JP2011090141A - Wire grid type polarizer and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire grid type polarizer that exhibits sufficient optical performance in a visible area, even when it has a protective layer, and to provide a method for manufacturing the same. <P>SOLUTION: In the method for manufacturing the wire grid type polarizer 1 that has a polarizer body 16 in which a plurality of metallic thin wires 12 are arranged in parallel with one another and a plurality of grooves 14 are formed along the metallic thin wires 12, on a light-transmissive substrate 10, and the protective layer 18 which covers the metallic thin wire 12 side surface of the polarizer body 16, the widths of the grooves 14 are made equal to one another from its bottom to its opening or are made wider gradually towards the opening from the bottom, a liquid curable composition whose surface tension at 25°C is 28 mN/m or less is applied to the metallic thin wire 12 side surface of the polarizer body 16, and the curable composition is cured to form the protective layer 18. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wire grid polarizer and a manufacturing method thereof.

  A wire grid type polarizer is known as a polarizer (also referred to as a polarization element or a polarization separation element) having polarization separation ability in the visible light region, which is used in an image display apparatus such as a liquid crystal display device, a rear projection television, or a front projector. It has been.

  The wire grid polarizer has a structure in which a plurality of fine metal wires are arranged in parallel to each other on a light-transmitting substrate. When the pitch of the fine metal wires is sufficiently shorter than the wavelength of the incident light, the component having an electric field vector orthogonal to the fine metal wires (that is, p-polarized light) in the incident light is transmitted and has an electric field vector parallel to the fine metal wires. (Ie s-polarized light) is reflected.

  In the wire grid type polarizer, even if the fine metal wire is slightly damaged, the performance of the wire grid type polarizer is affected. Moreover, the electrical conductivity of a metal fine wire falls by chemical changes, such as oxidation (production | generation of rust etc.), and the performance of a wire grid type polarizer may fall. Therefore, in order to suppress the damage and chemical change of the fine metal wire, the surface of the wire grid polarizer on the fine metal wire side may be covered with a protective layer.

  The protective layer is formed, for example, by applying a liquid curable resin composition to the surface of the wire grid polarizer on the metal thin wire side and curing the curable resin composition. However, when the liquid curable resin composition flows into the grooves formed between the fine metal wires and the grooves are filled with the protective layer, the optical characteristics of the wire grid polarizer are deteriorated.

  As a wire grid type polarizer in which the liquid curable resin composition does not easily flow into the grooves between the fine metal wires and the grooves are not easily filled with the protective layer, the width of the fine metal wires made of linear protrusions is 1 / height. One that is maximized on the protective layer side than the position 2 is proposed (Patent Document 1). The wire grid polarizer has a narrow protrusion between the protrusions by increasing the width of the protrusion on the protective layer side, so that the liquid curable resin composition does not easily flow into the groove. Since the opening of the groove is narrow, the optical properties, particularly the transmittance, of the wire grid polarizer are insufficient.

JP 2009-031537 A

  The present invention can easily form a wire grid polarizer and a protective layer that exhibit sufficient optical characteristics in the visible light region even if it has a protective layer, and the obtained wire grid polarizer is in the visible light region. Provides a method for manufacturing a wire grid polarizer exhibiting sufficient optical characteristics.

  The method of manufacturing a wire grid polarizer of the present invention includes a polarizer body in which a plurality of fine metal wires arranged in parallel to each other and a plurality of grooves along the fine metal wires are formed on a light-transmitting substrate; A wire grid type polarizer having a protective layer covering the surface of the metal body on the metal thin wire side, wherein the groove has the same width from the bottom of the groove to the opening, or the bottom of the groove The liquid curable composition having a surface tension at 25 ° C. of 28 mN / m or less is applied to the surface of the polarizer main body on the side of the fine metal wire, and gradually increases toward the opening. The protective layer is formed by curing the composition.

  In addition, the method of manufacturing the wire grid polarizer of the present invention includes a polarizer body in which a plurality of fine metal wires arranged in parallel to each other and a plurality of grooves along the fine metal wires are formed on a light-transmitting substrate; A wire grid type polarizer having a protective layer covering a surface of the polarizer main body on the metal thin wire side, wherein the groove has the same width from the bottom to the opening of the groove, or the groove The liquid curable composition having a viscosity at 25 ° C. of 5000 mPa · s or more is applied to the surface of the polarizer main body on the side of the fine metal wire and gradually increases from the bottom to the opening. The protective composition is formed by curing the adhesive composition.

The wire grid polarizer of the present invention is a wire grid polarizer obtained by the production method of the present invention, and the average filling rate of the protective layer into the groove defined below is 30% or less. It is characterized by being.
Average filling rate: Measure the height H1 from the bottom of the groove to the opening and the height H2 from the bottom of the groove to the protective layer, obtain the filling rate from the following formula (1), and calculate the filling rate in the five grooves. Averaged value.
Filling ratio = (H1-H2) / H1 × 100 (1).

The wire grid polarizer of the present invention exhibits sufficient optical characteristics in the visible light region even when it has a protective layer.
According to the method for producing a wire grid polarizer of the present invention, a protective layer can be easily formed, and the obtained wire grid polarizer exhibits sufficient optical characteristics in the visible light region.

It is sectional drawing which shows an example of the wire grid type polarizer of this invention. It is sectional drawing which shows the other example of the wire grid type polarizer of this invention. It is a perspective view which shows an example of a transparent substrate. It is sectional drawing which shows the other example of the wire grid type polarizer of this invention. It is sectional drawing which shows the other example of the wire grid type polarizer of this invention.

<Wire grid polarizer>
The wire grid polarizer of the present invention is a wire grid polarizer obtained by the manufacturing method of the present invention described later, and a plurality of fine metal wires arranged in parallel to each other on the light-transmitting substrate and the metal A polarizer body having a plurality of grooves along the fine line, and a protective layer covering the surface of the polarizer body on the metal fine wire side, the width of the groove is the same from the bottom of the groove to the opening, Alternatively, the width is gradually increased from the bottom of the groove toward the opening, and the average filling rate of the protective layer into the groove is 30% or less.

