WO2021111813A1

WO2021111813A1 - Optical member and production method therefor

Info

Publication number: WO2021111813A1
Application number: PCT/JP2020/041669
Authority: WO
Inventors: 正章能勢
Original assignee: コニカミノルタ株式会社
Priority date: 2019-12-03
Filing date: 2020-11-09
Publication date: 2021-06-10
Also published as: JP2023007511A

Abstract

The present invention addresses the problem of providing an optical member having an antireflective layer having salt water resistance, photocatalytic effect, and a reduced spectral reflectance in the visible light region, and a production method therefor.　This optical member has a dielectric multilayer film on a substrate, the optical member being characterized in that the dielectric multilayer film at least comprises, from the surface, a low refractive index layer L (1), a high refractive index layer H (2), and an antireflective layer AR, the refractive index of the low refractive index layer L (1) with respect to the helium d-line is less than 1.7, the refractive index of the high refractive index layer H (2) with respect to the helium d-line is 1.7 or higher, at least the low refractive index layer L (1) contains yttrium fluoride (YF3), the high refractive index layer H (2) contains a photocatalytic metal oxide, and the thickness of the high refractive index layer H (2) falls in the range of 200 to 550 nm.

Description

Optical member and its manufacturing method

The present invention relates to an optical member and a method for producing the same, and more particularly to an optical member having a salt water resistance and a photocatalytic effect and having an antireflection layer having a reduced spectral reflectance in the visible light region and a method for producing the same.

A camera is installed in the vehicle to support the driving of the vehicle. More specifically, a camera that captures the rear or side of the vehicle is mounted on the vehicle body, and the image captured by the camera is displayed in a position that can be seen by the driver to reduce the blind spot and drive the vehicle. It contributes to safe driving through support.

By the way, in-vehicle cameras are often mounted outside the vehicle, and there are strict requirements for guaranteeing environmental resistance for the lenses used. _{For example, in a salt spray test on a lens, SiO 2} or MgF _2, which is a component of the antireflection layer on the lens surface, is dissolved in salt water to change the spectral reflectance, which causes ghosts and flares.

Further, in Patent Document 1, since there is a need for an antireflection layer having a self-cleaning property (photocatalytic effect) in an optical system lens used outdoors, a TIO having a film thickness of 200 nm or more is required to obtain the photocatalytic effect. It is disclosed that _{two membranes are required.} However, in the TiO ₂ film a plurality of TiO ₂ film is formed on the thick film, the reduction of the average spectral reflectance would spectral reflectance more than 10 percent of the visible light region is not sufficient.

Therefore, in the salt spray test, the lens surface of the optical member has self-cleaning property and reduced spectral reflectance without any change in spectral reflectance or generation of ghost or flare due to dissolution and peeling of the main component. Appearance is awaited.

Japanese Unexamined Patent Publication No. 2003-287601

The present invention has been made in view of the above problems and situations, and the problems to be solved are an optical member having a salt water resistance and a photocatalytic effect, and an antireflection layer having a reduced spectral reflectance in the visible light region. It is to provide the manufacturing method.

In the process of examining the cause of the above problem in order to solve the above-mentioned problems, the present inventor is an optical member having a dielectric multilayer film on a substrate, which is the uppermost layer of the dielectric multilayer film. The refractive index layer contains a specific compound, the high refractive index layer immediately below the uppermost layer contains a metal oxide having photocatalytic properties, and the thickness of the high refractive index layer is within a specific range. It has been found that an optical member having a salt water resistance and a photocatalytic effect and having an antireflection layer having a reduced spectral reflectance in the visible light region and a method for producing the same can be obtained by the optical member.

That is, the above problem according to the present invention is solved by the following means.

1. 1. An optical member having a dielectric multilayer film on a substrate.
The dielectric multilayer film has at least a low refractive index layer L (1), a high refractive index layer H (2), and an antireflection layer AR from the surface.
The low refractive index layer L (1) has a refractive index of less than 1.7 with respect to the helium d line, and the high refractive index layer H (2) has a refractive index of 1.7 or more with respect to the helium d line.
At least the low refractive index layer L (1) _{contains yttrium fluoride (YF 3} ).
The high refractive index layer H (2) contains a metal oxide having photocatalytic properties, and the thickness of the high refractive index layer H (2) is in the range of 200 to 550 nm. Optical member.
2. An optical member having a dielectric multilayer film on a substrate.
The dielectric multilayer film has at least a low refractive index layer L (1), a high refractive index layer H (2), a low refractive index layer L (3), a high refractive index layer H (4), and an antireflection layer from the surface. It is the composition of AR,
The refractive index of the low refractive index layers L (1) and L (3) with respect to the helium d line is less than 1.7, and the refraction of the high refractive index layers H (2) and H (4) with respect to the helium d line. The rate is 1.7 or higher,
The low refractive index layers L (1) and L (3) _{contain yttrium fluoride (YF 3} ).
The high refractive index layers H (2) and H (4) contain a metal oxide having photocatalytic properties, and the sum of the thicknesses of the high refractive index layers H (2) and H (4) is 200. An optical member having a range of about 550 nm.
3. 3. The optical member according to item 1 or ₂ , wherein the metal oxide is titanium oxide (TiO 2).
4. The optical member according to any one of items 1 to 3, wherein the thickness of the low refractive index layer L (1) is in the range of 60 to 120 nm.
5. The optical member according to any one of items 2 to 4, wherein the thickness of the low refractive index layer L (3) is in the range of 3 to 23 nm.
6. The optical member according to any one of items 1 to 5, wherein the antireflection layer AR has _{a layer containing at least silicon oxide (SiO 2).}
7. Described in any one of items 1 to 6, wherein the spectral reflectance with respect to light incident from the normal direction is 1.5% or less on average in the light wavelength range of 420 to 680 nm. Optical member.
8. A method for manufacturing an optical member according to any one of items 1 to 7, wherein the optical member is manufactured.
A method for manufacturing an optical member, which comprises forming _{the layer containing TiO 2} and the layer containing SiO _{2 by using an ion-assisted deposition method.}

According to the above means of the present invention, it is possible to provide an optical member having a salt water resistance and a photocatalytic effect and having an antireflection layer having a reduced spectral reflectance in the visible light region, and a method for manufacturing the same.

