JP5133812B2 - Polarizing film, coating liquid, and manufacturing method of polarizing film - Google Patents

Description

  The present invention relates to a polarizing film containing a disazo compound and excellent in transparency, a coating liquid containing a disazo compound, and the like.

The polarizing film is an optical film having a function of transmitting specific linearly polarized light from polarized light or natural light. The polarizing film is used, for example, as a constituent member of a liquid crystal display device or a lens of polarized sunglasses.
A general-purpose polarizing film can be obtained, for example, by stretching a polyvinyl alcohol film dyed with iodine.
A polarizing film obtained by a solution casting method of a solution containing a disazo compound is also known.
This polarizing film is obtained by applying a solution containing a disazo compound having a benzene ring on a substrate and drying it (for example, Patent Document 1).
JP 2007-126628 A

The polarizing film containing the disazo compound has excellent heat resistance and high dichroism. Furthermore, since the polarizing film containing the disazo compound can be formed by a solution casting method, it is much thinner than a polarizing film made of a polyvinyl alcohol film dyed with iodine.
However, since the polarizing film containing the disazo compound described in the above publication has insufficient transparency, there is a demand for its improvement.

A first object of the present invention is to provide a polarizing film containing a disazo compound and having excellent transparency.
The second object of the present invention is to provide a coating liquid that can form a polarizing film containing a disazo compound and having excellent transparency, and a method for producing a polarizing film using the coating liquid .

  The present inventors diligently studied the reason why the conventional polarizing film containing a disazo compound has insufficient transparency. As a result, the present inventors have found that the cause is that the conventional disazo compound exists as fine crystals in the polarizing film. When such fine crystals are present in the polarizing film, haze (light scattering) of the polarizing film is increased, and the transparency of the polarizing film is deteriorated.

  Therefore, the present invention provides a polarizing film containing a disazo compound represented by the following general formula (I).

In the general formula (I), Q ₁ represents an aryl group which may have a substituent, Q ₂ represents an arylene group which may have a substituent, and M represents a counter ion. , X is a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms (non-adjacent carbon atom in the alkyl group may be replaced by an oxygen atom), methacryl group, or acryl group M represents an integer of 1 or 2, and n represents an integer of 1 to 4.

In the disazo compound represented by the general formula (I), a hydroxyalkyl group having an OH group, a SO ₃ M group, and OX is bonded to a naphthyl group. For this reason, the disazo compound of this invention is excellent in the solubility with respect to aqueous solvents, such as water.
Such a disazo compound is unlikely to become a fine crystal in the polarizing film. Therefore, the polarizing film of the present invention has a low haze value and is excellent in transparency.

According to another aspect of the present invention, a coating liquid for forming a polarizing film is provided.
The coating liquid of this invention is a coating liquid for polarizing film formation , Comprising: The disazo compound represented by the said general formula (I), and a solvent are included.

According to another aspect of the present invention, a method for producing a polarizing film is provided.
In the method for producing a polarizing film of the present invention, the polarizing film is formed by applying the coating liquid onto a substrate and drying it.

The polarizing film of the present invention has a small haze value and excellent transparency.
Moreover, the coating liquid of this invention can form the polarizing film excellent in transparency by apply | coating and drying this on a base material .

(Polarizing film and disazo compound of the present invention)
The polarizing film of the present invention contains a disazo compound represented by the following general formula (I). The disazo compound of the present invention is represented by the general formula (I).
In the present specification, “Y to Z” means “Y or more and Z or less”.

In the general formula (I), Q ₁ represents an aryl group which may have a substituent, Q ₂ represents an arylene group which may have a substituent, and M represents a counter ion. , X is a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms (non-adjacent carbon atom in the alkyl group may be replaced by an oxygen atom), methacryl group, or acryl group M represents an integer of 1 or 2, and n represents an integer of 1 to 4.

M in the general formula (I) is preferably 1. Moreover, n of general formula (I) becomes like this. Preferably it is an integer of 1-3, More preferably, it is 1 or 2.
When the alkyl group represented by X has 2 or more carbon atoms, non-adjacent carbon atoms in the alkyl group may be replaced with oxygen atoms. The alkyl group may be linear or branched, but is preferably linear. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a pentyl group, an isopentyl group, and a hexyl group. The number of carbon atoms of the alkyl group is preferably 1-12, more preferably 2-8.

When the alkyl group having 1 to 18 carbon atoms has a substituent, examples of the substituent include a —OM group, a —SO ₃ M group, a —COOM group, a phenyl group, a halogen group such as fluorine, a glycidyl group, and an amino group. And nitro group. The alkyl group may have at least one selected from these substituents. Said M represents a counter ion similarly to general formula (I).

