JP2018106163A - Composition for forming anisotropic dye film, anisotropic dye film, and polarization element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming an anisotropic dye film, wherein the anisotropic dye film formed therewith can be expected to have improved moisture resistance, and wherein the composition contributes to stable production by an improved margin to a storage environment during its production, and also lowers the cost required for the storage environment.SOLUTION: Provided is a composition for forming an anisotropic dye film, wherein the composition comprises a dye and a polymer compound having an acidic group and a basic group.SELECTED DRAWING: None

Description

  INDUSTRIAL APPLICABILITY The present invention is useful for anisotropic dye films formed by a wet film forming method, in particular, polarizing films included in display elements of light control elements, liquid crystal elements (LCDs), and organic electroluminescence elements (OLEDs). The present invention relates to a composition for forming an anisotropic dye film exhibiting high dichroism, an anisotropic dye film, and a polarizing element including the anisotropic dye film.

In the LCD, a linearly polarizing film and a circularly polarizing film are used to control optical rotation and birefringence in display. Also in the OLED, a circularly polarizing film is used for preventing reflection of external light.
Conventionally, iodine has been widely used as a dichroic material in these polarizing films. However, since iodine has a high sublimation property, when used as a polarizing element using a polarizing film, its heat resistance and light resistance are not sufficient. Further, since the extinction color is deep blue, it cannot be said that it is an ideal achromatic polarizing element over the entire visible spectrum region.

In order to obtain an ideal achromatic polarizing element, an anisotropic dye film using an organic dye as a dichroic material has been studied. As anisotropic dye films using organic dyes, conventional polymers impregnated with organic dyes, methods for obtaining films by applying organic dyes on substrates, etc. And a film formed by using a film method.
When using an anisotropic dye film in which an organic dye is impregnated in a conventional polymer, an adhesive layer is provided on the anisotropic dye film, a protective film of the adhesive layer is bonded, and the polarizing film is bonded with the protective film The process of transferring a film | membrane to a display manufacturing line, peeling off a protective film with a display manufacturing line, and bonding an anisotropic pigment | dye film | membrane to a board | substrate etc. is taken. If this is replaced with a method of forming an anisotropic dye film on a substrate such as glass or transparent film by using a wet film forming method, an anisotropic dye obtained by impregnating the above-mentioned conventional polymer with an organic dye Compared with the method using a film, the manufacturing process can be simplified, which is considered to contribute to productivity improvement.

Patent Document 1 discloses an anisotropic dye film forming composition containing a trisazo dye for obtaining an anisotropic dye film having a high dichroic ratio.
In addition, it has been shown that specific dyes are used in combination in order to obtain a high dichroic ratio of the anisotropic dye film. For example, an anisotropic dye film forming composition containing an azo compound having an anthraquinone ring and a disazo dye having a naphthalene ring (Patent Document 2), an anisotropic dye film forming composition containing a disazo dye and a monoazo compound It has also been shown that an anisotropic dye film was obtained using a combination of two kinds of products (Patent Document 3) and disazo dyes (Patent Documents 4 and 5).

  In order to improve the performance of anisotropic dye films, the development of additives has been promoted simultaneously. For example, a composition to which an amino acid or the like is added has been developed for the purpose of improving dichroism and heat resistance (Patent Document 6).

  However, the addition of such a compound has concerns about precipitation, aggregation, cracking, and the like due to fluctuations in humidity, and there is a concern that the moisture resistance will deteriorate.

JP 2010-168570 A JP 2008-101154 A JP 2012-194357 A JP 2007-126628 A International Publication No. 2015/088798 International Publication No. 2005/069048

  An object of the present invention is to develop a composition for forming an anisotropic dye film capable of producing an anisotropic dye film having high moisture resistance.

The present inventors have found that the above problem can be solved by using a composition containing a dye and a specific polymer compound.
That is, the gist of the present invention is as follows.

[1]
An anisotropic dye film-forming composition comprising a dye and a polymer compound having an acidic group and a basic group.
[2]
The composition for forming an anisotropic dye film according to [1], wherein the basic group includes an amino group.
[3]
The composition for forming an anisotropic dye film according to [1] or [2], wherein the acidic group contains a sulfo group.
[4]
[1] to [3], wherein at least a part of the acidic group is a salt-type acidic group, and a counter cation of the salt-type acidic group is a lithium ion and / or a sodium ion. An anisotropic dye film-forming composition.
[5]
The composition for forming an anisotropic dye film according to any one of [1] to [4], wherein the basic group and / or the acidic group does not have an aromatic partial structure.
[6]
An anisotropic dye film formed using the anisotropic dye film forming composition according to any one of [1] to [5].
[7]
A polarizing element comprising the anisotropic dye film according to [6].
[8]
An anisotropic dye film comprising a dye and a polymer compound having an acidic group and a basic group.

  By using the composition for forming an anisotropic dye film of the present invention, improvement in moisture resistance of the formed anisotropic dye film can be expected. In addition to improving the margin for the storage environment at the time of manufacture, it contributes to stable manufacturing, and the storage environment can be made cheaper.

  Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

The anisotropic dye film referred to in the present invention is an electromagnetic property in any two directions selected from a total of three directions in the three-dimensional coordinate system of the thickness direction of the anisotropic dye film and any two orthogonal in-plane directions. Is a dye film having anisotropy. Examples of the electromagnetic property include optical properties such as absorption and refraction, and electrical properties such as resistance and capacitance.
Examples of films having optical anisotropy such as absorption and refraction include polarizing films such as linearly polarizing films and circularly polarizing films, retardation films, and conductive anisotropic dye films. The anisotropic dye film of the present invention is preferably used for a polarizing film, a retardation film and a conductive anisotropic dye film, and more preferably used for a polarizing film.

[Anisotropic Dye Film Forming Composition]
First, the composition for forming an anisotropic dye film of the present invention will be described.
The composition for forming an anisotropic dye film of the present invention includes a dye and a polymer compound having an acidic group and a basic group.
The aspect of the composition for forming an anisotropic dye film is not particularly limited as long as the polymer compound and the dye described above are included. As long as the composition for forming an anisotropic dye film does not cause phase separation, the composition for forming an anisotropic dye film may be a solution, a liquid crystal, or a dispersed state. The liquid crystal phase is preferably from the viewpoint that the anisotropic dye film formed after the solvent evaporates is formed with a high degree of orientation. In the present embodiment, the state of the liquid crystal phase is specifically described on pages 1 to 16 of “Basics and Applications of Liquid Crystals” (Shinichi Matsumoto and Ryo Tsunoda, 1991). As described above, it is a liquid crystal state exhibiting both liquid and crystal properties, which means a nematic phase, a cholesteric phase, a smectic phase, or a discotic phase. In particular, the liquid crystal phase is preferably a nematic phase because the order in the solution tends to be low and the viscosity tends to be low.

[Polymer compound]
The polymer compound that can be used in the present invention is a polymer compound having an acidic group and a basic group (hereinafter sometimes referred to as “polymer compound” in the present specification).
The reason why the effects of the present invention can be obtained by using the polymer compound is presumed as follows.
Basically, the basic group or acidic group has good compatibility with water molecules and has hygroscopicity, so that the anisotropic dye film has a property of easily adsorbing moisture. In the anisotropic dye film, the dye forms an aggregate having a certain size in order to exhibit its anisotropy. Compounds such as amino acids described in Patent Document 6 are presumed to connect and fix this dye aggregate. The compounds such as amino acids that are connected to each other are bonded by weak hydrogen bonds, and the association force is weakened by absorbing moisture. For this reason, it is presumed that the movement of the dye aggregate cannot be suppressed and precipitation and cracking occur. On the other hand, by using the above polymer compound, a part of a weak hydrogen bond network between compounds such as amino acids is replaced with a strong covalent bond. Therefore, it is presumed that even when moisture is adsorbed, the state in which the movement of the dye aggregate is suppressed can be maintained.
In addition, since the anisotropic dye film formed by the dye alone tends to be brittle, the hardness is low, but by adding the above polymer compound, the brittleness is eliminated by the plasticizer effect, and the hardness is improved. Presumed.

