JP2008233607A - Polarizing plate and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate having excellent polarization properties in a wide band and excellent light resistance and to provide a method for efficiently manufacturing the polarizing plate. <P>SOLUTION: The polarizing plate includes anisotropic metal nanoparticles formed by reducing metal ions by irradiation with light in its heated state in a resin matrix. Preferably, the heating is performed at ≥40°C, the resin matrix is a stretched resin film, an average aspect ratio of the anisotropic metal nanoparticles is ≥1.5 and a long axis of the anisotropic metal nanoparticle is oriented in the stretched direction of the resin film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarizing plate having excellent polarization in a wide band and excellent in light resistance and a method for efficiently producing the polarizing plate.

  Conventionally, as a method for producing a polarizing plate containing anisotropic metal nanoparticles as a ligand, metal compound nanoparticles are dispersed in glass and uniaxially stretched at a temperature equal to or higher than the glass softening temperature. A method has been proposed in which anisotropic metal nanoparticles are formed by anisotropy and further reduction with heat or hydrogen gas to produce a polarizing plate (see Patent Document 1). In this proposal, since the stretch ratio of the glass is large, it is possible to produce a polarizing plate with a high degree of orientation. However, high heat above the glass softening temperature is required in the production process, and if the film is not thick to some extent, handling is difficult, so thinning is difficult. Furthermore, there is a problem that glass is easily broken during handling.

  Therefore, by changing the matrix from glass to organic polymer, as an invention to improve the above-mentioned handling problems, applying a solution mixed with polyamic acid and metal salt, applying heat in a stretched state, and polyimideizing A method has been proposed in which metal ions are reduced by simultaneous thermal reduction to form anisotropic metal nanoparticles (see Patent Document 2 and Patent Document 3). According to these proposals, since polyamide has high orientation and heat resistance, a polarizing plate with a high degree of orientation can be produced. However, the polyamidation step requires a high temperature of 300 ° C. or higher, and the manufacturing apparatus becomes complicated and large in size accompanying such high temperature treatment. In addition, since high heat is applied, there is a problem that even after the particles grow into a rod shape, they are easily deformed into a spherical shape by heat, and it is difficult to control the aspect ratio. Furthermore, there is a problem that the band showing the polarization property of the obtained polarizing plate is narrow.

In addition, there has been proposed a method of forming metal particles by mixing polyvinyl alcohol and a metal salt, stretching a film formed, and aligning polymer chains to reduce metal ions by light irradiation (see FIG. (See Patent Document 4).
However, it is difficult to control and grow metal particles in a rod shape, and the obtained polarizing plate has a narrow band of polarization, and photoreduction alone causes reduction reaction of metal ions and reduction of metal atoms. There is a problem that micronization is slow and it cannot be efficiently produced.

JP 2003-29749 A JP-A-8-184701 JP 2006-184624 A JP 2006-249421 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, an object of the present invention is to provide a polarizing plate having excellent polarization in a wide band and excellent in light resistance and a method for efficiently producing the polarizing plate.