  Preferably, X in the general formula (I) is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms having one or more hydroxyl groups (non-adjacent carbon atoms in the alkyl group may be replaced by oxygen atoms), And a methacryl group. Carbon number of the alkyl group having one or more hydroxyl groups is preferably 1-12, more preferably 2-8.

M in the general formula (I) is preferably a hydrogen atom; an alkali metal atom such as Li, Na, K, or Cs; an alkaline earth metal atom such as Ca, Sr, or Ba; a metal ion; A salt of ammonium which may be substituted with a group or a hydroxyalkyl group; a salt of an organic amine and the like. Examples of metal ions 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⁺ . Examples of the organic amine include an alkylamine having 1 to 6 carbon atoms, an alkylamine having 1 to 6 carbon atoms having a hydroxyl group, and an alkylamine having 1 to 6 carbon atoms having a carboxyl group. The counter ions represented by M may be used alone or in combination of two or more.

The bonding position of the naphthyl group of the general formula (I) (the naphthyl group represented on the right side in the formula (I)) and the azo group (—N═N—) is not particularly limited. Preferably, the naphthyl group and the azo group are bonded at the 1-position or 2-position of the naphthyl group.
Specific examples of the naphthyl group of the general formula (I) include the following formulas (a) to (i).
In addition, Formula (a) thru | or Formula (c) represents the naphthyl group couple | bonded with an azo group in 1-position, and Formula (d) thru | or Formula (i) represent the naphthyl group couple | bonded with an azo group in 2-position.

  The naphthyl group of general formula (I) is preferably one represented by formula (c) or formula (d). The disazo compound having such a naphthyl group is represented by the following general formula (II) or general formula (III).

In the general formula (II) and general formula (III), Q ₁ , Q ₂ , M and X are the same as those in the general formula (I).

In the above general formulas, examples of the aryl group represented by Q ₁ include a phenyl group and a condensed ring group in which two or more benzene rings are condensed, such as a naphthyl group.
In each general formula, the arylene group represented by Q ₂ includes a condensed ring group in which two or more benzene rings are condensed, such as a naphthylene group, in addition to a phenylene group.

The aryl group or arylene group represented by Q ₁ or Q ₂ may have a substituent, or may not have a substituent. Whether the aryl group or arylene group is substituted or unsubstituted, the solvent solubility of the disazo compound is hardly changed. For this reason, the polarizing film containing the disazo compound of the present invention has a sufficiently small haze value.

When the aryl group or arylene group has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a dihydroxypropyl group. hydroxyalkyl group, an alkylamino group having 1 to 6 carbon atoms, phenylamino group having 6 to 20 carbon atoms, acylamino group having 1 to 6 carbon atoms, a halogeno group, a nitro group, a cyano group, an amino group, -SO ₃ M group , -COOM group, or -OM group. Preferably, the substituent is an alkoxy group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, an amino group, a nitro group, a halogeno group, a —OM group, a —COOM group, and a —SO ₃ M group. It is one chosen from. However, M represents a counter ion similarly to general formula (I). A disazo compound having such a substituent is excellent in solvent solubility. One or more of these substituents may be substituted. Moreover, the substituent may be substituted by arbitrary ratios.

Preferably, Q _{1 in} each general formula is a phenyl group which may have a substituent.
Preferably, Q _{2 in} each general formula is a naphthylene group which may have a substituent, and more preferably a 1,4-naphthylene group which may have a substituent.

The disazo compound in which Q _{1 in the} general formula (I) is an optionally substituted phenyl group and Q ₂ is an optionally substituted 1,4-naphthylene group has the following general formula: (IV) to (VI).

  In the general formula (V) and the general formula (VI), X, M, m and n are the same as those in the general formula (I).

In General Formula (V) and General Formula (VI), A and B are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. hydroxyalkyl group, an alkylamino group having 1 to 6 carbon atoms, phenylamino group having 6 to 20 carbon atoms, acylamino group having 1 to 6 carbon atoms, a halogeno group, a nitro group, a cyano group, an amino group, -SO ₃ M group , -COOM group, or -OM group. Said M represents a counter ion similarly to general formula (I).
The number of substitutions of A and B in the general formula (V) and the general formula (VI) is 0 to 5, preferably 1 to 2. When the number of substitutions of A is 2 or more, A may be the same or different. When the number of substitutions of B is 2 or more, B may be the same or different.

Moreover, the disazo compound represented by each said general formula is compoundable with the following method, for example.
An aniline derivative and a naphthylamine derivative are diazotized and coupled to obtain a monoazo compound. After diazotizing this monoazo compound, it is further subjected to a coupling reaction with a hydroxy naphthylamine sulfonic acid derivative to obtain a disazo compound. This disazo compound can be synthesized according to a conventionally known method (for example, Yutaka Hosoda, “Theoretical Manufacturing Dye Chemistry (5th edition)”, published by Gihodo on July 15, 1968).
Next, the disazo compound represented by the general formulas (I) to (VI) can be synthesized by N-alkylating the amino group of the naphthylamine skeleton of the disazo compound and the glycidyl compound.

