JP6513486B2 - Antifogging antireflective film, cover substrate with antifogging antireflective film, and method for producing antifogging antireflective film - Google Patents

Description

  The present invention relates to an antifogging antireflective film having antifogging properties and antireflective ability, a cover substrate with an antifogging antireflective film, and a method for producing the antifogging antireflective film.

  A camera installed outdoors, a lidar (LIDAR: Light Detection and Ranging or Laser Imaging Detection and Ranging), and instruments are required to have a good visual field from the inside and a good visibility from the outside. Usually, in the optical system of these devices, a front window made of a transparent base material is installed to transmit light in and out of the device, and in order to maintain a good visual field and visibility, it is necessary to In this case, it is necessary that the surface of the front window is not fogged by raindrops, dew condensation or the like, that is, anti-fogging property.

The addition of an antifogging property to a transparent substrate such as glass is generally performed by modifying the surface of the substrate to a superhydrophilic property in which the contact angle of water droplets is 10 ° or less.
A method of forming an oxide such as Ti, Ta, Nb, or Zr having a photocatalytic function on a substrate to have hydrophilicity, or including photocatalytic particles, an oxide having a photocatalytic function on a substrate, a photocatalytic function Many methods of forming a mixture layer of particles and forming a SiO ₂ film or the like as a hydrophilic layer thereon are disclosed.
For example, as a method of modifying the surface to be superhydrophilic, Non-Patent Document 1 describes that superhydrophilicity is expressed by roughening the hydrophilic surface.
However, when superhydrophilicity is imparted by roughening the surface, organic compounds in the air, nitrogen compounds, etc. adhere to the surface due to long-term exposure to the environment, and the superhydrophilicity decreases and the antifogging properties It was lost.

  With respect to this problem, Patent Document 1 describes a method of forming a photocatalytic film containing a photocatalytic semiconductor material and silica on a substrate. Further, Patent Document 2 describes a method of forming a transparent photocatalyst film exhibiting photocatalytic reaction on the surface of a substrate member, and forming a transparent and porous inorganic oxide film on the outermost surface of the film. It is done. According to the methods of Patent Documents 1 and 2, even if organic compounds, nitrogen compounds, etc. adhere to the surface, they are decomposed and removed by the photocatalytic reaction of the photocatalyst film, so superhydrophilicity is maintained and antifogging Sex continues.

  As well known, a titanium oxide thin film is generally used for the photocatalytic film. Titanium oxide has a refractive index of 2.2 to 2.4, and has a higher refractive index than transparent substrates such as glass. Therefore, when titanium oxide is formed on the transparent substrate, the reflectance is increased, and a part of incident light is reflected to cause flare or ghost in a camera image. In addition, the amount of transmitted light entering the camera is reduced. It also causes glare and glare on the surface.

To address this problem, Patent Document 3 describes an antireflective film having a structure in which high refractive index layers and low refractive index layers are alternately stacked and the final layer is titanium oxide. Patent Document 4 discloses a reflection of a structure comprising a low refractive index layer made of a non-hydrophilic inorganic compound such as fluoride and a high refractive index layer made of titanium oxide provided in the lower layer of the low refractive index layer. A protective film is described. Furthermore, Patent Document 5 describes an antireflective film having a structure in which the uppermost layer is a hydrophilic low refractive index layer, and the high refractive index layer provided below the low refractive index layer is titanium oxide. There is.
As described above, Patent Documents 3 to 5 describe antireflective films having superhydrophilicity and antifogging properties by photocatalytic reaction.

R. N. Wenzel, “Resistance of solid surfaces to wetting by water”, Ind. Eng. Chem., 28, 988-94 (1936).

Patent No. 2756474 Patent No. 2901550 Japanese Patent Publication No. 2004-510051 JP, 2005-165014, A JP, 2008-3390, A

In order to decompose and remove organic compounds, nitrogen compounds and the like attached to the surface by the photocatalyst film exhibiting photocatalytic reaction and to ensure the purification of the front window surface and the antifogging property by the self-cleaning effect, the catalyst besides the conventional optical design It is necessary to further promote reactivity and hydrophilicity.
In addition, in order to ensure a clear image (visibility), low reflectance and antifogging in the detection wavelength region as well as in the presence or absence of light, temperature extremes, rain, fog, etc. It is desirable to have sex.

However, when the present inventors examined methods of carrying out Patent Documents 3 to 5, in the functional antireflection film described in Patent Document 3, even the antireflection film is sufficient because the uppermost layer is titanium oxide. It turned out that an antireflection function can not be obtained.
Moreover, in the anti-reflective film of patent document 4, since the uppermost layer consists of a non-hydrophilic inorganic compound which is a fluoride, it turned out that favorable super hydrophilicity is not expressed.
Furthermore, in the antireflective film described in Patent Document 5, it was found that the uppermost layer is composed of a hydrophilic inorganic compound such as silicon oxide, and superhydrophilicity and antifogging properties are exhibited when combined with the titanium oxide layer. In the sputtering pressure range at the time of film formation described in Patent Document 5, there are many items to be managed such as the occurrence of abnormal discharge and the decrease in discharge persistence, and the stable reproducibility is poor.