Means for solving the problems are as follows. That is,
<1> A polarizing plate characterized by containing anisotropic metal nanoparticles obtained by reducing metal ions by light irradiation in a heated state in a resin matrix.
In the polarizing plate described in <1>, the resin matrix includes anisotropic metal nanoparticles obtained by reducing metal ions by light irradiation in a heated state. The anisotropic metal nanoparticles exhibit surface plasmon resonance, exhibit polarization properties due to the difference in absorption wavelength between the short axis and the long axis, have excellent polarization properties particularly in a wide band, and improve light resistance.
<2> The polarizing plate according to <1>, wherein the heating temperature is 40 ° C. or higher.
<3> The polarizing plate according to any one of <1> to <2>, wherein the resin matrix is a stretched resin film.
<4> From the above <1>, the average value of the aspect ratio of the anisotropic metal nanoparticles is 1.5 or more, and the long axis of the anisotropic metal nanoparticles is oriented in the stretching direction of the resin film <3> A polarizing plate according to any one of the above.
<5> The above <1> to <4, wherein the anisotropic metal nanoparticles include at least one selected from silver, gold, copper, aluminum, palladium, rhodium, platinum, ruthenium, selenium, cobalt, iron, and nickel. > It is a polarizing plate in any one of.
<6> A stretching step of stretching a resin film containing at least metal ions;
And a reduction step of forming anisotropic metal nanoparticles by reducing the metal ions by irradiating the stretched resin film with light in a heated state.
In the method for producing a polarizing plate according to <6>, a resin film containing at least metal ions is stretched in the stretching step. Next, the resin film stretched in the light irradiation step is irradiated with light in a heated state to reduce at least metal ions to form anisotropic metal nanoparticles composed of at least one kind of metal. As a result, it is possible to efficiently produce a polarizing plate having excellent polarization in a wide band and excellent light resistance.
<7> The method for producing a polarizing plate according to <6>, wherein the resin film is formed by forming a resin composition containing at least a metal ion.
<8> The method for producing a polarizing plate according to <6>, wherein the resin film containing at least metal ions is impregnated with at least metal ions in the resin film.

  According to the present invention, a conventional problem can be solved, and a polarizing plate having excellent polarization in a wide band and excellent in light resistance and a method for efficiently producing the polarizing plate can be provided.

(Polarizer)
The polarizing plate of the present invention contains anisotropic metal nanoparticles obtained by reducing metal ions by light irradiation in a heated state in a resin matrix, and includes a shape control agent, seed particles, a crosslinking agent, and further if necessary. It contains other components.
Here, in the present invention, heating means a temperature exceeding room temperature (20 ° C. to 25 ° C.), and preferably 40 ° C. or higher.

<Resin matrix>
The resin matrix serves as a place for forming anisotropic metal nanoparticles from at least metal ions, and is preferably, for example, a stretched resin film.

-Resin film-
There is no restriction | limiting in particular as resin in the said resin film, Although it can select suitably according to the objective, A water-soluble polymer and a polymer soluble in an organic solvent are suitable.
Examples of the water-soluble polymer include polyvinyl alcohol, polymethacrylic acid, and polyacrylic acid. Among these, polyvinyl alcohol is particularly preferable.
Examples of the polymer soluble in the organic solvent include polyvinyl butyral, polymethyl methacrylate, polyvinyl formal, polycarbonate, cellulose butyrate, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene adipamide, polyvinyl chloride, Examples thereof include vinyl acetate, and copolymers thereof (for example, vinyl chloride-vinyl acetate copolymer, styrene-methyl methacrylate copolymer). Among these, polyvinyl butyral, polymethyl methacrylate, polycarbonate, polystyrene, cellulose acetate, polyvinyl chloride, and polyvinyl acetate are particularly preferable.

  The resin film is preferably stretched under stress. By this stretching, an alignment field in which polymer chains are aligned is formed. Examples of the stretching include a heating stretching method, a humidity conditioning stretching method, a heating stretching method under humidity conditioning, and the like, and the heating stretching method is preferable.

<Metal ion>
The metal ion is preferably at least one ion selected from silver, gold, copper, aluminum, palladium, rhodium, platinum, ruthenium, selenium, tellurium, cobalt, iron and nickel. Among these, gold, silver, and copper ions are particularly preferable.
As the metal ion source in the metal ion, for example, a metal compound is suitable.
Examples of the metal compound include metal salts, metal complexes, and organometallic compounds.

