WO2019073946A1

WO2019073946A1 - Cover member

Info

Publication number: WO2019073946A1
Application number: PCT/JP2018/037519
Authority: WO
Inventors: 一色　眞誠; 池田　徹; 鷹典下坂; 稔玉田; 貴章村上
Original assignee: Ａｇｃ株式会社
Priority date: 2017-10-10
Filing date: 2018-10-09
Publication date: 2019-04-18
Also published as: JP7140134B2; JPWO2019073946A1

Abstract

The present invention pertains to a cover member provided with a transparent substrate comprising a first main surface having first recesses and protrusions and a second main surface having second recesses and protrusions, a high refractive index layer, and a resin layer, wherein the high refractive index layer and the resin layer are provided, in this order, on the second main surface-side of the transparent substrate, and, at a wavelength of 550 nm, when the refractive index of the transparent substrate is defined as n1, the refractive index of the resin layer is defined as n2, and the refractive index of the high refractive index layer is defined as n3, formulas 1 and 2 are satisfied. Formula 1: n1 < n3 Formula 2: n2 < n3

Description

Cover member

The present invention relates to a cover member.

In various devices (for example, image display devices (for example, liquid crystal displays, organic EL displays, plasma displays, etc.) provided in TVs, personal computers, smart phones, mobile phones, vehicles etc.), indoor lighting such as fluorescent lamps and solar light When external light such as light is reflected on the display surface, the reflected image reduces the visibility.

Antiglare treatment (AG treatment) is performed on the display surface of the image display device as a method of suppressing the reflection of external light. When a glass substrate is used on the display surface of the image display device, chemical or physical surface treatment is performed on the surface of the glass substrate to form irregularities, and then hydrofluoric acid or the like is used to adjust the surface shape. A method of etching is known (see Patent Document 1).

Further, as a method of suppressing the reflection of external light, there is also a method of disposing an antiglare film on the display surface side of the image display device. The antiglare film has irregularities on the surface, diffuses and reflects external light, and blurs a reflected image. Such an antiglare film is formed, for example, by applying a coating solution containing a hydrolyzable organosilicon compound such as a hydrolytic condensation product of alkoxysilane as a silica precursor to the surface of a light transmitting substrate by a spray method, It forms by baking (for example, refer patent document 2).

There is also a method of disposing a transparent substrate provided with a low reflection film on the display surface of the image display device, suppressing reflection itself of incident light on the transparent substrate, and blurring the reflected image. As a low reflection film, a single layer film made of a low refractive index material, and a multilayer film obtained by combining a layer made of a low refractive index material and a layer made of a high refractive index material are known. Further, as a low reflection film, a film formed of a fluorine-containing hydrolyzable organosilicon compound is also known (see, for example, Patent Documents 3 to 6).

Moreover, as a base material having high visibility and high antiglare property, a member provided with a smooth one main surface and the other main surface having a texture, a metal layer formed on the texture, or a refractive index of the member A laminated structure formed of a dielectric layer having a refractive index different from that of the above and a member having a refractive index similar to that of the member is known (for example, Patent Document 7). However, the surface was a smooth surface, and it was not configured to be compatible with the antiglare property of the cover surface and the glare suppression required as a cover member for a display element.

Japanese Patent Application Laid-Open No. 61-36140 International Publication 2016/021560 Japanese Unexamined Patent Publication No. 64-1527 Japanese Patent Application Laid-Open No. 2003-344608 Japanese Patent Application Laid-Open No. 2002-79616 International Publication No. 2005/121265 Japanese Patent No. 6082107

When the cover member is provided on the display surface side of the image display device, the antiglare treatment (AG treatment) may be performed on the display surface side of the cover member or the antiglare film may be disposed on the display surface side of the cover member (hereinafter referred to as In the antiglare layer, it is possible to suppress a decrease in the visibility of the image due to the reflection of external light on the display surface. However, at the same time, in the antiglare layer, the higher the antiglare property, the lower the visibility. This is because surface reflection scattering representing antiglare property and transmission scattering representing visibility are expressed by the difference in refractive index at the interface between the uneven surface of the antiglare layer and air. In addition, as the antiglare property is higher, glare occurs on the antiglare treatment (AG treatment) surface and the antiglare film surface, and the visibility further decreases.
Therefore, high glare resistance, high visibility, and low glare could not be achieved simultaneously.

An object of the present invention is to provide a cover member capable of simultaneously achieving high antiglare property, high visibility, and low glare.

In order to achieve the above object, the present invention provides a transparent substrate comprising a first main surface having a first uneven portion and a second main surface having a second uneven portion; a high refractive index layer; and a resin layer The high refractive index layer and the resin layer are provided in this order on the second main surface side of the transparent substrate, in this order.
A cover satisfying Formula 1 and Formula 2 below, where n _{1 is} the refractive index of the transparent base, n _{2 is} the refractive index of the resin layer, and n ₃ is the refractive index of the high refractive index layer, at a wavelength of 550 nm. Provide a member.
n ₁ <n ₃ formula 1
n ₂ <n ₃ formula 2

In the cover member of the present invention, a value obtained by subtracting the reflectance at the interface between the first main surface and the air from the reflectance of the cover member measured from the first main surface side is 0.1% or more and 4% It is preferable that it is the following.

In the cover member of the present invention, the refractive index n ₂ at a wavelength 550nm of the resin layer is preferably from 1.4 to 1.8.

In the cover member of the present invention, the absolute value | n ₁ −n ₂ | of the difference between the refractive index n ₁ and the refractive index n ₂ is preferably 0.1 or less.

In the cover member of the present invention, it is preferable that the refractive index n ₃ of a wavelength 550nm of the high refractive index layer is 2.0 or more.

In the cover member of the present invention, the thickness of the high refractive index layer is preferably 5 to 80 nm.

In the cover member of the present invention, the high refractive index layer is titanium dioxide (TiO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ), silicon nitride (Si ₃ N ₄ ), It is preferable to contain at least one selected from the group consisting of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), zinc oxide (ZnO), and tin dioxide (SnO ₂ ).

