JP2008009417A - Dye for anisotropic dye film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye useful for an anisotropic dye film provided to a light control device or a display device such as a liquid crystal device or an organic electroluminescence device. <P>SOLUTION: The dye for such an anisotropic dye film is characterized in that the form of a free acid is represented by a formula (1), wherein A<SP>1</SP>and B<SP>1</SP>each independently represent an aromatic hydrocarbon group which may have a substituent: D<SP>1</SP>represents a phenyl group having an amino group which may have a substituent as a substituent; and n represents an integer of 0-2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a light-emitting display element such as a light control element, a liquid crystal element (LCD), or an organic electroluminescence element (OLED), a dye used for a polarizing plate provided in an input / output element such as a touch panel, and the like. In particular, the present invention relates to an anisotropic dye film and a polarizing element.

In the LCD, a linearly polarizing film or a circularly polarizing film is used to control optical rotation and birefringence in display. Also in light emitting display elements such as OLEDs and input / output elements such as touch panels, circularly polarizing films are used to prevent reflection of external light.
Conventionally, iodine has been widely used as a dichroic material in these polarizing films (anisotropic dye films). However, since iodine has a high sublimation property, when used in a polarizing film, its heat resistance and light resistance are not sufficient. Therefore, a polarizing film using an organic dye as a dichroic substance has been studied.

As one method for producing such a polarizing film, for example, in Patent Document 1, an organic dye having dichroism is dissolved or adsorbed in a polymer material such as polyvinyl alcohol and stretched into a film in one direction. The method of orienting the dye to obtain a polarizing film is mentioned.
As another method, for example, in Patent Document 2, a film containing a dye is formed on a substrate such as glass or a transparent film using a wet film forming method, and the dye is applied using an intermolecular interaction or the like. A method of obtaining a polarizing film by aligning is mentioned.

However, in any of these methods, the polarizing film using an organic dye is two-color compared to a polarizing plate using iodine as a dichroic material, although an improvement in the degree of polarization is attempted by improving the dye. There is a problem that sufficient optical performance for use as a polarizing film cannot be obtained, such as a low ratio, a single transmittance, and a low parallel transmittance.
Furthermore, a polarizing film using polyvinyl alcohol is called a frame failure or a frame unevenness in an in-vehicle display element that requires durability at high temperatures such as a large display element such as a liquid crystal television or a car navigation monitor. There is a problem that defects caused by film shrinkage due to temperature and humidity changes occur, and a combination of a polymer material such as modified polyvinyl alcohol (polyvinyl alcohol derivative) and a dichroic substance that solves this problem is important. It is coming.
Japanese Patent Laid-Open No. 3-12606 JP-T 8-511109

  An object of the present invention is to provide an organic dye having a high dichroic ratio useful for an anisotropic dye film such as a polarizing film.

As a result of intensive studies by the present inventors, it has been found that an azo dye having a phenyl group substituted with an amino group at the molecular end is useful as an organic dye used in a polarizing film, and has reached the present invention.
That is, this invention exists in the pigment | dye for anisotropic pigment | dye film | membrane characterized by the form of a free acid being represented by following formula (1).

(In Formula (1), A ¹ and B ¹ each independently represents an aromatic hydrocarbon group which may have a substituent. D ¹ is an amino group which may have a substituent. And n represents an integer of 0 to 2.)

  The dye of the present invention has excellent linearity and is useful for anisotropic dye films, particularly polarizing films that require a polarizing function from the viewpoint of absorption anisotropy. Furthermore, by selecting the type and combination of the terminal group and side substituent of the main axis (transition moment axis) of the dye, it is possible to arbitrarily control the intermolecular interaction between the dye and the polymer material or between the dyes. is there. Moreover, since the pigment | dye of this invention is excellent also in heat resistance, it can be used for the anisotropic pigment | dye film | membrane of the various uses for which heat resistance is required.

The description of the constituent requirements described below is an example (representative example) of the embodiment of the present invention, and the contents are not specified.
The anisotropic dye film referred to in the present invention differs from the electromagnetic properties in any two directions selected from a total of three directions in the three-dimensional coordinate system of the thickness direction of the dye film and any two in-plane orthogonal directions. It is a dye film having anisotropy. Examples of electromagnetic properties include optical properties such as absorption and refraction, and electrical properties such as resistance and capacitance. Examples of the film having optical anisotropy such as absorption and refraction include a linearly polarizing film, a circularly polarizing film, a retardation film, and a conductive anisotropic film.

