WO2022070883A1

WO2022070883A1 - Optical member

Info

Publication number: WO2022070883A1
Application number: PCT/JP2021/033696
Authority: WO
Inventors: 秀人橋口
Original assignee: フクビ化学工業株式会社
Priority date: 2020-09-29
Filing date: 2021-09-14
Publication date: 2022-04-07
Also published as: JP2022056210A

Abstract

Provided is a half mirror-like optical member, the optical member comprising a transparent substrate, a hard coating layer, and a half mirror layer in this order, wherein: the half mirror layer is layered so that nine or more layers of a high-refractive-index layer having a refractive index of 1.75-1.82 and a low-refractive-index layer having a refractive index of 1.28-1.36 are alternately layered and the high-refractive-index layer is the frontmost surface; the thickness of the high-refractive-index layer on the frontmost surface is 80-90 mm; the thicknesses of a first layer and a third layer from the hard coating layer of the half mirror layer are 120-440 nm; and a sharp and bright three-dimensional image can be synthesized on the surface of the optical member by using a display device mainly using polarized light.

Description

Optical member

The present invention relates to an optical member that functions as a half mirror. More specifically, the present invention relates to a half-mirror optical member arranged on the front surface of various displays and instrument panels of automobiles.

Conventionally, attempts have been made to inform the driver of various information by synthesizing a stereoscopic image on the front surface of the instrument panel of an automobile, that is, the surface of the instrument panel. Specifically, the speedometer and tachometer information behind (inside) the instrument panel can be seen through the instrument panel, and at the same time, the display device located above or below the front (driver side) of the instrument panel. The image and text information transmitted from the camera are reflected on the instrument panel to bring the reflected image into the field of view, and the driver is provided with information such as an image that looks three-dimensional (Patent Document 1).
As described above, the meter panel needs to be a member composed of a half mirror having two functions of translucency and reflectivity, which are contradictory to each other (Patent Document 2).
By the way, in recent years, most of the information such as images and characters for reflecting the reflected image from the outside and putting the reflected image in the field of view, including the speed inside the instrument panel and other information supporting the operation of the automobile, is displayed on the liquid crystal display. It has become like that. It has been found that when a stereoscopic image is synthesized via the half mirror using this liquid crystal display, the conventional half mirror has a problem of lacking brightness and sharpness of the image.

Jitsukaisho 62-115623 Gazette Japanese Unexamined Patent Publication No. 9-96702

In the process of diligently studying the characteristics of a liquid crystal display and a half mirror, the present inventors differ in the amount and ratio of polarization of the liquid crystal display depending on the mode of the liquid crystal used, that is, TN liquid crystal, VA liquid crystal, IPS liquid crystal, and the like. However, all of them are display devices mainly composed of polarized light. Therefore, they have found that a clear and bright stereoscopic image can be synthesized by focusing on the surface reflectance and light transmittance of the polarized light and developing a half mirror suitable for the surface reflectance, and have completed the present invention.

That is, according to the present invention, the optical member is provided with a transparent substrate, a hard coat layer, and a half mirror layer in this order.
In the half mirror layer, nine or more layers having a high refractive index having a refractive index of 1.75 to 1.82 and a low refractive index layer having a refractive index of 1.28 to 1.35 are alternately laminated to form a high refractive index. It is formed by laminating so that the rate layer is on the outermost surface, and the thickness of the high refractive index layer on the outermost surface is 80 to 90 nm.
The average reflectance of P-polarized light with an incident angle of 45 ° at a wavelength of 380 to 780 nm is 30% to 40%, the average reflectance of S-polarized light with an incident angle of 45 ° is 70% to 85%, and the incident angle is 45 °. The visual average reflectance of (P + S) / 2 polarization is 50% to 65%, and x: 0.30 to 0.32 and y: 0.32 to 0.34 in the XY chromaticity diagram. An optical member is provided.

The optical member of the present invention is
1) The thickness of the first layer and the third layer from the hard coat layer side of the half mirror layer is 120 to 440 nm.
2) Curing of the high refractive index layer containing 120 to 470 parts by mass of metal oxide particles and 8 to 10 parts by mass of a metal chelate compound with respect to 100 parts by mass of a binder component composed of an alkoxysilane compound or a hydrolyzate thereof. Being a cured product of the sex composition,
3) The low refractive index layer contains 65 to 330 parts by mass of hollow silica particles and 8 to 10 parts by mass of a metal chelate compound with respect to 100 parts by mass of a binder component composed of an alkoxysilane compound or a hydrolyzate thereof. Being a cured product of the composition,
4) A hard coat layer and an antireflection layer are included in this order on a surface opposite to the surface on which the half mirror layer of the optical member is formed, and the antireflection layer has a high refractive index from the hard coat layer side. It is provided with a layer and a low refractive index layer, and the visual average reflectance of P-polarized light having an incident angle of 45 ° at a wavelength of 380 to 780 nm is less than 0.5%, and the visual average reflectance of S-polarized light having an incident angle of 45 ° is 4. It has antireflection ability that the visual average reflectance of (P + S) / 2 polarization with less than 5.5% and an incident angle of 45 ° is less than 2.5%.
Is preferable.
Further, in the present invention, in the method for manufacturing the optical member, a cured body constituting each layer of a hard coat layer, a half mirror layer and an antireflection layer to be installed as needed is formed on a transparent substrate. Provided is a method for producing an optical member, which comprises applying a curable composition and then curing the composition to sequentially form the optical member by a so-called wet coating method.

Since the optical member of the present invention is excellent in half mirror performance against polarization, it reflects the information in addition to the transmitted image of the information of the image and characters transmitted from the display device using the polarization to be clear and bright. You can make a reflection image.
Since it has the above performance, it is possible to synthesize a clear stereoscopic image consisting of a transmitted image and a reflected image on an optical member and put it in the field of view. It can be suitably used as a front panel of an automobile instrument panel.

It is a reflectance distribution map with respect to the P polarized wave of the optical member obtained in Example 1. FIG. It is a reflectance distribution diagram with respect to the (P + S) / 2 polarized wave of the optical member obtained in Example 1. FIG. It is a schematic diagram which shows the typical layer structure of the optical member of this invention. It is a schematic diagram which shows the usage mode of the optical member of this invention.

