. A preferred method for incorporating a crosslinking agent and/or a water-resistant agent into a polyvinyl alcohol-based resin film is to immerse the polyvinyl alcohol-based resin film in a solution of a cross-linking agent and/or a water-resistant agent. A method of applying or coating a resin film may also be used. The time required for this step is preferably 30 seconds to 6 minutes, more preferably 1 to 5 minutes. However, it is not essential to include a cross-linking agent and/or a water-resistant agent in the polyvinyl alcohol resin film, and in cases such as when you want to shorten the manufacturing time of polarizing elements or when cross-linking treatment or water-resistant treatment is unnecessary, etc. , this step may be omitted.

A stretching step is performed after the dyeing step, or after the washing step 1, or after the step of adding the crosslinking agent and/or waterproofing agent. The stretching step is a step of uniaxially stretching the polyvinyl alcohol resin film. The stretching method may be either a wet stretching method or a dry stretching method. The present invention can be achieved if the stretching ratio is 3 times or more, but it is preferably 5 times to 7 times. The stretching process can be performed by one stage of stretching, but can also be performed by two or more stages of stretching.

In the case of the above dry stretching method, when the stretching heating medium is an air medium, the temperature of the air medium during stretching is preferably room temperature to 180°C. Further, it is preferable to perform the stretching treatment in an atmosphere with a humidity of 20 to 95% RH. Specific stretching methods include, but are not limited to, for example, an inter-roll zone stretching method, a roll heating stretching method, a rolling stretching method, an infrared heating stretching method, and the like.

In the case of the above wet stretching method, a polyvinyl alcohol resin film is stretched in water, a water-soluble organic solvent, or a mixed solution thereof, and the polyvinyl alcohol resin film is placed in a solution containing the crosslinking agent and/or water resistant agent. It is preferable to carry out the stretching treatment while immersing the film. As the crosslinking agent and/or the water resistance agent, those described above can be used, but boric acid or borax is preferable, and boric acid is particularly preferable. A polyvinyl alcohol resin film is stretched in a solution containing at least one crosslinking agent and/or a waterproofing agent. The concentration of the crosslinking agent and/or waterproofing agent in the stretching step is, for example, preferably 0.5 to 15% by weight, more preferably 2.0 to 8.0% by weight. The stretching ratio is preferably 2 to 9 times, more preferably 5 to 8 times. The stretching temperature is preferably 40 to 70°C, more preferably 45 to 60°C. The stretching time is usually 30 seconds to 20 minutes, more preferably 1 to 5 minutes. The wet stretching step can be performed by one stage of stretching, but can also be performed by two or more stages of stretching.

After performing the above-mentioned stretching process, a cleaning process (hereinafter referred to as "cleaning process 2") is performed to clean the film surface, since the crosslinking agent and/or waterproofing agent may precipitate or foreign matter may adhere to the film surface. be able to. The time required for the washing step 2 is preferably 1 second to 5 minutes. As the cleaning method in the cleaning step 2, a method of immersing the film in a cleaning liquid is preferred, but a method of applying or coating the polyvinyl alcohol resin film with a cleaning liquid can also be used. The cleaning step 2 can be a one-stage process or can be a multi-stage process of two or more stages. The temperature of the cleaning liquid used in the cleaning step 2 is not particularly limited, but is usually 5 to 50°C, preferably 10 to 40°C.

Solvents that can be used in each of the above steps include, for example, water; dimethyl sulfoxide; N-methylpyrrolidone; methanol, ethanol, propanol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, Examples include, but are not limited to, solvents such as alcohols such as methylolpropane; and amines such as ethylenediamine and diethylenetriamine. It is also possible to use a mixture of two or more of these solvents. The most preferred solvent is water.

After the above-mentioned stretching step or washing step 2, a drying step of the polyvinyl alcohol resin film is performed. Natural drying can be used as the drying process, but in order to further increase the drying efficiency, surface moisture can be removed by compression with rolls, air knives, water absorbing rolls, etc. Alternatively, air drying can be performed instead of the moisture removal. The temperature of the drying step is preferably 20 to 100°C, more preferably 60 to 100°C. The time required for the drying step can be in the range of 30 seconds to 20 minutes, but is preferably 5 to 10 minutes.

The polarizing element of the present invention can improve optical properties by using the azo compound represented by formula (1) and the azo compound represented by formula (2) together with the base material. In one embodiment, the polarizing element of the present invention also has excellent durability.