In general, a transparent substrate used for a front window of an optical system constituting a current camera or the like is required to have a reflectance of less than 1%. In addition, when the center wavelength of the optical system is not only visible light (wavelength lower limit is 360 to 400 nm, wavelength upper limit is 780 to 830 nm) but near infrared (wavelength 800 to 2500 nm) to infrared (wavelength 700 nm to 1 mm) There is also a demand that the transparent substrate have a reflectance of less than 1% at a specific wavelength within the wavelength range from visible light to near infrared light.
In view of the circumstances as described above, the present invention is a transparent antifogging antireflective film having antireflectivity that provides a reflectance of less than 1% at a specific wavelength, and superhydrophilicity and antifogging properties by photocatalytic reaction. An object of the present invention is to provide a cover substrate with an antifogging antireflective film and a method of manufacturing the antifogging antireflective film.
Another object of the present invention is to maintain the hydrophilic effect stably for a long time even under non-sunlight, without requiring special excitation such as ultraviolet light, and any of the wavelength range of 400 to 1500 nm. Anti-fogging anti-reflection coating with anti-fogging property that has an average reflectance of 1% or less in the wavelength range of 200 nm and can ensure clear visibility even under fog, rainfall, temperature change, etc. environment, anti-fogging reflection It is an object of the present invention to provide a method for producing a cover substrate with a protective film and an antifogging antireflection film.

As a result of intensive studies to solve the above problems, the present inventors found that a first dielectric film and a second dielectric having a refractive index lower than that of the first dielectric film on a transparent substrate. The body film is alternately laminated with at least four layers, and the uppermost layer is composed of an antireflective film which is the second dielectric film, and the first dielectric film is made of an inorganic compound exhibiting a photocatalytic reaction, The present invention is based on the finding that a transparent substrate having both antireflective properties and superhydrophilicity and antifogging properties by photocatalytic reaction can be obtained by the second dielectric film being made of a hydrophilic inorganic compound. It reached.
That is, according to the antifogging antireflective film of the present invention , the subject is the antifogging antireflective film, wherein the first dielectric film is formed on at least one surface of the transparent substrate. At least four or more layers of second dielectric films having a refractive index lower than that of one dielectric film are alternately stacked, and the uppermost layer is the second dielectric film, and the first dielectric film Is an inorganic compound exhibiting a photocatalytic reaction, the second dielectric film is a hydrophilic inorganic compound, and the film of the first dielectric film as the uppermost layer among the plurality of first dielectric films The thickness is 200 nm or more, and the film thickness of the uppermost second dielectric film among the plurality of second dielectric films is 20 nm or more, and the first dielectric film is X Intensity ratio of anatase (101) peak to rutile (110) peak in line diffraction anatase (101) Rutile (110) is 2.0 or more, intensity ratio of anatase (101) peak to anatase (200) peak Anatase (101) / anatase (200) is 2.0 or more, and anatase and rutile The reflectance of the antireflective film is made of a first arbitrary designated wavelength a (nm) in the wavelength range of 400 to 1500 nm, and is made of an inorganic compound mainly composed of titanium oxide, which is a mixed crystal, from the first arbitrary designated wavelength a (nm). Average reflectance in a range up to a second designated wavelength b (nm) greater than any designated wavelength by 200 nm is less than 1%, and a contact angle of water on the surface on the uppermost layer side exhibits 10 degrees or less Is solved by.

Since it is configured in this way, it is a laminate of a thin film having antireflectivity with a reflectance of less than 1% in a specific wavelength range, as well as photocatalytic reactivity and hydrophilicity, and the contact angle of water on the surface is It is possible to provide a transparent substrate having superhydrophilicity and antifogging property which is 10 degrees or less.
In addition, by laminating an inorganic compound film exhibiting a photocatalytic reaction and an inorganic compound film exhibiting hydrophilicity, and making the outermost surface layer an inorganic compound film exhibiting hydrophilicity, storage time in a dark place after 900 hours has passed. Also, it becomes possible to form a laminate capable of holding the contact angle of water on the outermost surface of the laminated film at 10 degrees or less.
In addition, by setting the film thickness of the uppermost first dielectric film to 200 nm or more as described above, the first dielectric film having crystallinity can be achieved. In addition, by setting the film thickness of the uppermost second dielectric film to 20 nm or more, the antireflection effect can be achieved.

Environment such as fog, rainfall, temperature change, etc. under sunlight or non-sunlight, because it is possible to ensure hydrophilicity even in a dark place where there is no ultraviolet light due to ultraviolet light such as sunlight or fluorescent light and also at room temperature Even under the condition, the hydrophilic effect can be maintained stably for a long time, and the antifouling property and the antifogging property can be secured. Further, by having the catalytic property, an antibacterial and antiviral effect can be obtained.
In a dark place without ultraviolet light and at room temperature, the contact angle of water can be kept at 10 degrees or less even after 900 hours after film formation, and the average reflectance of the desired wavelength band of 200 nm in the range of 400 to 1500 nm. As it can be kept at less than 1%, a clear view can be secured.
By providing a catalytic first dielectric film and a hydrophilic second dielectric film on the surface layer, and further forming an antireflective structure in consideration of optical elements, it is possible to obtain three types of catalytic property, hydrophilicity and antireflective ability. A laminate having two effects can be achieved, and more multiple effects can be obtained.

Also, the second dielectric film, it is preferable that made of an inorganic compound film mainly composed of silicon oxide.
The inorganic compound which comprises a 1st dielectric material film has a titanium oxide of anatase type crystal structure as a main component, and exhibits a photocatalytic reaction. The refractive index of this inorganic compound film is n = 2.2 to 2.5, and the refractive index of the hydrophilic inorganic compound film mainly composed of silicon oxide which is the second dielectric film is n = 1. Since they are from 4 to 1.5, any particulars required may be made by alternately laminating these high and low refractive index films and constructing the outermost surface layer with a low refractive index film Wavelength range, for example, in the range of 450 nm to 650 nm in the visible range with the lower limit of 360 to 400 nm and the upper limit of 760 to 830 nm, and in the range of 200 nm of any specific wavelength in the range of 900 nm to 1100 nm of the near infrared range of 800 to 2500 nm An antifogging antireflective film having an average reflectance of less than 1% can be formed.