In the cover member of the present invention, the outermost surface of the first uneven portion and the second uneven portion has a surface roughness Rq of 0.02 μm or more and 0.3 μm or less, and an average length RSm of elements of the roughness curve is 8 μm. The thickness is preferably 50 μm or less.
In the cover member of the present invention, it is preferable that the first uneven portion and the second uneven portion be formed by an antiglare treatment.

In the cover member of the present invention, the transparent substrate is preferably made of glass.
In the cover member of the present invention, the transparent substrate is preferably made of chemically strengthened glass.
In the cover member of the present invention, the transparent substrate preferably has a bent portion.

According to the cover member of the present invention, high antiglare property, high visibility and low glare can be achieved simultaneously.

FIG. 1 is a cross-sectional view schematically showing one structural example of the cover member of the present invention. FIG. 2 is a diagram showing a method of measuring a reflection image diffusive index.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Cover member 10>
FIG. 1 is a cross-sectional view schematically showing one structural example of the cover member 10 of the present invention.
The cover member 10 shown in FIG. 1 has a transparent base 11 having a first major surface 12 having a first uneven portion and a second major surface 13 having a second uneven portion, a high refractive index layer 15 and a resin layer 14. The high refractive index layer 15 and the resin layer 14 are provided on the second major surface 13 of the transparent substrate 11 in this order. Further, the cover member 10 shown in FIG. 1 has a refractive index n ₁ of the transparent substrate 11 at a wavelength of 550 nm, n ₂ of the refractive index of the resin layer 14, n of the refractive index of the high refractive index layer 15. _{When set to 3} , the following formulas 1 and 2 are satisfied.
n ₁ <n ₃ formula 1
n ₂ <n ₃ formula 2

The cover member 10 shown in FIG. 1, the refractive index n ₃ of the wavelength 550nm is the second major surface 13 of the above formula 1 and the high-refractive index layer 15 is a transparent substrate 11 that satisfies the equation 2, between the resin layer 14 By being present, the diffuse reflection component of the light incident on the high refractive index layer 15 from the side of the first major surface 12 of the transparent substrate 11 can be increased as compared with the case where the high refractive index layer 15 is not present. Thereby, the antiglare property which can make the reflected image reflected in the cover member 10 from the 1st main surface side of the transparent base material 11 unclear can be increased.

Here, light scattering is roughly divided into “surface scattering” and “internal scattering”.
“Internal scattering” is not an interface with air, but has a structure having an interface with a refractive index difference inside a series of cover members 10 added to the surface of an image display element, such as a transparent substrate 11 and a resin layer 14 In the case of the interface, it means scattering that occurs according to the interface shape. Internal scattering is divided into "internal transmission scattering" and "internal reflection scattering". "Internal transmission scattering" means scattering generated when transmitted light passes through an interface between containing particles and layers having different refractive indexes, and the visibility deteriorates if the internal transmission scattering increases. "Internal reflection scattering" means scattering generated when incident light is reflected at the interface between containing particles and layers having different refractive indexes, and as the internal reflection scattering increases, the antiglare property increases.

“Surface scattering” means scattering occurring at the interface between air having a refractive index difference and the cover member 10. Specifically, it is divided into “surface transmission scattering” and “surface reflection scattering”. “Surface transmission scattering” means scattering at the interface between the air of the transmission light and the cover member 10, and the visibility decreases as the surface transmission scattering increases. "Surface reflection scattering" means scattering at the interface between the air of the incident light and the cover member 10, and as the surface reflection scattering becomes larger, the antiglare property becomes higher.

Furthermore, "transmission scattering" means the sum of internal transmission scattering and surface transmission scattering, and as the transmission scattering increases, the visibility decreases.

Also, "specular reflection" means, in reflection, reflection reflected at the same angle as the incident angle to the surface. By "diffuse reflection" is meant, in reflection, the reflection that is reflected at an angle different from the angle of incidence with respect to the surface and diffused as a whole. The surface in this case refers not to the inclined surface of each of the fine surface irregularities but to a plane parallel to a plane including the average height of the irregularities of the transparent substrate having the irregularities on the surface.

Conventionally, the surface reflection scattering that increases the antiglare property and the transmission scattering that reduces the visibility both have the same interface, that is, the interface between the uneven surface of the antiglare layer (the first uneven portion) and the air (here, In 1 principal surface 12), it was expressed by those refractive index differences. Therefore, when the high antiglare property is exhibited, the visibility is reduced and the glare property is deteriorated. As a result, high glare resistance, high visibility and low glare could not be simultaneously achieved.

According to the present invention, at the interface formed by the second major surface 13 having the second uneven portion, the high refractive index layer 15, and the resin layer 14, the transparent base 11 / high refractive index layer 15 interface and the high refractive index layer The 15 / resin layer 14 interface is in a substantially parallel relationship microscopically. Further, the difference between the refractive index n ₂ of the refractive index n ₁ and the resin layer 14 of the transparent substrate 11 is small, the film thickness of the high refractive index layer 15 is very thin. From the above, the transmitted light is hardly scattered and does not increase the internal transmission scattering. On the other hand, the interface between the transparent substrate 11 and the high refractive index layer 15 has a large difference in refractive index and an angle with respect to the vertically incident light, so that internal reflection scattering is developed. From the above, only the antiglare property can be improved by the internal reflection scattering without increasing the internal transmission scattering. Further, by suppressing the surface reflection scattering of the first major surface 12, transmission scattering is suppressed, and low glare can be obtained. As a result of the above, high anti-glare property, high visibility and low glare can be simultaneously achieved as the cover member 10.

<Transparent base 11>
The transparent substrate 11 in the cover member 10 shown in FIG. 1 prepares a transparent plate having a first major surface 12 and a second major surface 13, and the first uneven portion is transparent on the first major surface 12 of the transparent plate. The second uneven portion is formed on the second main surface 13 of the plate. In the present specification, the surface shape of the transparent substrate 11, more specifically, the surface shape of the first major surface 12 and the second major surface 13 of the transparent substrate 11, and more specifically, the first major surface The surface roughness Rq and the average length RSm of the elements of the roughness curve are used as an indicator of the surface shape of the first uneven portion 12 and the second uneven portion of the second main surface. The surface roughness Rq and the average length RSm of the elements of the roughness curve can be obtained by measurement according to JIS B0601-2001.