<Polarizing plate>
The polarizing plate of the present invention includes the above polarizing element and a transparent protective layer provided on one or both sides of the polarizing element. The transparent protective layer can be provided as a coating layer of a transparent polymer or as a laminate layer of a transparent film. The transparent polymer or transparent film forming the transparent protective layer is preferably a transparent polymer or transparent film that has high mechanical strength and good thermal stability. Examples of the transparent polymer or transparent film used in the transparent protective layer include cellulose acetate resins such as triacetylcellulose and diacetylcellulose or films thereof, acrylic resins or films thereof, polyvinyl chloride resins or films thereof, nylon resins or films thereof, etc. Films, polyester resins or films thereof, polyarylate resins or films thereof, cyclic polyolefin resins containing cyclic olefins such as norbornene as monomers or films thereof, polyethylene, polypropylene, polyolefins having a cyclo- or norbornene skeleton or copolymers thereof, Examples include polymers (or resins) whose main chain or side chain is imide and/or amide, or films thereof. Moreover, a resin having liquid crystal properties or a film thereof can also be provided as the transparent protective layer. The thickness of the protective film is, for example, about 0.5 to 200 μm. One layer of resin or film may be provided on one side of the polarizing element, two or more layers of the same or different types of resin or film may be provided on one side of the polarizing element, or resins or films of the same or different types may be provided on both sides of the polarizing element. One or more layers may be provided.

An adhesive can be used to bond the transparent protective layer to the polarizing element. The adhesive is not particularly limited, but polyvinyl alcohol adhesive is preferred. Examples of the polyvinyl alcohol adhesive include Gohsenol (registered trademark) NH-26 (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.) and Excelval (registered trademark) RS-2117 (manufactured by Kuraray Co., Ltd.). It is not limited. A crosslinking agent and/or a waterproofing agent can be added to the adhesive. A maleic anhydride-isobutylene copolymer can be mixed with the polyvinyl alcohol adhesive, and in that case, a crosslinking agent can be further mixed therein if necessary. Examples of the maleic anhydride-isobutylene copolymer include Isoban (registered trademark) #18 (manufactured by Kuraray Co., Ltd.), Isoban (registered trademark) #04 (manufactured by Kuraray Co., Ltd.), and ammonia-modified Isoban (registered trademark) #104. (manufactured by Kuraray Co., Ltd.), Ammonia-modified Isoban (registered trademark) #110 (manufactured by Kuraray Co., Ltd.), Imidized Isoban (registered trademark) #304 (manufactured by Kuraray Co., Ltd.), Imidized Isoban (registered trademark) #310 (manufactured by Kuraray Co., Ltd.) (manufactured by the company Kuraray). A water-soluble polyepoxy compound can be used as a crosslinking agent to be mixed into the maleic anhydride-isobutylene copolymer if necessary. Examples of the water-soluble polyepoxy compound include Denacol EX-521 (manufactured by Nagase ChemteX Corporation) and TETRAD (registered trademark)-C (manufactured by Mitsubishi Gas Chemical Corporation). Further, as the adhesive, known adhesives other than the polyvinyl alcohol adhesive, such as urethane adhesive, acrylic adhesive, and epoxy adhesive, can also be used. Additionally, additives such as zinc compounds, chlorides, and iodides can be included in the adhesive at a concentration of about 0.1 to 10% by weight for the purpose of improving the adhesive strength or water resistance of the adhesive. . The additives are not limited either. The polarizing plate can be obtained by bonding a transparent protective layer to one or both sides of the polarizing element using an adhesive, and then drying or heat-treating the layer at an appropriate temperature.

When the polarizing plate is attached to a display device such as a liquid crystal display device or an organic electroluminescent (organic light emitting diode) display device, the polarizing plate may be attached to a display device such as a liquid crystal display device or an organic electroluminescent (organic light emitting diode) display device, if necessary. Various functional layers for corner improvement and/or contrast improvement, and layers or films having brightness improvement properties can also be provided. It is preferable to use an adhesive to bond the polarizing plate to these layers or films or to the display device. Examples of the constituent material of the adhesive layer include materials whose base polymer is an appropriate polymer such as acrylic resin, silicone resin, polyester, polyurethane, polyamide, polyether, fluororesin, rubber, etc., and preferably Examples include acrylic (co)polymer resin compositions using acrylic resins, and techniques using acrylic (co)polymer resin compositions are described in JP-A-59-111114 and JP-A-4-254803. The technology described above is exemplified, but is not particularly limited.

