JP2008102245A - Method of manufacturing anisotropic absorbing film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an anisotropic absorbing film for efficiently manufacturing the anisotropy absorption film superior in light resistance by orienting the anisotropy absorption material without lowering density in the same plane. <P>SOLUTION: The method of manufacturing the anisotropic absorbing film includes: an application layer forming process for forming an application layer by applying and drying anisotropy absorption film application liquid containing at least an ultraviolet curing liquid crystal compound, a photoinitiator, and the anisotropy absorption material of 1.5 or more of an average value of an aspect ratio on a base material having an orientation layer on a surface; and a curing process for orienting an inclined angle to a base material face of a long axis of the anisotropy absorption material 0 degrees or more and 70 degrees or less by curing with irradiation with an ultraviolet ray in a state where the application layer is heated up to a temperature in which a liquid crystal phase expresses. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention makes it possible to incline an anisotropic absorption material at a certain angle without reducing the density in the same plane, and efficiently manufacture an anisotropic absorption film that is excellent in light resistance and suitable as an absorption polarizer. The present invention relates to a method for producing an anisotropic absorption film.

  Nano-size anisotropic absorbing materials are attracting attention because of their optical properties and magnetic and conductive anisotropy. Examples of such anisotropic absorption materials include gold and silver anisotropic metal nanoparticles exhibiting surface plasmon resonance, carbon nanotubes, and the like, and they are used as absorption polarizers in which these are oriented. .

  The absorption type polarizer applies a coating solution containing an anisotropic absorbing material on a substrate, aligns it, and fixes it by ultraviolet (UV) irradiation, so that an expensive film forming machine is not required and the area can be increased. Easy. Further, since the substrate is not exposed to a high temperature unlike vapor deposition, not only an inorganic material such as glass or a polyimide having high heat resistance, but also a low-cost and highly transparent polymer film can be used.

  Moreover, as a uniaxial orientation method of anisotropic absorbent material, a method of orientation by stretching a material obtained by kneading the anisotropic absorbent material in a polymer is disclosed (see Non-Patent Documents 1 and 2). However, in the methods described in these documents, there is a problem that, by stretching, the density in the same plane of the anisotropic absorbent material is lowered and the degree of orientation is not increased. In addition, a film forming method using the Langmuir-Blodget (LB) method has also been reported (see Non-Patent Document 3). However, the film formation by the LB method takes time and has a drawback that it is difficult to increase the area.

In addition, a carbon nanotube alignment method using liquid crystal has been proposed (see Non-Patent Document 4). However, this method has a problem that the liquid crystal molecules used are not UV curable and the orientation of the carbon nanotubes cannot be fixed.
Patent Document 1 proposes an optically anisotropic film that includes an optically anisotropic material having an aspect ratio of 2 or more in a lyotropic liquid crystal and in which the lyotropic liquid crystal and the optically anisotropic material are aligned. However, the present situation is that further development of a technique for satisfactorily arranging optically anisotropic materials is desired.

JP 2002-294239 A S. Matsuda et al., Jpn. J. et al. Appl. Phy. 2005, 44, p187 Y. Koike et al., Macromolecules, 2004, 37 (22), p8342-8348. F. Kim et al. Am. Chem. Soc. 2001, 123, p4360-4361. I. Dierking et al., Adv. Mater. , 2004, 16 (11), p865-869

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, according to the present invention, the anisotropic absorbing material can be inclined at a certain angle without reducing the density in the same plane, and the anisotropic absorbing film excellent in light resistance and suitable as an absorbing polarizer can be efficiently used. It is an object of the present invention to provide a method for manufacturing an anisotropic absorption film that can be manufactured well.

Means for solving the problems are as follows. That is,
<1> An anisotropic absorption containing at least an ultraviolet curable liquid crystal compound, a photopolymerization initiator, and an anisotropic absorbing material having an average aspect ratio of 1.5 or more on a substrate having an alignment film on the surface. A coating layer forming step of applying a film coating solution and drying to form a coating layer;
The coating layer is heated to a temperature at which a liquid crystal phase is expressed and cured by irradiating with ultraviolet rays, so that the inclination angle of the long axis of the anisotropic absorbent material with respect to the substrate surface is aligned between 0 degree and 70 degrees. A method for producing an anisotropic absorption film comprising a curing step.
<2> The method for producing an anisotropic absorption film according to <1>, wherein the ultraviolet curable liquid crystal compound is a thermotropic liquid crystal compound.
<3> The method for producing an anisotropic absorbent film according to any one of <1> to <2>, wherein the anisotropic absorbent film coating solution contains a polymer surfactant.
<4> The method for producing an anisotropic absorption film according to any one of <1> to <3>, wherein the anisotropic absorption material contains any one of anisotropic metal nanoparticles and carbon nanotubes.
<5> The method for producing an anisotropic absorption film according to <4>, wherein the anisotropic metal nanoparticles include at least one selected from gold, silver, copper, and aluminum.

