JP2007057876A - 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 superior in polarization-separating performance and has a high light transmittance, by using efficient, inexpensive and simple processes. <P>SOLUTION: According to the manufacturing method comprising a process of producing cracks on a B layer by stretching a stacked body that has an A layer made of resin, the B layer comprising a material Z having the absolute value of the difference between the real number part (n) and the imaginary number part (κ) of a complex refractive index (N=n-iκ) of 1.0 or larger and a D layer, which is disposed between the A layer and the B layer and has a micro domain structure comprising two kinds of X phase and Y phase, having different adhesiveness for the material Z, the grid polarization film in which a plurality of (b) layers extended slenderly and linearly comprising a material Z are arranged in parallel, while being separated from each other, can be obtained. <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 efficiency in an efficient and simple process. The present invention relates to a method for producing a grid polarizing film having transmittance.

  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 such a metal grid is formed, when the grid period is shorter than the wavelength of the incident light, the polarization component parallel to the linear metal forming the metal grid is reflected and the perpendicular polarization component is transmitted. It functions as a polarizer that creates single polarized light. It has been proposed that this grid polarizer is used as an optical component of an isolator in optical communication, and as a 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 polarizer 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 describes 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 phases having different glass transition temperatures are alternately connected in the stretching direction. Forming a composite film by forming a conductive thin film on one or both sides, stretching the composite film, and heat-fixing it to form a structure consisting of anisotropic conductive portions and polymer dielectric portions A method of manufacturing a polarizing optical element is disclosed.

JP 2001-74935 A JP 2005-148416 A

According to the study of the present inventor, the polarizing optical element obtained by the manufacturing method disclosed in Patent Document 1 has no regularity in the cracks of the metal thin film, and the metal thin film sometimes peels off from the substrate. For this reason, it has been difficult to obtain a polarizing optical element that sufficiently exhibits polarization separation performance. 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 liquid crystal display devices.
The objective of this invention is providing the method of manufacturing the grid polarizing film which has the high light transmittance which was excellent in polarization | polarized-light separation performance by an efficient and simple process.

The present inventor has found that 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 phases having different glass transition temperatures are alternately connected in the stretching direction have relatively few cracks. Although it is suitable for regular generation, it has been found that the light transmittance is low.
Therefore, the inventor of the present invention includes an A layer made of resin and a material Z including a 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. And a D layer having a microdomain structure provided between the A layer and the B layer and having two types of X phase and Y phase having different adhesion to the material Z. A plurality of elongated and linearly extending b layers constituting the B layer are arranged side by side by an efficient and simple manufacturing method including causing the B layer to crack by stretching the laminate. The inventors have found that a grid polarizing film having a high light transmittance and an excellent polarization separation performance can be obtained, and have completed the present invention based on this finding.

Thus, according to the present invention,
(1) A layer made of resin;
A B layer comprising a material Z in which 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 1.0 or more;
A laminate having a microdomain structure provided between the A layer and the B layer and having two types of X phase and Y phase having different adhesion to the material Z; Including causing the B layer to crack by stretching,
There is provided a method for producing a grid polarizing film in which a plurality of elongated and linearly extending b layers constituting the B layer are arranged in a separated state.

Also according to the invention,
(2) A method for producing the grid polarizing film, further comprising forming at least one transparent protective layer on the b layer after stretching the laminate.
(3) The method for producing the grid polarizing film, further comprising forming at least one transparent protective layer on the B layer before stretching the laminate.
(4) The manufacturing method of the said grid polarizing film whose material Z is a metal,
(5) The manufacturing method of the said grid polarizing film whose metal is aluminum,
(6) In the stretching step, the stretching ratio R1 in the first stretching direction is 1.25 to 10 times, and the stretching ratio R2 in the second stretching direction orthogonal to the first stretching direction is 0.85. The method for producing the grid polarizing film, which is 2 times and the draw ratio R1 is larger than the draw ratio R2,
(7) The manufacturing method of the grid polarizing film in which the laminated body is long and is continuously stretched, and / or (8) the first stretching direction is substantially the same as the width direction of the long laminated body. A method of manufacturing the grid polarizing film, which is parallel, is provided.