The anisotropic dye film produced using the dye for anisotropic dye film of the present invention is preferably used for a polarizing film, a retardation film, and a conductive anisotropic film, and more preferably used for a polarizing film. preferable.
(1)
The present invention relates to a dye for an anisotropic dye film, wherein the form of the free acid is represented by the following formula (1).

(In Formula (1), A ¹ and B ¹ each independently represents an aromatic hydrocarbon group which may have a substituent. D ¹ is an amino group which may have a substituent. And n represents an integer of 0 to 2.)
<A ^1>
A ¹ represents an aromatic hydrocarbon group which may have a substituent. Preferred examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group, and a phenyl group is particularly preferable.

Examples of the substituent that A ¹ may have include a halogen atom, a hydroxyl group, a cyano group, a carboamido group, an alkyl group, an alkenyl group, an alkoxy group, an alkyl-substituted amino group, an acyl-substituted amino group, and an anionic dissociative group. Can be mentioned. A ¹ may have ^one of these substituents, or may have two or more.
Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom.

The nitrogen atom of the carboamide group may be further substituted with an alkyl group having 4 or less carbon atoms, but is preferably an unsubstituted carboamido group.
The alkyl group usually has 1 to 4 carbon atoms, preferably 3 or less carbon atoms. Specific examples of the alkyl group include a methyl group and an ethyl group.
The alkenyl group usually has 2 or more and 6 or less carbon atoms, preferably 4 or less. Specific examples of the alkenyl group include a vinyl group and an allyl group.

The alkoxy group usually has 1 to 6 carbon atoms, preferably 4 or less carbon atoms. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, a hydroxyethoxy group, and a 2,3-dihydroxypropoxy group.
Examples of the alkyl-substituted amino group include amino groups substituted with 1 or 2 alkyl groups. The alkyl group is usually an alkyl group having 1 to 6 carbon atoms, preferably 3 or less carbon atoms. Specific examples of the alkyl-substituted amino group include a monomethylamino group, a dimethylamino group, and a monoethylamino group.

Examples of the acyl-substituted amino group include amino groups substituted with 1 or 2 acyl groups. The acyl group is usually an acyl group having 1 to 6 carbon atoms, preferably 3 or less carbon atoms. Specific examples of the acyl-substituted amino group include an acetylamino group.
Examples of the anionic dissociable group include a sulfo group, a carboxy group, and a phosphate group.
These substituents that A ¹ may have may further have substituents as long as they can be substituted, and specifically include alkoxy groups, hydroxyl groups, halogen atoms, sulfo groups, carboxy groups, and the like. Is mentioned. Specific examples of the alkoxy group or the halogen atom are the same as the specific examples of the alkoxy group and the halogen atom exemplified as the substituent that A ¹ may have.

The substituent which A ¹ may have is preferably an anionic dissociable group, more preferably a sulfo group or a carboxy group, and particularly preferably a sulfo group.
The A ^1, a phenyl group or a naphthyl group substituted by an anionic dissociative group is preferred in terms of stability of the solution, a phenyl group substituted by a sulfo group more preferred.
<B ¹ >
B ¹ represents an aromatic hydrocarbon group which may have a substituent. Preferred examples of the aromatic hydrocarbon group include a phenylene group and a naphthylene group, and a phenylene group is particularly preferable.

Examples of the substituent that B ¹ may have are the same as those exemplified as the substituent that A ¹ may have. B ¹ may have ^one of these substituents or two or more.
As the substituent which B ¹ may have, an alkyl group, an alkenyl group and an alkoxy group are preferable, and a methyl group and a methoxy group are particularly preferable.

B ¹ is preferably a phenylene group substituted with an alkyl group and / or an alkoxy group from the viewpoint of dyeability, and more preferably a phenylene group substituted with an alkyl group and an alkoxy group.
In the formula (1), when n is 2, two B ¹ present in one molecule may be the same or different.

<D ¹ >
D ¹ represents a phenyl group having an amino group which may have a substituent as a substituent. The amino group that may have a substituent may have one or two substituents. In the case of having two substituents, the two substituents may be the same or different.

