JP2010204527A - Polarizer, image display device, and method of manufacturing polarizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizer superior in scratch resistance. <P>SOLUTION: This polarizer contains azobenzene compound expressed by general formula (I), and polyacrylamide. In general formula (I), R<SB>1</SB>shows a substituted or non-substituted aryl group, R<SB>2</SB>shows a substituted or non-substituted arylene group, R<SB>3</SB>independently shows a hydrogen atom, substituted or non-substituted alkyl group, substituted or non-substituted acetyl group, substituted or non-substituted benzoyl group, or substituted or non-substituted phenyl group, M shows a counter ion, m shows an integer of 1 or 2, and n shows an integer of 1-3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizer excellent in scratch resistance and a method for producing the polarizer.

The polarizer is an optical member having a function of transmitting specific linearly polarized light from polarized light or natural light. The polarizer is used, for example, as a constituent member of a liquid crystal display device or a lens of polarized sunglasses.
A general-purpose polarizer can be obtained, for example, by stretching a polyvinyl alcohol film dyed with iodine.
A polarizer obtained by a method (solution casting method) of applying a solution containing a lyotropic liquid crystalline compound onto a substrate is also known.
For example, Patent Document 1 discloses a polarizer obtained by applying a solution containing an azobenzene compound having a specific structure on a substrate.

JP 2007-126628 A

The polarizer of Patent Document 1 has excellent heat resistance and absorption dichroism. Furthermore, since the polarizer can be formed by a solution casting method, it is much thinner than a polarizer made of a polyvinyl alcohol film dyed with iodine.
However, since the polarizer of Patent Document 1 is inferior in scratch resistance, improvement is required.

A first object of the present invention is to provide a polarizer containing an azobenzene compound and excellent in scratch resistance, and an image display device having the polarizer.
The second object of the present invention is to provide a method for producing a polarizer excellent in scratch resistance.

The present inventors have conducted the following studies and completed the present invention.
The azobenzene compound dissolved in the aqueous solvent is laminated by π-π interaction, and these form a supramolecular aggregate, thereby producing a liquid crystal phase. A polarizer is obtained by applying a solution obtained by dissolving the azobenzene compound in a solvent onto a substrate and applying an external field such as a magnetic field as necessary to orient the supramolecular aggregate of the azobenzene compound. It is done.
However, since the supramolecular aggregate in the solution is formed in a matrix such as an aqueous solvent, the supramolecular aggregate is unstable with respect to stress. In addition, since a slight amount of aqueous solvent remains in the polarizer, the supramolecular aggregate contained in the polarizer is also unstable with respect to stress. Therefore, it is estimated that the conventional polarizer is easily damaged when a frictional force or the like is applied to the surface thereof. Therefore, it is considered that the presence of a rigid component that is compatible with water as the matrix can enhance the stability of the supramolecular aggregate against the stress of the matrix. Under such knowledge, the present inventor examined various compounds that do not inhibit the orientation of the azobenzene compound and are compatible with water, and completed the present invention.

  The polarizer of the present invention contains an azobenzene compound represented by the following general formula (I) and polyacrylamide.

R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a substituted or unsubstituted arylene group, and R ₃ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, substituted or unsubstituted A substituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, or a group represented by the following general formula (II) is represented, M represents a counter ion, m represents 1 or 2 N represents an integer of 1 to 3.

  X represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms (including an alkyl group in which non-adjacent carbon atoms are substituted with oxygen atoms), a methacryl group, or an acrylic group.

The polarizer of the present invention can be obtained, for example, by a solution casting method in which a coating solution containing an azobenzene compound, polyacrylamide, and an aqueous solvent is coated on a substrate.
The polarizer of the present invention has good polarization characteristics because the azobenzene compound forms a supramolecular aggregate and is oriented in a predetermined direction.
Furthermore, the polarizer of the present invention contains polyacrylamide. Polyacrylamide is a relatively rigid polymer with high polarity. This polyacrylamide exists as a matrix and retains the orientation of the supramolecular aggregate of the azobenzene compound due to its high polarity and rigidity.
For this reason, the stability of the supramolecular aggregate is enhanced, and even when a frictional force or the like is applied to the polarizer of the present invention, the surface of the polarizer is hardly damaged.