Moreover, according to the present invention,
(9) Provided are a grid polarizing film obtained by the above manufacturing method, and (10) a grid polarizing film obtained by the above manufacturing method and having a polarization transmission axis substantially parallel to the width direction of the laminate. (11) A liquid crystal display device including the grid polarizing film is provided.

  The manufacturing method of the grid polarizing film of this invention combines the conventional resin molding method, the extending | stretching method, and film forming methods, such as a metal film, on predetermined conditions, and can be performed efficiently and simply. And the grid polarizing film obtained with the manufacturing method of this invention has high light transmittance, can isolate | separate natural light into two types of linearly polarized light, can reflect one side, and can permeate | transmit another side. 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 luminance of the display screen can be improved.

In the present invention, an elongated linearly extending b layer containing a material Z having 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 is separated. A method for producing a grid polarizing film having a plurality of
A layer made of resin;
A B layer comprising a material Z in which 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 1.0 or more;
A laminate having a microdomain structure provided between the A layer and the B layer and having two types of X phase and Y phase having different adhesion to the material Z; It includes generating cracks in the B layer by stretching.

  The A layer of the laminate used in the method for producing the grid polarizing film of the present invention is not particularly limited as long as it is made of a transparent resin. As a transparent resin, it is preferable that the glass transition temperature of resin is 60-200 degreeC from a viewpoint of workability, and it is more preferable that it is 100-180 degreeC. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

  Specific examples of the transparent resin include polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene resin, polyvinyl chloride resin, cellulose diacetate, and cellulose triacetate. And alicyclic 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 ring-opening polymers described in JP-A-11-124429, and WO99 / 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 layer which consists of transparent resin 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 A layer 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. Moreover, the average thickness of A layer is 5 micrometers-1 mm normally from a viewpoint of handleability, Preferably it is 20-200 micrometers.
Further, the A layer is defined as a value in the retardation Re (Re = d × measured at that wavelength _{550nm (n x -n y),} n x, n y in-plane principal refractive index of the A layer; d is The average thickness of the A layer is not particularly limited. The difference in retardation Re (retardation unevenness) at any two points in the plane 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 D layer of the laminate used in the method for producing the grid polarizing film of the present invention is in close contact with a material Z in which the absolute value of the difference between the real part n and imaginary part κ of the complex refractive index (N = n−iκ) is 1.0 or more It has a microdomain structure having two types of X phase and Y phase having different properties.
The microdomain structure is a structure in which two types of incompatible X phase and Y phase are finely distributed. For example, a phase separation structure by a block copolymer or a phase separation by a blend of incompatible polymers. A structure can be used. The structure is classified into a sea-island structure, a cylinder structure, a spherical domain structure, a lamellar structure, and a gyroidal structure.
The X phase and the Y phase constituting the D layer are different in adhesion to the material Z constituting the B layer described later. The difference in adhesion to the material Z constituting the B layer is not particularly limited. For example, in a peel test performed with a grid of 100 squares, a difference of 10 squares or more is preferable, and a difference of 30 squares or more is present. It is more preferable.

  Examples of the material for forming the D layer include a block copolymer that forms a phase separation structure. Examples of the block copolymer include a linear block copolymer, a branched graft copolymer, and a star graft copolymer. From the viewpoint of productivity, a linear block copolymer and a branched graft copolymer are used. preferable. The block copolymer is obtained by polymerizing the corresponding monomer components in the order of each block by a technique such as radical polymerization, anionic polymerization, cationic polymerization, and living radical polymerization. The block copolymer is prepared by further polymerizing another monomer using a macroinitiator having a polymerization initiator added to the end of the polymer chain, or by adding a reactive group to the end of the polymer chain. It can also be obtained by reacting and bonding macromers. Furthermore, a resin obtained by further chemically modifying a block copolymer synthesized by the above-described method can be used in the present invention.