  The manufacturing method of the anisotropic absorption film of the present invention includes a coating layer forming step and a curing step. The coating layer forming step includes at least an ultraviolet curable liquid crystal compound, a photopolymerization initiator, and an anisotropic absorbing material having an average aspect ratio of 1.5 or more on a substrate having an alignment film on the surface. In this step, an anisotropic absorption film coating solution is applied and dried to form a coating layer. In the curing step, the coating layer is cured by irradiating with ultraviolet rays in a state where the coating layer is heated to a temperature at which a liquid crystal phase develops, and the inclination angle of the long axis of the anisotropic absorbent material with respect to the substrate surface is 0 degree or more. This is a step of aligning to 70 degrees or less. As a result, in the method for producing an anisotropic absorption film of the present invention, the anisotropic absorption material can be inclined at a certain angle without lowering the density in the same plane, has excellent light resistance, and absorbs polarized light. An anisotropic absorption film suitable as a child can be efficiently produced.

  According to the present invention, the conventional problems can be solved, the anisotropic absorbing material can be inclined at a certain angle without lowering the density in the same plane, excellent in light resistance, and as an absorbing polarizer. The manufacturing method of the anisotropic absorption film which can manufacture a suitable anisotropic absorption film efficiently can be provided.

  The method for producing an anisotropic absorption film of the present invention includes at least a coating layer forming step and a curing step, and further includes other steps as necessary.

<Coating layer formation process>
The coating layer forming step includes at least an ultraviolet curable liquid crystal compound, a photopolymerization initiator, and an anisotropic absorbing material having an average aspect ratio of 1.5 or more on a substrate having an alignment film on the surface. In this step, an anisotropic absorption film coating solution is applied and dried to form a coating layer.

-Base material-
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.

The base material may be appropriately synthesized or a commercially available product may be used.
There is no restriction | limiting in particular as thickness of the said base material, According to the objective, it can select suitably, 10-2,000 micrometers is preferable and 50-500 micrometers is more preferable.

-Alignment film-
As the alignment film, an alignment film by rubbing treatment is suitable. In the rubbing treatment, a film made of, for example, polyimide, polyamideimide, polyetherimide, polyvinyl alcohol or the like is laminated on the surface of the substrate, and the orientation treatment is performed by rubbing. The rubbing alignment treatment is a method of contacting the surface of the alignment film while rotating a drum wound with a short velvet-like cloth made of rayon, cotton, etc. The rubbing alignment film has its surface Fine grooves are formed in one direction, and liquid crystal molecules in contact with the fine grooves can be aligned in one direction.
The alignment film may be subjected to a photo-alignment treatment other than the method by the rubbing treatment. The photo-alignment treatment forms a photo-alignment film containing photoactive molecules such as azobenzene-based polymer and polyvinyl cinnamate on the surface of the base material, and linearly polarized light or oblique non-polarized light having a wavelength causing the photochemical reaction of the photoactive molecules. To generate anisotropy on the surface of the photo-alignment film. In the photo-alignment film subjected to the photo-alignment treatment, the alignment of the molecular long axis on the outermost surface of the film is generated by incident light, and the liquid crystal molecules contacting the outermost surface molecule can be aligned.
As the material for the photo-alignment film, in addition to the above azobenzene polymer, polyvinyl cinnamate, etc., photoisomerization, photodimerization, photocyclization by linearly polarized light or oblique non-polarized light having a wavelength causing photochemical reaction of the photoactive molecule, There is no particular limitation as long as it can generate anisotropy on the film surface by any reaction selected from photocrosslinking, photolysis, and photolysis-bonding, and it can be appropriately selected according to the purpose. For example, "Masaki Hasegawa, Journal of the Japanese Liquid Crystal Society, Vol. 3 No. 1, p3 (1999)", "Yasumasa Takeuchi, Journal of the Japanese Liquid Crystal Society, Vol. 3 No. 4, p 262 (1999)", etc. The photo-alignment film material currently used can be used.
When liquid crystal is applied to the alignment film, the liquid crystal molecules are aligned by using at least one of fine grooves on the alignment film surface and alignment of molecules on the outermost surface as a driving force.