  Examples of the glycidyl compound include glycidol, allyl glycidyl ether, alkyl glycidyl ether, glycerol diglycidyl ether, glycidyl methacrylate, glycidyl acrylate, (perfluoroalkylethyl) glycidyl ether, neopentyl glycol diglycidyl ether, and polypropylene glycol diglycidyl ether. , Denacol EX glycidyl compound ("Denacol EX" is a trade name of Nagase ChemteX Corporation) and the like.

  The N-alkylation reaction between the naphthylamine skeleton of the disazo compound and the glycidyl compound proceeds even without catalyst. However, the N-alkylation reaction is preferably performed in the presence of an acid catalyst such as an inorganic acid or an organic acid, or a catalyst such as a base catalyst.

  The N-alkylation reaction is usually performed in a solvent. The said solvent will not be specifically limited if the said glycidyl compound etc. can melt | dissolve. As the solvent, an aqueous solvent is preferably used. The aqueous solvent includes water, a hydrophilic solvent, and a mixed solvent of water and a hydrophilic solvent. The hydrophilic solvent is a solvent that can be dissolved substantially uniformly with water. Examples of the hydrophilic solvent include alcohols such as methanol, ethanol, ethyl alcohol, methyl alcohol and isopropyl alcohol; glycols such as ethylene glycol and diethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone and methylethylketone. Esters such as ethyl acetate; sulfoxides such as dimethyl sulfoxide; amides such as dimethylformamide, dimethylacetamide, and methylpyrrolidone. These solvents can be used alone or in combination of two or more.

The reaction temperature of the N-alkylation reaction is appropriately set according to the type of compound, solvent, and the like. This reaction temperature is usually −78 ° C. to 200 ° C., preferably 0 ° C. to 150 ° C., more preferably 20 ° C. to 130 ° C. The reaction time of the N-alkylation reaction is usually 10 seconds to 1 week, preferably 1 minute to 2 days, and more preferably 10 minutes to 20 hours.
The progress and completion of the N-alkylation reaction can be confirmed by analytical means such as normal phase or reverse phase thin film chromatography, high performance liquid chromatography (HPLC), NMR, infrared spectroscopy.

The disazo compound is a lyotropic liquid crystalline compound that can exhibit a liquid crystal phase when dissolved in a suitable solvent. Therefore, the disazo compound is oriented in a predetermined direction by casting the coating liquid containing the disazo compound on the substrate.
The lyotropic liquid crystalline compound is a compound having a property (lyotropic liquid crystalline) that causes a phase transition between an isotropic phase and a liquid crystal phase by changing the temperature and concentration of the solution in a solution state dissolved in a solvent. Means.

The polarizing film of the present invention contains at least one disazo compound represented by the above general formulas (I) to (VI). The polarizing film may contain two or more disazo compounds having different structures.
Since the disazo compound is oriented, the polarizing film of the present invention exhibits absorption dichroism at least at a part between wavelengths of 380 nm and 780 nm.
The polarization degree of the polarizing film is preferably 98% or more, more preferably 99% or more. The single transmittance of the polarizing film is preferably 35% or more, more preferably 40% or more.

The polarizing film has a small haze value, and thus is excellent in transparency. The haze value of the polarizing film of the present invention is, for example, 3.0% or less, preferably 2.5% or less.
In the present invention, the “haze value” refers to a value representing the ratio between the total light transmittance and the scattering transmittance of the polarizing film as a percentage. Haze value (%) = (scattered light transmittance / total light transmittance) × 100. The smaller the haze value, the better the transparency of the polarizing film.
The haze value can be measured according to JIS K 7136, for example.

The thickness of the polarizing film is not particularly limited. Since the polarizing film of the present invention can be formed by applying a coating liquid as will be described later, it can be formed thinner. Specifically, the thickness of the polarizing film is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1.0 μm.
In addition, the polarizing film of the present invention is excellent in heat resistance as in the case of a polarizing film formed from a conventional disazo compound.

(Coating solution of the present invention)
The coating liquid of the present invention contains at least one disazo compound represented by the above general formulas (I) to (VI) and a solvent for dissolving the disazo compound.

The solvent is not particularly limited, and a conventionally known solvent can be used, but an aqueous solvent is preferable. The aqueous solvent includes water, a hydrophilic solvent, and a mixed solvent of water and a hydrophilic solvent. The hydrophilic solvent is a solvent that can be dissolved substantially uniformly with water. Examples of the hydrophilic solvent include alcohols such as methanol, ethanol, methyl alcohol and isopropyl alcohol; glycols such as ethylene glycol and diethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; ketones such as acetone and methyl ethyl ketone; acetic acid And esters such as ethyl; The solvent is preferably water or a mixed solvent of water and a hydrophilic solvent.
Since the disazo compound of the present invention has a hydroxyalkyl group having an OH group, a SO ₃ M group, and OX, it is particularly excellent in solubility in an aqueous solvent.