The polarizing plate may include various known functional layers such as an antireflection layer, an antiglare layer, and a hard coat layer on the other surface of the transparent protective layer, that is, the exposed surface. . In order to produce these various functional layers, coating methods are preferred, but it is also possible to use a method of bonding films having the above functions via the above-mentioned adhesive or the above-mentioned pressure-sensitive adhesive. Further, the functional layer can be a layer or film that controls retardation.

The present invention comprises a polarizing element containing an azo compound represented by formula (1) and an azo compound represented by formula (2) together with a base material, and a transparent protective layer provided on one or both sides of the polarizing element. In the polarizing plate, optical properties are improved by using the azo compound represented by formula (1) and the azo compound represented by formula (2). In one embodiment, the polarizing element of the present invention also has excellent durability against light, heat, and humidity.

<Optical members, etc.>
The polarizing element and polarizing plate of the present invention can be used for optical members, equipment, or devices (optical members, etc.). Optical members using the polarizing element or polarizing plate of the present invention have high contrast. In one embodiment, the optical member or the like of the present invention has high durability and maintains the high contrast for a long period of time.

In addition, the polarizing element and polarizing plate of the present invention are each provided with a protective layer or a functional layer, a support, etc. as necessary, and can be used for liquid crystal projectors, calculators, watches, notebook computers, word processors, liquid crystal televisions, polarized lenses, polarized glasses, etc. It can be used in head-up displays, car navigation systems, organic electroluminescence displays, display devices used in indoor and outdoor measuring instruments and indicators, or similar optical devices.

As a method of applying the polarizing plate of the present invention, the polarizing plate of the present invention may be attached to a support and used as a polarizing plate with a support. Since the support is attached with a polarizing plate, it is preferable that the support has a flat portion. Moreover, since the support is used for optical purposes, a glass molded product is preferable. Examples of the glass molded product include glass plates, lenses, prisms (eg, triangular prisms, cubic prisms, etc.). For example, a lens with a polarizing plate attached can be used as a condenser lens with a polarizing plate in a liquid crystal projector. Furthermore, a prism with a polarizing plate attached can be used as a polarizing beam splitter with a polarizing plate or a dichroic prism with a polarizing plate in a liquid crystal projector. Alternatively, a polarizing plate may be attached to the liquid crystal cell. Examples of the material for the glass molded product include inorganic glasses such as soda glass, borosilicate glass, crystal, and sapphire, and organic polymers such as acrylic resin and polycarbonate, but inorganic glasses are preferred. . The thickness and size of the glass plate may be any desired size depending on the purpose. In addition, in order to further improve single-plate light transmittance, a polarizing plate with a support that includes a support made of glass is provided with an antireflection layer (AR layer) on one or both of the glass surface and the polarizing plate surface. It is preferable. In this case, a transparent adhesive (adhesive) agent is applied to the surface of the support, for example, to the surface of the flat part of the support, and then the polarizing plate of the present invention is attached to this applied surface. Alternatively, a transparent adhesive (adhesive) agent may be applied to the polarizing plate, and then a support may be attached to the coated surface. The adhesive (pressure-sensitive adhesive) used here is preferably, for example, an acrylic ester-based adhesive. Note that when this polarizing plate is used in combination with a retardation plate as an elliptically polarizing plate, the retardation plate side of the elliptically polarizing plate is usually attached to a support; It can also be pasted on the body.

A display device including the polarizing element of the present invention or the polarizing plate of the present invention is also one of the embodiments of the present invention. Furthermore, one particularly preferred application of the polarizing plate of the present invention is a liquid crystal display device. The liquid crystal display device is, for example, a reflective type, a transmissive type, or a transmissive/reflective liquid crystal display comprising a liquid crystal cell and a polarizing element of the present invention or a polarizing plate of the present invention disposed on one or both sides of the liquid crystal cell. It can be a device. It is optional to use the above liquid crystal cell, and for example, an active matrix drive type liquid crystal cell represented by a thin film transistor type, a simple matrix drive type liquid crystal cell represented by a twisted nematic type or a super twisted nematic type, etc. can be used as appropriate. It may be one using a type of liquid crystal cell. A display device equipped with the polarizing element or polarizing plate of the present invention not only provides a high degree of polarization, that is, contrast, but also can provide high durability. Its durability means that it provides a display device that does not discolor or lose contrast even in an environment of 115° C. or 85° C. with a relative humidity of 85%. It is preferable for the display device to have a contrast value of 100 or more and a polarization degree of 98% or more, and more preferably a contrast value of 1000 or more and a polarization degree of 99% or more, and a contrast value of 1100 or more. Moreover, it is extremely preferable that the degree of polarization is 99.9% or more.