The acid that forms the metal salt may be either an inorganic acid or an organic acid.
There is no restriction | limiting in particular as said inorganic acid, According to the objective, it can select suitably, For example, nitric acid; Hydrohalic acids, such as hydrochloric acid, hydrobromic acid, hydroiodic acid, etc. are mentioned.
There is no restriction | limiting in particular as said organic acid, According to the objective, it can select suitably, For example, carboxylic acid, a sulfonic acid, etc. are mentioned.
Examples of the carboxylic acid include acetic acid, butyric acid, oxalic acid, stearic acid, behenic acid, lauric acid, benzoic acid and the like.
Examples of the sulfonic acid include methyl sulfonic acid.

There is no restriction | limiting in particular as a chelating agent which forms the said metal complex, According to the objective, it can select suitably, For example, acetylacetonate, EDTA, etc. are mentioned. Moreover, you may form a complex with said metal salt and a ligand, As this ligand, an imidazole, a pyridine, phenylmethyl sulfide etc. are mentioned, for example.
The metal compound includes an acid of a metal ion halide complex (for example, chloroauric acid, chloroplatinic acid and the like) and an alkali metal salt (for example, sodium chloroaurate and sodium tetrachloropalladate).

-Anisotropic metal nanoparticles-
The anisotropic metal nanoparticles are nano-sized rod-shaped metal fine particles having a size of several nanometers to 100 nm formed by reducing the metal ions by light irradiation. The rod-shaped metal fine particles mean particles having an average aspect ratio (major axis length / minor axis length) of 1.5 or more.
The average aspect ratio of the anisotropic metal nanoparticles is 1.5 or more, preferably 1.6 or more, and more preferably 2.0 or more. If the average aspect ratio is less than 1.5, sufficient anisotropic absorption characteristics may not be obtained.
Here, the aspect ratio of the anisotropic metal nanoparticles is measured by measuring the major axis length and minor axis length of the anisotropic metal nanoparticles, and expressed by the following formula: (major axis length of anisotropic metal nanoparticles) ) / (Short axis length of anisotropic metal nanoparticles).
The short axis length of the anisotropic metal nanoparticles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1 nm to 50 nm, and more preferably 5 nm to 30 nm. The major axis length of the anisotropic metal nanoparticles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 200 nm.

Such anisotropic metal nanoparticles exhibit surface plasmon resonance and absorb in the ultraviolet to infrared region. For example, anisotropic metal nanoparticles having a minor axis length of 1 nm to 50 nm, a major axis length of 10 nm to 1000 nm, and an aspect ratio of 1.5 or more have different absorption positions between the minor axis direction and the major axis direction. Therefore, a film in which such anisotropic metal nanoparticles are oriented exhibits anisotropic absorption and is used as a polarizing plate.
Here, FIG. 1 shows an absorption spectrum of anisotropic metal nanoparticles having a minor axis length of 12.4 nm and a major axis length of 45.5 nm. The absorption of the short axis of such anisotropic metal nanoparticles is around 530 nm and shows red, and the absorption of the long axis of anisotropic metal nanoparticles is around 780 nm and shows dark blue.

  As the anisotropic metal nanoparticles, there is no particular limitation on the shape as long as dichroism is manifested. Besides the rod shape as shown in FIG. 2A, a cylindrical shape, a quadrangular prism shape, a triangular prism shape, a hexagonal prism shape, a dogbone shape It may be. Moreover, the aggregate which consists of two or more substantially spherical metal nanoparticles may be sufficient, and as shown to FIG. 2B, the aggregate which consists of two or more substantially spherical metal nanoparticles is two or more substantially spherical metal nanoparticles. The metal nanoparticle means a particle in a state satisfying the following formula: distance between metal nanoparticle and metal nanoparticle (L1) ≦ metal nanoparticle diameter (L2).

  The anisotropic metal nanoparticles are made of at least one metal, for example, at least one selected from silver, gold, copper, aluminum, palladium, rhodium, platinum, ruthenium, selenium, cobalt, tellurium, iron and nickel. It is preferable that an element is included. Among these, gold, silver, and copper are particularly preferable.