Also, after the storage time has elapsed 900 hours in a dark place, the contact angle of water of the uppermost side of the surface, it is preferable that exhibits a 10 ° or less.
Since it comprises in this way, the functional film which can maintain hydrophilicity for a long period of time can be provided, without requiring special excitation by ultraviolet light etc.

Further, it is preferable that is anti-fogging antireflection film-transmissive cover base body according to any one of the.
Also provided is a method for producing anti-fogging antireflection film according to any one of the, at least one surface on the transparent substrate, the first dielectric film and, said first dielectric film Preferably, at least four or more layers of the second dielectric film having a refractive index lower than that of the second dielectric film are alternately laminated so that the uppermost layer is the second dielectric film.

According to the present invention, it is a laminate of a thin film having antireflection property and photocatalytic reactivity and hydrophilicity with a reflectance of less than 1% in a specific wavelength range, and the contact angle of water on the surface is 10 degrees or less It is possible to provide a transparent substrate having superhydrophilicity and antifogging properties.
In addition, by laminating an inorganic compound film exhibiting a photocatalytic reaction and an inorganic compound film exhibiting hydrophilicity, and making the outermost surface layer an inorganic compound film exhibiting hydrophilicity, storage time in a dark place after 900 hours has passed. Also, it becomes possible to form a laminate capable of holding the contact angle of water on the outermost surface of the laminated film at 10 degrees or less.

It is a schematic explanatory drawing which shows the structure of the antifogging anti-reflective film which concerns on one Embodiment of this invention. It is a graph which shows the X-ray-diffraction result of laminated body AF of Experiment 1-6. It is a graph which shows the X-ray diffraction of the laminated bodies G and H of Experiment Examples 7 and 8 and the laminated bodies I and J of Example 1, 2 of this invention. It is a graph which shows the measurement result of the contact angle of water of laminated body AD of test examples 1-4, 6-6. It is a graph which shows the measurement result of the contact angle of water of laminated body DF of test examples 4-6. It is a graph which shows the measurement result of the contact angle of water of laminated body HJ of Experiment 8 and Example 1, 2. Test Example 7, SiO ₂ stack of only G, is a graph showing the measurement results of the contact angle of water K. It is a graph which shows the spectral reflectance in wavelength 400-700 nm of the laminated body D of Experiment 4. FIG. 5 is a graph showing the spectral reflectance at a wavelength of 400 to 700 nm of the layered product I of Example 1; It is a graph which shows the spectral reflectance in wavelength 400-700 nm of the laminated body J of Example 2. FIG. 5 is a view showing a surface observation image of a laminate I of Example 1. FIG.

Hereinafter, the antifogging antireflection film AR according to an embodiment of the present invention will be described in detail with reference to the drawings. The following description is a non-limiting example, and the present invention is not limited thereto.
In the present specification, “photocatalyst” refers to a material that exerts a catalytic action when exposed to light. A titanium oxide photocatalyst is a typical example of the photocatalyst.
When exposed to light, the titanium oxide photocatalyst exerts a decomposing power to decompose various organic substances and a hydrophilic function that makes the surface easily wet with water. By decomposing ability, it exerts the action of removing stains and odors and antibacterial action, and by the hydrophilicity, when it receives rain water, it gets under the stains, exerts an effect of making the stains float up and sink off, and an antifogging effect.
In the present specification, "anatase (apyrite)" and "rutile (gold erythrocite)" are crystal forms of tetragonal titanium oxide.
Since the X-ray diffraction image is unique to each crystal and the lattice constant, that is, the interference angle of X-ray diffraction differs depending on the crystal system, the presence or absence of titanium oxide crystal in the mixture system and the inclusion of each crystal form of titanium oxide The rate can be examined and quantified by X-ray diffraction.

Furthermore, in the present specification, “water contact angle” (θ: contact angle) is a value that quantifies the degree of wetting by water, and when the solid surface is in contact with liquid and gas, It refers to the angle that the liquid surface makes with the solid surface at the boundary where three phases contact. The smaller the contact angle, the higher the hydrophilic character.
As used herein, "top layer" means the layer furthest from the substrate.

(Anti-fogging antireflective film)
As shown in FIG. 1, the antifogging antireflective film AR of the present embodiment is formed on at least one surface on a transparent substrate 10, and an underlayer 20 and a first dielectric are provided from the substrate 10 side. A high refractive index film 30 composed of an inorganic compound layer which is a film and a low refractive index film 40 composed of an inorganic compound layer which is a second dielectric film having a refractive index lower than that of the first dielectric layer alternately And the uppermost layer is configured to be the low refractive index film 40. A plurality of high refractive index films 30 and a plurality of low refractive index films 40 may be present. Further, the antifogging antireflective film AR may be formed on at least one surface of the substrate 10, and may be formed on the entire surface of the substrate 10 or may be formed on a predetermined portion of the surface. .

  The substrate 10 may be any of glass, resin (including film), ceramics, and others, and is a known transparent base material having a refractive index of about 1.4 to 1.7.

The underlayer 20 is a layer provided closest to the substrate 10 so as to be in contact with the substrate 10, and may be formed of the same material as the high refractive index film 30 described later or the same material as the low refractive index film 40. Dielectric film having a third refractive index other than the high refractive index film 30 and the low refractive index film 40 for the purpose of improving adhesion, adjusting the refractive index, and preventing atomic diffusion from the substrate 10, for example, high A thin film formed of a mixture of the material of the refractive index film 30 and the material of the low refractive index film 40, or any other film having an intermediate refractive index between the high refractive index film 30 and the low refractive index film 40 may be used. .
The high refractive index film 30 as the first dielectric film is a layer having a refractive index higher than that of the low refractive index film 40, and the refractive index is 1.9 to 2.5, more preferably 2.2 to 2. .5. For the high refractive index film 30, an inorganic compound which is a compound of a transition metal such as titanium, niobium, or zircon exhibiting a photocatalytic reaction is used. For example, a titanium oxide film having an anatase type crystal structure is suitably used.