[Transparent plate]
Glass, resin etc. are mentioned as a material of a transparent plate. Examples of the resin include polyethylene terephthalate, polycarbonate, triacetyl cellulose, and polymethyl methacrylate.
Above all, in terms of safety and strength, the transparent plate is preferably glass. Furthermore, use of the glass for a vehicle-mounted display member is preferable also from a viewpoint of high heat resistance and high weather resistance.

When the transparent plate is glass, for example, it is preferable that the transparent plate be subjected to a strengthening treatment in order to ensure the mechanical strength and the scratch resistance necessary for the cover member 10 of the in-vehicle display member. As the strengthening treatment, both of physical strengthening treatment and chemical strengthening treatment can be used, but the transparent plate is preferably chemically strengthened glass, from the viewpoint that relatively thin glass can be treated for strengthening.

The glass composition that can be used for the transparent plate is non-alkali glass when no chemical strengthening treatment is performed, and soda lime glass is used when chemical strengthening treatment is performed, for example, soda lime silicate glass, aluminosilicate glass, borate glass, Lithium aluminosilicate glass and borosilicate glass can be mentioned. Even if the thickness is thin, a high strength glass can be obtained by a strengthening treatment even if it is thin and high strength can be obtained, and aluminosilicate glass is preferable from the viewpoint of being suitable as an article disposed on the viewing side of the image display device.

The maximum value of surface compressive stress (CS) of the transparent plate is preferably 400 MPa or more, more preferably 500 MPa or more, and still more preferably 600 MPa or more. The compressive stress layer depth (DOL) of the transparent plate is preferably 10 μm or more. By setting the surface compressive stress and the compressive stress layer depth of the transparent plate in the above range, excellent strength and scratch resistance can be imparted to the main surface of the transparent plate.

0.3 mm or more is preferable and, as for the thickness of a transparent plate, 0.5 mm or more is more preferable. Moreover, 5 mm or less is preferable, as for the thickness of a transparent plate, 3 mm or less is more preferable, and 2 mm or less is more preferable. Within this range, the final product can be made less likely to break.

The transparent plate may comprise at least one or more bends. Although the shape which combined the bending part and the flat part, the shape which becomes the whole bending part, etc. are mentioned, a shape is not specifically limited if it has a bending part. Recently, in the case where a cover member having a bent portion is used for a display device, in various devices (televisions, personal computers, smartphones, car navigations, etc.), those in which the display surface of the display panel is a curved surface have appeared. The bent portion can be manufactured in accordance with the shape of the display panel, the shape of the housing of the display panel, or the like. In addition, a "flat part" means the part whose average curvature radius is more than 1000 mm, and the "bending part" means the part whose average curvature radius is 1000 mm or less.

When the refractive index at a wavelength of 550nm of the transparent plate and n _1, n ₁ is preferably 1.45 to 1.62. This is because the refractive index n ₁ increases the refractive index difference at the interface between the 1.62 larger than air, glare surface reflection is increased becomes more visible. The refractive index n ₁ is for easily available as a highly transparent plate transmittance and 1.45 or more.
The refractive index n ₂ and n ₃ the index of refraction n ₁ and will be described later, of the visible light wavelength region, because most visibility is high at a wavelength of 550 nm, and a value at a wavelength of 550 nm.
For the refractive index, a phase difference Δ between s-polarized light and p-polarized light and a reflection amplitude ratio tan ψ are measured using a spectroscopic ellipsometer (M-2000 manufactured by J. A. Woolam Co., Ltd.). The refractive index is obtained by fitting the refractive index of each layer in the wavelength range of 400 to 700 nm according to Cauchy's dispersion formula. In addition, even if it is a measuring method of refractive index except the above-mentioned method, it can be used if it can measure similarly.

[Uneven part]
The transparent base material 11 in the cover member 10 shown in FIG. 1 is provided with a first uneven portion on the first main surface 12 and a second uneven portion on the second main surface 13. The Rq of the outermost surface of the first uneven portion and the second uneven portion is preferably 0.02 μm or more and 0.3 μm or less in order to simultaneously achieve high antiglare property, high visibility, and low glare. 0.25 micrometers or less are more preferable.
Here, the antiglare property means the ability to reduce the glare of the reflected light due to the reflection of the light source by scattering the reflected light, and the glare can be reduced as the high antiglare property is achieved. In the case of a cover member for a display element, visibility means the ability to clearly show the displayed characters, figures and the like, and the clearer is the more the transmitted light is scattered. That is, the higher the visibility, the more clearly visible. Sparkle means that, when the cover member is used for a pixel matrix type display element, a large number of light particles having a cycle larger than that of the pixel matrix are observed on the surface of the cover member, and the degree of inhibition of visibility is The lower the glare, the less the particles of light are observed, and the visibility is improved.

The RSm of the outermost surface of the first uneven portion and the second uneven portion is preferably 8 μm to 50 μm in order to simultaneously achieve high antiglare property, high visibility, and low glare, and more preferably 10 μm to 22 μm or less preferable. The surface shapes of the first uneven portion and the second uneven portion may be the same or different, and are not particularly limited.