Examples of the block copolymer include a copolymer of polystyrene and polymethyl methacrylate, a copolymer of polybutadiene and polymethyl methacrylate, a copolymer of poly-2-vinylpyridine and polymethyl methacrylate, and polypropylene oxide and poly (methyl methacrylate). -Binary copolymers such as copolymers with ε-caprolactone; polystyrene-polymethyl methacrylate-polystyrene copolymer polystyrene-polybutadiene-polystyrene block copolymer (SBS copolymer), hydrogenated SBS copolymer ABA type ternary copolymers such as polystyrene-poly (ethylene-co-butylene) -polystyrene polystyrene copolymer (SEBS copolymer), polystyrene-polyisoprene-polystyrene block copolymer (SIS copolymer) Polymer; Polystyrene ABC-type terpolymers such as polystyrene-polybutadiene-polymethyl methacrylate copolymer, polystyrene-polyisoprene-polyglycidyl methacrylate copolymer: polystyrene-polymethyl methacrylate graft copolymer, polystyrene-ethylene oxide graft copolymer Branched graft copolymers such as polyethylene oxide-poly-ε-caprolactone star graft copolymer with pentaerythritol as a core molecule, polyethylene oxide-polylactide star graft copolymer with dipentaerythritol as a core molecule, etc. Can be mentioned.
Examples of other materials forming the D layer include a mixture of a polymer x and a polymer y, which have different adhesion to the material Z and are incompatible. For example, what mixed polymers, such as polymethylmethacrylate, with polystyrene, what mixed polymers, such as polybutadiene, with an alicyclic olefin polymer, etc. are mentioned.

  The D layer is formed on the main surface of the A layer. The method for forming the D layer is not particularly limited, and examples thereof include a method in which a material for forming the D layer is dissolved in a solvent to obtain a solution, and this solution is developed on the surface of the A layer in a film form. Examples of the method for developing the film include a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, a die coating method, and a gravure printing method.

  The solvent is not particularly limited, and examples thereof include aromatic hydrocarbons such as benzene, toluene, and xylene; linear or cyclic aliphatic hydrocarbons such as heptane and cyclohexane; chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane, and the like. Halogenated hydrocarbons; ethers such as dioxane and diethyl ether; ketones such as cyclohexanone and acetophenone; esters such as ethyl acetate and propiolactone; nitriles such as acetonitrile and benzonitrile; methanol, ethanol, n- Examples include alcohols such as propanol, isopropanol, n-butanol, sec-butanol; and other nitrobenzene and sulfolane. These can be used alone or as a mixture.

  The film constituting the D layer obtained by applying and drying the solution often exhibits a disordered and thermally unstable structure. This is because in the process of applying and drying the solution, the time required to complete the phase separation process between the components and form an ordered microdomain structure is insufficient. For this reason, after mounting D layer on a board | substrate, the said film | membrane is heat-processed as needed. By this heat treatment step, the layer separation structure can be further grown. The heat treatment temperature is preferably about the same as or higher than the highest glass transition temperature of each component constituting the D layer. The higher the heat treatment temperature, the shorter the time required for the heat treatment, but it is preferable to set it lower than the thermal decomposition temperature of the resin so as not to cause thermal degradation of the resin. For example, a film formed of a block copolymer made of polystyrene and polymethyl methacrylate is heat-treated at a temperature of 140 ° C. or higher, more preferably 190 to 270 ° C. for 10 minutes or longer. In order to prevent oxidative deterioration of the block copolymer film due to heating, it is preferable to perform heat treatment in an inert atmosphere or in vacuum.

  The average thickness of D layer is 0.1-500 micrometers normally, Preferably it is 1-50 micrometers. By setting the average thickness of the D layer within this range, a grid polarizing film having a high light transmittance can be easily obtained.

  The layer B of the laminate used in the method for producing a grid polarizing film of the present invention includes a material Z in which the absolute value of the difference between the real part n and imaginary part κ of the complex refractive index (N = n−iκ) is 1.0 or more. It is a waste. The B layer is formed on the main surface of the D layer. According to the manufacturing method of the present invention, by forming a crack in the B layer, it is possible to form a plurality of elongated and linearly extending b layers including the material Z, which are arranged apart from each other.