In particular, the high refractive index film 30 is an inorganic compound thin film mainly composed of titanium oxide which is a photocatalytic thin film, and is a mixed crystal of anatase type and rutile type, and the peak intensity ratio of anatase (101) / rutile (110) Is 2.0 or more, preferably 3.0 or more, and the crystallinity of the anatase type titanium oxide is such that the peak intensity ratio of anatase (101) / anatase (200) is 2.0 or more, more preferably 3.0 or more It is good.
The film thickness of the high refractive index film 30 of the uppermost layer among the plurality of high refractive index films 30 formed in contact with the low refractive index film 40 of the uppermost layer farthest from the substrate 10 is 100 nm or more, preferably 200 nm or more .
The method for forming the high refractive index film 30 is not particularly limited, but film forming methods using a dry (dry) process such as evaporation, sputtering, ion plating, and CVD using vacuum can be used.

The low refractive index film 40 as the second dielectric film is a layer having a lower refractive index than the high refractive index film 30, and is a thin film having a refractive index of about 1.35 to 1.55.
For the low refractive index film 40, an inorganic compound exhibiting hydrophilicity is used. For example, a silicon oxide film is preferably used.
The film thickness of the low refractive index film 40 in the uppermost layer farthest from the substrate 10 is 5 nm or more, more preferably 1⁄4 or less of the central wavelength (λ) when the central wavelength of the specific wavelength region is λ nm.
The method of forming the low refractive index film 40 is not particularly limited, but similar to the high refractive index film 30, deposition methods using vacuum, sputtering, ion plating, CVD, and other film forming methods by dry (dry) processes are possible. is there.
The film thickness of each of the high refractive index film 30 and the low refractive index film 40 is the first arbitrary designated wavelength a (nm) from the first arbitrary designated wavelength a (nm) within the wavelength range of wavelength 400 to 1500 nm. The average reflectance in the range of 200 nm to the second arbitrary designated wavelength b (b = a + 200) larger by 200 nm is determined to be less than 1%.

In the high refractive index film 30 and the low refractive index film 40, the optical film thickness obtained by multiplying the film thickness by the refractive index of each layer is approximately λ / 20 to 1.1 λ when the central wavelength of the specific wavelength region is λ nm. Range. The specific wavelength range may be a range of 200 nm from the first arbitrary designated wavelength a to the second arbitrary designated wavelength b.
The high refractive index film 30 and the low refractive index film 40 stacked directly on the substrate 10 have the same optical constants or the same optical constants as those of the high refractive index film 30 and the low refractive index film 40 arranged directly above them. It is possible to form a substance having a corresponding value of the refractive index and the extinction coefficient, and in particular, a substance including a mixture of materials of the high refractive index film 30 and the low refractive index film 40 stacked directly on the substrate 10 There is no limitation on
The uppermost layer, the high refractive index film 30 and the low refractive index film 40, are respectively formed of titanium oxide and silicon oxide, but the other high refractive index films 30 and the low refractive index film 40 are each formed of titanium oxide. And inorganic dielectrics other than silicon oxide. The high refractive index film 30 other than the uppermost high refractive index film 30 may be titanium oxide without photocatalytic property, or may be made of other high refractive index material.

In the present embodiment, the high refractive index film 30 and the hydrophilic low refractive index film made of an inorganic compound exhibiting a photocatalytic reaction with a film thickness determined so that the average reflectance in a specific wavelength region is less than 1%. By alternately laminating 40 as shown in FIG. 1, an antireflective film AR having superhydrophilicity and antifogging properties can be obtained.
Further, the outermost low refractive index film 40 is a thin film exhibiting hydrophilicity, which is an inorganic compound film mainly composed of silicon oxide.

  Thus, the laminate formed on the transparent substrate exhibits a photocatalytic function and has a hydrophilic function, and from the first arbitrary specified wavelength a in the wavelength range of 400 to 1500 nm, the first arbitrary specified wavelength The average reflectance in the wavelength range of 200 nm to the second arbitrary designated wavelength b larger than 200 nm is less than 1%, and the contact angle of water on the surface is long at least 700 hours or more and 900 hours in the dark It is possible to form a good antifogging antireflective film that is 10 degrees or less even after storage for 1,800 hours.

  In the method of the present embodiment, the laminated structure of the high refractive index film 30 and the low refractive index film 40 can be consistently formed by physical vapor deposition such as vapor deposition and sputtering, so a film of several nm or less Thickness control is possible, and it is possible to obtain a lower reflectance than in the case where other methods such as coating and immersion are used in combination.

(Transparent cover base with antifogging antireflective film)
The substrate 10 on which the antifogging antireflective film AR of the present embodiment is formed is used as a cover substrate for an outdoor camera, a lidar (LIDAR: Light Detection and Ranging, or Laser Imaging Detection and Ranging), or instruments. Be
That is, the substrate 10 is processed in advance by cutting, molding, bonding or the like so as to have a cover shape such as an instrument, and the antifogging antireflective film AR of the present embodiment is applied to the processed substrate 10. A transmission cover substrate with an antifogging antireflective film is manufactured.
In addition, after the anti-fogging anti-reflection film AR of the present embodiment is provided on the substrate 10, the anti-fogging anti-reflection film AR may be processed by cutting, molding, bonding or the like so as to have a cover shape.
The anti-fogging anti-reflection coated transmission type cover substrate of this embodiment is used for a front window of an instrument etc., and a good visual field from the inside and a good visibility from the outside are maintained. Ru. Since the average reflectance in a specific wavelength range of 200 nm is 1% or less, transmission of an infrared beam and visual recognition of the indicator plate of the instrument from the outside are suitably performed according to the function of the instrument.