The coating liquid exhibits a liquid crystal phase by changing the liquid temperature, the concentration of the disazo compound, and the like.
This liquid crystal phase is manifested by the formation of supramolecular aggregates in the liquid by the disazo compound. The liquid crystal phase is not particularly limited, and examples thereof include a nematic liquid crystal phase, a smectic liquid crystal phase, a cholesteric liquid crystal phase, and a hexagonal liquid crystal phase. The liquid crystal phase can be confirmed and identified by an optical pattern observed with a polarizing microscope.

The concentration of the disazo compound in the coating liquid is preferably adjusted so that the disazo compound exhibits a liquid crystal phase. The concentration of the disazo compound is 0.05% by mass to 50% by mass, preferably 0.5% by mass to 40% by mass, and more preferably 2% by mass to 30% by mass.
The method for preparing the coating liquid is not particularly limited. For example, the disazo compound may be added to a container containing a solvent, or the solvent may be added to a container containing a disazo compound.

The coating solution is adjusted to an appropriate pH. The pH of the coating solution is preferably about pH 4-10, more preferably about pH 6-8.
Furthermore, the temperature of the coating solution is preferably adjusted to about 10 ° C to 40 ° C, more preferably about 15 ° C to 30 ° C.

  Furthermore, an additive may be added to the coating liquid. Examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. . The concentration of the additive in the coating solution is preferably more than 0 and 10% by mass or less. Further, a surfactant may be added to the coating liquid. The surfactant is added to improve the wettability and coatability of the coating liquid to the substrate surface. It is preferable to use a nonionic surfactant as the surfactant. The concentration of the surfactant in the coating solution is preferably more than 0 and 5% by mass or less.

(Manufacturing method of polarizing film of the present invention)
The polarizing film of the present invention can be obtained, for example, by applying the coating liquid in a thin film on an appropriate substrate and drying it.

The polarizing film of the present invention can be preferably manufactured through the following steps A to C.
Process A: The process of apply | coating the said coating liquid on a base material, and forming a coating film.
Process B: The process of drying the said coating film.
Step C: selected from the group consisting of an aluminum salt, barium salt, lead salt, chromium salt, strontium salt, and a compound salt having two or more amino groups in the molecule on the surface of the coating film dried in Step B Contacting with a solution comprising at least one compound salt.
The base material may be subjected to orientation treatment on the side on which the coating liquid is applied.

<Process A>
Step A is a step of applying the above-described coating liquid onto a substrate to form a coating film.
The substrate is used to uniformly develop the coating liquid. If it is suitable for this purpose, the kind of base material will not be specifically limited, For example, a synthetic resin film (A film is the meaning containing what is generally called the sheet | seat), a glass plate, etc. can be used. . In a preferred embodiment, the substrate is a single polymer film, and in another preferred embodiment is a laminate comprising a polymer film. The laminate including the polymer film preferably further includes an alignment layer in the polymer film.

Although it does not specifically limit as said polymer film, The film (for example, haze value 3% or less) excellent in transparency is preferable.
Examples of the polymer film include polyesters such as polyethylene terephthalate and polyethylene naphthalate; celluloses such as diacetyl cellulose and triacetyl cellulose; polycarbonates; acrylics such as polymethyl methacrylate; polystyrenes, acrylonitrile / styrene copolymers, and the like. Polystyrene, Polypropylene, Polyolefin having a cyclic or norbornene structure, Olefin such as ethylene / propylene copolymer, Vinyl chloride, Amide such as nylon and aromatic polyamide, Imide such as polyimide, Polyethersulfone Polyether ether ketone system; Polyphenylene sulfide system; Vinyl alcohol system; Vinylidene chloride system; Vinyl butyral system; Acrylate system; Styrene based; and polymer film such as epoxy, polymer films or the like including mixtures of two or more thereof. Moreover, the said base material can also use the laminated body of two or more polymer films.
These polymer films are preferably stretched films.

  The thickness of the base material can be appropriately designed according to the strength and the like. From the viewpoint of reduction in thickness and weight, the thickness of the substrate is preferably 300 μm or less, more preferably 5 μm to 200 μm, and particularly preferably 10 μm to 100 μm.

When the said base material contains an orientation layer, the orientation layer can be formed by performing an orientation process to a base material. Examples of the alignment treatment include mechanical alignment treatment such as rubbing treatment, chemical alignment treatment such as photo-alignment treatment, and the like.
The mechanical orientation treatment can be performed by rubbing in one direction with a cloth or the like on one surface of the substrate (or one surface of an appropriate coating film formed on one surface of the substrate). The mechanical orientation treatment can be performed by stretching the substrate. By these mechanical alignment treatments, an alignment layer can be formed on one surface of the substrate.