(Light transmissive substrate)
The light transmissive substrate is a substrate having light transmittance in the wavelength range of use of the wire grid polarizer. The light transmissive property means that light is transmitted, and the used wavelength range is specifically a range of 400 nm to 800 nm.

  Examples of the material for the light-transmitting substrate include a photo-curing resin, a thermoplastic resin, and glass. A photo-curing resin or a thermoplastic resin is preferable from the viewpoint that ridges can be formed by an imprint method described later. Photocuring resins are particularly preferred because they can form ridges by the printing method and are excellent in heat resistance and durability. The photocurable resin is preferably a photocurable resin obtained by photocuring a photocurable composition that can be photocured by photoradical polymerization from the viewpoint of productivity.

  The light transmissive substrate may be a laminate. As this laminated body, what has a base material which consists of a thermoplastic resin, glass etc., and the surface layer which has a protruding item | line which consists of photocuring resin formed in the surface of this base material is mentioned, for example.

(Metal fine wire)
The fine metal wires are formed by patterning a metal layer made of a metal or a metal compound formed on the surface of the light-transmitting substrate, or selectively on the surface of the ridge formed on the surface of the light-transmitting substrate. The thing etc. which formed the metal layer which consists of a metal or a metal compound are mentioned.
The plurality of fine metal wires only need to be formed substantially in parallel, and may not be formed completely in parallel. In addition, each thin metal wire is preferably a straight line that most easily exhibits optical anisotropy in the plane, but may be a curved line or a broken line as long as the adjacent thin metal wires do not contact each other.

  In the present invention, the term “ridge” refers to a portion that rises from the main surface of the light-transmitting substrate and that rises in one direction. The ridges may be made of the same material as the main surface portion of the light transmissive substrate that is integral with the main surface of the light transmissive substrate, or may be made of a light transmissive material different from the main surface portion of the light transmissive substrate. Good. The ridge is preferably integral with the main surface of the light-transmitting substrate and made of the same material as the main surface portion of the light-transmitting substrate, and is formed by molding at least the main surface portion of the light-transmitting substrate. It is preferable that it is a convex ridge.

  The shape of the cross-section in the direction perpendicular to the length direction and the main surface of the light-transmitting substrate is substantially constant over the length direction, and all of the cross-section shapes of the plurality of ridges are substantially constant. Preferably there is. The cross-sectional shape of the ridges is a shape having substantially the same width from the bottom (the main surface of the light-transmitting substrate) to the top, or a shape in which the width gradually decreases from the bottom to the top. Specific examples of the cross-sectional shape include a rectangle, a triangle, and a trapezoid. The cross-sectional shape may have a curved corner or side (side surface).

  In the present invention, the top portion of the ridge means a portion where the highest cross-sectional portion is continuous in the length direction. The top of the ridge may be a surface or a line. For example, when the cross-sectional shape is trapezoidal, the top portion forms a surface, and when the cross-sectional shape is triangular, the top portion forms a line. In the present invention, the surface other than the top of the ridge is referred to as a side surface of the ridge. Note that the surface between two adjacent ridges (the bottom surface of the ridge formed from the two adjacent ridges) is not the surface of the ridges, but is regarded as the main surface of the light-transmitting substrate.

  When a metal layer is formed on the surface of the ridge, the fine metal wire is composed of a metal layer extending in the length direction of the ridge. The metal layer may cover at least a part of the surface of the ridge. When the cross-sectional shape of the ridge is triangular or trapezoidal, the metal layer preferably completely covers the first side surface of the ridge. At this time, the metal layer may cover part or all of the top of the ridge, or may cover all of the top of the ridge and part or all of the second side surface of the ridge. . Further, the metal layer may cover a part of a surface between two adjacent ridges (a bottom surface of a groove formed from two adjacent ridges).

The material of the metal layer may be a metal material having sufficient conductivity, and is preferably a material that takes into consideration characteristics such as corrosion resistance. Examples of the metal material include a metal or a metal compound.
Examples of the metal include simple metals, alloys, metals containing dopants or impurities, and the like.
Specifically, aluminum, silver, chromium, magnesium, an aluminum alloy, a silver alloy, and the like can be given.
As the material of the metal layer, aluminum, an aluminum alloy, silver, chromium, and magnesium are preferable from the viewpoint of high reflectivity for visible light, low visible light absorption, and high conductivity, and aluminum and aluminum alloys. Is particularly preferred.

(groove)
In the present invention, the term “groove” refers to a space formed between the fine metal wires when the fine metal wires are formed by patterning a metal layer formed on the surface of the light-transmitting substrate. When the metal layer is selectively formed on the surface of the ridge formed on the surface of the transparent substrate, it refers to a space formed between the ridges and the projections that are formed by collecting the metal layers. In any case, the groove is formed along the fine metal wire.

  From the viewpoint of optical characteristics, the width of the groove is made the same from the bottom of the groove to the opening, or gradually increased from the bottom of the groove toward the opening. In the present invention, the bottom of the groove refers to the deepest part of the groove (usually the main surface of the light-transmitting substrate). In the present invention, the opening of the groove refers to a surface connecting the tops of the higher ones of the fine metal wires and the ridges. When the width of the groove is the same from the bottom to the opening, it may be substantially the same, and may not be completely the same. When the width of the groove is gradually increased from the bottom toward the opening, it is only necessary that the width is gradually increased, and there may be a portion where the width does not change in the middle.

(Protective layer)
The protective layer is a film-like layer extending along the surface on the metal fine wire side of the polarizer main body in a state in contact with the top of the metal fine wire and the ridge.

The filling of the protective layer into the groove is suppressed as much as possible from the viewpoint of optical characteristics. That is, the average filling rate of the protective layer into the groove defined below is 30% or less, preferably 25% or less, and more preferably 20% or less.
Average filling rate: The height H1 from the bottom of the groove to the opening and the height H2 from the bottom of the groove to the bottom of the protective layer are measured, and the filling rate is obtained from the following formula (1). The average filling rate.
Filling ratio = (H1-H2) / H1 × 100 (1).