(Method of manufacturing antifogging antireflective film)
The antifogging antireflective film AR of the present embodiment is manufactured by the following steps.
The transparent substrate 10 is set in a vapor deposition apparatus, and the material of the base layer 20 made of a commercially available low refractive index film 40 material such as silicon oxide is set in an evaporation source to set the vacuum degree in the apparatus to 1.5 × 10. Exhaust to less than ^-3 Pa. Thereafter, while maintaining the substrate temperature at 200 to 300 ° C., the material is evaporated using an electron gun to form an underlayer 5 to a thickness of 5 to 50 nm on the substrate 10. At this time, if necessary, ions or the like of oxygen or argon, or a mixed gas thereof are assisted.
The base layer 20 may not be formed when the substrate 10 does not contain an alkali metal.

Thereafter, a commercially available high refractive index film 30 material such as titanium oxide is set in an evaporation source, the degree of vacuum in the apparatus is exhausted to less than 1.5 × 10 ⁻³ Pa, and the substrate temperature is set to 200 to 300 ° C. The material of high refractive index 30 is evaporated by using an electron gun while maintaining the same, and 20 to 50 nm of the material of high refractive index film 30 which is the first dielectric film, oxygen or argon, or those The high refractive index film 30 is formed while being irradiated with ions (ion current: 300 to 1000 mA) with the mixed gas of
Subsequently, a material of a low refractive index film 40 such as silicon oxide commercially available is set in an evaporation source, the degree of vacuum in the apparatus is exhausted to less than 1.5 × 10 ⁻³ Pa, and the substrate temperature is 200 to 300 ° C. While maintaining, a material 25 to 100 nm of the low refractive index film 40 which is the second dielectric film is formed as the low refractive index film 40 on the high refractive index film 30 using an electron gun. At this time, if necessary, ions or the like of oxygen or argon, or a mixed gas thereof are assisted.
Thereafter, the high refractive index film 30 and the low refractive index film 40 are sequentially formed in the same manner. However, at this time, the film thickness of the high refractive index film 30 is 100 nm or more, preferably 200 nm or more, and the film thickness of the low refractive index film 40 is 5 nm or more, more preferably 1/4 or less of the central wavelength (λ). Do.
A set of the high refractive index material 30 and the low refractive index material 40 and other materials can shorten the evacuation time if they are initially set in the rotary evaporation source. Above, the anti-fogging anti-reflective film AR of this embodiment is completed.
The antifogging antireflective film AR of the present embodiment can also be manufactured by other dry (dry) processes such as sputtering, ion plating, and CVD.

Hereinafter, the present invention will be described in more detail based on specific examples, but the present invention is not limited to these examples.
(Test Examples 1 to 8 Preparation of Laminates A to H with Two-Layer Structure)
A transparent glass substrate is set in a vapor deposition apparatus, a commercially available titanium oxide is set as an evaporation source, the degree of vacuum in the apparatus is evacuated to less than 1.5 × 10 ⁻³ Pa, and the substrate temperature is maintained at 300 ° C. The titanium oxide is evaporated while performing ion assist using an electron gun, and the first dielectric film, titanium oxide film 20 nm, 50 nm, 100 nm, 200 nm, is formed while being irradiated with oxygen ions (ion current 1000 mA). did.
Subsequently, silicon oxide as a rotary evaporation source is set, and a silicon oxide film as a second dielectric film is formed on each titanium oxide film to a thickness of 20 nm using an electron gun. I got the body A ~ D.

The crystallinity of each of the four types of laminates A to D of Test Examples 1 to 4 in which films were formed was investigated using an X-ray diffraction apparatus (XRD-H250315-1974, manufactured by Nippon Denshi K.K.). The X-ray diffraction of laminates A to D of Test Examples 1 to 4 is shown in FIG.
No crystal orientation is observed in the laminate A (Test Example 1) having a film thickness of 20 nm of the titanium oxide film, and some laminates B (Test Example 2) having a film thickness of 50 nm have some anatase (101) and rutile (110). Although the orientation was observed, it did not come to a prominent peak. In the laminate C with a film thickness of 100 nm (Test Example 3) and the laminate D with a film thickness of 200 nm (Test Example 4), alignment was observed in the crystals. It was found that as the film thickness of titanium oxide increases, the crystal orientation becomes clear and the (200) orientation of anatase type becomes clear. Although the ratio of (101) / (200) of the anatase type is 2.0 or more, the ratio of anatase (101) / rutile (110) becomes larger as the film thickness of the titanium oxide film increases; The value of 0 or more was when the film thickness of titanium oxide was 200 nm.

  Next, in order to verify the ion assist effect, when forming a titanium oxide film 200 nm, the ion current of oxygen ions is applied at 500 mA and 300 mA respectively, and then a silicon oxide film 20 nm is formed for each titanium oxide film. Film formation was performed to obtain laminates E and F of Test Examples 5 and 6, respectively.