The mechanism of expression or mechanism of action of the effect of the present invention is as follows.

The optical member of the present invention is an optical member having a plurality of antireflection layers on a substrate, and is characterized by containing _{yttrium fluoride (YF 3), which is a low refractive index material, in the uppermost layer.} ..

_{The SiO 2-} containing layer forming the uppermost layer of the conventional dielectric multilayer film _{has a problem in salt water resistance. For example, the SiO 2-} containing layer is 5 nm from the surface due to salt water with respect to the spectral reflectance of the sample before the salt spray test. When dissolved at about 20 nm, the spectral reflectance of the sample at a light wavelength of 550 nm changes remarkably from about 0.5% to about 3.0%. Due to such changes, for example, when the uppermost layer of the antireflection layer (dielectric multilayer film) on the lens is dissolved and peeled off by the external environment (salt water), flare and ghost are generated, which deteriorates from the initial performance. it is conceivable that.

This is because in _{the salt spray test of the SiO 2} containing layer, the pH of the salt water at 25 ° C. is about 7 (weakly alkaline), so that the Si—O bond is easily broken, and the containing layer gradually dissolves in the salt water and peels off. It is presumed that it will be done. Therefore, yttrium is contained as an element in which the activity of oxides and hydroxides is larger than that of ions in the pH range, and by further containing a fluorine atom, the water contact angle of the surface is large and water repellency is exhibited. _{Therefore, yttrium fluoride (YF 3} ), which is a metal fluoride, is calculated to be about 1.3 from the solubility and density in salt water when the layer thickness is the same as _{that of the SiO 2} containing layer in the salt spray test. It is presumed that it has excellent resistance to fluoride water (solubility).

Further, yttrium fluoride (YF ₃ ) has an excellent permeability of the photocatalyst from the lower layer because the filling rate in the film when the film _{is formed is about the same as that of SiO 2.}
As another low refractive index material, MgF ₂ (refractive index 1.385) has a high filling rate in the film, so that the permeability of the photocatalyst from the lower layer is inferior. Further, Al ₂ O ₃ (refractive index 1.620) is also inferior in salt water resistance and permeability of the photocatalyst from the lower layer. On the other hand, YF ₃ is considered to be an excellent material that satisfies the characteristics required as the uppermost layer from the viewpoints of salt water resistance, photocatalytic permeability, and refractive index (reduction of spectral reflectance).

In the present invention, the high refractive index layer H (2) or the high refractive index layers H (2) and H (4) contains a metal oxide having photocatalytic properties, and the high refractive index layer H (2) ), Or the total layer thickness of the high refractive index layers H (2) and H (4) is in the range of 200 to 550 nm.

It is known that the antireflection layer becomes an antireflection layer due to interference when the optical film thickness (refractive index nd / wavelength λ) is 1/4 (0.25) or 1/2 (0.5). ing.

Therefore, if the layer constituting the antireflection layer has a layer thickness larger than 1 / 2λ, interference occurs in the reflected light and the phases do not match well, so that the spectral reflection characteristics deteriorate.

On the other hand, in order to enhance the photocatalytic property, it is effective to thicken the layer containing the metal oxide having the photocatalytic property, but if it is too thick, the spectral reflectance cannot be reduced. Therefore, in order to reduce the spectral reflectance and further effectively exhibit the photocatalytic property, the high refractive index layer H (2) or the high refractive index layer H (2) containing the metal oxide having the photocatalytic property is used. The sum of the thicknesses of H (4) is preferably in the range of 200 to 550 nm, and the sum of the thicknesses of the high refractive index layers H (2) and H (4) is in the range of 200 to 550 nm. As there is, the latter method of dividing into two layers to reduce the thickness per layer is considered to be more effective.

Sectional drawing which shows the structure of the optical member of this invention Sectional drawing which shows another structure of the optical member of this invention Schematic diagram showing an example of an IAD thin-film deposition apparatus Graph measuring the spectral reflectance of an optical member sample Graph measuring the spectral reflectance of an optical member sample Graph measuring the spectral reflectance of an optical member sample Graph measuring the spectral reflectance of an optical member sample Schematic diagram showing a photocatalytic effect evaluation method Schematic diagram showing a photocatalytic effect evaluation method Schematic diagram showing a photocatalytic effect evaluation method

The optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, and the dielectric multilayer film has a low refractive index layer L (1) and a high refractive index layer H (2) at least from the surface. The low refractive index layer L (1) has a refractive index of less than 1.7 with respect to the helium d line, and the high refractive index layer H (2) has the helium d line. The low refractive index layer L (1) _{contains yttrium fluoride (YF 3} ), and the high refractive index layer H (2) is a photocatalytic metal. It is characterized by containing an oxide and having a thickness of the high refractive index layer H (2) in the range of 200 to 550 nm. This feature is a technical feature common to or corresponding to the following embodiments.