<Optical member>
In the optical member of the present invention, a hard coat layer and a half mirror layer are formed as basic constituent layers on a transparent substrate.
In addition to these constituent layers, any layer can be provided as long as the various polarization reflection characteristics and color tone performance described later are not impaired. For example, an antifouling layer, an antistatic layer, an antibacterial / antiviral layer, or the like can be provided between the transparent substrate and the hard coat layer on the primer layer and the half mirror layer. In particular, it is a preferred embodiment to provide the antireflection layer on the surface opposite to the surface of the transparent substrate on which the half mirror layer is provided. Details will be described later.

<Transparent substrate>
In order for the optical member of the present invention to function as a half mirror, the base material needs to be a transparent base material.
The transparent substrate is preferably formed of a transparent resin having excellent impact strength and permeability. Specifically, a transparent resin having a total light transmittance of preferably 85% or more, more preferably 90% or more, still more preferably 92% or more at a wavelength of 380 to 780 nm is preferable.
The transparent base material used in the present invention is formed of at least one resin selected from the group consisting of acrylic resin, polycarbonate resin, polyethylene terephthalate resin and triacetyl cellulose resin from the viewpoint of transparency and impact resistance. Is preferable. A laminated transparent base material in which these resins are laminated may be used. For example, a laminated transparent base material of a polycarbonate resin and a polymethylmethacrylate resin may be used.
The thickness of the transparent substrate is appropriately selected and designed from the required translucency and impact resistance, but is usually in the range of 0.2 to 2.0 mm.

<Hard coat layer>
A hard coat layer is provided on the transparent substrate for the purpose of improving the adhesion between the substrate and the half mirror layer and the strength of the optical member.
Specifically, it is a layer having a thickness of 1 to 3 μm containing a resin component obtained by polymerizing and curing a (meth) acrylate-based polymerizable compound containing a urethane (meth) acrylate compound as a main component as a base material. If this thickness is too thin, it becomes difficult to secure the basic physical properties of the hard coat layer, for example, hardness and strength. If it is excessively thick, the difference in physical properties from the transparent base material, for example, the difference in flexibility and elongation becomes large, and molding defects such as cracks are likely to occur. The thickness of the hardcoat layer is preferably 1.2 to 2.5 μm, more preferably 1.5 to 2 μm.
The hard coat layer is a resin component obtained by polymerizing and curing a (meth) acrylate-based polymerizable compound, specifically a mixture of a urethane (meth) acrylate compound and a normal (meth) acrylate compound, and a silane coupling. It is preferred to contain agents, silica particles and metal chelate compounds.

[Resin component]
The resin component has a function as a binder for forming the hard coat layer and serves as a base material. The resin component is a polymer of the (meth) acrylate-based polymerizable compound shown below.
As the (meth) acrylate-based polymerizable compound, a mixture of a tetrafunctional or higher functional urethane (meth) acrylate compound and a normal (meth) acrylate compound is preferably used.
A urethane (meth) acrylate compound having four or more functionalities forms a relatively hard portion by curing, and a (meth) acrylate compound forms a flexible portion by curing. It is possible to form a film having both hardness.
The urethane (meth) acrylate compound is obtained by further reacting a terminal isocyanate compound obtained by reacting a polyhydric isocyanate compound with a polyol compound having a plurality of hydroxyl groups with a hydroxyl group-containing (meth) acrylate. The (meth) acryloyl group in the urethane (meth) acrylate compound is a functional group, and for example, a urethane (meth) acrylate compound having four (meth) acryloyl groups is tetrafunctional.

Therefore, the tetrafunctional or higher functional urethane (meth) acrylate compound is a urethane compound having four or more (meth) acryloyl groups, and for example, pentaerythritol di (meth) acrylate is reacted with the terminal isocyanate compound. , A compound in which two (meth) acryloyl groups are introduced at both ends of the isocyanate compound is used as a tetrafunctional urethane (meth) acrylate compound.
As the hexafunctional urethane (meth) acrylate compound, pentaerythritol tri (meth) acrylate is reacted with both-terminal isocyanates (for example, trihexadiethylenediisocyanate) to cause three (meth) acryloyl at each end of the molecular chain. A compound having a group is obtained.

In addition to the tetrafunctional or higher functional urethane (meth) acrylate compound, it is preferable to add the (meth) acrylate compound for the purpose of improving the crack resistance, flexibility and elongation of the hard coat layer.
Specific (meth) acrylate compounds include monofunctional (meth) acrylate compounds such as methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate; 1,4 butanediol di (meth) acrylate, Bifunctional (meth) acrylate compounds such as ethylene glycol di (meth) acrylate and diethylene glycol di (meth) acrylate; pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, Examples thereof include 3 to 4 functional (meth) acrylate compounds such as trimethylolpropantri (meth) acrylate; and 5 to 6 functional (meth) acrylate compounds such as dipentaerythritol penta (meth) acrylate and dipentaerythritol hexaacrylate. In particular, a 1- to trifunctional (meth) acrylate compound is suitable because it has excellent crack resistance.

In the present invention, the above-mentioned tetrafunctional or higher functional urethane (meth) acrylate compound and the (meth) acrylate compound are usually blended in a mass ratio of 30/70 to 50/50 [(meth) acrylate / urethane (meth) acrylate]. It is preferable that it is. If the amount of the (meth) acrylate compound used is too large, the hardness of the obtained hardcoat layer becomes small, the wear resistance is lowered, and the function as the hardcoat layer is lowered.

In the hard coat layer, in addition to the above-mentioned tetrafunctional or higher functional urethane (meth) acrylate compound and (meth) acrylate compound, a trifunctional or lower functional urethane (meth) acrylate compound is used to improve the flexibility of the hard coat layer. Further may be used.

〔Silane coupling agent〕
The hardcoat layer preferably contains a silane coupling agent. The silane coupling agent is used to stably disperse and hold the silica particles described later in the hard coat layer without falling off, and at the same time, to secure the adhesion with the half mirror layer formed on the silica particles. It is a component.

