JP2003322704A - Method of manufacturing reflection preventing sheet, reflection preventing sheet, optical element and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a reflection preventing sheet having no uneven interference in a reflection preventing layer and being excellent in appearance. <P>SOLUTION: The method of manufacturing the reflection preventing sheet B containing a step (1) to apply a coating liquid 3 to a surface x of a transparent resin layer of a sheet A with the transparent resin layer 2 having a projecting and recessing shape formed on the surface x wherein a material with a refractive index lower than that of the transparent resin layer 2 is contained in the coating liquid 3 and a step (2) to form the reflection preventing layer 3' by subjecting the coating liquid 3 to a hardening treatment, is characterized by subjecting the surface x of the transparent resin layer to a drying step (3) after subjecting the surface x to the coating step (1) and subsequently subjecting it to the hardening step (2). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing an antireflection sheet. Further, the present invention relates to an antireflection sheet obtained by the manufacturing method, an optical element and an image display device using the antireflection sheet. An optical element such as an antireflection polarizing plate using an antireflection film can be suitably used in various image display devices such as a liquid crystal display (LCD), an organic EL display device, a PDP and a CRT.

[0002]

2. Description of the Related Art A liquid crystal panel has been securing a firm position as a display by recent research and development. However, when the LCD is used for a car navigation monitor or a video camera monitor that is frequently used under bright illumination, the visibility is remarkably reduced due to surface reflection. Therefore, an antireflection sheet is laminated on the polarizing plate mounted on these devices. Also LCD
In such an image display device, the visibility of the image is hindered by the reflection on the surface of the display device. Therefore, as the antireflection sheet, an antireflection sheet having an uneven surface is used to impart antiglare properties.

Such an antireflection sheet can be obtained by applying a coating solution containing a low refractive index material on the surface of a transparent resin layer having an uneven surface and then curing the coating solution to form an antireflection layer. As the coating method of the coating liquid, various methods such as slot die, reverse gravure coating, and micro gravure are adopted. However, regardless of which coating method is used, resin flow in the coating liquid applied to the uneven surface of the transparent resin layer occurs before the coating liquid moves from the coating process to the curing process, resulting in a protrusion. There will be no resin remaining in the part. If the coating liquid is cured in that state, the thickness of the convex surface becomes thin with a diameter of several μm, and bright spots appear due to cissing on the uneven surface, and uneven interference due to the thickness difference of the antireflection layer occurs. . Therefore, it has conventionally been technically difficult to produce an antireflection layer that does not have a poor appearance due to uneven interference on the uneven surface.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an antireflection sheet by forming an antireflection layer with a coating liquid on the surface of the transparent resin layer of a sheet having a transparent resin layer having an uneven surface. It is an object of the present invention to provide a method for producing an antireflection sheet having good appearance without interference unevenness in the antireflection layer. Another object of the present invention is to provide an antireflection sheet obtained by the manufacturing method, an optical element provided with the antireflection sheet, and an image display device using the optical element.

[0005]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned object can be achieved by the following method for producing an antireflection sheet, and complete the present invention. Came to.

That is, the present invention provides a coating liquid containing a refractive index material having a refractive index lower than that of the transparent resin layer on the surface of the transparent resin layer of the sheet having the transparent resin layer having an irregular shape on the surface. (1) for coating the coating liquid and a step (2) for forming an antireflection layer by subjecting the coating liquid to a curing treatment
In the method for producing an antireflection sheet including the above, the step of applying the coating step (1), the step of drying (3), and the step of curing (2) are performed on the surface of the transparent resin layer. A manufacturing method of an antireflection sheet.

In the manufacturing method of the present invention, the drying step (3) is performed after the coating step (1). By the drying step (3), the vapor pressure is controlled to evaporate the solvent in the coating liquid on the surface to be coated before the coating liquid flows on the uneven surface of the transparent resin layer to cause the cissing phenomenon. I am letting you. Therefore, an antireflection layer is formed in which bright spots due to cissing are suppressed at convex portions on the uneven surface of the transparent resin layer and interference unevenness due to thickness difference is suppressed. As a result, it is possible to produce an antireflection sheet with significantly improved appearance defects.

It should be noted that a mechanism for suppressing cissing when a drying step (3) is provided between the coating step (1) and the curing step (2) (FIG. 1) and when it is not provided (FIG. 2) is shown in the drawings. Will be described with reference to. In FIG. 2 of the conventional example, the coating liquid 3 coated on the uneven surface x of the transparent resin layer 2 flows, causing cissing on the protrusions. When the curing step (2) is performed in this state, no resin remains on the convex portions of the antireflection layer 3'to be formed. On the other hand, in the example of FIG. 1 of the present invention, by the drying step (3), the surface vapor pressure of the coating liquid 3 applied to the uneven surface x of the transparent resin layer 2 changes, the solvent evaporates, and The state becomes like the tension 3a. By carrying out the curing step (2) in this state, a uniform layer is formed as the antireflection layer 3'to be formed.

In the method of manufacturing the antireflection sheet,
It is preferable that the drying step (3) is an air drying step of blowing air. The air drying step is preferably performed by blowing air at an angle of 10 ° to 90 ° with respect to the coating surface of the coating liquid containing the low refractive index material.