When the amino group which may have a substituent has a substituent, (i) an amino group substituted with an alkyl group which may have a substituent, and (ii) a substituent. It is preferably an amino group substituted with an optionally substituted acyl group or (iii) an amino group substituted with an optionally substituted triazinyl group.
(i) an amino group substituted with an optionally substituted alkyl group
The alkyl group usually has 1 to 4 carbon atoms, preferably 3 or less carbon atoms. Specific examples of the alkyl group include a methyl group and an ethyl group.

More preferably, the amino group substituted with an alkyl group which may have a substituent is an amino group substituted with an alkyl group having a substituent selected from the following substituent group X.
(Substituent group X)
An alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, a group having an N atom, a group having an O atom, a group having an S atom, a halogen atom, an anionic dissociative group
Here, in the substituent group X, examples of the group having an N atom include an amino group, an acylamino group, and a carbamoyl group. Examples of the group having an O atom include an alkoxy group, an acyloxyalkyl group, an acyloxyalkoxy group, and a hydroxyl group. Examples of the group having an S atom include a mercapto group, an alkylthio group, and an alkylsulfonyl group. Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom. Examples of the anionic dissociable group include a sulfo group, a carboxy group, and a phosphate group.

Of these, an amino group substituted with an alkyl group substituted with an anionic dissociative group is preferred, and an amino group substituted with an alkyl group substituted with a carboxy group is particularly preferred.
(ii) an amino group substituted with an optionally substituted acyl group
The acyl group usually has 2 or more and 12 or less carbon atoms, preferably 9 or less carbon atoms.

Examples of the substituent of the acyl group include an alkyl group or an aryl group substituted with a hydroxyl group or an anionic dissociable group.
The amino group substituted with the optionally substituted acyl group is (ii-i) a diacylamino group or (ii-ii) an amino group substituted with an alkyl group and an acyl group. Is preferred.

(ii-i) diacylamino group
Here, the diacylamino group in the present invention refers to a group having a partial structure represented by the following (1-a), and includes a group derived from a cyclic imide. Specific examples include a maleimide group, a phthalimide group, and a naphthylimide group, and a phthalimide group is preferable.

The diacylamino group may have a substituent, and examples of the substituent include a hydroxyl group and an anionic dissociable group, preferably an anionic dissociable group, and more preferably a carboxy group.
(ii-ii) Amino group substituted with alkyl group and acyl group
The alkyl group usually has 1 to 4 carbon atoms, preferably 3 or less carbon atoms. Specific examples of the alkyl group include a methyl group and an ethyl group.

The acyl group usually has 2 or more and 12 or less carbon atoms, preferably 8 or less. Specific examples of the acyl group include an acetyl group and a carboxyethylcarbonyl group.
Specific examples include an amino group substituted with a methyl group and a carboxyethylcarbonyl group.
(iii) an amino group substituted with an optionally substituted triazinyl group
Examples of the substituent that the triazinyl group may have include an alkylamino group substituted with an anionic dissociable group, an alkylthio group substituted with an anionic dissociable group, and an arylamino substituted with an anionic dissociable group Examples of the group include 2-sulfoethylamino group, 2-carboxyethylamino group, and 2,5-disulfophenylamino group.

In addition, D ¹ may further have a substituent other than the amino group, for example, a halogen atom, a hydroxyl group, a cyano group, a carboamido group, an alkyl group, an alkenyl group, an alkoxy group, and an anionic dissociative group. Is mentioned. Specific examples of these groups are the same as those described as specific examples of the substituent that A ¹ may have.
<N>
n represents an integer of 0 to 2. Preferably 1 or 2, more preferably 1.
(2)
In the formula (1), when an amino group which is substituted in the D ¹ is an unsubstituted amino group, from the viewpoint of dyeing property, it is preferably a group represented by the following formula (2).

(In formula (2), A ¹ has the same meaning as in formula (1). B ² has the same meaning as B ¹ in formula (1). R ^{1 to} R ⁴ are each independently hydrogen. An atom, a halogen atom, a hydroxyl group, an alkyl group, an alkenyl group, an alkoxy group, an alkyl-substituted amino group, an acyl-substituted amino group, or an anionic dissociable group, and m represents 0 or 1.)
In formula (2), R ^{1 to} R ⁴ may be the same or different. Specific examples of R ^{1 to} R ⁴ are the same as those described as specific examples of the substituent that A ¹ may have.