Furthermore, in the liquid crystal display device of the present invention, one or more other appropriate optical members such as a prism array sheet, a lens array sheet, a light diffusing plate, and a backlight may be arranged at appropriate positions. When providing the polarizing element of the present invention, the polarizing plate of the present invention, or other optical members, they may be the same on both sides or may be different on both sides.

The liquid crystal display device of the present invention can also have an adhesive layer on one or both sides of the polarizing element of the present invention or the polarizing plate of the present invention for adhesion to other members such as a liquid crystal cell. Any adhesive substance or adhesive can be used to form the adhesive layer, and there is no particular limitation. Examples of the constituent material of the adhesive layer include those in which the base polymer is an appropriate polymer such as acrylic resin, silicone resin, polyester, polyurethane, polyamide, polyether, fluororesin, or rubber.

The liquid crystal display device of the present invention is applicable to all types of liquid crystal display devices such as twisted nematic type (TN), super twisted nematic type (STN), thin film transistor type (TFT), vertical alignment type (VA), and in-plane switching type (IPS). can be used.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. The transmittance, degree of polarization, and contrast value of the polarizing plates obtained in Examples and Comparative Examples were evaluated as follows.

[Method for measuring transmittance and degree of polarization of polarizing plate]
The transmittance of one polarizing plate at each wavelength is the single transmittance Ts, and the transmittance at each wavelength when two polarizing plates are stacked so that their absorption axes are in the same direction is the parallel transmittance Tp. The transmittance at each wavelength when two polarizing plates are stacked so that their absorption axes are perpendicular to each other is the orthogonal transmittance Tc, and the single transmittance corrected for visibility using the chromaticity function (C light source 2° field of view) is Ys, the parallel transmittance corrected by the chromaticity function (C light source 2° field of view) is Yp, and the orthogonal transmittance corrected by the chromaticity function (C light source 2° field of view) is Yc. . The respective transmittances Ts, Tp, Tc, Ys, Yp, and Yc were measured at each wavelength at 5 nm intervals using a spectrophotometer (“U-4100” manufactured by Hitachi High-Technologies Corporation).

The degree of polarization ρy (%) of the polarizing plate was determined from the visibility-corrected parallel transmittance Yp and the visibility-corrected orthogonal transmittance Yc using the following formula (6).

ρy (%) = {(Yp-Yc)/(Yp+Yc)} ^1/2 ×100...(6)

The contrast value CR was calculated from the visibility-corrected parallel transmittance Yp and the visibility-corrected orthogonal transmittance Yc using the following formula (7).

CR=Yp/Yc...(7)

[Example 1]
<Preparation of polarizing element>
A polyvinyl alcohol film (“VF-PE#6000” manufactured by Kuraray Co., Ltd.; hereinafter simply referred to as “film”) having a saponification degree of 99% or more and a film thickness of 60 μm was used as the base material. It was immersed in warm water at 35° C. for 3 minutes to undergo swelling treatment. As the azo compound represented by the above formula (1), Compound Example 1-3 of the present invention (JP-A-8-291259) In Example 1, 6.9 parts of 1-amino-2-methoxy-5-methylbenzene was added to 1-amino-2-methoxy-5-methylbenzene. 0.25 parts by weight (obtained by changing 5.4 parts of 5-methylbenzene) and the azo compound of Compound Example 2-4 of the present application (International Publication No. 1.5 parts by weight of the azo compound of formula (2) described in Compound Example 45 of No. 2012/108169, and the azo compound of Compound Example 4-2 of the present application (International Publication 0.14 parts by weight of the azo compound of formula (2) described in Example 1 of No. 2007/138980, 2.0 parts by weight of sodium tripolyphosphate, and 2000 parts by weight of water were heated at 45°C. An aqueous solution was prepared. The film subjected to the swelling treatment was immersed in this 45° C. aqueous solution, and each of the azo compounds described above was adsorbed onto the film. After washing the film on which each of the above azo compounds was adsorbed with water, it was immersed in an aqueous solution at 40° C. containing 2% by weight of boric acid for 1 minute (boric acid treatment). The film obtained by the boric acid treatment was immersed for 5 minutes in an aqueous solution at 58° C. containing 3.0% by weight of boric acid while being stretched 6.0 times (boric acid treatment). The film obtained by the boric acid treatment was immersed in water at room temperature for 20 seconds while maintaining its tension (cleaning treatment). The film obtained by washing was immediately dried at 60° C. for 5 minutes to obtain a polarizing element with a single transmittance of about 41% and a film thickness of 23 μm. By the above method, a polarizing element using a polyvinyl alcohol film containing an azo compound represented by formula (1), formula (2), and formula (4), respectively, was produced.

