JP2007148046A - Method of manufacturing grid polarizing film, grid polarizing film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a grid polarizing film which is excellent in polarizing separating performance and has a high light transmittance, with efficient, inexpensive and simple processes. <P>SOLUTION: The method of manufacturing the grid polarizing film comprises processes of: applying a solution prepared by dissolving resin into an organic solvent on a base material; vaporizing the organic solvent and, at the same time, condensing water vapor to prepare fine water droplets; vaporizing the fine water droplets to obtain a porous structure film; stretching the porous structure film in one direction; making the porous structure film finer by dry etching; forming a layer made of the material Z of which absolute value of difference between real part n and imaginary part κ of complex refractive index (N=n-iκ) is 1.0 or more on the porous structure film made finer; and forming a transparent protective film on the layer made of the material Z to obtain the grid polarizing film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a grid polarizing film used in optical communications, optical recording, sensors, image display devices, and the like, and in particular, it is excellent in polarization separation performance and high light transmission through an efficient and simple process. The present invention relates to a method of manufacturing a grid polarizing film having a rate.

  A grid polarizer is known as a kind of reflective polarizer. This is an optical component having a grid structure in which a large number of linear metals are arranged in parallel at a constant period. When the period of the grid structure is shorter than the wavelength of the incident light, this grid polarizer reflects a polarization component parallel to the metal line of the grid structure and transmits a perpendicular polarization component. Functions as a polarizer to be created. It has been proposed that this grid polarizer is used as an optical component of an isolator in optical communication, and as an optical component for increasing light utilization and improving luminance in a liquid crystal display device.

Various methods for producing a grid polarizing film in which a grid structure is formed on a resin film substrate have been proposed.
For example, in Patent Document 1, a metal film is formed on a transparent and flexible substrate, and the substrate and the metal film are stretched below the melting point of the metal film, thereby cracking the metal film in a direction perpendicular to the stretching direction. A method of manufacturing a grid-type polarizing optical element that is generated and forms a structure composed of a metal part having a anisotropic shape and a dielectric part is disclosed.

Patent Document 2 discloses a film having a higher-order structure in which crystal parts and amorphous parts are alternately connected, or a film having a higher-order structure in which two kinds of phases having different glass transition temperatures are alternately connected in the stretching direction. A polarizing optical element that forms a structure composed of an anisotropic conductive portion and a polymer dielectric portion by forming a conductive thin film on the entire surface to obtain a composite film, stretching the composite film, and heat-fixing the composite film. A manufacturing method is disclosed.
In Patent Document 3, a light-transmitting hydrophilic resin thin film layer is formed on a light-transmitting substrate, and a thin metal wire is formed on the thin film layer with a desired fine periodic structure. A wire grid polarizer in which a layer made of a hydrophobic resin having optical transparency is formed is disclosed.

  However, the polarizing optical element obtained by the manufacturing method disclosed in Patent Document 1 has no regularity in cracking of the metal thin film, and the metal thin film may be peeled off from the substrate at the time of manufacturing. It is difficult to demonstrate. In addition, the polarizing optical element obtained by the manufacturing method disclosed in Patent Document 2 has low light transmittance, and it has been difficult to sufficiently meet the demand for high luminance such as a liquid crystal display device. Furthermore, although the polarizing optical element obtained by the manufacturing method disclosed in Patent Document 3 can obtain an element having excellent polarization characteristics, it has been difficult to sufficiently meet market demands because of low productivity.

On the other hand, an optical functional film using a honeycomb structure has been proposed. For example, Patent Document 4 discloses that a solution in which a hydrophobic polymer and an amphiphilic polymer are dissolved in a hydrophobic organic solvent at a mass ratio of 50:50 to 99: 1 is developed on a substrate, and the relative humidity is formed on the substrate. By sending 50 to 95% of gas at a constant flow rate, the organic solvent is evaporated, and at the same time, water vapor is condensed on the surface of the solution. And a method for manufacturing an optical functional film using the honeycomb structure is disclosed. The honeycomb structure obtained by the method of Patent Document 4 is one in which pores having a pore diameter of 110 nm or 1 μm are regularly arranged in a hexagonal shape. Patent Document 4 discloses that this optical functional film can be applied as an antireflection film for electronic displays, and as a surface decoration film for decorations, signs, and the like.
However, the technique disclosed in Patent Document 4 is a technique related to an optical functional film using the structural regularity of a honeycomb structure, and a polarizing optical element cannot be obtained only by using the obtained honeycomb structure.

JP 2001-74935 A JP 2005-148416 A JP-A-2005-70456 JP 2003-294905 A

  An object of the present invention is to provide a method for producing a grid polarizing film having an excellent polarization separation performance and a high light transmittance through an efficient and simple process.

  Therefore, as a result of investigations to achieve the above-mentioned object, the present inventors formed a porous structure film such as a honeycomb structure on a base material, and stretched it in one direction to make the porous structure film anisotropic. Thus, it has been found that a grid polarizing film having high light transmittance and excellent polarization separation performance can be obtained efficiently and simply, and the present invention has been completed based on this finding.

Thus, according to the present invention,
(1) A solution in which a resin is dissolved in an organic solvent is applied on a substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
Then stretch in one direction,
A grid including forming a layer made of material Z having an absolute value of a difference between a real part n and an imaginary part κ of a complex refractive index (N = n−iκ) of 1.0 or more on a stretched porous structure film A method for producing a polarizing film.

