JP5060853B2 - Method for purifying polycyclic compound, method for producing polycyclic compound, and use of polycyclic compound - Google Patents

Description

The present invention relates to a method for purifying a polycyclic compound containing impurities such as sulfate ions, a method for producing a polycyclic compound having a —SO ₃ M group, and uses thereof.

A liquid crystal display device (hereinafter sometimes referred to as LCD) is an element that displays characters and images by utilizing the electro-optical characteristics of liquid crystal molecules. LCDs are widely used in mobile phones, notebook computers, liquid crystal televisions, and the like. However, LCD uses liquid crystal molecules with optical anisotropy, so even if it shows excellent display characteristics in one direction, the screen becomes dark or unclear in the other direction. There is a problem.
Birefringent films are widely used in LCDs in order to solve such problems.
Conventionally, as one of birefringent films, a film in which a refractive index ellipsoid satisfies a relationship of nx>nz> ny is known (for example, see Patent Document 1). This birefringent film is manufactured by sticking a shrinkable film on both sides of a polymer film, and stretching the polymer film so as to expand in the thickness direction by shrinkage of the shrinkable film. For this reason, the birefringent film obtained tends to be thick, and cannot meet the demand for thin and light weight.
JP 2006-072309 A

The present inventors have studied various materials in order to obtain a thin birefringent film excellent in weight reduction, and have found that a polycyclic compound having a —SO ₃ M group is a preferable material. A birefringent film satisfying the relationship of nx ≧ nz> ny can be obtained by dissolving the polycyclic compound in water and coating the aqueous solution on a substrate. Under such knowledge, when the film formation using the polycyclic compound was further studied, when the coating is applied on the substrate, the aqueous solution of the polycyclic compound may not be applied almost uniformly. The inventors of the present invention have made further studies on this cause. As a result, SO ₄ ²⁻ or the like is contained in the aqueous solution of the polycyclic compound, and this presence is the cause of the poor coatability of the aqueous solution. The present invention has been completed.

An object of the present invention is to provide a method for purifying a polycyclic compound that can easily and substantially remove impurities such as sulfuric acid from the polycyclic compound.
Another object of the present invention is to provide a method for producing a polycyclic compound substantially free of impurities such as sulfuric acid.
Another object of the present invention is to provide a coating liquid that contains the above polycyclic compound and can be satisfactorily coated on a substrate.

The first means of the present invention contains an impurity containing at least one of SO ₄ ²⁻ and SO ₃ ^— and a polycyclic compound having a —SO ₃ M group (where M represents a counter ion). In the method of purifying the polycyclic compound from the mixture, the mixture is mixed with an organic solvent in which SO ₄ ²⁻ or SO ₃ ⁻ is dissolved and the polycyclic compound is hardly soluble. And a step of filtering the dispersion and separating the polycyclic compound.

According to the above purification method, SO ₄ ²⁻ and / or SO ₃ ⁻ contained in the polycyclic compound flows out together with the organic solvent as a filtrate, and as a result, the polycyclic compound can be separated as a residue. Therefore, in the present invention, the polycyclic compound can be separated and purified by a relatively simple method called filtration.
The purified polycyclic compound is prepared, for example, as a coating solution. The coating liquid can be satisfactorily coated on the substrate, and a film having a uniform thickness can be produced.

  In a preferred method for purifying a polycyclic compound of the present invention, the organic solvent is at least one selected from methanol, ethanol, isopropyl alcohol, other lower alcohols, and acetone.

  In another preferred method for purifying a polycyclic compound of the present invention, the polycyclic compound contains a quinoxaline derivative represented by the following general formula (I).

式（I）中、Ｍは、対イオンを表す。Ａ及びＢは、置換基を表し、ａ及びｂは、その置換数（ａは０〜４の整数、ｂは、０〜６の整数）を表す。また、ｌ及びｍは、置換数（ｌは、０〜４の整数、ｍは、０〜６の整数）を表す。ただし、ｌ及びｍは、同時に０でない。

In formula (I), M represents a counter ion. A and B represent a substituent, and a and b represent the number of substitutions (a is an integer of 0 to 4, and b is an integer of 0 to 6). L and m represent the number of substitutions (l is an integer of 0 to 4, and m is an integer of 0 to 6). However, l and m are not 0 at the same time.

  Furthermore, in another preferable method for purifying a polycyclic compound of the present invention, the polycyclic compound contains a quinoxaline derivative represented by the following general formula (II).

式（II）中、Ｍは、対イオンを表す。ｍは、置換数（１〜６の整数）を表す。

In formula (II), M represents a counter ion. m represents the number of substitutions (an integer of 1 to 6).

  In another preferred method for purifying a polycyclic compound of the present invention, the polycyclic compound has a maximum value of a light absorption spectrum at a wavelength of 400 nm to 800 nm.

  In another preferable method for purifying a polycyclic compound of the present invention, the polycyclic compound includes a perylene derivative represented by the following general formula (III) or general formula (IV).

式（III）及び式（IV）中、Ｍは対イオンを表す。ｎ１〜ｎ４は、置換基（０〜４の整数）を表す。ただし、ｎ１〜ｎ４の全てが、同時に０でない。

In formula (III) and formula (IV), M represents a counter ion. n1-n4 represents a substituent (integer of 0-4). However, all of n1 to n4 are not 0 at the same time.

  In another preferred method for purifying a polycyclic compound of the present invention, the amount of residual impurities in the polycyclic compound after separation is 100 mg / g or less.

Furthermore, the second means of the present invention relates to a method for producing a polycyclic compound, which is sulfonated to synthesize a polycyclic compound having a —SO ₃ M group (where M represents a counter ion). A step of mixing the compound with an organic solvent in which SO ₄ ²⁻ or SO ₃ ⁻ is dissolved and the polycyclic compound is hardly soluble, obtaining a dispersion, and filtering the dispersion to obtain a polycycle Separating the formula compound.

  A preferable method for producing a polycyclic compound of the present invention uses at least one selected from sulfuric acid, fuming sulfuric acid, and inorganic sulfonic acid as the sulfonation treatment.

  In another preferred method for producing a polycyclic compound of the present invention, the polycyclic compound is a quinoxaline derivative represented by the general formula (I).

  In another preferable method for producing a polycyclic compound of the present invention, the polycyclic compound has a maximum value of a light absorption spectrum at a wavelength of 400 nm to 800 nm.

  In another preferable method for producing a polycyclic compound of the present invention, the polycyclic compound is soluble in water.

  The third means of the present invention relates to a coating solution, and is obtained by dissolving a polycyclic compound separated by any one of the above purification methods or any one of the production methods in water. To do.

A preferred coating liquid of the present invention exhibits a nematic liquid crystal phase.
Other preferred coating liquids of the present invention are adjusted to pH 4-10.

  The fourth means of the present invention relates to a birefringent film, which is obtained by applying any one of the above coating liquids onto a substrate and drying, wherein the refractive index ellipsoid has a relationship of nx ≧ nz> ny. It is characterized by satisfying.

  A fifth means of the present invention relates to a polarizing film, and is obtained by applying any one of the above coating solutions on a substrate and drying.

According to the method for purifying a polycyclic compound and the method for producing a polycyclic compound of the present invention, impurities can be easily removed, and a highly pure polycyclic compound can be obtained.
The polycyclic compound obtained by such a method can be used as a solution to obtain a coating solution that can be satisfactorily applied to a substrate.
A film obtained by coating and drying this coating liquid on a substrate can be used as a birefringent film or a polarizing film.

<Purification method and production method of polycyclic compound>
The method for purifying a polycyclic compound of the present invention is a polycyclic compound having an impurity containing at least one of SO ₄ ²⁻ and SO ₃ ^— and a —SO ₃ M group (where M represents a counter ion). ) And the polycyclic compound can be easily purified.
Hereinafter, the method for purifying the polycyclic compound of the present invention will be described together with the method for producing the polycyclic compound.