-UV curable liquid crystal compounds-
The ultraviolet curable liquid crystal compound is not particularly limited as long as it has a polymerizable group and is cured by irradiation with ultraviolet rays, and can be appropriately selected according to the purpose. Thermotropic liquid crystal compound, lyotropic liquid crystal compound, etc. Is mentioned. Among these, a thermotropic liquid crystal compound is particularly preferable from the viewpoint of high orientation.

  Examples of the ultraviolet curable liquid crystal compound include compounds represented by the following structural formulas. However, it is not limited to these.

  As the ultraviolet curable liquid crystal compound, a commercially available product can be used. Examples of the commercially available product include a product name PALIOCOLOR LC242 manufactured by BASF; a product name E7 manufactured by Merck; and a product name manufactured by Wacker-Chem. LC-Slicon-CC3767; trade names L35, L42, L55, L59, L63, L79, and L83 manufactured by Takasago Inc.

  10-99 mass% is preferable with respect to the total solid mass of the said anisotropic absorption film coating liquid, and, as for content of the said ultraviolet curable liquid crystal compound, 20-95 mass% is more preferable.

-Photopolymerization initiator-
The anisotropic absorption film coating solution contains a photopolymerization initiator. There is no restriction | limiting in particular as said photoinitiator, According to the objective, it can select suitably according to the objective, For example, p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine, 2- (p-butoxystyryl) -5-trichloromethyl 1,3,4-oxadiazole, 9-phenylacridine, 9,10-dimethylbenzphenazine, benzyldimethyl ketal, benzophenone and Michler's ketone, hexaarylbiimidazole and mercapto Examples include benzimidazole, thioxanthone and amine. These may be used individually by 1 type and may use 2 or more types together.
As the photopolymerization initiator, commercially available products can be used. Examples of the commercially available products include trade names of Irgacure 907, Irgacure 369, Irgacure 784, and Irgacure 814 manufactured by Ciba Specialty Chemicals; And Lucylin TPO.
0.1-20 mass% is preferable with respect to the total solid content mass of the said anisotropic absorption film coating liquid, and, as for the addition amount of the said photoinitiator, 0.2-5 mass% is more preferable.

-Anisotropic absorbing material-
The anisotropic absorbing material is a material having an average aspect ratio (major axis length / minor axis length) of 1.5 or more and exhibiting anisotropic absorption, and anisotropic metal nanoparticles and carbon. It is preferably any one of nanotubes.

-Anisotropic metal nanoparticles-
The anisotropic metal nanoparticles are rod-shaped metal fine particles having a nano size of several nm to 100 nm. 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 to 50 nm, and more preferably 5 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 to 1,000 nm, and more preferably 10 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 to 50 nm, a major axis length of 10 to 1000 nm, and an aspect ratio of 1.5 or more change the absorption position between the minor axis direction and the major axis direction. Therefore, an anisotropic absorption film in which such anisotropic metal nanoparticles are oriented substantially horizontally with respect to the base glass surface (horizontal plane) becomes an anisotropic absorption layer.
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.

Examples of the metal species of the anisotropic metal nanoparticles include gold, silver, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, zinc, cobalt, nickel, chromium, titanium, tantalum, tungsten, Examples thereof include indium, aluminum, and alloys thereof. Among these, gold, silver, copper, and aluminum are preferable, and silver and gold are particularly preferable.
Next, gold nanorods as a suitable example of anisotropic metal nanoparticles will be described.

  There is no restriction | limiting in particular as a manufacturing method of the said gold nanorod, Although it can select suitably according to the objective, For example, (1) Electrolytic method, (2) Chemical reduction method, (3) Photoreduction method etc. are mentioned. It is done.