As the silane coupling agent, conventionally known ones can be used without any limitation.
Specifically, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, γ- (meth) acryloxipropyltrimethoxysilane, γ-glycidoxy Propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, N- ( β-Aminoethyl) -γ-aminopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ- (N-styrylmethyl-β-aminoethylamino) propyltrimethoxysilane hydrochloride, γ-chloropropyltrimethoxy Examples thereof include silane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane and the like.
In such a silane coupling agent, the hydrolyzate is polycondensed at the same time as the hydrolysis to form a polymer connected in a network shape by a Si—O—Si bond. Therefore, by using such a silane coupling agent, the hard coat layer can be made dense.

In the present invention, the content ratio of the silane coupling agent in the hard coat layer is preferably 1 to 30 parts by mass, more preferably 1 to 30 parts by mass, based on 100 parts by mass of the resin component formed from the above-mentioned (meth) acrylate-based polymerizable compound. It is set in the range of 10 to 20 parts by mass. If the content of the silane coupling agent is higher than necessary, the basic performance of the hardcoat layer, that is, hardness and scratch resistance, will be impaired. If this content is too small, the adhesion to the half mirror layer is impaired and peeling or the like is likely to occur.

[Solid silica particles]
The hardcourt layer preferably contains solid silica particles. Solid silica particles are non-hollow particles that are dense inside and do not have cavities inside, and have a density of usually 1.9 g / cm ³ or more. The solid silica particles preferably have a particle size of 5 to 500 nm and a refractive index in the range of 1.44 to 1.5. By containing the solid silica particles, basic properties such as hardness can be uniformly imparted over the entire hard coat layer. Further, by including such solid silica particles, the adhesion to the half mirror layer containing the silica particles or the metal oxide particles described later is enhanced, and the hard coat layer and the half mirror layer are effectively prevented from cracking. can do.
The content of the solid silica particles is preferably 10 to 80 parts by mass, more preferably 30 to 60 parts by mass, per 100 parts by mass of the resin component formed from the above-mentioned (meth) acrylate-based polymerizable compound. By including such solid silica particles in the hard coat layer in such a range, the basic characteristics of the hard coat layer are maintained, the adhesion to the half mirror layer is enhanced, and cracking and the like are effectively prevented. Can be prevented.

[Metal chelate compound]
The hardcoat layer preferably contains a metal chelate compound. The metal chelate compound is used for the purpose of introducing a crosslinked structure into the hardcoat layer to increase the denseness and strength of the hardcoat layer, as well as the hardness.
A crosslinked structure is also formed in the resin component made of the (meth) acrylate-based polymerizable compound described above, but its denseness is not sufficient because flexibility is also required. Metal chelate compounds are used to compensate for the reduced tightness of the hardcourt layer without compromising its flexibility, in other words to adjust mechanical properties such as hardness that are affected by the tightness of the film. It is a thing. Further, since such a metal chelate compound is also contained in the half mirror layer, the use of the metal chelate compound increases the affinity between the hard coat layer and the half mirror layer, further enhances the adhesion, and molds. It is possible to effectively prevent time cracking and the like.

As such a metal chelate compound, a compound of titanium, zirconium, aluminum, tin, niobium, tantalum or lead containing a bidentate ligand is suitable.
A bidentate ligand is a chelating agent having 2 coordination loci, that is, 2 atoms that can be coordinated to a metal, and generally has a 5- to 7-membered ring depending on O, N, and S atoms. Form to form a chelate compound.

Typical metal chelate compounds include triethoxy mono (acetylacetonet) titanium, tri-n-propoxymono (acetylacetonate) titanium, diethoxybis (acetylacetonate) titanium, and monoethoxytris (acetylacetone). Nart) Titanium, Tetrakiss (Acetylacetone) Titanium, Triethoxy Mono (Ethylacetone Acetate) Titanium, Diethoxy Bis (Ethylacetone Acetate) Titanium, Monoethoxy Tris (Ethylacetone Acetate) Titanium, Mono (Acetylacetone Acetate) Tris Titanium chelate compounds such as (ethylacetate) titanium, bis (acetylacetonate) bis (ethylacetoneacetate) titanium, tris (acetylacetonet) mono (ethylacetoneacetate) titanium;
Triethoxy mono (acetylacetonate) zirconium, tri-n-propoxymono (acetylacetonate) zirconium, diethoxybis (acetylacetonate) zirconium, monoethoxytris (acetylacetonate) zirconium, tetrakis (acetylacetonate) ) Zirconium, Triethoxy mono (ethylacetate) zirconium, diethoxybis (ethylacetacetate) zirconium, monoethoxytris (ethylacetacetate) zirconium, tetrakis (ethylacetacetate) zirconium, mono (acetylacetonate) tris ( Zirconium chelating compounds such as (ethylacetate acetate) zirconium, bis (acetylacetonate) bis (ethylacetacetate) zirconium, tris (acetylacetonate) mono (ethylacetoacetate) zirconium;
Diethoxy mono (acetylacetonate) aluminum, monoethoxybis (acetylacetonate) aluminum, di-i-propoxymono (acetylacetonate) aluminum, mono-i-propoxybis (ethylacetoacetate) aluminum, mono Examples thereof include aluminum chelate compounds such as ethoxy bis (ethyl acetoacetate) aluminum, diethoxy mono (ethyl acetoacetate) aluminum, tris (acetylacetonate) aluminum, and bis (ethylacetate acetate) mono (acetylacetonate) aluminum.

The above-mentioned metal chelate compound is used in an amount of preferably 0.1 to 30 parts by mass, more preferably 0.5 to 15 parts by mass, per 100 parts by mass of the resin component formed from the (meth) acrylate-based polymerizable compound. Will be done. By using the metal chelate compound within this range, the adhesion between the metal chelate compound and the half mirror layer formed on the hard coat layer can be improved.

A particularly suitable hard coat layer is a silane coupling agent or a silane coupling agent thereof with respect to 100 parts by mass of a resin component obtained by curing a tetrafunctional or higher functional urethane (meth) acrylate compound and a 1 to trifunctional (meth) acrylate compound. 1 to 30 parts by mass of the hydrolyzate, 10 to 80 parts by mass of solid silica particles having a particle size of 5 to 500 nm and a refractive index in the range of 1.44 to 1.50, and 0.1 to 30 parts by mass of the metal chelate compound. Formed from parts.