About the substituent which the said high molecular compound has, it can explain as follows.
In order to form the anisotropic dye film of the present invention, it is preferable to form a liquid crystalline composition that does not cause phase separation. For this purpose, it is necessary to form a dye aggregate in which the dye and the polymer compound form an aggregate and the dyes are laminated. Although mentioned later, in order to express water solubility, a pigment may have an acidic group or a basic group. Basic groups are usually positively charged or cationic, and acidic groups are usually negatively charged or anionic. Therefore, in order for the dye and the polymer compound to form an association pair, the polymer compound needs to have a basic group or an acidic group. At this time, when the polymer compound has only one of an acidic group and a basic group, it is presumed that either a strong association with the dye or a strong repulsion occurs. In the former case, the dye aggregates are cross-linked through the polymer compound, and it becomes difficult to form a uniform liquid crystal phase. On the other hand, in the latter case, it is presumed that the dye and the polymer compound form their own aggregates because they have the same electric charge, resulting in a phase separation state. Therefore, the polymer compound preferably has a basic group and an acidic group at the same time.

The basic group and acidic group possessed by the polymer compound are as follows.
The acidic group and the basic group are functional groups having a pKa of less than 7 and a basic group of 7 or more, respectively. Note that pKa is a logarithmic value of the reciprocal of the concentration acid dissociation constant Ka, that is, -log Ka.

  As an acidic group which a high molecular compound has, a sulfo group, a carboxyl group, a phosphoric acid group etc. are mentioned, for example. Among these, it is preferable that the acidic group does not have an aromatic partial structure in order to suppress the lamination failure of the dye. In view of maintaining water solubility and improving order, the acidic group preferably contains a sulfo group, and particularly preferably a sulfo group.

  Examples of the basic group include nitrogen-containing basic groups (which preferably include an electron-donating nitrogen atom, and the nitrogen atom preferably has a property of being positively charged or cationic). Amino group (methylamino group, ethylamino group, etc.), pyrrolyl group, 3-pyrrolinyl group, pyrrolidinyl group, pyrazolyl group, 2-pyrazolinyl group, pyrazolidinyl group, imidazolyl group, 1,2,3-triazolyl group, 1,2 , 4-triazolyl group, pyridinyl group, pyridazinyl group, piperidinyl group, pyrazinyl group, piperazinyl group, pyrimidinyl group, triazinyl group and the like. Among these, the basic group preferably does not have an aromatic partial structure, and particularly preferably includes an amino group, and particularly preferably an amino group, in order to suppress the lamination failure of the dye.

A part or all of the acidic group and the basic group contained in the polymer compound may take a salt form.
At least a part of the acidic group may be a salt-type acidic group. As the counter cation of the acidic group, an alkali metal such as sodium, lithium or potassium, an ammonium which may be substituted with an alkyl group or a hydroxyalkyl group And organic amines. Examples of organic amines include lower alkyl amines having 1 to 6 carbon atoms, hydroxy-substituted lower alkyl amines having 1 to 6 carbon atoms, carboxyl-substituted lower alkyl amines having 1 to 6 carbon atoms, and the like. Is mentioned. In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed. From the viewpoint of solubility, an alkali metal salt having a high ionization tendency is desirable. In particular, lithium and / or sodium are preferable, and lithium is particularly preferable from the viewpoint of suppressing the phase separation of the composition containing the pigment and the polymer compound and improving the solubility. Also, lithium is particularly preferable from the viewpoint of increasing the dichroic ratio of a film made of a composition containing a dye and a polymer compound.
At least a part of the basic group may be a salt type basic group. Examples of the basic group salt type include salts of inorganic acids such as hydrochloric acid and sulfuric acid, and salts of organic acids such as acetic acid and formic acid. Is mentioned.

  The molecular weight (weight average molecular weight) of the polymer compound is usually preferably 800 or more, more preferably 1000 or more, and particularly preferably 1400 or more. Further, it is usually preferably 10,000 or less, more preferably 7000 or less, and particularly preferably 5000 or less. For example, 800 or more and 10,000 or less are preferable, 1000 or more and 7000 or less are more preferable, and 1400 or more and 5000 or less are more preferable. When the molecular weight is not less than the above lower limit value, moisture resistance tends to be obtained, and when the molecular weight is not more than the above upper limit value, solubility tends to be obtained.

The main chain of the polymer compound is not particularly limited, but from the compatibility of the dye described later, an amide bond, an ester bond, an ether bond, a —NR ¹ — group (R ¹ is a hydrogen atom, a methyl group or an ethyl group). And a carbon chain containing at least one selected from the group consisting of a sulfonyl group, a carbon chain consisting only of a saturated bond, and the like are preferable, and in particular, a carbon chain consisting only of a saturated bond, an amide bond and / or —NR. It is desirable to have a carbon chain structure containing a ¹ -group. The main chain may have a plurality of the bonds or the groups.
On the other hand, it is desirable not to have a partial structure having aromaticity such as an unsaturated bond or phenylene. By not having a partial structure having an unsaturated bond or aromaticity, the unsaturated bond portion is inhibited from inhibiting the π-π stack of the dye, and the anisotropic dye film-forming composition has liquid crystallinity. Thus, the degree of polarization of the anisotropic dye film tends to be improved.

The side chain of the polymer compound is not particularly limited as in the case of the main chain, but like the main chain, from the compatibility with the dye described later, an amide bond, an ester bond, an ether bond, a —NR ¹ — group ( R ¹ represents a hydrogen atom, a methyl group or an ethyl group) and a carbon chain containing at least one selected from the group consisting of a sulfonyl group, a carbon chain consisting only of a saturated bond, and the like are desirable. In particular, it is desirable to have a carbon chain including at least one selected from the group consisting of a saturated carbon bond, an amide bond, and an —NR ¹ — group.
On the other hand, it is desirable not to have a partial structure having aromaticity such as an unsaturated bond or phenylene. By not having an aromatic bond-like partial structure such as an unsaturated bond or phenylene, inhibition of the π-π stack of the dye is suppressed, and the composition for forming an anisotropic dye film obtains liquid crystallinity. Thus, the degree of polarization of the anisotropic dye film tends to be improved.
Similarly, shorter side chains are preferred. When the side chain is short, inhibition of dye association tends to be suppressed. Therefore, the number of atoms from the side chain to the most distant atom (excluding H atoms) is preferably 2 or more and 10 or less, more preferably 8 or less.
The ratio of the acidic group and the basic group in the same main chain is not particularly limited. From the viewpoint of maintaining liquid crystallinity, the numerical value of basic group / (basic group + acidic group) is preferably greater than 0.05, more preferably 0.1 or more, and even more preferably 0.2 or more. 0.8 or less, more preferably 0.7 or less, still more preferably 0.6 or less, still more preferably 0.5 or less, and even more preferably 0.4 or less. For example, more than 0.05 and 0.8 or less are preferable, 0.1 or more and 0.7 or less are more preferable, 0.2 or more and 0.6 or less are more preferable, and 0.2 or more and 0.5 or less are more preferable. 0.2 to 0.4 is even more preferable. By setting it to the above lower limit or more, the compatibility between the dye and the polymer compound tends to be improved. By setting it to the upper limit value or less, the lamination between the dyes proceeds from the association of the dye and the polymer compound, the liquid crystallinity of the composition is improved, and the polarization degree of the anisotropic dye film tends to be improved.

The combination of the basic group and the acidic group of the polymer compound is not particularly limited. Preferably, the basic group is an amino group, and the acidic group is a sulfo group, a carboxyl group and / or a phosphate group. Furthermore, it is preferable that the basic group is an amino group and the acidic group is a sulfo group. As a basic group, an amino group that has a small skeleton and generates a hard cation according to the HSAB rule when cationized has a strong interaction with the dye, and is less likely to cause phase separation. From the viewpoint of electrostatic repulsion with the dye and suppressing phase separation due to excessive interaction between the dye and the polymer compound, the acidic group is preferably a sulfo group or a phosphate group.
In the case where the polymer compound has a plurality of types of basic groups and acidic groups, the two or more groups may be the same group or different groups.

The polymer compound may have a random structure or a block structure, and particularly preferably has a random structure. Due to the random structure, the compatibility of the polymer compound and the dye tends to be high. Further, it may be a linear polymer or a branched polymer.
Furthermore, the addition of a polymer compound tends to lower the refractive index and extinction coefficient of the anisotropic dye film, so it is anisotropic when the anisotropic dye film is used for a polarizing film or an antireflection film. In some cases, it is possible to reduce interface reflection between the photosensitive dye film and the adjacent layer.

Specific examples of the polymer compound include JP-A No. 2004-027162, JP-A No. 2002-293842, JP-A No. 52-101291, JP-B No. 03-020127, JP-A No. 2004-115675, and the like. Can be produced by the method described in the above publication.
Exemplary compounds of the polymer compound are shown below, but are not limited to the following structures. All counter cations are described in the form of protons, but the counter cations include those described above such as alkali metals. Moreover, the proton form and the salt form may be mixed, or a plurality of salt forms may be included. L, m, and n in the following exemplary compounds represent arbitrary integers.