In a preferred polarizer of the present invention, the polyacrylamide is contained in an amount of 25 to 900 parts by mass with respect to 100 parts by mass of the azobenzene compound.
In another preferred polarizer of the present invention, the polyacrylamide includes nonionic polyacrylamide.
In another preferred polarizer of the present invention, the azobenzene compound has water solubility.

According to another aspect of the present invention, an image display device is provided.
The image display apparatus of the present invention has any one of the polarizers as its constituent members.

According to another situation of this invention, the manufacturing method of a polarizer is provided.
The manufacturing method of the polarizer of this invention has the process of coating on the base material the coating liquid containing the azobenzene compound represented by the said general formula (I), polyacrylamide, and an aqueous solvent.

The polarizer of the present invention is excellent in scratch resistance and has predetermined polarization characteristics.
According to the method for producing a polarizer of the present invention, a polarizer having excellent scratch resistance can be easily produced by a solution casting method.

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

(Azobenzene compound)
The polarizer of the present invention contains an azobenzene compound represented by the following general formula (I) and polyacrylamide.
In the present specification, “Y to Z” means “Y or more and Z or less”.

In general formula (I), R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a substituted or unsubstituted arylene group, and R ₃ independently represents a hydrogen atom, substituted or unsubstituted. An alkyl group, a substituted or unsubstituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, or a group represented by the following general formula (II), and M represents a counter ion , M represents an integer of 1 or 2, and n represents an integer of 1 to 3. When m is 2, each R ₃ is independently the same or different.

In the general formula (II), X represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms (including an alkyl group in which an adjacent carbon atom in the alkyl group is substituted with an oxygen atom), methacryl Represents a group or an acrylic group. As a C1-C18 alkyl group by which the carbon atom which is not adjacent in the said alkyl group is substituted by the oxygen atom, a C1-C18 alkyl ether group etc. are mentioned, for example.
In the present specification, “substituted or unsubstituted” means “substituted with a substituent or not substituted with a substituent”.

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 (l).

R _{3 in the} general formula (I) is preferably any one of a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted acetyl group, or a group represented by the general formula (II). More preferably a hydrogen atom or a group represented by the above general formula (II).
Examples of the substituted or unsubstituted alkyl group for R ₃ include substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.
When the alkyl group, acetyl group, benzoyl group, or phenyl group of R ₃ has a substituent, examples of the substituent include each substituent exemplified in the following aryl group or arylene group.

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 the 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.

  M in the general formula (I) is preferably 1. Further, n in the general formula (I) is preferably 1 or 2.

When X of the said general formula (II) is a C1-C18 alkyl group, the carbon number becomes like this. Preferably it is 1-12, More preferably, it is 2-8. The alkyl group having 1 to 18 carbon atoms may be linear or branched. Preferably, the alkyl group is linear. Examples of the alkyl group having 1 to 18 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, pentyl group, isopentyl group, and hexyl group.
When X in the general formula (II) is a C1-C18 alkyl group having a substituent, examples of the substituent include a phenyl group, a halogeno group such as fluorine, a hydroxyl group, a glycidyl group, and a sulfonic acid. Group, carboxyl group, amino group, nitro group and the like. Preferably, the substituent is one selected from a phenyl group, a halogeno group such as fluorine, a hydroxyl group, and a glycidyl group. The alkyl group of X may be substituted with one or more substituents selected from these.

In the general formula (I), examples of the aryl group represented by R ₁ include a phenyl group and a condensed ring group in which two or more benzene rings are condensed, such as a naphthyl group.
Examples of the arylene group represented by R ₂ include a condensed ring group in which two or more benzene rings are condensed, such as a naphthylene group, in addition to a phenylene group.

Aryl group or arylene group of R ₁ or R ₂ may be substituted or may not have a substituent. Whether the aryl group or arylene group is substituted or unsubstituted, the solvent solubility of the azobenzene compound having a —SO ₃ M group or the like is hardly changed. The azobenzene compound has water solubility and can form a good lyotropic liquid crystal phase.

