WO2011027872A1

WO2011027872A1 - Inorganic structure, method for producing same, and method for producing inorganic thin film

Info

Publication number: WO2011027872A1
Application number: PCT/JP2010/065177
Authority: WO
Inventors: 俊也渡部; 直哉吉田; 遼祐横西; 隆晶今井; 利典大倉; 幸信横田; 長川陳; 優子柴山; 章中島; 勤古田
Original assignee: 国立大学法人東京大学; 国立大学法人東京工業大学; 財団法人神奈川科学技術アカデミー
Priority date: 2009-09-04
Filing date: 2010-09-03
Publication date: 2011-03-10
Also published as: JPWO2011027872A1

Abstract

Disclosed is a method for producing an inorganic structure, which comprises a step of preparing a material for an inorganic structure, and a water vapor treatment step in which the water droplet falling angle of the surface of the material for an inorganic structure is decreased by subjecting the material for an inorganic structure to a water vapor treatment.

Description

INORGANIC STRUCTURE AND METHOD FOR PRODUCING THE SAME

The present invention relates to an inorganic structure, a manufacturing method thereof, and a manufacturing method of an inorganic thin film.

Since the water-repellent surface is a thermodynamically stable surface with little adhesion of liquid or organic matter, it is widely used industrially as a dirt prevention surface or a droplet adhesion prevention surface.
For example, in automobile windshields, the field of view is ensured by applying or baking a water-repellent polymer (water-repellent coating) to easily slide down raindrops that adhere in rainy weather (for example, special features (See Kaihei 6-340451).
In various processes in food and chemical production lines, fluorine-based water-repellent coatings are used for the purpose of preventing liquid adhesion. Further, even household goods such as frying pans are coated with fluorine for the purpose of preventing food adhesion (see, for example, JP-A-2008-212523).

However, since these water-repellent coatings are organic substances, there is a problem that the wear resistance and durability are basically insufficient.
For example, an organic compound-based water-repellent coating made of a fluorine-based or silicon-based organic compound is used to prevent a reduction in visibility of an automobile windshield. These organic compound water-repellent coatings are inferior in mechanical durability as compared to glass surfaces, and therefore their lifetime is limited to several months to at most several years. For this reason, there is a problem that an additional coating process at a dealer or the like becomes necessary. Such a problem is found in all uses such as prevention of liquid adhesion, and a fundamental improvement has been desired.

As a solution to the problems of wear resistance and durability, it is conceivable to make the surface of an inorganic material having durability equal to or higher than that of glass by some method.
However, since water repellency is improved by forming a more thermodynamically stable surface compared to the interface with water, organic compounds are better than inorganic compounds (metals and oxides, etc.). Obviously it is advantageous, and inorganic materials have not been used in the past.

However, as a result of earnestly conducting theoretical studies on wettability, the inventors theoretically have the possibility of obtaining a surface that repels water by controlling the physical and chemical properties of the surface. I thought it was suggested.
The following idea is described.
The Young's formula expressing the wettability of the solid by the balance of the surface tension of the interface is shown in the following formula (1).

γ _SV = γ _SL + γ _LV cos θ Equation (1)

In equation (1), θ is the contact angle, γ _SL is the solid (solid) -liquid (liquid) interfacial tension, γ _LV is the liquid (liquid) -vapor (gas) interfacial tension, and γ _SV is solid (solid). Solid) -vapor (gas) interfacial tension.
As long as this equation (1) is followed, θ is inevitably small when γ _SV is large.
Large material thus gamma _SV is, for example, inorganic oxides are not suitable for water-repellent applications.
However, the water repellency required for actual applications does not necessarily need to be thermodynamically water repellant.
That is, in many cases, it is sufficient that water droplets and the like are easily removed. In this case, what is required is not a static water repellency represented by a contact angle but a dynamic water repellency (sliding property). Regarding this dynamic water repellency, a basic theory is not necessarily established, but it is known that extremely fine surface non-uniformity affects its properties.

The present inventors have conducted research and development to increase the water repellency of the inorganic surface as much as possible, but this time, the water-sliding surface on which water drops fall at a slight angle is coated with an oxide such as zirconia, alumina, or hafnia (inorganic thin film). ).
Furthermore, the present inventors have been able to produce inorganic solids (glass articles and metal articles) having a water-sliding surface where water drops fall at a slight angle.
The technology developed this time can be expected to be used in various applications as a super-durable water repellent coating technology.

The present invention has been made based on the above viewpoint.
That is, there is a demand to provide an inorganic structure having a surface excellent in water droplet removal property (sliding property) and having excellent durability and a method for producing an inorganic structure capable of producing the inorganic structure. Yes.
Moreover, it is required to provide a method for producing an inorganic thin film capable of producing an inorganic thin film having a surface excellent in water droplet removal property (sliding property) and further excellent in durability.

This paper describes the concept of how to solve the problem from the theoretical background of this technology.
The present inventors examined the contact angle and the falling angle of organic water-repellent materials (FAS; 1H, 1H, 2H, 2H-perfluorodecyltrimethoxys and ODS; octadecyltrimethoxysilane) with various production conditions changed.
As a result, it was found that there is no clear correlation between the static water repellency expressed by the contact angle and the dynamic water repellency expressed by the falling angle (N. Yoshida et. al, Journal of the American Chemical Society 128 (3), 743-747 (2006)).
Furthermore, even if the sliding angle is 20 ° to 30 °, there are some that have excellent dynamic water repellency even if the static water repellency is not necessarily high, such as those with a contact angle of around 70 °. I understood.
As an expression showing dynamic water repellency, Furmidge's expression (2) is known.

mg sinα = ωγ _LV (cosθ _r −cosθ _a ) Equation (2)

In equation (2), m is the mass of the water droplet, g is the acceleration of gravity, α is the falling angle of the water droplet, ω is the width of the water droplet in the direction perpendicular to the direction in which the water droplet falls, γ _LV is the interfacial tension of liquid-vapor, θ _a is the advancing contact angle, and θ _r is the receding contact angle.
Here, the difference between the advancing contact angle theta _a and receding contact angle θ _{_r} (cosθ _r -cosθ _a), it referred to as the contact angle hysteresis, as is clear by the formula (2), rolling property of water drops This is determined by the contact angle hysteresis.
That is, in order to improve dynamic water repellency, it is necessary to reduce the contact angle hysteresis.

Research on such contact angle hysteresis has been addressed since the 1960s.
However, it is not clear why such hysteresis that causes dynamic water repellency occurs. There is no doubt that at least the advancing contact angle must be smaller and the receding contact angle larger, but these cannot be controlled independently. If the hydrophilicity is extremely high, the advancing contact angle becomes small, but it becomes difficult for water droplets to peel from the surface on the receding surface, so that it is not possible to expect lubricity. In order to improve the water slidability, it is first necessary to form a rounded water droplet, and for that purpose, the contact angle needs to have a high value to some extent. Therefore, it is necessary to first consider a method for providing a means for increasing the contact angle θ.

方 One way to improve the static contact angle of the same material is to reduce the surface roughness as much as possible. The Wenzel equation including the surface roughness factor r is expressed by the following equation (3).

cosθ ′ = r (γ _SV −γ _SL ) / γ _LV = rcosθ (3)

In the above formula (3), θ ′, r, γ _SV , γ _SL , γ _LV, and θ are respectively the contact angle on the rough surface and the Wenzel roughness factor (actual surface area increased by the surface roughness). Divided by the apparent surface area), the solid-gas surface tension, the solid-liquid interfacial tension, the liquid-gas surface tension, and the contact angle on a smooth surface.

According to the above formula (3), as the surface roughness increases, the hydrophilic surface is emphasized more hydrophilicly, and the water-repellent surface is emphasized more water-repellently. In the case of inorganic oxides, since θ is usually 90 ° or less, the surface roughness should work in the direction of decreasing the contact angle. Therefore, the contact angle is increased by improving the surface smoothness as much as possible.
When the average surface roughness and contact angle of various inorganic oxides and metal surfaces are measured and the relationship is evaluated, the influence of the surface roughness is remarkable, and the change in the direction indicated by the Wenzel equation can be confirmed.
However, the effect is not uniform over the entire region where the surface roughness changes, and the influence of the surface roughness is particularly large in the nanometer region. Specifically, as shown in FIGS. 5 and 6, when the surface roughness is reduced in the nanometer region, the contact angle rapidly increases with the surface roughness (Ra) of 2 nm as a boundary. The Wenzel effect is a correction of Young's formula, assuming that the increase in unevenness is an increase in contact area, and assumes the effect in the micrometer region where thermodynamic uniformity can be expected. The Wenzel effect does not seem to have been predicted to be effective in the nanometer range, where intermolecular interactions are a problem.
In fact, the area of surface roughness of inorganic substances that has been measured as the Wenzel effect in previous studies is limited to the micrometer range, and the influence on the contact angle was evaluated over a wide range of surface roughness including the nanometer range. I can't find anything.
Therefore, there is further verification as to whether the change in the contact angle in the nanometer region is the same as the so-called Wenzel effect, but it is clear that such a large effect can be obtained in fact. By utilizing this fact, the contact angle of the inorganic substance can be increased.

Next, in order to increase the dynamic water repellency, _{a method} for reducing the hysteresis cosθ _r -cosθ _a will be described.
As the origin of hysteresis, Israelachvili points out 1) surface roughness or structural inhomogeneity, 2) chemical inhomogeneity, etc. (JN Israelachvili, translated by Yasuo Kondo / Hiroyuki Oshima, Force and surface force "2nd edition, Asakura Shoten (1996)). These are to reduce the advancing contact angle theta _a, it is believed to be a factor to increase the receding contact angle theta _r.
The present inventor has found that the correlation between the contact angle and the dynamic water repellency appears clearly by smoothing the organic water-repellent surface on the nanometer scale (N. Yoshida et. al, Journal of the American Chemical Society 128 (3), 743-747 (2006)).
On the organic water-repellent surface, θ in the Wenzel equation exceeds 90 °, so the contact angle tends to decrease rather when the surface roughness is reduced. Even so, the reason why the dynamic water repellency is improved is thought to be that the hysteresis cosθ _r -cosθ _a is reduced by reducing the surface roughness. Similar effects can be expected with inorganic oxides.