[Content of polymer compound]
The content of the polymer compound (% by weight in the total solid content) is not particularly limited. The polymer compound is preferably 90% by weight or less, more preferably 80% by weight or less, still more preferably 70% by weight or less, based on the total solid content of the anisotropic dye film-forming composition. It is particularly preferable that it is 60% by weight or less. On the other hand, it is preferably 0.1% by weight or more, more preferably 1% by weight or more, further preferably 3% by weight or more, more preferably 5% by weight or more, more preferably 10% by weight or more, and more preferably 20% by weight or more. 30% by weight or more is particularly preferable, and 40% by weight or more is particularly preferable. For example, it is preferably 0.1% by weight or more and 90% by weight or less, more preferably 1% by weight or more and 90% by weight or less, further preferably 5% by weight or more and 80% by weight or less, and further preferably 10% by weight or more and 70% by weight or less. It is preferably 20% by weight or more and 60% by weight or less, more preferably 30% by weight or more and 60% by weight or less, still more preferably 40% by weight or more and 60% by weight or less. By setting it to the upper limit or less, the degree of polarization of the anisotropic dye film tends to increase. By setting it to the above lower limit or more, brittleness of the anisotropic dye film tends to be suppressed, the hardness is improved, and the reflectance is reduced. It exists in the tendency which is excellent in moisture resistance because it is the said range.

  The blend ratio of the polymer compound and the dye in the composition for forming an anisotropic dye film of the present invention is not particularly limited. It is preferable that it is pigment | dye: high molecular compound = 10: 90-99.9: 0.1. Further, it is more preferably 20:80 to 90:10, further preferably 25:75 to 80:20, and particularly preferably 30:70 to 60:40. By being in the above range, the anisotropic dye film has excellent polarization and moisture resistance, and further tends to suppress brittleness of the anisotropic dye film and improve hardness.

[Dye]
In the present specification, the term “dye” means a substance or compound that absorbs at least part of the wavelength in the visible light region.
As a dye that can be used in the present invention, a water-soluble organic dye or a dichroic dye is used. Moreover, it is preferable that a pigment | dye is a pigment | dye which has liquid crystallinity for orientation control. Here, the pigment having liquid crystallinity means a pigment exhibiting lyotropic liquid crystallinity in a solvent.
The dye exhibiting lyotropic liquid crystallinity used in the present invention is preferably soluble in water or an organic solvent in order to form an anisotropic dye film by coating. Further preferred are compounds having an inorganic value smaller than the organic value as defined in “Organic Conceptual Diagram—Basics and Applications” (Yoshio Koda, Sankyo Publishing, 1984). The term “water-soluble” means that the pigment is dissolved in water at room temperature, usually 0.1% by weight or more, preferably 1% by weight or more.

The above dye preferably has a molecular weight of 200 or more, particularly preferably 300 or more, in a free state that does not take a salt form. Moreover, it is preferable that it is 1500 or less, and it is especially preferable that it is 1200 or less. For example, it is preferably 200 or more and 1500 or less, and particularly preferably 300 or more and 1200 or less.
Moreover, the said pigment | dye may use only 1 type and may be used in combination of 2 or more type.

  Specific examples of the dye include azo dyes (hereinafter also simply referred to as “azo dyes”), stilbene dyes, cyanine dyes, phthalocyanine dyes, condensed polycyclic dyes (perylene dyes, oxazine dyes) Can be mentioned. Among these dyes, azo dyes that can take a high molecular arrangement in the anisotropic dye film are preferable. An azo dye means a dye having at least one azo group. The number of azo groups in one molecule is preferably 2 or more, preferably 6 or less, more preferably 4 or less, and even more preferably 3 or less from the viewpoint of color tone and production. In particular, in an azo dye, having at least one group selected from the group consisting of a sulfo group, a carboxyl group, a phospho group, and a phosphinic acid group can cause the anisotropic dye film to dissolve, drop off, crack, etc. There is a tendency that it is possible to obtain the effect of suppressing the deterioration of the optical characteristics and reducing the deterioration of the optical characteristics. Among these, it is particularly preferable that the azo dye has a sulfo group.

The pigment that can be used in the present invention is not particularly limited, and a known pigment can be used.
Examples of the dye include JP-A-2006-0779030, JP-A-2010-168570, JP-A-2007-302807, JP-A-2008-081700, JP-A-09-230142, JP-A-2007-. No. 272211, JP-A 2007-186428, JP-A 2008-69300, JP-A 2009-169341, JP-A 2009-161722, JP-A 2009-173849, JP-A 2010-039154 JP, JP 2010-180314, JP 2010-266769, JP 2010-031268, JP 2011-012152, JP 2011-016922, JP 2010-100059, JP 2011-141331 A, Special JP-A-2011-190313, JP-T-08-511109, JP-T-2001-504238, JP-A-2006-48078, JP-A-2006-98927, JP-A-2006-193722, JP-A-2006. No. -20878, JP 2005-255846 A, JP 2007-145995 A, JP 2007-126628 A, JP 2008-102417 A, JP 2012-194357 A, JP 2012-194297 A. And JP-A 2011-034061, JP-A 2009-110902, JP-A 2011-100059, JP-2012-194365, JP-A 2011-016920, and the like. .

The dye used in the present invention may be used in the form of a free acid, or a part of the acid group may have a salt form. Further, a salt-type dye and a free acid-type dye may be mixed.
When the dye is obtained in a salt form at the time of production, it may be used as it is or may be converted into a desired salt form (salt exchange). As the salt exchange method, a known method can be arbitrarily used, and examples thereof include the following methods.

1) A strong acid such as hydrochloric acid is added to an aqueous solution of a dye obtained in a salt form, the dye is acidified in the form of a free acid, and then the dye is added with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). A method of neutralizing acidic groups and salt exchange.
2) A method in which a large excess of a neutral salt (for example, lithium chloride) having a desired counter ion is added to an aqueous dye solution obtained in a salt form, and salt exchange is performed in the form of a salting-out cake.
3) An aqueous solution of a dye obtained in a salt form is treated with a strongly acidic cation exchange resin, and the dye is acidified in the form of a free acid, and then an alkali solution having a desired counter ion (for example, an aqueous lithium hydroxide solution). ) To neutralize the acidic group of the dye and perform salt exchange.
4) A method in which an aqueous solution of a dye obtained in a salt form is allowed to act on a strongly acidic cation exchange resin that has been previously treated with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution), thereby performing salt exchange.

Whether the acidic group of the dye is a free acid type or a salt type depends on the pKa of the dye and the pH of the aqueous dye solution. Examples of the salt form include salts of alkali metals such as sodium, lithium and potassium, ammonium salts optionally substituted with an alkyl group or hydroxyalkyl group, and salts of organic amines.
Examples of the organic amine include a lower alkyl amine having 1 to 6 carbon atoms, a hydroxy substituted lower alkyl amine having 1 to 6 carbon atoms, a carboxy substituted lower alkyl amine having 1 to 6 carbon atoms, and the like.
In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed. Moreover, in this invention, although a pigment | dye can be used independently, these 2 or more types may be used together, and it is also possible to mix | blend and use pigments other than the said exemplary pigment | dye to such an extent that orientation is not reduced. it can. Thereby, anisotropic dye films having various hues can be produced.

  Examples of pigments when other pigments are blended (also referred to as “blending pigments”) include C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 34, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 142, C.I. I. Direct Yellow 132, C.I. I. Acid Yellow 9, C.I. I. Acid Yellow 25, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Orange 79, C.I. I. Acid Orange 28, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. DirectRed 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Acid Red 37, C.I. I. Direct Violet 9, C.I. I. Direct Violet 35, C.I. I. Direct Violet 48, C.I. I. Direct Violet 57, C.I. I. Direct Blue 1, C.I. I. Direct Blue 67, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Green 42, C.I. I. Direct Green 51, C.I. I. Examples thereof include dyes described in Direct Green 59, Japanese Patent No. 5092345, and the like.