(2) A solution in which a resin is dissolved in an organic solvent is applied on a substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
On the porous structure film, a layer made of the material Z having an absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) of 1.0 or more is formed.
Then, the manufacturing method of a grid polarizing film including extending | stretching to one direction.
(3) The manufacturing method of the grid polarizing film as described in said (1) or (2) including forming a transparent protective film further.

(4) A solution in which a resin is dissolved in an organic solvent is applied on a substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
On the porous structure film, a layer made of the material Z having an absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) of 1.0 or more is formed.
A transparent protective film is formed on the layer made of the material Z,
Then, the manufacturing method of a grid polarizing film including extending | stretching to one direction.
(5) The method for producing a grid polarizing film according to any one of (1) to (4), wherein the solution is applied in an environment with a relative humidity of 70% or more.

(6) Furthermore, the manufacturing method of the grid polarizing film in any one of said (1)-(5) including carrying out the dry etching process of the surface of a porous structure film.
(7) The manufacturing method of the grid polarizing film in any one of said (1)-(6) whose material Z is a metal.
(8) The manufacturing method of the grid polarizing film in any one of said (1)-(7) whose base material is a long thing.
(9) The manufacturing method of the grid polarizing film as described in said (8) whose extending | stretching direction is substantially parallel to the vertical direction of a elongate base material.
Is provided.

Moreover, according to the present invention,
(10) A grid polarizing film obtained by the production method according to any one of (1) to (9).
(11) A grid polarizing film obtained by the production method according to (8) or (9) and having a polarization transmission axis substantially parallel to the width direction of the elongated substrate.
Is provided.

Furthermore, according to the present invention,
(12) A liquid crystal display device comprising the grid polarizing film according to (10) or (11).
Is provided.

  The method for producing a grid polarizing film of the present invention is a combination of a method for producing a porous structure film obtained by utilizing a self-organization phenomenon, a stretching method, and a method for producing a metal film or the like under predetermined conditions. It can be performed efficiently and simply. The grid polarizing film obtained by the production method of the present invention has high light transmittance, separates natural light into two types of linearly polarized light, reflects one linearly polarized light, and transmits the other linearly polarized light. be able to. Furthermore, since it has sufficient flexibility and strength, it is easy to handle when attaching the grid polarizing film to a liquid crystal display device or the like. Further, when the grid polarizing film of the present invention is disposed between the liquid crystal cell of the liquid crystal display device and the backlight device, the light emitted from the backlight can be used effectively and the brightness of the display screen can be improved.

  In the method for producing a grid polarizing film of the present invention, a solution in which a resin is dissolved in an organic solvent is applied onto a substrate, and the organic solvent is evaporated, and at the same time, water vapor is condensed to generate minute water droplets. The porous structure film is obtained by evaporating, and then stretched in one direction. On the stretched porous structure film, the absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) is This includes forming a layer made of material Z of 1.0 or more.

  The base material used for the manufacturing method of the grid polarizing film of this invention will not be specifically limited if it is transparent and can be extended | stretched. For example, transparent resin is mentioned. From the viewpoint of processability, the transparent resin preferably has a glass transition temperature of 60 to 200 ° C, more preferably 100 to 180 ° C. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

  Transparent resins include polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, cellulose diacetate, cellulose triacetate, alicyclic ring And olefin polymers. Of these, alicyclic olefin polymers are preferred from the viewpoints of transparency, low hygroscopicity, dimensional stability, and processability. Examples of the alicyclic olefin polymer include cyclic olefin random multicomponent copolymers described in JP-A No. 05-310845, US Pat. No. 5,179,171, JP-A No. 05-97978, and US Pat. No. 5,202,388. Examples thereof include the hydrogenated polymers described, the thermoplastic dicyclopentadiene-based ring-opening polymers described in JP-A No. 11-124429, and International Publication No. 99/20676, and hydrogenated products thereof.

The transparent resin used in the present invention contains coloring agents such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents, etc. An agent may be appropriately blended.
A base material is obtained by shape | molding the said transparent resin by a well-known method. Examples of the molding method include a cast molding method, an extrusion molding method, and an inflation molding method.

The substrate is usually in the form of a sheet or film, and preferably has a smooth surface with a light transmittance in the visible region of 400 to 700 nm of 80% or more. The substrate has an average thickness of usually 5 μm to 1 mm, preferably 20 to 200 μm, from the viewpoint of handleability.
The substrate is a value defined by the retardation Re (Re = d × measured at that wavelength _{550nm (n x -n y),} n x, plane principal refractive index of _{n y} the substrate; d is The average thickness of the base material) is not particularly limited. The difference in the retardation Re (retardation unevenness) at any two points in the plane of the substrate is preferably 10 nm or less, more preferably 5 nm or less. When the retardation unevenness is large, the brightness of the display surface tends to vary when used in a liquid crystal display device.