When the receding surface of a water droplet falling on the alumina thin film is observed with an optical microscope, the water droplet does not recede uniformly, and it looks as if the water droplet is caught at that location (for example, see FIG. 2 described later). .
Many points (resistance points) at which such water droplets are prevented from retreating are observed on the surface where the water droplets are not easily dropped.
If the water drop receding surface is observed closely, it can be inferred that θ _r is reduced by such a resistance point. The cause of the resistance point is considered to be a minute surface protrusion or depression, the presence of a chemical foreign substance, and a change in physical properties. Although it is difficult to observe the advancing surface, the situation will be similar where a myriad of similar resistance points prevent the water droplet from advancing. Hysteresis cosθ _r -cosθ _a can be reduced by eliminating such causes as much as possible and taking a complex means for making the physical and chemical properties of the surface uniform. On the other hand, such a surface having excellent tumbling properties is considered to be in a state where the physical and chemical properties of the surface are extremely uniform and the number of resistance points is less than a certain level.
As a specific method for obtaining such a surface, it will be described later that steam treatment under appropriate conditions disclosed in this specification is effective.
4 quadrants with two axes of dynamic water repellency and static water repellency: (1) Super hydrophilic state, that is, a state where the contact angle is small and the substrate is tilted, the water droplets adhere and do not move. 2) State of super water repellency, that is, a state where water drops easily fall down, (3) State of "contact angle is high but does not fall down" as seen in fluorine-based water repellent coatings, and (4) Contact angle Is not so high, but the drop angle of water droplets is low, and it is considered that there is a state showing dynamic water repellency.

The present invention provides a coating with high surface smoothness by a sol-gel method to develop a high contact angle, and then performs steam treatment as a means for homogenizing the physical and chemical properties of the surface, and an inorganic structure. It is one of these four quadrants by performing steam treatment as a means to make the physical and chemical properties of the surface uniform, etc. “(4) The contact angle is not so high but the drop angle of the water droplet is low. It is clarified that an inorganic structure located in the “state exhibiting water repellency” is obtained. The material corresponding to the four quadrant (4) is a completely new material that has not been obtained in the past.

Based on the viewpoint shown above, in order to improve the water slidability of the inorganic material that is originally hydrophilic, as a result of repeating an enormous experiment that can be considered, the following relatively simple process centered on steam treatment, I found it extremely effective. Although the phenomenon that water is repelled by treatment with water vapor seems to be a phenomenon that is difficult to understand at first glance, the water vapor treatment is a treatment in which a remarkable effect on inorganic substances is recognized as described later. Such specific means for solving the above-mentioned problems are as follows.

<1> a step of preparing an inorganic structure material;
A steam treatment step for reducing a water droplet falling angle on the surface of the inorganic structure material by steaming the inorganic structure material;
The manufacturing method of the inorganic structure which has this.
<2> The steam treatment is performed by exposing the inorganic structure material to a steam atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more. Production method.
<3> The steam treatment according to <1> or <2>, wherein the steam treatment is performed by exposure to a steam atmosphere having a product of temperature (° C.) and relative humidity (%) of 2000 ° C. ·% or more and 10,000 ° C. ·% or less. A method for producing an inorganic structure.
<4> The method according to any one of <1> to <3>, further comprising a pretreatment step of performing a pretreatment for removing organic substances on the surface of the inorganic structure material with respect to the inorganic structure material before the water vapor treatment step. 2. A method for producing an inorganic structure according to item 1.
<5> The method for producing an inorganic structure according to <4>, wherein the pretreatment is at least one of heat treatment at 100 ° C. or higher, ultrasonic cleaning treatment, and ultraviolet irradiation treatment.
<6> Any one of <1> to <5>, including a post-treatment step of performing a heat treatment at a temperature not lower than the steam temperature and not higher than 300 ° C. as a post-treatment on the inorganic structure material after the water vapor treatment step. The manufacturing method of the inorganic structure as described in a term.
<7> The method for producing an inorganic structure according to any one of <1> to <6>, wherein the inorganic structure material includes at least one selected from a metal, an alloy, an inorganic oxide, and glass. .
<8> The inorganic structure material is selected from the group consisting of an inorganic solid containing at least one selected from stainless steel, soda lime glass, and quartz glass, or alumina, ceria, titania, hafnia, and silica. The method for producing an inorganic structure according to any one of <1> to <7>, which is an inorganic thin film containing at least one kind.

<9> A coating film forming step of forming a coating film by coating a coating liquid containing a precursor of an inorganic oxide on a support;
A heat treatment step of heat-treating the formed coating film at a temperature of 300 ° C. or higher;
A steam treatment step for reducing a water droplet falling angle on the surface of the heat-treated coating film by steam-treating the heat-treated coating film;
The manufacturing method of the inorganic thin film which has.

<10> An inorganic structure in which the density of resistance points that inhibit the sliding of water droplets on the surface is 10 pieces / 30 mm ² or less.
<11> Using a cantilever made of Si ₃ N ₄ having a spring constant in the thickness direction of 0.05 N / m and a pressing force of 14 nN, a region where the friction force measured by a friction force microscope is 10 nN or less, and Using a cantilever made of Si ₃ N ₄ having a spring constant in the thickness direction of 0.05 N / m and at a pressing pressure of 14 nN, at least in a region where the dynamic friction coefficient measured by a friction force microscope is 1.0 or less An inorganic structure containing one surface.
<12> The inorganic structure according to <10> or <11> obtained by being treated in a steam atmosphere.
<13> The inorganic structure according to any one of <10> to <12>, comprising at least one selected from metals, alloys, inorganic oxides, and glass.
<14> Inorganic solid containing at least one selected from stainless steel, soda lime glass, and quartz glass, or at least one selected from the group consisting of zirconia, alumina, ceria, titania, hafnia, and silica The inorganic structure according to any one of <10> to <13>, which is an inorganic thin film.
<15> The inorganic structure according to any one of <10> to <14>, wherein a contact angle with water is 30 ° or more and a water drop falling angle is 40 ° or less.
<16> The inorganic structure according to any one of <11> to <15>, wherein an average value of the frictional force on the surface is lower than that before the steam treatment.
<17> The inorganic structure according to any one of <11> to <15>, wherein an average value of the frictional force on the surface is reduced to half or less than before the steam treatment.

<18> The inorganic structure according to any one of <10> to <17>, wherein the surface roughness (Ra) is 2 nm or less.
<19> A coating solution containing an inorganic oxide precursor is applied to form a film, which is then heat-treated at a temperature of 300 ° C. or higher, and further has a temperature of 30 ° C. or higher and 100 ° C. or lower and an absolute humidity of 15 g / m ^3. The inorganic structure according to any one of <10> to <18>, which is an inorganic thin film obtained by steam treatment in the above steam atmosphere.
<20> After film formation by a vacuum film formation method, heat treatment is performed at a temperature of 300 ° C. or higher, and further, treatment is performed in a steam atmosphere at a temperature of 30 ° C. or higher and 100 ° C. or lower and an absolute humidity of 15 g / m ³ or higher. The inorganic structure according to any one of <10> to <18>, which is a hafnia film obtained.
<21> The inorganic structure according to any one of <10> to <18>, which is a glass article.
<22> The inorganic structure according to any one of <10> to <18>, which is a metal article.
<23> After the glass article is heat-treated at a temperature of 100 ° C. or more and 500 ° C. or less, the glass article is further processed in a steam atmosphere at a temperature of 30 ° C. or more and 100 ° C. or less and an absolute humidity of 15 g / m ³ or more. <21> which is a glass article.

<24> A structure having a support and the inorganic structure according to any one of <10> to <20> covering all or part of the support.

<25> The steam treatment is performed by exposing the heat-treated coating film to a steam atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more. Production method.
<26> The steam treatment is performed by exposing the heat-treated coating film to a steam atmosphere having a product of a temperature (° C.) and a relative humidity (%) of 2000 ° C. ·% or more and 10,000 ° C. ·% or less. > Or <25> The method for producing an inorganic structure according to <25>.

<27> A film-forming process for forming a hafnia film on a support by a vacuum film-forming method, a heat-treating process for heat-treating the formed hafnia film at a temperature of 300 ° C. or higher, and steam-treating the heat-treated hafnia film And a water vapor treatment step for reducing a water drop falling angle of the heat-treated hafnia film.
<28> The steam treatment is performed by exposing the heat-treated hafnia film to a steam atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more. Production method.
<29> The steam treatment is performed by exposing the heat-treated hafnia film to a steam atmosphere having a product of a temperature (° C.) and a relative humidity (%) of 2000 ° C. ·% to 10,000 ° C. ·% <27 > Or <28> The method for producing an inorganic structure according to <28>.

<30> A heat treatment step in which a glass material is heat-treated at a temperature of 100 ° C. or more and 500 ° C. or less, and the heat-treated glass material is exposed to a steam atmosphere having a temperature of 30 ° C. or more and 100 ° C. or less and an absolute humidity of 15 g / m ³ or more. A steam treatment step for reducing a water droplet falling angle of the heat-treated glass material,
The manufacturing method of the glass article which has this.

<31> By subjecting the surface of the inorganic structure having reduced water slidability to a steam atmosphere having a temperature of 30 ° C. or more and 100 ° C. or less and an absolute humidity of 15 g / m ³ or more, steam treatment is performed. A method for recovering water slidability of an inorganic structure that recovers water.

According to the present invention, there are provided an inorganic structure having a surface excellent in water droplet removal property (slidability) and further excellent in durability, and a method for producing an inorganic structure capable of producing the inorganic structure. Can do.
Moreover, according to this invention, the manufacturing method of the inorganic thin film which can manufacture the inorganic thin film which has the surface excellent in water-drop removal property (sliding property) and was excellent also in durability can be provided.