(Polycyclic compound)
The polycyclic compound to be subjected to the method of the present invention is not particularly limited as long as it has a —SO ₃ M group, and any polycyclic compound can be targeted. Further, the polycyclic compound may include a —SO ₃ M group and a —COOM group. However, M represents a counter ion (hereinafter, unless otherwise specified, M represents a counter ion). The polycyclic compound to be subjected to the method of the present invention may be one kind or two or more kinds having different structures.
The basic skeleton of the polycyclic compound preferably has two or more aromatic rings and / or heterocyclic rings, and more preferably has 3 to 8 aromatic rings and / or heterocyclic rings. Further, the basic skeleton of the polycyclic compound preferably has at least a heterocyclic ring, and the heterocyclic ring more preferably contains a nitrogen atom. Specifically, examples of the basic skeleton of the polycyclic compound include quinoxaline derivatives and perylene derivatives. These polycyclic compounds are preferable because they exhibit a liquid crystal phase (that is, lyotropic liquid crystal) in a solution state. In addition, this liquid crystal phase is preferably a nematic liquid crystal phase in terms of excellent alignment. This nematic liquid crystal phase includes supramolecules, and the formed body is in a nematic state.
The quinoxaline-based polycyclic compound can be preferably used as a material for forming a birefringent film. The perylene-based polycyclic compound can be preferably used as a material for forming a polarizing film.

Examples of the quinoxaline-based polycyclic compound include acenaphtho [1,2-b] quinoxaline derivatives represented by the following general formula (I). In formula (I), A and B represent substituents, and a and b represent the number of substitutions (a is an integer of 0 to 4, and b is an integer of 0 to 6). L and m represent the number of substitutions (l is an integer of 0 to 4, and m is an integer of 0 to 6). However, l and m are not 0 at the same time, and at least one of them is 1 or more.
M in the general formula (I) represents a counter ion. The M is preferably a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, a metal ion, or a substituted or unsubstituted ammonium ion. Examples of the metal ion include Ni ²⁺ , Fe ³⁺ , Cu ²⁺ , Ag ⁺ , Zn ²⁺ , Al ³⁺ , Pd ²⁺ , Cd ²⁺ , Sn ²⁺ , Co ²⁺ , Mn ²⁺ , and Ce ³⁺ .

The substituents represented by A and B in formula (I) may be the same or different. Examples of the substituent for A and B include a halogen atom, an alkyl group having 1 to 2 carbon atoms, an alkoxy group having 1 to 2 carbon atoms, -OCOCH ₃ group, -NH ₂ group, -NHCOCH ₃ group, -NO ₂ group, -CF ₃ group, -CN group, -OCN group, -SCN group, -COOM group, -CONH ₂ group, -SM group, -OM group and the like can be exemplified (in each group, M is represented by the formula (I ) As well as a counter ion). Preferably, at least one of A and B is a -COOM group (carboxylic acid or a salt thereof). Even if a polycyclic compound has the said substituent represented by A and B, it can be isolate | separated by the method of this invention. In the general formula (I), the substitution numbers a and b are preferably 0 to 2, and more preferably the substitution numbers a and b are 0 to 1. A polycyclic compound in which A and B in the general formula (I) are unsubstituted or have a small number of substitutions exhibits good orientation when coated.

  Examples of the quinoxaline-based polycyclic compound include acenaphtho [1,2-b] quinoxaline derivatives represented by the following general formula (II). In formula (II), m represents the number of substitutions (an integer of 1 to 6). M in the general formula (II) is the same as that in the formula (I). Among the quinoxaline derivatives represented by the general formula (II), a quinoxaline derivative in which m is 1 or 2 can be purified with a high yield by the method of the present invention.

  Examples of perylene-based polycyclic compounds include perylene-based derivatives represented by the following general formula (III) or general formula (IV). In formula (III) and formula (IV), n1 to n4 represent the number of substitutions (an integer of 0 to 4). However, not all of n1 to n4 are simultaneously 0, and at least one of n1 to n4 is an integer of 1 to 4. Preferably, at least one of n1 and n2 is an integer of 1 to 4. M in the above formulas (III) and (IV) is the same as in formula (I). In general formula (III) or general formula (IV), n1-n4 becomes like this. Preferably it is an integer of 0-2, More preferably, it is an integer of 0-1.

Examples of perylene-based polycyclic compounds include perylene-based derivatives represented by the following general formula (V) or general formula (VI). In Formula (V) and Formula (VI), n1 and n2 represent the number of substitutions (an integer of 0 to 4). However, at least one of n1 and n2 is an integer of 1 to 4. M in the above formulas (V) and (VI) is the same as in formula (I). In general formula (V) or general formula (VI), each of n1 and n2 is preferably an integer of 1 or 2. The polycyclic compound represented by the general formula (V) or (VI) has —SO ₃ M groups at both ends in the long axis direction. Such perylene-based polycyclic compounds exhibit good orientation when applied.

  The perylene-based polycyclic compounds represented by the above general formulas (III) to (VI) have the maximum value of the light absorption spectrum in the wavelength range of 400 nm to 800 nm. Such a polycyclic compound is particularly suitable as a material for forming a polarizing film.

(Synthesis of polycyclic compound having a -SO ₃ M group)
The polycyclic compound can be obtained by introducing a —SO ₃ M group (sulfonic acid or a salt thereof) into the basic skeleton of the compound. The —SO ₃ M group can be introduced, for example, by sulfonation treatment.
Synthesis of a quinoxaline-based polycyclic compound includes, for example, a) a method of synthesizing a quinoxaline derivative having an —SO ₃ M group introduced by sulfonating an unsubstituted or substituted quinoxaline derivative with fuming sulfuric acid or the like, b) 1,2-benzenediamine having an unsubstituted or substituted group or / and acenaphthoquinone having an unsubstituted or substituted group are sulfonated with fuming sulfuric acid or the like, and then both compounds are condensed to form —SO ₃ M And a method for obtaining a quinoxaline derivative having a group introduced therein.

As a specific method of the above a), for example, acenaphtho [1,2-b] quinoxaline represented by the following reaction formula (a) or a substituted product thereof is sulfonated with an inorganic sulfonic acid or the like. Examples of the inorganic sulfonic acid include sulfuric acid, fuming sulfuric acid, and chlorosulfonic acid. By such a method, a quinoxaline derivative (polycyclic compound) having a —SO ₃ M group can be obtained. In formula (a), A, a, B, b, l and m are the same as in formula (I) (provided that l and m are not 0 at the same time).

Further, as a specific method of the above b), for example, at least one of 1,2-benzenediamine represented by the following formula (b) or a substituted product thereof, or acenaphthoquinone or a substituted product thereof, an inorganic sulfone is used. After sulfonation with an acid or the like, the benzenediamine and acenaphthoquinone are condensed. Examples of the inorganic sulfonic acid include sulfuric acid, fuming sulfuric acid, and chlorosulfonic acid. By such a method, a quinoxaline derivative (polycyclic compound) having a —SO ₃ M group can be obtained. In formula (b), A, a, B, b, l and m are the same as in formula (I) (provided that l and m are not 0 at the same time).

For example, perylene-based polycyclic compounds can be synthesized by sulphonating a perylene derivative (such as a dibenzimidazole derivative of perylenetetracarboxylic acid) with fuming sulfuric acid or the like to introduce a perylene derivative having an —SO ₃ M group introduced. By doing so, it can be obtained.