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, an alkylamino group having 1 to 6 carbon atoms, and phenyl. amino group, an acylamino group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms such as dihydroxypropyl group, a carboxyl group, a sulfonic acid group such as -SO 3 _M group, a hydroxyl group, a cyano group, a nitro group, an amino Group, halogeno group and the like. Preferably, the substituent is one selected from an alkoxy group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a carboxyl group, a sulfonic acid group, and a nitro group. An azobenzene compound having such a substituent is particularly excellent in water solubility. These substituents may be substituted alone or in combination of two or more. Moreover, the said substituent may be substituted by arbitrary ratios.

Wherein R ₁ in the general formula (I) is preferably a substituted or unsubstituted phenyl group, more preferably a phenyl group having the substituent.
R ₂ is preferably a substituted or unsubstituted naphthylene group, more preferably a naphthylene group having the substituent, and particularly preferably a 1,4-naphthylene group having the substituent.

The azobenzene compound in which R _{1 in the} general formula (I) is a substituted or unsubstituted phenyl group and R ₂ is a substituted or unsubstituted 1,4-naphthylene group is represented by the following general formula (III).

In the general formula (III), R ₃ , M, m and n are the same as those in the general formula (I).

In the general formula (III), A and B represent substituents, and a and b represent the number of substitutions. A and B are each independently an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylamino group having 1 to 6 carbon atoms, a phenylamino group, or an acylamino having 1 to 6 carbon atoms. Group, a hydroxyalkyl group having 1 to 6 carbon atoms such as a dihydroxypropyl group, a carboxyl group, a sulfonic acid group such as a —SO ₃ M group, a hydroxyl group, a cyano group, a nitro group, an amino group, a halogeno group, etc., preferably , An alkoxy group having 1 to 6 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a carboxyl group, a sulfonic acid group, and a nitro group. Said a and b are integers of 0-5, Preferably they are 1 or 2. When the a is 2 or more, the substituents A may be the same or different. When b is 2 or more, the substituents B may be the same or different.

  The azo compound represented by the general formula (I) can be synthesized, for example, according to Yutaka Hosoda, “Theoretical Production, Dye Chemistry (5th Edition)” (published July 15, 1968, Gihodo, pages 135-152).

(Polyacrylamide)
The polyacrylamide contained in the polarizer of the present invention is a water-soluble polymer.
Polyacrylamide is a linear polymer mainly composed of a polymer or copolymer of acrylamide monomers.
Examples of the acrylamide monomers include N-substituted lower alkyl acrylamide monomers such as an acrylamide monomer, a methacrylamide monomer, and an N-ethyl acrylamide monomer, and an acrylamide monomer and / or a methacrylamide monomer are preferable.

The polyacrylamide used in the present invention is not particularly limited as long as it is compatible with the azobenzene compound and has water solubility.
For example, in the present invention, nonionic, cationic, anionic, or amphoteric polyacrylamide can be used.
Examples of nonionic polyacrylamides include polymers or copolymers of acrylamide monomers, or copolymers of acrylamide monomers and nonionic monomers.
Examples of the cationic polyacrylamide include copolymers of acrylamide monomers and cationic monomers. Examples of cationic monomers include tertiary amine monomers such as allylamine or salts thereof, and quaternary ammonium salt monomers. Examples of anionic polyacrylamide include copolymers of acrylamide monomers and anionic monomers. Is mentioned. Examples of the anionic monomer include a monomer having a carboxyl group and a monomer having a sulfonic acid group.
In the present invention, it is preferable to use nonionic polyacrylamide. The azobenzene compound has an anionic group such as a sulfonic acid group. For this reason, when cationic polyacrylamide is used, the azobenzene compound and the cationic polyacrylamide are ion-bonded to each other, which may cause aggregation. When an anionic polyacrylamide is used, the azobenzene compound and the anionic polyacrylamide are compatible with each other, so that the azobenzene compound may not be in a liquid crystal state. Such a problem does not occur when nonionic polyacrylamide is used.

The weight average molecular weight of the polyacrylamide is preferably relatively small so that the viscosity of the coating solution does not become extremely viscous. Specifically, the weight average molecular weight of the polyacrylamide is preferably 500 to 100,000.
However, the weight average molecular weight can be measured according to a gel permeation chromatography method (polystyrene standard) using a tetrahydrofuran solvent.
The content of the polyacrylamide is not particularly limited and can be set as appropriate. For example, the content of the polyacrylamide is preferably 25 parts by weight to 900 parts by weight, more preferably 50 parts by weight to 400 parts by weight, and particularly preferably 80 parts by weight with respect to 100 parts by weight of the azobenzene compound. Part to 200 parts by mass. If the polyacrylamide content is less than 25 parts by mass, the scratch resistance of the polarizer may not be sufficiently improved. On the other hand, when the content of polyacrylamide exceeds 900 parts by mass, the polarization degree of the polarizer may be lowered. In addition, if content of polyacrylamide is 80 mass parts-200 mass parts, the polarizer which has a high polarization degree may be obtained.