<Molecular weight>
The molecular weight of the dye for anisotropic dye film (hereinafter referred to as the dye of the present invention) represented by the formula (1) or (2) is preferably 1500 or less, more preferably 1200 or less in the form of a free acid.
The dye of the present invention is usually a water-soluble dye.
The dye of the present invention may be used as it is in the free acid form (free acid form), or a part of the acid group may be in a salt form. 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 following methods.
1) A strong acid such as hydrochloric acid is added to the aqueous solution of the dye obtained in the salt form, the dye is acidified in the form of a free acid, and the dye is then 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 of performing salt exchange in the form of a salting-out cake by adding a large excess of a neutral salt (for example, lithium chloride) having a desired counter ion to an aqueous solution of a dye obtained in a salt form.
3) An aqueous solution of the dye obtained in the 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 alkaline 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 of performing salt exchange by causing an aqueous solution of a dye obtained in a salt form to act on a strongly acidic cation exchange resin previously treated with an alkaline solution having a desired counter ion (for example, an aqueous lithium hydroxide solution).

Whether the acidic group of the dye of the present invention takes the free acid form or the salt form depends on the pKa of the dye and the pH of the dye solution.
Therefore, the acidic group of the dye for an anisotropic dye film of the present invention is a free acid type, any salt type, and when there are two or more acidic groups, a mixture of the free acid type and the salt type or two or more types of salts. It can take various types, such as a mixture of types. In particular, the acidic group of the dye in the anisotropic dye film is preferably a solution containing a dissociable salt of the base material containing the preferable pH of the composition for anisotropic dye film described later and the dye for anisotropic dye film Under the influence of the treatment, the salt form may be different from that used in the step of forming the anisotropic dye film.
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. Plural kinds may be mixed within one molecule of the compound, or plural kinds may be mixed within the composition.
The preferred type of the acidic group of the dye for the anisotropic dye film of the present invention varies depending on the production process of the dye, the content of the composition for the anisotropic dye film described later, the preferred pH, etc., but has high solubility in water. Is necessary (for example, when a high dye concentration is required in the composition for anisotropic dye film in order to enhance the ability of dye transfer to the base material), a lithium salt, triethylamine salt, It is preferable to have one or more substituted organic amine salts or salts thereof. On the other hand, when low solubility in water is required (for example, when the dye is desired to be precipitated from a dye solution in the dye production process), an alkali such as a free acid type, a sodium salt, a potassium salt, or a calcium salt is used. It is preferable to have one or more earth metal salts or salts thereof.
Specific examples of the dye of the present invention are shown below, but the present invention is not limited thereto. Moreover, the following specific examples are described in the form of a free acid.

The dye of the present invention can be produced according to a method known per se.
For example, no. The pigment | dye shown by (1-1) can be manufactured at the following process.
The sulfanilic acid is diazotized according to a conventional method [for example, Yutaka Hosoda, “New Dye Chemistry” (published on December 21, 1973, published by Gihodo), page 396, page 409], condensed to paracresidine, and the resulting monoazo The compound is further diazotized and condensed again with paracresidine to give the desired dye no. (1-1) is obtained.

  In producing the anisotropic dye film, an anisotropic dye film composition can be used. The composition for anisotropic dye film contains the dye for anisotropic dye film of the present invention, and usually further contains a solvent. In the composition or in the anisotropic dye film described in detail below, the dye for the anisotropic dye film of the present invention can be used alone, but the two other dyes for the anisotropic dye film of the present invention, iodine, etc. Combinations of color substances can also be used. Furthermore, it can be used by mixing with other dyes such as an ultraviolet absorbing dye and a near infrared absorbing dye to such an extent that the orientation is not lowered. Thereby, it is possible to manufacture anisotropic dye films having improved durability, correction of hue, improvement of polarization performance, and various hues.

  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 and isopropyl alcohol, glycols such as ethylene glycol and diethylene glycol, cellosolves such as methyl cellosolve and ethyl cellosolve, N-methylpyrrolidone, N, N-dimethyl. Examples thereof include an aprotic solvent such as formamide alone or a mixed solvent of two or more.

The concentration when the dye is dissolved depends on the solubility of the dye and the concentration of the associated state, but is preferably 0.001% by weight or more, more preferably 0.01% by weight or more, preferably 30% by weight. Hereinafter, it is more preferably 25% by weight or less, particularly preferably 20% by weight or less.
Moreover, since the composition for anisotropic dye films improves the wettability to a base material, applicability | paintability, etc., additives, such as surfactant, can be added as needed. As the surfactant, any of anionic, cationic, and nonionic surfactants can be used. The addition concentration is usually preferably 0.01% by weight or more and 10% by weight or less.