  The chemical alignment treatment can be performed by forming a photo-alignment film containing an aligning agent on one surface of the substrate and irradiating the photo-alignment film with light. Thereby, an alignment layer can be formed on one surface of the substrate. Examples of the aligning agent include a polymer having a photoreactive functional group that causes a photochemical reaction such as a photoisomerization reaction, a photo-opening / closing ring reaction, a photodimerization reaction, a photolysis reaction, and a photofleece transition reaction. From the viewpoint of the alignment efficiency of the disazo compound, an imide-based polymer is preferable. The photo-alignment film can be formed by dissolving an aligning agent in an appropriate solvent to form a solution and applying it to a substrate.

  A coating solution is applied on the substrate (preferably on the alignment layer of the substrate). The coating liquid is preferably prepared with a viscosity of 0.1 mPa · s to 30 mPa · s, and more preferably a viscosity of 0.5 mPa · s to 3 mPa · s. However, the viscosity is a value measured by a rheometer (manufactured by Haake, product name: rheostress 600, measurement condition: double cone sensor shear rate 1000 (1 / s)).

  Since the above-mentioned coating liquid has a relatively low solid content concentration, it has excellent fluidity, and can be easily prepared within the optimum coating viscosity range of a coating machine (for example, a coater). Therefore, if the coating liquid is used, a thin and uniform coating film can be formed on the substrate.

  As a method for applying the coating liquid to one surface of the substrate, an application method using an appropriate coater may be employed. Examples of the coater include a bar coater, 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.

When a coating liquid in a liquid crystal phase is applied, shear stress is applied to the disazo compound during the flow of the coating liquid. Therefore, a coating film in which the disazo compound is oriented in a predetermined direction can be formed on the substrate.
Specifically, the disazo compound in the liquid crystal phase coating solution forms a supramolecular aggregate. When the coating liquid containing the disazo compound is cast in a predetermined direction, a shear stress is applied to the supramolecular aggregate. As a result, a coating film in which the long axis of the supramolecular aggregate made of a disazo compound is oriented in the casting direction can be formed on the substrate.
As described above, the disazo compound is oriented by the shear stress applied when the coating liquid is cast. However, the disazo compound can be oriented by other means.
Examples of the other means include (a) means for applying a coating liquid on a substrate subjected to orientation treatment, and (b) forming a coating film by applying the coating liquid on the substrate, and then applying a magnetic field. Alternatively, a means for applying an electric field may be used. Even if these other means are performed alone, a coating film in which the disazo compound is oriented in a predetermined direction can be formed.

<Process B>
Step B is a step of drying the coating film.
A coating solution is applied on the substrate to form a coating film, and then dried.
Drying can be performed by natural drying or forced drying. Examples of forced drying include reduced pressure drying, heat drying, and reduced pressure heat drying. Forced drying is performed by, for example, an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature control, a heated heat pipe roll, a heated It can be carried out using a drying means such as a metal belt.
The drying temperature is equal to or lower than the isotropic phase transition temperature of the coating liquid, and it is preferable to gradually raise the temperature from a low temperature to a high temperature. The drying temperature is preferably 50 ° C to 120 ° C, more preferably 20 ° C to 60 ° C. If it is this temperature range, it can prevent that the disazo compound contained in a coating liquid precipitates as a fine crystal. Therefore, a dry coating film having a small haze value can be obtained.
The drying time can be appropriately selected depending on the drying temperature and the type of solvent. In order to obtain a dry coating film with small thickness variation, the drying time is, for example, 1 minute to 30 minutes, and preferably 1 minute to 10 minutes.

The concentration of the coating film increases in the course of drying, and the oriented disazo compound is fixed. When the orientation of the disazo compound in the coating film is fixed, absorption dichroism, which is a characteristic of the polarizing film, is generated. The obtained dried coating film can be used as a polarizing film.
The thickness of the obtained dried coating film is preferably 0.05 μm to 5 μm. The amount of residual solvent in the dried coating film is preferably 1% by mass or less, more preferably 0.5% by mass or less.

The polarizing film produced by the above method has a small haze value (for example, 3.0% or less). The reason why a polarizing film having a small haze value can be obtained is estimated as follows.
The disazo compound of the present invention has solubility in a solvent, and particularly has high solubility in an aqueous solvent. In the coating liquid in which the disazo compound is dissolved in a solvent, the disazo compound is difficult to crystallize during the drying process. Therefore, if the disazo compound is used, a polarizing film having excellent transparency can be obtained.