-Form control agent-
The form control agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include nitrogen-containing heterocyclic compounds, quaternary ammonium salts, primary amines, secondary amines, tertiary amines, mercapto compounds, and the like. Preferably mentioned.
There is no restriction | limiting in particular as said nitrogen-containing heterocyclic compound, According to the objective, it can select suitably, For example, the compound etc. which are described in Unexamined-Japanese-Patent No. 2006-28492 Paragraph Nos. [0028]-[0061] Is mentioned.
Examples of the quaternary ammonium salt include cetyltrimethylammonium bromide and dodecyltrimethylammonium bromide, which are long-chain alkyl quaternary ammonium salts.
The content of the form control agent in the polarizing plate is preferably 1 ppm to 5.0 mass%, more preferably 5 ppm to 1.0 mass%.

-Seed particles-
The resin matrix film containing metal ions may contain metal fine particles having a diameter of 10 nm or less as required. The metal fine particles serve as crystal nuclei when the metal ions are reduced to form anisotropic metal nanoparticles, and can be efficiently anisotropically grown. Examples of the metal species of the metal fine particles serving as crystal nuclei include platinum, gold, and silver.

-Crosslinking agent-
The resin matrix film containing a metal ion, like a boric acid compound with respect to polyvinyl alcohol, may further improve the orientation of the resin matrix alignment field, and if necessary, a crosslinking agent may be added to crosslink the resin matrix. Good. Preferred examples of the boric acid compound include boric acid and diphenyl boric acid.

-Reduction-
The reduction is performed by light irradiation in a heated state. The heating temperature is preferably 40 ° C. or higher, and more preferably 50 ° C. or higher. When the heating temperature is less than 40 ° C., the particle formation rate is slow, and residual metal ions may be reduced over time, resulting in a change in hue. The details of the light irradiation will be described in detail in a polarizing plate manufacturing method described later.
The polarizing plate exhibits a growth promoting effect by adding a reducing aid as required. There is no restriction | limiting in particular as said reduction adjuvant, According to the objective, it can select suitably, For example, ascorbic acid, a citric acid, an amine compound, a thiol compound etc. are mentioned.

  As described above, the polarizing plate of the present invention includes anisotropic metal nanoparticles that are reduced by light irradiation in a resin matrix in a state where metal ions are heated, and the anisotropic metal nanoparticles are resin. The film is oriented in the stretching direction of the film, and can be efficiently produced by the method for producing a polarizing plate of the present invention described below.

(Production method of polarizing plate)
The method for producing a polarizing plate of the present invention includes at least a stretching step and a light irradiation step, and further includes other steps as necessary.

-Stretching process-
The stretching step is a step of stretching a resin film containing at least metal ions.
Examples of the resin film containing at least metal ions include (1) those obtained by forming a resin composition containing at least metal ions, and (2) those obtained by impregnating a resin film with at least metal ions. .

There is no restriction | limiting in particular as the film-forming method of the resin film of said (1), According to the objective, it can select suitably, For example, the resin composition containing a metal ion, resin, and a solvent is apply | coated on a base material. And dried to form a resin film.
As the resin and metal ions, those described above can be used.
The said metal ion is normally mix | blended with the form of a metal compound, and the compounding quantity has preferable 0.1-3 mass parts with respect to 100 mass parts of resin.

The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, water, methanol, ethanol, n-propanol, isopropanol, t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol Alcohol solvents such as ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol; acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, cyclopentanone, Ketone solvents such as 2-pyrrolidone and N-methyl-2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as dimethylformamide and dimethylacetamide Nitrile solvents such as acetonitrile and butyronitrile; ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane; chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, etc. Halogenated hydrocarbons; phenols such as phenol, p-chlorophenol, o-chlorophenol, m-cresol, o-cresol, p-cresol; benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, etc. And aromatic hydrocarbons such as carbon disulfide, ethyl cellosolve, and butyl cellosolve. These may be used individually by 1 type and may use 2 or more types together.
Examples of the coating method include spin coating, casting, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing.