  Furthermore, the anisotropic dye film composition can use additives as necessary in order to improve the dyeability on the substrate. Specifically, Teruzo Asahara, “New dye processing course, Volume 7, Dyeing II”, Kyoritsu Publishing Co., Ltd., published on June 15, 1972, pp. 233 to 251 and Yuya Yamashita and Yoshiro Nemoto Seibundo Shinkosha Co., Ltd., issued on September 5, 1963, pages 94 to 173, etc., and dyeing aids used for dyeing, their methods and the aforementioned interfaces Activators, alcohols, glycols, urea, sodium chloride, inorganic salts such as bow glass, and the like. The addition concentration is usually preferably 0.01% by weight or more and 10% by weight or less.

An anisotropic dye film can be produced using the dye for anisotropic dye film of the present invention. In addition to the pigment for the anisotropic pigment film of the present invention, the anisotropic pigment film may contain other pigments (for example, known blue dichroic dyes, iodine, etc.) and surfactants as described above as necessary. Etc. may be contained. Of course, you may contain combining the pigment | dye represented with the pigment | dye for anisotropic pigment | dye films | membranes of this invention.
(A) A method of dyeing a stretched polymer base material such as polyvinyl alcohol with a solution containing a pigment (a composition for anisotropic pigment film) or the like, or a polymer substrate such as polyvinyl alcohol containing a pigment (B) A solution containing a dye (composition for an anisotropic dye film), etc., on a polymer substrate such as polyvinyl alcohol A method of stretching after dissolving in a solution and forming a film into a film
(C) A dye is dissolved in an appropriate solvent to prepare an anisotropic dye film composition, and a wet film forming method is applied to the surface of various substrates such as a glass plate using the anisotropic dye film composition. A method of obtaining a film by aligning and laminating the dye contained in the composition
And publicly known methods.

When an anisotropic dye film is formed using the dye of the present invention, for example, in any of the methods (a) to (c), the dye is dissolved in an appropriate solvent. As a solvent, the solvent contained in the said composition for anisotropic dye films is mentioned.
In addition, an additive such as a surfactant can be added to the anisotropic dye film composition as necessary to improve the solubility of the dye. As the surfactant, any of anionic, cationic, and nonionic surfactants can be used. The addition concentration is usually preferably 0.01% by weight or more and 10% by weight or less.
In order to form the anisotropic dye film by the method of (c) using the dye of the present invention, after preparing the composition for anisotropic dye film, it is applied to various substrates such as a glass plate and the dye. A known method such as a method obtained by orienting and laminating is employed.

  Specifically, as a wet film formation method, Yuji Harasaki, “Coating Engineering”, Asakura Shoten Co., Ltd., published on March 20, 1971, pages 253-277 and Kunihiro Ichimura, “Creation and Application of Molecular Cooperative Materials” CMC Publishing Co., Ltd., published on March 3, 1998, pages 118 to 149, etc., such as spin coating method, spray coating method, bar Examples of the coating method include a coating method, a roll coating method, a blade coating method, a free span coating method, and a die coating method.

The temperature during application is preferably 0 ° C. or higher and 80 ° C. or lower, and the humidity is preferably about 10% RH or higher and 80% RH or lower. The drying temperature is preferably 0 ° C. or more and 120 ° C. or less, and the humidity is preferably about 10% RH or more and 80% RH or less.
Examples of the base material used in the present invention include glass, triacetate, acrylic, polyester, triacetyl cellulose, and a urethane film. In addition, in order to control the orientation direction of the dichroic dye, the surface of the base material is known from “Liquid Crystal Handbook” Maruzen Co., Ltd., issued October 30, 2000, pages 226 to 239, etc. An alignment treatment layer may be applied by a method.

Since the anisotropic dye film produced by such a method may have a low mechanical strength, a protective layer is provided if necessary. This protective layer is formed by laminating a transparent polymer film such as triacetate, acrylic, polyester, polyimide, triacetyl cellulose, or urethane film, and is practically used.
The thickness of the anisotropic dye film of the present invention, particularly the anisotropic dye film formed on the substrate by the method (c), is preferably 30 μm or less, more preferably 20 μm, usually after drying. Hereinafter, it is most preferably 10 μm or less, preferably 50 nm or more. If this film thickness is less than the above lower limit, it is difficult to obtain a uniform film thickness within the film, and if it exceeds the above upper limit, it is difficult to obtain uniform orientation of the dye molecules within the film.