(1) Electrolytic method [Y. -Y. Yu, S .; -S. Chang, C.I. -L. Lee, C.I. R. C. Wang, J .; Phys. Chem. B, 101, 6661 (1997)] conducts constant current electrolysis of an aqueous solution containing a cationic surfactant, and leaches gold clusters from the metal plate of the anode to produce gold nanorods. As the surfactant, a quaternary ammonium salt having a structure in which four hydrophobic substituents are bonded to a nitrogen atom is used, and a compound that does not form an autonomous molecular assembly, for example, tetradodecyl ammonium bromide (TDAB) Etc. are added. When producing gold nanorods, the gold supply source is a gold cluster leached from the anode gold plate, and no gold salt such as chloroauric acid is used. During electrolysis, an ultrasonic wave is irradiated, and a silver plate is immersed in the solution to promote the growth of gold nanorods.
In this electrolytic method, the length of the gold nanorods generated can be controlled by changing the area of the silver plate immersed separately from the electrodes. By adjusting the length of the gold nanorod, the position of the absorption band in the near infrared light region can be set between about 700 nm and about 1200 nm. If the reaction conditions are kept constant, gold nanorods having a certain shape can be produced to some extent. However, the surfactant solution used for electrolysis is a complex system containing excess quaternary ammonium salt, cyclohexane and acetone, and has uncertain elements such as ultrasonic irradiation, so the shape of the gold nanorods to be produced and various preparation conditions It is difficult to optimize the gold nanorod preparation conditions by theoretically analyzing the causal relationship. In addition, due to the nature of electrolysis, it is essentially not easy to scale up and is not suitable for preparing a large amount of gold nanorods.

(2) Chemical reduction method [N. R. Jana, L .; Gearheart, C.I. J. et al. Murphy, J. et al. Phys. Chem. B, 105, 4065 (2001)] reduces chloroauric acid with NaBH4 to produce gold nanoparticles. These gold nanoparticles are used as “seed particles” and grown in solution to obtain gold nanorods. The length of the gold nanorods generated is determined by the ratio of the amount of the “seed particles” to the chloroauric acid added to the growth solution. In this chemical reduction method, gold nanorods longer than the electrolytic method (1) can be prepared, and gold nanorods having an absorption peak in the near-infrared light region exceeding 1,200 nm in length have been reported. .
However, this chemical reduction method requires two reaction vessels: preparation of “seed particles” and growth reaction. In addition, the generation of “seed particles” is completed in a few minutes, but it is difficult to increase the concentration of the gold nanorods to be generated, and the generation concentration of the gold nanorods is 1/10 or less of the electrolytic method of (1). is there.

  (3) Photoreduction method [F. Kim, J .; H. Song, P.M. Yang, J. et al. Am. Chem. Soc. , 124, 14316 (2002)] adds chloroauric acid to the same solution as the electrolytic method of (1), and reduces chloroauric acid by ultraviolet irradiation. A low-pressure mercury lamp is used for ultraviolet irradiation. In this photoreduction method, gold nanorods can be generated without generating seed particles. The length of the gold nanorod can be controlled by the irradiation time. It is characteristic that the shape of the generated gold nanorods is uniform. In the electrolysis method (1), since a large amount of spherical particles coexist after the reaction, fractionation by centrifugation is necessary, but in this photoreduction method, fractionation processing is unnecessary because the proportion of spherical particles is small. . In addition, reproducibility is good, and gold nanorods of the same size can be obtained almost certainly by a constant operation.

--Carbon nanotube--
The carbon nanotube is tubular carbon made of elongated carbon having a fiber diameter of 1 to 1,000 nm, a length of 0.1 to 1,000 μm, and an aspect ratio of 100 to 10,000.
Known methods for producing the carbon nanotube include an arc discharge method, a laser evaporation method, a thermal CVD method, a plasma CVD method, and the like. The carbon nanotubes obtained by the arc discharge method and the laser evaporation method include single-walled carbon nanotubes (SWNT: Single Wall Nanotube) having only one graphene sheet and multi-walled carbon nanotubes (MWNT: Multi Wall Nanotube) comprising a plurality of graphene sheets. ) And exist.
In addition, MWNTs can be mainly produced by the thermal CVD method and the plasma CVD method. The SWNT has a structure in which one graphite sheet in which carbon atoms are connected in a hexagonal shape by the strongest bond called SP2 bond is wound in a cylindrical shape.

  The carbon nanotubes (SWNT, MWNT) are tubular materials having a diameter of 0.4 nm to 10 nm and a length of 0.1 μm to several hundreds of μm, each having a structure in which one graphite sheet is rolled into a cylindrical shape. Depending on the direction in which the graphite sheet is rolled, it has a unique property of becoming a metal or a semiconductor. Such a carbon nanotube has a property that light absorption and light emission easily occur in the length direction and light absorption and light emission hardly occur in the radial direction, and is used as an anisotropic absorption material.