The shape, structure, size and the like of the substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a plate shape and a sheet shape. The structure may be, for example, a single layer structure or a laminated structure, and can be appropriately selected.
There is no restriction | limiting in particular as a material of the said base material, Any of an inorganic material and an organic material can be used conveniently.
Examples of the inorganic material include glass, quartz, and silicon.
Examples of the organic material include acetate resins such as triacetyl cellulose (TAC); polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, Examples thereof include acrylic resins, polynorbornene resins, cellulose resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl chloride resins, polyvinylidene chloride resins, and polyacryl resins. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the impregnation method (2) include a method of immersing a resin film in a liquid containing at least metal ions. In addition, at the time of immersion, it is preferable to swell the resin film in a solvent beforehand.

Next, the produced resin film containing at least metal ions is stretched. The stretching is preferably uniaxial stretching under stress. Examples of the stretching include a heating stretching method, a humidity conditioning stretching method, and a heating stretching method under humidity conditioning, and the heating stretching method is particularly preferable.
There is no restriction | limiting in particular as a draw ratio, According to the objective, it can select suitably, 1.5 times-20 times are preferable, and 3 times-10 times are more preferable.
In the case of the heating stretching method, the heating temperature is preferably heated to a temperature equal to or higher than the glass transition temperature (Tg) of the resin film.

-Reduction process-
The reduction process is a process in which the stretched resin film is irradiated with light to reduce metal ions to form anisotropic metal nanoparticles.

The heating temperature is preferably 40 ° C. or higher, and more preferably 50 ° C. or higher. By irradiating with light in a heated state, the formation speed of metal fine particles is improved, and a polarizing plate can be produced efficiently.
Examples of the light in the light irradiation include visible light, ultraviolet light, near infrared light, X-rays, and electron beams. Among these, ultraviolet light is particularly preferable.
There is no restriction | limiting in particular as conditions for the said ultraviolet light irradiation, According to the objective, it can select suitably, For example, as for the wavelength of the ultraviolet light to irradiate, 160 nm-380 nm are preferable, and 250 nm-380 nm are more preferable. The irradiation energy is preferably 1 to 10,000 mW / cm ² and the irradiation time is preferably 1 second to 600 minutes.
Examples of the ultraviolet light source include low-pressure mercury lamps (sterilization lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), and short arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, Mercury xenon lamp).
Further, the irradiated light may be polarized light. The polarized light is preferably linearly polarized light.
For the polarized light irradiation, a general method, for example, a method using the light source and various polarizing plates such as iodine, a dichroic dye, a wire grid, a method using a polarized light transmission filter using a Brewster angle, a Gran-Thomson prism Or a method using a laser beam having polarization.

Here, FIG. 3 (A) to FIG. 3 (D) are process diagrams showing an example of a method for producing a polarizing plate of the present invention.
First, as shown in FIG. 3A, a resin film 1 containing at least metal ions 2 is formed. The resin film containing at least metal ions may be formed by forming a resin composition containing at least metal ions, or may be formed by impregnating at least metal ions in a resin film.
Next, as shown in FIG. 3B, the produced resin film 1 is uniaxially stretched to form an alignment field of polymer chains along the stretching direction, and metal ions 2 are contained in the alignment field. ing.
Next, as shown in FIG. 3C, the stretched resin film 1 ′ is irradiated with light, whereby the metal ions are reduced and the crystal nuclei 3 of anisotropic metal nanoparticles are formed.
Next, as shown in FIG. 3 (D), the crystal nuclei 3 of anisotropic metal nanoparticles grow along the orientation field by irradiation with light in a further heated state, and at least an anisotropy made of metal. Metal nanoparticles 4 are formed.