<Preparation of polarizing plate>
Polyvinyl alcohol By adhering using an adhesive, a structure of TAC/adhesive layer/polarizing element/adhesive layer/TAC was laminated. Thereby, a polarizing plate was obtained. The obtained polarizing plate was used as a measurement sample.

[Example 2]
As the azo compound represented by the above formula (2), in place of the azo compound of Compound Example 2-4 of Example 1, Compound Example 2-19 of the present invention (International Publication No. 2012/108169 In Example 4, the formula Obtained by synthesis by replacing 7.7 parts of 2,5-dimethylaniline used in the step of obtaining formula (71) from (70) with 9.7 parts of 2,5-dimethoxyaniline) 2.2 A polyvinyl alcohol film containing an azo compound represented by the above formula (1), formula (2), and formula (4), respectively, was used in the same manner as in Example 1, except that part by weight of the azo compound was used. A polarizing element having a single transmittance of about 41% and a film thickness of 23 μm was fabricated, and a polarizing plate was also fabricated and used as a measurement sample.

[Example 3]
As the azo compound represented by the above formula (2), in place of the azo compound of Compound Example 2-4 of Example 1, Compound Example 2-13 of the present application (International Publication No. 2012/108169 In Example 3, the formula Obtained by changing 7.7 parts of 2,5-dimethylaniline used in the step of obtaining formula (71) from (70) to 9.7 parts of 2,5-dimethoxyaniline) 2.1 A polyvinyl alcohol film containing an azo compound represented by the above formula (1), formula (2), and formula (4), respectively, was used in the same manner as in Example 1, except that part by weight of the azo compound was used. A polarizing element having a single transmittance of about 41% and a film thickness of 23 μm was fabricated, and a polarizing plate was also fabricated and used as a measurement sample.

[Example 4]
As the azo compound represented by the above formula (2), in place of the azo compound of Compound Example 2-4 of Example 1, Compound Example 2-17 (International Publication No. 2012/108169 In Example 1, formula 7.7 parts of 2,5-dimethylaniline used in the step of obtaining formula (71) from (70) was replaced with 9.7 parts of 2,5-dimethoxyaniline, and 6-phenylamino- 1.45 parts by weight (obtained by replacing 16.1 parts of 1-naphthol-3-sulfonic acid with 17.6 parts of 6-[(4-hydroxyphenyl)azo]-1-naphthol-3-sulfonic acid) A polyvinyl alcohol film containing an azo compound represented by the above formula (1), formula (2) and formula (4), respectively, was used in the same manner as in Example 1, except that the azo compound was used. A polarizing element having a single transmittance of about 41% and a film thickness of 23 μm was manufactured, and a polarizing plate was also manufactured, and used as a measurement sample.

[Example 5]
As the azo compound represented by the above formula (2), in place of the azo compound of Compound Example 2-4 of Example 1, Compound Example 2-25 of the present application (WO 2012/108173 In Example 2, the formula (obtained by synthesis by changing 7.7 parts of 2,5-dimethylaniline used in the step of obtaining formula (69) from (68) to 9.7 parts of 2,5-dimethoxyaniline) 1.9 A polyvinyl alcohol film containing an azo compound represented by the above formula (1), formula (2), and formula (4), respectively, was used in the same manner as in Example 1, except that part by weight of the azo compound was used. A polarizing element having a single transmittance of about 41% and a film thickness of 23 μm was fabricated, and a polarizing plate was also fabricated and used as a measurement sample.