  The polarizer of the present invention may contain other polymers and additives as long as the effects of the present invention are not impaired.

Since the supramolecular aggregate of the azobenzene compound is oriented in a predetermined direction, the polarizer of the present invention exhibits absorption dichroism at least at a part between wavelengths of 380 nm and 780 nm.
Furthermore, since the polarizer contains polyacrylamide, it has excellent scratch resistance.
The polyacrylamide has high polarity and is rigid. Due to its high polarity and rigidity, polyacrylamide has an action of maintaining the orientation of the azobenzene compound without inhibiting the orientation.
For this reason, even if a frictional force or the like is applied to the polarizer, the orientation of the supramolecular aggregate of the azobenzene compound is hardly disturbed, and as a result, the surface of the polarizer is hardly damaged.
Even when a relatively large amount of aqueous solvent remains in the polarizer, the stability of the azobenzene compound is maintained by the presence of the polyacrylamide, so that the surface of the polarizer is hardly damaged.
In addition, the polarizer of the present invention has good heat resistance as well as a polarizer formed of a conventional azobenzene compound.

The degree of polarization of the polarizer is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more. A polarizer having a degree of polarization of 92% or more can be obtained by appropriately setting the content of polyacrylamide.
However, the degree of polarization can be measured by the method described in the following examples.
The transmittance (T [550]) of the polarizer is preferably 35% or more, more preferably 40% or more. However, the transmittance can be measured using, for example, a spectrophotometer (manufactured by JASCO Corporation, product name “V-7100”).

  The thickness of the polarizer is not particularly limited. Since the polarizer of the present invention can be formed by a solution casting method as will be described later, it can be formed thinner. Specifically, the thickness of the polarizer is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1.0 μm.

(Manufacturing method of the polarizer of the present invention)
The polarizer of the present invention can be obtained, for example, by coating a coating liquid containing the azobenzene compound and the polyacrylamide on a suitable substrate in a thin film and drying it.

The polarizer of the present invention can be preferably manufactured through the following step A and step B, and the step C below may be performed after the step B as necessary.
Step A: A step of coating a coating liquid containing the azobenzene compound and the polyacrylamide on a substrate to form a coating film.
Process B: The process of drying the said coating film.
Step C: A step of applying a water resistance treatment to the surface of the coating film dried in Step B.
The base material may be provided with an orientation regulating force on the surface side on which the coating liquid is applied.

<Process A>
Step A is a step in which the coating liquid is applied onto a substrate to form a coating film.
The coating liquid of this invention contains the azobenzene compound represented by the said general formula (I), the said polyacrylamide, and the solvent which dissolves the said azobenzene compound and polyacrylamide.

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; As the aqueous solvent, water or a mixed solvent of water and a hydrophilic solvent is preferably used.
Since the azobenzene compound has a —NHR ₃ group and a —SO ₃ M group, it is soluble in water and particularly excellent in solubility in the aqueous solvent.

The coating liquid exhibits a liquid crystal phase by changing the liquid temperature, the concentration of the azobenzene compound, and the like.
This liquid crystal phase is manifested by the formation of supramolecular aggregates in the liquid by the azobenzene compound. The liquid crystal phase is not particularly limited, and examples thereof include a nematic liquid crystal phase, a middle 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 azobenzene compound in the coating solution is preferably adjusted so that the azobenzene compound exhibits a liquid crystal phase. The concentration of the azobenzene compound in the coating solution is 0.1% by mass to 30% by mass, preferably 1% by mass to 30% by mass, and more preferably 2% by mass to 20% by mass.
Moreover, the density | concentration of the polyacrylamide in a coating liquid is 0.5 mass%-50 mass%, Preferably it is 1 mass%-40 mass%, More preferably, it is 3 mass%-30 mass%.
The method for preparing the coating liquid is not particularly limited. For example, the azobenzene compound and polyacrylamide may be added to a container containing a solvent, or the solvent may be added to a container containing azobenzene compound and polyacrylamide. Good.