(Purification of polycyclic compounds)
In the synthesized product obtained by the above synthesis, impurities that can generate SO ₄ ²⁻ or SO ₃ ⁻ remain, such as sulfuric acid and salts thereof used in the sulfonation treatment, inorganic sulfonic acid, and the like. Since these are non-volatile, they remain in the composite even when dried. The present inventors have found that a compound containing a large amount of impurities such as sulfuric acid in a polycyclic compound cannot form a good coating film even if it is applied as a solution to a substrate. Yes. The cause of this is not clear, but it is presumed that SO ₄ ²⁻ or SO ₃ ⁻ is generated due to residual sulfuric acid or the like when it is made into a solution, which is an obstacle to the formation of a coating film.
In the present invention, in order to substantially and easily remove the impurities in the composition, the compound (polycyclic ring having an impurity such as sulfuric acid and a —SO ₃ M group obtained after sulfonation treatment) is added to the following organic solvent. And the polycyclic compound is purified by filtration separation.

The organic solvent used for purification is a polycyclic compound in which SO ₄ ²⁻ or SO ₃ ⁻ (preferably both SO ₄ ²⁻ and SO ₃ ⁻ are dissolved) and a —SO ₃ M group are hardly soluble. Use a suitable solvent.
Here, _SO ^{4 2-or} SO ₃ ^- and dissolves, _SO ^{4 2-or} SO ₃ in an organic solvent ^- refers to in solubility 23 ° C. of an extent more than 10 g / 100 g. The term “poorly soluble in a polycyclic compound having a —SO ₃ M group” means that the solubility of the polycyclic compound in an organic solvent at 23 ° C. is about 0.5 g / 100 g or less.
Examples of the organic solvent include lower alcohols such as methanol, ethanol and isopropyl alcohol (preferably alcohols having 1 to 4 carbon atoms), acetone and the like. Among these, it is preferable to use methanol or / and acetone. In the present invention, one or more selected from these organic solvents can be used in combination. The reason why water is not used as the solvent is that the polycyclic compound has high solubility in water.

The synthesized product (a mixture containing an impurity such as sulfuric acid and a polycyclic compound having a —SO ₃ M group) is mixed with the organic solvent. The liquid in which the synthesized product is mixed with an organic solvent becomes a dispersion in which a polycyclic compound is dispersed in a solution in which SO ₄ ²⁻ and / or SO ₃ ⁻ is dissolved.
The amount of the organic solvent is not particularly limited as long as it is a sufficient amount for the synthesized product. However, if the amount of the organic solvent is too small, SO ₄ ^{2− and the} like may not be sufficiently dissolved. On the other hand, if it is unnecessarily large, the organic solvent is wasted and the amount of the polycyclic compound to be purified may slightly decrease (depending on the type of organic solvent and the structure of the polycyclic compound, the polycyclic compound may be reduced. May be slightly soluble in organic solvents). For these reasons, the organic solvent is preferably about 200 to 10,000 parts by mass with respect to 100 parts by mass of the composite.

After mixing with an organic solvent, the mixture is sufficiently stirred to promote dissolution of SO ₄ ^{2− and the} like.
Next, the obtained dispersion is filtered. The filtration method is preferably natural filtration using gravity, or reduced pressure filtration for reducing the lower surface of the filter medium. But the filtration method can also be performed by pressure filtration, centrifugal filtration, or the like.
As the filter medium, cellulose-based filter paper that is widely used for natural filtration and the like can be used. However, other than cellulose-based filter media, for example, filter media other than paper such as glass fiber-based filters may be used.
As the filter medium, for example, a filter medium having a pore diameter of about 0.8 μm is preferably used. By using the filter medium, SO ₄ ²⁻ and the polycyclic compound can be separated reliably and in a relatively short time.
When filter paper is used as the filter medium, the type of filter paper (mainly fineness of the eyes) is preferably, for example, 5 types C and 6 types for quantitative analysis (both comply with JIS P 3801).

The dispersion is separated into a filtrate and a residue by filtration. SO ₄ ^{2- and the} like dissolved in the organic solvent are removed as a filtrate. Polycyclic compounds that are sparingly soluble in organic solvents are removed as a residue. Therefore, SO ₄ ²⁻ etc. can be easily separated from the polycyclic compound. The polycyclic compound can be purified by drying the residue.
If necessary, the residue may be mixed with the organic solvent again and filtration may be repeated. By repeating filtration several times, a polycyclic compound with higher purity can be obtained.

In the mixing and filtration of the organic solvent (that is, purification of the polycyclic compound), the amount of residual impurities (amount of sulfuric acid, sulfate, etc.) in the polycyclic compound is 100 mg or less per 1 g of the polycyclic compound. Up to 20 mg, more preferably 20 mg or less. By reducing the amount of residual impurities to a range of 100 mg or less, SO ₄ ^{2− and the} like in the coating liquid described later can be made extremely small, and a coating liquid excellent in coating property can be prepared.

<Coating liquid containing polycyclic compound>
The high-purity polycyclic compound obtained through the above production method (purification method) can be used for appropriate applications. The use of the purified polycyclic compound is preferably a coating liquid for forming a birefringent film or a coating liquid for forming a polarizing film.
That is, the high-purity polycyclic compound obtained through the above production method (purification method) can be dissolved in an appropriate solvent to form a coating solution. The polycyclic compound is water-soluble. For this reason, water can be used as a solvent for preparing the coating liquid.
When water is used as the solvent, the electrical conductivity of water is preferably 20 μS / cm or less (lower limit is 0 μS / cm), more preferably 0.001 μS / cm to 10 μS / cm, and particularly preferably 0.8. 01 μS / cm to 5 μS / cm. This is because a birefringent film having a high in-plane birefringence can be produced by using a coating liquid having an electric conductivity of water in the above range. In addition, the said electrical conductivity can be measured by the method as described in the following Example.

In the coating liquid, one or more of the polycyclic compounds or two or more having different structures are dissolved. The concentration of the polycyclic compound in the coating liquid is not particularly limited, but is preferably 5% by mass to 35% by mass and more preferably 5% by mass because it exhibits a stable nematic liquid crystal phase in the solution. % To 30% by mass. The nematic liquid crystal phase can be confirmed and identified by the optical pattern of the liquid crystal phase observed with a polarizing microscope.
Moreover, when the pH value of the coating solution is low, it is desirable to add an alkali to adjust the pH to about 4 to 10 and further to about pH 6 to 8.

  Further, an additive may be added to the coating liquid. Examples of additives include plasticizers, heat stabilizers, light stabilizers, lubricants, antioxidants, ultraviolet absorbers, flame retardants, colorants, antistatic agents, compatibilizers, crosslinking agents, and thickeners. . The addition amount of these additives is preferably more than 0 and 10 parts by mass or less with respect to 100 parts by mass of the coating liquid.

  In addition, a surfactant may be added as an additive to the coating liquid. The surfactant is used for improving the wettability and coating property of the polycyclic compound to the substrate surface. The surfactant is preferably a nonionic surfactant. The addition amount of the surfactant is preferably more than 0 and 5 parts by mass or less with respect to 100 parts by mass of the coating liquid.

<Birefringent film and polarizing film containing polycyclic compound>
The birefringent film or polarizing film of the present invention can be obtained by forming a composition containing the polycyclic compound.
(Production method of birefringent film or polarizing film)
The birefringent film or polarizing film of the present invention can be produced, for example, by a method including the following steps (1) to (3).
(1) a step of preparing the coating liquid,
(2) a step of preparing a base material on which at least one surface is hydrophilized,
(3) A step of applying and drying the solution prepared in the step (1) on the surface of the base material prepared in the step (2) subjected to the hydrophilic treatment.
According to such a production method, a laminated film including at least a birefringent film or a polarizing film and a substrate can be obtained.
In addition, the order which implements a process (1) and a process (2) is not specifically limited, After performing a process (1) previously, you may perform a process (2) or a process (2). After performing step (1), step (1) may be performed, or step (1) and step (2) may be performed in parallel.