Further, the optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, and the dielectric multilayer film has a low refractive index layer L (1) and a high refractive index layer H (1) at least from the surface. 2), low refractive index layer L (3), high refractive index layer H (4), and antireflection layer AR, with respect to the helium d line of the low refractive index layers L (1) and L (3). The refractive index is less than 1.7, the refractive indexes of the high refractive index layers H (2) and H (4) with respect to the helium d line are 1.7 or more, and the low refractive index layers L (1) and L (3) _{contains yttrium fluoride (YF 3} ), and the high refractive index layers H (2) and H (4) contain a metal oxide having photocatalytic properties, and the high refractive index The sum of the thicknesses of the layers H (2) and H (4) is in the range of 200 to 550 nm.

As an embodiment of the present invention, from the viewpoint of exhibiting the effect of the present invention, from the viewpoint that the metal oxide is TiO ₂ has high photocatalytic property and imparts excellent self-cleaning property to the optical member. This is a preferred embodiment.

It is preferable that the thickness of the low refractive index layer L (1) is in the range of 60 to 120 nm from the viewpoint of reducing salt water resistance and spectral transmittance.

It is preferable that the thickness of the low refractive index layer L (3) is in the range of 3 to 23 nm from the viewpoint of further improving salt water resistance by providing two layers containing _{YF 3 as an intermediate layer.} is there.

Further, from the viewpoint of antireflection, it is preferable to have a layer containing _{at least SiO 2} as the antireflection layer inside the optical member as the low refractive index material.

Regarding the spectral reflectance of the optical member of the present invention, the spectral reflectance with respect to light incident from the normal direction is preferably 1.5% or less on average in the light wavelength range of 420 to 680 nm, and more preferably 0.5% on average. The following is more preferable from the viewpoint of improving the visibility of the image captured as the in-vehicle lens.

In the method for manufacturing an optical member of the present invention, _{the layer containing TiO 2} and the layer containing SiO ₂ are subjected to an ion-assisted deposition method (“IAD vacuum deposition method” or simply “IAD”. Forming using the method (also referred to as “method”) is a preferable method for producing an optical member from the viewpoint of being able to form a denser film and further improving salt water resistance.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "-" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

<< Outline of the Optical Member of the Present Invention >>
The optical member of the present invention is an optical member having a dielectric multilayer film on a substrate, and the dielectric multilayer film has a low refractive index layer L (1) and a high refractive index layer H (2) at least from the surface. The low refractive index layer L (1) has a refractive index of less than 1.7 with respect to the helium d line, and the high refractive index layer H (2) has the helium d line. The low refractive index layer L (1) contains yttrium fluoride (hereinafter, may be referred to as _{“YF 3} ”), and the high refractive index layer L (1) has a refractive index of 1.7 or more. H (2) contains a photocatalytic metal oxide, and the thickness of the high refractive index layer H (2) is in the range of 200 to 550 nm.

Above all, the sum of the thicknesses of the high refractive index layers H (2) and H (4) is preferably in the range of 200 to 290 nm from the viewpoint of developing photocatalytic property and reducing spectral reflectance.

FIG. 1 is a cross-sectional view showing the configuration of the optical member of the present invention.

FIG. 1A is a cross-sectional view showing the optical member 100 according to the first embodiment.

The dielectric multilayer film 115 having an antireflection function is, for example, the high refractive index layers 103 and 105 having a refractive index higher than the refractive index of the glass substrate 101 constituting the lens, and lower than the high refractive index layer. It contains an antireflection layer AR107 composed of low refractive index layers 102, 104 and 106 having a refractive index, and a high refractive index layer H (2) 108 and YF _{3 which are layers containing a metal oxide having a photocatalytic property.} It has a low refractive index layer L (1) which is the uppermost layer.

The antireflection layer AR according to the present invention preferably has a multilayer structure in which the high refractive index layer and the low refractive index layer are alternately laminated. The optical member of the present invention has a spectral reflectance of preferably 1.5% or less with respect to light incident from the normal direction in a light wavelength range of 420 to 680 nm, as an in-vehicle lens. This is preferable from the viewpoint of improving the visibility of the captured image. Further, the spectral reflectance is more preferably 0.5% or less on average.

For the average spectral reflectance, for example, in the optical wavelength range of 380 to 780 nm, the spectral reflectance with respect to light incident from the normal direction is measured using a visible differential light measuring machine USPM-RU III manufactured by Olympus. The spectral reflectance values in the visible light wavelength range of 420 to 680 nm can be appropriately extracted and averaged to obtain the average spectral reflectance.

The uppermost layer 109 according to the present invention is a metal fluoride layer containing _{YF 3 as a main component.} The refractive index of the uppermost layer with respect to the helium d-line (light wavelength 587.56 nm) is less than 1.7, which is a preferable range of the refractive index from the viewpoint of reducing the spectral reflectance.

The layer directly below the uppermost layer according to the present invention refers to the high refractive index layer H (2) 108, which is a layer containing a photocatalytic metal oxide in FIG. 1A. The refractive index of the high refractive index layer H (2) 108 with respect to the helium d line (light wavelength 587.56 nm) is 1.7 or more, which is a preferable range of the refractive index from the viewpoint of reducing the spectral reflectance. ..

FIG. 1B is a cross-sectional view showing the optical member 100 according to the second embodiment.

The dielectric multilayer film 115 having an antireflection function is, for example, the high refractive index layers 103 and 105 having a refractive index higher than the refractive index of the glass substrate 101 constituting the lens, and lower than the high refractive index layer. High refractive index layers H (2) 108 and H (4), which are layers containing a low

refractive index layer

102, 104, 106 having a refractive index and an antireflection layer AR107 and a metal oxide having a photocatalytic property. It has 110, a low refractive index layer L (1) which is the uppermost layer containing _{YF 3, and L (3) 111 which is an intermediate layer.} The low refractive index layer L (3) may be hereinafter referred to as an “intermediate layer”.