[Formation of hard coat layer]
In the hard coat layer, a specific amount of each of the above components and an optional component such as a photopolymerization initiator are dissolved in the following solvent for the purpose of viscosity adjustment and easy coating to obtain a coating solution for forming a hard coat layer. The solution is applied onto a transparent substrate to form a coat film, and then the coat film is dried as necessary and then irradiated with ionizing radiation such as ultraviolet rays and electron beams to form the (meth) acrylate. It is formed by curing a system-polymerizable compound or an oligomer thereof.
When the coating solution for forming the hard coat layer is cured by ultraviolet rays, it is preferable to add a photopolymerization initiator to the coating solution. The photopolymerization initiator may be any one that generates radicals when irradiated with ultraviolet rays, and is known, for example, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones and the like. Photopolymerization initiator can be used. The amount of the photopolymerization initiator added is preferably 1 to 10 parts by mass, more preferably 1 to 7 parts by mass with respect to 100 parts by mass of the urethane acrylate used.
Solvents used in the coating solution are alcohol compounds such as methyl alcohol, ethyl alcohol and propyl alcohol; aromatic compounds such as toluene and xylene; ester compounds such as ethyl acetate, butyl acetate and isobutyl acetate; acetone and methyl ethyl ketone (MEK). , Methylisobutylketone (MIBK), ketone compounds such as diacetone alcohol, and the like are suitable. In addition, solvents such as methylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and cellosolve compounds such as methyl cellosolve, ethyl cellosolve, and propylene glycol monomethyl ether can also be used.
Each of the components constituting the coating solution for forming a hard coat layer is usually mixed and stirred arbitrarily at around room temperature to obtain a solution. When a commercially available solid silica particle dispersion (sol) is used, a solvent as a dispersion medium is inevitably mixed in the solution. The solvent in the coating solution and the separately blended solvent are removed in the drying and curing steps.
The method of applying the solution to the transparent substrate is not particularly limited, and methods such as a dip coating method, a roll coating method, a die coating method, a flow coating method, and a spray method are adopted, but from the viewpoint of appearance quality and film thickness control. Therefore, the dip coat method is suitable.

<Half mirror layer: HM layer>
A half mirror layer is formed on the formed hard coat layer. In the present invention, the layer structure of the half mirror layer is characteristic.
By adopting the following layer structure peculiar to the present invention, the visual average reflectance of P-polarized light having an incident angle of 45 ° at a wavelength of 380 to 780 nm is 20% or more, and the visual average reflectance of S-polarized light having an incident angle of 45 ° is 20% or more. It has a polarization reflection characteristic that the visual average reflectance of (P + S) / 2 polarization with an incident angle of 45 ° or more is 35% or more, and x: 0.30 to 0.32, y in the XY chromaticity diagram. : The optical characteristic of 0.32 to 0.34 is exhibited.

In the half mirror layer of the present invention, a high refractive index layer having a refractive index of 1.75 to 1.82 and a low refractive index layer having a refractive index of 1.28 to 1.35 are alternately laminated, and each layer is formed. It has a feature that the total number of layers is 9 or more and the outermost surface is a high refractive index layer.
When each of the refractive indexes of the high refractive index layer and the low refractive index layer does not satisfy the above range, the transmission image or the reflection image is poorly reflected and the performance as a half mirror is inferior to that satisfying the above range.
It is essential that the total number of layers constituting the half mirror layer is 9 or more in order to exhibit excellent polarization reflection characteristics. The upper limit is 17 layers from the viewpoint of the labor and cost of forming each layer and the saturation of the improvement of the polarization reflection characteristics. When the total number of layers is 8 or less, the numerical value of the polarization reflection characteristic is not satisfied and the mirror performance for the polarized wave is inferior.
The outermost surface of the half mirror layer needs to be a high refractive index layer having a refractive index of 1.75 to 1.82. When the outermost surface has a low refractive index layer having a refractive index of 1.28 to 1.35, sufficient mirror performance is not exhibited and the mirror does not function as a half mirror.
When the total number of layers of each layer is an odd number of 9 or more, the outermost surface is a high refractive index layer, so that the lowest layer (the layer in contact with the hard coat layer) is the high refractive index layer. In the case of an even number of 9 layers or more, the lowest layer is a low refractive index layer. In order to exhibit better mirror performance, a layer structure in which the total number of layers is an odd number, that is, the lowest layer is a high refractive index layer is preferable.
The thickness of each of the high refractive index layer and the low refractive index layer is usually selected from the range of 70 to 440 nm, preferably 80 to 180 nm. In particular, the thickness of the outermost high-refractive index layer is 80 to 90 nm, and the thickness of the first and third layers from the hard coat layer of the half mirror layer is 120 to 440 nm, preferably 150 to 180 nm. When designed to be there, it is an optical member with excellent half-mirror performance.

By adopting the above-mentioned unique layer structure, the visual average reflectance of P-polarized light having an incident angle of 45 ° at a wavelength of 380 to 780 nm is 30% to 40%, and the visual average reflectance of S-polarized light having an incident angle of 45 ° is 70%. It has a polarization reflection characteristic in which the visual average reflectance of (P + S) / 2 polarization with an incident angle of 45 ° is 50% to 65%, and x: 0.30 to 0.32 in the XY chromaticity diagram. , Y: The optical characteristic of 0.32 to 0.34 is exhibited.
The polarized wave has an average reflectance of 20% or more for P polarization, an average reflectance of 50% or more for S polarization, and an average reflectance of 35% or more for (P + S) / 2 polarization. It has excellent reflectance to light, and the reflected image formed by reflecting characters and images made of polarized light can be clearly seen.
Further, since x: 0.30 to 0.32 and y: 0.32 to 0.34 in the XY chromaticity diagram, the optical member has substantially low saturation (colorless and transparent), and the reflected image. Coloring does not occur in the transmitted image, and the original colors such as characters and images created through the polarizing plate are reflected in the same color tone and can be visually recognized.