[Dye concentration in composition for forming anisotropic dye film]
The concentration of the dye in the composition for forming an anisotropic dye film (including a dye for compounding when a dye for blending is used) is preferably 0, although it depends on the film forming conditions of the anisotropic dye film. 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 50% by weight or less, more preferably 30% by weight or less. For example, 0.01 wt% or more and 50 wt% or less are preferable, and 0.1 wt% or more and 30 wt% or less are more preferable. When the dye concentration is within the above range, the viscosity of the composition for forming an anisotropic dye film capable of applying a uniform thin film is obtained, and the dye does not tend to precipitate. In addition, anisotropy such as a sufficient dichroic ratio tends to be obtained in the anisotropic dye film.

[Example of azo dye]
The composition for anisotropic dye film of the present invention may contain an azo dye whose free acid form is represented by the formula (I) as a dye.

[In the formula (I), Ar ¹¹ and Ar ¹² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, Ar ¹³ is a 1,4-phenylene group optionally having an electron donating group, a 1,4-naphthylene group optionally having a substituent, or an aromatic heterocyclic ring optionally having a substituent. And Ar ¹⁴ represents the formula (II). ]

[In Formula (II), R ¹ and R ² each independently have a hydrogen atom, an optionally substituted alkyl group, an optionally substituted phenyl group or a substituent. And b represents an integer of 0 to 3, and d represents 0 or 1. In addition, the group represented by —NR ¹ R ² is substituted at the α-position or the β-position. ]

[Aromatic hydrocarbon group]
Examples of the aromatic hydrocarbon group include groups derived from a single ring and a plurality of rings. The number of rings contained in the groups derived from a plurality of rings is not particularly limited, but is usually 2 or more and 4 or less, preferably 3 or less.
For example, the aromatic hydrocarbon group in Ar ¹¹ has one free valence, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene Ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like. The aromatic hydrocarbon group in Ar ¹² has two free valences, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene. Ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like.

The aromatic hydrocarbon group may have a substituent. Examples of the substituent that may have include a hydrophilic group that is usually introduced to enhance the solubility of the azo compound, and an electron-withdrawing group or electron-donating group that is introduced to adjust the color tone as a dye. preferable.
Examples of the substituent include an alkoxy group, a hydroxyl group, an amino group, an acylamino group, a carbamoyl group, a sulfamoyl group, a carboxy group, a sulfo group, a cyano group, and a phosphate group.

[Aromatic heterocyclic group]
The aromatic heterocyclic group is not particularly limited, but is preferably a group derived from a monocyclic or bicyclic heterocyclic ring from the viewpoint of increasing the degree of polarization. Examples of atoms other than carbon constituting the aromatic heterocyclic group include a nitrogen atom, a sulfur atom, and an oxygen atom. From the viewpoint of increasing the degree of polarization, a nitrogen atom is particularly preferable. When the aromatic heterocyclic group has a plurality of atoms constituting a ring other than carbon, these may be the same or different. Preferable examples include pyridine ring, quinoline ring, isoquinoline ring, thiazole ring, benzothiazole ring and the like.

  The aromatic heterocyclic group may have a substituent. Examples of the substituent that may be included include a hydrophilic group, an electron withdrawing group, an electron donating group, and a hydrogen bonding functional group. Specific examples include an alkyl group, an alkoxy group, an acylamino group, an amino group, a carbamoyl group, a sulfamoyl group, a nitro group, a carboxy group, a sulfo group, a hydroxyl group, a cyano group, and a halogen atom.

[1,4-phenylene group]
Examples of the electron donating group that the 1,4-phenylene group may have include an alkyl group, an alkoxy group, a hydroxyl group, an amino group, and an acetylamino group. Among the electron donating groups that the 1,4-phenylene group may have, the size of the substituent is small, the planarity of the entire azo dye is high, and it is easy to associate, so that a methyl group, a methoxy group, An acetylamino group or an amino group is preferred.

[1,4-naphthylene group]
Specific examples of the substituent that the 1,4-naphthylene group may have include a hydroxyl group, a methyl group, a methoxy group, an acetylamino group, an amino group, a sulfo group, and a carboxy group. Of these, a methoxy group, a sulfo group, or an acetylamino group is preferable because it does not impair the planarity of the entire molecule and exhibits high associative properties.

[Alkyl group]
Examples of the substituent that the alkyl group of R ¹ and R ² may have include an alkoxy group, a hydroxyl group, an amino group, an acylamino group, a carbamoyl group, a sulfamoyl group, a carboxy group, a sulfo group, a cyano group, and a phosphate group. Is mentioned. Specific examples of the alkyl group include lower alkyl groups such as a methyl group, an ethyl group, an n-propyl group, a hydroxyethyl group, and a 1,2-dihydroxypropyl group.

[Phenyl group]
Examples of the substituent that the phenyl group of R ¹ and R ² may have include a methyl group, a methoxy group, a hydroxyl group, a carboxy group, and a sulfo group.

[Acyl group]
The acyl group of R ¹ and R ² is represented by —C (═O) R ³¹ , and R ³¹ represents an alkyl group or a phenyl group. The alkyl group usually has 1 to 4 carbon atoms, preferably 2 or less carbon atoms. The phenyl group usually has 6 or more, usually 10 or less, preferably 8 or less carbon atoms in the substituent. Examples of the substituent that the alkyl group and the phenyl group may have include an alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, a sulfo group, and a carboxy group. Specific examples of the acyl group include an acetyl group and a benzoyl group.

B in the formula (II) is 1 or 2, and the azo dye represented by the formula (I) is likely to be water-soluble, and easily forms an aggregate due to interaction between salts between molecules. It is preferable because of its tendency.
In Formula (II), d is 1, and the azo dye represented by Formula (I) becomes a dye having absorption up to a long wavelength in the visible region (380 nm to 780 nm). This is preferable because it tends to be close to black. In addition, since d is 1, the group represented by —NR ¹ R ² interacts with other substituents in the molecule or between molecules, particularly sulfo groups, so that a strong molecular lamination can be achieved. However, it is preferable.
In the formula (II), the group represented by —NR ¹ R ² is substituted at the α-position or the β-position. Substitution at this position tends to contribute to the intermolecular interaction.
Although not particularly limited, when —SO ₃ H and —NR ¹ R ² are likely to contribute to the intermolecular interaction, the position where the hydroxyl group is substituted is the 1st position, and the position where the azo group is substituted is the 2nd position, It is preferable that at least one of —SO ₃ H or —NR ¹ R ² is substituted at any of the 5, 6, 7, and 8 positions, and at least one is substituted at any of the 6, 7 positions. Is more preferable.

Among them, Ar ¹⁴ is easily represented by the formula (IV), which can easily contribute to the intermolecular interaction, and the obtained anisotropic dye film has an arbitrary color tone with high optical performance. It is particularly preferable because it tends to be changed.

[In Formula (IV), g and h each independently represents 0 or 1. Incidentally, d, R ¹ and R ² in the formula (IV) are the same meanings d of formula (II), R ¹ and R ² and. ]
The sum of g and h is preferably 1 or 2.

[Specific Examples of Azo Dye Represented by Formula (I)]
Specific examples of the azo dye whose free acid form is represented by the formula (I) include, but are not limited to, the dyes described below.

[Another example of azo dye]
By using an azo dye whose free acid form is represented by the formula (III), it can be adjusted to an arbitrary color tone without impairing high optical performance when used as a polarizing film. The color tone can be adjusted appropriately to a desired color tone by adjusting the addition amount, structure, etc. of the azo dye represented by the formula (III).

[In the formula (III), Ar ²¹ and Ar ²² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, n represents 0 or 1. ]

Ar ²¹ has the same meaning as Ar ¹¹ in formula (I), and the preferred range and the substituent that may be present are also the same.

Ar ²² has the same meaning as Ar ¹² in formula (I), and the preferred range and the substituent that may be present are also the same.

[Specific examples of azo dyes in which the form of the free acid is represented by the formula (III)]
Specific examples of the azo dye in which the form of the free acid is represented by the formula (III) include, but are not limited to, the dyes described below.

  In the present invention, an azo dye whose free acid form is represented by formula (I) and an azo dye whose free acid form is represented by formula (III) can be used in combination.

By using these azo dyes in combination, an anisotropic dye film having excellent orientation can be obtained. Also, when the anisotropic dye film composition has a liquid crystal state and is used as a polarizing film without lowering the orientation of the anisotropic dye film obtained by using the anisotropic dye film composition Can provide an anisotropic dye film composition and an anisotropic dye film that can be changed to an arbitrary color tone while having high optical performance. Furthermore, an anisotropic dye film exhibiting an achromatic color can be provided.
A polarizing element using an anisotropic dye film having such characteristics can be used in various fields such as a light control element, a liquid crystal element, and a display element of an organic electroluminescence element that are required to have color reproducibility.