<Process C>
Step C is a step of imparting water resistance to the surface of the dried coating film (the surface opposite to the bonding surface of the substrate).
Specifically, an aluminum salt, barium salt, lead salt, chromium salt, strontium salt, cerium salt, lanthanum salt, samarium salt, yttrium salt, copper salt, iron on the surface of the dried coating film formed in the above step B A solution containing at least one compound salt selected from the group consisting of a salt and a compound salt having two or more amino groups in the molecule is contacted.

  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. Examples include hydrochloride, melamine hydrochloride, and tetraaminopyrimidine hydrochloride. By forming such a compound salt layer, the surface of the dried coating film can be insolubilized or hardly soluble in water. Therefore, water resistance can be imparted to the dried coating film.

In the solution containing the above compound salt, the concentration of the compound salt is preferably 3% by mass to 40% by mass, and more preferably 5% by mass to 30% by mass.
Examples of the method for bringing the solution containing the above compound salt into contact with the surface of the dry coating include, for example, (a) a method of applying a solution containing the above compound salt to the surface of the dry coating, and (b) A method of immersing in a solution containing a compound salt can be employed. When these methods are adopted, it is preferable that the surface of the dried coating film is washed with water or an arbitrary solvent and then dried.

(Use of polarizing film of the present invention)
A polarizing film 1 formed by applying and drying the coating liquid on a substrate is laminated on a substrate 2 as shown in FIG.
The polarizing film 1 of the present invention is usually used in a state where it is laminated on a substrate 2. But the said polarizing film 1 can also be peeled from the said base material 2, and can also be used.
Another optical film may be further laminated on the polarizing film 1 of the present invention. Examples of other optical films include protective films and retardation films. A polarizing plate can be constituted by laminating a protective film and / or a retardation film on the polarizing film of the present invention.
In FIG. 2, the polarizing plate 5 by which the protective film 3 was laminated | stacked on the polarizing film 1 of this invention is shown. The polarizing plate 5 includes a base material 2, a polarizing film 1 laminated on the base material 2, and a protective film 3 laminated on the polarizing film 1. The substrate 2 has a function of protecting the polarizing film 1. For this reason, the polarizing plate 5 has the protective film 3 laminated on only one surface of the polarizing film 1.
Although not shown in the drawing, the polarizing plate 5 may be laminated with another optical film such as a retardation film.

  When another optical film is laminated on the polarizing film, practically any suitable adhesive layer is provided between them. Examples of the material for forming the adhesive layer include an adhesive, a pressure-sensitive adhesive, and an anchor coat agent.

The application of the polarizing film of the present invention is not particularly limited. The polarizing film of the present invention is used as a constituent member of an image display device such as a liquid crystal display device, for example.
When the image display device is a liquid crystal display device, preferred applications are OA devices such as televisions, personal computer monitors, notebook computers, copiers; mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable game machines, etc. Mobile devices; home appliances such as video cameras and microwave ovens; back monitors, car navigation system monitors, car audio equipment such as car audio; display equipment such as commercial store information monitors; monitoring monitors Security equipment; nursing care and medical equipment such as nursing monitors and medical monitors.

  Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following examples. In addition, each analysis method used by the Example and the comparative example is as follows.

(1) Confirmation of liquid crystal phase The liquid crystal phase of the coating liquid is obtained by sandwiching a small amount of the coating liquid between two glass slides and using a polarizing microscope (Olympus Co., Ltd., product name “OPTIPHOT-POL”) at room temperature. (23 ° C.).
(2) Thickness measurement The thickness of the polarizing film is determined by peeling a part of the polarizing film formed on the norbornene-based polymer film, a three-dimensional non-contact surface shape measurement system (product name “ Micromap MM5200 ") was used to measure the level difference between the film and the polarizing film.
(3) Measuring method of haze value The haze value was measured at room temperature (23 degreeC) using the haze measuring apparatus (Murakami Color Research Laboratory make, product name "HR-100"). This measurement was performed three times, and the average value was taken as the haze value.

[Example 1]
Water (10 mL) and glycidol (1.05 g, 14.2 mmol) are added to the disazo compound (2.00 g, 2.83 mmol) represented by the following structural formula (VII), heated to 100 ° C. and stirred for 3 hours. And N-alkylation reaction was carried out. A precipitate formed by adding this reaction solution to acetone is filtered, washed, and dried to obtain a disazo compound (1.61 g, 2.07 mmol, yield 73%) represented by the following structural formula (VIII). Obtained.
In addition, the structure of the obtained disazo compound was confirmed using NMR (nuclear magnetic resonance apparatus).
¹ H NMR (d6-DMSO) 9.03 (d, ArH, 1H), 8.59 (s, ArH, 1H), 8.38 (d, ArH, 1H), 8.1-7.9 (m , ArH, 4H), 7.81 (s, ArH, 1H), 7.46 (s, ArH, 1H), 7.20 (d, ArH, 2H), 6.89 (brs, ArNH, 1H), 5.07 (d, CH—OH, 1H), 4.88 (t, CH ₂ —OH, 1H), 3.91 (s, OCH ₃ , 3H), 3.8-3.7 (m, − _{NHCH 2 CH (OH) CH 2} OH, 1H), 3.5-3.1 (m, -NHCH 2 CH (OH) CH 2 OH, 4H).