  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 polarized 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 such that n is 4.0 or less and κ is 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. 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.

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 and the more free electrons that can vibrate in the longitudinal direction of the b layer. Therefore, the electric field generated by the incidence of polarized light (polarized light in a direction parallel to the longitudinal direction of the b layer) is generated. It becomes stronger and the reflectance for the polarized light is increased. Since the width of the b layer is small, electrons do not move in the direction perpendicular to the longitudinal direction of the b layer, and the above effect does not occur for polarized light in the direction perpendicular to the longitudinal direction of the b layer. To do. In addition, since the wavelength in the medium of incident light is smaller when n is smaller, the size (line width, pitch, etc.) of the fine concavo-convex structure is relatively small, and is less susceptible to the effects of scattering, diffraction, Light transmittance (polarized light in a direction perpendicular to the b layer) and reflectance (polarized light in a direction parallel to the b layer) 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 increases, the difference in refractive index n between the b layer and the adjacent portion (air in FIG. 3) increases, and structural birefringence is more likely to occur. 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 this B layer 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. Of these, vacuum deposition and sputtering are preferred.

  FIG. 2 is a view showing an example of a laminate used in the production method of the present invention. In the laminate shown in FIG. 1, a D layer 18 having a microdomain structure is formed on an A layer 10 made of a transparent resin film, and a B layer 11 containing the material Z is further formed on the D layer. Is formed. The B layer can be easily obtained by forming a film by a method such as vapor deposition. The laminate before stretching has lengths XB and YB. This laminate is stretched in the first stretching direction 15.

  In the production method of the present invention, the laminate having the A layer, the D layer, and the B layer is stretched. By this stretching, a crack is generated in the B layer, and an elongated b layer including the material Z is formed. Although details of this formation mechanism are unknown, the present inventor presumes as follows. When a laminate having an A layer, a D layer, and a B layer is stretched, the B layer has a higher tensile stress than the A layer and the D layer. The Y layer having a weak adhesion with the B layer is less susceptible to the tensile stress of the B layer than the X phase having a strong adhesion with the B layer. For this reason, the Y phase (white portion in FIG. 1) with weak adhesion to the B layer is more distorted than the X phase (black portion in FIG. 1) with strong adhesion to the B layer. As a result, as shown in FIG. 1B, when a crack occurs in the B layer immediately above the Y phase in FIG. 1A, and the b layer is formed preferentially immediately above the X phase. Conceivable.

In the present invention, the stretching method is not particularly limited, but the stretching ratio R1 in the first stretching direction (= length after stretching XA / length before stretching XB) is preferably 1.25 to 10 times, particularly preferably. Is 1.5 to 3.0 times, and the draw ratio R2 in the second draw direction perpendicular to the first draw direction (= length YA after drawing / length YB before drawing) is preferably 0. It is preferable that the film is stretched so that the stretching ratio R1 is larger than the stretching ratio R2 (see FIGS. 1 and 3).
As a method for performing such stretching, for example, (i) the uniaxial stretching is performed while the shrinkage rate in the direction perpendicular to the stretching direction is suppressed to 15% or less, preferably 10% or less, more preferably 5% or less. And (ii) biaxial stretching. It is efficient and preferable to perform the stretching continuously using a long laminate.

In the stretching method (i), uniaxial stretching is performed by suppressing the contraction of the length in the direction perpendicular to the stretching direction to 15% or less against the force to shrink in the direction perpendicular to the stretching direction. The b layer can be formed without causing wrinkles. More specifically, the length XA after stretching in the uniaxial stretching direction (first stretching direction) is 1.25 to 10 times, preferably 1.5 to 3.0 times the length XB before stretching. The length YA after stretching in the direction orthogonal to the uniaxial stretching direction (second stretching direction) is 0.85 to 1.05 times, preferably 0.9 to 1.05 times the length YB before stretching, More preferably, it is 0.95 to 1.05 times.
A transverse uniaxial stretching method is a typical example of a method capable of stretching at such a magnification. The horizontal uniaxial stretching method is a method of stretching a long laminate in the width direction. A tenter stretching machine can be used as an apparatus for performing the horizontal uniaxial stretching method. When horizontal uniaxial stretching is performed, a crack is formed in the flow direction (MD direction) of the B layer, and a b layer elongated in the flow direction can be formed.