The reason for the effect by the above combination is presumed as follows.
The required functions differ depending on the application form of the anisotropic dye film, but for example, when used as a polarizing film for a display, the color of the polarizing film depends on the color of the backlight light source or color filter used in the display. There is a need to adjust the color tone.
Therefore, by using an azo dye whose free acid type is represented by the formula (I), the anisotropic dye film obtained by forming a preferable association state of the dye exhibits high dichroism, and the dye itself Since it has a wide absorption range, it exhibits dichroism over the entire visible light region. However, in the case of only the azo dye represented by the formula (I), only an anisotropic dye film having a single color tone which the azo dye represented by the formula (I) has a free acid type can be produced.
There are many dyes with different wavelength characteristics from the azo dyes represented by formula (I) in order to change the color tone, but simply adding a different type of dye to the azo dyes represented by formula (I) Then, there is a problem that the concentration at which the composition for an anisotropic dye film becomes a liquid crystal is significantly increased or the orientation of the anisotropic dye film obtained from the composition for an anisotropic dye film is lowered. That is, when used as a polarizing film, the optical performance may deteriorate. This is because when the azo dye represented by the formula (I) is added with another type of dye, the composition for the anisotropic dye film does not form a preferable association state, or the molecular arrangement of the anisotropic dye film is It is presumed to be due to disturbance. Therefore, it is preferable to combine the azo dye represented by the formula (III) with the azo dye represented by the formula (I) from the viewpoint of maintaining the high optical performance of the azo dye and adjusting to an arbitrary color tone. .

[Combination of azo dyes in which the form of the free acid is represented by formula (I) and formula (III)]
In the present invention, the combination of the azo dyes whose free acid forms are represented by formula (I) and formula (III) is not particularly limited.
At least one structure selected from Ar ^{21 to} Ar ²² of formula (III) is a structure excluding the substituent that may be present from at least one structure selected from Ar ^{11 to} Ar ¹⁴ of formula (I) The structure is preferably the same as the structure excluding the substituent which may be included in the structure. For example, when Ar ¹¹ is a naphthalene ring having a cyano group, the structure excluding the substituent which may be present from the structure of Ar ^{11 in} formula (I) is a naphthalene ring. When Ar ²² is a naphthalene ring having a sulfo group, the structure excluding the substituent which may be present from the structure of Ar ^{22 in} formula (III) is a naphthalene ring. In this case, the structure excluding the substituent which may be present from at least one structure selected from Ar ^{11 to} Ar ¹⁴ in the formula (I) is selected from Ar ^{21 to} Ar ^{22 in the} formula (III). It is the same as the structure excluding the substituent that may be present from at least one structure.
Further, the structure excluding the substituent which may be present from at least two structures selected from Ar ^{11 to} Ar ^{14 is present} from at least two structures selected from Ar ^{21 to} Ar ^{22 in the} formula (III). It is preferable that the structures are the same as those except for the substituents that may be present, and the structure excluding the substituents that may be present from at least three structures selected from Ar ^{11 to} Ar ¹⁴ is represented by the formula ( It is preferable that the structure is the same as that of the structure of Ar ^{21 to} Ar ^{22 in} III) except for the substituents that may be present. In addition, the structure except the substituent which may be selected selected from Ar ^{11 to} Ar ¹⁴ may be the same or different. Similarly, the structures selected from Ar ^{21 to} Ar ²² except for the substituents that may be present may be the same or different.
Moreover, the structure except the substituent which may have from at least one structure selected from Ar ^{11 to} Ar ¹⁴ in the formula (I) is from the structure of Ar ²¹ and / or Ar ^{22 in} the formula (III). The structure is preferably the same as the structure excluding the substituent that may have. Further, the structure excluding the substituent which may be present from at least two structures selected from Ar ^{11 to} Ar ¹⁴ of formula (I) is derived from the structure of Ar ²¹ and / or Ar ²² of formula (III). It is preferably the same as the structure excluding the substituent which may be present, and the structure excluding the substituent which may be possessed from the structure of Ar ^{11 to} Ar ^{14 in} the formula (I) is represented by the formula (III It is preferable that it is the same as the structure excluding the substituent which may be present from the structure of Ar ²¹ and / or Ar ²² .

In the combination of the above structures, the group of substituents that may be present is preferably the same, and the substituents that may be possessed are more preferably the same. Moreover, it is preferable that the substitution position of the group of the substituent which may have and / or the substituent which may have is the same.
Further, the bonding position with the azo bond is preferably the same.
The group of substituents refers to the properties of the substituents such as the hydrophilic groups, electron donating groups, electron withdrawing groups, ionic, nonionic, hydrogen bonding functional groups, and functional groups having strong dipoles. Represents a group classified by.
As described above, the structure excluding the substituent that may be present, the group of substituents that may be present, the substituent that may be present, the group of substituents that may be present, and / or Since the substitution positions of the substituents that may be present are the same, intermolecular interactions such as π-π stacking and hydrogen bonding between substituents of the compound of formula (I) and the compound of formula (III) It tends to occur, and the compound of the formula (III) tends to be easily incorporated into the structure of the columnar aggregate formed by the formula (I) and the column aggregate.

On the other hand, at least one combination selected from the group consisting of a combination of Ar ¹¹ and Ar ^21, a combination of Ar ¹² and Ar ^{22, and} a combination of Ar ¹³ and Ar ²² excludes the substituents that may be present. The structures are preferably the same. As a result, intermolecular interactions such as π-π stacking and hydrogen bonding between substituents of the compound of formula (I) and the compound of formula (III) are likely to occur, and the columnar aggregate formed by formula (I) In addition, the compound of formula (III) tends to be easily incorporated into the structure of the column assembly. Further, in the above combination, the group of substituents that may be present is preferably the same, and the substituents that may be possessed are more preferably the same.
The combination of the azo dyes represented by the formula (I) and the formula (III) in the form of the free acid is as described above, whereby the intermolecular interaction of the azo dyes represented by the formula (I) and the formula (III) It becomes easy to do. That is, the compound and the compound of the formula (III) are easily incorporated into the structure of the columnar aggregate or the column aggregate formed by the formula (I).

Specific combinations of the azo dyes in which the form of the free acid is represented by the formula (I) and the formula (III) are not particularly limited, and the specific examples and preferred groups listed above for Ar ^{11 to} Ar ¹⁴ The specific examples and preferred groups listed above for Ar ^{21 to} Ar ²² can be appropriately combined.
Among these, it is particularly preferable to combine each group of Ar ^{11 to} Ar ¹⁴ and Ar ^{21 to} Ar ²² listed below.
A phenyl group or a naphthyl group, wherein Ar ¹¹ has at least one electron withdrawing group as a substituent.
Ar ¹² may have a 1,4-naphthylene group which may have a substituent or an aromatic heterocyclic group which may have a bicyclic substituent.
Ar ¹³ is a 1,4-naphthylene group which may have a substituent or an aromatic heterocyclic group which may have a bicyclic substituent.
Ar ¹⁴ is represented by the formula (IV).
Ar ²¹ may have a phenyl group which may have a substituent or a naphthyl group which may have a substituent.
A 1,4-phenylene group in which Ar ²² may have a substituent.
With these combinations, intermolecular interactions such as π-π stacking of the compound of formula (I) and the compound of formula (III) and hydrogen bonding between substituents tend to occur.

[Mass fraction of azo dye whose free acid form is represented by formula (I) and azo dye whose free acid form is represented by formula (III)]
The mass ratio of the azo dye in which the form of the free acid in the composition for anisotropic dye film of the present invention is represented by formula (I) and the azo dye in which the form of the free acid is represented by formula (III) is: There is no particular limitation.
Moreover, by adjusting the mass ratio, the anisotropic dye film can be appropriately adjusted to a desired color tone.
For example, the mass of the azo dye represented by the formula (III) with respect to the azo dye represented by the formula (I) is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Preferably, it is particularly preferably 0.5% by mass or more, and most preferably 1.0% by mass or more.
Moreover, although an upper limit is not specifically limited, For example, it is preferable that it is smaller than 50 mass%. The mass ratio of the azo dye whose free acid form is represented by formula (I) and the azo dye whose free acid form is represented by formula (III) is in an appropriate range. There is a tendency that an associative property of the dye itself is not inhibited and an anisotropic dye film in which the dye is well oriented can be obtained.