In order to form the first uneven portion and the second uneven portion on the first main surface 12 and the second main surface 13 of the transparent plate to obtain the transparent substrate 11, a so-called antiglare treatment may be performed. The antiglare treatment to be carried out for this purpose is not particularly limited, and may be formed by processing the main surface of the transparent plate itself, or may be separately formed by a deposition treatment method. When processing the main surface of the transparent plate itself, a chemical treatment method with etching treatment such as frost treatment may be used, or a physical treatment method such as sand blast treatment may be used.
When using a chemical treatment method involving an etching process, for example, by etching the first major surface 12 and the second major surface 13 of the transparent plate with a hydrogen fluoride (HF) aqueous solution having a concentration of 15 to 50%, The first uneven portion and the second uneven portion can be formed on the first major surface 12 and the second major surface 13. The concavo-convex shape can be controlled by changing the concentration and processing time of the HF aqueous solution used for the etching process. Thereby, Rq and RSm of the 1st principal surface 12 and the 2nd principal surface 13, and, more specifically, Rq and RSm of the outermost surface of the 1st concavo-convex part and the 2nd concavo-convex part can be controlled. For the etching process, a chemical solution in which potassium fluoride is mixed with a hydrogen fluoride aqueous solution, or a mixed chemical solution of hydrogen fluoride and hydrogen chloride may be used.

In addition, as a deposition treatment method, a known wet coating method (spray coating method, electrostatic coating method, spin coating method, dip coating method, die coating method, curtain coating method, screen coating method, ink jet method, flow coating method, gravure coating Methods, bar coat methods, flexo coat methods, slit coat methods, roll coat methods, etc. can be used. Examples of the film formed by the deposition treatment include a film containing silica as a main component. Here, the main component is a component which is contained in an amount of 70% by mass or more in the film at an oxide conversion content. The film may contain fine particles, and fine particles such as scaly and spherical particles can be used as the fine particles. By using the fine particles, a desired uneven shape can be formed. In addition, as another antiglare treatment, a film having known antiglare properties can also be formed by sticking to the first main surface and the second main surface. In addition, the formation method of a 1st uneven part and a 2nd uneven part may be same or different, and there is no restriction | limiting in particular.

<Resin layer 14>
The resin layer 14 in the cover member 10 shown in FIG. 1 is provided on the side of the second main surface 13 of the transparent substrate 11. The resin layer 14 has functions such as, for example, high visible light transmittance, adhesiveness, adhesiveness, and high durability.

The resin layer 14 is not particularly limited, and a thermoplastic resin such as acrylic, an adhesive resin, an adhesive resin, or the like can be used. Among them, adhesive resins are preferable, and adhesives such as acrylic adhesives, silicone adhesives, butadiene adhesives, and polyurethane adhesives can be used. Acrylic-based pressure-sensitive adhesives are preferable from the viewpoint of being very high in visible light transmittance and suitable for use as a cover glass for display devices and the like.

An acrylic adhesive is a polymer containing an acrylic monomer unit as a main component. Examples of acrylic monomers include (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, and alkyl esters thereof.

In the acrylic pressure-sensitive adhesive, in order to increase the cohesion of the pressure-sensitive adhesive, it is preferable to use a monomer having a functional group which can be a crosslinking point, such as a hydroxyl group or a glycidyl group. Preferred examples of the monomer having a functional group that can be a crosslinking point include hydroxyethyl (meth) acrylate and glycidyl (meth) acrylate.

When using a monomer having a functional group which can be a crosslinking point, it is preferable to add a crosslinking agent. By reacting a crosslinking agent with a functional group, a polymer having a crosslinking point can be obtained, and cohesion can be secured when it is used as an adhesive. Examples of the crosslinking agent include melamine resin, urea resin, epoxy resin, metal oxide, metal salt, metal hydroxide, metal chelate, polyisocyanate, carboxyl group-containing polymer, acid anhydride, polyamine and the like, and the crosslinking point It selects suitably according to the kind of functional group which may become.

The resin layer 14 in the cover member 10 shown in FIG. 1 preferably has an adhesion of 5.5 N or more to an object to which the resin layer 14 is to be bonded, specifically, the front transparent substrate of the image display device. 5N to 20N is more preferable, and 5.5N to 10N is more preferable. In order to set the adhesion strength to 5.5 N or more, a polar group may be introduced, and a monomer or polymer having a polar group, or an additive such as a silane coupling agent may be blended. When the resin layer 14 has a laminated structure of two or more layers, the adhesion is the adhesion of the entire resin layer 14 of the laminated structure.
Here, the adhesion can be measured by the method of JIS Z 0237: 2009, using, for example, 90 ° peel test jig evaluation (model number P90-200N) manufactured by IMADA CO., LTD.

The thickness of the resin layer 14 in the cover member 10 shown in FIG. 1 is preferably in the range of 10 μm to 500 μm, and more preferably in the range of 50 μm to 300 μm. If the thickness of the resin layer 14 is less than 10 μm, air bubbles may be easily mixed at the time of bonding. If the thickness of the resin layer 14 is 500 μm or less, it can be easily processed into a desired shape or thickness.
When the resin layer 14 has a laminated structure of two or more layers, the thickness of the resin layer 14 is the thickness of the entire resin layer 14 of the laminated structure.

The resin layer 14 of the cover member 10 shown in FIG. 1, and the refractive index at a wavelength of 550nm and n _2, the refractive index n ₂ is preferably 1.4-1.8. This is the refractive index substantially equal to that of the refractive index n _1, in order to practically accessible. As the value of the refractive index n ₂ is close to the refractive index n _1, scattering of light transmitted through the resin layer 14 / high refractive index layer 15 / transparent substrate 11 is reduced, the visibility is improved.
In addition, as long as the refractive index in wavelength 550 nm of each layer which comprises the resin layer 14 satisfy | fills the said range, the resin layer 14 may be a laminated structure of two or more layers. The same resin layer may be used for each layer constituting the resin layer 14, or different resin layers may be used.

As the adhesive refractive index n ₂ satisfies the above range, for example, manufactured by Soken Chemical Engineering Co., Ltd. optical pressure-sensitive adhesive SK dyne (registered trademark) series, Henkel Corporation optically transparent adhesive Loctite (registered trademark) series, manufactured by Nitto Denko Corporation The transparent adhesive sheet LUCIACS (registered trademark) CS986 series for optics is mentioned.

<High refractive index layer 15>
The high refractive index layer 15 is a layer having a function of increasing the reflected light scattering without scattering the transmitted light, suppressing the reduction of the visibility index value T described later and increasing the reflected image diffusion index value R.
The high refractive index layer 15 is provided on the side of the second main surface 13 of the transparent substrate 11.
Two or more layers including the high refractive index layer 15 may be provided between the second major surface 13 of the transparent substrate 11 and the resin layer 14.