In the stretching method (ii), biaxial stretching is performed. In the biaxial stretching method, since the film is stretched in all the longitudinal and lateral directions, the laminate does not shrink and a b-layer without wrinkles can be formed. More specifically, the length XA after stretching in the first stretching direction is 1.25 to 10 times, preferably 1.5 to 3.0 times the length XB before stretching. The length YA after stretching in the second stretching direction orthogonal to the direction is 1 to 2 times, preferably 1.05 to 1.2 times the length YB before stretching, and is a length relative to the length XB before stretching. The laminate is stretched so that the length XA is larger than the length YA with respect to the length YB before stretching.
Biaxial stretching includes a sequential biaxial stretching method and a simultaneous biaxial stretching method, both of which are applicable. In the sequential biaxial stretching method, the longitudinal uniaxial stretching may be performed first, followed by the lateral uniaxial stretching, or the lateral uniaxial stretching may be performed first, and then the longitudinal uniaxial stretching may be performed.
In the simultaneous biaxial stretching method, a tenter simultaneous biaxial stretching machine is preferably used.

  For example, the stretching machine shown in FIG. 4 includes a plurality of gripping means 2 that grip the end of the laminate 1. The gripping means 2 is attached to an endless link device 3 (not shown in the figure, a part of the link and one endless link are omitted) composed of a plurality of equal length link devices formed in a fold shape. The endless link device 3 is driven by an inlet side sprocket 4 and an outlet side sprocket 9. The endless link device 3 travels from left to right in FIG. 4 and is guided by guide rails 5, 6, 7 and 8 arranged in a divergent shape. In FIG. 4, the interval in the width direction of the gripping means 2 gradually increases as the interval between the upper and lower guide rails increases. Further, since the distance between the upper and lower guide rails 6 and 8 is narrowed, the angle of the isometric link device is widened and the distance in the flow direction of the gripping means 2 is gradually increased. Both ends of the laminate 1 are gripped by the gripping means 2 at the entrance of the stretching machine, and are stretched simultaneously in two directions in the vertical and horizontal directions by increasing the spacing of the gripping means, and removed from the gripping means 2 at the exit of the stretching machine.

  In the biaxial stretching of the long laminate, the first stretching direction may be either the length direction or the width direction, but considering the stability in production, the first stretching direction is preferably the width direction. . By making the first stretching direction substantially parallel to the width direction (TD direction), a crack is formed in the flow direction (MD direction) of the B layer, and a b layer elongated in the flow direction can be formed.

The b layer formed by the crack of the B layer is elongated and linearly formed, and a plurality of the b layers are provided so as to be spaced apart from each other. For example, as shown in FIG. 3, a plurality of b layers 311 are stacked side by side. The pitch of the b layer is ½ or less of the wavelength of light used. The smaller the width and height of the b layer, the smaller the absorption of the polarization component in the transmission direction, which is preferable in terms of characteristics. In the grid polarizing film used for visible light, the pitch of the b layer is usually 50 to 1000 nm, the width of the b layer is usually 25 to 600 nm, and the height of the b layer is 10 to 800 nm. The b layer only needs to extend longer than the wavelength of normal light. The length of the b layer is preferably 800 nm or more. The height of the b layer can be adjusted by the thickness of the B layer. The length, pitch and width of the b layer can be adjusted by the stretching speed, the stretching temperature and the like.
Note that the b layer does not necessarily have the same shape and size as shown in FIG. 3, and may be any shape that has a longer side and a shorter side than the wavelength of light and a large aspect ratio. Also, the adjacent elongated and linearly extending b layers do not have to be completely separated from each other, and any layer may be used as long as they are partially separated. For example, an elongated and linearly extending b layer may be divided into two parts in the middle, or two elongated and linearly extending b layers may be combined in the middle and become one. Good.