The drying step (3) is preferably carried out by an air-drying step in which air is blown, and the air is blown according to the inclination angle of the uneven surface of the transparent resin layer so that the vapor pressure on the surface of the liquid to be coated is increased. It tends to change and the solvent evaporates, resulting in skinning. In addition, this state is heat-cured in the curing step (2) and UV
A uniform antireflection layer is formed by curing by curing or the like.

In the method for producing the antireflection sheet,
The viscosity (25 ° C.) of the coating liquid containing the low refractive index material is preferably 1 to 5 mmPa · s. The production method of the present invention is particularly useful when the antireflection layer is formed using a low-concentration, low-viscosity coating liquid containing a large amount of solvent.

In the method of manufacturing the antireflection sheet,
It is preferable that the transparent resin layer is formed of an ultraviolet curable resin.

In the method for producing the antireflection sheet,
The antireflection layer preferably contains a siloxane skeleton.

In the method for producing the antireflection sheet,
It is preferable that the transparent resin layer has a refractive index of 1.49 to 1.72 and the antireflection layer has a refractive index of 1.30 to 1.48.

The present invention also relates to an antireflection sheet obtained by the above manufacturing method. The present invention also relates to an optical element in which the antireflection sheet is provided on one side or both sides of the optical element, and further to an image display device equipped with the antireflection sheet or the optical element.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing an antireflection sheet of the present invention will be described below with reference to the drawings (FIGS. 1 and 3).

FIG. 1 is a conceptual diagram showing each step of the method for producing an antireflection sheet of the present invention. In FIG. 1, a transparent resin layer 2 having an uneven surface x formed on one surface of a transparent substrate 1.
Step (1) of applying the coating liquid 3 containing a refractive index material having a lower refractive index than the transparent resin layer 2 to the transparent resin layer surface x using the sheet A having 2) is applied to the surface of the coating liquid 3 to cover the surface 3a, and then the hardening step (2) is applied to form the antireflection layer 3 ', whereby the antireflection sheet B is manufactured. It should be noted that FIG. 1 shows an example in which the uneven surface x of the transparent resin layer 2 is formed by the fine particles 4. The transparent resin layer 2 may appropriately contain fine particles for the light scattering effect and a functional filler for controlling the refractive index.

FIG. 3 is a conceptual diagram in which the air-drying step is performed by the blower 13 as the drying step (3). In FIG. 3, the continuously running sheet A is coated with the coating liquid 3 on the surface x of the transparent resin layer by the coating roll 11, and immediately after that, it is coated by the blower 13 with the coating liquid 3. The surface of the working liquid 3 is dried. Then, it is guided to the curing treatment tower 12. The blower 13 is equipped with air-drying equipment capable of controlling the vapor pressure on the coated surface according to the shape of the coated surface.

The sheet A illustrated in FIG. 1 has a transparent resin layer 2 on one surface of a transparent substrate 1 on which an uneven surface x is formed. As the sheet A, it is possible to use a sheet made of only the transparent resin layer 2.

Examples of the transparent substrate 1 include transparent polymers such as polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, acrylic polymers such as polymethylmethacrylate. A film consisting of In addition, polystyrene, styrene-based polymers such as acrylonitrile-styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, nylon, aromatic polyamides, etc. There is also a film made of a transparent polymer such as the amide polymer. Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers A film made of a transparent polymer such as a polymer, an epoxy-based polymer or a blend of the above-mentioned polymers can also be used. In particular, those having optical little birefringence are preferably used.

The thickness of the transparent substrate 1 can be appropriately determined, but is generally about 10 to 500 μm from the viewpoint of strength, workability such as handleability, and thin layer property. Especially 20-300μ
m is preferable, and 30 to 200 μm is more preferable.

The method for forming the transparent resin layer 2 on the transparent substrate 1 is not particularly limited, and an appropriate method can be adopted. For example, the surface of the film used for forming the transparent resin layer 2 may be roughened in advance by an appropriate method such as sandblasting, embossing roll, or chemical etching to give an uneven shape to the film surface. There is a method of forming the surface of the material itself for forming the resin layer 2 into an uneven shape. Further, there is a method in which a transparent resin layer is separately applied on the transparent resin layer 2 to give an uneven shape to the surface of the transparent resin layer by a transfer method using a mold or the like. Further, as shown in FIG. 1, there is a method in which fine particles 4 are dispersed and contained in the transparent resin layer 2 to give an uneven shape. These uneven shapes are formed by combining two or more methods.
You may form as a layer which combined the uneven | corrugated shaped surface of a different state. Among the methods of forming the transparent resin layer 2, the method of providing the transparent resin layer 2 containing the fine particles 4 dispersed therein is preferable from the viewpoint of formability of the uneven surface.

A method for providing the transparent resin layer 2 by dispersing and containing the fine particles 4 will be described below. The transparent resin layer 2
As the resin for forming the resin, fine particles 4 can be dispersed, and a resin having sufficient strength as a film after forming the transparent resin layer and having transparency can be used without particular limitation. Examples of the resin include a thermosetting resin, a thermoplastic resin, an ultraviolet curable resin, an electron beam curable resin, a two-component mixed resin, and the like. An ultraviolet curable resin that can efficiently form a light diffusion layer by a processing operation is suitable.