The resin solution used for the manufacturing method of the grid polarizing film of this invention melt | dissolves resin in the organic solvent.
Resins used for the resin solution are hydrophobic polymers such as polyethylene, polypropylene, polystyrene, polyacrylate, polymethacrylate, polyacrylamide, polymethacrylamide, polyvinyl chloride, polyvinylidene chloride, polyvinyl ether, polyvinyl carbazole, polyvinyl acetate, polyvinyl Vinyl polymerized polymers such as alcohol; Polyesters such as polyethylene terephthalate, polycarbonate and polyethylene naphthalate; Polylactones, polyamides or polyimides (eg nylon and polyamic acid); Polyaromatics; Polyethers such as polyethersulfone; Polysiloxane derivatives, fats And cyclic olefin polymers. Of these, alicyclic olefin polymers are preferred from the viewpoints of transparency, low hygroscopicity, dimensional stability, and processability. Examples of the alicyclic olefin polymer include cyclic olefin random multicomponent copolymers described in JP-A No. 05-310845, US Pat. No. 5,179,171, JP-A No. 05-97978, and US Pat. No. 5,202,388. Examples thereof include the hydrogenated polymers described, the thermoplastic dicyclopentadiene-based ring-opening polymers described in JP-A No. 11-124429, and International Publication No. 99/20676, and hydrogenated products thereof. Amphiphilic polymer such as polyacrylamide as main chain skeleton, dodecyl group as hydrophobic side chain and carboxyl group as hydrophilic side chain as amphiphilic polymer, and polyethylene glycol / polypropylene glycol block copolymer Etc. Further, polymers having hydrophilic groups such as epoxy groups, carboxyl groups, carbonyloxycarboxyl groups, amino groups, amide groups, etc. as amphiphilic polymers having the alicyclic olefin polymer as a main chain skeleton and hydrophilic side chains. Can be used. Such an amphiphilic polymer having an alicyclic olefin polymer as a main skeleton can be produced by a technique described in International Publication No. 01/83576. Further, modification may be performed using a hydrophilic hydrophilic side chain. These resins can be used alone or in combination of two or more.

  When the resin is used in combination in the present invention, it is preferable to combine a hydrophobic polymer and an amphiphilic polymer. In that case, the ratio of the hydrophobic polymer to the amphiphilic polymer is preferably 99: 1 to 50:50 (mass ratio). When the amphiphilic polymer ratio is less than 1% by mass, there is a tendency that a uniform honeycomb structure cannot be obtained, and when the ratio exceeds 50% by mass, sufficient film stability, particularly mechanical stability, is obtained. There is a tendency to become unusable.

  The number average molecular weight (Mn) of the resin used in the present invention is usually 1,000 to 10,000,000, preferably 5,000 to 1,000,000.

The organic solvent used for the resin solution is preferably water-insoluble. For example, halogen-based organic solvents such as chloroform and methylene chloride; hydrocarbons such as hexane, cyclohexane, benzene, toluene, and xylene; esters such as ethyl acetate and butyl acetate; water-insoluble ketones such as methyl isobutyl ketone; diethyl ether And ethers such as carbon disulfide.
These organic solvents may be used alone or as a mixed solvent in which these solvents are combined.

  The resin concentration of the resin solution is usually 0.01% by mass to 10% by mass, preferably 0.05% by mass to 5% by mass. When the resin concentration is lower than 0.01% by mass, the resulting film tends to have insufficient mechanical strength, and the size and arrangement of pores tend to be disturbed. Further, when the polymer concentration is 10% by mass or more, there is a tendency that a sufficient porous structure film cannot be obtained.

  The method for applying the resin solution to the substrate is not particularly limited. For example, spin coating method, roll coating method, flow coating method, printing method, dip coating method, casting film forming method, bar coating method, die coating method, gravure method Examples include printing methods. In the present invention, it is preferable to apply the resin solution in an environment having a relative humidity of 70% or more in order to easily obtain regularly arranged pores.

  Next, the organic solvent is evaporated, and at the same time, the water vapor is condensed to generate fine water droplets. The method for causing the evaporation of the organic solvent and the condensation of the water vapor at the same time is not particularly limited, and examples thereof include a method of sending a gas having a high relative humidity to the coating layer at a constant flow rate. Specifically, air or an inert gas such as nitrogen gas / argon gas is conditioned to a relative humidity of 70 to 95%, subjected to dust removal treatment such as passing through a filter, and blown to the coating layer. If the relative humidity is less than 70%, water condensation on the surface of the coating layer tends to be insufficient. If it exceeds 95%, it is difficult to control the environment, and it tends to be difficult to maintain a uniform film formation. The blowing speed is preferably constant in the range of 0.05 m / s to 1 m / s. If it is less than 0.05 m / s, it tends to be difficult to control the environment. Moreover, the wind speed exceeding 1 m / s causes disturbance of the coating layer surface and tends to make it difficult to obtain a uniform film.

  The fine water droplets are then evaporated. The evaporation of minute water droplets can be performed, for example, by placing the coating layer in an environment with a low relative humidity. Due to the generation and evaporation of the minute water droplets, pores are generated in the coating layer. The pores are regularly arranged in a honeycomb shape to form a porous structure as shown in FIG.

  The pores formed in this porous structure film usually have a pore diameter of 50 nm to 100 μm, preferably 100 nm to 50 μm, more preferably 200 nm to 20 μm, and most preferably 500 nm to 10 μm. When the pore diameter is less than 50 nm, the pores are not arranged in a honeycomb shape, and each pore diameter tends to vary. On the other hand, when the pore diameter exceeds 100 μm, the shape of the pores collapses from a perfect circle, and there is a tendency that an isotropic film cannot be obtained.