The preparation of the coating solution used in the step (1) is as described above.
The “hydrophilic treatment” in the above step (2) refers to a treatment for reducing the water contact angle of the substrate. The hydrophilization treatment is performed in order to improve the wettability and coatability of the substrate surface on which the polycyclic compound is coated. The hydrophilization treatment is a treatment for reducing the contact angle of water at 23 ° C. of the base material by preferably 10% or more, more preferably a treatment for reducing the contact angle of water by 15% to 80%. The treatment is preferably reduced by 20% to 70%. In addition, the ratio (%) to reduce is calculated | required by Formula; {(Contact angle before processing-Contact angle after processing) / Contact angle before processing} × 100. The contact angle is determined using a solid-liquid interface analyzer [product name “Drop Master 300” manufactured by Kyowa Interface Science Co., Ltd.] (droplet 0.5 μl, static contact angle measurement after 5 seconds from dropping). Can be measured.

  Further, the hydrophilization treatment is a treatment for reducing the contact angle of water at 23 ° C. of the substrate, preferably by 5 ° or more, and more preferably a treatment for reducing the contact angle by 10 ° to 65 °. Yes, and particularly preferably a treatment for lowering by 20 ° to 65 °.

  Further, the hydrophilization treatment is a treatment in which the contact angle of water at 23 ° C. of the substrate is preferably 5 ° to 60 °, more preferably 5 ° to 50 °, and particularly preferably. This is a treatment of 5 ° to 45 °. This is because by setting the water contact angle of the substrate within the above range, a birefringent film having a high in-plane birefringence and a small thickness variation can be obtained. Moreover, it is because the polarizing film which is excellent in a polarization characteristic and has small thickness variation is obtained by making the contact angle of the water of a base material into the said range.

  Any appropriate method can be adopted as the hydrophilic treatment. As the hydrophilic treatment, for example, a dry treatment or a wet treatment may be used. Examples of the dry treatment include discharge treatment such as corona treatment, plasma treatment, and glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, ionizing active ray treatment such as ultraviolet ray treatment, and electron beam treatment. Examples of the wet treatment include ultrasonic treatment using a solvent such as water and acetone, alkali treatment, anchor coating treatment, and the like. These treatments may be used singly or in combination of two or more.

  Preferably, the hydrophilization treatment is a corona treatment, a plasma treatment, an alkali treatment, or an anchor coat treatment. With the above hydrophilic treatment, a birefringent film or polarizing film having high orientation and small thickness variation can be obtained. The conditions for the hydrophilization treatment, such as the treatment time and strength, can be appropriately adjusted as appropriate so that the water contact angle of the substrate falls within the above range.

  The corona treatment is typically a treatment for modifying the substrate surface by passing the substrate through corona discharge. Corona discharge is generated by applying a high frequency and high voltage between a grounded dielectric roll and an insulated electrode, thereby causing the air between the electrodes to break down and ionize. The plasma treatment is typically a treatment for modifying the substrate surface by passing the substrate through low-temperature plasma. Low temperature plasma is generated by ionizing a part of gas molecules when glow discharge occurs in an inorganic gas such as a low-pressure inert gas, oxygen, or halogen gas. The above ultrasonic cleaning treatment is typically a treatment that removes contaminants on the surface of the substrate and improves the wettability of the substrate by immersing the substrate in water or an organic solvent and applying ultrasonic waves. It is. The alkali treatment is typically a treatment for modifying the substrate surface by immersing the substrate in an alkali treatment solution in which a basic substance is dissolved in water or an organic solvent. The anchor coating treatment is typically a treatment for applying an anchor coating agent to the surface of the substrate.

  The base material to which the coating liquid is applied is used for uniformly casting the coating liquid. Any appropriate substrate can be selected. Examples of the substrate include glass substrates, quartz substrates, polymer films, plastics substrates, metal plates such as aluminum and iron, ceramic substrates, and silicon wafers. The substrate is preferably a glass substrate or a polymer film.

  Any appropriate material can be selected as the glass substrate. Preferably, the glass substrate can be equivalent to a cell substrate used for a liquid crystal cell. Examples of the glass substrate include soda lime (blue plate) glass containing an alkali component, or low alkali borosilicate glass. A commercially available glass substrate may be used as it is. Examples of commercially available glass substrates include Corning Corporation glass cord: 1737, Asahi Glass Co., Ltd. glass cord: AN635, NH Techno Glass Co., Ltd. glass cord: NA-35, and the like.

As the polymer film, it is preferable to use a film having excellent visible light transmittance and excellent transparency. The light transmittance of visible light in this polymer film is preferably 80% or more, more preferably 90% or more. However, the light transmittance means a Y value obtained by correcting the visibility based on spectrum data measured with a spectrophotometer (product name: U-4100 type, manufactured by Hitachi, Ltd.) with a film thickness of 100 μm. The haze value of the polymer film is preferably 3% or less, more preferably 1% or less. However, the haze value refers to a value measured according to JIS-K7105.
Any appropriate resin can be selected as the resin for forming the polymer film. Preferably, the polymer film contains a thermoplastic resin. Examples of the thermoplastic resin include olefin resins, cycloolefin resins, vinyl chloride resins, cellulose resins, styrene resins, polymethyl methacrylate, polyvinyl acetate, vinylidene chloride resins, polyamide resins, and polyacetal resins. And carbonate resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polysulfone resins, polyether sulfone resins, polyether ether ketone resins, polyarylate resins, amide imide resins, and imide resins. The said thermoplastic resin can be used individually by 1 type or in combination of 2 or more types. Moreover, the said thermoplastic resin can also be used after performing arbitrary appropriate polymer modification | denaturation. Examples of the polymer modification include copolymerization, crosslinking, molecular terminals, and stereoregularity.

  The substrate used in the present invention is preferably a polymer film containing a cellulose resin. Such a substrate is excellent in wettability with a polycyclic compound. This is because a birefringent film having a high in-plane birefringence and a small thickness variation can be obtained by applying the coating liquid to the substrate. This is because by applying the coating liquid to the substrate, a polarizing film having excellent polarization characteristics and small thickness variation can be obtained.

  Arbitrary appropriate things can be employ | adopted for the said cellulose resin. The cellulose-based resin is preferably a cellulose organic acid ester or a cellulose mixed organic acid ester in which part or all of the hydroxyl groups of cellulose are substituted with at least one group of acetyl group, propionyl group, and butyl group. is there. Examples of the cellulose organic acid ester include cellulose acetate, cellulose propionate, and cellulose butyrate. Examples of the cellulose mixed organic acid ester include cellulose acetate propionate and cellulose acetate butyrate. The cellulose resin can be obtained by, for example, the method described in JP 2001-188128 A [0040] to [0041].

  As the base material used in the present invention, a commercially available polymer film may be used as it is. Alternatively, a film obtained by subjecting a commercially available polymer film to secondary processing such as stretching and / or shrinking may be used. Examples of commercially available polymer films containing cellulosic resins include Fuji Photo Film Co., Ltd. Fujitac Series (trade names; ZRF80S, TD80UF, TDY-80UL), Konica Minolta Opto Co., Ltd., trade names “KC8UX2M”, and the like. Can be illustrated.

  The thickness of the substrate is preferably 20 μm to 100 μm. By setting the thickness of the base material within the above range, the handling property and coating property of the base material are excellent.