  In the production method of the present invention, it is preferable to form at least one transparent protective layer on the B layer before stretching the laminate. Moreover, in the manufacturing method of this invention, after extending | stretching a laminated body, it is preferable to form at least 1 layer of transparent protective layers on the said b layer.

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 A layer. 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 the transparent protective layer is formed, the groove 312 between the b layers may be filled with a material forming the transparent protective layer, or a space may be secured without being filled. The groove 312 is a tear formed by a crack in the B layer.
When a space is secured without filling the groove, 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 groove, it is preferable to use a low refractive index substance 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 is a material having a large number of minute pores, and examples thereof include airgel. The airgel is a transparent porous body in which minute pores are dispersed in a matrix. The size of the pores is mostly 200 nm or less, and the content of the pores is usually 10 to 60% by volume, preferably 20 to 40% by volume. Aerogels include silica aerogels and porous bodies in which hollow particles are dispersed in a matrix. The air holes are usually sealed with air or inert gas.

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 polarizing element of the present invention is formed by superimposing the grid polarizing film and another polarizing optical film. Examples of other polarizing optical films include an absorbing polarizing film, a retardation element, and a polarizing diffraction element. In particular, when the polarizing element of the present invention is used as a brightness enhancement element of a liquid crystal display device, the other polarizing optical film is preferably an absorptive 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 polarizing element of this invention is not specifically limited by the manufacturing method. For example, the grid polarizing film and the other polarizing optical film while simultaneously unwinding the long grid polarizing film wound in a roll shape and another long polarizing optical film wound in a roll shape from the roll. And a method including adhering to each other. An adhesive can be interposed on the adhesion surface between the grid polarizing film and the other polarizing optical film. As a method for bringing the grid polarizing film and the other polarizing optical film into close contact with each other, there is a method in which the grid polarizing film and the other polarizing optical film are pressed together and sandwiched between nips of two parallelly arranged rolls.

  The liquid crystal display device of the present invention includes the grid polarizing film or the polarizing element. 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.

  The grid polarizing film of the present invention has a property of transmitting one of linearly polarized light orthogonal to each other and reflecting the other. Further, the polarizing element of the present invention has a property of transmitting one of orthogonal linearly polarized light and reflecting the other when irradiated with light from the grid polarizing film side. In the transmissive liquid crystal display device of the present invention, the grid polarizing film and the polarizing element of the present invention (arranged so that the grid polarizing film of the polarizing element is on the backlight side) are disposed between the backlight device and the liquid crystal cell. Then, the light emitted from the backlight device is separated into two linearly polarized light by the grid polarizing film, and one linearly polarized light returns to the liquid crystal cell and the other linearly polarized light returns to 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 an image 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.

Reference Example Aluminum was vapor-deposited on the surface of a 300 μm thick resin film so as to have a film thickness of 200 nm. 100 squares of 1 mm × 1 mm were created by making 1 mm pitch grid cuts in the aluminum film. An adhesive tape (manufactured by Nichiban Co., Ltd., CT24) was bonded onto the mass and pressed with the abdomen of the finger to bring it into close contact. Next, the adhesive tape was pulled in the direction of an angle of 90 degrees with respect to the main surface, and the adhesive tape was peeled off. The number of grids where the aluminum film was not peeled was counted.
In the polystyrene film, it was 5 squares out of 100 squares. On the other hand, in the polymethyl methacrylate film, it was 74 squares out of 100 squares. It was confirmed that polystyrene and polymethyl methacrylate have different adhesion to aluminum.