Similar to the laminates A, B, C, and D of Test Examples 1 to 4 with respect to each of the two types of laminates E and F (Test Examples 5 and 6) formed into a film, crystallinity using an X-ray diffraction apparatus investigated. The X-ray diffraction of the laminates E and F (Test Examples 5 and 6) is shown in FIG. The X-ray diffraction charts of FIG. 2 and FIG. 3 are shown by being overwritten in order to make it easy to compare the difference in the film formation requirements.
The crystal orientation is observed at any of the ion currents of 500 mA and 300 mA, and the anatase type (101) / (200) ratio is 2.0 or more, and the anatase (101) / rutile (110) ratio is also 2 .0 or more. In addition, it was found that the peak intensity at an ion current of 300 mA is lower than the ion current of 500 mA, and at least an ion current of 300 mA or more is required for better crystalline growth under the present film forming conditions.

Next, setting the film thickness of the titanium oxide film which is the first dielectric film to 100 nm, the substrate temperature at the time of forming the titanium oxide film and the silicon oxide film is set low, and silicon oxide which is the second dielectric film It was confirmed that the thickness of the film was increased (stacked body G) and the case where the silicon oxide film was formed on the underlayer at normal temperature (laminated body H).
In the film formation of the laminate G, first, a commercially available titanium oxide is set as an evaporation source, the degree of vacuum in the apparatus is exhausted to less than 1.5 × 10 ⁻³ Pa, and then the substrate temperature is maintained at 200 ° C. Then, titanium oxide was evaporated using an electron gun, and a titanium oxide film 100 nm, which was a first dielectric film, was formed on the substrate surface while being irradiated with oxygen ions. Subsequently, silicon oxide as a rotary evaporation source was set, the silicon oxide was evaporated using an electron gun, and a silicon oxide film as a second dielectric film was formed to a thickness of 70 nm on the titanium oxide film.

In the film formation of the layered product H, after evacuating the in-apparatus vacuum degree to less than 1.5 × 10 ⁻³ Pa and then maintaining the plate temperature at 300 ° C., a silicon oxide film which is a second dielectric film as a lower layer Of 20 nm. Thereafter, a titanium oxide film 100 nm, which is a first dielectric film, was formed while being irradiated with oxygen ions. Furthermore, a silicon oxide film 20 nm which is a second dielectric film was formed thereon.

Example 1 Preparation of Laminate I of Four-Layer Structure
In order to obtain a four-layered laminated body which is a basic configuration, the transparent glass substrate 10 is set in a vapor deposition apparatus, and a commercially available titanium oxide is set as an evaporation source, and the vacuum degree in the apparatus is 1.5 × 10 ^−3. After exhausting to less than Pa, titanium oxide is evaporated while performing ion assist using an electron gun while maintaining the substrate temperature at 300 ° C., and a titanium oxide film 20 nm as a first dielectric film is formed on the surface of the substrate 10 The high refractive index film 30 was formed while being irradiated with oxygen ions (ion current: 1000 mA).
Subsequently, the amount of introduced oxygen gas is changed to 40 sccm, silicon oxide as a rotary evaporation source is set, and a low refractive index film 40 made of a silicon oxide film as a second dielectric film using an electron gun. Was formed on the high refractive index film 30 of titanium oxide film to a thickness of 25 nm. A high refractive index film 30 of titanium oxide, which is the first dielectric film, is formed to a film thickness of 240 nm under the first film formation conditions of titanium oxide, and finally a low dielectric film consisting of a silicon oxide film which is the second dielectric film. The refractive index film 40 was formed to 90 nm to obtain a laminate I of Example 1.

(Example 2 Preparation of Laminate J of Base Layer 20 + 4 Layer Structure)
In this example, a laminate J of Example 2 in which a silicon oxide film as a second dielectric film was formed as the base layer 20 was produced.
A transparent glass substrate 10 was set in a vapor deposition apparatus, a commercially available silicon oxide was set as an evaporation source, and the degree of vacuum in the apparatus was evacuated to less than 1.5 × 10 ⁻³ Pa. Thereafter, while maintaining the substrate temperature at 300 ° C., silicon oxide was evaporated using an electron gun, and a silicon oxide film as a second dielectric film was formed on the substrate 10 as a base layer 20 to a thickness of 20 nm.

  Thereafter, as in Example 1, commercially available titanium oxide is set as an evaporation source, titanium oxide is evaporated while performing ion assist using an electron gun while maintaining the substrate temperature at 300 ° C. On the silicon oxide film, a titanium oxide film 20 nm, which is a first dielectric film, was formed as a high refractive index film 30 while being irradiated with ions (ion current: 1000 mA). Subsequently, a commercially available silicon oxide is set as an evaporation source, and a silicon oxide film as a second dielectric film is used as a low refractive index film 40 on the high refractive index film 30 of titanium oxide using an electron gun. , 33 nm formed. Under the first titanium oxide film forming conditions, the first dielectric film titanium oxide film thickness 270 nm is formed as the high refractive index film 30, and finally the second dielectric film silicon oxide film is low. The refractive index film 40 was formed to 98 nm to obtain a laminate J of Example 2.

  Laminates A to J prepared under a series of film forming conditions of Test Examples 1 to 8 and Examples 1 and 2, and a stack in which only a silicon oxide film was formed in the same process as the silicon oxide film formation of Test Example 1 For body K, substrate temperature at film formation, film thickness of each layer, ion assist current at film formation, ratio of (101) / (200) anatase type by X-ray analysis, and anatase (101) / rutile (110) A list of the ratios of) is given in Table 1.