It is a graph which shows the relationship between the density of a resistance point, and a water drop fall angle. An optical microscope showing the state of the vicinity of the rear end line of the water droplet (downstream with respect to the direction in which the water droplet slides) when the water droplet falls on the surface of the alumina film (water contact angle 41 °, the water droplet does not fall and spread) It is a photograph (magnification 3000 times). Sputter titania film (water contact angle 56 °, water droplet spreads without falling) Optical surface showing the state near the trailing edge of the water droplet (downstream with respect to the sliding direction) when the water droplet falls on the surface It is a microscope picture (magnification 3000 times). Optical showing the state of the vicinity of the trailing edge of the water droplet (downstream with respect to the direction in which the water droplet slides) when the water droplet falls on the surface of the alumina film (water contact angle 95 °, water droplet falling angle 26 °) after the steam treatment. It is a microscope picture (magnification 3000 times). It is a graph which shows the relationship between surface roughness (Ra) and water contact angle (degree). In FIG. 5, it is the graph which expanded and represented the range whose surface roughness (Ra) is 4 nm or less. It is a graph which shows the change of the water contact angle in a zirconia film | membrane. It is a graph which shows the change of the fall angle in a zirconia film. It is a XRD measurement result of a zirconia film | membrane. It is a graph which shows the change of the water contact angle in an alumina membrane. It is a graph which shows the change of the fall angle in an alumina film. It is an XRD measurement result of an alumina film | membrane.

It is a graph which shows a time-dependent change of the contact angle in a ceria film. It is a graph which shows the relationship between the water vapor processing time in a ceria film, and a contact angle. It is a graph which shows a time-dependent change of the fall angle in a ceria film. It is a graph which shows the relationship between the water vapor processing time in a ceria film, and a fall angle. It is a XRD measurement result of a ceria film. It is a graph which shows the change of the contact angle in a titania film | membrane. It is a graph which shows the change of the fall angle in a titania film. It is a graph which shows a time-dependent change of the contact angle in a hafnia film | membrane. It is a graph which shows the relationship between the water vapor processing time in a hafnia film | membrane, and a contact angle. It is a graph which shows a time-dependent change of the fall angle in a hafnia film | membrane. It is a graph which shows the relationship between the water vapor processing time in a hafnia film | membrane, and a fall angle. It is a XRD measurement result of the hafnia film | membrane formed into a film using 0.5M coating liquid. It is an XRD measurement result of the hafnia film | membrane formed into a film using 0.01M coating liquid. It is a graph which shows the change of the water contact angle in a blank (with water vapor treatment). It is a graph which shows the change of the water drop falling angle in a blank (with water vapor treatment). 6 is a graph showing a change in water contact angle in an alumina-titania film (with water vapor treatment). 6 is a graph showing a change in a water drop falling angle in an alumina-titania film (with water vapor treatment).

It is a graph which shows the evaluation result of photocatalytic activity about "Al-Ti 100: 1 40 degreeC 90%". It is a graph which shows the evaluation result of the photocatalytic activity about "Al-Ti 10: 1 40 degreeC 90%". It is a graph which shows the evaluation result of the photocatalytic activity about "Al-Ti 1: 1 40 degreeC 90%". It is a graph which shows the change of the water contact angle in a zirconia-titania film (with water vapor treatment). It is a graph which shows the change of the water drop falling angle in a zirconia-titania film (with water vapor treatment). 6 is a graph showing a change in water contact angle in a hafnia-titania film (with water vapor treatment). It is a graph which shows the change of the water droplet fall angle in a hafnia-titania film | membrane (with water vapor | steam processing). It is a graph which shows the change of the water contact angle in a titanium hydroxyapatite (TiHAP) film | membrane. It is a graph which shows the change of the water droplet fall angle in a titanium hydroxyapatite (TiHAP) film | membrane. It is a graph which shows the change of the water contact angle in the conditions of each water vapor | steam process about an alumina film | membrane. It is a graph which shows the change of the water contact angle in the conditions of each water vapor | steam process about a hafnia film | membrane. It is a graph which shows the change of the water contact angle with respect to the water vapor processing time when performing water vapor processing after room temperature environment storage. It is a graph which shows the change of the water drop falling angle with respect to the water vapor treatment time when performing water vapor treatment after room temperature environment storage.

It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor treatment time (elapsed time (day) in a water vapor atmosphere) in a glass substrate. It is a graph which shows the change of the water drop falling angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a glass substrate. It is a graph which shows the change of the water contact angle (degree) with respect to the elapsed time (days) in the dry atmosphere of a glass substrate. It is a graph which shows the change of the water drop fall angle (degree) with respect to the elapsed time (days) in the dry atmosphere of a glass substrate. It is a graph which shows the result of a traverse test in a glass substrate which performed steam treatment.

It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (Elapsed time (day) in a water vapor atmosphere) in an Ag polishing plate. It is a graph which shows the change of the water drop falling angle (degree) with respect to the water vapor processing time (Elapsed time (day) in a water vapor atmosphere) in an Ag polishing plate. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Cu polishing board. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Cu polishing board. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (Elapsed time (day) in a water vapor atmosphere) in an Al polishing plate. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (Elapsed time (day) in a water vapor atmosphere) in an Al polishing plate. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Ni polishing plate. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Ni polishing plate. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in an Fe polishing plate. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in an Fe polishing plate. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Ti polishing plate. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in a Ti polishing plate. It is a graph which shows the change of the water contact angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in Si wafer. It is a graph which shows the change of the water droplet fall angle (degree) with respect to the water vapor processing time (elapsed time (day) in a water vapor atmosphere) in Si wafer.

It is an XRD measurement result of a hafnia film (500 ° C.) and a hafnia film (asdepo) before heat treatment. It is a XRD measurement result of a hafnia film | membrane (1000 degreeC) and the hafnia film | membrane (asdepo) before heat processing. It is a graph which shows the change of the water contact angle in a hafnia film | membrane (500 degreeC). It is a graph which shows the change of the water drop falling angle in a hafnia film | membrane (500 degreeC). It is a graph which shows the change of the water contact angle in a hafnia film | membrane (1000 degreeC). It is a graph which shows the change of the water drop falling angle in a hafnia film | membrane (1000 degreeC). It is a schematic sectional drawing which shows notionally a mode that a water drop falls in the inorganic structure surface inclined with respect to the horizontal surface. FIG. 54B is a graph conceptually showing energy when the rear end surface of the water droplet moves from point A to point B in FIG. 54A. It is a schematic sectional drawing which shows notionally the mode of the surface of an inorganic structure in normal atmospheric environment conditions. It is a schematic sectional drawing which shows notionally the mode after performing a water vapor process with respect to the inorganic structure surface.

It is a graph showing the measurement results of the friction force of the alumina film _(Al 2 _{O 3).} Hafnia film is a graph showing the measurement results of the friction force (HfO _2). It is a graph which shows the measurement result of the frictional force of a quartz glass substrate (QG). It is a graph which shows the measurement result of the frictional force of a stainless steel substrate (SUS). It is a graph which shows the measurement result of the frictional force of the silicon wafer and sapphire glass which are not subjected to water vapor treatment. It is a graph which shows the relationship between the temperature of post-heat processing, a water contact angle (CA), and a water drop falling angle (SA) in soda-lime glass (SLG). In hafnia film (HfO _2), and the temperature of the post heat treatment, the water contact angle (CA) and water droplet sliding angle and (SA), is a graph showing the relationship.

It is a graph which shows the force which acts between a probe and the alumina membrane surface in the process which performed approach operation with respect to the alumina membrane surface before water vapor | steam processing. It is a graph which shows the force which acts between the probe and the alumina film surface in the process which performed the approach operation about the alumina film surface after water vapor treatment. It is a graph which shows the force which acts between a probe and the alumina membrane surface in the process of performing retraction operation | movement with respect to the alumina membrane surface before water vapor | steam processing. It is a graph which shows the force which acts between a probe and the alumina film surface in the process which performed the retraction operation | movement about the alumina film surface after a water vapor process. It is a graph which shows the force which acts between a probe and a sample surface in the process in which approach operation was performed about the hafnia film | membrane surface before water vapor | steam processing. It is a graph which shows the force which acts between a probe and a sample surface in the process which performed the approach operation about the hafnia film | membrane surface after a water vapor process. It is a graph which shows the change of the force which acts between a probe and a sample surface in the process which performed retraction operation about the hafnia film surface before water vapor treatment. It is a graph about the change of the force which acts between a probe and a sample surface in the process of performing retraction operation about the hafnia film surface after water vapor treatment.

4 shows FT-IR measurement results (wave number range: 400 cm ⁻¹ to 4000 cm ⁻¹ ) of a water sliding treatment sample using silica ultrafine particles and silica ultrafine particles before water sliding treatment. 4 shows FT-IR measurement results (wave number range: 1500 cm ⁻¹ to 1850 cm ⁻¹ ) of a water sliding treatment sample using silica ultrafine particles and silica ultrafine particles before water sliding treatment. It is a DTA / TG measurement result of the water slide treatment sample using silica ultrafine particles, and the silica ultrafine particles before water slide treatment.

≪Inorganic structure≫
In the inorganic structure of the present invention, the density of resistance points that inhibit the sliding of water droplets on the surface is 10 pieces / 30 mm ² or less.
Conventionally, inorganic materials centered on oxides have essentially higher surface energy than organics and often exhibit hydrophilicity, making it difficult to apply to applications that require water repellency (applications that dislike water). It has been thought that there is.
On the other hand, water repellent coating materials such as fluorine compounds have been known as organic substances. However, the water repellent coating material has a problem that it is difficult for water droplets to fall even when water is repelled, and it is difficult to remove water droplets. Thus, just because the water contact angle is high, the water drop falling angle is not necessarily low. Further, since the water-repellent coating material is organic, there is a problem that durability is low.
In the present invention, by setting the density of resistance points on the surface of the inorganic structure within the above range (that is, by reducing the number of singular points on the surface of the inorganic structure and improving the uniformity of the surface), It was completed on the basis of the novel finding that water droplet removal (slidability) can be improved.
Here, the water droplet removability (slidability) is a property determined by the size of a water droplet falling angle described later. The smaller the water drop falling angle, the better the water drop removability (slidability).
In addition, the inorganic structure of the present invention is superior in durability, wear resistance, and safety compared to an organic structure such as an organic film. In addition, the inorganic structure of the present invention can be a high-resistance inorganic structure, and in this case, the chargeability is also excellent.

The inorganic structure of the present invention may be in a thin film form (inorganic thin film form) or in a form other than a thin film form.
Here, the form of the inorganic thin film refers to the form of the inorganic thin film formed on a support (which may be organic or inorganic). In this case, the inorganic thin film surface has water slidability.
Hereinafter, the inorganic structure of the present invention in the form of an inorganic thin film may be referred to as “inorganic thin film of the present invention” or “inorganic thin film”. Specific examples of the inorganic thin film of the present invention will be described later.