In addition, as a base material dye | stained with the pigment | dye solution in the said (a) method, and a base material extended | stretched with the pigment | dye in the said (b) method, polyvinyl alcohol-type resin, polyvinyl acetate resin, ethylene / acetic acid A vinyl (EVA) resin, a nylon resin, a polyester resin, etc. are mentioned. Among these, a polymer material having high affinity with a pigment such as polyvinyl alcohol is preferable.
As the kind of polyvinyl alcohol, those having a high molecular weight and a high saponification degree are generally preferred from the viewpoint of optical properties such as polarization degree and dichroism, but it is possible to suppress defects due to shrinkage due to temperature and humidity and optical properties. For the purpose of achieving both environmental performance and environmental resistance, a polyvinyl alcohol derivative can be selected in which the type of dichroic material and the degree of saponification and modification of the polyvinyl alcohol (ratio of hydrophobic copolymer components) are appropriately adjusted. .

As a specific method for controlling the interaction between the polymer material and the dye, for each of the polymer material and the dye, proton-donating —OH, —NH ₂ , —NHR, —NHCO—, —NHCONH—, etc. By combining proton-accepting —N═N—, —OH, —NH ₂ , —NRR ′, —OR, —CN, —C≡C— and an aromatic ring such as a phenyl group or a naphthyl group as a functional group, It can be effective (R and R ′ are optional substituents). Further, by adjusting the density of the functional group, an effect can be obtained in improving dichroism and dyeing property.

Dyeing, film formation and stretching in the methods (a) and (b) can be performed by the following general methods.
In the dyeing bath to which the above-mentioned composition for anisotropic dye film and, if necessary, an inorganic salt such as sodium chloride and bow glass, and a dyeing assistant such as a surfactant are added, usually 35 ° C. or higher, usually 80 ° C. or lower. In general, the polymer film is immersed and dyed for 10 minutes or less, and then treated with boric acid as necessary, followed by drying. Alternatively, a high molecular weight polymer is dissolved in water and / or a hydrophilic organic solvent such as alcohol, glycerin, dimethylformamide, etc., an anisotropic dye film composition is added to perform stock solution dyeing, and this dye stock solution is cast. A dyed film is formed by forming a film by a method, a solution coating method, an extrusion method, or the like. The concentration of the polymer to be dissolved in the solvent varies depending on the type of polymer, but is usually 5% by weight or more, preferably about 10% by weight or more, and usually 30% by weight or less, preferably 20% by weight. It is about the following. The concentration of the dye dissolved in the solvent is usually 0.1% by weight or more, preferably about 0.8% by weight or more, usually 5% by weight or less, preferably 2.5% by weight based on the polymer. % Or less.

  The unstretched film obtained by dyeing and forming a film as described above is stretched in a uniaxial direction by an appropriate method. By performing the stretching treatment, the dye molecules are oriented and dichroism is expressed. As a method of stretching uniaxially, there are a method of stretching by a wet method, a method of stretching by a dry method, a method of compressing and stretching between rolls by a dry method, etc., and any method is used. May be. The draw ratio is 2 to 9 times, but when polyvinyl alcohol and its derivatives are used as the polymer, a range of 2.5 to 6 times is preferable. After the stretching and orientation treatment, boric acid treatment is performed for the purpose of improving the water resistance and the degree of polarization of the stretched film. The boric acid treatment improves the light transmittance and the degree of polarization of the anisotropic dye film. The conditions for the boric acid treatment vary depending on the type of the hydrophilic polymer used and the dye, but generally the boric acid concentration is usually 1% by weight or more, preferably about 5% by weight or more, usually 15%. It is about 10% by weight or less, preferably about 10% by weight or less. Further, the treatment temperature is usually 30 ° C. or higher, preferably 50 ° C. or higher and usually 80 ° C. or lower. When the boric acid concentration is less than 1% by weight or when the treatment temperature is less than 30 ° C., the treatment effect is small, and when the boric acid concentration exceeds 15% by weight or the treatment temperature exceeds 80 ° C. The anisotropic dye film becomes fragile and is not preferable.