In the present invention, the P-polarized visual sensation average reflectance, the S-polarized visual sensation average reflectance, and the (P + S) / 2-polarized visual sensation average reflectance are the following methods. It is a physical property value measured by.
P-polarized visual average reflectance:
Using a "V-650" testing machine manufactured by JASCO Corporation, the reflectance is measured every 10 nm at a scanning speed of 1000 nm / min. The light used for the measurement is light having a wavelength of 380 to 780 nm, which is obtained by removing the vertical component through a polarizing element to obtain only parallel polarization. This reflectance was multiplied by the weighting factor described in JIS Z 8722 and integrated, and divided by the integrated value of the weighting factor to obtain the visual average reflectance. The larger this value is, the better the reflection performance is.
S-polarized visual average reflectance:
The light is measured with only vertical polarization after removing the parallel direction component through the polarizing element. Except for the direction in which the polarizing element was installed, the measurement was performed in the same manner as in the measurement of the visual average reflectance of the P-polarized light.
(P + S) / 2 polarized visual average reflectance:
The splitter is installed at 45 degrees, and the light is measured with half the amount of the vertical component and half the amount of the parallel component. It was measured and calculated in the same manner as the visual average reflectance of the P-polarized light except for the direction in which the splitter was installed.
X and y values in the XY chromaticity diagram:
The reflectance of each of the above-mentioned polarizations was measured using a "V-650" tester manufactured by JASCO Corporation, and the reflectance was calculated from the weighting factor shown in Table 4 of JIS Z 8722 to the tristimulus value in the XYZ display system. X, Y, Z) was calculated and converted into x = X / (X + Y + Z) and y = Y / (X + Y + Z) to calculate the chromaticity coordinates (x, y).
When the x value is in the range of 0.30 to 0.32 and the y value is in the range of 0.32 to 0.34, it means that the chromaticity is close to colorless and transparent.

<Low refractive index layer>
The refractive index of the low refractive index layer is 1.28 to 1.35. The low refractive index layer is laminated on the hard coat layer or on the high refractive index layer to form a multilayer structure in which the high refractive index layer is alternately laminated.
The low refractive index layer is preferably a cured product of a curable composition containing an alkoxysilane compound or a hydrolyzate thereof, silica particles and a metal chelate compound.

[Alkoxysilane compound]
The alkoxysilane compound or its hydrolyzate is polycondensed at the same time as hydrolysis to form a crosslinked body connected in a network by Si—O—Si bond, and becomes a base material of a low refractive index layer. By using an alkoxysilane compound or a hydrolyzate thereof, the low refractive index layer can be made dense.
As described above, the alkoxysilane compound is not limited as long as it is a silane compound capable of polycondensation at the same time as hydrolysis, and is not limited to tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, and vinyltrimethoxy. Silane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ- (meth) acryloxipropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) Examples thereof include alkoxysilane compounds such as ethyltrimethoxysilane.
Depending on the type of the alkoxysilane compound, it is preferable to prepare a decomposition product which has been partially hydrolyzed in advance with a dilute acid or the like for the purpose of improving the solubility in water or a solvent. The method of pre-hydrolyzing is not particularly limited, and a method of hydrolyzing a part thereof using an acid catalyst such as acetic acid, or a method of adding an alkoxysilane compound in a coating solution for forming a low refractive index layer together with other components. A method in which an acid coexists and is partially hydrolyzed is adopted.
From the viewpoint of preventing coloring of the optical member and ensuring transparency, an alkoxysilane compound represented by the following general formula or a hydrolyzate thereof is suitable.

(In the formula, R is an alkylene group having 1 to 3 carbon atoms, R ¹ is a methyl group or an ethyl group, and a is 0 or 1).
Typical examples of the alkoxysilane compound of the general formula (1) include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldiethoxysilane.

[Silica particles]
Silica particles are used to control the refractive index of the low index of refraction layer within a predetermined range. Hollow silica and solid silica exist as silica particles. It is preferable to use hollow silica particles in order for the low refractive index layer to exhibit a relatively low refractive index.
Hollow silica is silica having a cavity inside, and a preferable average particle size is 10 to 150 nm. Since the hollow silica particles are hollow particles, their density is lower than that of other silica particles, and is usually 1.5 g / cm ³ or less.
Such hollow silica particles are known in their own right, and are manufactured and commercially available, for example, by synthesizing silica in the presence of a template and a surfactant and finally firing to decompose and remove the surfactant. There is. In such a commercially available product, since the hollow silica particles are dispersed in a solvent such as water or alcohol and provided as a so-called sol, the low refractive index layer is prepared to form the low refractive index layer. These solvents are inevitably mixed in the forming coating solution. However, in the drying and curing process after coating, these solvents are volatilized and removed together with the solvent separately added to prepare the coating solution.
If the index of refraction of the low index layer is designed to be relatively high, solid silica is used. As the solid silica, the solid silica described in the section of the hard coat layer is used without limitation.
The content of silica particles in the coating solution for forming a low refractive index layer depends on the set refractive index of the low refractive index layer and the amount of other contained components, but is preferably 60 with respect to 100 parts by mass of the alkoxysilane compound. It is up to 400 parts by mass, more preferably 65 to 330 parts by mass.

[Metal chelate compound]
It is preferable to contain a metal chelate compound for the purpose of increasing the density and strength of the low refractive index layer and further increasing the hardness. As the metal chelate compound, the metal chelate compound described in the section of the hard coat layer can be used as it is without limitation.
The content of the metal chelate compound in the coating solution for forming a low refractive index layer is preferably 5 to 15 parts by mass, more preferably 6 to 12 parts by mass, and more preferably 8 to 8 parts by mass with respect to 100 parts by mass of the alkoxysilane compound. It is 10 parts by mass.