Further, the forms other than the thin film form are solid forms of any shape such as a plate shape, a cylindrical shape, a film shape, a spherical shape, a cylindrical shape, a polyhedral shape, an indefinite shape, and can exist independently without a support. Refers to the solid form. In this case, the surface of the solid itself has water slidability.
Hereinafter, the inorganic structure of the present invention having a form other than a thin film may be referred to as “inorganic solid of the present invention” or “inorganic solid”. Specific examples of the inorganic solid of the present invention include glass articles and metal articles having the above shapes.

<Resistance point>
In the present invention, it is necessary that the density of resistance points that inhibit the sliding of water droplets on the surface of the inorganic structure is 10 pieces / 30 mm ² or less. In other words, the number of the resistance points per area of 30 mm ² needs to be 10 or less.
When the density of the resistance points exceeds 10/30 mm ² , the water drop falling angle increases, and the water drop removability deteriorates.

Here, “the density of the resistance points that inhibit the sliding of water droplets” refers to the value measured as follows.
First, a transparent glass stage tilted at an angle of 60 degrees with respect to a horizontal plane using a goniometer was prepared.
A glass substrate (sample) with an inorganic thin film was fixed on the transparent glass stage in such a direction that the surface on which the inorganic thin film was not formed and the surface of the transparent glass stage were in contact.
Next, water droplets having a mass of 50 mg were deposited on the inorganic thin film, and the state of the water droplets sliding down the surface of the inorganic thin film was observed. Observation was performed using a digital microscope VHX-1000 manufactured by Keyence Corporation at a magnification of 50 times (viewing range 5 mm × 6 mm) from a direction perpendicular to the surface of the inorganic thin film. At this time, a mirror was installed under the glass stage so that the illumination of the digital scope was reflected and the shape of the water drop was made to stand out.
The observation result was recorded as a moving image at a shutter speed of 15 fps. By closely observing the recorded moving image, the resistance point density was measured.
The density of resistance points on the surface of an inorganic structure (inorganic solid) other than the inorganic thin film can also be measured by observing a 50 mg mass of water droplets sliding down the surface inclined at 60 degrees with respect to the horizontal plane according to the above method.

FIG. 1 is a graph showing the relationship between resistance point density and water drop falling angle, measured for each film of zirconia, alumina, ceria, titania, hafnia, and silica.
The horizontal axis in FIG. 1 represents the density of resistance points (pieces / 30 mm ² ), that is, the number of resistance points per area of 30 mm ² on the logarithmic axis.
The vertical axis in FIG. 1 represents the water drop falling angle (°) as a linear axis.
As shown in FIG. 1, regardless of the type of film, 10/30 mm ² by weight, the water droplet falling angle is rapidly increased, if it is 10/30 mm ² or less water drop falling angle is confirmed to be reduced It was.

2, 3, and 4 are optical microscope photographs (magnification 3000 times) showing a state near the rear end of the water droplet (downstream side in the direction in which the water droplet slides) when the water droplet falls on the surface of the inorganic thin film. It is.
FIG. 2 is a photograph when an alumina film (a contact angle of 41 °, water droplets spread without wetting) is used as the inorganic thin film.
As shown in FIG. 2, when a water drop fell on the surface of this film, a resistance point was observed on the trailing edge of the water drop (arrow in FIG. 2). Further, the rear end line is not smooth and irregularities can be confirmed. Since the water contact angle is small, interference fringes can be confirmed in the water droplets.
FIG. 3 is a photograph when a sputtered titania film (contact angle 56 °, water droplets spread without falling) is used as the inorganic thin film.
As shown in FIG. 3, when a water drop fell on the surface of this film, a resistance point was observed on the trailing edge of the water drop (arrow in FIG. 3). Further, the rear end line is not smooth and irregularities can be confirmed.
FIG. 4 is a photograph when an alumina film (contact angle 95 °, water drop falling angle 26 °) after coating, baking, and steam treatment is used as the inorganic thin film.
As shown in FIG. 4, when a water droplet fell on the surface of this film, the trailing edge of the water droplet was smooth and no resistance point was observed.
As described above, since the phenomenon described with reference to FIGS. 1 to 4 is a phenomenon related to the surface state, it is presumed that the phenomenon can be observed not only on the surface of the inorganic thin film but also on the surface of the inorganic solid.

<Friction force and dynamic friction coefficient>
When the inorganic structure of the present invention having a resistance point density of 10 pieces / 30 mm ² or less is viewed from a viewpoint different from the resistance point density, Si ₃ having a thickness direction spring constant of 0.05 N / m. using N ₄ made of the cantilever, at the conditions of pressing pressure 14NN, region frictional force measured by the friction force microscope is equal to or less than 10 nN, and, _Si 3 _{N 4} thickness direction of the spring constant is 0.05 N / m Using a cantilever made of steel, the surface includes at least one of regions having a dynamic friction coefficient measured by a friction force microscope of 1.0 or less under a pressing pressure of 14 nN.
The inorganic structure includes at least one of a region where the frictional force is 10 nN or less and a region where the dynamic friction coefficient is 1.0 or less on the surface, thereby removing water droplets on the surface of the inorganic structure (sliding property). Will improve.

In the inorganic structure of the present invention, the average value of the frictional force on the surface is lower than that before the water vapor treatment (more preferably, it is lower than half before the water vapor treatment). Is preferred.
Here, the average value of the frictional force can be obtained, for example, as a mode value (peak value) of the frictional force at 256 measurement points × 256 measurement points.

<Water contact angle>
The inorganic structure of the present invention preferably has a water contact angle on the surface of 30 ° or more.
When the water contact angle is 30 ° or more, the surface energy of the inorganic structure can be further reduced, and adhesion of a fouling substance to the inorganic structure can be further suppressed. Further, when the water contact angle is 30 ° or more, when the inorganic structure is used for coating of glass, lenses, mirrors, etc., the visibility when water adheres becomes better.
In the present invention, the contact angle with respect to water (water contact angle) is measured by using a contact angle measuring device (Drop Master 500, Kyowa Interface Chemical Co., Ltd.) and dropping 3 mg of water (distilled water) on the surface of the inorganic structure. Refers to the value measured between 1 and 10 seconds.
The water contact angle is preferably 40 ° or more, more preferably 50 ° or more, and particularly preferably 60 ° or more from the viewpoint of surface energy and visibility.

Further, the inorganic structure of the present invention (including the case of an inorganic thin film containing titania described later) has a substantially reduced water contact angle even by light irradiation from the viewpoint of surface energy and visibility. Preferably not.
In the present invention, “substantially no decrease in water contact angle is observed even by light irradiation” means that the water contact angle of the inorganic structure does not substantially decrease even when irradiated with light (however, a decrease of about 10 °). Means allowed).
In addition, the inorganic structure of the present invention preferably has a water contact angle of 30 ° or more, more preferably 40 ° or more, still more preferably 50 ° or more, both before and after light irradiation. It is particularly preferable that the angle is at least.
In the present invention, “light irradiation” refers to irradiation with ultraviolet light (UV light) having a wavelength of 400 nm or less using a black light (FL10BL-B, National) at an intensity of 1 μW / cm ² to 5 mW / cm ^2. Refers to that.

<Water drop falling angle>
The inorganic structure of the present invention preferably has a water drop falling angle of 40 ° or less.
If the water drop falling angle is 40 ° or less, it is easier to remove the water drop by the inclination.
Here, the water drop falling angle refers to a value measured using a contact angle measuring device (Drop Master 500, Kyowa Interface Chemical Co., Ltd.) and a falling angle measuring device (SA-11, Kyowa Interface Chemical Co., Ltd.). Specifically, a camera attached to the contact angle measurement device while dropping 30 mg of water droplets on the surface of the inorganic structure and then tilting the surface of the inorganic structure with respect to a horizontal plane using the drop angle measurement device. Observe water drops from. The angle between the surface of the inorganic structure and the horizontal plane at the moment when the water droplet falls is measured, and this angle is taken as the water droplet falling angle. The moment of falling is the moment when both the front end point and the rear end point of the water droplet start to move.
In this specification, the water drop falling angle is a value of 0 ° or more and 90 ° or less. Even when the surface of the inorganic structure is tilted at 90 ° with respect to the horizontal plane, a drop angle of 90 ° is defined as a case where water drops do not fall.
The water drop falling angle is preferably 35 ° or less from the viewpoint of water drop removability.
As described above, a high water contact angle generally does not necessarily mean that the water drop falling angle is low, but the inorganic structure of the present invention has a remarkably low contact angle and forms droplets. If it becomes a water film without being dropped, the drop of water droplets may not be expected. Therefore, it is preferable to increase the water contact angle (for example, the water contact angle is 30 ° or more) to the extent that water droplets are formed.

<Surface roughness>
The inorganic structure of the present invention preferably has a surface roughness (Ra) of 2 nm or less.
Here, the surface roughness (Ra) refers to the arithmetic average roughness defined in JIS B0601 (1994).
The surface roughness (Ra) in the present invention refers to a value measured for a measuring range of 50 μm square using an AFM (atomic force microscope; VN-8000, manufactured by Keyence Corporation).
If the surface roughness (Ra) is 2 nm or less, the water contact angle can be further increased, and the water drop falling angle can be further decreased.
From the viewpoint of increasing the water contact angle and decreasing the water drop falling angle, the surface roughness (Ra) is preferably 1.6 nm or less, and more preferably 1.2 nm or less.

Moreover, the inorganic structure of the present invention preferably has a surface roughness (Rz) of 150 nm or less, more preferably 50 nm or less, from the viewpoint of increasing the water contact angle and decreasing the water drop falling angle. Here, the surface roughness (Rz) refers to a ten-point average roughness defined in JIS B0601 (1994).
The surface roughness (Rz) in the present invention refers to a value measured for a measuring range of 50 μm square using an AFM (atomic force microscope; VN-8000, manufactured by Keyence Corporation).