The film thickness of the anisotropic dye film obtained by the methods (a) and (b) is usually 50 μm or more, particularly 80 μm or more, preferably 200 μm or less, and particularly preferably 100 μm or less.
Anisotropic dye film uses the anisotropy of light absorption and functions as a polarizing film to obtain linearly polarized light, circularly polarized light, elliptically polarized light, etc., as well as film formation process and selection of composition containing substrate and dye Thus, it can be functionalized as various anisotropic films such as refractive index anisotropy and conduction anisotropy, and a polarizing element applicable to various types and various uses can be obtained.

When the anisotropic dye film is used as a polarizing element, the anisotropic dye film itself produced by the method represented by the above (a) to (c) may be used, or on the dye film. Layers having various functions such as a protective layer, an adhesive layer, an antireflection layer, and a retardation layer may be laminated and used as a laminate.
The polarizing element of the present invention uses the above-mentioned anisotropic dye film. However, the polarizing element may be composed only of an anisotropic dye film, or has an anisotropic dye film on a substrate. A polarizing element may be used. A polarizing element having an anisotropic dye film on a substrate is referred to as a polarizing element including the substrate.

  When the anisotropic dye film is formed on a substrate and used as a polarizing element, the formed anisotropic dye film itself may be used. In addition to the protective layer as described above, an adhesive layer or a reflective layer may be used. Various functions such as prevention layer, alignment film, retardation film function, brightness enhancement film function, reflection film function, transflective film function, layer with optical function such as diffusion film A layer having a function may be laminated by a wet film formation method or the like to be used as a laminate.

These layers having optical functions can be formed, for example, by the following method.
The layer having a function as a retardation film is subjected to, for example, a stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or a process described in Japanese Patent No. 3168850. Can be formed.
In addition, the layer having a function as a brightness enhancement film may be formed by forming a fine hole by a method as described in, for example, JP 2002-169025 A or JP 2003-29030 A, or the center of selective reflection. It can be formed by overlapping two or more cholesteric liquid crystal layers having different wavelengths.

The layer having a function as a reflective film or a transflective film can be formed using a metal thin film obtained by vapor deposition or sputtering.
The layer having a function as a diffusion film can be formed by coating the protective layer with a resin solution containing fine particles.
The layer having a function as a retardation film or an optical compensation film can be formed by applying and aligning a liquid crystal compound such as a discotic liquid crystal compound or a nematic liquid crystal compound.

  The anisotropic dye film using the dye for anisotropic dye film of the present invention exhibits high dichroism, is excellent in dyeability to a substrate, and can obtain a highly heat-resistant polarizing element. From the viewpoint, it can be suitably used for applications requiring high heat resistance such as liquid crystal projectors and in-vehicle display panels as well as liquid crystal displays and organic EL displays.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the following examples, the dichroic ratio was calculated by the following equation after measuring the transmittance of the anisotropic dye film with a spectrophotometer in which a prism polarizer was disposed in the incident optical system.
Dichroic ratio (D) = Az / Ay
Az = -log (Tz)
Ay = -log (Ty)
Tz: transmittance for polarized light in the absorption axis direction of the dye film
Ty: Transmittance for polarized light in the direction of the polarization axis of the dye film (Example 1)
To a suspension containing 52 parts by weight of sulfanilic acid and 79 parts by weight of 35% hydrochloric acid, 90 parts by weight of a 25% aqueous sodium nitrite solution was added under ice cooling, and excess nitrous acid was decomposed with sulfamic acid to obtain a diazo liquid. . This diazo solution was dropped into an aqueous solution containing 41 parts by weight of paracresidine and 32 parts by weight of 35% hydrochloric acid under ice-cooling, and the resulting crystals were filtered to obtain a monoazo dye. The obtained monoazo dye was dissolved in 30% N-methylpyrrolidone water while neutralizing with caustic soda. Further, 25% sodium nitrite aqueous solution was added to the solution, and the solution was added dropwise to 10% hydrochloric acid to add diazo. The excess nitrous acid was decomposed with sulfamic acid to obtain a diazo solution. This diazo solution was dropped into an aqueous solution containing 41 parts by weight of paracresidine and 32 parts by weight of 35% hydrochloric acid under ice-cooling, and the resulting crystals were filtered to obtain the dye (1-1) as a sodium salt. In the aqueous solution of this dye, the maximum absorption wavelength (λmax) at 10 ppm was 489 nm.