Examples of the ultraviolet curable resin include various resins such as polyester resins, acrylic resins, urethane resins, amide resins, silicone resins and epoxy resins, and include ultraviolet curing monomers, oligomers and polymers. The UV-curable resin preferably used is, for example, one having a UV-polymerizable functional group, and particularly one containing a component of an acrylic monomer or oligomer having two or more, particularly 3 to 6 of the functional group. . Among these, acrylic urethane type is preferable. Further, an ultraviolet polymerization initiator is blended with the ultraviolet curable resin.

The transparent resin layer 2 has a refractive index of 1.49 to 1.7.
It is preferable to adjust to 2. The refractive index of the transparent resin layer 2 is preferably higher than that of the transparent substrate 1, and the refractive index of the antireflection layer 3 is preferably lower than that of the transparent substrate 1. From the viewpoint of reflectance, the transparent resin layer 2 is required to have a high refractive index, and the antireflection layer 2 is required to have a lower refractive index. In order to obtain an antireflection film having a good antireflection effect and high display quality, the transparent resin layer 2 and the antireflection layer have the above-mentioned relations: the transparent resin layer 2> the transparent substrate 1> the antireflection layer 3. It is preferable that the refractive index difference becomes 3. The method for adjusting the refractive index of the transparent resin layer 2 is not particularly limited. The refractive index of the transparent resin layer can be adjusted by adding ultrafine particles of a metal or metal oxide having a high refractive index to the resin for forming the transparent resin layer. As the ultrafine particle material having a high refractive index, for example, Ti
O ₂ , ZnO, SnO ₂ , ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), ZrO ₂
Is preferably used. The average particle diameter of the ultrafine particles is preferably about 0.1 μm or less.

As the fine particles 4, inorganic or organic spherical or amorphous fillers having transparency such as various metal oxides, glass and plastics can be used without particular limitation. Examples of the inorganic or organic spherical or amorphous filler include crosslinked or uncrosslinked organic fine particles made of various polymers such as PMMA (polymethylmethacrylate), polyurethane, polystyrene, and melamine resin, glass, silica, alumina, and oxide. Inorganic particles such as calcium, titania, zirconium oxide, zinc oxide, tin oxide, indium oxide, cadmium oxide,
Examples thereof include conductive inorganic particles such as antimony oxide or composites thereof. The average particle size of the filler is preferably 0.5 to 10 μm, more preferably 1 to 5 μm. When the fine irregularities are formed by the fine particles, the amount of the fine particles used is preferably about 1 to 30 parts by weight with respect to 100 parts by weight of the resin.

The transparent resin layer 2 may contain additives such as a leveling agent, a thixotropic agent and an antistatic agent. When forming the transparent resin layer 2, a thixotropic agent (silica, mica or the like having a size of 0.1 μm or less)
By containing the, it is possible to easily form the uneven shape by the protruding particles.

The method for forming the transparent resin layer 2 is not particularly limited, and an appropriate method can be adopted. For example, the resin is applied, dried, and then cured. When the resin contains the filler or the like, the transparent resin layer 2 having an uneven shape on the surface is formed. The coating of the resin is
It is applied by an appropriate method such as fan ten, die coater, casting, spin coating, fan ten metalling, and gravure. Incidentally, upon coating, the resin is toluene, ethyl acetate, butyl acetate, methyl ethyl ketone,
It may be diluted with a general solvent such as methyl isobutyl ketone, isopropyl alcohol or ethyl alcohol, or may be applied as it is without being diluted. Also,
The thickness of the transparent resin layer 2 is not particularly limited, but is preferably 20 μm or less, about 0.5 to 20 μm, and particularly 1 to 10 μm.

An antireflection layer 3'is formed on the uneven surface of the transparent resin layer 2 with a coating liquid 3 containing a refractive index material having a refractive index lower than that of the transparent resin layer 2. It is preferable to adjust the refractive index of the antireflection layer to be 1.30 to 1.48.

The low refractive index material is not particularly limited as long as it has a refractive index lower than that of the transparent resin layer 2. As the low refractive index layer material, for example, a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in a resin, tetraethoxysilane,
Examples thereof include sol-gel materials using metal alkoxides such as titanium tetraethoxide. Further, as each material, a fluorine group-containing compound can be used in order to impart antifouling property to the surface. The antireflection layer preferably contains a siloxane skeleton from the viewpoint of scratch resistance, and as the low refractive index material, a sol-gel material is particularly preferable.

An example of the sol-gel material containing a fluorine group is perfluoroalkylalkoxysilane. Examples of the perfluoroalkylalkoxysilane include general formula (1): CF ₃ (CF ₂ ) _n CH
_{2 CH 2 Si (OR) 3} ( wherein, R represents the number 1-5 alkyl group having a carbon, n is an integer of 0 to 12) include compounds represented by. Specifically, for example, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltrisilane. Examples include ethoxysilane. Among these, n is 2 to 6
Compounds of are preferred. To form the low refractive index layer, silica, alumina, titania, zirconia, magnesium fluoride,
A sol in which ceria or the like is dispersed in an alcohol solvent may be added. In addition, additives such as metal salts and metal compounds can be appropriately blended.