FIG. 5 is a graph showing the relationship between the surface roughness (Ra) and the water contact angle (°) measured for each film of zirconia, alumina, ceria, titania, hafnia, and silica.
FIG. 6 is a graph showing an enlarged view of the surface roughness (Ra) of 4 nm or less in FIG.
As shown in FIGS. 5 and 6, the water contact angle has a small change in the region of surface roughness (Ra) 2 nm to 350 nm, but increases rapidly in the region of 2 nm or less.

In addition, when the inorganic structure of the present invention is in the form of an inorganic thin film, the thickness of the inorganic thin film is not particularly limited, but is 10 μm or less from the viewpoint of obtaining the effect of the present invention more effectively. Preferably, it is 10 nm to 1000 nm.

<Material>
Although there is no limitation in particular as an inorganic structure of this invention, It is preferable that it is an inorganic structure containing a metal from a viewpoint which show | plays the effect of this invention more effectively.
In addition, the inorganic structure of the present invention may be an inorganic structure including at least one selected from metals, alloys, inorganic oxides, and glass from the viewpoint of more effectively achieving the effects of the present invention. preferable.
The inorganic structure of the present invention is more preferably a metal thin film, an inorganic oxide thin film, a metal solid, or an inorganic oxide solid, more preferably an inorganic oxide thin film or an inorganic oxide solid, A metal oxide thin film or a metal oxide solid is particularly preferable.

Here, the term “metal” refers to a metal element in a broad sense. In addition to a typical metal element (for example, Al), a transition metal element (for example, Cr, Au, Ti, Ag, Cu, Ni, Fe, etc.), Metal elements (for example, Si) are also included.

Moreover, as said alloy, the alloy containing 2 or more types of the said metal element is mentioned.
As the alloy, stainless steel (for example, stainless steel defined in JIS G4303-1998, JIS G4304-1999, or JIS G4305-1999) is preferable.
More specifically, examples of the stainless steel include SUS201, SUS202, SUS301, SUS302, SUS303, SUS304, SUS305, SUS316, SUS317, SUS329J1, SUS403, SUS405, SUS420, SUS430, SUS430LX, and SUS630.

The inorganic oxide is not particularly limited. Zirconium oxide (also referred to as “zirconia” or “ZrO ₂ ” in this specification), aluminum oxide (“alumina” or “Al ₂ O ₃ ” in this specification) ), Cerium oxide (also referred to herein as “ceria” or “CeO ₂ ”), titanium oxide (also referred to herein as “titania” or “TiO ₂ ”), hafnium oxide (in this specification) In this specification, “hafnia” and “HfO ₂ ”), silicon oxide (also referred to as “silica” and “SiO ₂ ” in the present specification), and the like can be given.
Here, the inorganic oxide thin film or the inorganic oxide solid may be a film (a simple film) or a solid (a simple solid) containing the inorganic oxide as a single component. It may be a film (a simple film) or a solid (a simple solid) contained above.

The inorganic oxide may be a complex oxide or a compound containing water in the structure, such as a clay mineral.
An example of the composite oxide is TiHAP (titanium-doped apatite) in which a part of Ca ions of apatite having a composition of Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ is substituted with Ti.

Also, examples of the glass include soda lime glass, Pyrex (registered trademark) glass, quartz glass, white plate glass, blue plate glass, non-alkali glass, and sapphire glass.

The inorganic structure of the present invention is composed of an inorganic substance as a main component, but may contain other components as long as the effects of the present invention are not hindered.

<Inorganic thin film>
The inorganic thin film of the present invention is preferably a film containing at least one selected from the group consisting of zirconia, alumina, ceria, hafnia, and silica from the viewpoint of increasing the contact angle and decreasing the falling angle. A film containing at least one kind from the group consisting of zirconia, alumina, and silica is more preferable.
Further, from the viewpoint of durability, a film containing at least one of hafnia and alumina is preferable.

The inorganic thin film of the present invention can also have photocatalytic activity.
The present inventors have developed a method of combining with a photocatalyst for the purpose of imparting self-cleaning properties to such an excellent water-sliding surface.
Conventionally, a self-cleaning technique using a photocatalyst has been widely used mainly on building outer walls. The principle is that by using the property of a semiconductor photocatalyst that exhibits hydrophilicity by light irradiation (hereinafter also referred to as “superhydrophilization”), the attached oily fouling component can be easily removed by rainfall or water washing. To do. This self-cleaning technique is a technique that enables the oily fouling component attached to be decomposed and removed by utilizing the property (organic substance decomposability) of a semiconductor photocatalyst that decomposes organic substances by light irradiation.
However, in the conventional self-cleaning technique, since the surface is hydrophilic, there are a problem that water is indispensable for removing the fouling component and a problem that fouling substances are inherently high because of high surface energy. In addition, since the surface is hydrophilic, it is difficult for water droplets to fall down (that is, the water slidability is inferior).

In this regard, a material that combines the above-mentioned surface with excellent water slidability and water droplet removal with a photocatalytic decomposition action, that is, a non-hydrophilic, non-hydrophilic photocatalyst has a surface with excellent self-cleaning properties that is difficult to adhere to dirt. It is an ideal surface.
The form which gave the photocatalytic activity to the inorganic thin film of this invention has such an ideal surface.

When the inorganic thin film of the present invention has photocatalytic activity, the inorganic thin film of the present invention is constituted as a simple film of titania, or titania and other materials (for example, zirconia, alumina, ceria, hafnia, silica) , Etc.).
That is, when the photocatalytic activity is imparted to the inorganic thin film of the present invention, it is a titania simple film, or at least one selected from the group consisting of titania and zirconia, alumina, ceria, hafnia, and silica. It is preferable that it is a composite film containing.
The composite film is preferably a titania-hafnia composite film, a titania-zirconia composite film, or a titania-alumina composite film.
The titania is preferably crystallized from the viewpoint of organic matter decomposability. The term “crystallization” as used in the present invention refers to a state in which there is a portion having crystallinity to the extent that it is judged to have crystallinity by X-ray structural analysis (that is, if the portion is amorphous, May be included). Whether or not titania has crystallized can also be confirmed by the presence or absence of organic matter decomposability.
In particular, when the inorganic thin film of the present invention contains crystallized titania, in addition to water repellency, water slidability, and durability, photocatalytic activity (particularly, organic matter decomposability) can be provided. For this reason, it becomes more suitable for uses such as a windshield of an automobile.
Examples of the crystallized titania include anatase type and rutile type. Among them, anatase type is preferable from the viewpoint of organic matter decomposability.

In general, titania often exhibits a phenomenon in which the water contact angle decreases due to light irradiation (superhydrophilic phenomenon; for example, the water contact angle may decrease by 10 ° or more). When titania is contained, as described above, it is preferable that the inorganic thin film does not show a significant decrease in water contact angle even when irradiated with light.

The inorganic thin film of the present invention described above is suitably produced by, for example, steaming after film formation.
The film formation is performed, for example, by heat-treating a coating film obtained by coating a coating solution containing an inorganic oxide precursor at a temperature of 300 ° C. or higher (hereinafter, this method is referred to as “sol-gel method”). Or after vacuum film formation such as sputtering or vapor deposition, if necessary, heat treatment is performed at a temperature of 300 ° C. or higher.
The water vapor atmosphere preferably has a temperature of 30 ° C. or higher and 100 ° C. or lower.
The water vapor atmosphere is preferably an atmosphere having an absolute humidity of 15 g / m ³ or more.
More preferably, the water vapor atmosphere is an atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more.
In the water vapor atmosphere, the product of temperature (° C.) and relative humidity (%) is preferably 2000 ° C. ·% or more and 10,000 ° C. ·% or less, and preferably 2500 ° C. ·% or more and 8000 ° C. ·% or less. It is more preferable that the temperature is 3000 ° C.% or more and 5000 ° C.% or less.

Details of the method for producing an inorganic thin film using steam treatment will be described later.

In particular, when the inorganic thin film of the present invention is a hafnia film, the hafnia film is formed by a vacuum film-forming method, heat-treated at a temperature of 300 ° C. or higher, and further processed in a steam atmosphere. It is also preferable.
Details of the method for manufacturing such a hafnia film will be described later.

<Inorganic solid>
Examples of the inorganic solid of the present invention include glass articles and metal articles.
As glass articles, glass articles of any shape using glass materials (for example, soda lime glass, Pyrex (registered trademark) glass, quartz glass, white plate glass, blue plate glass, non-alkali glass, sapphire glass, etc.) And glass articles that require water droplet removal.
As a specific example of such a glass article, as a member for vehicles (automobiles, etc.), window glass of houses, glass containers, white glass for solar cells, various display devices (liquid crystal display devices, organic EL display devices, etc.) Examples include alkali-free glass substrates, chemically tempered glass, and heat-resistant glass such as Pyrex (registered trademark) glass.
The glass article preferably has a high surface flatness (for example, a surface roughness Ra of 2 nm or less). For this purpose, a glass material having a mirror-polished surface or a float method is used. It is preferable to use a glass material.

The metal article is a metal article of any shape using a metal material (Cr, Au, Ti, Ag, Cu, Ni, Fe, Al, Si, etc.) or an alloy material (stainless steel, etc.), Examples include metal articles that require removability.
Specific examples of such metal articles include various pipes, metal containers, stainless steel plates for kitchens and bathrooms, aluminum outer wall materials for houses, aluminum plate materials for vehicles, and the like.
The metal article preferably has a high surface flatness (for example, a surface roughness Ra of 2 nm or less). For this purpose, it is preferable to use a metal material whose surface is polished into a mirror surface.

The inorganic solid (glass article or metal article) of the present invention described above is suitably produced by being treated in a steam atmosphere (that is, steam-treated) as described later.
The water vapor atmosphere is preferably an atmosphere having a temperature of 30 ° C. or higher and 100 ° C. or lower.
The water vapor atmosphere is preferably an atmosphere having an absolute humidity of 15 g / m ³ or more.
More preferably, the water vapor atmosphere is an atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more.
In the water vapor atmosphere, the product of temperature (° C.) and relative humidity (%) is preferably 2000 ° C. ·% or more and 10,000 ° C. ·% or less, and preferably 2500 ° C. ·% or more and 8000 ° C. ·% or less. It is more preferable that the temperature is 3000 ° C.% or more and 5000 ° C.% or less.