(Example 2)
10 parts by weight of the dye (1-1) and 6 parts by weight of trimellitic anhydride were added to 30 parts of pyridine, reacted under reflux, allowed to cool, and then 60 parts of ethanol was added for solid-liquid separation. The solid content was dissolved in water, the pH was adjusted to 1 with 35% hydrochloric acid, and the dye (1-2) was obtained in the form of the free acid. This dye is suspended in water according to a conventional method, neutralized with caustic soda to pH = 10, salted out by adding sodium chloride, dissolved again in water, crystallized by adding isopropanol, filtered and dried. After that, the dye (1-2) was obtained in the form of Na salt. In the aqueous solution of this dye, the maximum absorption wavelength (λmax) at 10 ppm was 370 nm.

(Example 3)
In 100 parts by weight of distilled water, the dye No. 0.05 parts by weight of the sodium salt of the dye (1-1) and 0.02 parts by weight of anhydrous sodium sulfate were added and dissolved by stirring to obtain a dyeing solution. A polyvinyl alcohol film (OPL film) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. is immersed in a dyeing solution at 50 ° C. for 1 minute to dye it, and after washing excess dye in a water bath at 50 ° C., 4 wt% boron at 50 ° C. The film was stretched 6 times in an acid aqueous solution. After stretching, the excess boric acid was washed in a room temperature water bath and blown and dried to obtain an anisotropic dye film. This anisotropic dye film had a maximum absorption wavelength of 555 nm, a single transmittance at that wavelength of 50%, a dichroic ratio of 18, and was found to have high dichroism.
Example 4
Pigment No. An anisotropic dye film was obtained using the same method as in Example 3 except that the sodium salt of the dye (1-2) was used and the dyeing time was 2 minutes. This anisotropic dye film had a maximum absorption wavelength of 465 nm, a single transmittance at that wavelength of 46%, a dichroic ratio of 14, and was found to have high dichroism.
(Example 5)
5 parts of the sodium salt of the dye (1-1) was added to 95 parts of water, dissolved by stirring and filtered to obtain a pH 7 dye aqueous solution (an anisotropic dye film composition).
On the other hand, a glass substrate (75 mm × 25 mm, 1.1 mm thickness, polyimide film thickness of about 800 mm) is preliminarily rubbed with a cloth. Was prepared, and the aqueous dye solution was applied with an applicator having a gap of 30 μm (manufactured by Imoto Seisakusho Co., Ltd.), followed by natural drying to obtain an anisotropic dye film.
The obtained anisotropic dye film had a dichroic ratio of 11 at the maximum absorption wavelength of 490 nm, and had a high dichroic ratio (light absorption anisotropy) capable of functioning sufficiently as a polarizing film.

Claims (5)

A dye for anisotropic dye film, wherein the form of the free acid is represented by the following formula (1).

(In Formula (1), A ¹ and B ¹ each independently represents an aromatic hydrocarbon group which may have a substituent. D ¹ is an amino group which may have a substituent. And n represents an integer of 0 to 2.) Amino phenyl group of D ¹ is an amino group having a substituent is substituted with an amino group, an acyl group optionally having a substituent group substituted with alkyl group which may have a substituent The dye for an anisotropic dye film according to claim 1, which is an amino group substituted with a triazinyl group which may have a group or a substituent. The amino group substituted with an alkyl group which may have the substituent is an amino group substituted with an alkyl group having a substituent selected from the following substituent group X, The dye for anisotropic dye films according to claim 2.
(Substituent group X)
An alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, a group having an N atom, a group having an O atom, a group having an S atom, a halogen atom, an anionic dissociative group The amino group substituted with an acyl group which may have the substituent is a diacylamino group or an amino group substituted with an alkyl group and an acyl group. Dyes for anisotropic dye films. The dye for anisotropic dye film according to claim 1, wherein the dye for anisotropic dye film represented by the formula (1) is a dye represented by the following formula (2).

(In formula (2), A ¹ has the same meaning as in formula (1). B ² has the same meaning as B ¹ in formula (1). R ^{1 to} R ⁴ are each independently hydrogen. An atom, a halogen atom, a hydroxyl group, an alkyl group, an alkenyl group, an alkoxy group, an alkyl-substituted amino group, an acyl-substituted amino group, or an anionic dissociable group, and m represents 0 or 1.)