[Synthesis of Azo Dye with Free Acid Form Represented by Formula (I) or Formula (III)]
The azo dye whose free acid form is represented by the formula (I) can be produced according to a known method. For example, after the aromatic amine represented by the formula (XI) is diazotized, a coupling reaction is performed with the aromatic amine represented by the formula (X-II), and the compound represented by the formula (X-III) is represented. To obtain a compound. The compound represented by the formula (X-III) is diazotized and then subjected to a coupling reaction with the aromatic amine represented by the formula (X-IV) to obtain the compound represented by the formula (X-V). . After the compound represented by the formula (X-V) is diazotized, the compound represented by the formula (I) can be produced by performing a coupling reaction with the compound represented by the formula (X-VI). .

  The compound in which the form of the free acid is represented by the formula (III) can be produced according to a known method. For example, after diazotizing the compound represented by the formula (XI-I), the compound represented by the formula (XI-II) is subjected to a coupling reaction to produce the compound represented by the formula (III). Can do.

  If necessary, in each step, dissolve or suspend in a good solvent and add a salt such as sodium chloride for salting out. Dissolve or suspend in a good solvent and add a poor solvent for crystallization. It may be purified by washing, separation by column chromatography, or the like.

  The azo dyes in which the free acid form of the present invention is represented by the formulas (I) and (III) may be used in the free acid form, and some of the acid groups are in the salt form. It may be. Further, a salt-type dye and a free acid-type dye may be mixed. Moreover, when it is obtained in a salt form at the time of production, it may be used as it is or may be converted into a desired salt form. As the salt type exchange method, a known method can be arbitrarily used, and examples thereof include the above-described salt exchange methods 1) to 4).

Whether the azo dye represented by the formulas (I) and (III) of the present invention has a free acid type or a salt type depends on the pKa of the dye and the pH of the aqueous dye solution. .
Examples of the salt type include salts of alkali metals such as Na, Li and K, ammonium salts which may be substituted with alkyl groups or hydroxyalkyl groups, and organic amine salts.
Examples of the organic amine include a lower alkyl amine having 1 to 6 carbon atoms, a hydroxy substituted lower alkyl amine having 1 to 6 carbon atoms, a carboxy substituted lower alkyl amine having 1 to 6 carbon atoms, and the like. In the case of these salt types, the type is not limited to one type, and a plurality of types may be mixed.

[Solvent of composition for forming anisotropic dye film]
As the solvent, water, a water-miscible organic solvent, or a mixture thereof is suitable. Specific examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and glycerin, glycols such as ethylene glycol and diethylene glycol, and cellosolves such as methyl cellosolve and ethyl cellosolve. These may be used alone or in admixture of two or more.
When the above solvent is used, the total solid content of the composition for forming an anisotropic dye film is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and preferably 50%. % By mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, particularly preferably 25% by mass or less, for example, preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass. % Or less, more preferably 15% by mass or more and 30% by mass or less, and still more preferably 15% by mass or more and 25% by mass or less. There is a tendency that an anisotropic dye film having a desired film thickness can be formed by setting the above lower limit value or more, and there is a tendency that the film thickness uniformity of the anisotropic dye film is improved by setting the upper limit value or less. is there.

The composition for forming an anisotropic dye film of the present invention may or may not express a lyotropic liquid crystal phase, but only the amount of solvent in the composition for forming an anisotropic dye film when the lyotropic liquid crystal phase is not expressed. It is preferable that the lyotropic liquid crystal phase is expressed by changing the above. The expression of the lyotropic liquid crystal phase is preferable because the dye exhibits a high degree of orientation in the anisotropic dye film and a high dichroic anisotropic dye film tends to be obtained.
It is more preferable that the composition for forming an anisotropic dye film expresses a lyotropic liquid crystal phase because higher orientation in the anisotropic dye film tends to be obtained.

[PH of anisotropic dye film forming composition]
The pH of the composition for forming an anisotropic dye film is not particularly limited, but is preferably 4.0 or more, more preferably 5.0 or more, and most preferably 5.5 or more. Further, it is preferably 12 or less, more preferably 11 or less, and most preferably 10 or less. When the pH value is less than or equal to the above upper limit value, the basic group of the polymer compound is cationized, the compatibility with the dye is improved, and phase separation (precipitation) tends to be suppressed. Further, when the pH value is equal to or higher than the above lower limit, the acidic group is anionized, and in the composition for forming an anisotropic dye film, phase separation due to excessive interaction between the dye and the polymer compound can be suppressed. There is a tendency.

[Additive of composition for forming anisotropic dye film]
If necessary, the composition for forming an anisotropic dye film may further include a surfactant, a leveling agent, a coupling agent, a pH adjuster, alanine, valine, leucine, isoleucine, glycine, glycylglycine, glycylglycyl. Acidic groups and basic groups such as glycine, serine, proline, cysteine, cystine, glutamine, 6-aminohexanoic acid, amino acids described in International Publication No. 2005/069048, 3-amino-1-propanesulfonic acid, taurine Additives such as low molecular weight compounds having Depending on the additive, wettability, applicability, stability of the composition for forming an anisotropic dye film, and the like may be improved.
As the surfactant, any of anionic, cationic and nonionic properties can be used. The addition concentration is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably as the concentration in the composition for forming an anisotropic dye film. It is 0.05 mass% or more. Moreover, Preferably it is 0.8 mass% or less, More preferably, it is 0.5 mass% or less. For example, 0.001% by mass to 0.8% by mass is preferable, 0.01% by mass to 0.5% by mass is more preferable, and 0.05% by mass to 0.5% by mass is further preferable. By being in this range, the effect of adding a surfactant can be obtained, and the orientation of the dye molecules tends not to be inhibited.
For the purpose of suppressing instability such as salt formation and aggregation of anisotropic materials in the composition for forming an anisotropic dye film, a known pH adjuster such as acid / alkali is anisotropically used. May be added either before or after mixing the constituents of the composition for forming a functional dye film or during mixing. As additives other than those described above, “Additive for Coating”, Edited by J. et al. Known additives described in Bieleman, Willy-VCH (2000) can also be used.

[Method for producing composition for forming anisotropic dye film]
The method for producing the composition for forming an anisotropic dye film of the present invention is not particularly limited. For example, a pigment, other additives, a solvent, and the like are mixed, and the pigment is dissolved by stirring and shaking at 0 to 100 ° C. In the case of poor solubility, a homogenizer, a bead mill disperser or the like may be used.
As a manufacturing method of the composition for anisotropic dye film formation of this invention, you may have a filtration process in order to remove the foreign material etc. in a composition. As a method for removing foreign matters or the like in the composition other than filtration, there is a method using centrifugation described in JP 2012-53388 A.

[Anisotropic dye film]
The anisotropic dye film of the present invention can be formed using the anisotropic dye film forming composition of the present invention. The anisotropic dye film of the present invention may contain a dye and a polymer compound having an acidic group and a basic group. The anisotropic dye film of the present invention may contain a dye, a polymer compound having an acidic group and a basic group, and a water-soluble organic compound.
When the anisotropic dye film of the present invention is used as a polarizing element for a liquid crystal display, the orientation characteristics of the anisotropic dye film can be expressed using a dichroic ratio. A dichroic ratio of 8 or more functions as a polarizing element, but is preferably 15 or more, more preferably 20 or more, further preferably 25 or more, and particularly preferably 30 or more. Also, the higher the dichroic ratio, the better. When the dichroic ratio is a specific value or more, it is useful as an optical element described later, particularly as a polarizing element.

The dichroic ratio (D) referred to in the present invention is represented by the following formula when the pigment is uniformly oriented.
D = Az / Ay
Here, Az is the absorbance observed when the polarization direction of the light incident on the anisotropic dye film is parallel to the alignment direction of the pigment, and Ay is the absorbance observed when the polarization direction is perpendicular. . Each absorbance is not particularly limited as long as the same wavelength is used, and any wavelength may be selected depending on the purpose. However, when the degree of orientation of the anisotropic dye film is expressed, the maximum absorption of the anisotropic dye film is used. It is preferable to use a value in wavelength.

Further, the transmittance in the visible light wavelength region of the anisotropic dye film of the present invention is preferably 25% or more. 35% or more is more preferable, and 40% or more is particularly preferable. Moreover, the transmittance | permeability should just be an upper limit according to a use.
For example, when increasing the degree of polarization, the transmittance is preferably 50% or less. When the transmittance is in a specific range, it is useful as the following optical element, and particularly useful as an optical element for a liquid crystal display used for color display.