However, it is also preferable to treat the metal article in a steam atmosphere that satisfies at least one of the following (Condition 1) and (Condition 2).
(Condition 1) Temperature is 30 ° C. or higher and 120 ° C. or lower, and absolute humidity is 15 g / m ³ or higher.
(Condition 2) The product of temperature (° C.) and relative humidity (%) is 2000 ° C. ·% or more and 12000 ° C. ·% or less.

Moreover, in order to further improve the water droplet removal property, it is more preferable to perform a heat treatment at 100 ° C. or more and 500 ° C. or less before the steam treatment.

The inorganic structure (inorganic solid or inorganic thin film) of the present invention described above is an inorganic solid containing at least one selected from stainless steel, soda lime glass, and quartz glass, or zirconia, alumina, ceria, titania. , Hafnia, and an inorganic thin film containing at least one selected from the group consisting of silica are preferable.

<Steam treatment>
As described above, the inorganic structure (inorganic thin film and inorganic solid) of the present invention has remarkably uniform physical and chemical properties on the surface, and the number of resistance points is less than a certain level. Specifically, the density of resistance points that inhibit the sliding of water droplets on the surface is 10 pieces / 30 mm ² or less.
When the inorganic structure of the present invention is viewed from another viewpoint, the surface includes at least one of a region where the frictional force is 10 nN or less and a region where the dynamic friction coefficient is 1.0 or less.

As a specific method for obtaining the inorganic structure of the present invention, treatment in a steam atmosphere (steam treatment) is effective.
The steam treatment can be performed, for example, by exposing an inorganic structure before the steam treatment (hereinafter also referred to as “inorganic structure material”) in a steam atmosphere.

The steam treatment can also be performed by spraying steam on the surface of the inorganic structure material.
Here, as a method of spraying water vapor, a method of spraying water vapor of about 50 ° C. to 100 ° C. from a nozzle or the like can be mentioned.
The spraying time at this time varies depending on the state of the inorganic structure material to be subjected to the steam treatment and the environment in which the inorganic structure material is placed, but can be, for example, several minutes to 10 hours.
The structure of the nozzle is desirably a structure capable of exposing a large area as much as possible to water vapor at a time. For example, the nozzle has a porous filter facing the surface to be treated of the inorganic structure material, and the inorganic filter is made of the inorganic filter. A structure capable of supplying water vapor from the side opposite to the side where the structure material exists is desirable.

Hereinafter, the reason (mechanism) that the density of the resistance points is caused by the steam treatment will be described. However, the present invention is not limited by the following reason (mechanism).

Conventionally, optimization of film forming conditions and heat treatment conditions has been considered effective for imparting water droplet removal properties to inorganic structures (inorganic thin films and inorganic solids). Thus, it was revealed that the steam treatment is effective.
Conventionally, steam treatment has been thought to increase the affinity between the surface and water (ie, reduce the contact angle and increase the falling angle) by increasing the amount of hydroxyl groups on the oxide surface.
However, as a result of actual examination, it has become clear that the contact angle is increased by the steam treatment, the falling angle is decreased, and the water drop removability is improved. This finding is a discovery that has never been known so far, and is extremely important for imparting a high level of water slidability to an inorganic structure.
The detailed mechanism of this is the subject of future research, but it is thought that the physical and chemical uniformity, which seems to affect the receding contact angle of the water droplets described at the beginning, is improved by the steam treatment. In order to investigate the details of this mechanism, the FT-IR measurement and the TG / DTA measurement were performed by subjecting the ultrafine silica particles to water vapor treatment under the condition that the water slidability was developed.

<FT-TR measurement and DTA / TG measurement>
A sliding water sample (powder) using the following ultrafine silica particles was prepared, and FT-TR measurement and DTA / TG measurement were performed on the sliding water sample (powder).
Note that the conditions not described in this experimental example (FT-TR measurement and DTA / TG measurement for the water slide sample (powder)) are the same as those in Experimental Example 1 described later.

(Preparation of water-sliding samples using silica ultrafine particles)
10 g of silica ultrafine particles (AEROSIL 200 manufactured by Nippon Aerosil Co., Ltd.) was treated (sliding water treatment) for 4 days (96 hours) in a steam atmosphere at a temperature of 90 ° C. and a relative humidity of 50% to obtain a sliding water sample.

(FT-IR measurement)
The FT-IR measurement was performed on the sliding water treated sample obtained above under the following measurement conditions.
As a comparative control, FT-IR measurement was performed in the same manner for the ultrafine silica particles before the above-mentioned water sliding treatment.

~ FT-IR measurement conditions ~
・ Device: FTIR-8600PC (manufactured by Shimadzu Corporation)
・ Measurement method: Transmission method (KBr pellet)
・ Dilution rate: 1% by mass
Measurement wave number range: 400 cm ⁻¹ to 4000 cm ⁻¹
・ Resolution: 4cm ^-1
・ Number of integration: 40 times ・ Apotize function: Happ-Genzel function

FIG. 72 shows the results of FT-IR measurement (wave number range 400 cm ⁻¹ to 4000 cm ⁻¹ ) of the slidable sample using silica ultrafine particles and the ultrafine silica particles before the slidable water treatment.
FIG. 73 shows FT-IR measurement results (wave number range: 1500 cm ⁻¹ to 1850 cm ⁻¹ ) of a water slide treatment sample using silica ultrafine particles and silica ultrafine particles before water slide treatment. Specifically, FIG. 73, of the FT-IR measurement results of FIG. 72 is a diagram showing an enlarged part in the wave number range ^1500cm ^-1 ~ ^1850cm -1.
72 and 73, the waveform of “Tre.” Is the FT-IR measurement result of the water slide treatment sample, and the waveform of “Pre.” Is the FT-IR measurement result of the silica ultrafine particles before the water slide treatment. .

As shown in FIG. 72 and FIG. 73, a new peak that did not exist in the ultrafine silica particles (Pre.) Before the water slide treatment appeared at 1700 cm ⁻¹ in the water slide sample (Tre.).
There was no other noticeable difference between the water slide sample (Tre.) And the ultrafine silica particles (Pre.) Before the water slide treatment. The peak at 1630 cm ⁻¹ common to both is the bending vibration of liquid water molecules. Further, the peak in the vicinity of 3400 cm ⁻¹ common to both is the OH stretching vibration of liquid water molecules.
On the other hand, it was confirmed that the peak at 1700 cm ⁻¹ seen in the water-sliding sample (Tre.) Was not present in liquid water but was present in ice clusters (The Journal of Physical Chemistry, March 1993). , Vol97, Issue 11, pp.2485-2487).
The above results suggest that the water condition on the silica surface is greatly changed by the water sliding treatment, and water clusters having a special structure are formed.

(DTA / TG measurement)
The DTA / TG measurement (differential thermal-thermogravimetric simultaneous measurement) was performed on the sliding water treated sample obtained above under the following measurement conditions.
As a comparative control, DTA / TG measurement was performed in the same manner for the silica ultrafine particles before the water sliding treatment.

~ DTA / TG measurement conditions ~
・ Device: TG-8120 (manufactured by Rigaku Corporation)
・ Measurement range: Room temperature to 1000 ℃
・ Atmosphere: Air (50mL / min.)
・ Sample amount: 7-8mg
Reference sample: α-Al ₂ O ₃
・ Sample pan: Pt

FIG. 74 shows the DTA / TG measurement results of the water sliding treatment sample using the silica ultrafine particles and the silica ultrafine particles before the water sliding treatment.
In FIG. 74, the “Tre.” Waveform is the DTA / TG measurement result of the water slide treatment sample, and the “Pre.” Waveform is the DTA / TG measurement result of the silica ultrafine particles before the water slide treatment.

As shown in FIG. 74, in the silica ultrafine particles (Pre.) Before the water sliding treatment, the mass rapidly decreased in the range of about 100 ° C. or lower, and almost no decrease in mass was observed at about 100 ° C. or higher. As described above, most of the water was lost by about 100 ° C. in the ultrafine silica particles (Pre.) Before the water sliding treatment. Silica ultrafine particles (fumed silica) are produced in a high-temperature flame and are considered to have few OH groups, so this result is acceptable to some extent.
On the other hand, in the water slide sample (Tre.), The amount of mass decrease was small in the range of about 100 ° C. or less, and the sample decreased gradually even in the range of 200 ° C. or more.
However, the silica ultrafine particles (Pre.) Before the water sliding treatment and the water sliding treatment sample (Tre.) Did not show a large difference in the amount of mass reduction when the temperature was raised to 1000 ° C.
Further, in the slidable water treatment sample (Tre.), No mass reduction or exothermic peak that was thought to be due to the combustion of organic substances was observed.
The above results suggest that the water state on the silica surface is greatly changed by the water sliding treatment.

Considering the results of the FT-IR measurement and the DTA / TG measurement together, the water slidability in the present invention is caused by the formation of water clusters having a special structure on the surface by the steam treatment. It is inferred that Although this cluster contains water molecules, it forms a surface that is relatively thermally stable and difficult to wet liquid water. It is not clear whether this water cluster itself has a small wettability to liquid water or whether it exerts water repellency by affecting the properties of organic substances adsorbed on this cluster. In addition, this cluster is relatively stable thermally and has a stable structure. Physical non-uniformity that causes the activation energy required to peel off the rear end face of water droplets by covering the surface of inorganic structures (inorganic thin films and inorganic articles) with water clusters having this special structure That is, it is considered that there is a property of eliminating physical non-uniformity that causes a decrease in dynamic wettability.

For example, as shown in FIG. 54A, when the water droplet falls on the surface of the inorganic structure inclined with respect to the horizontal plane, the rear end surface of the water droplet peels off from the point A and moves to a point B lower than the point A. In FIG. 54A, water drops before falling are indicated by solid lines, and water drops after falling are indicated by broken lines.
At this time, as shown in FIG. 54B, the barrier of the activation energy EA needs to be exceeded. When the point A is a chemically and physically non-uniform point, the activation energy EA increases.