  In order to reduce the pore size of the pores formed in the porous structure film, for example, a low boiling point solvent is used as the organic solvent used, the substrate temperature is increased, or the coating speed is increased to increase the coating layer. What is necessary is just to reduce the thickness of.

  The thickness of the porous structure film can be usually adjusted from the same thickness as the pore diameter to 200 μm. By increasing the concentration of the resin solution to be applied, it is possible to provide holes that do not penetrate to the substrate side surface. In this case, the layer thickness from the base material to the bottom of the pore is not particularly limited, and is usually 500 μm or less.

  The porous structure film used in the present invention may contain other compounding agents. The compounding agent is not particularly limited, and inorganic fine particles; stabilizers such as antioxidants, heat stabilizers, light stabilizers, weathering stabilizers, ultraviolet absorbers, near infrared absorbers; resin modifiers such as lubricants and plasticizers. Quality agents; coloring agents such as dyes and pigments; antistatic agents and the like. Among these compounding agents, inorganic fine particles are preferable from the viewpoint that the pores of the porous structure film can be stably formed. These compounding agents can be used alone or in combination of two or more. Moreover, the compounding quantity is suitably selected in the range which does not impair the objective of this invention. Although the addition amount of these compounding agents is not particularly limited, it is usually 0.001 to 50 parts by weight, preferably 0.005 to 20 parts by weight with respect to 100 parts by weight of the resin forming the porous structure film.

  As the inorganic fine particles, those having a maximum particle diameter of 100 nm or less are preferably used, and those having a maximum particle diameter of 50 nm or less are more preferable. By using the inorganic fine particles within the above range, the transparency and mechanical strength of the resulting porous structure film can be improved. Examples of the inorganic fine particles include inorganic fine particles made of a simple metal, or inorganic fine particles made of a metal oxide or sulfide. However, from the viewpoint of production, the fine particles may be inorganic fine particles made of a metal oxide or sulfide. preferable.

  These inorganic fine particles may contain a dispersant in order to improve dispersibility. Although it does not specifically limit as a dispersing agent, A fatty acid, surfactant, and a coupling agent are mentioned. Examples of fatty acids include saturated fatty acids having 4 to 30 carbon atoms such as stearic acid, and unsaturated fatty acids having 4 to 30 carbon atoms such as oleic acid, linoleic acid, and linolenic acid. Examples of surfactants include anionic surfactants such as sodium stearate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate; cationic surfactants such as N-laurylethanolamine, cetyltrimethylammonium chloride; Nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene stearate, sorbitan stearate, polyoxyethylene sorbitan stearate; amphoteric such as alkylaminocarboxylic acid, hydroxyethyl imidazoline sulfate, imidazoline sulfonic acid, etc. Surfactant; Fluorine-based surfactant; Silicone-based surfactant; (Meth) acrylic acid-based surfactant; Examples of coupling agents include silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, hexamethyldisilazane; triisostearoyl isopropyl titanate, di- (Dioctyl phosphate) titanate coupling agents such as diisopropyl titanate; aluminate coupling agents such as monoisopropoxyaluminum monomethacrylate monooleyl acetoacetate and diisopropoxyaluminum monooleyl acetoacetate;

  The obtained porous structure film is stretched in one direction. The stretching method is not particularly limited as long as it can be stretched in one direction. Examples thereof include a longitudinal uniaxial stretching method and a transverse uniaxial stretching method, and the longitudinal uniaxial stretching method is preferable. The draw ratio is preferably 1.25 to 10 times. Thus, by extending | stretching to one direction, a void | hole extends to one direction and it becomes an anisotropic porous structure film | membrane as shown in FIG. In the production method of the present invention, it is efficient to apply continuously using a long base material and continuously longitudinally stretch (stretch in a direction substantially parallel to the longitudinal direction of the long base material). It is preferable. The temperature during the stretching treatment is preferably between (Tg−30 ° C.) and (Tg + 60 ° C.), more preferably (Tg−), where Tg is the glass transition temperature of the resin forming the porous structure film. 10 ° C.) to (Tg + 50 ° C.).

The stretched porous structure film (anisotropic porous structure film) has elongated pores extending linearly. From the viewpoint of polarization characteristics of the obtained grid polarizing film, the pitch between holes in the direction orthogonal to the stretching direction is preferably ½ or less of the wavelength of light. The inter-hole pitch is usually 50 to 1000 nm. The width of the layer partitioning the pores is usually 25 to 600 nm and the height (depth of the pores) is 10 to 800 nm.
If the length of the holes in the direction parallel to the stretching direction extends longer than the wavelength of light, the polarized light in the direction parallel to the stretching direction of the obtained grid polarizing film is reflected. The length of the holes is usually 800 nm or more. The pitch, length, etc. of the pores can be appropriately adjusted depending on the thickness of the coating layer and the stretching conditions. Furthermore, by performing dry etching treatment on the surface of the porous structure film, the width of the layer partitioning the pores can be reduced.