[Formation of low refractive index layer]
The low refractive index layer is laminated on the hard coat layer or the high refractive index layer, and a half mirror layer having a multi-layer structure alternately laminated with the high refractive index layer is formed.
In the low refractive index layer, each of the above components is dissolved in a specific amount, and further, any component is dissolved in a solvent for the purpose of viscosity adjustment and easy coating to prepare a coating solution for forming a low refractive index layer, and after this solution is applied. It can be formed by drying, then heating and heat curing.
As the solvent used for the coating solution for forming a low refractive index layer, the solvent described in the section of the coating solution for forming a hard coat layer is used without limitation. Similarly, the same coating method is adopted, but the dip coating method is preferable from the viewpoint of appearance quality and film thickness control.

<High refractive index layer>
The refractive index of the high refractive index layer is 1.75 to 1.82. The high refractive index layer is laminated on the hard coat layer or on the low refractive index layer to form a multilayer structure in which the low refractive index layer is alternately laminated.
The high refractive index layer is preferably a cured product of a curable composition containing an alkoxysilane compound, a metal oxide particle and a metal chelate compound.

[Alkoxysilane compound]
The alkoxysilane compound or its hydrolyzate can make the high refractive index layer dense as well as the low refractive index layer.
As the alkoxysilane compound, the compounds listed in the section of the low refractive index layer can be used without limitation. Also in the high refractive index layer, the alkoxysilane compound represented by the general formula (1) is suitable for the same reason.

[Metal oxide particles]
It is preferable to use metal oxide particles in order to control the refractive index of the high refractive index layer within a predetermined range.
Specific metal oxide particles include zirconium oxide particles (refractive index = 2.40), and composite zirconium metal in which zirconium oxide and other oxides such as silicon oxide are composited at the molecular level to adjust the refractive index. Oxide particles, titanium oxide particles (refractive index = 2.71), composite titanium metal oxide particles whose refractive index is adjusted by combining titanium oxide with other oxides such as silicon oxide and zirconium oxide at the molecular level. Etc. are used. These metal oxide particles are appropriately combined to prepare a layer having a desired refractive index. Such particles are known in their own right and are commercially available.
The average particle size of the metal oxide particles is preferably 1 to 100 nm, more preferably 1 to 70 nm. The refractive index of the metal oxide particles is preferably 1.70 to 2.80, more preferably 1.90 to 2.50.
The content of the metal oxide particles in the coating solution for forming the high refractive index layer depends on the set refractive index of the high refractive index layer and the amount of other contained components, but is preferably based on 100 parts by mass of the binder component. It is 100 to 500 parts by mass, more preferably 120 to 470 parts by mass.

[Metal chelate compound]
It is preferable to contain a metal chelate compound for the purpose of increasing the density and strength of the high refractive index layer and further increasing the hardness. As the metal chelate compound, the metal chelate compound mentioned in the section of the hard coat layer can be used without limitation.
The content of the metal chelate compound in the coating solution for forming a high refractive index layer is preferably 5 to 15 parts by mass, more preferably 6 to 12 parts by mass, and further preferably 8 to 8 parts by mass with respect to 100 parts by mass of the alkoxysilane compound. It is 10 parts by mass.

[Formation of high refractive index layer]
The high refractive index layer is laminated on the hard coat layer or the low refractive index layer, and a half mirror layer having a multi-layered structure alternately laminated with the low refractive index layer is formed. As described above, the outermost surface of the half mirror layer needs to be a high refractive index layer.
In the high-refractive index layer, a specific amount of each of the above components and an optional component are dissolved in a solvent for the purpose of viscosity adjustment and easy coating to prepare a coating solution for forming a high-refractive index layer, and then this solution is applied. It can be formed by drying, then heating and heat curing.
As the solvent used for the coating solution for forming a high refractive index layer, the solvent described in the section of the coating solution for forming a hard coat layer is used without limitation. Similarly, the same coating method is adopted, but the dip coating method is preferable from the viewpoint of appearance quality and film thickness control.

<Anti-reflection layer: AR layer>
The optical member in which the hard coat layer and the antireflection layer are laminated in this order on the surface of the transparent substrate opposite to the surface on which the half mirror layer is provided (hereinafter, also referred to as the back surface) is the thickness of the transparent substrate and the incidental light. This is a preferred embodiment because the double image caused by the angle, that is, the reflection on the front surface and the reflection on the back surface of the half mirror layer can be reduced as much as possible.
The antireflection layer is a layer provided with a high refractive index layer and a low refractive index layer in order on the hard coat layer, and as a result, the visual average reflectance of P-polarized light having an incident angle of 45 ° at a wavelength of 380 to 780 nm is obtained. Less than 0.5%, the average visual reflectance of S-polarized light with an incident angle of 45 ° is less than 4.5%, and the average reflective reflectance of (P + S) / 2 polarized light with an incident angle of 45 ° is less than 2.5%. Yes, excellent antireflection ability against polarized waves is realized. The antireflection layer may be formed into three layers by providing a low refractive index layer between the hard coat layer and the high refractive index layer.
Each of the above-mentioned visual average reflectances is the reflectance for each polarized wave when measured by irradiating each polarized light with the antireflection layer of the optical member of the present invention as a measuring surface.
The hard coat layer is formed in the same manner as the hard coat layer on the half mirror layer side. The components of the layer, the coating solution, the forming method, etc. are as described in that section. The thickness of the hard coat layer is preferably 1 to 3 μm.
The low-refractive index layer and the high-refractive index layer of the antireflection layer are formed in the same manner as those of the half mirror layer, and the components of each layer, the coating solution, the forming method and the like are as described in those sections. The refractive index of the low refractive index layer is preferably 1.28 to 1.35, and the thickness is preferably 100 to 120 nm. The refractive index of the high refractive index layer is preferably 1.75 to 1.82, and the thickness is preferably 80 to 170 nm.
The antireflection layer may be formed separately from the formation of the half mirror layer, but when the first layer of the half mirror layer is a high refractive index layer, it is industrially performed as follows. It is efficient. That is, a hard coat layer, a high refractive index layer, and a low refractive index layer are sequentially formed on both sides of a transparent substrate by a dip coating method, one side is protected with a protective film as an antireflection layer, and then a half mirror is placed on the opposite side. The formation of the layer is continued to obtain a predetermined half mirror layer.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. Also, not all combinations of features described in the examples are essential to the solution of the present invention.
The various components and abbreviations used in the following Examples and Comparative Examples, as well as the test methods are as follows.
[P-polarized visual average reflectance]
As mentioned above.
[S-polarized visual average reflectance]
As mentioned above.
[(P + S) / 2-polarized visual average reflectance]
As mentioned above.
[X value and y value in XY chromaticity diagram]
As mentioned above.
[P-polarized visual average reflectance of the antireflection layer surface]
The same antireflection layer was formed on both surfaces, and the P-polarized visual average reflectance on one surface was measured in the same manner as described above.
[S-polarized visual average reflectance of the antireflection layer surface]
The same antireflection layer was formed on both surfaces, and the S-polarized visual average reflectance on one surface was measured in the same manner as described above.
[(P + S) / 2 polarized visual average reflectance of the antireflection layer surface]
The same antireflection layer was formed on both surfaces, and the (P + S) / 2 polarized visual average reflectance on one surface was measured in the same manner as described above.
[Refractive index]
The refractive index of each layer was measured by the following method. The acrylic substrate was coated with a coating solution for forming each layer, and the peak or bottom value was measured using an ultraviolet-visible spectrophotometer "V-650" manufactured by JASCO Corporation. The refractive index of each layer was calculated using the value.
[Clearness of reflected image and transmitted image (rear image)]
A reflected image and a transmitted image were displayed, and the visual clarity was evaluated.
"○": The image was clearly displayed.
"△": Although the strength of the image is weak, an image that can be visually confirmed is displayed.
"X": The image was unclear.
[Clarity of the whole image (stereoscopic image)]
A reflected image and a transmitted image were displayed, and the sharpness of the entire display space was evaluated visually.
"○": Both the reflected image and the transmitted image were displayed in a well-balanced manner, and the image was clear.
"△": The transmitted image was displayed strongly, and the reflected image was displayed weakly.
"X": The reflected image or the transmitted image was strongly displayed, and the other image was unclear.