A configuration in which two or more layers including the high refractive index layer 15 exist between the second major surface 13 and the resin layer 14 can be mentioned. As a specific example, assuming that the refractive index at a wavelength of 550 nm of the high refractive index layer 15 is n ₃ , two layers having a refractive index lower than the refractive index n ₃ (hereinafter referred to as “low refractive index layer”). And a three-layer structure in which the high-refractive-index layer 15 is sandwiched between the two high-refractive-index layers 15 and a low-refractive-index layer sandwiched between the two high-refractive-index layers 15. . Furthermore, in addition to the three-layer structure described above, a structure in which a high refractive index layer 15, a low refractive index layer, and an intermediate refractive index layer having a refractive index between those of these layers is further stacked The structure which exists between the main surface 13 and the resin layer 14 is mentioned.

A wet film formation method or a dry film formation method can be used to form the high refractive index layer 15 or the low refractive index layer. Among them, dry film forming methods such as vacuum evaporation method, ion beam assisted evaporation method, ion plate method, sputtering method and plasma CVD method are preferable. This is because the film can be formed relatively uniformly following the shape of the base. As the surface shape of the base and the surface shape after film formation are closer to parallel, the refraction angle of the transmitted light when passing through the interface decreases, so that high antiglare property is exhibited and visibility is improved at the same time. Here, “parallel” means that a high refractive index layer having a substantially uniform thickness or two or more layers including the high refractive index layer 15 are formed in accordance with the shape of the antiglare treated surface of the base. Indicates the status.

Refractive index n ₃ of the high refractive index layer 15 of the cover member 10 shown in FIG. 1 is 2.0 or more. This increases the reflection at about the transparent substrate 11 / high refractive index layer 15 interface is large difference between the refractive index n ₁ of the transparent substrate 11, because the antiglare property is increased. Furthermore, adjusting the film thickness of the high refractive index layer 15 makes it easy to obtain any antiglare property.

The film thickness of the high refractive index layer 15 in the cover member 10 shown in FIG. 1 is not particularly limited, but is preferably 5 to 80 nm, for example. This is because when the film thickness is smaller than 5 nm, it is difficult to form a continuous film. In addition, when the film thickness of the high refractive index layer 15 is greater than 80 nm, the degree of parallelism between the high refractive index layer 15 / transparent substrate 11 interface and the high refractive index layer 15 / resin layer 14 interface is degraded. It is because the transmitted light which permeate | transmits the layer 14 / high refractive index layer 15 / transparent base material 11 is scattered, and visibility becomes easy to fall.
When two or more layers including the high refractive index layer 15 exist between the second major surface 13 of the transparent substrate 11 and the resin layer 14, the film thickness of the high refractive index layer 15 is high refractive index The total thickness of two or more layers including the ratio layer 15.

Construction material of the high refractive index layer 15 of the cover member 10 shown in FIG. 1 is not particularly limited as long as satisfying the refractive index n ₃ described above. The constituent material of satisfying high refractive index layer 15 whose refractive index n ₃ described above, titanium dioxide (TiO _2), niobium pentoxide (Nb ₂ O _5), tantalum pentoxide (Ta ₂ O _5), silicon nitride (Si ₃ N _4), alumina (Al ₂ O _3), aluminum nitride (AlN), zinc oxide (ZnO), include tin dioxide (SnO ₂₎ or the like. The high refractive index layer 15 may be configured of only one type described above, or may be configured of two or more types.

In the case of lamination of the high refractive index layer 15 and the low refractive index layer, silicon dioxide (SiO ₂ ), BaF ₂ , CaF ₂ , LaF ₃ , LiF, MgF ₂ , cryo, as a constituent material of the low refractive index layer And light (Na ₃ AlF ₆ ), thiolite (Na ₅ Al ₃ F ₁₄ ), NdF ₃ , NaF, YF _{3 and the} like. These constituent materials may be doped with Al, B, P or the like. Moreover, it is preferable that 70 mass% or more of the constituent material of the said low refractive index layer is contained as a main component in a low refractive index layer.

The resin layer 14 may be formed on the high refractive index layer 15 by a known method according to the resin layer to be used.
As an example, the method of forming by application (further drying and (semi) curing) of an adhesive and the method of forming using an adhesive tape are exemplified.
In addition, the cover member 10 is stored in the state which stuck the protective film on the surface of the resin layer 14 after formation.

From the above, in the cover member 10 shown in FIG. 1, the high refractive index layer 15 is sandwiched between the transparent base 11 and the resin layer 14 having a small absolute value | n ₁ −n ₂ | of refractive index difference, and the resin layer 14 / The interface of the high refractive index layer 15 and the interface of the high refractive index layer 15 / the transparent substrate 11 are almost parallel. Therefore, light incident from the resin layer is refracted once by the high refractive index layer, but when incident from the high refractive index layer to the transparent substrate, it is refracted in the direction opposite to the first refraction, and as a result, the incident light is mostly It travels to the transparent substrate 11 without refraction (the traveling direction does not change). Therefore, the presence of the high refractive index layer 15 between the second main surface 13 having the irregularities and the resin layer 14 does not increase the transmission scattering and does not deteriorate the visibility or the glare, as described above. The effect of improving the antiglare property can be obtained by the internal reflection scattering. The absolute value | n ₁ −n ₂ | of the refractive index difference is preferably 0.1 or less.

Moreover, in the cover member 10 shown in FIG. 1, the reflectance at the interface between the first main surface 12 of the transparent base material and the air from the reflectance of the cover member 10 measured from the side of the first main surface 12 of the transparent base material 11 It is preferable that the value which deducted is 0.1% or more and 4% or less. Within this range, the antiglare property is improved by the increase of the reflection and scattering, while the transmitted light from the resin layer 14 side is not scattered, so high visibility and low glare can be achieved simultaneously, and the optical characteristics are excellent. Is obtained.