In the present invention, the dry etching treatment may be performed before or after any step. However, since the porous structure becomes brittle by the treatment, it is preferably performed after the stretching treatment. Moreover, a general method can be used as dry etching. For example, techniques such as ion etching, plasma etching, radical etching, reactive ion etching (RIE), reactive ion beam etching (RIBE), plasma ashing, and molecular beam etching can be used. Among these, plasma etching, reactive ion etching (RIE), and reactive ion beam etching (RIBE) are preferably used from the viewpoints of low damage, smoothness, etching vertical anisotropy, and productivity. As the dry etching _{gas, Ar, O 2, CF 4} , H 2, C 2 F 6, CHF 3, CH 2 F 2, CF 3 Br, N 2, NF 3, Cl 2, CCl 4, HBr, SF ₆ or the like can be used. Etching conditions can be adjusted as appropriate according to the dry etching gas used. Usually, the gas flow rate is 5 to 200 sccm, the gas pressure is 1 to 200 mTorr, the high frequency power is 100 to 20,000 W, and the substrate temperature is −60 to 90 ° C. It can be performed within a range. .

  In the production method of the present invention, the absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) is 1 before or after the porous structure film is stretched in one direction. A layer made of material Z of 0 or more is formed. The complex refractive index N is a theoretical relational expression of electromagnetic waves, and is expressed by N = n−iκ using the refractive index n of the real part and the extinction coefficient κ of the imaginary part.

  The material Z can be appropriately selected from materials in which either the real part or the imaginary part of the complex refractive index is large and the absolute value of the difference is 1.0 or more. Specific examples of the material Z include metals; inorganic semiconductors such as silicon and germanium; conductive polymers such as polyacetylene, polypyrrole, polythiophene, and poly-p-phenylene; and conductive resins such as iodine, boron trifluoride, and five fluorine. Organic conductive materials doped with dopants such as arsenic phosphide and perchloric acid; organic-inorganic composite conductive materials obtained by drying a solution in which conductive metal fine particles such as gold and silver are dispersed in an insulating resin Materials, etc. Among these, a metal material is preferable from the viewpoints of productivity and durability of the grid polarizing film. In order to efficiently separate light in the visible range, each of the real part n and the imaginary part κ of the complex refractive index at a temperature of 25 ° C. and a wavelength of 550 nm is preferably n of 4.0 or less and κ of 3. 0 or more and the absolute value of the difference | n−κ | is 1.0 or more, more preferably n is 2.0 or less, κ is 4.5 or more, and | n−κ | .0 or more. Examples of the preferable range include silver, aluminum, chromium, indium, iridium, magnesium, palladium, platinum, rhodium, ruthenium, antimony, and tin. Examples of the more preferable range include aluminum, indium. , Magnesium, rhodium, tin and the like. In addition to the above, a material in which n is 3.0 or more and κ is 2.0 or less, preferably a material in which n is 4.0 or more and κ is 1.0 or less is also preferably used. be able to. Examples of such a material include silicon.

Although the details are unknown, the value of | n−κ | has the following significance. First, in the case of n <κ, it is shown that κ is larger and n is smaller. The larger κ is, the higher the conductivity is. When the conductivity is large, the number of free electrons that can vibrate in the stretched direction increases, so the electric field generated by the incidence of polarized light (polarized light in a direction parallel to the stretch direction (electric field)) becomes stronger, and the reflectance for the polarized light increases. . Since the width in the direction orthogonal to the stretching direction is small, electrons do not move in that direction, and the above effect does not occur for polarized light in the direction orthogonal to the stretching direction, and the polarized light is transmitted. In addition, since the wavelength of incident light in the medium where n is smaller becomes larger, the size of the porous structure (line width, pitch, etc.) becomes relatively smaller, and is less susceptible to scattering, diffraction, etc. The transmittance (polarized light in a direction perpendicular to the stretching direction) and the reflectance (polarized light in a direction parallel to the stretching direction) are increased.
On the other hand, in the case of n> κ, it is shown that n is larger and κ is smaller. As n is larger, the difference between the refractive index of the hole portion (air) and the refractive index of the portion surrounding the hole becomes larger, and structural birefringence is more likely to appear. On the other hand, if κ is large, light absorption increases, so it is preferable that κ is small in order to prevent light loss.

The method for forming the layer made of the material Z is not particularly limited. Depending on the materials used, various coatings by vacuum deposition processes such as vacuum deposition, sputtering, and ion plating, and wet processes such as microgravure, screen coating, dip coating, electroless plating, and electrolytic plating Can be used.
Further, the layer made of the material Z is an amine compound as described in JP-A No. 2004-6197, JP-A No. 2004-303783, JP-A No. 2005-146308, JP-A No. 2005-206925, and the like. It is also possible to use a method of forming aluminum by applying a complex of silane and alane and further heat and / or light treatment.

  FIG. 3 is an enlarged view of the porous structure film after the layer made of the material Z is formed. It can be seen that the layer made of the material Z is formed on the top surface of the layer that completely fills the holes.

  In the production method of the present invention, it is preferable to form the transparent protective layer after forming the layer made of the material Z. The protective layer can be formed before or after stretching in one direction.

The transparent protective layer may be a layer made of a transparent resin or a layer made of an inorganic compound. Examples of the resin constituting the layer made of the transparent resin may include the same resins as those exemplified as the resin constituting the base material. As for the inorganic compound which comprises the layer which consists of an inorganic compound, an inorganic oxide, inorganic nitride, fluoride, etc. are mentioned.
The transparent protective layer is not particularly limited depending on the formation method. For example, methods such as laminating a film made of a resin, applying a resin solution and drying, applying a photocurable solution and photocuring, and depositing an inorganic compound are included.