Example 1
A hard coat layer was formed on a polymethylmethacrylate resin (PMMA) having a thickness of 1 mm by the following method, and a half mirror layer was further formed on the hard coat layer.
[Coating solution for forming a hard coat layer]
Binder (acrylate compound) 176.0 g (100 parts by mass)
・ 4 Functional urethane acrylate 100.0g
・ Pentaerythritol triacrylate 72.0 g
-2-Acryloyloxyethyl hexahydrophthalic acid 4.0 g
Solid silica (average particle size: 10 nm, refractive index: 1.48, solid content 20% by mass,
Dispersion medium IPA) Solid content 69.0 g (39 parts by mass)
γ-glycidoxypropyltrimethoxysilylene
14.8 g (8.4 parts by mass)
Aluminum Tris (Acetylacetonate) 1.2 g (0.7 parts by mass)
1-Hydroxy-cyclohexyl-phenyl-ketone (photopolymerization initiator)
7.3 g (4.1 parts by mass)
0.05N Hydrochloric Acid 3.4g
2- [2-Hydroxy-5- [2- (methacryloyloxy) ethyl] phenyl] -2H-benzotriazole (ultraviolet absorber) 11.3 g
Organic solvent 717.0 g
-Isopropyl alcohol (IPA) 386.0 g
* Containing a dispersion medium of solid silica ・ Acetic acid sec-butyl ester 257.3 g
・ Diacetone alcohol 73.7g
[Coating solution for forming a high refractive index layer: n2]
γ-glycidoxypropyltrimethoxysilylene
14.5 g (100 parts by mass)
Zirconia (average particle size: 50 nm, refractive index: 2.40, solid content 15% by mass,
Dispersion medium Butanol and ethanol mixture)
Solid content 17.9 g (124 parts by mass)
Aluminum Tris (Acetylacetonet) 1.2 g (8.2 parts by mass)
0.05N Hydrochloric Acid 3.3g
Organic solvent 963.1g
Etacol 7 (registered trademark; mixture of ethanol and isopropanol)
861.8g
101.3 g of the dispersion medium of zirconia
[Coating solution for forming a low refractive index layer: n1]
γ-glycidoxypropyltrimethoxysilylene
6.6 g (100 parts by mass)
Hollow silica (average particle size: 60 nm, refractive index: 1.25, solid content 20% by mass,
Dispersion medium IPA) Solid content 12.6 g (192 parts by mass)
Aluminum Tris (Acetylacetonate) 0.5 g (8.2 parts by mass)
0.05N Hydrochloric Acid 1.5g
Organic solvent 978.8 g
・ Normal propyl alcohol (NPA) 195.8g
-Isopropyl alcohol (IPA) 391.5 g
* Includes a dispersion medium for hollow silica ・ Acetic acid sec-butyl ester 391.5 g

First, both sides of the transparent substrate (PMMA, thickness 1 mm) are dip-coated with the coating solution for forming a hard coat layer having the above composition, dried at 60 ° C. for 15 minutes, and then cured by irradiating with ultraviolet rays (500 mJ). A hard coat layer having a thickness of 1.50 μm was formed on both sides of the transparent substrate.
Next, both sides of the transparent substrate having the hard coat layer were dip-coated with the above-mentioned coating solution for forming a high refractive index layer (n2), heat-treated at 90 ° C. for 60 minutes, and had a high refractive index of 169.44 nm in thickness. Layers were formed on both sides. Further, both sides were dip-coated with the coating solution for forming a low refractive index layer (n1) and heat-treated at 90 ° C. for 60 minutes to form a low refractive index layer having a thickness of 113.85 nm on both sides.
After that, one surface is protected by a PET film as an antireflection layer surface (back surface), and the other surface is used as a half mirror layer surface, and the formation of a high refractive index layer and a low refractive index layer is alternately repeated on the half mirror layer surface. Therefore, an optical member having a half-mirror layer having a total number of refractive index layers of 9 and an outermost surface having a high refractive index layer was produced. Table 3 shows the thickness and refractive index of each layer.
From the results of Examples 1 to 5, the thickness of the high-refractive index layers of the first layer and the third layer is in the range of 120 to 440 nm, and the thickness of the outermost surface high-refractive index layer is in the range of 80 to 90 nm. Can be recognized.
When the half mirror layer is an even layer of 9 layers or more, a hard coat layer, a low refractive index layer, a high refractive index layer, and a low refractive index layer are formed in order on both sides of the transparent base material to form three layers. A method of forming an antireflection layer, then protecting one surface with a protective film, and then sequentially forming a half mirror layer on the other surface can also be adopted.
P-polarized visual average reflectance, S-polarized visual average reflectance, (P + S) / 2 polarized visual average reflectance, x-value and y-value in the XY chromaticity diagram, refractive index, back surface of the obtained optical member The visual average reflectance of P-polarized light, the visual average reflectance of S-polarized light on the back surface, the visual average reflectance of the back surface of (P + S) / 2 polarized light on the back surface, and the sharpness of the reflected image, transmitted image, and overall image. It was measured and evaluated according to the above test method. The results are shown in Table 3.
FIG. 1 shows a reflectance distribution diagram of the optical member obtained in Example 1 with respect to a P-polarized wave.
FIG. 2 shows a reflectance distribution diagram of the optical member obtained in Example 1 with respect to the (P + S) / 2 polarized wave.