Subsequently, the disazo compound represented by the above structural formula (VIII) was dissolved in ion-exchanged water to prepare a coating solution for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

A bar coater (manufactured by BUSHMAN, product name “Mayer rot HS4”) is formed on the treated surface of a norbornene-based polymer film (trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.) subjected to rubbing treatment and corona treatment. ) And air-dried at room temperature. The coating film after drying is a polarizing film.
The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 2.4%.

[Example 2]
Water (10 mL) and glycerol diglycidyl ether (1.73 g, 8.49 mmol) are added to the disazo compound (2.00 g, 2.83 mmol) represented by the structural formula (VII), and heated to 120 ° C. The mixture was stirred for 10 hours to allow N-alkylation reaction. The precipitate formed by adding this reaction solution to acetone is filtered, washed, and dried to obtain a disazo compound (2.20 g, 2.37 mmol, yield 84%) represented by the following structural formula (IX). Obtained.
In addition, the structure of the obtained disazo compound was confirmed using NMR.
¹ H NMR (d6-DMSO) 9.02 (d, ArH, 1H), 8.58 (s, ArH, 1H), 8.38 (d, ArH, 1H), 8.1-7.9 (m , ArH, 4H), 7.89 (s, ArH, 1H), 7.45 (s, ArH, 2H), 7.24 (d, ArH, 2H), 6.87 (brs, ArNH, 1H), 5.1-4.4 (m, OH, 4H), 3.91 (s, OCH ₃ , 3H), 4.0-3.3 (m, —NHCH ₂ CH (OH) CH ₂ OH, 1H) _{, 3.1-3.0 (m, -NHCH 2,} 2H).

Subsequently, the disazo compound represented by the above structural formula (IX) was dissolved in ion-exchanged water to prepare a coating solution for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

  In the same manner as in Example 1, the coating solution was applied onto the treated surface of the norbornene-based polymer film and dried. The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 1.3%.

[Example 3]
Water (10 mL), hydroquinone (catalytic amount) and glycidyl methacrylate (0.81 g, 5.67 mmol) were added to the disazo compound (2.00 g, 2.83 mmol) represented by the structural formula (VII), and 80 The mixture was heated to ° C. and stirred for 15 hours to carry out N-alkylation reaction. A precipitate formed by adding this reaction solution to acetone is filtered, washed, and dried to obtain a disazo compound (1.93 g, 2.28 mmol, yield 80%) represented by the following structural formula (X). Obtained.
In addition, the structure of the obtained disazo compound was confirmed using NMR.
¹ H NMR (d6-DMSO) 9.02 (d, ArH, 1H), 8.58 (s, ArH, 1H), 8.39 (d, ArH, 1H), 8.1-7.9 (m , ArH, 4H), 7.82 (s, ArH, 1H), 7.48 (d, ArH, 2H), 7.19 (d, ArH, 2H), 6.91 (brs, ArNH, 1H), 6.15 (s, cis-HHC = C-, 1H), 5.75 (s, trans-HHC = C-, 1H), 5.44 (d, CH-OH, 1H), 4.2-4 _{.0 (m, -NHCH 2 CH (} OH) CH 2 OMc, 3H), 3.91 (s, -OCH 3, 3H), 3.5-3.1 (m, -NHCH 2 CH (OH) CH _{2 OH, 4H), 3.6-3.4 (} m, -NHCH 2 CH (OH) CH 2 OMc, 3H), 1.93 (s, CH , 3H).

Next, the disazo compound represented by the structural formula (X) was dissolved in ion-exchanged water to prepare a coating liquid for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

  In the same manner as in Example 1, the coating solution was applied onto the treated surface of the norbornene-based polymer film and dried. The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 2.9%.

[Example 4]
Water (5 mL) and glycidol (0.58 g, 7.88 mmol) are added to an azobenzene dye compound (1.00 mmol) represented by the following structural formula (XI), heated to 120 ° C. and stirred for 3 hours. -Alkylation reaction. A precipitate formed by adding this reaction solution to acetone is filtered, washed, and dried to obtain a disazo compound (0.95 g, 1.35 mmol, yield 85%) represented by the following structural formula (XII). Obtained.
In addition, the structure of the obtained disazo compound was confirmed using NMR.
¹ H NMR (d6-DMSO) 12.93 (s, ArOH, 1H), 9.22 (s, ArH, 1H), 8.98 (d, ArH, 1H), 8.5-8.0 (m , ArH, 8H), 7.69 (d, ArH, 1H), 7.33 (d, ArH, 1H), 6.99 (d, ArH, 1H), 5.07 (d, CH-OH, 1H) ), 4.88 (t, CH ₂ —OH, 1H), 3.84 (m, —NHCH ₂ CH (OH) CH ₂ OH, 1H), 3.5-3.1 (m, —NHCH ₂ CH _{(OH) CH 2 OH, 4H} ).