In the cover member 10 shown in FIG. 1, also in the case where two or more layers including the high refractive index layer 15 are present between the second major surface 13 of the transparent substrate 11 and the resin layer 14, the transparent substrate A value obtained by subtracting the reflectance at the interface between the first main surface 12 of the transparent substrate 11 and the air from the reflectance of the high refractive index layer 15 measured from the first main surface 12 side of T.11 is 0. 1% or more and less than 4% is preferable, 0.1% or more and less than 3% is more preferable, 0.1% or more and less than 2% is more preferable, and 0.1% or more and less than 1% is particularly preferable.

As described above, according to the cover member 10 shown in FIG. 1, high antiglare property, high visibility and low glare can be achieved simultaneously.

The antiglare property, glare, and visibility can be evaluated by the reflection image diffusive index value R, the glare index value S, and the visibility index value T, respectively, and each measurement method will be described below.

[Reflected image diffusivity index value R]

In the present specification, a reflection image diffuseness index value (R), which is measured according to the following procedure, is used as an antiglare index. The reflection image diffusiveness index value indicates how much the reflection image of an object (for example, illumination) placed around the glass plate matches the original object, and is observed. It has been confirmed that a good correlation is shown with the judgment result of the antiglare property by visual observation of the person. For example, a glass plate having a small (close to 0) reflective image diffusive index value R is inferior in antiglare property, and conversely, a glass showing a larger reflective image diffusive index value R (larger closer to 1) The board has good antiglare properties.

A method of measuring the reflection image diffusive index value R of the cover member 50 having the antiglare function will be described with reference to FIG. FIG. 2 schematically shows an example of a measuring apparatus used when measuring the reflection image diffusive index value R.
Although the cover member 50 having the antiglare function shown in FIG. 2 corresponds to the cover member 10 in FIG. 1, the description of the resin layer 14 and the high refractive index layer 15 in FIG. 1 is omitted. Further, the first main surface 52 and the second main surface 53 shown in FIG. 2 correspond to the first main surface 12 and the second main surface 13 of the transparent base 11 in FIG. 1, respectively.
When measuring the reflection image diffusive index value R, the cover member 50 is usually subjected to a process for preventing light reflection on the surface of the resin layer 14 in FIG. 1 opposite to the surface in contact with the high refractive index layer 15. This process is implemented to eliminate the effects of reflections from non-target surfaces. The “processing for preventing light reflection” includes, for example, applying black ink or the like to the surface of the resin layer 14 to blacken the surface. In addition, a black ink layer may be provided on the surface of the resin layer 14 to prevent reflection of light from the surface. Alternatively, reflection of light from the second major surface may be prevented in another way.

As shown in FIG. 2, the measuring device 70 has a linear light source device 71 and a surface brightness measuring device 75, and a sample to be measured, that is, a cover member having an antiglare function (or antiglare processing) in the measuring device 70. (A transparent substrate having an antiglare function) 50 is disposed. The linear light source device 71 includes a light source 711 and a black flat plate 712, and the black flat plate 712 is provided with the light source 711 in a slit-like opening. The cover member 50 having the antiglare function has a first main surface 52 on which a layer having the antiglare function is formed, and a second main surface 53. The linear light source device 71 is disposed toward the cover member 50 having the antiglare function and in the direction perpendicular to the paper surface in FIG. The surface luminance measuring unit 75 is disposed at the center of the linear light source device 71 in the direction perpendicular to the paper surface, on a plane perpendicular to the linear light source device 71. The focus of the surface luminance measuring device 75 is focused on the image of the linear light source device 71 reflected by the cover member 50. That is, the plane on which the image is focused is made to coincide with the black flat plate 712. Here, among the light emitted from the linear light source device 71 and reflected by the cover member 50 and incident on the surface luminance measuring device 75, a light beam having the same incident angle θi and reflection angle θr (hereinafter referred to as first incident light 731; Focusing on the reflected light 732 of 1), θi = θr = 5.7 °.

The cover member 50 having the antiglare function is disposed such that the first major surface 52 is on the side of the linear light source device 71 and the surface luminance measuring instrument 75. A black plate is disposed on the second major surface 53 side of the cover member 50. Accordingly, the light detected by the surface luminance measuring device 75 is the reflected light reflected by the cover member 50 having the antiglare function.

Next, the measurement method will be described. For example, focusing on the light beams 733 and 734 having a difference θr−θi = 0.5 ° between the incident angle θi and the reflection angle θr, the light beam 734 is scattered by the cover member 50 in the direction shifted 0.5 ° from the regular reflection. Represents the component. A light beam coming from this direction is observed by the surface brightness measuring device 75 as an image of a portion where the black flat plate 712 and the virtual incident light 733-2 (a light beam incident at an incident angle equal to the reflection angle of the light beam 734) intersect. . That is, when the surface luminance is acquired by the surface luminance measuring device 75, the light scattered by the first major surface 52 of the cover member 50 is centered on the bright line corresponding to the regular reflection of the light beam emitted from the linear light source device 71 An image that spreads to the left and right of the bright line is obtained. A luminance cross-sectional profile in a direction perpendicular to the bright line is extracted. The data may be integrated in the direction parallel to the bright line to increase the measurement accuracy.

First, the luminance of the first reflected light 732 that is specularly reflected among the light incident on the first major surface 52 of the cover member 50 having the antiglare function is R ₁ . The incident angle θi of the first incident light 731 is 5.7 °, and the reflection angle θr of the first reflected light 732 is 5.7 °. The angle at which the direction of the light beam is changed by the reflection by the cover member 50 is written as θr−θi, which is 0 °. Since an error is actually included, θr−θi is in the range of 0 ° ± 0.1 °.

Next, the luminance of the

light beams

733 and 734 having a difference θr−θi = 0.5 ° between the incident angle θi and the reflection angle θr is R ₂ . This ray represents a component scattered by the cover member 50 in the direction deviated from the regular reflection by 0.5 °. Since an error is actually included, θr−θi = 0.5 ° ± 0.1 °.
Similarly, let R ₃ be the luminance of the

light beams

735 and 736 where θr−θi = −0.5 °. This ray represents a component scattered by the cover member 50 in the direction deviated from the regular reflection by −0.5 °. Since an error is actually included, θr−θi = −0.5 ° ± 0.1 °.