The coating solution is adjusted to an appropriate pH. The pH of the coating solution is preferably about pH 2 to 10, more preferably about pH 6 to 8.
Furthermore, the temperature of the coating liquid is preferably adjusted to 10 ° C to 40 ° C, more preferably 15 ° C to 30 ° C.

  Furthermore, an additive may be added to the coating liquid. Examples of the additive include a compatibilizing agent, a surfactant, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, an antistatic agent, and a thickener. The concentration of the additive in the coating solution is preferably more than 0 and 10% by mass or less.

  A base material is used in order to expand | deploy a coating liquid uniformly. If it is suitable for this purpose, the kind of base material will not be specifically limited, For example, a polymer film (A film includes what is generally called a sheet | seat), a glass plate, etc. can be used. In a preferred embodiment, a polymer film is used as the substrate. In another preferred embodiment, an alignment substrate is used as the substrate. The alignment substrate is a substrate having an alignment regulating force on at least the surface. If the said orientation base material is used, an azobenzene compound can be easily orientated by apply | coating a coating liquid to this.

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 material 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; polystyrene, acrylonitrile / styrene copolymer Examples thereof include styrenes such as coalescence; olefins such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene / propylene copolymers. In order to satisfactorily orient the azobenzene compound, it is preferable to use an olefin film, and it is more preferable to use a norbornene film. As said norbornene-type film, the brand name "ZEONOR" by Nippon Zeon Co., Ltd. is mentioned, for example.

The alignment substrate is obtained by applying an alignment regulating force to the surface of a substrate (for example, a polymer film) or a surface layer formed on the substrate.
The method for applying the alignment regulating force is not particularly limited. Examples of the method include a method of performing a rubbing treatment on the surface of the substrate, a method of forming a surface layer such as polyimide on the substrate, and a rubbing treatment on the surface layer, and a photoreaction (light) on the substrate. Examples include a method of forming a surface layer containing a compound that causes isomerization, photodimerization, photolysis, etc.) and imparting directionality to the surface layer by irradiating the surface layer with light.

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.
As a method for applying the coating liquid on one surface of the substrate, a coating 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 state is applied onto a substrate, shear stress is applied to the supramolecular aggregate of the azobenzene compound during the flow of the coating liquid. Therefore, a coating film in which supramolecular aggregates of azobenzene compounds are oriented in a predetermined direction can be formed on the substrate. Moreover, when a base material is an orientation base material, an azobenzene compound orientates according to the directionality.
In addition, in order to improve the orientation of the azobenzene compound, a magnetic field or an electric field may be applied as necessary after forming the coating film.

<Process B>
Step B is a step of drying the coating film.
After coating a coating liquid on a base material to form a coating film, this is 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. Natural drying is preferable.
The drying time can be appropriately selected depending on the drying temperature and the type of solvent. For example, in the case of natural drying, the drying time is preferably 1 second to 120 minutes, more preferably 10 seconds to 5 minutes.

The concentration of the coating film increases in the course of drying, and the oriented azobenzene compound is fixed. By fixing the orientation of the azobenzene compound in the coating film, absorption dichroism, which is a characteristic of a polarizer, is produced. The obtained dried coating film can be used as a polarizer.
The thickness of the obtained dried coating film is preferably 0.05 μm to 5 μm.

<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 base material).
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.

By performing Step C, a layer containing the compound salt is formed on the surface of the dried coating film. By forming such a 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 (polarizer).
In addition, you may wash | clean the surface of the obtained polarizer with water or a washing | cleaning liquid as needed.

(Use of the polarizer of the present invention)
A polarizer 1 obtained by applying the coating liquid onto a substrate is laminated on a substrate 2 as shown in FIG.
The polarizer 1 of this invention is normally used in the state laminated | stacked on the base material 2. FIG. But the said polarizer 1 can also peel from the said base material 2, and can also be used.
The polarizer 1 of the present invention may be further laminated with another optical film. 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 polarizer of the present invention.
In FIG. 2, the polarizing plate 5 by which the protective film 3 was laminated | stacked on the polarizer 1 of this invention is shown. The polarizing plate 5 includes a base material 2, a polarizer 1 laminated on the base material 2, and a protective film 3 laminated on the polarizer 1. The substrate 2 has a function of protecting the polarizer 1. For this reason, as for the said polarizing plate 5, the protective film 3 is laminated | stacked only on one side of the polarizer 1. FIG.
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 polarizer, 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 use of the polarizer of the present invention is not particularly limited. The polarizer of the present invention is used as a constituent member of an image display device such as a liquid crystal display device or an organic EL display device.
In the case where the image display device is a liquid crystal display device, preferred applications are a television, a portable device, a video camera, and the like.