  The content of the anisotropic absorbent material is preferably 0.1 to 50.0% by mass, more preferably 1.0 to 30.0% by mass with respect to the total solid mass of the anisotropic absorbent film coating solution. . When the content is less than 0.1% by mass, sufficient polarization may not be obtained. When the content exceeds 50% by mass, film formation cannot be performed well or the transmittance of the anisotropic absorption film is low. May fall too much.

-Polymer surfactant-
The anisotropic absorption film coating liquid preferably contains a polymer surfactant. By adjusting the addition amount of the polymer surfactant, the inclination angle of the long axis of the anisotropic absorbent material with respect to the base material surface can be adjusted appropriately from 0 degree to 70 degrees.
As described above, in order to align the major axis of the anisotropic absorbing material at 0 ° to 70 ° with respect to the substrate surface, the liquid crystal layer as a medium must be aligned at 0 ° to 70 °. The liquid crystal layer formed on the alignment film on one side of the substrate may become so-called “spray alignment” that rises from the alignment film side toward the air interface side by adjusting the end to be hydrophobic, but as it is, The rise of the anisotropic absorbent material at the air interface is insufficient, and the force for orienting the anisotropic absorbent material is weak. Therefore, if a polymer surfactant that has a strong interaction with the liquid crystal layer to be used is selected and added to the liquid crystal layer, the polymer surfactant floats to the air interface side during alignment ripening, and the adjacent liquid crystal is strongly vertically aligned. . As a result, the alignment state of the entire liquid crystal layer is a horizontal alignment with a slight pretilt angle on the alignment film side, and rises toward the air interface side in the thickness direction and becomes a vertical alignment, so-called “spray alignment state” (That is, oblique orientation).

As such a polymeric surfactant, a nonionic type is preferable, and those having a strong interaction with the liquid crystal compound to be used can be selected from commercially available polymeric surfactants. Examples include trade name “MegaFuck F780F” and trade name “B1176” manufactured by Kogyo Corporation.
0-15 mass% is preferable with respect to the total solid content mass of the said anisotropic absorption film coating liquid, and, as for content of the said polymeric surfactant, 0-5 mass% is more preferable.

The anisotropic absorption film coating liquid is, for example, an ultraviolet curable liquid crystal compound, an anisotropic absorption material having an average aspect ratio of 1.5 or more, a photopolymerization initiator, preferably a polymer surfactant, Accordingly, it can be prepared by dissolving or dispersing other components in a solvent.
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, for example, chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene Halogenated hydrocarbons such as phenol; phenols such as phenol, p-chlorophenol, o-chlorophenol, m-cresol, o-cresol, p-cresol; benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxy Aromatic hydrocarbons such as benzene; ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; Ester solvents such as ethyl acetate and butyl acetate; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol Alcohol solvents such as dimethylformamide, dimethylacetamide, etc .; Nitriles such as acetonitrile and butyronitrile; Ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran, dioxane; Carbon disulfide, ethyl cellosolve, butyl Examples include cell solves. These may be used individually by 1 type and may use 2 or more types together.

The said anisotropic absorption film coating liquid is apply | coated on the base material which has an oriented film on the surface, It is made to dry and a coating layer is formed.
Examples of the coating method include spin coating, casting, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing.

<Curing process>
In the curing step, the coating layer obtained in the coating layer forming step is cured by irradiating with ultraviolet rays in a state where the coating layer is heated to a temperature at which a liquid crystal phase is expressed, and the major axis of the anisotropic absorbing material is set to the base material surface. Is a step of inclining at an angle of 0 degrees or more and 70 degrees or less.

After forming the coating layer, in order to fix the orientation state of the anisotropic absorption material, the coating layer is irradiated with ultraviolet rays while being heated to a temperature at which the liquid crystal phase is developed. Thereby, the anisotropic absorption film in which the major axis of the anisotropic absorption material is inclined at an angle of 0 degree or more and 70 degrees or less with respect to the base material surface (horizontal plane) can be formed.
The heating condition is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 50 to 120 ° C.
There is no restriction | limiting in particular as conditions for the said ultraviolet irradiation, According to the objective, it can select suitably, For example, 160-380 nm is preferable and, as for irradiation ultraviolet rays, 250-380 nm is more preferable. For example, the irradiation time is preferably 0.1 to 600 seconds, and more preferably 0.3 to 300 seconds.
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).