The viscosity of the coating liquid 3 containing the low refractive index material is not particularly limited, but the viscosity (25 ° C.) is 1 to 5 mmPa.
・ It is preferable to adjust to s. Preferably 1-3 mmP
a · s. Usually, the solid content concentration of the coating liquid 3 is 0.1 to 10.
It is preferably 10% by weight, more preferably 0.5 to 5% by weight. The solvent used for the coating liquid 3 is not particularly limited,
For example, alcohol solvents such as ethanol and isopropyl alcohol; cellosolve solvents such as ethyl cellosolve and butyl cellosolve; diethyl oxalate, ethyl acetate,
Examples include ester solvents such as butyl acetate; ether solvents such as tetrahydrofuran. These solvents may be used alone or in combination of two or more.

In the method for producing an antireflection sheet of the present invention,
The antireflection layer is formed by sequentially applying the coating liquid 3 onto the surface of the transparent resin layer, the drying step (3), and the curing step (2).

The coating method of the coating liquid 3 in the coating step (1) is not particularly limited, and a usual method can be adopted. For example, a slot die method, a reverse gravure coating method, a micro gravure method, a dip method, a spin coating method, a brush coating method, a roll coating method, a flexographic printing method and the like can be mentioned.

The drying step (3) is not particularly limited as long as it is a method in which the surface of the liquid to be coated 3 is in a skinned state. As the drying step (3), for example, an air-drying means for blowing air with a blower as shown in FIG. 3 can be adopted. Other drying processes include hot air drying and radiant heat transfer. The air drying temperature (drying temperature) is usually about 20 to 50 ° C., preferably 23 to 30 ° C., and the air drying means can be carried out at room temperature. Air drying time is usually 1 to 15
Seconds, preferably 1.5 to 10 seconds. In the air-drying step, it is preferable that the air is blown at an angle of 10 ° to 90 ° with respect to the coated surface of the coating liquid 3. The angle may be either forward or backward in the traveling direction of the seat. Air volume is 1 to 15 m / s, preferably 2-1
It is 0 m / s. In addition, the drying step (3) is the coating liquid 3
It is preferable to carry out in a continuous step with the coating step (1) in order to quickly make the surface of the sheet skin. Further, it is preferable that the drying step (3) is continuously performed immediately after the coating step (1).

In the curing step (2), the antireflection layer 3'is formed by performing a curing treatment such as heat curing or UV curing depending on the kind of the low refractive index material used for preparing the coating liquid 3. . When the antireflection layer 3'has a siloxane structure, it is usually
A heat treatment is performed at about 60 to 150 ° C., and further at 70 to 120 ° C., so that the curing proceeds as the solvent volatilizes. The heat treatment time can be 100 hours or less, and further, a short time of 0.5 to 10 hours. The heat treatment means is not particularly limited, and for example, a method such as a hot plate, an oven, or a belt furnace is appropriately adopted.

The thickness of the antireflection layer 3'is not particularly limited, but is about 0.05 to 0.3 µm, particularly 0.1 to 0.3 µm.
It is preferably m. From the perspective of reducing reflectance,
It is preferable to set the value of thickness (nm) × refractive index to be about 140 nm.

An optical element can be bonded to the transparent substrate 1 of the antireflection sheet B shown in FIG. Examples of the optical element include a polarizer. The polarizer is not particularly limited, and various kinds can be used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film, and a dichroic dye such as iodine or a dichroic dye. Examples include polyene oriented films, such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydration products, polyvinyl chloride dehydrochlorination products, and the like. Among these, a polarizer made of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

A uniaxially stretched polarizer obtained by dyeing a polyvinyl alcohol film with iodine is produced, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length. You can If necessary, it may be immersed in an aqueous solution of boric acid, potassium iodide, or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to wash the stains and anti-blocking agents on the surface of the polyvinyl alcohol-based film, and by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as uneven dyeing is also obtained. is there. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. It can be stretched in an aqueous solution of boric acid or potassium iodide, or in a water bath.

The above-mentioned polarizer is usually used as a polarizing plate with a transparent protective film provided on one side or both sides. The transparent protective film is preferably one having excellent transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like. As the transparent protective film, the same material as the above-mentioned transparent substrate is used. As the transparent protective film, a transparent protective film made of the same polymer material on the front and back may be used, or a transparent protective film made of a different polymer material may be used. Those having excellent transparency, mechanical strength, thermal stability, moisture barrier property and the like are preferably used. Further, it is often preferable that the transparent protective film has less optical anisotropy such as retardation. Triacetyl cellulose is most suitable as the polymer forming the transparent protective film. When the antireflection sheet is provided on one side or both sides of a polarizer (polarizing plate), the transparent substrate of the antireflection sheet is
It can also serve as a transparent protective film for the polarizer. The thickness of the transparent protective film is not particularly limited, but is 10 to 300.
It is generally about μm.

When laminating the antireflection sheet on the polarizing plate, a transparent protective film, a polarizer and a transparent protective film may be sequentially laminated on the antireflection sheet, or a polarizer and a transparent protective film may be sequentially laminated on the antireflection sheet. It may be laminated on.

In addition, the surface of the transparent protective film to which the polarizer is not adhered may be a transparent resin layer or may have been treated for the purpose of preventing sticking. The hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film is a cured film made of an appropriate ultraviolet-curable resin such as acrylic or silicone that has excellent hardness and sliding characteristics. It can be formed by a method of adding to the surface of the. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer. The transparent resin layer, the sticking prevention layer and the like can be provided on the transparent protective film itself, or can be provided as an optical layer separately from the transparent protective film.