Example 1
Polystyrene-polymethyl methacrylate binary block copolymer (polystyrene block number average molecular weight: 52,000, polymethyl methacrylate block number average molecular weight: 52,000, weight average molecular weight / number average molecular weight = 1.1, Polymer Source Inc.) 5 parts was mixed with 95 parts of toluene and completely dissolved to obtain a coating solution.
Using an applicator with a gap of 100 μm, the coating solution was applied to a resin film having a thickness of 100 μm (trade name: ZEONOR film ZF-14, manufactured by Nippon Zeon Co., Ltd.), then dried at 110 ° C. for 5 minutes, and further 130 A resin substrate was obtained by heat treatment at 1 ° C. for 1 hour. The coating portion of the obtained resin substrate was cut into ultrathin sections using a LEICA ultramicrotome (ULTRACUT-UCT) manufactured by Hitachi High-Technology and stained with osmic acid. When the structure of the stained section was observed using a transmission electron microscope (H-7500) manufactured by Hitachi High-Technology, it was confirmed that the coating film had a lamellar structure with a width of about 30 nm (FIG. 5). reference). Furthermore, aluminum was vapor-deposited so that it might become a film thickness of 100 nm on the coating film surface of a resin base material.
Next, in an environment of 135 ° C., the film was stretched so that the length after stretching was 1.2 times in length and 0.9 times in width relative to the length and width before stretching. By this stretching, a crack was generated in the aluminum film, and a linear aluminum lattice was formed.
Subsequently, the protective film which consists of triacetylcellulose was adhere | attached on the aluminum lattice side with the urethane type adhesive agent, and the grid polarizing film was obtained.

A light diffusing sheet and the grid polarizing film cut out to a predetermined size (aluminum grid is light-emitting) are provided on the light exiting side of the light guide plate in which a cold cathode tube is disposed on the incident end face side and a light reflecting sheet is provided on the back side. A polarized light source device was manufactured by sequentially superposing the arrangement so as to be on the diffusion sheet side. Further, on the polarized light source device, an absorption type polarizing plate (arranged in parallel with the polarization transmission axis of the grid polarizing film), a transmission type TN liquid crystal display element, and an absorption type polarizing plate (polarization of the grid polarizing film). A liquid crystal display device was manufactured by sequentially superimposing the layers so as to be orthogonal to the transmission axis. When the front luminance of the obtained liquid crystal display device was measured using a luminance meter (trade name: BM-7, Topcon Corporation), the front luminance was 195 cd / m ² .

Example 2
Polymethyl methacrylate-polystyrene-polymethyl methacrylate ternary block copolymer (number average molecular weight of polymethyl methacrylate block: 137,000, number average molecular weight of polystyrene block: 13,000, weight average molecular weight / number average molecular weight = 1. 40, manufactured by Polymer Source Inc.) was mixed with 95 parts by weight of tetrahydrofuran and completely dissolved to obtain a coating solution.
The coating solution is applied onto a long resin film (trade name: ZEONOR film ZF-14, manufactured by Nippon Zeon Co., Ltd.) having a thickness of 100 μm, dried at 100 ° C. for 3 minutes, and further heat-treated at 130 ° C. for 10 minutes. Thus, a resin base material was obtained. When the structure of the coating film formed on the resin substrate was observed in the same manner as in Example 1, it was confirmed that the coating film portion formed a lamella structure having a width of about 45 nm.
Subsequently, aluminum was vapor-deposited on the surface of the obtained resin base material so as to have a film thickness of 100 nm. A triacetyl cellulose film was overlaid on the surface of the aluminum film, and was bonded by pressing with a pressure roller.
Next, the long grid polarizing film was obtained by carrying out horizontal uniaxial stretching at 135 degreeC by 1.2 time. The polarization transmission axis of this grid polarizing film was almost parallel to the width direction of the film.