Examples 2-5
A half mirror layer is formed by using the coating solution for forming a low refractive index layer (n1) having the composition shown in Table 1 and the coating solution (n2) for forming a high refractive index layer having the composition shown in Table 2 in the combination shown in Table 3. An optical member was produced in the same manner as in Example 1 and each characteristic was measured. The results are shown in Table 3.

Comparative Examples 1 to 10
A half mirror layer is formed by using the coating solution for forming a low refractive index layer (n1) having the composition shown in Table 1 and the coating solution (n2) for forming a high refractive index layer having the composition shown in Table 2 in the combination shown in Table 4. An optical member was produced in the same manner as in Example 1 and each characteristic was measured. The results are shown in Table 4.

Comparative Example 1 is an example in which the refractive index of the low refractive index layer exceeds the upper limit value, the reflected image is unclear because the refractive index of the half mirror layer is low, and the reflective image is high in the antireflection layer. Reflected from both the half mirror layer and the antireflection layer, it becomes a double image and the whole image (stereoscopic image) is not clear. Moreover, it was colored. Comparative Example 2 is an example in which the refractive index of the high refractive index layer exceeds the upper limit value, and the transmission image is poor and the whole image is not clear. Comparative Example 3 is an example in which the refractive index of the low refractive index layer does not satisfy the lower limit, and the transmission image is poor and the whole image is not clear. Comparative Example 4 is an example in which the refractive index of the high-refractive index layer does not satisfy the lower limit, the reflected image is poorly reflected, the whole image is not clear, and the image is colored. Comparative Example 5 is an example in which the thickness of the high-refractive index layer on the outermost surface exceeds the upper limit value, and the reflected image is poorly reflected and the whole image is unclear. Comparative Example 6 is an example in which the thickness of the first layer of the half mirror layer is insufficient, the reflection image is slightly poor, and the same phenomenon as in Comparative Example 1 occurs, and the reflection image is mildly doubled. The statue was seen. Comparative Example 7 is an example in which the half mirror layer is five layers, and even if the outermost surface is a high refractive index layer, the reflection image is poor and the whole image is unclear. Comparative Example 8 is an example in which the half mirror layer is six layers, and the reflection image is very poor and the whole image is extremely unclear. Comparative Examples 9 and 10 are examples in which the refractive index of the low refractive index layer exceeds the upper limit value, and the reflected image is unclear and is a double image, and the whole image is not clear.
FIG. 3 is a schematic view showing a typical layer structure of the optical member of the present invention.
FIG. 4 is a schematic view showing a usage mode of the optical member of the present invention.

Claims

An optical member provided with a transparent substrate, a hard coat layer, and a half mirror layer in this order.
In the half mirror layer, nine or more layers having a high refractive index having a refractive index of 1.75 to 1.82 and a low refractive index layer having a refractive index of 1.28 to 1.35 are alternately laminated to form a high refractive index. It is formed by laminating so that the rate layer is on the outermost surface, and the thickness of the high refractive index layer on the outermost surface is 80 to 90 nm.
The average reflectance of P-polarized light with an incident angle of 45 ° at a wavelength of 380 to 780 nm is 30% to 40%, the average reflectance of S-polarized light with an incident angle of 45 ° is 70% to 85%, and the incident angle is 45 °. The visual average reflectance of (P + S) / 2 polarization is 50% to 65%, and x: 0.30 to 0.32 and y: 0.32 to 0.34 in the XY chromaticity diagram. Optical member.
The optical member according to claim 1, wherein the thickness of the first layer and the third layer from the hard coat layer side of the half mirror layer is 120 to 440 nm.
The high refractive index layer has a curable composition containing 120 to 470 parts by mass of metal oxide particles and 8 to 10 parts by mass of a metal chelate compound with respect to 100 parts by mass of a binder component composed of an alkoxysilane compound or a hydrolyzate thereof. The optical member according to claim 1, which is a cured product of an object.
A curable composition in which the low refractive index layer contains 65 to 330 parts by mass of hollow silica particles and 8 to 10 parts by mass of a metal chelate compound with respect to 100 parts by mass of a binder component composed of an alkoxysilane compound or a hydrolyzate thereof. The optical member according to claim 1, which is a cured product of the above.
A hardcourt layer and an antireflection layer are included in this order on the surface opposite to the surface on which the half mirror layer of the optical member is formed.
The antireflection layer includes a high refractive index layer and a low refractive index layer from the hard coat layer side, and the visual average reflectance of P-polarized light having an incident angle of 45 ° at a wavelength of 380 to 780 nm is less than 0.5%, and the incident angle. A claim having antireflection ability such that the visual average reflectance of 45 ° S-polarized light is less than 4.5% and the visual average reflectance of (P + S) / 2 polarized light having an incident angle of 45 ° is less than 2.5%. The optical member according to 1.
The method for manufacturing an optical member according to any one of claims 1 to 5, wherein each layer of a hard coat layer, a half mirror layer, and an antireflection layer to be installed as needed is configured on a transparent substrate. A method for producing an optical member, which comprises applying a curable composition that gives rise to a cured product, and then curing the composition to sequentially form the optical member.