The anisotropic absorption film of the present invention obtained as described above is excellent in anisotropic absorption because the major axis of the anisotropic absorption material is inclined at an angle of 0 ° to 70 ° with respect to the substrate surface (horizontal plane). Have sex.
The major axis of the anisotropic absorbing material preferably has an orientation angle within 0 ± 15 degrees with respect to the orientation direction.
Here, as shown in FIG. 2, the tilt angle means an angle θ formed by the substrate (horizontal plane) 1 and the long axis of the anisotropic nanoparticle. In sample A, the tilt angle θ is 0 degree (substrate In Sample B, the inclination angle θ is 55 degrees.
As shown in FIG. 3, the alignment angle means a deviation angle φ with respect to the alignment direction of the liquid crystal molecules. In sample A, the alignment angle φ is 0 ± 0 degrees, and in sample B, the alignment angle φ is 0 ± 10. Degree.

-Anisotropic absorption film and its use-
FIG. 4 is a schematic cross-sectional view showing an example of the anisotropic absorption film of the present invention. In FIG. 4 a, the long axis of the anisotropic absorber P is arranged horizontally (0 degree) with respect to the substrate surface (horizontal plane) S. In FIG. 4 b and FIG. 4 c, the long axis of the anisotropic absorber P is arranged substantially horizontally (± 10 degrees) with respect to the substrate surface (horizontal plane) S.
FIG. 5 is a schematic cross-sectional view showing an example of the anisotropic absorption film of the present invention. In FIG. 5 a, the major axis of the anisotropic absorber P is inclined with respect to the base material surface (horizontal plane) S in an oblique direction (about 30 degrees). In FIG. 5 b, the long axis of the anisotropic absorber P is inclined in an oblique direction (about 45 degrees) with respect to the substrate surface (horizontal plane) S. In FIG. 5 c, the long axis of the anisotropic absorber P is inclined with respect to the base material surface (horizontal plane) S in an oblique direction (about 70 degrees).

  The anisotropic absorption film of the present invention can produce an absorption type polarizer by orienting an anisotropic absorption material having anisotropy in absorption characteristics. Because there is no stray light due to reflection, the structure of the optical device can be simplified. For example, it can be applied to projectors, liquid crystal monitors, liquid crystal televisions, etc. Glasses for various vehicles: Can be widely used in various fields such as general detached houses, apartment houses, office screws, stores, public facilities, building openings such as factory facilities, 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)
<Preparation of anisotropic absorption film with gold nanorods aligned by guest-host type liquid crystal method>
-Production of alignment film-
Polyvinyl alcohol (PVA) alignment film solution (methanol solution) is spin-coated at 1,000 rpm for 30 seconds on a clean white glass plate with a 10 cm square and a thickness of 1.1 mm, and dried at 100 ° C. for 3 minutes. A 1.0 μm PVA membrane was prepared. This PVA film surface was rubbed twice with a rubbing apparatus (manufactured by Joyo Engineering Co., Ltd., rotation speed: 1,000 rpm, pushing amount: 0.35 mm) to produce a PVA alignment film. This glass plate with a PVA alignment film was cut into 30 mm × 28 mm squares to form a substrate.

-Preparation of coating solution for anisotropic absorption film-
A liquid crystal compound having a photopolymerizable group (BASF, trade name: PALIOCOLOR LC242) 3.04 g dissolved in methyl ethyl ketone (MEK) 5.07 g, an initiator solution [Irgacure 907 (Ciba Specialty Chemicals) 0.90 g and Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 0.30 g dissolved in 8.80 g of methyl ethyl ketone (MEK)] 1.11 g was added, and the mixture was completely dissolved by stirring for 5 minutes. .
Next, a 5.0 mass% toluene solution of gold nanorods (trade name: Au-4, manufactured by Mitsubishi Materials Corporation, major axis length 45 nm, minor axis length 13 nm, average aspect ratio 3. 4) An anisotropic absorption film coating solution was prepared by adding 2.5 g and stirring for 5 minutes.

-Orientation and curing of gold nanorods-
The obtained anisotropic absorption film coating solution was spin-coated on the PVA alignment film under the conditions of a rotation speed of 500 rpm for 15 seconds, and placed on a hot plate so that the surface opposite to the coating surface was in contact with After heating at ° C for 1 minute, irradiation with ultraviolet rays (UV) (high pressure mercury lamp, 1 kW, 330 mJ / mm ² ) in the heated state formed an anisotropic absorption film having a thickness of 2.5 μm with gold nanorods oriented. .