Further, only the silicon oxide film was formed in the same steps as the film formation of the laminates A to J prepared under the series of film forming conditions of Test Examples 1 to 8 and Examples 1 and 2 and the silicon oxide film formation of Test Example 1 About the laminated body K, the contact angle of water on the surface of the laminated body was measured immediately after the film formation (0 hour) and after 48 to 1800 hours after the film formation.
In order to avoid the influence of ultraviolet light as much as possible, the film formation sample was covered with an aluminum box immediately after the film formation, removed each time it was measured, measured the contact angle of water, and stored it in the same manner immediately. . The contact angle was measured by a θ / 2 method using a CA-X type apparatus manufactured by Kyowa Interface Science. The measurement results are shown in Table 2, and graphs of time lapse and contact angle are shown in FIGS.

From the results of Table 2 and FIGS. 4 to 7, in the laminate F of Test Example 4 to the laminate F of Test Example 6, the laminate H of Test Example 8 and the laminates I and J of Examples 1 and 2, water Contact angle of 10 degrees or less.
And, in the laminate D of Test Example 4 to the contact angle of water of 10 degrees or less, the laminate F of Test Example 6, the laminate H of Test Example 8, and the laminates I and J of Examples 1 and 2, The anatase type (101) / (200) ratio and the anatase (101) / rutile (110) ratio were each 2.0 or more.
In the laminate D of Test Example 4 to the contact angle of water of 10 degrees or less, the laminate F of Test Example 6, the laminate H of Test Example 8, and the laminates I and J of Examples 1 and 2, Of the titanium oxide film which is the first dielectric, the film of the outermost layer is 200 nm or there is a silicon oxide layer as the underlayer 20 and the outermost layer of the titanium oxide film which is the first dielectric The film was 200 nm.
From this result, in the titanium oxide film which is the first dielectric, in the film thickness of 100 nm or more, preferably 200 nm or more, the ratio of (101) / (200) of anatase type and anatase (101) / rutile (110) It has been found that the preferred crystallinity of 2.0 or more can be obtained, respectively. In addition, in the case where there is a silicon oxide layer as the base layer 20, it was found that suitable crystallinity can be obtained with a film thickness of 100 nm or more of the titanium oxide film. Furthermore, it was found that no crystal orientation occurs at a substrate temperature of 200 ° C., and a substrate temperature of 300 ° C. or more is necessary to obtain suitable crystallinity.

  The crystallinity of the titanium oxide film, which is an inorganic compound exhibiting a photocatalytic reaction, which is the first dielectric film, involves interposing a thin film of silicon oxide in the lower layer, ion assistance during film formation, and temperature during film formation. It was found that the aspect can be changed by changing, and it is possible to obtain crystallinity of the titanium oxide film by properly combining these conditions.

  Further, in the results of Table 2, the laminate D of Test Example 4 in which the contact angle of water was 10 degrees or less, the laminate F of Test Example 6 and the laminate F of Test Example 8 and the laminate of Examples 1 and 2 In the bodies I and J, the film of silicon oxide as the second dielectric formed on the outermost layer was at least 20 nm or more.

  From the above, the crystallinity of the titanium oxide of the inorganic compound exhibiting a photocatalytic reaction which is the first dielectric film, in particular, the (101) / (200) ratio of anatase type, and of the anatase (101) / rutile (110) When the ratio of each is 2.0 or more, and the film of the hydrophilic inorganic compound which is the second dielectric film is 20 nm or more, the contact angle of water is 10 degrees or less over a long time even in the dark It became clearer than the measurement result of this example that it can hold.

With regard to the reflectance, FIG. 8 shows the spectral reflectance of the laminate D of Test Example 4 comprising a two-layer laminate structure of titanium oxide 200 nm and silicon oxide 20 nm, and the laminate I of Example 1 comprising a four-layer lamination standard configuration. The spectral reflectance of the laminate J of Example 2 provided with the 20 nm underlayer 20 is shown in FIG. 10, and the spectral reflectance of the laminate J of Example 2 is shown in FIG.
In Test Example 4, as shown in FIG. 8, the reflectance at a wavelength of 400 to 700 nm was 3 to 33%, whereas in Examples 1 and 2, 500 and 500, as shown in FIGS. The reflectance in the specific wavelength range of 200 nm of ̃700 nm was 1% or less.

The optical thickness n _d at 550 nm is 460 in the first layer (titanium oxide film) of Test Example 4, 29.2 in the second layer (silicon oxide film), and the first layer height in Example 1 The refractive index film 30 (titanium oxide film) is 46, the second low refractive index film 40 (silicon oxide) is 36.5, and the third high refractive index film 30 (titanium oxide) is 552, 4 The layer low refractive index film 40 (silicon oxide film) is 131.4, the base layer 20 (silicon oxide film) of Example 2 is 29.2, and the first layer high refractive index film 30 (titanium oxide film) 46, the second layer low refractive index film 40 (silicon oxide film) is 48.18, the third layer high refractive index film 30 (titanium oxide film) is 621, the fourth layer low refractive index film 40 (silicon oxide film) Membrane) was 143.08.
In addition, the contact angles of water of the laminates I and J of Examples 1 and 2 maintain 10 degrees or less even after 1000 hours, and in Example 1 10 degrees or less even after 1800 hours. It has been confirmed to maintain.

In addition, the surface of the laminate of Example 1 was measured by an atomic force microscope (AFM, Atomic Force Microscope, manufactured by Olympus, NV 2000). AFM is a type of SPM (scanning probe microscope). SPM is a general term for a microscope that scans the surface of a sample with a probe (probe) to know its surface shape and physical properties. With AFM, it is generated between atoms at the tip of the probe and atoms present on the surface of the sample Measure using atomic force (gravity, repulsion).
In the AFM of this example, a range of 5 μm × 5 μm was measured. The measurement result and surface observation image are shown in FIG.