[Example 6]
As the azo compound represented by the above formula (1), in place of the azo compound of Compound Example 1-3 of Example 1, Compound Example 1-9 of the present invention (JP-A-8-291259 In Example 1, sulfanilic acid 34 Synthesis by changing .6 parts to 36.2 parts of 5-aminoisophthalic acid and changing 6.9 parts of 1-amino-2-methoxy-5-methylbenzene to 5.4 parts of 1-amino-5-methylbenzene. Azo compounds represented by the above formulas (1), (2) and (4), respectively, were prepared in the same manner as in Example 1, except that 0.18 parts by weight of the azo compound (obtained by A polarizing element with a single transmittance of about 42% and a film thickness of 23 μm using a polyvinyl alcohol film containing a compound was prepared, and a polarizing plate was also prepared, and used as a measurement sample.

[Example 7]
As the azo compound represented by the above formula (1), in place of the azo compound of Compound Example 1-3 of Example 1, Compound Example 1-8 of the present invention (JP-A-8-291259 In Example 1, sulfanilic acid 34 .6 parts was changed to 51.0 parts of 2,4-disulfoaniline, and 6.9 parts of 1-amino-2-methoxy-5-methylbenzene was changed to 4.7 parts of aniline, and then 1-hydroxynaphthalene was added. -0.25 part of azo compound (obtained by replacing 15.8 parts of 6-phenylamino-3-sulfonic acid with 12.7 parts of 1-hydroxynaphthalene-6-methylamino-3-sulfonic acid) Single transmittance using a polyvinyl alcohol film containing the azo compounds represented by the above formulas (1), (2), and (4), respectively, in the same manner as in Example 1 except that A polarizing element having a film thickness of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, and used as a measurement sample.

[Example 8]
As the azo compound represented by the above formula (1), in place of the azo compound of Compound Example 1-3 of Example 1, Compound Example 1-17 of the present application (International Publication No. 2015/152026 Formula in Example 1 ( 80) 39.8 parts of 6-(4-aminobenzoylamino)-4-hydroxynaphthalene-2-sulfonic acid used in the synthesis of 6-(4-aminobenzoylamino)-4-hydroxynaphthalene-2-sulfone 0.21 parts of an azo compound (obtained by changing 48.7 parts of acid and 12.1 parts of 3-methylaniline used in the synthesis of formula (81) to 10.5 parts of aniline) Single transmittance using a polyvinyl alcohol film containing the azo compounds represented by the above formulas (1), (2), and (4), respectively, in the same manner as in Example 1 except that A polarizing element having a film thickness of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, and used as a measurement sample.

[Example 9]
As the azo compound represented by the above formula (1), in place of the azo compound of Compound Example 1-3 of Example 1, Compound Example 1-21 of the present application (International Publication No. 2015/152026 Formula in Example 2 ( 82) 39.8 parts of 7-(4-aminobenzoylamino)-4-hydroxynaphthalene-2-sulfonic acid used in the synthesis of 6-(4-aminobenzoylamino)-4-hydroxynaphthalene-2-sulfone The 2,5-dimethylaniline used in the synthesis of formula (84) was changed to 48.7 parts of acid, and 12.1 parts of 2,5-dimethylaniline used in the synthesis of formula (83) was changed to 10.5 parts of aniline. - 9.7 parts of dimethylaniline was replaced with 8.4 parts of aniline, and 17.7 parts of 7-phenylamino-4-hydroxynaphthalene-2-sulfonic acid was replaced with 7-(4-aminobenzoylamino)-4-hydroxy. The above formula (1), the formula (obtained by changing to 20.1 parts of naphthalene-2-sulfonic acid) and the formula ( A polarizing element with a single transmittance of about 42% and a film thickness of 23 μm was fabricated using a polyvinyl alcohol film containing an azo compound represented by formula (2) and formula (4), respectively, and a polarizing plate was fabricated. And so.