As described above, if the layer constituting the antireflection layer has a layer thickness significantly larger than 1 / 2λ, interference occurs in the reflected light and the phases do not match well, so that the spectral reflection characteristics deteriorate. On the other hand, in order to enhance the photocatalytic property, it is effective to thicken the layer containing the metal oxide having the photocatalytic property, but if it is thickened, the spectral reflectance cannot be reduced. Therefore, in order to reduce the spectral reflectance and further effectively exhibit the photocatalytic property, as shown in FIG. 1B, the high refractive index layers H (2) and H (4) containing the metal oxide having the photocatalytic property. ), It is effective to design the layer so that the total layer thickness is in the range of 200 to 550 nm.

The optical member of the present invention shown in FIG. 1 is formed by laminating a low refractive index layer, a high refractive index layer, an uppermost layer 109 according to the present invention, and a layer immediately below it on a substrate 101 to form a dielectric multilayer film. However, the uppermost layer and the layer immediately below the uppermost layer according to the present invention may be formed on both sides of the substrate 101. That is, it is preferable that the uppermost layer and the layer immediately below the uppermost layer according to the present invention are on the side exposed to the external environment, but not on the exposed side, for example, on the inner side opposite to the exposed side. In order to prevent the influence of internal environmental changes, the uppermost layer according to the present invention and the layer immediately below the upper layer may be formed. In addition to the lens, the optical member of the present invention can also be applied to an optical member such as an antireflection member or a heat shield member.

[1] Structure and manufacturing method of dielectric multilayer film [1.1] Structure and manufacturing method of low refractive index layers L (1) and L (3) The low refractive index layers L (1) and L according to the present invention. (3) is a _{layer containing YF 3} as a main component, and the “main component” means that the YF ₃ contained in the layer is preferably 90% by mass or more, preferably 95% by mass or more. It is more preferable, and particularly preferably, it is contained in an amount of 98% by mass or more.

The refractive index of the low refractive index layer L (1) with respect to the light wavelength of 587.56 nm (d line) is less than 1.7, which is a preferable range of the refractive index from the viewpoint of reducing the spectral reflectance. A more preferable refractive index is in the range of 1.45 to 1.55.

The thickness of the low refractive index layer L (1) is preferably in the range of 60 to 120 nm from the viewpoint of salt water resistance and reduction of spectral reflectance, and similarly, the low refractive index layer L which is an intermediate layer. The thickness of (3) is preferably in the range of 3 to 23 nm.

As a preferable method for forming the low refractive index layers L (1) and L (3) of the present invention, in order to ensure high productivity, a vacuum deposition method is used for the vapor deposition system, a sputtering method, a magnetron sputtering method, etc. are used for the sputtering system. It is preferable to utilize it. In the film formation of metal fluoride, it is preferable not to use the IAD method or the like because the metal fluoride is decomposed by ion irradiation.

When the vacuum deposition method is adopted as the film forming condition, the degree of decompression in the chamber is usually in the range of 1 × 10 ^-4 to 1 × 10 ^-1 Pa, preferably 1 × 10 ^-3 to 1 × 10 ^-2 Pa. The film formation rate is within the range of 1 to 10 Å / sec, specifically, using BES-1300 manufactured by Syncron, for example, a heating temperature of 340 ° C., a starting vacuum degree of 1.33 × 10 ^-3 Pa, and film formation. It is preferable to form a film at a rate of 7 Å / sec. Further, the same _{applies to the case where the SiO 2-} containing layer and the MgF _2- containing layer are formed without using the IAD method.

[1.2] Configuration and Manufacturing Method of Antireflection Layer AR, High Refractive Index Layers H (2) and H [4] As described above, the dielectric multilayer film having an antireflection function has a higher refractive index than the substrate. It has a high refractive index layer having a refractive index and a low refractive index layer having a refractive index lower than that of the high refractive index layer. It is preferable to have a multilayer structure in which these high refractive index layers and low refractive index layers are alternately laminated. The number of layers is not particularly limited, but it is preferable that the number of layers is 12 or less from the viewpoint of maintaining high productivity and obtaining an antireflection layer. That is, the number of layers depends on the required optical performance, but the reflectance of the entire visible light region can be reduced by laminating about 3 to 8 layers, and the upper limit is 12 layers or less. This is preferable in that it is possible to prevent the film from being peeled off due to an increase in stress of the film.

The refractive index of the high refractive index layer with respect to the light wavelength of 587.56 nm is in the range of 1.9 to 2.45, and the refractive index of the low refractive index layer with respect to the light wavelength of 587.56 nm is 1.3 to 1.5. It is preferably within the range of.

The material used for the antireflection layer AR of the dielectric multilayer film (high refractive index layer, low refractive index layer) according to the present invention is preferably, for example, Ti, Ta, Nb, Zr, Ce, La, Al, Oxides such as Si and Hf, or oxidation compounds combining these, and MgF ₂ are suitable. Further, by stacking a plurality of layers of different dielectric materials, it is possible to add a function of reducing the reflectance of the entire visible light region.

The low refractive index layer is made of a material having a refractive index lower than that of the substrate, and in the present invention, it is preferably _{SiO 2} or _{a mixture of SiO 2} and Al ₂ O _3. In particular, _{a layer containing SiO 2} is preferable from the viewpoint of reducing the spectral reflectance.

The high refractive index layer is composed of a material having a higher refractive index than that of the substrate. For example, a mixture of Ta oxide and Ti oxide, Ti oxide, Ta oxide, and La oxide. It is preferably a mixture of oxides of and Ti. In the present invention, _{it is preferably Ta 2} O ₅ or TiO ₂ , and more preferably Ta ₂ O ₅ .