Subsequently, the disazo compound represented by the structural formula (XII) was dissolved in ion-exchanged water to prepare a coating solution for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

  In the same manner as in Example 1, the coating solution was applied onto the treated surface of the norbornene-based polymer film and dried. The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 2.2%.

[Comparative Example 1]
The disazo compound represented by the structural formula (VII) was dissolved in ion-exchanged water to prepare a coating solution for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

  In the same manner as in Example 1, the coating solution was applied onto the treated surface of the norbornene-based polymer film and dried. The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 7.4%.

[Comparative Example 2]
The disazo compound represented by the structural formula (XI) was dissolved in ion-exchanged water to prepare a coating solution for forming a 5% by mass polarizing film.
When this coating solution was observed with a polarizing microscope, the coating solution showed a nematic liquid crystal phase.

  In the same manner as in Example 1, the coating solution was applied onto the treated surface of the norbornene-based polymer film and dried. The thickness of the obtained polarizing film was 0.4 μm. Moreover, the haze value of this polarizing film was 5.3%.

The polarizing film of this invention can be utilized for the structural member of a liquid crystal display device, polarized sunglasses, etc., for example.
The coating liquid of this invention can be utilized when manufacturing the said polarizing film, for example.
The disazo compound of the present invention can be used, for example, as a material for forming the polarizing film, a material for forming other optical films, and a dye.

The fragmentary sectional view showing the polarizing film concerning one embodiment. The fragmentary sectional view showing the polarizing plate concerning one embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Polarizing film, 2 ... Base material, 3 ... Protective film, 5 ... Polarizing plate

Claims (8)

A polarizing film comprising a disazo compound represented by the following general formula (I).

In the general formula (I), Q ₁ represents an aryl group which may have a substituent, Q ₂ represents an arylene group which may have a substituent, and M represents a counter ion. , X is a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms (non-adjacent carbon atom in the alkyl group may be replaced by an oxygen atom), methacryl group, or acryl group M represents an integer of 1 or 2, and n represents an integer of 1 to 4. The polarizing film according to claim 1, wherein the disazo compound is at least one of compounds represented by the following general formula (II) or general formula (III).

In General Formula (II) and General Formula (III), Q ₁ , Q ₂ , M and X are the same as those in General Formula (I). Q _{1 in the} general formula (II) and the general formula (III) is a phenyl group which may have a substituent, and Q ₂ is a naphthylene group which may have a substituent. 2. The polarizing film according to 2. The polarizing film according to claim 1, wherein the disazo compound is at least one of compounds represented by the following general formula (V) or general formula (VI).

In General Formula (V) and General Formula (VI), A and B are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. hydroxyalkyl group, an alkylamino group having 1 to 6 carbon atoms, phenylamino group having 6 to 20 carbon atoms, acylamino group having 1 to 6 carbon atoms, a halogeno group, a nitro group, a cyano group, an amino group, -SO ₃ M group , -COOM group, or -OM group, and X, M, m, and n are the same as those in formula (I).   The polarizing film according to claim 1, which has a haze value of 3.0% or less. A coating liquid for forming a polarizing film,
The coating liquid containing the disazo compound represented by the following general formula (I), and a solvent.

In the general formula (I), Q ₁ represents an aryl group which may have a substituent, Q ₂ represents an arylene group which may have a substituent, and M represents a counter ion. , X is a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms (non-adjacent carbon atom in the alkyl group may be replaced by an oxygen atom), methacryl group, or acryl group M represents an integer of 1 or 2, and n represents an integer of 1 to 4. The coating liquid according to claim 6, wherein the disazo compound is at least one of compounds represented by the following general formula (III) or general formula (VI).

 In general formula (III), Q ₁ , Q ₂ , M and X are the same as in general formula (I), and in general formula (VI), A and B are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or 1 to 6 carbon atoms. Alkoxy group having 1 to 6 carbon atoms, alkylamino group having 1 to 6 carbon atoms, phenylamino group having 6 to 20 carbon atoms, acylamino group having 1 to 6 carbon atoms, halogeno group, nitro group, cyano Group, amino group, -SO ₃ Represents an M group, a -COOM group, or a -OM group, and X, M, m, and n are the same as those in formula (I).   The manufacturing method of the polarizing film which forms a polarizing film by apply | coating the coating liquid of Claim 6 or 7 on a base material, and drying.

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