Between the layers of the polarizing plate, for example, a transparent resin layer,
A primer layer, an adhesive layer, a pressure-sensitive adhesive layer, an antistatic layer, a conductive layer, a gas barrier layer, a water vapor blocking layer, a water blocking layer, etc. may be inserted or laminated on the surface of the polarizing plate. Also. At the stage of forming each layer of the polarizing plate, the improvement may be carried out, if necessary, by adding or mixing conductive particles or antistatic agents, various fine particles, a plasticizer and the like to the material for forming each layer.

As an optical element, in practical use, an optical film in which another optical element (optical layer) is laminated on the polarizing plate can be used. Although the optical layer is not particularly limited, for example, a reflection plate, a semi-transmission plate, a retardation plate (1 /
One or two or more optical layers that may be used for forming a liquid crystal display device such as a viewing angle compensation film, etc. can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is further laminated on a polarizing plate, an elliptically polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on the plate, or a polarizing plate in which a brightness improving film is further laminated on the polarizing plate is preferable. An antireflection sheet is provided on the polarizing plate side of an elliptically polarizing plate, a polarizing plate with optical compensation, or the like.

If necessary, scratch resistance, durability,
Weather resistance, resistance to heat and humidity, heat resistance, moisture resistance, moisture permeability, antistatic properties, conductivity, improved adhesion between layers, improved mechanical strength, etc. Insertion, lamination, etc. can also be performed.

The reflective polarizing plate is a polarizing plate provided with a reflective layer, and is for forming a liquid crystal display device of the type that reflects incident light from the viewing side (display side) to display. Further, there is an advantage that it is possible to omit the incorporation of a light source such as a backlight and to easily reduce the thickness of the liquid crystal display device. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate through the transparent protective film or the like, if necessary.

Specific examples of the reflection type polarizing plate include a transparent protective film which is mat-treated if necessary, and a foil or vapor deposition film made of a reflective metal such as aluminum attached to one surface to form a reflective layer. can give.

The reflection plate may be used as a reflection sheet or the like in which a reflection layer is provided on an appropriate film conforming to the transparent film instead of the method of directly applying to the transparent protective film of the polarizing plate. Since the reflective layer is usually made of a metal, the use form in which the reflective surface is covered with a transparent protective film, a polarizing plate, or the like prevents the reduction of the reflectance due to oxidation, and thus the long-lasting initial reflectance. It is more preferable from the viewpoint of avoiding the additional provision of the protective layer.

The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror which reflects and transmits light by the reflective layer. The semi-transmissive polarizing plate is usually provided on the back side of the liquid crystal cell, and when the liquid crystal display device is used in a relatively bright atmosphere,
An image is displayed by reflecting incident light from the viewing side (display side), and in a relatively dark atmosphere, an image is displayed using a built-in light source such as a backlight built into the back side of the semi-transmissive polarizing plate. It is possible to form a liquid crystal display device of the type that displays That is, the semi-transmissive polarizing plate is useful for forming a liquid crystal display device of a type that can save energy for using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source in a relatively dark atmosphere. Is.

An elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on the polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called ¼ wavelength plate (also called a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also called a λ / 2 plate) is usually used to change the polarization direction of linearly polarized light.

The elliptically polarizing plate compensates (prevents) coloring (blue or yellow) caused by birefringence of the liquid crystal layer of a super twisted nematic (STN) type liquid crystal display device, and is used for black and white display without the coloring. Used effectively. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can also compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed obliquely. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has a function of preventing reflection. Specific examples of the retardation plate described above include polycarbonate, polyvinyl alcohol, polystyrene, polymethylmethacrylate, polypropylene and other polyolefins, polyarylate, and a birefringent film obtained by subjecting a film made of a suitable polymer such as polyamide to a stretching treatment. And a liquid crystal polymer oriented film, a liquid crystal polymer oriented layer supported by a film, and the like. The retardation plate may be one having an appropriate retardation according to the purpose of use, such as various wavelength plates or one for the purpose of compensating for the viewing angle and the like due to birefringence of the liquid crystal layer, and may be two or more kinds. It may be one in which retardation plates are laminated to control optical properties such as retardation.

The elliptically polarizing plate or the reflection type elliptically polarizing plate is a laminate of a polarizing plate or a reflection type polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can be formed by sequentially stacking them separately in the manufacturing process of a liquid crystal display device so as to form a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate is excellent in stability of quality, workability of lamination, and the like, and has an advantage that manufacturing efficiency of a liquid crystal display device can be improved.

The viewing angle compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than the direction perpendicular to the screen. Such a viewing angle compensating retardation plate includes, for example, a retardation film, an orientation film of a liquid crystal polymer or the like, or a transparent substrate on which an orientation layer of a liquid crystal polymer or the like is supported. The ordinary retardation film is a birefringent polymer film uniaxially stretched in the plane direction, whereas the retardation plate used as the viewing angle compensation film is biaxially stretched in the plane direction. A polymer film having birefringence, or a bidirectionally stretched film such as a polymer or a tilt-oriented film having a birefringence in which the refractive index in the thickness direction stretched uniaxially in the plane direction and also stretched in the thickness direction is controlled. Used. Examples of the tilted oriented film include those obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to stretching treatment and / or shrinking treatment under the action of the shrinkage force caused by heating, and those obtained by obliquely orienting a liquid crystal polymer. Can be mentioned. The raw material polymer of the retardation plate is the same as the polymer explained in the previous retardation plate, which prevents coloration due to the change of the viewing angle due to the phase difference due to the liquid crystal cell and enlarges the viewing angle for good viewing. An appropriate one can be used for the purpose such as.