In the step (3), as a method for applying the coating liquid to the surface of the substrate, a coating method using an appropriate coater can be appropriately employed. Examples of the coater include a reverse roll coater, a normal rotation roll coater, a gravure coater, a rod coater, a slot die coater, a slot orifice coater, a curtain coater, and a fountain coater. If it is the coating system using said coater, a birefringent film or a polarizing film with small thickness dispersion can be obtained.
The coating speed of the coating liquid is preferably 50 mm / second or more, more preferably 100 mm / second or more. By setting the coating speed within the above range, the coating liquid is subjected to a shearing force suitable for orienting the polycyclic compound, has a high in-plane birefringence, and has a small thickness variation. This is because a refractive film can be obtained. Further, by setting the coating speed within the above range, a polarizing film having excellent polarization characteristics and small thickness variation can be obtained.

As a method for drying the coating liquid after coating, an appropriate method can be adopted as appropriate. The drying method uses, for example, a drying means such as an air circulating constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll, or a metal belt. be able to.
The drying temperature is equal to or lower than the isotropic phase transition temperature of the coating liquid, and it is preferable that the temperature is gradually raised from a low temperature to a high temperature for drying. The drying temperature is preferably 10 ° C to 80 ° C, more preferably 20 ° C to 60 ° C. If it is said temperature range, a birefringent film with small thickness variation can be obtained.
The drying time can be appropriately selected depending on the drying temperature and the type of solvent. However, in order to obtain a birefringent film or polarizing film with small thickness variation, the drying time is, for example, 1 minute to 30 minutes, and preferably 1 minute to 10 minutes.

In addition, you may perform the following process (4) further after the said process (1)-(3).
(4) Aluminum salt, barium salt, lead salt, chromium salt, strontium salt, and compound salt having two or more amino groups in the molecule on the birefringent film or polarizing film obtained in the above step (3) Contacting with a solution containing at least one compound salt selected from the group consisting of:

  The said process (4) is performed in order to make the birefringent film or polarizing film obtained insoluble or hardly soluble with respect to water. Examples of the compound salt include aluminum chloride, barium chloride, lead chloride, chromium chloride, strontium chloride, 4,4′-tetramethyldiaminodiphenylmethane hydrochloride, 2,2′-dipyridyl hydrochloride, 4,4′-dipyridyl hydrochloride And melamine hydrochloride and tetraaminopyrimidine hydrochloride. With such a compound salt, a birefringent film or a polarizing film excellent in water resistance can be obtained.

  The concentration of the compound salt in the solution containing the compound salt is preferably 3% by mass to 40% by mass, and more preferably 5% by mass to 30% by mass. This is because a birefringent film or a polarizing film excellent in durability can be obtained by contacting with a solution containing a compound salt having a concentration in the above range.

  As a method of bringing the solution containing the compound salt into contact with the birefringent film or polarizing film obtained in the step (3), for example, a solution containing the compound salt on the surface of the birefringent film or polarizing film is used. Any method such as a coating method, a method of immersing the birefringent film or the polarizing film in a solution containing the above compound salt may be employed. When these methods are employed, the obtained birefringent film or polarizing film is preferably washed with water or an arbitrary solvent. Then, the laminated body excellent in the adhesiveness of the interface of a base material and a birefringent film or a polarizing film can be obtained by further drying.

(Characteristics of birefringent film, etc.)
In the birefringent film of the present invention containing the above polycyclic compound, the refractive index ellipsoid satisfies the relationship of nx ≧ nz> ny.
This birefringent film exhibits in-plane and / or thickness direction birefringence, and the in-plane and / or thickness direction birefringence at a wavelength of 590 nm is 1 × 10 ⁻⁴ or more.
However, “nx ≧ nz> ny” represents the optical anisotropy of the birefringent film. nx is the refractive index in the direction that maximizes the refractive index in the plane of the birefringent film (that is, the slow axis direction), and ny is the direction that is orthogonal to the slow axis direction in the plane (that is, the fast phase). (Axial direction) and nz represents the refractive index in the thickness direction (hereinafter the same).

  The polycyclic compound used as a material for forming the birefringent film of the present invention is preferably a compound having two or more aromatic rings and / or heterocyclic rings in the molecular structure, and more preferably aromatic rings and / or Or it is a compound which has 3-8 heterocycles, Especially preferably, it is a compound which has 4-6 aromatic rings and / or heterocycles. More specifically, it is a polycyclic compound represented by the above general formula (I) or (II). If a coating liquid containing such a polycyclic compound is used, a transparent birefringent film having no or little absorption in the visible light region can be formed.

Since the birefringent film can be formed by coating, it can be formed thin. Further, the birefringent film has a refractive index ellipsoid satisfying the relationship of nx ≧ nz> ny (nx>nz> ny or nx = nz> ny) and exhibits a high in-plane birefringence. For this reason, the birefringent film can obtain a desired retardation value with a remarkably thin thickness as compared with the conventional birefringent film. In the present specification, “nx = nz” includes not only the case where nx and nz are completely the same, but also the case where they are substantially the same. When nx and nz are substantially the same, for example, Rth [590] includes −10 nm to 10 nm.
According to the estimations of the present inventors, the reason why the birefringent film of the present invention exhibits high birefringence is that the polycyclic compound containing the —SO ₃ M group forms an aggregate in a solution. It is considered that the film formed from such a solution also exhibits high orientation because of the high order in the state in which the aggregate is formed. In particular, a polycyclic compound having a —SO ₃ M group and a —COOM group is considered to exhibit high orientation.

The transmittance of the birefringent film at a wavelength of 590 nm is preferably 85% or more, more preferably 90% or more.
The in-plane retardation value (Re [590]) at a wavelength of 590 nm of the birefringent film can be set to an appropriate value according to the purpose. The Re [590] is 10 nm or more, preferably 20 nm to 1000 nm, more preferably 50 nm to 500 nm, and particularly preferably 100 nm to 400 nm. In this specification, the in-plane retardation value (Re [λ]) refers to an in-plane retardation value at a wavelength λ (nm) at 23 ° C. Re [λ] can be obtained by the formula: Re [λ] = (nx−ny) × d, where d (nm) is the thickness of the birefringent film.

  Rth [590] of the birefringent film can be set to an appropriate value as long as the refractive index ellipsoid satisfies the relationship of nx ≧ nz> ny. The difference between the in-plane retardation value (Re [590]) and the thickness direction retardation value (Rth [590]) of the birefringent film at a wavelength of 590 nm is preferably 10 nm to 800 nm, more preferably It is 10 nm-400 nm, Most preferably, it is 10 nm-200 nm. In this specification, the thickness direction retardation value (Rth [λ]) refers to the thickness direction retardation value at 23 ° C. and the wavelength λ (nm). Rth [λ] can be obtained by the formula: Rth [λ] = (nx−nz) × d, where d (nm) is the thickness of the film.

  The Nz coefficient of the birefringent film is preferably more than 0 and less than 1, more preferably 0.1 to 0.8, particularly preferably 0.1 to 0.7, and most preferably 0. .1 to 0.6. If the Nz coefficient is in the above range, the birefringent film of the present invention can be used for optical compensation of liquid crystal cells in various drive modes. In this specification, the Nz coefficient is a value calculated from Rth [590] / Re [590].

  The in-plane birefringence (Δn [590] = nx−ny) of the birefringent film of the present invention at a wavelength of 590 nm is preferably 0.05 or more, more preferably 0.1 to 0.5. Especially preferably, it is 0.2-0.4. Note that Δn [590] can be appropriately adjusted within the above range depending on the molecular structure of the polycyclic compound.

  The thickness of the birefringent film is preferably 0.05 μm to 10 μm, more preferably 0.1 μm to 8 μm, and particularly preferably 0.1 μm to 6 μm. By setting the thickness within the above range, for example, when used in a liquid crystal display device, a range of retardation values useful for improving display characteristics can be obtained.