The polarizing plate of the present invention includes anisotropic metal nanoparticles having an average aspect ratio of 1.5 or more, and the long axis of the anisotropic metal nanoparticles is oriented in the stretching direction of the resin film, It has excellent polarization.
Here, it can confirm that the said anisotropic metal nanoparticle has orientated in the extending | stretching method by observing the cross section of a polarizing plate with a transmission electron microscope (TEM), for example.

-Applications-
The polarizing plate of the present invention can be applied to, for example, a projector, a liquid crystal monitor, a liquid crystal television and the like, and further, glass for various vehicles such as an optical isolator, an optical fiber, an automobile, a bus, a truck, a train, a bullet train, an airplane, a passenger plane, and a ship. It can be widely used in various fields such as general detached houses, apartment houses, office screws, stores, public facilities, factory openings such as buildings, and glass for building materials such as partitions.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
-Production of polarizing plates containing anisotropic silver nanoparticles by photoreduction-
(1) Production of silver nitrate-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Subsequently, it was immersed in 5.0 mass% aqueous solution of silver nitrate (manufactured by Kanto Chemical Co., Ltd.) for 30 seconds, a film was set on a uniaxial stretching machine, and stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig. Further, since silver nitrate is easily reduced by ultraviolet light, sample preparation was performed under a yellow light with ultraviolet light cut, and the sample was stored in a light-shielding bag.

(2) Preparation of anisotropic silver nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a constant temperature bath at 40 ° C. while maintaining the orientation by fixing the stretched thin film obtained above to a jig. As a result of forming silver nanoparticles, a film exhibiting brown color was obtained.

  When the slice of the obtained polarizing plate of Example 1 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), Ag nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of the Ag nanoparticles was 1.5.

(Example 2)
-Production of polarizing plates containing anisotropic silver nanoparticles by photoreduction-
(1) Production of silver nitrate-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Subsequently, it was immersed in 5.0 mass% aqueous solution of silver nitrate (manufactured by Kanto Chemical Co., Ltd.) for 30 seconds, a film was set on a uniaxial stretching machine, and stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig. Further, since silver nitrate is easily reduced by ultraviolet light, sample preparation was performed under a yellow light with ultraviolet light cut, and the sample was stored in a light-shielding bag.

(2) Preparation of anisotropic silver nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a constant temperature bath at 60 ° C. with the stretched thin film obtained above fixed to a jig and maintained in orientation. As a result of forming silver nanoparticles, a film exhibiting brown color was obtained.

  When the slice of the obtained polarizing plate of Example 2 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Ag nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of the Ag nanoparticles was 1.8.

(Example 3)
-Production of polarizing plates containing anisotropic silver nanoparticles by photoreduction-
(1) Production of silver nitrate-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Subsequently, it was immersed in 5.0 mass% aqueous solution of silver nitrate (manufactured by Kanto Chemical Co., Ltd.) for 30 seconds, a film was set on a uniaxial stretching machine, and stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig. Further, since silver nitrate is easily reduced by ultraviolet light, sample preparation was performed under a yellow light with ultraviolet light cut, and the sample was stored in a light-shielding bag.

(2) Preparation of anisotropic silver nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a thermostatic bath at 80 ° C. while maintaining the orientation by fixing the stretched thin film obtained above to a jig. As a result of forming silver nanoparticles, a film exhibiting brown color was obtained.

  When the slice of the obtained polarizing plate of Example 3 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Ag nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of the Ag nanoparticles was 2.5.

Example 4
-Production of polarizing plates containing anisotropic gold nanoparticles by photoreduction-
(1) Preparation of chloroauric acid-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Next, it is immersed in a 5.0% by mass aqueous solution of chloroauric acid (manufactured by Kanto Chemical Co., Inc.) for 30 seconds. did. Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig.

(2) Preparation of anisotropic gold nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a constant temperature bath at 40 ° C. with the stretched thin film obtained above fixed to a jig and maintained in orientation. As a result of forming gold nanoparticles, a film exhibiting red-black color was obtained.