From the viewpoint of achieving a wide viewing angle with good visibility, an optical anisotropic layer comprising an alignment layer of a liquid crystal polymer, particularly an inclined alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A compensation retardation plate can be preferably used.

The polarizing plate in which the polarizing plate and the brightness enhancement film are bonded together is usually used by being provided on the back side of the liquid crystal cell. The brightness enhancement film has a property of reflecting linearly polarized light of a predetermined polarization axis or circularly polarized light of a predetermined direction when natural light is incident due to reflection from a backlight of a liquid crystal display device or the back side, and transmits other light. A polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter and obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without being transmitted. It The light reflected by the surface of the brightness enhancement film is inverted through a reflection layer or the like provided on the rear side of the brightness enhancement film to be re-incident on the brightness enhancement film, and part or all of the light is transmitted as light in a predetermined polarization state to achieve brightness. The brightness can be improved by increasing the amount of light transmitted through the improvement film and by supplying polarized light that is difficult to be absorbed by the polarizer to increase the amount of light that can be used for liquid crystal display image display and the like. That is,
When light is input from the back side of the liquid crystal cell through a polarizer without using a brightness enhancement film, almost all light with a polarization direction that does not match the polarization axis of the polarizer is reflected by the polarizer. It is absorbed and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, about 50% of light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display and the like is reduced accordingly, and the image becomes dark. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and then inverted through a reflection layer or the like provided behind it. The light-increasing film transmits only the polarized light whose polarization direction is such that the light reflected and inverted between the two can pass through the polarizer. Since the light is supplied to the polarizer, light from a backlight or the like can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

A diffusion plate may be provided between the brightness enhancement film and the reflective layer or the like. The light in the polarization state reflected by the brightness enhancement film goes to the reflection layer and the like, but the installed diffusion plate uniformly diffuses the light passing therethrough, and at the same time, cancels the polarization state and becomes a non-polarization state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the light in the natural light state, is repeatedly directed to the reflection layer and the like, reflected through the reflection layer and the like, again passes through the diffuser plate, and is incident again on the brightness enhancement film. Thus, between the brightness enhancement film and the reflective layer, while maintaining the brightness of the display screen by providing a diffuser that returns the polarized light to the original natural light state, at the same time, reduce the unevenness of the brightness of the display screen, It is possible to provide a uniform and bright screen. It is considered that by providing such a diffusion plate, the number of repetitions of reflection of the first incident light is moderately increased, and it is possible to provide a uniform bright display screen in combination with the diffusion function of the diffusion plate.

The above-mentioned brightness enhancement film is, for example, a multilayer thin film of a dielectric or a multilayer laminate of thin films having different refractive index anisotropies, transmits linearly polarized light of a predetermined polarization axis and reflects other light. Those that exhibit the characteristics of, such as an oriented film of a cholesteric liquid crystal polymer or an oriented liquid crystal layer supported on a film substrate, reflect either left-handed or right-handed circularly polarized light and transmit other light. Appropriate materials such as those exhibiting characteristics can be used.

Therefore, in the brightness enhancement film of the type which transmits the linearly polarized light having the predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned to suppress the absorption loss by the polarizing plate. It can be efficiently transmitted. On the other hand, in the case of a type of brightness enhancement film that drops circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on the polarizer, but from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable that the light is incident on the polarizing plate. By using a ¼ wavelength plate as the retardation plate, circularly polarized light can be converted into linearly polarized light.

The retardation plate functioning as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer functioning as a quarter-wave plate and another phase difference for a light color light having a wavelength of 550 nm. It can be obtained by a method of superposing a retardation layer exhibiting characteristics, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one layer or two or more retardation layers.

Regarding the cholesteric liquid crystal layer,
Two layers or three layers with different reflection wavelengths
By arranging the layers so as to overlap each other, it is possible to obtain an element that reflects circularly polarized light in a wide wavelength range such as a visible light region, and based on that, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers, like the above-mentioned polarization separation type polarizing plate. Therefore, it may be a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above reflective polarizing plate or semi-transmissive polarizing plate is combined with a retardation plate.

Laminating an antireflection sheet on the optical element,
Further, various optical layers can be laminated on the polarizing plate by a method of sequentially laminating them separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that it is excellent in assembling work and can improve the manufacturing process of liquid crystal display devices and the like. Appropriate adhesion means such as an adhesive layer may be used for lamination. In adhering the above-mentioned polarizing plate and other optical films, the optical axes thereof can be set at an appropriate arrangement angle according to the intended retardation characteristics and the like.

At least one polarizing plate or at least one polarizing plate is used.
At least one surface of an optical element such as an optical film that is laminated in layers, the antireflection sheet is provided,
An adhesive layer for adhering to another member such as a liquid crystal cell may be provided on the surface on which the antireflection sheet is not provided. The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyamide, polyether, or a fluorine-based or rubber-based polymer as a base polymer is appropriately selected. Can be used. In particular, an acrylic pressure-sensitive adhesive, which has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesiveness, and has excellent weather resistance and heat resistance, can be preferably used.