The reflection image diffusivity index value R of the cover member 50 having the antiglare function is calculated by the following equation (3) using the obtained luminances R ₁ , R ₂ , and R ₃ .
Reflected image diffusivity index value R = (R ₂ + R ₃ ) / (2 × R ₁ ) Formula (3)

It has been confirmed that the reflection image diffusiveness index value R has a good correlation with the visual judgment result of the antiglare property by the observer. For example, a cover member 50 having an antiglare function which exhibits a small (close to 0) reflection image diffusion index value R is inferior in antiglare property, and conversely, the reflection image diffusion index value R is large value (close to 1 The cover member 50 having an antiglare function exhibiting a relatively large size) has a good antiglare property.

Such measurement can be performed, for example, by using an apparatus SMS-1000 manufactured by DM & S. When using this device, a C1614A lens with a camera lens focal length of 16 mm is used with a stop 5.6. Further, the distance from the first major surface 52 to the camera lens is about 300 mm, and the imaging scale is set in the range of 0.0276 to 0.0278. The slit opening formed by the black flat plate 712 of the linear light source device 71 is 101 mm × 1 mm.

[Glare index value S]
In the specification of the present application, Anti-Sparkle: S, which is measured by the following procedure, is used as the index of glare.
A method of measuring the glare index value S of the cover member 10 will be described.

When measuring the glare index value S, first, a display device (iPad (registered trademark) -Air; resolution 264 ppi) is prepared. The display surface side of the display device may be provided with a cover for the purpose of preventing damage or the like.

Next, the sample to be measured, that is, the cover member 10 is disposed on the display surface side of the display device. The cover member 10 is disposed on the display surface side of the display device such that the antiglare-treated first main surface 12 is on the opposite side (detector side) of the display device.

Next, with the display device turned on to display an image, an analysis device (SMS-1000; Display-Messtechnik & System [DM & S], Inc.) is used to perform image analysis of the glare degree of the cover member 10. This determines the glare S _a expressed as Sparkle value.

In the measurement, it is preferable that a green single-color image composed of RGB (0, 255, 0) be displayed on the entire display screen of the display device. This is to minimize the influence of differences in appearance due to differences in display colors. The distance d between the fixed imaging device and the cover member 10 is 540 mm. This distance d corresponds to r = 10.8 when represented by the distance index r. Here, the distance index r is expressed by Equation 4 below using the focal length f of the solid-state imaging device and the distance d between the solid-state imaging device and the cover member 10.
Distance index r = (distance between solid-state image sensor and cover member 10) / (focal length f of solid-state image sensor) equation 4

Next, the same measurement is performed on the reference sample. The reference sample is a glass substrate (VRD 140 glass; made by Asahi Glass Europe) having the same thickness as the cover member 10.
Let the obtained Sparkle value be glaring S _s .

From the obtained S _a and S _s, by Equation 5 below, glare index value S of the cover member 10 is calculated.
Glare index value S = 1− (S _a / S _s ) formula 5
This antiglare index value (Anti-Sparkle) S shows a good correlation with the visual judgment result of the observer's visual observation, and it has been confirmed that the antiglare indicator S exhibits a behavior close to human visual sensation. For example, the cover member 10 having a small glare index value S tends to have a noticeable glare, and the cover member 10 having a large glare index value S tends to suppress glare.

In this measurement, it is preferable that a 23 FM 50 SP lens having a focal length of 50 mm be used as the diaphragm 5.6 as a camera lens.

[Visibility index value T]
In the present specification, as an indicator of visibility, a visibility index value (Clarity) T measured in the following procedure is used. Visibility (Clarity) refers to how much an image that matches the displayed image can be obtained when the displayed image is viewed through the glass plate, and is visible (resolved) by the viewer. It has been confirmed that they show good correlation with the judgment results. For example, a glass plate showing a small value (close to 0) of the visibility index value T has poor visibility, and conversely, a glass plate showing a large value of the visibility index value T has good visibility. Therefore, the visibility index value T can be used as a quantitative index in determining the visibility of the glass plate.

The measurement of the visibility index value T is performed according to the following procedure using a variable angle photometer manufactured by Nippon Denshoku Kogyo Co., Ltd., GC5000L. First, when the direction parallel to the thickness direction of the cover member 10 is the angle θ = 0 ° from the resin layer 14 side of the cover member 10, the direction of the angle θ = 0 ° ± 0.5 ° (hereinafter referred to as “ The first light is emitted in the direction of 0 °). The first light passes through the cover member 10, receives the transmitted light from the first major surface 12 on which the antiglare layer is formed, and measures the luminance to obtain “0 ° transmitted light luminance”. Do.
Next, the same operation is performed by changing the angle θ at which light emitted from the first major surface 12 on which the antiglare layer is formed is received in the range of -30 ° to 30 °. Thereby, the brightness distribution of the light which permeate | transmits the cover member 10 and is radiate | emitted from 1st main surface 12 in which the glare-proof layer is formed is measured, it totals, and it is set as "brightness of all the transmitted light."
Next, the visibility index value (Clarity): T is calculated from the following equation 6.
Visibility index value (Clarity) T = 0 degree of luminance of transmitted light / luminance of total transmitted light Formula 6
The visibility index value (Clarity) T has a good correlation with the visual judgment result of the visual resolution of the observer, and it has been confirmed that it exhibits a behavior close to the human visual sense. For example, the cover member 10 in which the visibility index value T shows a small value (close to 0) is inferior in resolution, and conversely, the cover member 10 in which the visibility index value T shows a large value has good resolution. Have. Therefore, the visibility index value T can be used as a quantitative index when determining the resolution of the cover member 10.

Specific examples will be described below by way of examples, but the present invention is not limited to these examples without departing from the spirit of the present invention.

Example 1
In Example 1, the cover member 10 shown in FIG. 1 was produced in the following procedure.