The material of the protective layer is a cured resin obtained by curing a liquid curable composition described later.
Since the protective layer is present on the outermost surface of the wire grid polarizer, the protective layer preferably has a pencil hardness H or higher, and preferably has antifouling properties. Further, an antireflection structure (for example, an antireflection film) may be provided on the surface of the protective layer. Further, a hard surface layer or an antireflection structure may be provided on the back surface of the light transmitting substrate.

<Method for producing wire grid polarizer>
The manufacturing method of the wire grid polarizer can be divided into the following two methods depending on the difference in the method of forming the fine metal wires.
Method (I): A metal layer is formed on the surface of a flat light-transmitting substrate, the metal layer is patterned to form a fine metal wire, and then a polarizer main body is formed. A method for forming the protective layer by applying a liquid curable composition to be described later and curing the curable composition.
Method (II): A light-transmitting substrate having a plurality of ridges formed on the surface in parallel with each other at a predetermined pitch is produced, and a metal layer is selectively formed on the surface of the ridges to produce a polarizer body. Then, a liquid curable composition to be described later is applied to the surface of the polarizer main body on the side of the fine metal wires, and the protective layer is formed by curing the curable composition.

[Method (I)]
(Formation of fine metal wires)
The fine metal wire is formed by forming a metal layer on the surface of a flat light-transmitting substrate and patterning the metal layer.

  A vapor deposition method is mentioned as a formation method of a metal layer. Examples of the vapor deposition method include physical vapor deposition (PVD) and chemical vapor deposition (CVD), and vacuum vapor deposition, sputtering, and ion plating are preferred, and vacuum vapor deposition is particularly preferred.

  The patterning is performed by forming a resist pattern on the surface of the metal layer, etching the resist pattern as a mask to remove an excess metal layer, and then removing the resist pattern.

  The cross-sectional shape of the thin metal wire formed in the method (I) is generally a shape having a substantially same width from the bottom (main surface of the light-transmitting substrate) to the top, that is, a rectangle. Therefore, the width of the groove formed between the thin metal wires is substantially the same from the bottom of the groove to the opening.

(Formation of protective layer)
Examples of the method for applying the liquid curable composition include spin coating, dip coating, die coating, and spray coating.
Examples of the curing method include photocuring and heat curing.

A liquid curable composition having a surface tension at 25 ° C. of 28 mN / m or less is used. If the surface tension at 25 ° C. is 28 mN / m or less, the difference in surface tension with the metal is large, so that the liquid curable composition does not easily flow into the groove. The surface tension at 25 ° C. of the liquid curable composition is preferably 25 mN / m or less, and more preferably 24 mN / m or less.
The surface tension is measured by the Wilhelmy method using an automatic surface tension measuring machine DY-300 manufactured by Kyowa Interface Science. The Wilhelmy method is a method in which a sample such as a metal plate is immersed in a liquid whose surface tension is to be measured, and the resultant force of the surface tension and buoyancy generated at that time is measured.

In addition, even if it is a liquid curable composition in which the surface tension in 25 degreeC exceeds 28 mN / m, if the viscosity in 25 degreeC is 5000 mPa * s or more, a liquid curable composition does not flow easily into a groove | channel. Therefore, in this invention, you may use the liquid curable composition whose viscosity in 25 degreeC is 5000 mPa * s or more. The viscosity at 25 ° C. of the liquid curable composition is preferably 6000 mPa · s or more, and more preferably 7000 mPa · s or less.
The viscosity is measured at a temperature of 25 ° C. using a cone plate with a rotary viscometer.

The liquid curable composition contains a main agent, and if necessary, a curing agent, other additives, a solvent and the like.
Examples of the main agent include silicone resin, fluorosilicone resin, epoxy resin, acrylic resin and the like. When the liquid curable composition is a silicone resin, the surface of the protective film may be oxidized with oxygen plasma after curing to make the outermost surface of the protective layer inorganic.

[Method (II)]
(Production of light-transmitting substrate)
Examples of a method for manufacturing a light-transmitting substrate include an imprint method (an optical imprint method and a thermal imprint method), a lithography method, and the like. The imprinting method is preferable from the viewpoint of being able to be formed, and the optical imprinting method is particularly preferable from the viewpoint that the ridges can be formed with higher productivity and the groove of the mold can be accurately transferred.

  In the optical imprint method, for example, a mold in which a plurality of concave stripes are formed in parallel with each other at a predetermined pitch by a combination of electron beam drawing and etching is used. This is a method of transferring to a photocurable composition applied to the surface of the material and simultaneously photocuring the photocurable composition.

Specifically, the production of the light-transmitting substrate by the photoimprint method is preferably performed through the following steps (i) to (iv).
(I) The process of apply | coating a photocurable composition to the surface of a base material.
(Ii) A step of pressing a mold in which a plurality of concave stripes are formed in parallel with each other at a predetermined pitch against the photocurable composition so that the concave stripes are in contact with the photocurable composition.
(Iii) Radiation (ultraviolet ray, electron beam, etc.) is applied in a state where the mold is pressed against the photocurable composition to cure the photocurable composition and have a plurality of ridges corresponding to the mold ridges. Producing a light-transmitting substrate;
(Iv) A step of separating the mold from the light transmissive substrate.
In addition, what integrated the surface layer and base material which have a protruding item | line may be used as a light-transmitting substrate, and what separated the base material from the surface layer which has a protruding item | line may be used as a light-transmitting substrate. Moreover, after forming a metal layer, you may isolate | separate a base material from the surface layer which has a protruding item | line.