<Orientation of gold nanorods>
When the slice of the obtained anisotropic absorption film was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), 78% by number or more of 500 gold nanorods were ± with respect to the orientation direction. It was oriented within 10 degrees, and the tilt angle with respect to the substrate surface (horizontal plane) was arranged at 0 to 5 degrees.

-Optical property evaluation-
About the glass plate which has the obtained anisotropic absorption film, various characteristics were evaluated as follows. The results are shown in Table 1.

<Degree of polarization>
Using an ultraviolet / visible spectrophotometer (manufactured by JASCO Corporation, V-560), the polarization transmission spectrum of the anisotropic absorption film was measured. The degree of polarization is transmitted with a visible to near-infrared polarizer attached as a window plate, with the orientation axis of the produced anisotropic absorption film parallel and perpendicular to the absorption axis of the window plate polarizer. The spectrum was measured and calculated based on the following polarization degree calculation formula. Further, when measuring the transmittance of the anisotropic absorption film, it was set and measured so that the orientation axis of the produced anisotropic absorption film was 45 ° with respect to the horizontal plane.
<< polarization degree calculation formula >>
P (%) = 100 * [(T || -T⊥) / (T || + T⊥)] ^1/2

<Light resistance>
Using a super high pressure mercury lamp, a brilliant test was conducted, the polarization degree and transmittance after 1,000 hours of turbulence were measured, and light resistance was evaluated by comparison with the initial stage.

(Example 2)
In Example 1, gold nanorods were prepared in the same manner as in Example 1, except that 0.1 g of a polymer surfactant (B1176, manufactured by Dainippon Ink & Chemicals, Inc.) was added to the anisotropic absorption film coating solution. An anisotropic absorption film having a thickness of 2.5 μm was prepared.

<Orientation of gold nanorods>
When the slice of the obtained anisotropic absorption film was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), 75% or more of 500 gold nanorods were ± The orientation was within 10 degrees, and the inclination angle with respect to the substrate glass surface (horizontal plane) was arranged at 55 ± 5 degrees.

  Various characteristics of the obtained glass plate having the anisotropic absorption film were measured in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
<Preparation of anisotropic absorption film with aligned carbon nanotubes by guest-host type liquid crystal method>
In Example 1, an anisotropic absorption film coating solution containing the following carbon nanotubes was used, and the carbon nanotubes were oriented in the same manner as in Example 1 except that the carbon nanotubes were oriented and cured. An absorption film was prepared.
-Preparation of coating solution for anisotropic absorption film-
A liquid crystal compound having a photopolymerizable group (BASF, trade name: PALIOCOLOR LC242) 3.04 g dissolved in methyl ethyl ketone (MEK) 5.07 g, an initiator solution [Irgacure 907 (Ciba Specialty Chemicals) 0.90 g and Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) 0.30 g dissolved in 8.80 g of methyl ethyl ketone (MEK)] 1.11 g was added, and the mixture was completely dissolved by stirring for 5 minutes. .
Next, 1.0 g of carbon nanotubes (manufactured by Aldrich, major axis length of 300 to 500 nm, minor axis length of 5 to 10 nm, average aspect ratio of 30 to 100) is added to the obtained solution and stirred for 30 minutes. Then, an anisotropic absorption film coating solution was prepared by dispersing the carbon tube.

-Orientation and curing of carbon nanotubes-
The obtained anisotropic absorption film coating solution is bar coated on the PVA alignment film, placed on a hot plate so that the opposite surface of the coated surface is in contact, heated at 90 ° C. for 1 minute, and then heated. By irradiation with ultraviolet rays (UV) (high pressure mercury lamp, 1 kW, 330 mJ / mm ² ), an anisotropic absorption film having a thickness of 3.4 μm with aligned carbon nanotubes was produced.

<Orientation of carbon nanotubes>
When the slice of the obtained anisotropic absorption film was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), 75% or more of 500 carbon nanotubes were ± It was oriented within 10 degrees, and the tilt angle with respect to the substrate surface (horizontal plane) was arranged at 0 to 5 degrees.