  When the slice of the obtained polarizing plate of Example 4 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Au nanoparticles were parallel to the film stretching direction and the film It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of the Au nanoparticles was 1.5.

(Example 5)
-Production of polarizing plates containing anisotropic gold nanoparticles by photoreduction-
(1) Preparation of chloroauric acid-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Next, it was immersed in a 5.0% by mass aqueous solution of chloroauric acid (manufactured by Kanto Chemical Co., Inc.) for 30 seconds, a uniaxial stretching machine film was set, and the film was stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). . Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig.

(2) Preparation of anisotropic gold nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a constant temperature bath at 60 ° C. with the stretched thin film obtained above fixed to a jig and maintained in orientation. As a result of forming gold nanoparticles, a film exhibiting red-black color was obtained.

  When the section of the obtained polarizing plate of Example 5 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Au nanoparticles were parallel to the film stretching direction and the film It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of Au nanoparticles was 1.7.

(Example 6)
-Production of polarizing plates containing anisotropic gold nanoparticles by photoreduction-
(1) Preparation of chloroauric acid-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Next, it is immersed in a 5.0% by mass aqueous solution of chloroauric acid (manufactured by Kanto Chemical Co., Inc.) for 30 seconds. did. Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig.

(2) Production of anisotropic gold nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a constant temperature bath at 80 ° C. with the stretched thin film obtained above fixed to a jig and maintained in orientation. As a result of forming gold nanoparticles, a film exhibiting red-black color was obtained.

  When the slice of the obtained polarizing plate of Example 6 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Au nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. The average aspect ratio (major axis length / minor axis length) of the Au nanoparticles was 2.3.

(Comparative Example 1)
-Production of polarizing plates containing anisotropic silver nanoparticles by photoreduction-
(1) Production of silver nitrate-containing polymer film A PVA film (Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Subsequently, it was immersed in 5.0 mass% aqueous solution of silver nitrate (manufactured by Kanto Chemical Co., Ltd.) for 30 seconds, a film was set on a uniaxial stretching machine, and stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig. Further, since silver nitrate is easily reduced by ultraviolet light, sample preparation was performed under a yellow light with ultraviolet light cut, and the sample was stored in a light-shielding bag.

(2) Preparation of anisotropic silver nanoparticle-containing polymer film by photoreduction In the state where the stretched thin film obtained in (1) above is fixed to a jig and the orientation is maintained, UV light irradiation (36 mW in a thermostatic bath at 25 ° C. / Cm ² , 2 minutes), and as a result of forming silver nanoparticles, a film having a light brown color was obtained.

  When the slice of the obtained polarizing plate of Comparative Example 1 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), Ag nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. Moreover, the average value of the aspect ratio (major axis length / minor axis length) of the Ag nanoparticles was 1.0.

(Comparative Example 2)
-Production of anisotropic gold nanoparticle-containing polarizing plate by photoreduction (1) Production of chloroauric acid-containing polymer film A PVA film (manufactured by Kuraray Co., Ltd., polyvinyl alcohol film) was immersed in pure water for 60 seconds to swell. Next, it is immersed in a 5.0% by mass aqueous solution of chloroauric acid (manufactured by Kanto Chemical Co., Inc.) for 30 seconds, a film is set on a uniaxial stretching machine, and stretched up to 5 times under high temperature and high humidity (60 ° C., 90% RH). did. Furthermore, by drying at 70 ° C. for 4 minutes, a polymer film containing silver nitrate and having a polymer chain stretched and oriented was obtained. It should be noted that the orientation state was not broken by fixing the stretched state with a jig.

(2) Production of anisotropic gold nanoparticle-containing polymer film by photoreduction UV irradiation (36 mW / cm ²⁾ in a thermostatic chamber at 25 ° C. while maintaining the orientation by fixing the stretched thin film obtained above to a jig. As a result of forming gold nanoparticles, a film exhibiting red-black color was obtained.