As the transparent substrate 11, soda lime glass (manufactured by Asahi Glass Co., Ltd., size: 100 mm long × 100 mm wide, thickness: 1.1 mm glass substrate) was prepared. The surface of the glass was washed with aqueous sodium hydrogen carbonate, rinsed with ion exchanged water and dried.
The refractive index was measured using a spectral ellipsometer (M-2000 manufactured by J. A. Woollam) to measure the phase difference Δ between s-polarized light and p-polarized light, and the reflection amplitude ratio tanψ. The refractive index was obtained by fitting the refractive index of each layer in the wavelength range of 400 to 700 nm according to Cauchy's dispersion formula. Hereinafter, the measurement of the refractive index of each layer was performed similarly.
Refractive index _{n 1} at the wavelength 550nm of the transparent substrate 11 was 1.52.

The antiglare treatment was performed on the first main surface 12 and the second main surface 13 of the transparent substrate 11 in the following procedure.
The first main surface 12 and the second main surface of the transparent substrate 11 were immersed in a frost treatment solution containing 2 wt% hydrogen fluoride and 3 wt% potassium fluoride for 3 minutes to perform pre-etching treatment. Furthermore, after the transparent substrate was washed, it was immersed in an aqueous solution containing 7.5 wt% hydrogen fluoride and 7.5 wt% hydrogen chloride for 18 minutes (this etching process). Thereby, the first uneven portion and the second uneven portion were formed on the first major surface 12 and the second major surface 13, respectively.

The Rq of the first major surface 12 and the second major surface 13 measured according to the method defined in JIS B0601-2001 was 0.14 μm, and the RSm was 16 μm.

Next, a titanium dioxide (TiO ₂ ) layer (10 nm in thickness) was formed as a high refractive index layer 15 on the second major surface 13 of the transparent substrate 11 by sputtering. The refractive index n ₃ at a wavelength of 550 nm of the titanium dioxide (TiO ₂ ) layer was 2.47.

Next, a 200 μm-thick resin layer 14 is formed on a titanium dioxide (TiO ₂ ) layer using a transparent adhesive sheet LUCIACS (registered trademark) CS986 manufactured by Nitto Denko Corporation, and the cover member shown in FIG. 10 was produced.
Refractive index n ₂ at a wavelength 550nm of the resin layer 14 was 1.5.

Further, the reflection image diffusive index value R of the cover member 10 measured by the above-described procedure was 0.88.
Moreover, the glare index value S of the cover member 10 measured by the above-mentioned procedure was 0.76.
Moreover, the visibility index value T of the cover member 10 measured by the above-mentioned procedure was 0.89.

(Comparative example 1)
A first uneven portion is formed on only the first main surface 12 of the transparent substrate 10 by antiglare treatment, and neither the unevenness nor the high refractive index layer is formed on the second main surface 13. The same procedure as in Example 1 was carried out except using the adhesive sheet LUCIACS (registered trademark) CS986 to form the resin layer 14 with a thickness of 200 μm, to obtain a cover member.
Further, the reflection image diffusiveness index value R of the cover member measured by the above-described procedure was 0.39.
Moreover, the glare index value S of the cover member measured by the above-mentioned procedure was 0.76.
Moreover, the visibility index value T of the cover member measured in the above-mentioned procedure was 0.90.

This application is based on Japanese Patent Application No. 2017-196754 filed on Oct. 10, 2017, the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 cover member 11 transparent base material 12 1st main surface 13 2nd main surface 15 high refractive index layer 14 resin layer 50 cover member 70 measuring apparatus 71 linear light source apparatus 75 surface luminance measuring device 711 light source 712 black flat plate

Claims

A transparent base material comprising a first main surface having a first uneven portion and a second main surface having a second uneven portion;
High refractive index layer; and resin layer,
The high refractive index layer and the resin layer are provided in this order on the second main surface side of the transparent substrate,
A cover satisfying Formula 1 and Formula 2 below, where n 1 is the refractive index of the transparent base, n 2 is the refractive index of the resin layer, and n 3 is the refractive index of the high refractive index layer, at a wavelength of 550 nm. Element.
n 1 <n 3 equation 1
n 2 <n 3 equation 2
The reflectance obtained by subtracting the reflectance at the interface between the first main surface and air from the reflectance of the cover member measured from the first main surface side is 0.1% or more and 4% or less. The cover member as described in.
The refractive index n 2 at a wavelength 550nm of the resin layer is 1.4 to 1.8 and a cover member according to claim 1 or 2.
N 1 -n 2 | | is 0.1 or less, the cover member according to any one of claims 1 to 3, the absolute value of the difference of the refractive index n 1 and the refractive index n 2.
The high refractive index at a wavelength of 550nm in refractive index layer n 3 is 2.0 or more, the cover member according to any one of claims 1 to 4.
The cover member according to any one of claims 1 to 5, wherein the thickness of the high refractive index layer is 5 to 80 nm.
The high refractive index layer is made of titanium dioxide (TiO 2 ), niobium pentoxide (Nb 2 O 5 ), tantalum pentoxide (Ta 2 O 5 ), silicon nitride (Si 3 N 4 ), alumina (Al 2 O 3 ) The cover member according to any one of claims 1 to 6, containing at least one selected from the group consisting of aluminum nitride (AlN), zinc oxide (ZnO), and tin dioxide (SnO 2 ).
The outermost surface of the first uneven portion and the second uneven portion has a surface roughness Rq of 0.02 μm or more and 0.3 μm or less, and an average length RSm of elements of the roughness curve is 8 μm or more and 50 μm or less. Item 8. The cover member according to any one of items 1 to 7.
The cover member according to any one of claims 1 to 8, wherein the first uneven portion and the second uneven portion are formed by an antiglare treatment.
The cover member according to any one of claims 1 to 9, wherein the transparent substrate is made of glass.
The cover member according to any one of claims 1 to 10, wherein the transparent substrate is made of chemically strengthened glass.
The cover member according to any one of claims 1 to 11, wherein the transparent substrate has a bend.