[Method of forming anisotropic dye film]
The anisotropic dye film of the present invention is preferably produced by a wet film forming method.
The wet film-forming method referred to in the present invention is a method in which a composition for forming an anisotropic dye film is applied on a substrate by any method, and a dye or the like is oriented and laminated on the substrate through a process of drying the solvent. . In the wet film forming method, when the composition for forming an anisotropic dye film is applied on a substrate, the dye itself self-associates in the anisotropic dye film forming composition or in the process of drying the solvent. Causes orientation in a small area. By applying an external field to this state, an anisotropic dye film having desired performance can be obtained by orienting in a certain direction in a macro region. This is different from the method based on the principle that a so-called polyvinyl alcohol (PVA) film or the like is dyed with a solution containing a dye and stretched, and the dye is oriented only by a stretching process. Here, the external field includes the influence of the alignment treatment layer previously applied on the substrate, shear force, magnetic field, and the like, and these may be used alone or in combination.

In addition, the process of applying the anisotropic dye film-forming composition on the substrate to form a film, the process of aligning by applying an external field, and the process of drying the solvent may be performed sequentially or simultaneously. .
Examples of the method for applying the composition for forming an anisotropic dye film on the substrate in the wet film forming method include a coating method, a dip coating method, an LB film forming method, a known printing method, and the like. There is also a method of transferring the anisotropic dye film thus obtained to another substrate. Among these, the present invention preferably uses a coating method.
The orientation direction of the anisotropic dye film is usually coincident with the application direction, but may be different from the application direction. In the present embodiment, the orientation direction of the anisotropic dye film is, for example, a polarizing transmission axis or absorption axis in the case of a polarizing film, and a fast axis or a slow axis in the case of a retardation film. That is.

  The anisotropic dye film in this embodiment functions as a polarizing film or retardation film that obtains linearly polarized light, circularly polarized light, elliptically polarized light, etc. by utilizing the anisotropy of light absorption, as well as a film forming process and a substrate. And by selecting a composition containing an organic compound (pigment or transparent material), it can be functionalized as various anisotropic dye films such as refractive anisotropy and conduction anisotropy.

The method for obtaining the anisotropic dye film by applying the composition for forming the anisotropic dye film is not particularly limited. For example, Yuji Harasaki, “Coating Engineering” (Asakura Shoten Co., Ltd., March 20, 1971). Issued) The method described on pages 253 to 277, supervised by Kunihiro Ichimura, “Creation and Application of Molecular Coordination Materials” (CMC Publishing Co., Ltd., published on March 3, 1998), pages 118 to 149, Slot die coating method, spin coating method, spray coating method, bar coating method, roll coating method, blade coating method, curtain coating method, fountain method, dipping method on a substrate having a step structure (which may be subjected to orientation treatment in advance) The method of apply | coating etc. is mentioned. Among these, the slot die coating method is preferable because an anisotropic dye film with high uniformity can be obtained.
A die coater used in the slot die coating method generally includes a coating machine that discharges a coating solution, a so-called slit die. The slit die is disclosed in, for example, JP-A-2-164480, JP-A-6-154687, JP-A-9-131559, “Basics and Applications of Dispersion / Coating / Drying” (2014, Technosystem Corporation). , ISBN9784924728707 C 305)), "wet coating technology for displays and optical components" (2007, Information Organization, ISBN9784901677752), "precision coating and drying technology in electronics field" (2007, Technical Information Church, ISBN9784861041389), etc. Has been. These known slit dies can be applied even with a flexible member such as a film or a tape or a hard member such as a glass substrate.
The composition for forming an anisotropic dye film of the present invention can be easily supplied to a coating apparatus, and can be applied at a coating speed that can withstand practical use even when applied by the slot die coating method. A highly reliable anisotropic dye film manufacturing process can be constructed.

  Examples of the substrate used for forming the anisotropic dye film of the present invention include glass, triacetate, acrylic, polyester, polyimide, triacetylcellulose, and a urethane film. In addition, in order to control the alignment direction of the dye, the substrate surface is aligned by a known method described in “Liquid Crystal Handbook” Maruzen Co., Ltd., issued October 30, 2000, pages 226 to 239, etc. A treatment layer (alignment film) may be provided. When the alignment treatment layer is provided, it is considered that the dye is oriented due to the influence of the orientation treatment of the orientation treatment layer and the shearing force applied to the composition for forming an anisotropic dye film during coating.

  The method for supplying the composition for forming an anisotropic dye film and the supply interval when applying the composition for forming an anisotropic dye film are not particularly limited. When the anisotropic dye film is thin, it may continuously occur because the supply operation of the coating liquid becomes complicated and the coating film thickness may vary when the coating liquid starts and stops. It is desirable to apply while supplying the composition for forming an anisotropic dye film.

The speed at which the composition for forming an anisotropic dye film is applied is usually 1 mm / second or more, preferably 5 mm / second or more. Moreover, it is 1000 mm / sec or less normally, Preferably it is 200 mm / sec or less. When the coating speed is in an appropriate range, anisotropy of the anisotropic dye film is obtained, and the coating tends to be performed uniformly.
The coating temperature of the composition for forming an anisotropic dye film is usually 0 ° C. or higher and 80 ° C. or lower, preferably 40 ° C. or lower. Moreover, the humidity at the time of application | coating of the composition for anisotropic dye film formation becomes like this. Preferably it is 10% RH or more, More preferably, it is 30% RH or more, Preferably it is 80% RH or less.

  The film thickness of the anisotropic dye film is preferably 10 nm or more, more preferably 50 nm or more, as a dry film thickness. On the other hand, it is preferably 30 μm or less, more preferably 1 μm or less. When the film thickness of the anisotropic dye film is within an appropriate range, uniform orientation and uniform film thickness of the dye tend to be obtained in the film.

The anisotropic dye film may be insolubilized. Insolubilization means a treatment step that increases the stability of the film by controlling the elution of the compound from the anisotropic dye film by reducing the solubility of the compound in the anisotropic dye film.
Specifically, for example, an ion with a lower valence is replaced with an ion with a higher valence (for example, a monovalent ion is replaced with a polyvalent ion), or an organic molecule or polymer having a plurality of ionic groups. A replacement process is listed. As such a processing method, for example, a known method such as a processing step described in Yutaka Hosoda, “Theoretical Manufacturing, Dyeing Chemistry” (Gihodo, 1957), pages 435 to 437 can be used.
Among these, the anisotropic dye film thus obtained is treated by the method described in JP-A-2007-241267, etc. to form an anisotropic dye film that is insoluble in water. From the viewpoint of durability and the like.

[Optical element]
The optical element of the present invention includes the anisotropic dye film of the present invention.
In the present invention, the optical element is a polarizing element that obtains linearly polarized light, circularly polarized light, elliptically polarized light, etc. by utilizing the anisotropy of light absorption, a retardation element, an element having functions such as refractive anisotropy and conduction anisotropy. Represents. These functions can be appropriately adjusted according to the anisotropic dye film forming process and the selection of a composition containing a substrate or an organic compound (a dye or a transparent material). In the present invention, it is most preferably used as a polarizing element.

[Polarizing element]
The polarizing element of the present invention may have any other film (layer) as long as it has the anisotropic dye film of the present invention. For example, it can be produced by providing an alignment film on a substrate and forming an anisotropic dye film on the surface of the alignment film.
Further, the polarizing element is not limited to an anisotropic dye film, but an overcoat layer having functions such as improving polarization performance and improving mechanical strength; adhesive layer or antireflection layer; alignment film; retardation film , A function as a brightness enhancement film, a function as a reflection or antireflection film, a function as a transflective film, a layer having an optical function such as a function as a diffusion film; . Specifically, the layers having various functions described above may be formed by lamination by coating, bonding, or the like, and used as a laminate.
These layers can be provided as appropriate in accordance with the manufacturing process, characteristics, and functions, and the position and order of the layers are not particularly limited. For example, the positions where the above layers are formed may be formed on the anisotropic dye film, or may be formed on the opposite surface of the substrate provided with the anisotropic dye film. On the other hand, the order of forming the above layers may be before or after forming the anisotropic dye film.

These layers having an optical function can be formed by the following method.
The layer having a function as a retardation film can be formed by bonding a retardation film obtained by the following method to another layer constituting the polarizing element.
The retardation film is subjected to, for example, a stretching process described in JP-A-2-59703, JP-A-4-230704, etc., or a process described in JP-A-7-230007. Can be formed.