In addition to the above, prevention of foaming phenomenon and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference, prevention of warpage of liquid crystal cells, and further formation of a liquid crystal display device of high quality and excellent durability, etc. From this point of view, an adhesive layer having a low moisture absorption rate and excellent heat resistance is preferable.

The adhesive layer is made of, for example, a natural or synthetic resin, particularly a tackifying resin, a filler made of glass fiber, glass beads, metal powder, other inorganic powder, or the like, a pigment, a coloring agent, an oxidizing agent. It may contain an additive such as an inhibitor that is added to the adhesive layer. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusion property.

The adhesive layer may be attached to an optical element such as a polarizing plate or an optical film by an appropriate method. As an example thereof, a pressure-sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a single solvent or a mixture of appropriate solvents such as toluene and ethyl acetate is prepared, A method in which it is directly attached on the optical element by an appropriate development method such as a casting method or a coating method, or a method in which an adhesive layer is formed on the separator and transferred to the optical element in accordance with the above, etc. can give. The adhesive layer may be provided as a layer in which layers having different compositions or types are stacked. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly 10 to 100 μm.
Is preferred.

The exposed surface of the adhesive layer is temporarily covered with a separator for the purpose of preventing contamination and the like until it is put into practical use. As a result, it is possible to prevent contact with the adhesive layer in the usual handling state. As a separator,
Except for the above thickness conditions, for example, a plastic film, a rubber sheet, a paper, a cloth, a non-woven fabric, a net, a foamed sheet or a metal foil, an appropriate thin sheet such as a laminate thereof, and a silicone-based or long-chain alkyl-based as necessary. It is possible to use an appropriate one according to the prior art, such as one coated with an appropriate release agent such as fluorine-based or molybdenum sulfide.

In the present invention, each layer such as the polarizer, the transparent protective film, the optical layer, etc. forming the above-mentioned optical element, and each layer such as the adhesive layer may be, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound. Alternatively, it may be one having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a cyanoacrylate compound or a nickel complex salt compound.

The optical element provided with the light diffusion sheet of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed in a conventional manner. That is, a liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell, an optical element, and a component such as an illumination system, if necessary, and incorporating a drive circuit. There is no particular limitation except that an element is used, and the method can be applied conventionally. The liquid crystal cell may be of any type such as TN type, STN type, and π type.

It is possible to form an appropriate liquid crystal display device such as a liquid crystal display device in which the above-mentioned optical element is arranged on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector in an illumination system. In that case, the optical element according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical elements are provided on both sides, they may be the same or different. further,
When forming a liquid crystal display device, appropriate components such as a diffusion plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight are formed in one layer or two layers at appropriate positions. The above can be arranged.

Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitting body (organic electroluminescent light emitting body). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminated body of such a light emitting layer and an electron injection layer formed of a perylene derivative, or a laminated body of these hole injection layer, light emitting layer, and electron injection layer is known. Has been.

In the organic EL display device, holes and electrons are injected into the organic light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and energy generated by the recombination of these holes and electrons is fluorescent. It emits light based on the principle that a substance is excited and the excited fluorescent substance emits light when returning to the ground state. The mechanism of recombination in the middle is similar to that of a general diode, and as can be expected from this, the current and the emission intensity show a strong nonlinearity with rectification with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to extract light emitted from the organic light emitting layer.
A transparent electrode formed of a transparent conductor such as O) is used as an anode. On the other hand, it is important to use a substance having a small work function for the cathode in order to facilitate electron injection and increase the luminous efficiency, and a metal electrode such as Mg-Ag or Al-Li is usually used.

In the organic EL display device having such a structure, the organic light emitting layer is formed of an extremely thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, when entering from the surface of the transparent substrate during non-light emission, the light transmitted through the transparent electrode and the organic light emitting layer and reflected by the metal electrode goes out to the surface side of the transparent substrate again, when viewed from the outside, The display surface of the organic EL display device looks like a mirror surface.

In an organic EL display device including an organic electroluminescent light-emitting body having a transparent electrode on the front surface side of an organic light-emitting layer that emits light when a voltage is applied and a metal electrode on the back surface side of the organic light-emitting layer, A polarizing plate can be provided on the surface side of the electrode, and a retardation plate can be provided between the transparent electrode and the polarizing plate.

Since the retardation plate and the polarizing plate have a function of polarizing the light that is incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized from the outside by the polarization action. Especially, the phase difference plate is 1/4.
The mirror surface of the metal electrode can be completely shielded by using a wave plate and adjusting the angle between the polarization directions of the polarizing plate and the retardation plate to π / 4.

That is, as for the external light incident on the organic EL display device, only the linearly polarized light component is transmitted by the polarizing plate. This linearly polarized light is generally elliptically polarized by the retardation plate, but it is circularly polarized when the retardation plate is a 1/4 wavelength plate and the polarization direction between the polarizing plate and the retardation plate is π / 4. .

This circularly polarized light passes through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, passes through the organic thin film, the transparent electrode, and the transparent substrate again, and becomes linearly polarized light again on the retardation plate. . Since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate. as a result,
The mirror surface of the metal electrode can be completely shielded.