  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.

[Measurement method of polarizer thickness]
For the thickness of the polarizer, a part of the polarizer formed on the norbornene-based polymer film was peeled off, and a three-dimensional non-contact surface shape measurement system (manufactured by Ryoka System Co., Ltd., product name “Micromap MM5200”) was used. The step between the film and the polarizer was measured.
[Observation of polarizer surface]
The surface of the polarizer was observed in a crossed Nicol state at a magnification of 20 times using a polarizing microscope (manufactured by Olympus Corporation, product name “OPTIPHOT-POL”).
[Measurement method of polarization degree]
Using a spectrophotometer equipped with a Glan-Thompson polarizer (manufactured by JASCO Corporation, product name “V-7100”), linearly polarized light having a wavelength of 380 nm to 780 nm was incident on the polarizer, and a polarized light transmission spectrum was measured. Visibility was corrected from this spectrum to obtain Y1 and Y2. The degree of polarization was determined by substituting Y1 and Y2 into the following equation.
Formula: Polarization degree = (Y1-Y2) / (Y1 + Y2)
Y1 represents the transmittance of linearly polarized light in the maximum transmittance direction, and Y2 represents the transmittance of linearly polarized light in the direction orthogonal to the maximum transmittance direction.

[Example 1]
p-Anisidine and 8-amino-2-naphthalenesulfonic acid were subjected to diazotization and coupling reaction according to the method described in the following literature to obtain a monoazo compound. This monoazo compound was diazotized according to the method described in the same document, and then further reacted with 3-amino-5-naphthol-2,7-disulfonic acid sodium salt. The obtained crude product was salted out with lithium chloride to obtain an azobenzene compound represented by the following structural formula (IV).
Reference: Yutaka Hosoda, “Theoretical Manufacturing, Dye Chemistry (5th Edition)” (pages 135-152, published July 15, 1968 by Gihodo).

100 parts by weight of the azobenzene compound of the structural formula (IV), 200 parts by weight of a 50% polyacrylamide aqueous solution (manufactured by Aldrich, polyacrylamide weight average molecular weight: 1500), and 1900 parts by weight of ion-exchanged water, A coating solution was prepared. In addition, since 200 mass parts of 50% aqueous solution of polyacrylamide was mixed, the quantity of the polyacrylamide solid content in a coating liquid is 100 mass parts. This coating solution is applied to a bar coater (manufactured by BUSHMAN, product name “Mayer rot HS4” on the treated surface of a norbornene polymer film (manufactured by ZEON Corporation, trade name “ZEONOR”) subjected to rubbing treatment and corona treatment )) And air-dried at room temperature for 60 seconds. The coating film after drying is a polarizer.
The thickness of the obtained polarizer was 0.4 μm. The polarization degree of the polarizer was 94%.

When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, the surface of this polarizer was rubbed back and forth about 5 times using a medicine-wrapping paper (manufactured by Hakuaisha, trade name “pure white imitation”). Then, when the surface (rubbed surface) of the polarizer was observed with a polarizing microscope, no defects were generated.

[Example 2]
A polarizer was produced in the same manner as in Example 1 except that the amount of the 50% aqueous solution of polyacrylamide was changed to 800 parts by mass. In addition, since 800 mass parts of 50% aqueous solution of polyacrylamide was mixed, the amount of polyacrylamide is 400 mass parts.

The thickness of the polarizer of Example 2 was 0.4 μm. The polarization degree of the polarizer was 85%.
When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, after the surface of this polarizer was rubbed with medicine-wrapping paper in the same manner as in Example 1, the surface was observed with a polarizing microscope, and no defects were generated.