Specifically, the production of the light-transmitting substrate by the thermal imprint method is preferably performed through the following steps (i) to (iii).
(I) A step of forming a transfer film of a thermoplastic resin on the surface of a substrate, or a step of producing a transfer film of a thermoplastic resin.
(Ii) A mold in which a plurality of concave stripes are formed in parallel with each other at a constant pitch, and a glass transition temperature (Tg) or a melting point of a thermoplastic resin so that the concave stripes are in contact with the film to be transferred or the film to be transferred ( Tm) A process for producing a light-transmitting substrate having a plurality of protrusions corresponding to the recesses of the mold by pressing against the transfer film or transfer film heated above.
(Iii) A step of cooling the light transmissive substrate to a temperature lower than Tg or Tm to separate the mold from the light transmissive substrate.
In addition, what integrated the surface layer and base material which have a protruding item | line may be used as a light-transmitting substrate, and what separated the base material from the surface layer which has a protruding item | line may be used as a light-transmitting substrate. Moreover, after forming a metal layer, you may isolate | separate a base material from the surface layer which has a protruding item | line.

Examples of the mold material used for the imprint method include silicon, nickel, quartz glass, and resin. From the viewpoint of transfer accuracy, quartz glass and resin are preferable. Examples of the resin include a fluorine-based resin (ethylene-tetrafluoroethylene copolymer, etc.), a cyclic olefin, a silicone resin, an epoxy resin, an acrylic resin, and the like. From the viewpoint of mold accuracy, a photocurable acrylic resin is preferable. . The resin mold preferably has an inorganic film having a thickness of 2 to 10 nm on the surface from the viewpoint of repeated transfer durability. As the inorganic film, an oxide film such as SiO ₂ , TiO ₂ , and Al ₂ O ₃ is preferable.

  The cross-sectional shape of the groove of the polarizer body formed in the method (II) largely depends on the cross-sectional shape of the ridge of the light-transmitting substrate, that is, the cross-sectional shape of the groove of the mold. Therefore, in order to form a groove having the same groove width from the bottom to the opening, a mold having a rectangular cross-sectional shape is used. Further, in order to form a groove whose width gradually increases as it goes from the bottom to the opening, a mold having a triangular or trapezoidal cross-sectional shape is used.

  Films made of glass plates (quartz glass plates, non-alkali glass plates, etc.) and resins (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polydimethylsiloxane, transparent fluororesins, etc.) Etc. When a glass plate is used as the base material, the imprint method can be performed by a leaf type, and when a film is used as the base material, the imprint method can be performed by a roll-to-roll method.

(Formation of metal layer)
A vapor deposition method is mentioned as a formation method of a metal layer. Examples of the vapor deposition method include PVD and CVD, and vacuum vapor deposition, sputtering, and ion plating are preferable, and vacuum vapor deposition is particularly preferable. As the vapor deposition method, the oblique vapor deposition method by the vacuum vapor deposition method is most preferable because the incident direction of the fine particles to be attached to the light-transmitting substrate can be controlled and a metal or a metal compound can be selectively deposited on the surface of the ridge.

(Formation of protective layer)
Examples of the application method and the curing method of the liquid curable composition include the same methods as the method (I).
As a liquid curable composition, the thing similar to the thing quoted by the method (I) is mentioned.

<Embodiment of Wire Grid Type Polarizer>
Hereinafter, embodiments of the wire grid polarizer of the present invention will be described with reference to the drawings. The following diagram is a schematic diagram, and an actual wire grid polarizer does not have a theoretical and ideal shape as illustrated. For example, in an actual wire grid polarizer, there are some collapses in the shape of metal fine wires, ridges, and the like.
In addition, each dimension in this invention is taken as the value which measured and measured each dimension of five places in the scanning electron microscope image or transmission electron microscope image of the cross section of a wire grid type polarizer.

[First Embodiment]
FIG. 1 is a cross-sectional view showing a first embodiment of a wire grid polarizer of the present invention. In the wire grid polarizer 1, a plurality of fine metal wires 12 having a rectangular cross-sectional shape are parallel to each other via a bottom portion of a groove 14 formed between the fine metal wires 12 on a flat light-transmitting substrate 10. And a polarizer body 16 formed on the surface at a predetermined pitch Pp, and a protective layer 18 covering the surface of the polarizer body 16 on the metal thin wire 12 side.
In the wire grid polarizer 1, the width of the groove 14 is the same from the bottom to the opening.

  Pp is the sum of the width Dm of the fine metal wires 12 and the width of the grooves formed between the fine metal wires 12. Pp is preferably 300 nm or less, and more preferably 50 to 200 nm. When Pp is 300 nm or less, a high s-polarized reflectance is exhibited, and a high degree of polarization is exhibited even in a short wavelength region of about 400 nm. Moreover, the coloring phenomenon by diffraction is suppressed. Moreover, if Pp is 50 nm or more, high transmittance is exhibited.

The ratio of Dm and Pp (Dm / Pp) is preferably 0.1 to 0.7, and more preferably 0.25 to 0.55. When Dm / Pp is 0.1 or more, a high degree of polarization is exhibited. By setting Dm / Pp to 0.5 or less, coloring of transmitted light due to interference can be suppressed.
Dm is preferably 20 to 150 nm from the viewpoint of easily forming the fine metal wire 12.

  50-500 nm is preferable and, as for the height Hm of the metal fine wire 12, 100-300 nm is more preferable. When Hm is 50 nm or more, the polarization separation ability is sufficiently high. If Hm is 500 nm or less, the chromatic dispersion is small. Moreover, if Hm is 100-300 nm, it is easy to form the metal fine wire 12.

The thickness Hs of the light transmissive substrate 10 is preferably 0.5 to 1000 μm, and more preferably 1 to 40 μm.
The thickness H3 of the protective layer 18 is preferably 0.5 to 100 μm, and more preferably 1.0 to 30 μm.
The wire grid polarizer 1 can be manufactured by the method (I) described above.