[0079]

Examples Example 1 (Sheet A) Urethane acrylic UV curable resin (refractive index 1.53, Unideck manufactured by Dainippon Ink and Chemicals, Inc.)
An average particle size of 3.5 as fine particles per 100 parts by weight.
A coating solution obtained by mixing 14 parts by weight of polystyrene of 3.5 μm, 3.5 parts by weight of a benzophenone-based photopolymerization initiator, and a solvent (toluene) measured so that the solid content thereof is 40% by weight is applied to a coating solution of 80 μm in thickness. It was applied onto triacetyl cellulose, dried at 120 ° C. for 5 minutes, and then cured by irradiation with ultraviolet rays. In this way, a sheet A having a transparent resin layer with a thickness of about 5 μm, in which unevenness was formed on the surface, was obtained.

(Coating liquid 3) 1 part by weight of fluorine-containing polysiloxane resin (refractive index 1.39) and ethanol 99
A mixed solution (coating solution) containing parts by weight was used.

(Formation of Antireflection Layer) An antireflection sheet B was manufactured by using a coating apparatus which also has an air drying facility 13 as shown in FIG. Coating liquid 3 has a final thickness of 0.1μ
The sheet A was coated while adjusting the coating amount and the coating speed by the coating roll 11 so that the thickness would be m. Further, in the air-drying facility 13, the air volume at room temperature (25 ° C) is 1 m / s.
I sprayed with. Air drying was performed for 2 seconds. The wind was set so as to form an angle of 90 ° with respect to the surface to be coated. After air drying, heat treatment was performed at 100 ° C. to prepare an antireflection sheet B. About 200m from sheet A, anti-reflection sheet B
After producing, the state of the antireflection layer surface of the obtained antireflection sheet B was visually observed. As a result, it was confirmed that a good antireflection layer having no appearance defect due to the cissing phenomenon was obtained.

Comparative Example 1 In Example 1 (formation of antireflection layer), air-drying equipment 13 was used.
An antireflection sheet B was produced in the same manner as in Example 1 except that the above was not adopted. After preparing an antireflection sheet B of about 200 m from the sheet A, the state of the antireflection layer surface of the obtained antireflection sheet B was visually observed. As a result, the antireflection layer had a defective appearance of bright spots due to the cissing phenomenon.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing each step of an antireflection sheet of the present invention.

FIG. 2 is a conceptual diagram showing each step of a conventional antireflection sheet.

FIG. 3 is a conceptual diagram of a coating apparatus including an air drying process.

[Explanation of symbols]

1 transparent substrate 2 Transparent resin layer 3,3 'coating liquid (antireflection layer) 13 Air dryer B Anti-reflection sheet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 7/04 CFD G02B 5/02 C 4F006 G02B 5/02 5/30 4F100 5/30 G02F 1/1335 G02F 1/1335 C08L 101: 00 // C08L 101: 00 G02B 1/10 A (72) Inventor Takayuki Shigematsu 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H042 BA02 BA03 BA15 BA20 2H049 BA02 BA04 BA06 BA25 BA27 BB23 BB25 BB26 BB27 BB28 BB33 BB34 BB43 BB51 BB54 BB63 BB65 BB67 BC03 BC09 BC14 BC22 2H091 FA37X FB02 FC15 CC23 DD2525 CC23 BB23 BB23 BB23 BB23 BB23 BB23 AE03 BB04X BB06X BB24Y BB26Z BB57Y BB66X BB91Y BB91Z CB01 CB03 DA03 DA04 DB33 DB36 DB37 DB38 DB40 DB43 DB45 DB47 DB48 DB53 DB55 DC 24 EA12 EA21 EB16 EB22 EB24 EB33 EB38 EB39 EB43 EB52 4F006 AA02 AA12 AA16 AA22 AA32. JN01A JN06 JN06C JN08A JN18B JN30D YY00A

Claims (10)

[Claims] 1. A coating liquid containing a refractive index material having a refractive index lower than that of the transparent resin layer is applied to the surface of the transparent resin layer of a sheet having a transparent resin layer having an uneven shape on the surface. In the method for producing an antireflection sheet, including the step (1) of carrying out a curing treatment and the step (2) of forming an antireflection layer by curing the coating liquid, the coating step (1) is applied to the surface of the transparent resin layer. The method for producing an antireflection sheet, which comprises performing the drying step (3) and then the curing step (2) after the above step. 2. The method for producing an antireflection sheet according to claim 1, wherein the drying step (3) is an air drying step of blowing air. 3. The air drying step is performed by blowing air at an angle of 10 ° to 90 ° with respect to the coating surface of the coating liquid containing the low refractive index material. 1. The method for producing an antireflection sheet according to 1 or 2. 4. The antireflection sheet according to claim 1, wherein the coating liquid containing the low refractive index material has a viscosity (25 ° C.) of 1 to 5 mmPa · s. Production method. 5. The transparent resin layer is formed of an ultraviolet curable resin.
4. The method for producing an antireflection sheet according to any one of 4 above. 6. The method for producing an antireflection sheet according to claim 1, wherein the antireflection layer contains a siloxane skeleton. 7. The transparent resin layer has a refractive index of 1.49 to 1.7.
2. The method for producing an antireflection sheet according to claim 1, wherein the antireflection layer has a refractive index of 1.30 to 1.48. 8. An antireflection sheet obtained by the manufacturing method according to claim 1. 9. An optical element, wherein the antireflection sheet according to claim 8 is provided on one side or both sides of the optical element. 10. An image display device equipped with the antireflection sheet according to claim 8 or the optical element according to claim 9.