In the optical member of the present invention, the high-refractive index layer H (2) or _{the layers containing TiO 2} in the high-refractive index layers H (2) and H (4) are used as a photocatalytic layer having a self-cleaning function. Use. The self-cleaning function of TiO ₂ refers to the effect of photocatalyst on organic matter decomposition. This is because when TiO ₂ is irradiated with ultraviolet light, OH radicals are generated after electrons are emitted, and organic substances are decomposed by the strong oxidizing power of the OH radicals. _{By adding the TiO 2} containing layer to the optical member of the present invention, it is possible to prevent organic substances and the like adhering to the optical member from contaminating the optical system as dirt. In that case, it is preferable that the upper YF _3- containing layer has a slightly coarse film quality because OH radicals can easily move and the antifouling property on the surface of the optical member can be improved.

As described above, the sum of the thicknesses of the high refractive index layer H (2) or the high refractive index layers H (2) and H (4) is preferably in the range of 200 to 550 nm, and the high refractive index is preferably in the range of 200 to 550 nm. The latter method of reducing the metal oxide content per layer by dividing into two layers so that the sum of the thicknesses of the rate layers H (2) and H (4) is in the range of 200 to 550 nm is available. It is more effective.

The thickness of the dielectric multilayer film (the total thickness when a plurality of layers are laminated) is preferably in the range of 50 nm to 5 μm. When the thickness is 50 nm or more, the optical characteristics of antireflection can be exhibited, and when the thickness is 5 μm or less, surface deformation due to the film stress of the multilayer film itself can be prevented. It is preferably in the range of 100 nm to 1 μm.

As a method for forming a thin film such as a metal oxide on a substrate, a reactive sputtering method such as a sputtering method for an inorganic material (for example, magnetron cathode sputtering, flat plate magnetron sputtering, 2-pole AC flat plate magnetron sputtering, 2-pole AC rotating magnetron sputtering, etc.) Includes), vapor deposition methods (eg, resistance heating vapor deposition, electron beam deposition, ion beam deposition, plasma-assisted vapor deposition, and vacuum vapor deposition using the IAD method), thermal CVD method, catalytic chemical vapor deposition method (Cat-CVD). ), Capacitive bonded plasma CVD method (CCP-CVD), optical CVD method, plasma CVD method (PE-CVD), epitaxial growth method, chemical vapor deposition method such as atomic layer growth method, or the like.

In the present invention, it is preferable that the vacuum deposition method (IAD method) uses the IAD method.

The IAD method is a method in which the high kinetic energy of ions is applied during film formation to form a dense film or to increase the adhesion of the film. For example, the ion beam method is an ionization method irradiated from an ion source. This is a method of accelerating the adherend material with the generated gas molecules to form a film on the surface of the substrate. The IAD method is also referred to as an "ion beam assist method".

FIG. 2 is a schematic view showing an example of a vacuum deposition apparatus using the IAD method.

The vacuum vapor deposition apparatus 1 using the IAD method (hereinafter, also referred to as an IAD vapor deposition apparatus in the present invention) includes a dome 3 in the chamber 2, and the substrate 4 is arranged along the dome 3. The thin-film deposition source 5 includes an electron gun or a resistance heating device that evaporates the vapor-deposited substance, and the thin-film deposition material 6 scatters from the vapor deposition source 5 toward the substrate 4 and condenses and solidifies on the substrate 4. At that time, the ion beam 8 is irradiated from the IAD ion source 7 toward the substrate, and the high kinetic energy of the ions is applied during the film formation to form a dense film or enhance the adhesion of the film.

Here, as an example of the substrate 4, glass can be mentioned.

A plurality of thin-film deposition sources 5 may be arranged at the bottom of the chamber 2. Here, one vapor deposition source is shown as the vapor deposition source 5, but the number of the vapor deposition sources 5 may be plural. The film-forming material (deposited material) of the vapor deposition source 5 is generated by an electron gun to generate the vapor-deposited substance 6, and the film-forming material is scattered and adhered to the substrate 4 (for example, a glass plate) installed in the chamber 2. A layer made of a material (for example, a low refractive index material of the antireflection layer AR, SiO ₂ , MgF ₂ , or Al ₂ O ₃ layer, or a high refractive index material such as _{Ta 2} O ₅ or TiO ₂₎ A film is formed on the substrate 4. Further, it is preferable to use a vacuum deposition method using the same IAD method for the high refractive index layers H (2) and H (4) according to the present invention.

Further, the chamber 2 is provided with a vacuum exhaust system (not shown), whereby the inside of the chamber 2 is evacuated. The degree of decompression in the chamber is usually in the range of 1 × 10 ^-4 to 1 × 10 ^-1 Pa, preferably 1 × 10 ^-3 to 1 × 10 ⁻² Pa.

The dome 3 holds at least one holder (not shown) for holding the substrate 4, and is also called a vapor deposition umbrella. The dome 3 has an arcuate cross section, passes through the center of a string connecting both ends of the arc, and has a rotationally symmetric shape that rotates with an axis perpendicular to the string as a rotationally symmetric axis. As the dome 3 rotates about the shaft at a constant speed, for example, the substrate 4 held by the dome 3 via the holder revolves around the shaft at a constant speed.

The dome 3 can hold a plurality of holders side by side in the radial direction of rotation (radial direction of revolution) and the direction of rotation (revolutionary direction). As a result, it is possible to simultaneously form a film on a plurality of substrates 4 held by a plurality of holders, and it is possible to improve the manufacturing efficiency of the device.