  Next, various properties of the obtained glass plate having the anisotropic absorption film were measured in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In Example 3, carbon nanotubes were prepared in the same manner as in Example 3 except that 0.1 g of a polymer surfactant (B1176, manufactured by Dainippon Ink & Chemicals, Inc.) was added to the anisotropic absorbent film coating solution. An anisotropic absorption film having a thickness of 3.4 .mu.m was prepared.

<Orientation of carbon nanotubes>
When the slice of the obtained anisotropic absorption film was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), 73% by number or more of 500 carbon nanotubes were ± The orientation was within 10 degrees, and the inclination angle with respect to the substrate glass surface (horizontal plane) was arranged at 55 ± 5 degrees.

  Various characteristics of the obtained glass plate having the anisotropic absorption film were measured in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
In Example 1, the anisotropic absorption film of Example 5 was produced in the same manner as in Example 1 except that the anisotropic absorption film coating solution was changed as follows.
-Preparation of coating solution for anisotropic absorption film-
In a liquid crystal solution obtained by dissolving 4.0 g of a lyotropic liquid crystal compound (LLC-1) represented by the following structural formula in 6.0 g of pure water, an aqueous solution of 1.0% by mass of gold nanorods (major axis length 45.5 nm, 0.1 g of minor axis length 12.5 nm, average aspect ratio 3.5) is added, and further 2.0% by mass of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) is added and stirred for 5 minutes. Thus, an anisotropic absorption film coating solution was prepared.
<Orientation of gold nanorods>
When the slice of the obtained anisotropic absorption film was observed with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-2010), 70% by number or more of 500 gold nanorods were ± with respect to the orientation direction. It was oriented within 10 degrees, and the tilt angle with respect to the substrate surface (horizontal plane) was arranged at 0 to 5 degrees.

  Next, various characteristics of the obtained glass plate having the anisotropic absorption film were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, a film of Comparative Example 1 was produced in the same manner as Example 1 except that an anisotropic absorption film in which gold nanorods were oriented was not provided.
Various characteristics of the obtained glass plate having the film of Comparative Example 1 were evaluated in the same manner as in Example 1. The results are shown in Table 1.

In Table 1, all measured values at λ = 800 nm are shown. For Examples 2 and 4, the measurement was performed in a state where the sample was tilted by 55 ° with respect to the light source. Moreover, about Example 1, 3, 5 and the comparative example 1, it measured in the state which set the sample perpendicular | vertical with respect to the light source.

  The anisotropic absorption film manufactured by the method for manufacturing an anisotropic absorption film of the present invention can orient the anisotropic absorption material at a certain angle without lowering the density in the same plane, and is light resistant. For example, it can be applied to projectors, liquid crystal monitors, liquid crystal televisions, and the like.

FIG. 1 is a diagram showing an absorption spectrum of a gold nanorod. FIG. 2 is a schematic cross-sectional view for explaining the definition of the tilt angle of anisotropic nanoparticles. FIG. 3 is a schematic view for explaining the definition of the orientation angle of anisotropic nanoparticles. FIG. 4 is a diagram showing an example of the anisotropic absorption film of the present invention. FIG. 5 is a diagram showing another example of the anisotropic absorption film of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Anisotropic absorption film P Anisotropic absorption material S Horizontal surface

Claims (5)

An anisotropic absorption film coating solution containing at least an ultraviolet curable liquid crystal compound, a photopolymerization initiator, and an anisotropic absorption material having an average aspect ratio of 1.5 or more on a substrate having an alignment film on the surface Coating layer forming step of coating and drying to form a coating layer;
The coating layer is heated to a temperature at which a liquid crystal phase is expressed and cured by irradiating with ultraviolet rays, so that the inclination angle of the long axis of the anisotropic absorbent material with respect to the substrate surface is aligned between 0 degree and 70 degrees. A method for producing an anisotropic absorption film, comprising: a curing step.   The method for producing an anisotropic absorption film according to claim 1, wherein the ultraviolet curable liquid crystal compound is a thermotropic liquid crystal compound.   The method for producing an anisotropic absorbing film according to claim 1, wherein the anisotropic absorbing film coating solution contains a polymer surfactant.   The method for producing an anisotropic absorption film according to any one of claims 1 to 3, wherein the anisotropic absorption material contains any one of anisotropic metal nanoparticles and carbon nanotubes. The manufacturing method of the anisotropic absorption film of Claim 4 in which an anisotropic metal nanoparticle contains at least 1 sort (s) selected from gold | metal | money, silver, copper, and aluminum.