Next, the rolled grid polarizing film, the rolled absorption polarizing film, and the long protective film made of triacetyl cellulose are each unwound from the roll and bonded with a urethane adhesive, Furthermore, the film was pressure-bonded with a pressure roller to obtain a film in which a grid polarizing film / absorptive polarizing film / triacetyl cellulose film was laminated in this order. A light diffusion sheet and the above-mentioned laminated film cut out to a predetermined size (the aluminum grating is used for light diffusion) on the light exit surface side of the light guide plate in which the cold cathode tube is disposed on the incident end surface side and the light reflecting sheet is provided on the back surface side. A polarized light source device was manufactured by sequentially superposing the arrangement so as to be on the sheet side. Further, on the polarized light source device, an absorption type polarizing plate (arranged in parallel with the polarization transmission axis of the grid polarizing film), a transmission type TN liquid crystal display element, and an absorption type polarizing plate (polarization of the grid polarizing film). A liquid crystal display device was manufactured by sequentially superimposing the layers so as to be orthogonal to the transmission axis. When the front luminance of the obtained liquid crystal display device was measured using a luminance meter (trade name: BM-7, Topcon Corporation), the front luminance was 200 cd / m ² .

Comparative Example 1
The polypropylene film was uniaxially stretched 4 times. Aluminum was deposited on the stretched film to a thickness of 100 nm. Next, the obtained film was further uniaxially stretched twice in the same stretching direction as the previous uniaxial stretching. By this stretching, a crack was generated in the aluminum film, and a linear aluminum lattice was formed.
Subsequently, the protective film which consists of triacetylcellulose was adhere | attached on the aluminum lattice side with the urethane type adhesive agent, and the grid polarizing film was obtained. When the luminance of this grid polarizing film was measured in the same manner as in Example 1, the front luminance was 165 cd / m ² .

It is a figure which shows the formation principle of b layer in the manufacturing method of this invention. It is a perspective view which shows an example of the laminated body used for the manufacturing method of this invention. It is a perspective view which shows an example of the grid polarizing film obtained by extending | stretching the laminated body of FIG. 2 according to the manufacturing method of this invention. It is a figure which shows an example of the tenter drawing machine used for this invention. It is a figure which shows an example of the micro domain structure (lamella structure) of D layer.

Explanation of symbols

1: Laminated body 2: Gripping means 3: Endless link device 4: Inlet side sprocket 9: Outlet side sprocket 5, 6, 7, 8: Guide rail 10: A layer 11: B layer 15: First extending direction 18: D layer 308: D layer 310 after stretching: A layer 311 after stretching: b layer 312: groove

Claims (11)

A layer made of resin;
A B layer comprising a material Z in which 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 1.0 or more;
A laminate having a microdomain structure provided between the A layer and the B layer and having two types of X phase and Y phase having different adhesion to the material Z; Including causing the B layer to crack by stretching,
A method for producing a grid polarizing film in which a plurality of thin and linearly extending b layers constituting the B layer are arranged in a separated state.   The manufacturing method of the grid polarizing film of Claim 1 which further includes forming at least 1 layer of transparent protective layers on the said b layer after extending | stretching a laminated body.   The manufacturing method of the grid polarizing film of Claim 1 which further includes forming at least 1 layer of transparent protective layers on the said B layer before extending | stretching a laminated body.   The manufacturing method of the grid polarizing film in any one of Claims 1-3 whose material Z is a metal.   The manufacturing method of the grid polarizing film of Claim 4 whose metal is aluminum.   In the stretching step, the stretching ratio R1 in the first stretching direction is 1.25 to 10 times, and the stretching ratio R2 in the second stretching direction orthogonal to the first stretching direction is 0.85 to 2 times. The manufacturing method of the grid polarizing film in any one of Claims 1-5 which there exists and draw ratio R1 is larger than draw ratio R2.   The manufacturing method of the grid polarizing film according to any one of claims 1 to 6, wherein the laminate is long and is continuously stretched.   The manufacturing method of the grid polarizing film of Claim 7 whose 1st extending | stretching direction is substantially parallel to the width direction of a elongate laminated body.   The grid polarizing film obtained by the manufacturing method in any one of Claims 1-8.   A grid polarizing film obtained by the production method according to claim 7 or 8, and having a polarization transmission axis substantially parallel to the width direction of the laminate. A liquid crystal display device provided with the grid polarizing film of Claim 9 or 10.

Images