The IAD ion source 7 is a device that introduces argon or oxygen gas into the main body to ionize them and irradiates the ionized gas molecules (ion beam 8) toward the substrate 4. As the ion source, Kaufmann type (filament), hollow cathode type, RF type, bucket type, duoplasmatron type and the like can be applied. By irradiating the substrate 4 with the above gas molecules from the IAD ion source 7, for example, the molecules of the film-forming material evaporating from a plurality of evaporation sources can be pressed against the substrate 4, and a film having high adhesion and density can be formed on the substrate. A film can be formed on the 4. Although the IAD ion source 7 is installed at the bottom of the chamber 2 so as to face the substrate 4, it may be installed at a position deviated from the facing axis.

The ion beam used in the IAD method is used at a lower vacuum degree than the ion beam used in the ion beam sputtering method, and tends to have a lower acceleration voltage. For example, an ion beam having an acceleration voltage of 100 to 2000 V, an ion beam having a current density of 1 to 120 μA / cm ² , or an ion beam having an acceleration voltage of 500 to 1500 V and a current density of 1 to 120 μA / cm ² can be used. In the film forming step, the irradiation time of the ion beam can be set to, for example, 1 to 800 seconds, and the number of particles irradiated by the ion beam can be set, for example, 1 × 10 ¹³ to 5 × 10 ¹⁷ particles / cm ² . The ion beam used in the film forming step can be an oxygen ion beam, an argon ion beam, or an ion beam of a mixed gas of oxygen and argon. For example, it is preferable that the oxygen introduction amount is within the range of 30 to 60 sccm and the argon introduction amount is within the range of 0 to 10 sccm. "Sccm" is an abbreviation for standard cc / min, and is a unit indicating how many cc flowed per minute at 1 atm (atmospheric pressure 1013 hPa) and 0 ° C.

The monitor system (not shown) is a system that monitors the wavelength characteristics of the layer formed on the substrate 4 by monitoring the layer that evaporates from each vapor deposition source 5 and adheres to itself during vacuum film formation. .. With this monitor system, it is possible to grasp the optical characteristics (for example, spectral transmittance, spectral reflectance, optical layer thickness, etc.) of the layer formed on the substrate 4. The monitor system also includes a crystal layer thickness monitor, and can monitor the physical layer thickness of the layer formed on the substrate 4. This monitor system also functions as a control unit that controls ON / OFF switching of a plurality of evaporation sources 5 and ON / OFF switching of the IAD ion source 7 according to the monitoring result of the layer.

[1.3] Base material As the base material according to the present invention, specifically, glass is preferably applied, and glass used for ordinary optical lenses is preferable. As the glass, for example, glass such as quartz, borosilicate glass, or chemically tempered glass is preferably used.

The thickness of the base material according to the present invention (in the case of a laminated structure of two or more layers, the total thickness thereof) is preferably 10 to 200 μm, more preferably 20 to 150 μm.

[2] In-vehicle or outdoor optical member Examples of the optical member of the present invention include an in-vehicle or outdoor optical lens, and in particular, a lens for an in-vehicle camera (a lens constituting a lens unit). preferable.

An "in-vehicle camera" is a camera installed on the outside of the vehicle body, which is installed at the rear part of the vehicle body and used for rear confirmation, or installed at the front part of the vehicle body for front confirmation. Alternatively, it is used for checking the side or for checking the distance to the vehicle in front.

Such a lens unit for an in-vehicle camera is composed of a plurality of lenses, and more specifically, is composed of an object-side lens arranged on the object side and an image-side lens group arranged on the image side. The image-side lens group includes a plurality of lenses and a diaphragm provided between the lenses.

Among such a plurality of lenses, the lens on the object side has an exposed surface exposed to the outside air, and the optical member of the present invention is used as the lens having this exposed surface.

Further, examples of application of the optical member include an outdoor installation type surveillance camera, and among the lenses constituting the surveillance camera, the optical member of the present invention is used as lenses having an exposed surface exposed to the outside air. Be done.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

<Preparation of optical member sample>
Using the IAD vapor deposition apparatus shown in FIG. 2, vapor deposition by the IAD method was performed under the following conditions (the notation (IAD) after the film forming material indicates that the IAD method was used).

For the film formation without IAD, the film deposition was performed using only the vapor deposition source 5 in FIG. Table I summarizes the film forming conditions and the refractive index of the film forming material on the d line.

The film forming materials used in the examples are as follows.

<Film film material>
YF ₃ : Merck product name YF ₃
SiO ₂ : Merck product name SiO ₂
OA600: Made by Canon Optron Product name OA600 Ta ₂ O ₅ , TiO, Ti ₂ O ₅ mixture TiO ₂ : Made by Fuji Titanium Product name Ti ₃ O ₅
MgF ₂ : Merck product name MgF ₂
<substrate>
TAF1: Made by HOYA <Formation of dielectric multilayer film>
(Conditions in the chamber)
Heating temperature 340 ° C
Starting vacuum degree 3.0 × 10 ^-3 Pa
(Evaporation source of film-forming material)
Electron gun

<Optical member No. Preparation of 1>
(Anti-reflection layer AR: film formation of low refractive index layer and high refractive index layer)
Film formation material for low refractive index layer: SiO ₂
The above-mentioned base material is installed in a vacuum vapor deposition apparatus, the film-forming material is loaded into the first evaporation source, vapor deposition is carried out at a film-forming rate of 4 Å / sec, and a low refractive index with a thickness of 36.7 nm is formed on the base material. A layer was formed.

The low refractive index layer is formed by the IAD method, with an acceleration voltage of 1000 V, an acceleration current of 1000 mA, and a neutralization (bias) current of 1200 mA. Using. Amount of gas introduced during film formation by vapor deposition is a 2 × 10 ^-2 PA, IAD introduced gas was carried out by O ₂ 50 sccm, Ar gas 0 sccm, the neutral gas O ₂ 50 sccm conditions.