[Second Embodiment]
FIG. 2 is a cross-sectional view showing a second embodiment of the wire grid polarizer of the present invention. In the wire grid polarizer 2, a plurality of ridges 20 having a rectangular cross-sectional shape are formed on the surface in parallel with each other at a predetermined pitch Pp through the bottoms of the ridges 22 formed between the ridges 20. Light-transmitting substrate 10, metal fine wire 12 made of a metal layer covering the entire surface of top 24 of ridges 20, and grooves 14 formed between the ridges 20 and the protrusions collecting the metal layers. The polarizer main body 16 and the protective layer 18 that covers the surface of the polarizer main body 16 on the metal thin wire 12 side are provided.
In the wire grid polarizer 1, the width of the groove 14 is the same from the bottom (bottom of the recess 22) to the opening.

  Pp is the sum of the width Dp of the ridges 20 and the width of the ridges 22. Pp is preferably 300 nm or less, and more preferably 50 to 200 nm. When Pp is 300 nm or less, a high s-polarized reflectance is exhibited, and a high degree of polarization is exhibited even in a short wavelength region of about 400 nm. Moreover, the coloring phenomenon by diffraction is suppressed. Moreover, if Pp is 50-200 nm, it will be easy to form a metal layer by vapor deposition.

The ratio of Dp to Pp (Dp / Pp) is preferably 0.1 to 0.7, and more preferably 0.25 to 0.55. If Dp / Pp is 0.1 or more, a high degree of polarization is exhibited. By setting Dp / Pp to 0.5 or less, coloring of transmitted light due to interference can be suppressed.
Dp is preferably 20 to 100 nm from the viewpoint of easily forming a metal layer by vapor deposition.

  50-500 nm is preferable and, as for the height Hp of the protruding item | line 20, 100-300 nm is more preferable. If Hp is 50 nm or more, the polarization separation ability is sufficiently high. If Hp is 500 nm or less, the wavelength dispersion of transmittance can be reduced. Moreover, if Hp is 50-500 nm, it will be easy to form a metal layer by vapor deposition.

  50-500 nm is preferable and, as for the height Hm of the metal fine wire 12 (metal layer), 100-300 nm is more preferable. When Hm is 50 nm or more, the polarization separation ability is sufficiently high. If Hm is 500 nm or less, the wavelength dispersion of the transmittance becomes small. Moreover, if Hm is 100 to 300 nm, it is easy to form a metal layer.

  The width Dm of the fine metal wire 12 (metal layer) is preferably 15 to 100 nm, and more preferably 20 to 80 nm. If Dm is 15 nm or more, the polarization separation ability is sufficiently high. If Dm is 100 nm or less, the transmittance is sufficiently high.

The thickness Hs of the light transmissive substrate 10 is preferably 0.5 to 1000 μm, and more preferably 1 to 40 μm.
The thickness H3 of the protective layer 18 is preferably 0.5 to 10 μm, and more preferably 1.0 to 30 μm.

The wire grid polarizer 2 can be manufactured by the method (II) described above.
As shown in FIG. 3, the fine metal wires 12 (metal layer) are substantially orthogonal to the length direction L of the ridges 20 and the first side surface 26 side with respect to the height direction H of the ridges 20. the metal or metal compound from a direction V1 constituting a 20-50 ° angle theta ^L, the amount of deposition can be formed by depositing the condition to be 15 to 100 nm.

Angle theta ^L, for example, can be adjusted by using the following vapor deposition apparatus.
Substantially perpendicular to the length direction L of the ridges 20, and the vapor deposition source is positioned on an extended line in a direction V1 at an angle theta ^L on the side of the first side surface 26 with respect to the height direction H of the ridge 20 The vapor deposition apparatus which can change the inclination of the transparent substrate 10 arrange | positioned facing a vapor deposition source.

[Third Embodiment]
FIG. 4 is a cross-sectional view showing a third embodiment of the wire grid polarizer of the present invention. In the wire grid polarizer 3, a plurality of ridges 20 having a triangular cross-sectional shape are formed on the surface in parallel with each other at a predetermined pitch Pp through the bottoms of the ridges 22 formed between the ridges 20. Light-transmitting substrate 10, the entire first side surface 26 of the ridge 20, a part of the bottom of the recess 22 adjacent to the first side surface 26, and the ridge adjacent to the first side surface 26. A polarizer main body 16 composed of a metal thin wire 12 made of a metal layer covering a part of the second side surface 20 of the 20 and a groove 14 formed between the ridges 20 and the protrusions formed by collecting the metal layers; and A protective layer 18 is provided to cover the surface of the polarizer body 16 on the side of the fine metal wires 12.
In the wire grid polarizer 2, the width of the groove 14 gradually increases from the bottom (bottom of the recess 22) toward the opening.

  Pp is the sum of the width Dbp of the bottom of the ridge 20 and the width of the bottom of the recess 22. Pp is preferably 300 nm or less, and more preferably 50 to 250 nm. When Pp is 300 nm or less, a high s-polarized reflectance is exhibited, and a high degree of polarization is exhibited even in a short wavelength region of about 400 nm. Moreover, the coloring phenomenon by diffraction is suppressed. Moreover, if Pp is 50-200 nm, it will be easy to form a metal layer by vapor deposition.

The ratio of Dbp to Pp (Dbp / Pp) is preferably 0.1 to 0.7, and more preferably 0.25 to 0.55. When Dbp / Pp is 0.1 or more, a high degree of polarization is exhibited. By setting Dbp / Pp to 0.5 or less, coloring of transmitted light due to interference can be suppressed.
Dbp is preferably 30 to 100 nm from the viewpoint of easily forming a metal layer by vapor deposition.

120-300 nm is preferable and, as for the height Hp of the protruding item | line 20, 80-270 nm is more preferable. If Hp is 120 nm or more, the polarization separation ability is sufficiently high. If Hp is 300 nm or less, the chromatic dispersion is small. Moreover, if Hp is 120-300 nm, it is easy to form a metal layer by vapor deposition.
The inclination angle θ1 of the first side surface 26 and the inclination angle θ2 of the second side surface 28 are preferably 30 to 85 °. θ1 and θ2 may be the same or different.
The thickness Hs of the light transmissive substrate 10 is preferably 0.5 to 1000 μm, and more preferably 1 to 40 μm.
The thickness H3 of the protective layer 18 is preferably 0.5 to 10 μm, and more preferably 1.0 to 30 μm.