[Comparative Example 1]
A polarizer was produced in the same manner as in Example 1 except that a 50% aqueous solution of polyacrylamide was not added.
The thickness of the polarizer of Comparative Example 1 was 0.4 μm. The polarization degree of the polarizer was 96%.
When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, the surface of this polarizer was rubbed with a medicine-wrapping paper in the same manner as in Example 1, and then the surface was observed with a polarizing microscope. As a result, the anisotropy of the polarizer disappeared, and Defects (innumerable scratches) occurred.

[Example 3]
4-Nitroaniline and 8-amino-2-naphthalenesulfonic acid were diazotized and coupled in accordance with the method described in the above literature to obtain a monoazo compound. This monoazo compound was diazotized according to the method described in the same document, and then further reacted with 1-amino-8-naphthol-2,4-disulfonic acid sodium salt. The obtained crude product was salted out with lithium chloride to obtain an azobenzene compound represented by the following structural formula (V).

A polarizer was produced in the same manner as in Example 1 except that the azobenzene compound of the structural formula (V) was used instead of the azobenzene compound of the structural formula (IV).
The thickness of the polarizer of Example 3 was 0.4 μm. The polarization degree of the polarizer was 98%.
When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, after the surface of this polarizer was rubbed with medicine-wrapping paper in the same manner as in Example 1, the surface was observed with a polarizing microscope, and no defects were generated.

[Example 4]
A polarizer was produced in the same manner as in Example 3 except that the amount of the 50% aqueous solution of polyacrylamide was changed to 800 parts by mass. In addition, since 800 mass parts of 50% aqueous solution of polyacrylamide was mixed, the amount of polyacrylamide is 400 mass parts.

The thickness of the polarizer of Example 4 was 0.4 μm. The polarization degree of the polarizer was 86%.
When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, after the surface of this polarizer was rubbed with medicine-wrapping paper in the same manner as in Example 1, the surface was observed with a polarizing microscope, and no defects were generated.

[Comparative Example 2]
A polarizer was produced in the same manner as in Example 3 except that a 50% aqueous solution of polyacrylamide was not added.
The thickness of the polarizer of Comparative Example 2 was 0.4 μm. The polarization degree of the polarizer was 98%.
When the surface of the polarizer was observed with a polarizing microscope, there were no defects.
Next, the surface of this polarizer was rubbed with a medicine-wrapping paper in the same manner as in Example 1, and then the surface was observed with a polarizing microscope. As a result, the anisotropy of the polarizer disappeared, and Defects (innumerable scratches) occurred.

The polarizer of the present invention can be used for, for example, a constituent member of a liquid crystal display device, polarized sunglasses, and the like.
The method for producing a polarizer of the present invention can easily produce a polarizer excellent in scratch resistance.

Claims (6)

A polarizer comprising an azobenzene compound represented by the following general formula (I) and polyacrylamide.

R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a substituted or unsubstituted arylene group, and R ₃ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, substituted or unsubstituted A substituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, or a group represented by the following general formula (II) is represented, M represents a counter ion, m represents 1 or 2 N represents an integer of 1 to 3.

X represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms (including an alkyl group in which non-adjacent carbon atoms are substituted with oxygen atoms), a methacryl group, or an acrylic group.   The polarizer according to claim 1, wherein the polyacrylamide is contained in an amount of 25 to 900 parts by mass with respect to 100 parts by mass of the azobenzene compound.   The polarizer of Claim 1 or 2 in which the said polyacrylamide contains nonionic polyacrylamide.   The polarizer according to claim 1, wherein the azobenzene compound has water solubility.   The image display apparatus which has a polarizer in any one of Claims 1-4. The manufacturing method of a polarizer which has the process of coating the coating liquid containing the azobenzene compound represented by the following general formula (I), polyacrylamide, and an aqueous solvent on a base material.

R ₁ represents a substituted or unsubstituted aryl group, R ₂ represents a substituted or unsubstituted arylene group, and R ₃ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, substituted or unsubstituted A substituted acetyl group, a substituted or unsubstituted benzoyl group, a substituted or unsubstituted phenyl group, or a group represented by the following general formula (II) is represented, M represents a counter ion, m represents 1 or 2 N represents an integer of 1 to 3.

X represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms (including an alkyl group in which non-adjacent carbon atoms are substituted with oxygen atoms), a methacryl group, or an acrylic group.

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