(Properties of polarizing film)
The polarizing film of the present invention containing the polycyclic compound preferably has a degree of polarization of 90% or more, more preferably 95% or more. The single transmittance of the polarizing film is preferably 35% or more, more preferably 40% or more. However, the single transmittance and the degree of polarization are values based on a wavelength of 550 nm at 23 ° C. The reason why a polarizing film having such polarizing properties can be obtained is considered to be that the polycyclic compound exhibits high orientation by applying a coating solution.

The polycyclic compound used as the material for forming the polarizing film of the present invention is a compound having a maximum value of a light absorption spectrum in a wavelength range of 400 nm to 800 nm. The polycyclic compound is preferably a compound having a maximum value of a light absorption spectrum in a wavelength range of 400 nm to 800 nm and having two or more aromatic rings and / or hetero rings in the molecular structure. More preferred are compounds having the same maximum value and 3 to 8 aromatic rings and / or heterocyclic rings, and particularly preferred are polycyclic compounds having a perylene skeleton. More specifically, it is a polycyclic compound represented by the above general formula (III) or (IV). If a coating liquid containing such a polycyclic compound is used, a polarizing film having excellent dichroism can be formed.
The thickness of the polarizing film is preferably 0.05 μm to 10 μm, more preferably 0.1 μm to 5 μm. Since the polarizing film of the present invention can be formed by coating, it can be formed thin.

<Use of birefringent film or polarizing film>
The use of the birefringent film of the present invention is not particularly limited. Typically, λ / 4 plate for liquid crystal display device, λ / 2 plate, viewing angle widening film, antireflection film for flat panel display, etc. Is mentioned. The birefringent film can also be used for image display devices such as organic EL display devices. In one embodiment, the birefringent film may be laminated with a polarizing film and used as a polarizing plate. Hereinafter, this polarizing plate will be described.

  The polarizing plate of this invention is equipped with the said birefringent film and a polarizing film at least. This polarizing plate may contain the laminated film provided with a base material and a birefringent film at least, and may contain the other birefringent film and arbitrary protective layers. Practically, any appropriate adhesive layer is provided between the constituent layers of the polarizing plate, and the birefringent film and the constituent members are attached.

  As the polarizing film constituting the polarizing plate, an appropriate film may be adopted as long as it converts natural light or polarized light into linearly polarized light. As the polarizing film, a polarizing film containing the polycyclic compound may be used, or another polarizing film may be used. The other polarizing film is preferably a stretched film mainly composed of a polyvinyl alcohol resin containing iodine or a dichroic dye. The thickness of the polarizing film comprised from this stretched film is usually 5 μm to 50 μm.

  Any appropriate adhesive layer can be selected as long as it joins the surfaces of adjacent members and integrates them with practically sufficient adhesive force and adhesion time. Examples of the material for forming the adhesive layer include an adhesive, a pressure-sensitive adhesive, and an anchor coating agent. The adhesive layer may have a multilayer structure in which an anchor coat agent layer is formed on the surface of the adherend, and an adhesive layer or a pressure-sensitive adhesive layer is formed on the anchor coat agent layer. It may be a thin layer (also called a hairline). The adhesive layer disposed on one side of the polarizing film and the adhesive layer disposed on the other side may be the same or different.

  The angle at which the polarizing film and the birefringent film are bonded to each other can be appropriately set according to the purpose. For example, when the polarizing plate is used as an antireflection film, the angle formed by the absorption axis direction of the polarizing film and the slow axis direction of the birefringent film is preferably 25 ° to 65 °, More preferably, it is 35 ° to 55 °. When used as a viewing angle widening film, in the polarizing plate, an angle formed by the absorption axis direction of the polarizing film and the slow axis direction of the birefringent film is substantially parallel or substantially orthogonal. . In this specification, “substantially parallel” includes a range of 0 ° ± 10 °, preferably 0 °, between the absorption axis direction of the polarizing film and the slow axis direction of the birefringent film. ± 5 °. “Substantially orthogonal” means that the angle formed between the absorption axis direction of the polarizing film and the slow axis direction of the birefringent film includes a range of 90 ° ± 10 °, preferably 90 ° ± 5 °. is there.

  The application of the polarizing film of the present invention is not particularly limited, but is typically an optical application of a liquid crystal display device. Since the polarizing film of this invention is formed by applying to a base material, this base material can also be utilized as a protective film.

The present invention will be further described using the following examples and comparative examples. In addition, this invention is not limited only to these Examples. A part of each analysis method used in the examples is as follows.
(1) Measuring method of thickness:
A part of the coating film formed on the surface of the substrate (glass plate) is peeled off, and the step between the substrate and the coating film is measured with a three-dimensional non-contact surface shape measurement system [manufactured by Ryoka System Co., Ltd. The name “Micromap MM5200”] was used as the thickness.
(2) Refractive index measurement method:
Measurement was performed at 23 ° C. using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. In addition, the value measured using the Abbe refractometer [Atago Co., Ltd. product name "DR-M4"] was used for the average refractive index.
(3) Measuring method of single transmittance and degree of polarization:
Using a spectrophotometer [Murakami Color Research Laboratory Co., Ltd., product name “DOT-3”], the measurement was performed at 23 ° C. The measured values of the degree of polarization and single transmittance were based on a wavelength of 550 nm.
The single transmittance is a Y value of tristimulus values based on the 2-degree field of JlS Z 8701-1995.
The degree of polarization is measured by measuring parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ), and the formula: degree of polarization (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 It can be obtained from x100. The parallel transmittance (H ₀ ) is a value of transmittance of a parallel laminate prepared by superposing two polarizing films to be measured so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminate prepared by superposing two polarizing films to be measured so that their absorption axes are orthogonal to each other. In addition, these transmittance | permeability is Y value which performed visibility correction | amendment by the 2 degree visual field (C light source) of JlS Z 8701-1982.

[Synthesis Example 1]
To a reaction vessel equipped with a stirrer, 5 liters of glacial acetic acid and 490 g of purified acenaphthenequinone were added and stirred for 15 minutes under nitrogen bubbling to obtain an acenaphthenequinone solution. Similarly, 7.5 liters of glacial acetic acid and 275 g of o-phenylenediamine were added to another reaction vessel equipped with a stirrer and stirred for 15 minutes under nitrogen bubbling to obtain an o-phenylenediamine solution. Thereafter, the o-phenylenediamine solution was gradually added to the acenaphthenequinone solution over 1 hour while stirring in a nitrogen atmosphere, and then the reaction was continued by continuing stirring for 3 hours. After adding ion exchange water to the obtained reaction liquid, the precipitate was filtered to obtain a crude product containing acenaphtho [1,2-b] quinoxaline. This crude product was purified by recrystallization from hot glacial acetic acid.

  Next, as shown in the following reaction route (c), 300 g of the above acenaphtho [1,2-b] quinoxaline was added to 30% fuming sulfuric acid (2.1 liters) and stirred at room temperature for 24 hours. The mixture was stirred and reacted for 32 hours. While maintaining the obtained solution at 40 ° C. to 50 ° C., 4.5 liters of ion exchange water was added for dilution, and the mixture was further stirred for 3 hours. The precipitate was filtered and recrystallized with sulfuric acid to synthesize acenaphtho [1,2-b] quinoxaline-2,5-disulfonic acid (hereinafter referred to as 2,5-disulfo-QAN).

[Example 1-1]
2 g of a wet cake product of the synthesized product (2,5-disulfo-QAN containing residual sulfuric acid) obtained in Synthesis Example 1 above was placed in 10 g of methanol and sufficiently stirred to obtain a dispersion. This dispersion was filtered under reduced pressure using filter paper (trade name: NO.5C, manufactured by Advantech Co., Ltd.) to obtain a residue. This residue was again mixed with 10 g of methanol and subjected to the same filtration. Mixing and filtration of 10 g of methanol were repeated 4 times in total. The residue obtained by final filtration was taken out and vacuum-dried at 60 ° C. for 6 hours to obtain a solid content.