Dm1 preferably satisfies the following formula (2).
0.2 × (Pp−Dbp) ≦ Dm1 ≦ 0.5 × (Pp−Dbp) (2).
If Dm1 is 0.2 × (Pp−Dbp) or more, high p-polarized light transmittance is exhibited and chromatic dispersion is small. When Dm1 is 0.5 × (Pp−Dbp) or less, the polarization separation ability is sufficiently high.

Hm1 is preferably 120 to 300 nm. If Hm1 is 120 nm or more, crystallization of the metal layer is suppressed and high s-polarized reflectance is exhibited.
Hm1 / Hp is preferably 1 to 2, and more preferably 1 to 1.5. If Hm1 / Hp is 1 or more, the polarization separation ability is improved. If Hm1 / Hp is 2 or less, the angle dependency of the optical characteristics is sufficiently low.

The wire grid polarizer 2 can be manufactured by the method (II) described above.
The metal thin wire 12 (metal layer) is substantially orthogonal to the length direction L of the ridges 20 and has an angle of 25 to 40 ° on the first side face 26 side with respect to the height direction H of the ridges 20. It can be formed by vapor-depositing a metal or metal compound from the direction V1 forming θ ^L under the condition that the vapor deposition amount is 40 to 60 nm.

[Fourth Embodiment]
FIG. 5 is a cross-sectional view showing a fourth embodiment of the wire grid polarizer of the present invention. In the wire grid type polarizer 4, a plurality of ridges 20 having a trapezoidal cross-sectional shape are formed on the surface in parallel with each other at a predetermined pitch Pp through the bottoms of the ridges 22 formed between the ridges 20. Light-transmitting substrate 10, the entire first side surface 26 of the ridge 20, a part of the bottom of the recess 22 adjacent to the first side surface 26, and the ridge 20 adjacent to the first side surface 26. Are formed between the metal thin wire 12 made of a metal layer covering the entire surface of the top 24, a part of the second side face 28 of the ridge 20 adjacent to the top 24, and the ridges 20 and the ridges formed by collecting the metal layers. And a protective layer 18 that covers the surface of the polarizer main body 16 on the metal wire 12 side.
In the wire grid polarizer 2, the width of the groove 14 gradually increases from the bottom (bottom of the recess 22) toward the opening.

In the fourth embodiment, the description of the same configuration as that of the wire grid polarizer 3 of the third embodiment is omitted.
The width Dtp of the top 24 of the ridge 20 is preferably equal to or less than half of Dbp, more preferably 40 nm or less, and further preferably 20 nm or less. If Dtp is less than or equal to half of Dbp, the transmittance will be higher and the angle dependency will be sufficiently low.

The fine metal wire 12 (metal layer) can be formed in the same manner as the fine metal wire 12 (metal layer) of the wire grid polarizer 3 of the third embodiment. When the thickness of the metal layer covering the top 24 of the ridge 20 is insufficient, the metal layer is substantially orthogonal to the length direction L of the ridge 20 and to the height direction H of the ridge 20. the metal or metal compound from a direction V2 constituting 25-40 ° angle theta ^R on the side of the second side 28, the amount of deposition may be deposited under conditions such that the 20nm or less.

  In the wire grid polarizer of the present invention described above, the cross-sectional shape of the plurality of grooves formed on the light transmissive substrate is the same from the bottom of the groove to the opening, or from the bottom to the opening. Since it is gradually widened as it goes, optical characteristics, particularly transmittance, is sufficiently high. Further, since the average filling rate of the protective layer into the groove is 30% or less, the deterioration of the optical characteristics is suppressed.

  Moreover, in the manufacturing method of the wire grid type polarizer of this invention demonstrated above, the liquid curable composition whose surface tension in 25 degreeC is 28 mN / m or less on the surface at the side of the metal fine wire of a polarizer main body. Alternatively, since a liquid curable composition having a viscosity at 25 ° C. of 5000 mPa · s or more is applied and the curable composition is cured to form a protective layer, the curable composition flows into the groove. It is difficult to fill the groove with a protective layer. As a result, the obtained wire grid type polarizer exhibits sufficient optical characteristics in the visible light region. Moreover, since the protective layer is formed by application | coating of a liquid curable composition, a protective layer can be formed simply.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
Examples 1 to 11 are examples, and examples 12 to 15 are comparative examples.

(Protective layer thickness)
The wire grid type polarizer was cut to a thickness of 30 nm with a microtome, and a projection image was taken with a transmission electron microscope (H-9500, manufactured by Hitachi, Ltd.) to measure the thickness H3 of the protective layer.

(Average filling rate)
The height H1 from the bottom of the groove to the opening and the height H2 from the bottom of the groove to the protective layer are measured simultaneously with the thickness H3 of the protective layer, and the filling rate is obtained from the following formula (1). The filling rate in the grooves was averaged.
Filling ratio = (H1-H2) / H1 × 100 (1).

(Transmittance)
The transmittance was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO, V-7200).
For the measurement, the attached polarizer is set between the light source and the wire grid polarizer so that the absorption axis is parallel to the major axis of the metal wire of the wire grid polarizer, and the surface of the wire grid polarizer is set. This was performed by applying polarized light from the side (surface side on which the fine metal wires were formed). The measurement wavelength was 550 nm.
The change of the p-polarized light transmittance after forming the protective layer with respect to the p-polarized light transmittance before forming the protective layer is less than 5% as S, 5% or more and less than 7% as A, 7% or more and less than 10% as B, X was 10% or more.