[Example 10]
As the azo compound represented by the above formula (4), 0.20 parts by weight of the azo compound described in Compound Example 4-1 of the present invention was used in place of the azo compound of Compound Example 4-2 of Example 1. Other than that, the same procedure as in Example 1 was carried out, using a polyvinyl alcohol film containing the azo compounds represented by the above formulas (1), (2), and (4), respectively, and the single transmittance was about 41%. A polarizing element with a film thickness of 23 μm was produced, and a polarizing plate was also produced, which was used as a measurement sample. In addition, Compound Example 4-1 of the present application was obtained by the following synthesis method. First, 10.8 parts of sulfanilic acid was added to 500 parts of water and dissolved with sodium hydroxide. After cooling to below 10°C, 32 parts of 35% hydrochloric acid was added, followed by 6.9 parts of sodium nitrite, and the mixture was stirred at 5 to 10°C for 1 hour. 20.9 parts of sodium aniline-ω-methanesulfonate was added thereto, and while stirring at 20 to 30°C, sodium carbonate was added to adjust the pH to 3.5. The mixture was further stirred to complete the coupling reaction, and filtered to obtain 17 parts of a monoazo compound. After dissolving 12 parts of the obtained monoazo compound and 21 parts of 4,4'-dinitrostilbene-2,2'-sulfonic acid in 300 parts of water, 12 parts of sodium hydroxide was added and a condensation reaction was carried out at 90°C. . Subsequently, the mixture was reduced with 9 parts of glucose, salted out with sodium chloride, and filtered to obtain 16 parts of an azo compound shown in Compound Example 4-1 of the present invention.

[Example 11]
In place of the azo compound of Compound Example 4-2 of Example 1, C.I. I. Except for using Direct Yellow 28, the single transmittance was measured in the same manner as in Example 1 using a polyvinyl alcohol film containing the azo compounds represented by the above formulas (1) and (2), respectively. A polarizing element having a film thickness of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, which was used as a measurement sample.

[Example 12]
In place of the azo compound of Compound Example 4-2 of Example 1, C.I. I. Except for using Direct Orange 72, the single transmittance was measured in the same manner as in Example 1 using a polyvinyl alcohol film containing the azo compounds represented by the above formulas (1) and (2), respectively. A polarizing element having a film thickness of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, which was used as a measurement sample.

[Comparative example 1]
Using the azo compound described in Example 2 of JP-A No. 11-218611, a polarizing element with a single transmittance of about 40% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, and the produced polarizing plate was measured. It was used as a sample.

[Comparative example 2]
Using the azo compound described in Example 3 of JP-A-2001-033627, a polarizing element with a single transmittance of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, and the produced polarizing plate was measured. It was used as a sample.

[Comparative example 3]
Using the azo compound described in Example 1 of JP-A-2004-251962, a polarizing element with a single transmittance of about 41% and a film thickness of 23 μm was produced, and a polarizing plate was also produced, and the produced polarizing plate was measured. It was used as a sample.

[Comparative example 4]
In place of the azo compound of Compound Examples 1-3 in Example 1, a disazo dye of the same color, C. I. A polarizing element with a single transmittance of about 41% and a film thickness of 23 μm using a polyvinyl alcohol film containing an azo compound was prepared in the same manner as in Example 1, except that 0.2 parts by weight of Direct Red 81 was used. At the same time, a polarizing plate was also produced and used as a measurement sample.

[Comparative example 5]
In place of the azo compound of Compound Example 2-4 in Example 1, Japanese Patent Publication No. 64-5623, which is an azo compound showing the same blue color, was used so that the single transmittance could be adjusted to 41% with the dyeing time of Example 1. A polyvinyl alcohol film containing an azo compound was used in the same manner as in Example 1, except that 0.2 parts by weight of the dye (azo compound) described in Example 1 of the publication was used, and the single transmittance was about 41. %, a polarizing element with a film thickness of 23 μm was prepared, and a polarizing plate was also prepared, which was used as a measurement sample.

<Optical performance evaluation>
Table 1 shows the single transmittance Ys (%), parallel transmittance Yp (%), orthogonal transmittance Yc (%), and polarization degree ρy (%) of the polarizing plates of Examples 1 to 12 and Comparative Examples 1 to 5. ) and the measurement results of contrast value CR are shown.

As can be seen from Table 1, the polarizing plates of Examples 1 to 12 of the present invention are polarizing plates with improved polarization performance and contrast compared to polarizing plates using conventional azo compounds.

<Durability evaluation>
Next, changes in optical properties were confirmed when the polarizing plates of Examples 1 to 12 and Comparative Examples 1 to 5 were held at 115°C for 1000 hours and in an environment of 85°C and 85% humidity for 1000 hours. . As a result, in the polarizing plate of the present application, no decrease in contrast or degree of polarization was observed under environments of 115° C. and 85° C. and 85% RH.