[Example 1-2]
Filtration was performed in the same manner as in Example 1-1 except that 10 g of acetone was used instead of methanol to obtain a solid.

[Comparative Example 1-1]
Filtration was performed in the same manner as in Example 1-1 except that 10 g of toluene was used instead of methanol to obtain a solid.

[Comparative Example 1-2]
Filtration was performed in the same manner as in Example 1-1 except that 10 g of cyclohexane was used instead of methanol to obtain a solid.

[Comparative Example 1-3]
1.3 kg of wet cake product of the synthesized product (2,5-disulfo-QAN containing residual sulfuric acid) obtained in Synthesis Example 1 was 48.7 liters of ion-exchanged water (electric conductivity: 0.1 μS / cm). Further, 9.8 liters of a 5% by mass aqueous solution of sodium hydroxide was added to neutralize the solution. The obtained aqueous solution is put in a supply tank, and the amount of liquid becomes constant using a high pressure RO element test apparatus equipped with a reverse osmosis membrane filter (manufactured by Nitto Denko Corporation, trade name: NTR-7430 filter element). As described above, circulation filtration was performed while adding reverse osmosis water. Then, the residual sulfuric acid or its sulfate was removed until the electrical conductivity of the waste liquid reached 13.6 μS / cm to obtain a purified aqueous solution.

[Synthesis Example 2]
In the same manner as in Synthesis Example 1, acenaphtho [1,2-b] quinoxaline was obtained.
Next, as shown in the following reaction route (d), 300 g of the above acenaphtho [1,2-b] quinoxaline was added to 30% fuming sulfuric acid (2.1 liters) and stirred at room temperature for 48 hours to be reacted. It was. While maintaining the obtained solution at 40 ° C. to 50 ° C., 4.5 liters of ion exchange water was added for dilution, and the mixture was further stirred for 3 hours. The precipitate was filtered to synthesize acenaphtho [1,2-b] quinoxaline-2-sulfonic acid (hereinafter referred to as 2-sulfo-QAN).

[Example 2-1]
2 g of a wet cake product of the synthesized product (2-sulfo-QAN containing residual sulfuric acid) obtained in Synthesis Example 2 above was placed in 10 g of methanol and sufficiently stirred to obtain a dispersion. In the same manner as in Example 1-1, mixing and filtration were performed 4 times in total to obtain a solid.

[Example 2-2]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of acetone was used instead of methanol to obtain a solid.

[Example 2-3]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of isopropyl alcohol was used instead of methanol to obtain a solid.

[Comparative Example 2-1]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of toluene was used instead of methanol to obtain a solid.

[Comparative Example 2-2]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of cyclohexane was used instead of methanol to obtain a solid.

[Comparative Example 2-3]
500 g of the wet cake product of the synthesized product (2-sulfo-QAN containing residual sulfuric acid) obtained in Synthesis Example 2 was dissolved in 35.5 liters of ion-exchanged water (electric conductivity: 0.1 μS / cm), Furthermore, 3.5 liters of 5 mass% aqueous solution of sodium hydroxide was added and neutralized. The obtained aqueous solution is put in a supply tank, and the amount of liquid becomes constant using a high pressure RO element test apparatus equipped with a reverse osmosis membrane filter (manufactured by Nitto Denko Corporation, trade name: NTR-7430 filter element). As described above, circulation filtration was performed while adding reverse osmosis water. Then, residual sulfuric acid or its sulfate was removed until the electrical conductivity of the waste liquid reached 8.06 μS / cm to obtain a purified aqueous solution.

[Synthesis Example 3]
<Sulfonation of dibenzimidazole derivative of perylenetetracarboxylic acid>
Into a reaction vessel equipped with a stirrer, 30% fuming sulfuric acid (0.5 liter) was added, and 100 g of dibenzimidazole derivative of perylenetetracarboxylic acid (hereinafter referred to as PCDI) was gradually added while stirring at 35 ° C. Went. Thereafter, 4.5 liters of ion exchange water was added for dilution, and the reaction was terminated. The precipitate was filtered and recrystallized with sulfuric acid to obtain a PCDI sulfonated product (see reaction formula (e)).
The PCDI used was a mixture of a cis type and a transformer type as shown in the equation (e).
A 0.1 mmol / L aqueous solution of this PCDI sulfonated product was prepared, and a light absorption spectrum was measured using a spectrophotometer (manufactured by Hitachi, Ltd., product name: “U-4100 spectrophotometer”). Maximum absorption was shown.

[Example 3-1]
2 g of a wet cake product of the synthesized product (PCDI sulfonated product containing residual sulfuric acid) obtained in Synthesis Example 3 was placed in 10 g of methanol and sufficiently stirred to obtain a dispersion. This dispersion was filtered under reduced pressure using filter paper (trade name: NO.5C, manufactured by Advantech Co., Ltd.) to obtain a residue (solid content). This residue was again mixed with 10 g of methanol and subjected to the same vacuum filtration. Mixing and filtration of 10 g of methanol were repeated 4 times in total. The residue obtained by final filtration was taken out and vacuum-dried at 60 ° C. for 6 hours to obtain a final solid content.

[Example 3-2]
Filtration was performed in the same manner as in Example 3-1 except that 10 g of acetone was used instead of methanol to obtain a solid.

[Example 3-3]
Filtration was performed in the same manner as in Example 3-1 except that 10 g of isopropyl alcohol was used instead of methanol to obtain a solid.

[Comparative Example 3-1]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of toluene was used instead of methanol to obtain a solid.

[Comparative Example 3-2]
Filtration was performed in the same manner as in Example 2-1 except that 10 g of cyclohexane was used instead of methanol to obtain a solid.

  In order to evaluate the amount of residual sulfuric acid in the solid matter obtained in Examples 1-1 to 3-3 and the aqueous solution obtained in Comparative Examples 1-1 to 2-3, neutralization titration and electrical conductivity measurement were performed. It was.

(Neutralization titration)
Evaluation of the residual sulfuric acid amount by neutralization titration is as follows. The solid material obtained in each of the above Examples and Comparative Examples was dissolved in ion-exchanged water to prepare a 0.1% by mass aqueous solution. 75 g of this aqueous solution was subjected to neutralization titration using a 0.1% by mass aqueous solution of sodium hydroxide so that pH = 7.
The amount of residual sulfuric acid was determined according to the following formula.
Residual sulfuric acid amount (mg) / raw material solid content (g) = [{(base amount in sodium hydroxide aqueous solution used for titration (mol) −when all of the raw material solid content used for titration is assumed to be the target quinoxaline) Acid amount (mol) × 98.03} / 2] × (1000 / raw material solids (g)).
However, for Comparative Examples 1-3 and 2-3, neutralized titration was not possible because a neutralized purified aqueous solution was obtained.
For reference, the amount of residual sulfuric acid of the synthesized products (before filtration treatment) synthesized in Synthesis Examples 1 to 3 was also measured in the same manner as described above.

(Electrical conductivity)
The electrical conductivity (μS / cm) was measured using a solution conductivity meter (product name: CM-117, manufactured by Kyoto Electronics Industry Co., Ltd.). An aqueous solution for measurement was prepared as follows. The solid material obtained in each Example and Comparative Example was dissolved in ion-exchanged water to prepare a 0.1% by mass aqueous solution. An aqueous solution for measurement was obtained by neutralizing the aqueous solution to pH = 7 while adding a 0.1% by mass aqueous sodium hydroxide solution.
Moreover, about Comparative Example 1-3 and Comparative Example 2-3, the aqueous solution for a measurement was obtained by adding and diluting the obtained refined aqueous solution so that it might become the same concentration as the above.
As a reference, for the electrical conductivity of the composite synthesized in a total Narurei 1 Synthesis Example 3 (filtration pretreatment), it was measured in the same method as that described above.