(Degree of polarization)
The degree of polarization was calculated from the following formula (4).
Polarization degree = ((Tp−Ts) / (Tp + Ts)) ^0.5 (4).
However, Tp is the p-polarized light transmittance at a wavelength of 550 nm, and Ts is the s-polarized light transmittance at a wavelength of 550 nm.
The change in the degree of polarization after forming the protective layer with respect to the degree of polarization before forming the protective layer is less than 5%, S is 5% or more and less than 8%, A is 8% or more and less than 10%, and 10% or more. X.

(Preparation of photocurable composition 1)
To a 1000 mL four-necked flask equipped with a stirrer and a condenser,
60 g of monomer 1 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-DPH, dipentaerythritol hexaacrylate),
40 g of monomer 2 (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester A-NPG, neopentyl glycol diacrylate),
4.0 g of photopolymerization initiator (manufactured by Ciba Specialty Chemicals, IRGACURE907),
Fluorine-containing surfactant (manufactured by Asahi Glass Co., Ltd., co-oligomer of fluoroacrylate (CH ₂ ═CHCOO (CH ₂ ) ₂ (CF ₂ ) ₈ F) and butyl acrylate), fluorine content: about 30% by mass, mass average molecular weight: About 3000) 0.1 g,
1.0 g of a polymerization inhibitor (Q1301 manufactured by Wako Pure Chemical Industries, Ltd.) and 65.0 g of cyclohexanone were added.

  The flask was stirred and homogenized for 1 hour at room temperature and in a light-shielded state. Next, 100 g (solid content: 30 g) of colloidal silica was slowly added while stirring in the flask, and the mixture was further homogenized by stirring for 1 hour while keeping the temperature of the flask at room temperature and light shielding. Next, 340 g of cyclohexanone was added, and the solution was stirred for 1 hour with the inside of the flask at room temperature and light-shielded to obtain a solution of the photocurable composition 1.

(Manufacture of polarizer body 1)
The photocurable composition 1 was applied to the surface of a polyethylene terephthalate (PET) substrate (A4300, manufactured by Toyobo Co., Ltd.) having a thickness of 188 mm by a spin coating method, and a coating film of the photocurable composition 1 having a thickness of 1 μm was applied. Formed.

  A quartz glass transparent mold (area: 150 mm × 150 mm, pattern area: 100 mm × 100 mm, groove pitch Pp: 140 nm, groove Width Dp: 70 nm, groove depth Hp: 150 nm, groove cross-sectional shape: rectangular), 0.5 MPa (gauge) at 25 ° C. so that the groove is in contact with the coating film of the photocurable composition 1 Pressure) against the coating film of the photocurable composition 1.

  While maintaining this state, light from a high-pressure mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light: irradiation energy at 255 nm, 315 nm, 365 nm, and 365 nm: 1000 mJ) is irradiated for 15 seconds from the transparent mold side. The curable composition 1 is cured to form a light-transmitting substrate 1 having a plurality of ridges corresponding to the ridges of the transparent mold (ridge pitch Pp: 140 nm, ridge width Dp = 70 nm, ridge height (Hp = 150 nm, cross-sectional shape of ridge: rectangle). The transparent mold was slowly separated from the light transmissive substrate 1.

Using a vacuum vapor deposition apparatus (SEC-16CM, manufactured by Showa Vacuum Co., Ltd.) that can change the inclination of the light transmissive substrate facing the vapor deposition source, aluminum is vapor-deposited by oblique vapor deposition on the ridges of the light transmissive substrate, A polarizer main body 1 was obtained in which a metal layer (metal fine wire) was formed and a PET substrate was adhered to the back surface.
At this time, a direction V1 that is substantially orthogonal to the length direction L of the ridge and forms an angle θ ^L on the first side surface with respect to the height direction H of the ridge (that is, the first side surface side). ) Was deposited once. The angle θ ^L in the vapor deposition was 35 °, and the thickness Hm ′ of the metal layer formed in a flat region where no protrusion was formed by the vapor deposition was 50 nm. Hm ′ was measured by a film thickness monitor using a crystal resonator as a film thickness sensor.

(Manufacture of polarizer body 2)
A quartz glass mold (area: 150 mm × 150 mm, pattern area: 100 mm × 100 mm, groove pitch Pp: 160 nm, groove bottom width Dbp: parallel to each other and formed at a predetermined pitch) 65 nm, groove height Hp: 200 nm, θ1 and θ2: 80.8 °, groove length: 100 mm, groove cross-sectional shape: substantially isosceles triangle) In the same way, a light-transmitting substrate 2 having a plurality of ridges corresponding to the ridges of the transparent mold (ridge pitch Pp: 160 nm, ridge bottom width: Dbp: 65 nm, ridge height Hp : 200 nm, θ1 and θ2: 80.8 °, protrusion length: 100 mm, protrusion cross-sectional shape: substantially isosceles triangle). The transparent mold was slowly separated from the light transmissive substrate 2.

Polarization is performed except that the light-transmitting substrate 2 is used, the angle θ ^L in vapor deposition is set to 30 °, and the thickness Hm ′ of the metal layer formed in the flat region where no protrusion is formed by vapor deposition is set to 55 nm. A polarizer main body 2 having a PET base material attached to the back surface was obtained in the same manner as the main body 1.

(Curable resin for protective layer formation)
The following were prepared as curable trees for forming the protective layer.

(Preparation of acrylic resin 1)
In a vial container (inner volume 6mL),
0.55 g of modified bisphenol A diacrylate (manufactured by Daicel-Cytec, EBECRYL150),
0.45 g of 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., HDDA),
0.04 g of photopolymerization initiator (Ciba Specialty Chemicals, IRGACURE907)
Were mixed and acrylic resin 1 was prepared.

(Preparation of acrylic resin 2)
In a vial container (inner volume 6mL),
0.40 g of modified bisphenol A diacrylate (Daicel Cytec, EBECRYL150),
0.40 g of 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., HDDA),
0.2 g of isobornyl acrylate (manufactured by Aldrich),
0.04 g of photopolymerization initiator (Ciba Specialty Chemicals, IRGACURE907)
Were mixed and acrylic resin 2 was prepared.