When forming the transparent protective layer, the pores of the porous structure film may be filled with a material forming the transparent protective layer, or a space may be secured without being filled.
When a space is secured without filling the pores of the porous structure film, it is preferable that the space contains air or an inert gas. When air or an inert gas is included in the space, the polarization rate of the grid polarizing film increases. Examples of the inert gas include nitrogen and argon.
When filling the pores of the porous structure film, it is preferable to use a material having a low refractive index as the transparent protective layer. For example, inorganic compounds, such as magnesium fluoride, a porous substance, etc. are mentioned. In the present invention, a porous material is preferred.

  The porous material used in the present invention is a transparent porous material in which minute pores are dispersed in a matrix. Most of the pores in the porous material are 200 nm or less, and the content of the pores is usually 10 to 60% by volume, preferably 20 to 40% by volume. Porous materials include silica airgel and porous bodies in which hollow particles are dispersed in a matrix. Air or an inert gas is usually sealed in the pores in the porous material.

Silica aerogel is produced by hydrolysis of alkoxysilane as disclosed in U.S. Pat. No. 4,402,927, U.S. Pat. No. 4,432,956 and U.S. Pat. No. 4,610,863. The gel compound composed of the silica skeleton obtained by the polymerization reaction can be produced by wetting with a solvent (dispersion medium) such as alcohol or carbon dioxide, and removing the solvent by supercritical drying. Silica airgel is manufactured in the same manner as described above using sodium silicate as a raw material as disclosed in US Pat. No. 5,137,279, US Pat. No. 5,124,364, and the like. Can do.
Examples of the porous body in which hollow fine particles are dispersed in a matrix include porous bodies as disclosed in Japanese Patent Application Laid-Open Nos. 2001-233611, 2002/021259, and 2003-149642. Can be mentioned.

The grid polarizing film obtained by the production method of the present invention has a property of transmitting one of orthogonal linearly polarized light and reflecting the other. By utilizing this property, the luminance of the liquid crystal display device can be improved.
For example, various functions can be provided by superimposing the grid polarizing film obtained by the production method of the present invention on another optical film. Examples of other optical films include an absorbing polarizing film, a retardation element, and a polarizing diffraction element. In particular, when the grid polarizing film of the present invention is used for improving the luminance of a liquid crystal display device, the other optical film is preferably an absorption polarizing film.

  The absorptive polarizing film used in the present invention transmits one of two linearly polarized light intersecting at right angles and absorbs the other. For example, a hydrophilic polymer film such as a polyvinyl alcohol film or an ethylene vinyl acetate partially saponified film adsorbed a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, the hydrophilic polymer film Examples include uniaxially stretched and dichroic substances adsorbed, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. The thickness of the absorptive polarizing film is usually 5 to 80 μm.

  The grid polarizing film and the absorption polarizing film are preferably overlapped so that the transmission axis of the grid polarizing film and the transmission axis of the absorption polarizing film are substantially parallel. With such an arrangement, natural light can be efficiently converted into linearly polarized light.

  The method for superimposing the grid polarizing film and another optical film is not particularly limited. For example, while simultaneously pulling out the long grid polarizing film wound in a roll shape and another long polarizing optical film wound in a roll shape from the roll, the grid polarizing film and the other optical film are The method including making it closely_contact | adhere is mentioned. An adhesive may be interposed between the grid polarizing film and another optical film. As a method for bringing the grid polarizing film and another optical film into close contact with each other, there is a method in which the grid polarizing film and the other optical film are pressed together and sandwiched between nips of two parallelly arranged rolls.

  The liquid crystal display device of this invention is equipped with the said grid polarizing film. The liquid crystal display device includes a liquid crystal cell whose polarization transmission axis can be changed by adjusting a voltage, and two absorptive polarizing films arranged so as to sandwich the liquid crystal cell. In order to send light to the liquid crystal cell, a backlight device is provided for the transmissive liquid crystal display device and a reflector is provided for the reflective liquid crystal display device on the back side of the display surface.

  In the transmission type liquid crystal display device of the present invention, when the grid polarizing film of the present invention is disposed between the backlight device and the liquid crystal cell, the light emitted from the backlight device is separated into two linearly polarized light by the grid polarizing film. Then, one linearly polarized light returns in the direction of the liquid crystal cell, and the other linearly polarized light returns in the direction of the backlight device. The backlight device is usually provided with a reflecting plate, and the linearly polarized light returning to the direction of the backlight device is reflected by the reflecting plate and returns to the grid polarizing film again. The returned light is again separated into two polarized light by the grid polarizing film. By repeating this, the light emitted from the backlight device is effectively used. As a result, light such as a backlight can be efficiently used for displaying images on the liquid crystal display device, and the screen can be brightened. In the reflective liquid crystal display device, the screen can be brightened by the same principle.

Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. Parts and% are based on mass unless otherwise specified.
(Evaluation methods)
1) Weight average molecular weight of polymer Measured by gel permeation chromatography (GPC) using cyclohexane (toluene when the resin was not dissolved) as a solvent.
2) Hydrogenation rate, modification amount, amide group content, cyclization rate of alicyclic structure polymer
Measurement was performed by a conventional method using ¹ H-NMR.
3) Evaluation of brightness improvement effect The obtained long grid polarizing film was punched into a predetermined shape to obtain a single-wafer grid polarizing film. A light diffusing sheet and the grid polarizing film were sequentially laminated on the light exiting side of the light guide plate in which the cold cathode tube was disposed on the incident end face side and the light reflecting sheet was provided on the back side, thereby producing a polarized light source device. Furthermore, the absorption type polarizing plate is laminated so that the transmission axis of the absorption type polarizing plate is the same as the transmission axis of the grid polarizing film, and the transmission type TN liquid crystal display element and the absorption type polarizing plate are absorbed by the absorption type under the liquid crystal display element. A liquid crystal display device was manufactured by sequentially arranging the polarizing plates in a direction perpendicular to the transmission axis of the polarizing plate. The front luminance at the time of bright display of the obtained liquid crystal display device was measured using a luminance meter (trade name: BM-7, manufactured by Topcon Corporation).

Production Example (Manufacture of an alicyclic structure polymer having an amide group (amphiphilic polymer))
Under a nitrogen atmosphere, 500 parts of dehydrated cyclohexane was mixed with 0.82 part of 1-hexene, 0.15 part of dibutyl ether and 0.30 part of triisobutylaluminum in a reactor at room temperature. 9-ethylidene-tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-4-ene (hereinafter abbreviated as “ETCD”) 100 parts and 40 parts of tungsten hexachloride 0.7% toluene solution were continuously added and polymerized over 2 hours. To the polymerization solution, 1.06 part of butyl glycidyl ether and 0.52 part of isopropyl alcohol were added to deactivate the polymerization catalyst, and the polymerization reaction was stopped to obtain a reaction solution containing an ETCD ring-opening polymer.

  To 100 parts of the reaction solution containing the ETCD ring-opening polymer obtained above, 270 parts of cyclohexane is added, and further 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) is added as a hydrogenation catalyst, and 5 MPa with hydrogen. Pressure. The mixture was heated to 200 ° C. with stirring and reacted for 4 hours to obtain a reaction solution containing 20 wt% of ETCD ring-opening polymer hydride. The hydrogenation catalyst is removed by filtration, and the hydride is melted while removing the solvent cyclohexane and other volatile components at a temperature of 270 ° C. and a pressure of 1 kPa or less using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.). Were extruded into a strand form from an extruder, and the cooled strand was cut to obtain ETCD ring-opened polymer hydride pellets. The obtained ETCD ring-opening polymer hydride had a weight average molecular weight of 35,000 and a hydrogenation rate of 99.9%.

  Subsequently, 10.0 parts of maleic anhydride, 2 parts of dicumyl peroxide, and 250 parts of tert-butylbenzene were mixed with 100 parts of the ETCD ring-opening polymer hydride obtained above, and 135 ° C. in an autoclave. And allowed to react for 6 hours. A solid was precipitated by pouring the reaction solution into a large amount of acetone, and the solid was separated by filtration. The solid was dried at 100 ° C. and 1 Torr or less for 48 hours to obtain 103 parts of a maleic anhydride-modified alicyclic structure polymer. The resulting maleic anhydride-modified alicyclic structure polymer had a weight average molecular weight of 39,000 and a maleic anhydride-modified amount of 19.5 mol%.

  Subsequently, 8.0 parts of diethylamine and 400 parts of toluene were mixed with 100 parts of the maleic anhydride-modified alicyclic structure polymer, and the reaction was carried out until the peak derived from the acid anhydride disappeared by IR. Thereafter, the solid was precipitated by pouring into a large amount of acetone, and the solid was recovered by filtration. The collected solid was dried at 100 ° C. and 1 Torr or less for 48 hours to obtain 99 parts of an alicyclic structure polymer having an amide group. The obtained alicyclic structure polymer having an amide group had a weight average molecular weight of 39,000 and an amide group content of 19.5 mol%.

Example 1 (Honeycomb production → stretching → deposition → protection layer formation)
A silica fine particle slurry was prepared by mixing 14.8 parts of methyl ethyl ketone slurry (solid content concentration: 30% by mass) of silica fine particles having a maximum particle size of 20 nm and 29.6 parts of tetrahydrofuran. Next, 10 parts of an alicyclic structure polymer (amphiphilic polymer) having an amide group obtained in Production Example in a four-necked flask equipped with a stirrer, thermometer, DeanStarkTrap, reflux condenser and nitrogen gas introduction tube, polar 30 parts of an alicyclic structure polymer having no group (hydrophobic polymer, trade name: ZEONEX 480R, manufactured by Nippon Zeon Co., Ltd.) and 1000 parts of cyclohexane were mixed and stirred until uniform. Subsequently, 44.4 parts of the silica fine particle slurry obtained above was added while stirring the toluene solution. Methyl ethyl ketone, tetrahydrofuran and cyclohexane were removed at 90 ° C. and concentrated until the solid content concentration became 5% to obtain 860 parts of an alicyclic structure polymer composition solution.