  Table 1 shows the measurement results of the amount of residual sulfuric acid and electrical conductivity. As shown in Table 1, the solids obtained in each Example were able to remove a large amount of sulfuric acid and purified a high-purity polycyclic compound compared to before the treatment.

[Example 4]
The solid matter obtained in Example 1-2 (1.56 g) and the solid matter obtained in Example 2-2 (0.84 g) were added to 50 ml of ion-exchanged water (electric conductivity: 1.7 μS / cm). It melt | dissolved and further neutralized so that it might become pH = 6.9 by adding ammonium hydroxide. The obtained aqueous solution was prepared using a rotary evaporator so that the concentration of the polycyclic compound in the aqueous solution was 24% by mass. When the aqueous solution obtained here was observed with a polarizing microscope, it exhibited a nematic liquid crystal phase at 23 ° C.
Next, the above aqueous solution is applied to a glass plate having a thickness of 1.3 mm (manufactured by Matsunami Glass Industrial Co., Ltd., trade name: MATSUNAMI SLIDE GLASS) using a bar coater [manufactured by BUSCHMAN, trade name “mayer rot HS1.5”]. And dried naturally in a constant temperature room at 23 ° C. When the surface of the coating film was observed visually, it was uniformly coated without repellency.
The coating film thus formed has a refractive index ellipsoid satisfying the relationship of nx>nz> ny and can be used as a birefringent film. The coated film had a thickness of 0.6 μm, Re [590] = 203 nm, and Nz coefficient = 0.25.

[Comparative Example 4]
Except that 1.56 g of the composite obtained in Synthesis Example 1 (before filtration treatment) and 0.84 g of the synthesis product obtained in Synthesis Example 1 (before filtration treatment) were used, the same as Example 3 was used. An aqueous solution was prepared and applied to form a coating film on a glass plate.
When the surface of the obtained coating film was visually observed, many circular cissing marks having a diameter of 0.5 mm or more were generated.

[Example 5]
2.0 g of the solid material (PCDI sulfonated product) obtained in Example 3-2 was dissolved in 50 ml of ion-exchanged water (electric conductivity: 1.7 μS / cm), and further 5% by mass of hydroxide. Aqueous sodium solution was added to neutralize to pH = 4.58. The obtained aqueous solution was concentrated using a rotary evaporator until the concentration of the PCDI sulfonated product in the aqueous solution became 11% by mass. When the obtained aqueous solution was observed with a polarizing microscope, a nematic liquid crystal phase was exhibited at 23 ° C.
Next, the above aqueous solution is applied to a glass plate having a thickness of 1.3 mm (manufactured by Matsunami Glass Industrial Co., Ltd., trade name: MATSUNAMI SLIDE GLASS) using a bar coater [manufactured by BUSCHMAN, trade name “mayer rot HS1.5”]. And dried naturally in a constant temperature room at 23 ° C. When the surface of the coating film was observed visually, it was uniformly coated without repellency.
The coating film thus formed can be used as a polarizing film. The coated film had a thickness of 0.35 μm, a degree of polarization = 95%, and a single transmittance = 43%.

[Comparative Example 5]
An aqueous solution was prepared in the same manner as in Example 5 except that 2.0 g of the synthesized product (before filtration) obtained in Synthesis Example 3 was used, and this was applied to form a coating film on a glass plate. Formed.
When the surface of the obtained coating film was visually observed, many circular cissing marks having a diameter of 0.3 mm or more were generated. Such a perforated membrane cannot be used as a film.

Claims (18)

A mixture containing an impurity containing at least one of SO ₄ ²⁻ and SO ₃ ⁻ and a polycyclic compound having a —SO ₃ M group (where M represents a counter ion) is used as SO ₄ ²⁻ or SO ₃ ^-, characterized in that the dissolved and wherein the step of polycyclic compound to obtain a dispersion by mixing the sparingly soluble organic solvent, and filtering the dispersion, a step, of separating the polycyclic compound And a method for purifying a polycyclic compound.   The method for purifying a polycyclic compound according to claim 1, wherein the organic solvent is at least one selected from methanol, ethanol, isopropyl alcohol, other lower alcohols, and acetone. The method for purifying a polycyclic compound according to claim 1 or 2, wherein the polycyclic compound comprises a quinoxaline derivative represented by the following general formula (I).

In formula (I), M represents a counter ion. A and B represent a substituent, and a and b represent the number of substitutions (a is an integer of 0 to 4, and b is an integer of 0 to 6). L and m represent the number of substitutions (l is an integer of 0 to 4, and m is an integer of 0 to 6). However, l and m are not 0 at the same time. The method for purifying a polycyclic compound according to claim 3, wherein the polycyclic compound comprises a quinoxaline derivative represented by the following general formula (II).

In formula (II), M represents a counter ion. m represents the number of substitutions (an integer of 1 to 6).   The method for purifying a polycyclic compound according to claim 1 or 2, wherein the polycyclic compound has a maximum value of a light absorption spectrum at a wavelength of 400 nm to 800 nm. The method for purifying a polycyclic compound according to claim 5, wherein the polycyclic compound comprises a perylene derivative represented by the following general formula (III) or general formula (IV).

In formula (III) and formula (IV), M represents a counter ion. n1-n4 represents a substituent (integer of 0-4). However, all of n1 to n4 are not 0 at the same time.   The method for purifying a polycyclic compound according to any one of claims 1 to 6, wherein the amount of residual impurities in the polycyclic compound after separation is 100 mg / g or less. A step of sulfonation to synthesize a polycyclic compound having a —SO ₃ M group (where M represents a counter ion) to obtain a compound;
Mixing the composite with an organic solvent in which SO ₄ ²⁻ or SO ₃ ⁻ is dissolved and the polycyclic compound is hardly soluble, to obtain a dispersion;
Separating a polycyclic compound having a -SO 3 _M group by filtering the dispersion,
The manufacturing method of the polycyclic compound which has this.   The method for producing a polycyclic compound according to claim 8, wherein at least one selected from sulfuric acid, fuming sulfuric acid, and inorganic sulfonic acid is used as the sulfonation treatment. The method for producing a polycyclic compound according to claim 8 or 9, wherein the polycyclic compound comprises a quinoxaline derivative represented by the following general formula (I).

In formula (I), M represents a counter ion. A and B represent a substituent, and a and b represent the number of substitutions (a is an integer of 0 to 4, and b is an integer of 0 to 6). L and m represent the number of substitutions (l is an integer of 0 to 4, and m is an integer of 0 to 6). However, l and m are not 0 at the same time.   The method for producing a polycyclic compound according to claim 8 or 9, wherein the polycyclic compound has a maximum value of a light absorption spectrum at a wavelength of 400 nm to 800 nm.   The method for producing a polycyclic compound according to any one of claims 8 to 11, wherein the polycyclic compound is soluble in water.   The coating which shows the liquid crystal phase obtained by dissolving the polycyclic compound isolate | separated by the purification method in any one of Claims 1-4, or the manufacturing method in any one of Claims 8-10 in water. liquid.   The coating liquid which shows the liquid crystal phase obtained by dissolving the polycyclic compound isolate | separated by the purification method of Claim 5 or 6, or the manufacturing method of Claim 11 in water.   The coating liquid according to claim 13 or 14, wherein the liquid crystal phase is a nematic liquid crystal phase.   The coating liquid according to claims 13 to 15, wherein the pH is adjusted to 4 to 10.   A birefringent film satisfying a relationship of nx ≧ nz> ny obtained by coating the coating liquid according to claim 13 on a substrate and drying.   The polarizing film obtained by apply | coating the coating liquid of Claim 14 on a base material, and drying.