The layer having a function as a brightness enhancement film can be formed by bonding the brightness enhancement film obtained by the following method to another layer constituting the polarizing element.
For example, the brightness enhancement film is formed of a fine hole by a method described in JP-A No. 2002-169025 and JP-A No. 2003-29030, or two or more layers having different central wavelengths of selective reflection. It can be formed by superposing cholesteric liquid crystal layers.

A layer having a function as a reflective film or a transflective film can be formed by, for example, bonding a metal thin film obtained by vapor deposition or sputtering to another layer constituting the polarizing element. it can.
The layer having a function as a diffusion film can be formed, for example, by coating the other layer constituting the polarizing element with a resin solution containing fine particles.

  The layer having a function as a retardation film or an optical compensation film is obtained by applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound on another layer constituting the polarizing element. Can be formed.

When the anisotropic dye film in the present embodiment is used as an anisotropic dye film for various display elements such as LCDs and OLEDs, it is directly anisotropic on the surface of the electrode substrate or the like constituting these display elements. A dye film can be formed, or a substrate on which an anisotropic dye film is formed can be used as a constituent member of these display elements.
The optical element of the present invention can be suitably used for applications such as a flexible display because a polarizing element can be obtained by forming an anisotropic dye film on a substrate by coating or the like.

EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
Various numerical values such as physical properties, production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiment of the present invention, and the preferred range is the upper limit or lower limit described above. It may be a range defined by a combination of values and values of the following examples or a combination of values of the examples.
In the following description, “part” indicates “part by mass”, and “%” indicates “% by weight”.

Synthesis of Dye-1 8-aminobenzamide was dissolved in 240 parts by weight of water by diazotization by adding 3.00 parts by weight of sodium nitrite to 5.45 parts by weight of water and 200 parts by weight of water under acidic conditions of hydrochloric acid. After coupling with 8.93 parts by weight of 2-naphthalenesulfonic acid (1,7-clebic acid) and pH = 2 to 3, neutralization and salting out were performed, and the precipitated solid was separated by filtration. A wet cake was obtained.
The wet cake of this monoazo compound was dissolved in 220 parts by weight of N-methylpyrrolidone and 110 parts by weight of water, diazotized by adding 3.00 parts by weight of sodium nitrite under acidic conditions of hydrochloric acid, and dissolved in 200 parts by weight of water. After coupling with 8.93 parts by weight of 8-amino-2-naphthalenesulfonic acid (1,7-clebic acid) at pH = 2 to 3, salting out was performed and the precipitate was taken out. By dissolving in water and neutralizing with sodium hydroxide, adding isopropyl alcohol, filtering and separating the precipitated solid, and drying the resulting wet cake, an azo dye represented by the following formula (I-1) is obtained. 31.1 parts by weight of sodium salt were obtained.

  31.3 parts by weight of a sodium salt of an azo dye represented by the formula (I-1) is dissolved in 200 parts by weight of N-methylpyrrolidone and 260 parts by weight of water, and under acidic conditions of hydrochloric acid, 3.04 parts by weight of sodium nitrite. 19.5 parts by weight of 7-amino-1-naphthol-3,6-disulfonic acid (RR acid) (purity: 65.5%) dissolved in 400 parts by weight of water and pH = 9 to 10 was coupled. After the reaction, the precipitated solid was separated by filtration to obtain a sodium salt of (I-2) represented below.

  An aqueous solution of a sodium salt of a trisazo dye represented by the formula (I-2) is passed through a cation exchange resin (SK1BH manufactured by Mitsubishi Chemical Corporation) to make an aqueous solution of a free acid, and then neutralized with an aqueous lithium hydroxide solution and concentrated and dried. As a result, a lithium salt of a trisazo dye represented by the following formula Dye-1 was obtained.

[Comparative Example 1]
Dye-1 and sodium polystyrene sulfonate (weight average molecular weight: 5200) were mixed at a weight ratio of 80:20, and water was added so that the solid concentration was 13%. Then, it stirred for 90 minutes at 80 degreeC, and it was made to melt | dissolve completely, and the composition 1 for anisotropic dye film formation was produced.
Then, when liquid crystal property was confirmed at normal temperature (25 degreeC) using the polarizing microscope, it has confirmed that it was a phase-separation state with which the liquid-crystal part and the non-liquid-crystal part were mixed.

[Comparative Example 2]
An anisotropic dye film-forming composition 2 was prepared in the same manner as in Comparative Example 1 except that sodium polyacrylate (weight average molecular weight: 5000) was used instead of sodium polystyrene sulfonate in Comparative Example 1.
Thereafter, liquid crystal properties were confirmed at room temperature, and it was confirmed that the liquid crystal portion and the non-liquid crystal portion were in a phase separated state.

[Comparative Example 3]
An anisotropic dye film-forming composition 3 was prepared in the same manner as in Comparative Example 1 except that polyallylamine (weight average molecular weight: 3000) was used instead of sodium polystyrene sulfonate in Comparative Example 1.
Thereafter, liquid crystal properties were confirmed at room temperature, and it was confirmed that there was no liquid crystal properties.

[Example 1]
Polymer compound (polymer A) having an acidic group and a basic group, which is a copolymer containing allylamine and sodium allylsulfonate in a molar ratio of 4: 6 instead of sodium polystyrenesulfonate in Comparative Example 1 (weight) An anisotropic dye film-forming composition 4 was prepared in the same manner as in Comparative Example 1 except that the average molecular weight was 1700).
Then, when liquid crystal property was confirmed at normal temperature, it was confirmed that the liquid crystal state was uniform.

[Example 2]
An anisotropic dye as in Example 1 except that the ratio of Dye-1 to Polymer A in Example 1 was changed to 60:40, and that the counter cation of Polymer A was changed to Polymer B salt-exchanged with lithium. A film-forming composition 5 was produced. The polymer A is replaced with a lithium salt by passing an aqueous solution of the polymer A (sodium salt) through a cation exchange resin (SK1BH manufactured by Mitsubishi Chemical Corporation) to make an aqueous solution of free acid, and then the pH is adjusted with an aqueous lithium hydroxide solution. This was carried out by neutralizing to 7.0 and concentrating to dryness.
Then, when liquid crystal property was confirmed at normal temperature, it was confirmed that the liquid crystal state was uniform.

[Comparative Example 4]
An anisotropic dye film-forming composition 6 was prepared in the same manner as in Example 2, except that all of the polymer B in Example 2 was replaced with L-(+)-Lycine.
Then, when liquid crystal property was confirmed at normal temperature, it was confirmed that the liquid crystal state was uniform.

[Moisture resistance test]
The anisotropic dye film-forming compositions prepared in Examples 1 and 2 and Comparative Example 4 were each coated on a glass substrate using an applicator and air-dried to prepare anisotropic dye films.
The obtained anisotropic dye film was left for 1 day in a constant humidity environment adjusted to 25 ° C. and a relative humidity of 97% using a saturated aqueous solution of potassium sulfide. Thereafter, the film was observed with a polarizing microscope, and the moisture resistance was evaluated according to the following criteria.
A: When there is no precipitation, aggregation, or crack in the film B: When there is precipitation, aggregation, or crack in the film

  In the present invention, a saturated aqueous solution of potassium sulfide was created to create a constant humidity environment. At this time, when the hygrometer was confirmed, it was kept at 97% humidity at 25 ° C.

  From these results, it was shown that the composition of the present invention containing a dye and a specific polymer compound can form an anisotropic dye film because it maintains a uniform liquid crystal state. Moreover, it was shown that the obtained anisotropic pigment | dye film | membrane is excellent in moisture resistance.

Claims (8)

  An anisotropic dye film-forming composition comprising a dye and a polymer compound having an acidic group and a basic group.   The composition for forming an anisotropic dye film according to claim 1, wherein the basic group contains an amino group.   The composition for forming an anisotropic dye film according to claim 1 or 2, wherein the acidic group contains a sulfo group.   The at least one part of the said acidic group is a salt-type acidic group, The counter cation of the said salt-type acidic group is a lithium ion and / or a sodium ion as described in any one of Claims 1-3. An anisotropic dye film forming composition.   The composition for forming an anisotropic dye film according to any one of claims 1 to 4, wherein the basic group and / or the acidic group does not have an aromatic partial structure.   An anisotropic dye film formed by using the composition for forming an anisotropic dye film according to claim 1.   A polarizing element comprising the anisotropic dye film according to claim 6.   An anisotropic dye film comprising a dye and a polymer compound having an acidic group and a basic group.