FIG. 55 is a schematic cross-sectional view conceptually showing the state of the surface of the inorganic structure under normal atmospheric environment conditions, and FIG. 56 is a conceptual view of the state after the steam treatment is performed on the surface of the inorganic structure. It is a schematic sectional drawing shown.
As shown in FIG. 55, under normal atmospheric environment conditions, —OH groups exist on the surface of the inorganic structure, water molecules (H ₂ O) are adsorbed thereon, and organic matter R is adsorbed thereon. Yes. The surface of the inorganic structure is slightly hydrophobic due to the presence of the organic substance R. Here, if the adsorbed state is non-uniform and there is a resistance point, it is considered that the activation energy described above increases and the dynamic water repellency decreases.
When such a surface is subjected to water vapor treatment, as shown in FIG. 56, organic substances on the surface are once removed, and uniform and uniform OH groups are generated, on which H ₂ O having a special structure is formed. Clusters are formed. At this time, in order to further improve the organic matter removability on the surface, it is more preferable to perform heat treatment (for example, heat treatment at 100 ° C. or higher) before the steam treatment.
Next, the organic substance R is adsorbed with good uniformity on the H ₂ O cluster having a special structure, and the surface on which the organic substance R adheres with good uniformity is constructed (FIG. 56), so that dynamic water repellency A surface with a high and relatively high contact angle is constructed.
Since the water clusters formed after the steam treatment are thermally relatively stable, they are strongly bonded, so they are bonded to the inorganic structure together with the organic substance R adsorbed thereon. Can be estimated. The surface thus produced does not deteriorate in dynamic water repellency even when subjected to a mechanical durability test such as friction. Further, in the case of slight deterioration such as peeling of the organic substance R on the surface, the organic substance R is immediately re-adsorbed and the dynamic water repellency is restored.

As described above, organic matter is present on the surface both when left in an atmospheric environment and when subjected to steam treatment.
Therefore, there is not always a correlation between the amount of organic matter and dynamic water repellency (water drop falling angle), and just because there is a lot of organic matter on the surface does not necessarily mean that the dynamic water repellency is high.
Hereinafter, an experiment regarding the correlation between the amount of organic matter (carbon amount), the water contact angle, and the water drop falling angle performed by the present inventors regarding the above contents will be described.
Table 1 below shows the results of investigating the correlation between the amount of organic matter (carbon content), the contact angle, and the water drop falling angle.

Samples A, B-1, and B-2 are all alumina films formed on a glass substrate. Specifically, an alumina coating solution (0.1 M) described later is applied to a glass substrate (Corning “Corning 1737”) with a spin coater at 1500 rpm for 10 seconds and dried at 120 ° C. for 30 minutes. Subsequently, it is an alumina film obtained by baking at 500 ° C. for 30 minutes (other detailed conditions are the same as those in Experimental Example 1 described later).
Sample A is a sample obtained by leaving the above-obtained alumina film for 3120 hours (130 days) in a steam atmosphere at a temperature of 40 ° C. and a relative humidity of 95% (that is, subjected to steam treatment).
Sample B-1 is a sample obtained by leaving the alumina film obtained above for 1440 hours (60 days) in a sealed case.
Sample B-2 is a sample obtained by leaving the alumina film obtained above for 2880 hours (120 days) in an atmospheric environment (temperature 25 ° C., relative humidity 55%).
As a result of XRD measurement, all of the above samples have been confirmed to be amorphous. Moreover, it has confirmed that the surface roughness of all the above samples is controlled to several nanometers or less.

The column of carbon content in Table 1 is the result of measuring the carbon content of each of the samples A, B-1, and B-2 using X-ray photoelectron spectroscopy (XPS). The columns of water contact angle and water drop falling angle are the results of measuring the water contact angle and water drop falling angle of each of Samples A, B-1, and B-2 by the method described above.

As shown in Table 1, in Sample A and Sample B-2, the amount of carbon is increased due to adhesion of organic substances on the surface, and the water contact angle is increased.
However, in Sample B-2 which was simply left in the atmospheric environment, water droplets did not fall, whereas in Sample A subjected to the steam treatment, the water droplet fall angle was very low.
As described above, there is not always a correlation between the amount of organic matter and dynamic water repellency (water drop falling angle).
Therefore, it has been confirmed that it is important to keep the density of the resistance points on the surface below a certain level by water vapor treatment or the like for dynamic water repellency expression (reduction of the water drop falling angle).

<Preferable conditions for steam treatment>
Next, preferable conditions for the water vapor treatment for more effectively obtaining the effect of dynamic water repellency expression (reduction of water drop falling angle) will be described.
The water vapor atmosphere in the water vapor treatment is preferably at a temperature of 30 ° C. or higher and 100 ° C. or lower from the viewpoint of more effectively obtaining lubricity (reducing the water drop falling angle).
Furthermore, the temperature is more preferably 40 ° C. or higher and 100 ° C. or lower, further preferably 50 ° C. or higher and 100 ° C. or lower, and particularly preferably 80 ° C. or higher and 100 ° C. or lower.
Further, the water vapor atmosphere is preferably an atmosphere having an absolute humidity of 15 g / m ³ or more from the viewpoint of imparting lubricity. Furthermore, an atmosphere with an absolute humidity of 15 g / m ³ or more and 300 g / m ³ or less is preferable, an atmosphere with an absolute humidity of 15 g / m ³ or more and 200 g / m ³ or less is more preferable, and an absolute humidity of 15 g / m ³ or more and 130 g / m ³ or less. And an atmosphere with an absolute humidity of 50 g / m ³ or more and 130 g / m ³ or less is particularly preferable.
A particularly preferable water vapor atmosphere is an atmosphere satisfying both the temperature range and the absolute humidity range (for example, an atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m ³ or more).

Further, the water vapor atmosphere has a product of temperature (° C.) and relative humidity (%) of 2000 ° C. ·% or more and 10000 ° C. from the viewpoint of more effectively obtaining the effect of improving the water slidability (reducing the water drop falling angle). It is preferably% or less, more preferably 2500 ° C. ·% or more and 8000 ° C. ·% or less, and particularly preferably 3000 ° C. ·% or more and 5000 ° C. ·% or less.
When the product of the temperature (° C.) and the relative humidity (%) in the water vapor atmosphere is 2500 ° C. ·% or more and 8000 ° C. ·% or less, the effect of improving the lubricity can be obtained more effectively. The long-term stability is also improved.

In addition, when the inorganic structure is a metal article, it is also preferably a water vapor atmosphere that satisfies at least one of the following (Condition 1) and (Condition 2).
(Condition 1) Temperature is 30 ° C. or higher and 120 ° C. or lower, and absolute humidity is 15 g / m ³ or higher.
(Condition 2) The product of temperature (° C.) and relative humidity (%) is 2000 ° C. ·% or more and 12000 ° C. ·% or less.

Moreover, although the time of water vapor | steam processing changes also with the kind of inorganic structure, 1 hour or more is preferable, 3 hours or more are more preferable, 1 day (24 hours) or more are more preferable, and 3 days (72 hours) or more are preferable. More preferred is 10 days (240 hours) or longer.

The steam treatment can be performed using a known constant temperature and humidity chamber.
Examples of such a constant temperature and humidity chamber include HUMIDIC CHAMBER IG420, HUMIDIC CHAMBER IW222, HUMIDIC CHAMBER IH400 (manufactured by Yamato Scientific Co., Ltd.), and the like.

<Pretreatment>
As a specific method for obtaining the inorganic structure (inorganic thin film and inorganic solid) of the present invention, an organic substance attached to the surface of the inorganic structure material (inorganic structure before being subjected to the water vapor treatment) is more efficient. From the viewpoint of removal, it is also effective to perform a pretreatment for removing the organic matter on the surface of the inorganic structure material before the steam treatment.
The pretreatment is not particularly limited as long as it is a treatment that removes at least part of the organic substances present on the surface of the inorganic structure material. For example, heat treatment, washing treatment (ultrasonic washing treatment, pure water washing treatment) , Cleaning treatment using a cleaning liquid, and the like), and ultraviolet irradiation treatment.
Among these, the pretreatment is preferably at least one of heat treatment, ultrasonic cleaning treatment, and ultraviolet irradiation treatment.

(Heat treatment)
The temperature of the heat treatment is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, from the viewpoint of organic substance removability.
Furthermore, when the inorganic structure of the present invention is in the form of an inorganic thin film by a sol-gel method, the temperature of the heat treatment is more preferably 300 ° C. or higher from the viewpoint of firing the coating film.
In addition, when the inorganic structure of the present invention is in the form of an inorganic thin film formed by a vacuum film forming method, the temperature of the heat treatment is more preferably 300 ° C. or higher from the viewpoint of crystallization.

The upper limit of the heat treatment temperature is not particularly limited as long as the temperature is lower than the softening point of the heat treatment target. Here, when the inorganic structure of the present invention is in the form of an inorganic thin film, the “softening point of the object to be heat-treated” refers to the lower one of the softening point of the inorganic thin film and the softening point of the support. When the inorganic structure of the present invention is in the form of an inorganic solid, it indicates the softening point of the inorganic solid.
The upper limit of the heat treatment temperature varies depending on the object of heat treatment, but may be 1200 ° C., for example.

The heat treatment time varies depending on the temperature, but is preferably 0.5 to 3 hours, more preferably 0.5 to 1 hour.
The heat treatment can be performed in a known furnace such as a muffle furnace.
If necessary, the inorganic structure after the heat treatment is cooled to 30 ° C. or more and 100 ° C. or less, and then subjected to the steam treatment described above. The cooling can be performed, for example, by cooling (furnace cooling) for 3 to 6 hours in the furnace used for the heat treatment.

The atmosphere in which the heat treatment is performed is not particularly limited, but for example, from the viewpoint of more effectively suppressing an increase in surface roughness due to surface oxidation, it is preferably performed in a poor oxygen atmosphere (for example, in a nitrogen atmosphere). .

(Ultrasonic cleaning process)
A known method can be used as the method of the ultrasonic cleaning treatment.
The ultrasonic cleaning treatment can be performed using, for example, a known ultrasonic cleaning apparatus.
The condition of the ultrasonic cleaning treatment is not particularly limited as long as at least a part of the organic substance existing on the surface of the inorganic structure material can be removed, but preferable conditions include, for example, 10 minutes or more in pure water. The conditions which carry out an ultrasonic cleaning process can be mentioned.