While drawing the film from the wound body of a long transparent resin film (registered trademark: “ZEONOR FILM” ZF-14, manufactured by Nippon Zeon Co., Ltd.), the alicyclic structure polymer composition solution was dried to a thickness of 7 μm. And then dried under conditions of room temperature and humidity of 70%, further dried at 100 ° C. for 5 minutes to remove the solvent, and finally wound up on a winding core to obtain a porous material as shown in FIG. A long roll of film K having a structure was obtained.
As shown in FIG. 2, the film is drawn continuously from the roll of the film K having a long porous structure while being drawn twice at a drawing temperature of 140 ° C. in the film flow direction. A wound body of a long film L having a porous structure having anisotropy was obtained.

Next, while pulling out the film from the wound body of the film L, aluminum is continuously deposited on the film, and then a triacetyl cellulose film is continuously laminated on the surface of the aluminum film and is bonded by pressing with a pressure roller. They were combined and wound on a winding core to obtain a wound body of a long grid polarizing film 1. The SEM image of the aluminum vapor deposition surface of the obtained grid polarizing film 1 is shown in FIG. 3, and it can be seen that a structure is formed in which aluminum lines having a width of about 100 nm are arranged substantially in parallel.
When the front luminance of the obtained grid polarizing film 1 was measured, the front luminance was 198 cd / m ² .

Example 2 (Honeycomb production → deposition → protection layer formation → stretching treatment)
While drawing the film from the roll of film K obtained in Example 1, aluminum was continuously deposited on the film, and a triacetyl cellulose film was continuously laminated on the aluminum film surface. Subsequently, it was pressed and bonded with a pressure roller, wound around a core, and a wound body of a long laminate having an aluminum layer and a triacetylcellulose layer on a porous structure was obtained. Next, while pulling out the laminate from the wound body of the laminate, it is continuously stretched three times at a stretching temperature of 140 ° C. in the film flow direction, and wound on a core to form a long grid polarizing film 2. A wound body of was obtained. The obtained grid polarizing film 2 formed a structure in which aluminum wires having a width of about 80 nm were arranged substantially in parallel.
When the front luminance of the obtained grid polarizing film 2 was measured, the front luminance was 205 cd / m ² .

Example 3 (Honeycomb production → stretching → dry etching → deposition → protection layer formation)
While pulling out the film from the wound body of the film L produced in Example 1, the film was subjected to oxygen etching treatment to further refine the porous structure having anisotropy. Next, aluminum was vapor-deposited on the oxygen-etched film, and a triacetyl cellulose film was superimposed on the aluminum film surface. The wound body of the long grid polarizing film 3 was obtained by pressure bonding with a pressure roller and bonding and winding on a core. The obtained grid polarizing film 3 formed a structure in which aluminum lines having a width of about 60 nm were arranged in parallel.
When the front luminance of the obtained grid polarizing film 3 was measured, the front luminance was 213 cd / m ² .

Comparative Example 1
A liquid crystal display device without a grid polarizing film was prepared. The front luminance of the obtained liquid crystal display device was 170 cd / m 2.

It is a figure which shows an example of the porous structure film | membrane obtained in the intermediate | middle stage of the manufacturing method of this invention. It is a figure which shows an example of the grid polarizing film obtained with the manufacturing method of this invention. 4 is an enlarged view showing an example of a grid polarizing film in which a layer made of material Z is formed. FIG.

Explanation of symbols

A: Hole B: Stretching direction

Claims (12)

Apply a solution of resin in an organic solvent on the substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
Then stretch in one direction,
Forming a layer made of the material Z having an absolute value of a difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) of 1.0 or more on the stretched porous structure film, Manufacturing method of grid polarizing film. Apply a solution of resin in an organic solvent on the substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
On the porous structure film, a layer made of the material Z having an absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) of 1.0 or more is formed.
Then, the manufacturing method of a grid polarizing film including extending | stretching to one direction.   Furthermore, the manufacturing method of the grid polarizing film of Claim 1 or 2 including forming a transparent protective film. Apply a solution of resin in an organic solvent on the substrate,
Evaporating the organic solvent and condensing water vapor to produce fine water droplets;
A porous structure film is obtained by evaporating the minute water droplets,
On the porous structure film, a layer made of the material Z having an absolute value of the difference between the real part n and the imaginary part κ of the complex refractive index (N = n−iκ) of 1.0 or more is formed.
A transparent protective film is formed on the layer made of the material Z,
Then, the manufacturing method of a grid polarizing film including extending | stretching to one direction.   The manufacturing method of the grid polarizing film in any one of Claims 1-4 which apply | coats the said solution in the environment of 70% or more of relative humidity.   Furthermore, the manufacturing method of the grid polarizing film in any one of Claims 1-5 including carrying out the dry etching process of the surface of a porous structure film.   The manufacturing method of the grid polarizing film in any one of Claims 1-6 whose material Z is a metal.   The manufacturing method of the grid polarizing film in any one of Claims 1-7 whose base material is a elongate thing.   The manufacturing method of the grid polarizing film of Claim 8 whose extending | stretching direction is substantially parallel to the vertical direction of a elongate base material.   The grid polarizing film obtained by the manufacturing method in any one of Claims 1-9.   A grid polarizing film obtained by the production method according to claim 8 or 9, and having a polarization transmission axis substantially parallel to the width direction of the elongated substrate. A liquid crystal display device comprising the grid polarizing film according to claim 10.

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