As is clear from the results of Examples 1 to 12 and Comparative Examples 1 to 5 above, it can be seen that the polarizing element and polarizing plate of the present invention have improved optical properties and durability. Therefore, by using this polarizing element or polarizing plate, it is possible to obtain a liquid crystal display device and a polarizing lens that have excellent polarization characteristics and are highly durable.

INDUSTRIAL APPLICABILITY The present invention can provide polarizing elements, polarizing plates, optical members, and the like having optical properties equivalent to or superior to conventional ones. The polarizing element or polarizing plate of the present invention is suitable for use in liquid crystal projectors, calculators, watches, notebook computers, word processors, liquid crystal televisions, polarized lenses, polarized glasses, head-up displays, car navigation systems, organic electroluminescent displays (commonly known as OLEDs), and indoor and outdoor displays. It can be used for display devices used in measuring instruments, display devices, etc., or similar optical devices. A liquid crystal display device including the polarizing element of the present invention or the polarizing plate of the present invention is one embodiment of the present invention. Furthermore, as one particularly preferred use of the polarizing plate of the present invention, a display device equipped with the polarizing element or polarizing plate of the present invention not only provides a high degree of polarization, that is, contrast, but also provides high durability. I can do it. Its durability means that it provides a display device that does not discolor or lose contrast even in an environment of 115° C. or 85° C. with a relative humidity of 85%. Particularly preferred applications include in-vehicle displays, liquid crystal projectors, head-up displays, outdoor displays, and other fields where not only high contrast but also heat resistance, moist heat resistance, and light resistance are required.

Claims (7)

A polarizing element comprising an azo compound represented by formula (1) or a salt thereof, an azo compound represented by formula (2) or a salt thereof, and a base material:

(In formula (1), Ar ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent, and Rr ₁ to Rr ₄ each independently represent a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group or represents a C1-4 alkoxy group having a sulfo group, Xr ₁ is an amino group which may have a substituent, a phenylamino group which may have a substituent, a phenylazo group which may have a substituent, represents a benzoyl group which may have a substituent, a benzoylamino group which may have a substituent, or a naphthotriazole group which may have a substituent; m represents 0 or 1);

(In formula (2), Ab ₁ represents a phenyl group having a substituent or a naphthyl group having a substituent, and when Ab ₁ is a phenyl group having a substituent, the substituent is a sulfo group, a carboxyl group, a C1 -4 alkyl group, C1-4 alkoxy group, C1-4 alkoxy group having a sulfo group, nitro group, benzoyl group, amino group, acetylamino group, and C1-4 alkylamino group-substituted amino group. , Rb ₁ to Rb ₅ each independently represent a hydrogen atom, a C1-4 alkyl group, a C1-4 alkoxy group, or a C1-4 alkoxy group having a sulfo group, and Xb ₁ may have a substituent. Amino group, phenylamino group that may have a substituent, phenylazo group that may have a substituent, benzoyl group that may have a substituent, benzoylamino group that may have a substituent, or substituted represents a naphthotriazole group which may have a group). The azo compound represented by formula (2) or its salt is represented by formula (3)

(In formula (3), Ab ₁ , Rb ₁ to Rb ₅ and Xb ₁ are the same as those described in formula (2) above)
The polarizing element according to claim 1, which is an azo compound represented by or a salt thereof. The polarizing element according to claim 1 or 2, wherein Rb ₅ is a methoxy group. Formula (4)

(In formula (4), Ay ₁ represents a sulfo group, a carboxyl group, a hydroxyl group, a C1-4 alkyl group, or a C1-4 alkoxy group, and Ry ₁ to Ry ₄ each independently represent a hydrogen atom, a C1-4 alkyl group or C1-4 alkoxy group, p represents 1, 2, or 3)
The polarizing element according to any one of claims 1 to 3, further comprising an azo compound represented by: The polarizing element according to any one of claims 1 to 4, wherein the base material is a film containing a polyvinyl alcohol resin. A polarizing plate comprising the polarizing element according to any one of claims 1 to 5 and a transparent protective layer provided on one or both sides of the polarizing element. An optical member, device, or device comprising the polarizing element according to any one of claims 1 to 5 or the polarizing plate according to claim 6.