High refractive index layer film forming material: A600
The above-mentioned base material is installed in a vacuum vapor deposition apparatus, the film-forming material is loaded into the second evaporation source, vapor deposition is carried out at a film-forming rate of 2.0 Å / sec, and the thickness is 11. A high refractive index layer of 0 nm was formed. The formation of the high refractive index layer was similarly carried out by the IAD method.

A low refractive index layer and a high refractive index layer were laminated and formed on the formed high refractive index layer under the layer thickness conditions shown in Table II to prepare a total of five dielectric multilayer films.

(Photocatalyst layer: High refractive index layer H (2) or film formation of high refractive index layers H (2) and H (4))
Photocatalyst layer film forming material: TiO ₂
The film-forming material was loaded into the third evaporation source on the substrate on which the film was formed up to the above five layers, and the film was deposited at a film-forming rate of 2.0 Å / sec, and the thickness was 129.3 nm on the low refractive index layer. The photocatalyst layer H (4) was formed. The photocatalyst layer was similarly formed by the IAD method at an acceleration voltage of 500 V, an acceleration current of 500 mA, and a neutralization (bias) current of 750 mA.

Similarly, a high refractive index layer H (2) having a photocatalytic property of 121.0 nm was formed.

(Top layer: film formation of low refractive index layer L (1) and intermediate layer L (3))
Top layer and intermediate layer film forming material: YF ₃
The film-forming material is loaded into the fourth evaporation source on the base material on which the lower layer is formed, and the film is deposited at a film-forming rate of 4.0 Å / sec, and the uppermost layer having a thickness of 80.6 nm is deposited on the photocatalyst layer. The low refractive index layer L (1) was formed, and the intermediate layer L (3) having a thickness of 11.7 nm was formed in the same manner.

<Optical member sample No. 2-No. Preparation of 16>
Optical member sample No. In the same manner as in the production of No. 1, a dielectric multilayer film having the layer structure and layer thickness of Tables II and III was formed, and the optical member sample No. 2-No. 16 was made.

_{For the optical member using SiO 2} and MgF ₂ as the low refractive index materials, thin-film deposition was performed at a film formation rate of 2.2 Å / sec and 4.0 Å / sec, respectively, using an electron gun.

≪Evaluation≫
The obtained optical member sample No. 1 to No. The following evaluation was carried out using 16.

(1) Measurement of spectral reflectance In the light wavelength range of 380 to 780 nm, the spectral reflectance for light incident from the normal direction is measured and visible using the USPM-RU III microscopic differential light measuring machine manufactured by Olympus. The spectral reflectance values for each 10 nm in the light region (420 to 680 nm) were extracted and averaged to obtain the average spectral reflectance.

The measurement results are shown in FIGS. 3 to 6. Ranks were performed based on the shape of the spectral reflectance. The above is acceptable, but it is preferably 〇 to ◎.
⊚: The average spectral reflectance in the visible light region is 0.5% or less, which is excellent: FIG.
〇: Although the spectral reflectance in the visible light region is slightly disturbed, the average spectral reflectance is 1.0% or less, which is not a problem: Fig. 4
Δ: Although the spectral reflectance in the visible light region is disturbed, the average spectral reflectance is 1.5% or less, and there is no practical problem: FIG.
X: There is a large disturbance in the spectral reflectance in the visible light region, and the average spectral reflectance exceeds 1.5%, which is a practical problem: Fig. 6

(2) Salt spray test The following evaluation was performed using the obtained optical member sample.

<Salt spray test>
Eight cycles were carried out, with the following (a) to (c) as one cycle.
(A) At the temperature inside the spray layer of 35 ± 2 ° C., the solvent of 25 ± 2 ° C. is sprayed on the uppermost layer side of the optical member sample for 2 hours.
(B) After spraying is completed, the mixture is left at 40 ± 2 ° C. and 95% RH for 22 hours.
(C) After repeating (a) and (b) four times, the mixture is left at 25 ° C. and 55% RH for 72 hours.
<solvent>
Solutes used: NaCl, MgCl ₂ , CaCl ₂
Solute concentration: 5 ± 1% by mass

<Measurement of spectral reflectance>
The spectral reflectance of the optical member sample before and after the salt spray test was measured, and if the average value of the spectral reflectance in the light wavelength range of 420 to 680 nm fluctuated within 0.1%, it was evaluated as 〇 and 0. The case where the fluctuation exceeds 0.1% and is within 0.15% is marked with Δ, and the case where the fluctuation exceeds 0.15% is marked with ×. △ The above was regarded as a pass.

(3) Photocatalytic effect evaluation method The following evaluation was performed using the obtained optical member sample.

(A) A schematic diagram of the lighting device 200 for evaluating the lighting arrangement is shown in FIG. 7A.

Install the UV light 202 in the black housing 201.

The marker surface 205 on the uppermost layer side of the produced optical member sample 204 is on the UV light 202 side, and the sample is placed on the flat plate 203.

Adjust the height so that the distance between the UV light 202 and the optical member sample 204 is 30 mm.

(B) How to apply the pen Draw a line on the photocatalyst surface with the The Visualizer pen manufactured by Ink intensity.

From the image of drawing a line, the image of dropping ink (Fig. 7B206) in dots is used.

Ink is applied in 1 step with about 5 points x 2 steps.

(C) UV light irradiation When the outlet of the UV light (BL20 manufactured by YAZAWA) is plugged in, the lamp lights up.

At a height of 30 mm, irradiate UV light with an integrated light intensity of 10 J for 1 hour.

Check the color change after 1 hour and 2 hours.