The Profile Curve (cross-sectional curved surface) in the middle of the left column of FIG. 11 is a numerical value obtained from the cross-sectional curved surface from which only noise is removed from the measured raw data of AFM. The roughness parameters include SPa, SPq, SRmax, SPp, and SPv, and the measured values of these roughness parameters in this example are shown in the left column of FIG. Moreover, the definition of these roughness parameters is as follows.
SPa (average roughness in a sectional curved surface) is a numerical value obtained by summing the absolute values of the distances from the center line (or center plane). It represents the average roughness of the measured line or surface.
SPq (root mean square in a sectional curved surface) is obtained by squaring the distance from the center line (or center plane) and taking the square root of the value obtained by averaging the sum. It represents the variation of roughness.

SRmax (maximum height of the sectional curved surface) is the sum of the peak farthest from the center line (or center plane) and the valley farthest from the center line (or center plane), and is the maximum value of the measured in-plane roughness. Anomalous particle-like projections increase the peak height, and flaws increase the valley depth, so these surface anomalies affect this figure.
SPp (the maximum distance between the peak and the central plane in the sectional curved surface) is the distance between the central line (or central plane) and the mountain farthest from the central line.
SPv (the maximum distance between the valley bottom and the center plane in the sectional curved surface) is the distance between the center line (or center plane) and the valley farthest from the center line.

On the other hand, the Roughness Curve (roughness surface) is a numerical value obtained from the roughness surface from which the noise and the wave have been removed from the raw measurement data of AFM. The roughness parameters include SRa, SRq, SRy, SRp and SRv, and the measured values of these roughness parameters in this example are shown in the lower left column of FIG. Moreover, the definition of these roughness parameters is as follows.
SRa (average roughness in a roughness surface) is a value obtained by summing the absolute values of the distances from the center line (or center plane) and averaging, and represents the average roughness of the measured line or surface There is. SRa is described as Ra in JIS (Japanese Industrial Standard).
SR q (root mean square in the roughness surface) is obtained by squaring the distance from the center line (or center plane) and taking the square root of the value obtained by averaging the sum. It represents the variation of roughness. SRq is described as RMS in JIS (Japanese Industrial Standard).

The SRy (maximum height of the roughness surface) is the sum of the peak farthest from the center line (or center plane) and the valley farthest from the center line (or center plane), and is the maximum value of the roughness in the measured plane. Anomalous particle-like projections increase the peak height, and flaws increase the valley depth, so these surface anomalies affect this figure. SRy is described as Rz (or PV) in JIS (Japanese Industrial Standard).
SRp (the maximum distance between the peak and the center plane in the roughness surface) is the distance between the center line (or center plane) and the peak farthest from the center line.
SRv (the maximum distance between the valley bottom and the center plane in the roughness surface) is the distance between the center line (or center plane) and the valley farthest from the center line.
In this example, since 1/3 of the length of one side of the measurement range is taken as the cutoff value of the undulation, undulations of wavelengths of 1.667E + 03 nm or more are removed in each roughness parameter of the Roughness Curve.
The average surface roughness Ra of this example was in the range of 3 to 4 nm, and the in-plane maximum height difference Rmax was in the range of 20 to 40 nm.

  From the above test examples and examples, the configuration as to whether or not the underlayer 20 is included, and the titanium oxide film being the first dielectric film as the second layer from the outermost layer selected within the range of a film thickness of 100 nm or more Configuration, spectral characteristics in the near infrared region, etc., for the optical design on condition that the first dielectric film is made of an inorganic compound exhibiting photocatalytic reaction and the second dielectric film is made of a hydrophilic inorganic compound. It turned out that it can design freely within the limits.

AR antireflective film 10 substrate 20 underlayer 30 high refractive index film 40 low refractive index film

Claims (5)

Antifogging antireflective film,
At least four or more layers of a first dielectric film and a second dielectric film having a refractive index lower than that of the first dielectric film are alternately stacked on at least one surface of a transparent substrate And the uppermost layer is the second dielectric film,
The first dielectric film is made of an inorganic compound exhibiting photocatalytic reaction,
The second dielectric film is made of a hydrophilic inorganic compound,
The film thickness of the first dielectric film of the uppermost layer among the plurality of first dielectric films is 200 nm or more, and the second of the uppermost layer of the plurality of second dielectric films is Film thickness of the dielectric film is 20 nm or more,
The first dielectric film has an anatase (101) / rutile (110) intensity ratio of anatase (101) peak to rutile (110) peak in X-ray diffraction of 2.0 or more, and anatase (200) An intensity ratio of anatase (101) peak to peak anatase (101) / anatase (200) is 2.0 or more, and it is composed of an inorganic compound mainly composed of titanium oxide which is a mixed crystal of anatase and rutile,
The reflectance of the anti-reflection film is a first designated wavelength a (nm) within a wavelength range of 400 to 1500 nm and a second designated wavelength b (nm) larger by 200 nm than the first designated wavelength. The antifogging anti-reflection film characterized in that the average reflectance in the range up to is less than 1%, and the contact angle of water on the surface on the top layer side is 10 degrees or less.   The antifogging antireflective film according to claim 1, wherein the second dielectric film is made of an inorganic compound film containing silicon oxide as a main component.   The antifogging antireflective film according to claim 1 or 2, wherein a contact angle of water on the surface on the top layer side exhibits 10 degrees or less after storage time in a dark place for 900 hours.   A transmission cover substrate with an antifogging antireflective film according to any one of claims 1 to 3. A method for producing an antifogging antireflective film according to any one of claims 1 to 3 , which is:
The first dielectric film and the second dielectric film having a refractive index lower than that of the first dielectric film are alternately displayed on at least one surface of the transparent substrate. A method for producing an antifogging antireflective film, comprising laminating at least four layers so that the upper layer is the second dielectric film.