[Example 1]
The polarizer body 1 was attached to a spin-coated vacuum chuck with the fine metal wire side facing up, and 2 mL of silicone resin 1 was dropped. Spin coating was performed under conditions of 500 rpm, 5 minutes, and then 1000 rpm for 10 minutes to form a coating film of silicone resin 1 on the surface of the polarizer body 1 on the side of the fine metal wires. The silicone resin 1 is cured by irradiating light of a high-pressure mercury lamp (frequency: 1.5 kHz to 2.0 kHz, main wavelength light: irradiation energy at 255 nm, 315 nm, 365 nm, 365 nm: 1000 mJ) for 1 minute, and a protective layer is formed on the surface. A wire grid type polarizer having the above was obtained. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 2]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 1 except that the polarizer body 2 was used instead of the polarizer body 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 3]
Dip coating is performed by dipping the polarizer body 1 in a bat filled with the silicone resin 2 with the metal fine wire side facing downward and at a speed of 0.5 m / min. The silicone resin is applied to the surface of the polarizer main body 1 on the metal fine wire side. Two coatings were formed. Heating was performed in a thermostatic bath at 100 ° C. for 1 hour to thermally cure the silicone resin 2 to obtain a wire grid type polarizer having a protective layer on the surface. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 4]
The polarizer body 1 was attached to a spin-coated vacuum chuck with the fine metal wire side facing up, and 2 mL of silicone resin 3 was dropped. Spin coating was performed under conditions of 500 rpm, 5 minutes, then 1000 rpm, 10 minutes, and a coating film of silicone resin 3 was formed on the surface of the polarizer main body 1 on the side of the fine metal wires. Heating was performed in a thermostatic bath at 100 ° C. for 1 hour to thermally cure the silicone resin 3 to obtain a wire grid polarizer having a protective layer on the surface. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 5]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 4 except that the polarizer body 2 was used instead of the polarizer body 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 6]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 4 except that the silicone resin 4 was used instead of the silicone resin 3. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 7]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 4 except that the silicone resin 5 was used instead of the silicone resin 3. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 8]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 7 except that the polarizer body 2 was used instead of the polarizer body 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 9]
A wire grid type polarizer having a protective layer on the surface was obtained in the same manner as in Example 3 except that the polarizer body 2 was used instead of the polarizer body 1 and the silicone resin 6 was used instead of the silicone resin 2. . Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 10]
To 200 mL of a mixed solvent of 70 mL of isopropyl alcohol and 30 mL of water, 0.1 mL of a silane coupling agent (manufactured by Shin-Etsu Silicone, KBM503) was added and mixed well to prepare a silane coupling agent solution.
The polarizer body 1 was attached to a spin-coated vacuum chuck with the fine metal wire side facing up, and 1 mL of the silane coupling agent solution was dropped. After spin coating was performed at 1000 rpm for 1 minute, then 3000 rpm for 5 minutes, treatment was performed in a thermostatic bath at 100 ° C. for 40 minutes to form a silane coupling agent layer on the surface of the polarizer body 1.
Thereafter, in the same manner as in Example 1, a wire grid polarizer having a protective layer on the surface was obtained. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 11]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 3 except that the epoxy resin 1 was used instead of the silicone resin 2. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 12]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 4 except that the epoxy resin 2 was used instead of the silicone resin 3. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 13]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 1 except that the acrylic resin 1 was used instead of the silicone resin 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 14]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 13 except that the polarizer body 2 was used instead of the polarizer body 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

[Example 15]
A wire grid polarizer having a protective layer on the surface was obtained in the same manner as in Example 13 except that the acrylic resin 2 was used instead of the acrylic resin 1. Table 2 shows the thickness of the protective layer, the average filling factor, and the change in optical characteristics.

  The wire grid polarizer of the present invention is useful as a polarizer for an image display device such as a liquid crystal display device, a rear projection television, or a front projector.

DESCRIPTION OF SYMBOLS 1 Wire grid type polarizer 2 Wire grid type polarizer 3 Wire grid type polarizer 4 Wire grid type polarizer 10 Light transmissive substrate 12 Metal thin wire 14 Groove 16 Polarizer body 18 Protective layer 20 Convex line 22 Concave line 24 Top part 26 First side 28 Second side

Claims (3)

A polarizer body in which a plurality of fine metal wires arranged in parallel to each other and a plurality of grooves along the fine metal wires are formed on a light-transmitting substrate, and a protective layer covering the surface of the polarizer body on the metal fine wire side A method of manufacturing a wire grid polarizer comprising:
The width of the groove is the same from the bottom of the groove to the opening, or gradually increases from the bottom of the groove to the opening,
A liquid curable composition having a surface tension at 25 ° C. of 28 mN / m or less is applied to the surface of the polarizer main body on the side of the fine metal wires, and the curable composition is cured to form the protective layer. A method of manufacturing a wire grid type polarizer. A polarizer body in which a plurality of fine metal wires arranged in parallel to each other and a plurality of grooves along the fine metal wires are formed on a light-transmitting substrate, and a protective layer covering the surface of the polarizer body on the metal fine wire side A method of manufacturing a wire grid polarizer comprising:
The width of the groove is the same from the bottom of the groove to the opening, or gradually increases from the bottom of the groove to the opening,
Applying a liquid curable composition having a viscosity at 25 ° C. of 5000 mPa · s or more to the surface of the polarizer main body on the side of the fine metal wires, and curing the curable composition to form the protective layer. A manufacturing method of a wire grid type polarizer characterized by. A wire grid polarizer obtained by the manufacturing method according to claim 1 or 2,
The wire grid type polarizer characterized in that an average filling rate of the protective layer into the groove defined below is 30% or less.
Average filling rate: Measure the height H1 from the bottom of the groove to the opening and the height H2 from the bottom of the groove to the protective layer, obtain the filling rate from the following formula (1), and calculate the filling rate in the five grooves. Averaged value.
Filling ratio = (H1-H2) / H1 × 100 (1).

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