(D) Color evaluation Since the color tone is not stable immediately after taking out, the color change at each time is evaluated after 30 minutes or more have passed after taking out (FIG. 7B). If there is a photocatalytic effect, the color change will change from blue to transparent (photocatalytic effect "yes").
The evaluation ranks are as follows, and 〇 or higher is a pass.
⊚: Color change 5 in FIG. 7C and photocatalytic effect is particularly excellent 〇: Color change 4 in FIG. 7C and photocatalytic effect is excellent Δ: Color change 3 in FIG. 7C and photocatalytic effect is slightly inferior ×: It is the color change 2 of FIG. 7C, and the photocatalytic effect is inferior, which is a problem.

(4) Measurement of contact angle with water Using the obtained optical member sample, the contact angle with water in the uppermost layer was determined.

The contact angle with water is as follows: After leaving the sample for 24 hours in an atmosphere with a temperature of 23 ° C and a relative humidity of 55%, a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product) in an atmosphere with a temperature of 23 ° C and a relative humidity of 55%. Using the name DropMaster DM100), the contact angle of pure water 1 minute after dropping 1 μl of pure water was measured. It should be noted that the measurement is performed 7 times, and the value is the average of 5 measured values excluding the maximum value and the minimum value of the measured values.
In order for the uppermost layer to exhibit hydrophilicity, the contact angle is preferably 30 ° or less.

(5) Comprehensive evaluation As a comprehensive evaluation of the spectral reflectance, the salt spray test, and the photocatalytic effect, an optical member having at least one performance of failure level × and an optical member having two or more evaluation levels Δ were used as comparative examples.

Although the optical member having one evaluation level Δ is in the present invention, the overall evaluation is Δ, and the optical member having only the better evaluation level 〇 or ◎ is rated as ◯, and the ranking is performed.

Table II and Table III below show the configuration, manufacturing method, and evaluation results of the optical member sample.

From Table II and Table III, No. 1 which is an optical member sample having the constitution of the present invention. Compared to the comparative examples, 1, 2, 6, 7, 9 to 13, and 15 are excellent in spectral reflectance and salt water resistance, and further, because a TiO ₂ containing layer is provided in the optical member as a photocatalyst layer, It can be seen that it exhibits a photocatalytic effect and is also excellent in self-cleaning property.

On the other hand, the _{optical member 4 having SiO 2} in the uppermost layer was inferior in salt water resistance, _{and the optical member 5 using MgF 2} in the intermediate layer L (3) was inferior in photocatalytic property.

The optical member of the present invention is an optical member having salt water resistance and a photocatalytic effect and having an antireflection layer having a reduced spectral reflectance in the visible light region, and is used in the outside air for in-vehicle use or outdoor use (surveillance camera, etc.). It is preferably used for an optical lens on the exposed surface side to be exposed.

1 IAD vapor deposition equipment 2 chamber 3 dome 4 substrate 5 vapor deposition source 6 vapor deposition material 7 IAD ion source 8 ion beam 100 optical member dielectric multilayer film 101 substrate 102 low refractive index layer 103 high refractive index layer 104 low refractive index layer 105 high refractive index Rate layer 106 Low refractive index layer 107 Antireflection layer AR
108 High refractive index layer H (2)
109 Low refractive index layer L (1)
110 High refractive index layer H (4)
111 Low refractive index layer L (3)
115 Dielectric multilayer film 200 Photocatalyst evaluation device 201 Black housing 202 UV lamp 203 Flat plate 204 Optical member sample 205 Marker surface 206 Ink

Claims

An optical member having a dielectric multilayer film on a substrate.
The dielectric multilayer film has at least a low refractive index layer L (1), a high refractive index layer H (2), and an antireflection layer AR from the surface.
The low refractive index layer L (1) has a refractive index of less than 1.7 with respect to the helium d line, and the high refractive index layer H (2) has a refractive index of 1.7 or more with respect to the helium d line.
At least the low refractive index layer L (1) contains yttrium fluoride (YF 3 ).
The high refractive index layer H (2) contains a metal oxide having photocatalytic properties, and the thickness of the high refractive index layer H (2) is in the range of 200 to 550 nm. Optical member.
An optical member having a dielectric multilayer film on a substrate.
The dielectric multilayer film has at least a low refractive index layer L (1), a high refractive index layer H (2), a low refractive index layer L (3), a high refractive index layer H (4), and an antireflection layer from the surface. It is the composition of AR,
The refractive index of the low refractive index layers L (1) and L (3) with respect to the helium d line is less than 1.7, and the refraction of the high refractive index layers H (2) and H (4) with respect to the helium d line. The rate is 1.7 or higher,
The low refractive index layers L (1) and L (3) contain yttrium fluoride (YF 3 ).
The high refractive index layers H (2) and H (4) contain a metal oxide having photocatalytic properties, and the sum of the thicknesses of the high refractive index layers H (2) and H (4) is 200. An optical member having a range of about 550 nm.
The optical member according to claim 1 or 2 , wherein the metal oxide is titanium oxide (TiO 2).
The optical member according to any one of claims 1 to 3, wherein the thickness of the low refractive index layer L (1) is in the range of 60 to 120 nm.
The optical member according to any one of claims 2 to 4, wherein the thickness of the low refractive index layer L (3) is in the range of 3 to 23 nm.
The optical member according to any one of claims 1 to 5, wherein the antireflection layer AR has a layer containing at least silicon oxide (SiO 2).
The invention according to any one of claims 1 to 6, wherein the spectral reflectance with respect to light incident from the normal direction is 1.5% or less on average in the light wavelength range of 420 to 680 nm. Optical member.
A method for manufacturing an optical member according to any one of claims 1 to 7, wherein the optical member is manufactured.
A method for manufacturing an optical member, which comprises forming the layer containing TiO 2 and the layer containing SiO 2 by using an ion-assisted deposition method.