  When the slice of the obtained polarizing plate of Comparative Example 2 was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), the Au nanoparticles were parallel to the stretching direction of the film, and It was oriented in a substantially horizontal direction with respect to the horizontal plane. The average value of the aspect ratio (major axis length / minor axis length) of the Au nanoparticles was 1.1.

(Comparative Example 3)
A commercially available iodine / PVA polarizing plate (manufactured by Sanlitz) was prepared.

<Evaluation of polarizing properties of polarizing plate>
About each produced polarizing plate of Examples 1-6 and Comparative Examples 1-3, the polarization | polarized-light transmission of each polarizing plate using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation make, V-570). The spectrum was measured. Polarization is achieved by installing a visible to near-infrared Glan-Taylor polarizer sold by JASCO Corporation as a window plate and each of the polarizers, and rotating the Glan-Taylor polarizer to change the incident polarization plane. A polarized light transmission spectrum (MD spectrum) when parallel to the alignment direction of the polarizing plate and a polarized light transmission spectrum (TD spectrum) when perpendicular to the alignment direction of the polarizing plate are measured, and the extinction ratio is obtained by the following formula 1. It was. The results are shown in Table 1.
<Formula 1>
Extinction ratio (dB) = 10 × log (T _max / T _min )
In Equation 1, T _max represents the transmittance obtained from the TD spectrum, and T _min represents the transmittance obtained from the MD spectrum.

<Evaluation of weather resistance>
A weather resistance test was conducted using a sunshine weather meter (manufactured by Suga Test Instruments Co., Ltd.), and the weather resistance was evaluated by the change in the extinction ratio after 1,000 hours. The results are shown in Table 1.

  Since the polarizing plate of the present invention has excellent polarization in a wide band and excellent light resistance, it can be applied to, for example, a projector, a liquid crystal monitor, a liquid crystal television, etc., but further, an optical isolator, an optical fiber, an automobile, Glasses for various vehicles such as buses, trucks, trains, bullet trains, airplanes, passenger planes, ships, etc .; building materials such as general detached houses, apartment houses, office services, stores, public facilities, factory facilities, etc. It can be widely used in various fields such as industrial glass.

FIG. 1 is a diagram showing an absorption spectrum of anisotropic metal nanoparticles. FIG. 2A is a schematic view showing rod-shaped anisotropic metal nanoparticles. FIG. 2B is a schematic diagram showing substantially spherical anisotropic metal nanoparticles in an aggregated state. FIG. 3 is a process diagram showing an example of a method for producing a polarizing plate of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin film 1 'Resin film after extending | stretching 2 Metal ion 3 Crystal nucleus of anisotropic metal nanoparticle 4 Anisotropic metal nanoparticle

Claims (8)

  A polarizing plate comprising an anisotropic metal nanoparticle formed by reducing metal ions by light irradiation in a heated state in a resin matrix.   The polarizing plate according to claim 1, wherein the heating temperature is 40 ° C. or higher.   The polarizing plate according to claim 1, wherein the resin matrix is a stretched resin film.   The average value of the aspect ratio of the anisotropic metal nanoparticles is 1.5 or more, and the major axis of the anisotropic metal nanoparticles is oriented in the stretching direction of the resin film. The polarizing plate as described in.   5. The anisotropic metal nanoparticle according to claim 1, comprising at least one selected from silver, gold, copper, aluminum, palladium, rhodium, platinum, ruthenium, selenium, cobalt, iron, and nickel. Polarizing plate. A stretching step of stretching a resin film containing at least metal ions;
A reduction step of irradiating the stretched resin film with light to reduce metal ions to form anisotropic metal nanoparticles.   The method for producing a polarizing plate according to claim 6, wherein the resin film is formed by forming a resin composition containing at least metal ions.   The method for producing a polarizing plate according to claim 6, wherein the resin film containing at least metal ions is obtained by impregnating the resin film with at least metal ions.