(UV irradiation treatment)
As the ultraviolet irradiation treatment, a known method can be used.
In the ultraviolet irradiation treatment, the ultraviolet ray to be irradiated is not particularly limited as long as it is an ultraviolet ray that can remove at least a part of the organic substance existing on the surface of the inorganic structure material. For example, excimer light (for example, excimer light generated from ArF, XrF, XrCl, XeCl, Ar ₂ , Xr ₂ , etc.) can be used.
The intensity of the irradiated ultraviolet light is preferably 10 mW / cm ² to 40 mW / cm ² .
The irradiation time is preferably 300 seconds to 720 seconds, and more preferably 600 seconds to 720 seconds.
As the method of ultraviolet irradiation treatment, a method of directly irradiating an ultraviolet lamp such as an excimer lamp or a known ultraviolet irradiation treatment apparatus (UV treatment apparatus, UV surface modification apparatus, UV cleaning apparatus, etc.) is used. The method to perform is mentioned.

<Post-processing>
As a specific method for obtaining the inorganic structure (inorganic thin film and inorganic solid) of the present invention, from the viewpoint of stabilizing the properties of the water-slidable surface obtained by the steam treatment, after the steam treatment step, It is preferable to heat-treat the inorganic structure material as a post-treatment.
The temperature of the heat treatment is preferably a steam treatment temperature (temperature of the steam atmosphere) or more and 300 ° C. or less, and more preferably 100 ° C. or more and 300 ° C. or less.
The preferable conditions and preferable methods in the heat treatment as the post-treatment are the same as the preferable conditions and methods in the heat treatment as the pretreatment.

≪Structure≫
The structure of the present invention is constituted by being entirely or partially covered with the inorganic thin film of the present invention.
In the structure of the present invention, the support coated with the inorganic thin film is not particularly limited, and may be organic or inorganic.
As the support, specifically, glass (for example, soda lime glass, Pyrex (registered trademark) glass, quartz glass, white plate glass, blue plate glass, non-alkali glass, sapphire glass, etc.), metal, plastic, resin, Various materials such as ceramics, semiconductors, crystals, paper, and wood can be used without particular limitation, but glass and ceramics are preferable, and glass is particularly preferable from the viewpoint of obtaining the effects of the present invention more effectively. The support may be used as it is, or a support on which a silica (SiO ₂ ) film or the like is formed may be used.

Since the structure of the present invention is covered with an inorganic thin film having water drop removal property and durability, it is suitable for, for example, applications where water adhesion and intrusion are hated.
In addition, since the inorganic thin film is excellent in various performances such as safety, chargeability, durability, and abrasion resistance, it is also suitable as an alternative material for the fluorine-based organic water repellent material.
Specific examples of such applications include front windows of automobiles, residential glass with anti-condensation functions, water-circulating members and building materials such as kitchens and bathrooms, tanks and reactors used in manufacturing processes such as chemical solutions and food solutions, Examples include piping inner surfaces, stirring tanks and stirrers, cooking utensils such as frying pans with excellent durability, measuring instrument inner surfaces, coating rolls, and the like.
In particular, when the inorganic thin film is a film containing titania, it can be used as a self-cleaning member that is excellent in water droplet removal and that oxidatively decomposes remaining contaminants by photocatalysis.

≪Method for producing inorganic structure≫
The method for producing an inorganic structure of the present invention includes a step of preparing an inorganic structure material (hereinafter, “inorganic structure material preparation step”) and a steam treatment step of steam-treating the inorganic structure material.
According to the method for producing an inorganic structure of the present invention, it is possible to produce an inorganic structure having a surface excellent in water droplet removal property and further excellent in durability.
Moreover, according to the manufacturing method of the inorganic structure of this invention, it is easy to adjust the density of the said resistance point in the inorganic structure surface manufactured to 10 piece / 30mm < ² > or less.
In addition, according to the method for manufacturing an inorganic structure of the present invention, an inorganic structure including at least one of a region where the frictional force is 10 nN or less and a region where the dynamic friction coefficient is 1.0 or less is manufactured on the surface. Easy to do.
The manufacturing method of the inorganic structure of this invention may have another process as needed.

<Inorganic structure material preparation process>
The inorganic structure material preparation step is a step of preparing an inorganic structure material to be subjected to steam treatment.
Here, the “inorganic structure material” refers to an inorganic structure before being subjected to the water vapor treatment in the water vapor treatment step. Therefore, the “inorganic structure material” may be the same as the manufactured inorganic structure (inorganic structure after being subjected to the treatment of the water vapor treatment step) in appearance.
The inorganic structure material to be prepared is not particularly limited, but from the viewpoint of more effectively obtaining the effect of improving the water slidability by the water vapor treatment, an inorganic structure material having a small amount of organic matter attached to the surface is preferable.
Examples of inorganic structure materials that have a small amount of organic matter on the surface include inorganic structure materials (glass materials, metal materials, etc.) that have not passed much time since manufacture, and inorganic materials that have a short storage time in the atmosphere since manufacture. Examples include structural materials (glass materials, metal materials, etc.).
In addition, as the inorganic structure material to be prepared, it is also preferable to prepare an inorganic structure material that has been subjected to pretreatment for removing organic substances on the surface in advance.

Moreover, as an inorganic structure material to be prepared, an inorganic structure having a smooth surface (for example, having a surface roughness (Ra) of 2 nm or less) from the viewpoint of more effectively obtaining the effect of improving water slidability by water vapor treatment. A material is preferred.
In addition, as the inorganic structure material to be prepared, an inorganic structure material that has been subjected to a polishing process in which the surface is polished in advance (for example, the surface roughness (Ra) is 2 nm or less) is also preferable.

<Steam treatment process>
The water vapor treatment step is a step of reducing the water droplet falling angle on the surface of the inorganic structure material by subjecting the inorganic structure material to water vapor treatment.
In the steam treatment step, the water droplet falling angle on the surface of the inorganic structure material is preferably reduced by 10 ° or more, more preferably by 20 ° C. or more, and particularly preferably by 30 ° or more.
The preferable range of the water vapor treatment in the water vapor treatment step is as described in the section <Steam treatment> and <Preferred conditions for water vapor treatment> in the << inorganic structure >>.

<Pretreatment process>
Moreover, the manufacturing method of the inorganic structure of this invention has the pre-processing process which performs the pre-processing which removes the organic substance on the surface of this inorganic structure raw material with respect to the said inorganic structural raw material before the said water vapor treatment process. It is preferable.
By having this pretreatment process, the effect of water sliding by steam treatment can be obtained more effectively.
The preferable range of the pretreatment in the pretreatment step is as described in the section <Pretreatment> in the << inorganic structure >>.

<Post-processing process>
Moreover, the manufacturing method of the inorganic structure of this invention has the post-processing process which performs the heat processing more than the temperature of the said water vapor | steam 300 degreeC or less as a post-process with respect to the said inorganic structure raw material after the said water vapor treatment process. Is preferred.
By having this post-treatment step, the properties of the water-slidable surface obtained by the steam treatment can be further stabilized.
The preferable range of the post-treatment in the post-treatment step is as described in the section of <Post-treatment> in the << inorganic structure >>.

Next, as a more specific form of the method for manufacturing an inorganic structure, a method for manufacturing an inorganic thin film, a method for manufacturing a glass article, and a method for recovering the water slidability of the inorganic structure will be described.

≪Inorganic thin film manufacturing method≫
In the method for producing an inorganic thin film of the present invention, a coating solution containing an inorganic oxide precursor is coated on a support to form a smooth coating film (for example, having a surface roughness (Ra) of 2 nm or less). A film forming step, a heat treatment step of heat-treating the formed coating film at a temperature of 300 ° C. or higher, and a steam treatment step of steam-treating the heat-treated coating film.
According to the method for producing an inorganic thin film of the present invention, it is possible to produce an inorganic thin film having a surface excellent in water droplet removability and further excellent in durability.
Moreover, according to the manufacturing method of the said inorganic thin film of this invention, it is easy to adjust the density of the said resistance point in the inorganic structure surface manufactured to 10 pieces / 30mm < ² > or less.
In addition, according to the method for producing an inorganic thin film of the present invention, an inorganic thin film including at least one of a region where the frictional force is 10 nN or less and a region where the dynamic friction coefficient is 1.0 or less is produced on the surface. easy.
The method for producing an inorganic thin film of the present invention is a form of a method for producing an inorganic thin film using a sol-gel method.
The method for producing an inorganic thin film of the present invention may further include other steps as necessary.

<Coating film formation process>
The coating film forming step is a step of forming a coating film by applying a coating liquid containing an inorganic oxide precursor onto a support (and drying it as necessary).

(Support)
The support is not particularly limited, and for example, the same support as that described in the section of “Structure” can be used.

(Coating liquid containing inorganic oxide precursor)
The coating liquid containing the inorganic oxide precursor (hereinafter also referred to as “coating liquid”) may be prepared or may be prepared in advance, such as a commercial product.
Here, the precursor of an inorganic oxide refers to a substance that becomes an inorganic oxide by heating, and examples thereof include metal salts and metal alkoxides.
Examples of the inorganic oxide include metal oxides (zirconia, alumina, ceria, titania, hafnia, silica, etc.).

The coating liquid containing the inorganic oxide precursor is preferably a coating liquid containing a solvent and a metal salt (or a hydrate of the metal salt) or a metal alkoxide.
The coating solution may further contain a chelating agent as necessary.
As the metal salt, for example, nitrate, acetate, hydrochloride, sulfate and the like are suitable.

Specific examples of inorganic oxide precursors are given below, but the present invention is not limited to the following specific examples.

Examples of zirconia precursors include zirconium halides (eg, zirconium chloride oxide octahydrate, zirconium tetrachloride, zirconium tetrafluoride, zirconium tetrabromide, zirconium tetraiodide, zirconium tribromide, three Zirconium fluoride monochloride, zirconium tribromide monoiodide, zirconium triiodide monofluoride, zirconium dibromide, zirconium difluoride dichloride, zirconium dibromide diiodide, zirconium diiodide dichloride ), Zirconium inorganic acid salts (for example, zirconium oxychloride / octahydrate, zirconium oxynitrate / dihydrate, zirconium nitrate / tetrahydrate, etc.), zirconium organic acid salts (for example, zirconium acetate, Etc.), zirconium alkoxide (eg, zirconium tetramethoxide, zirconium) Nium tetraethoxide, zirconium tetraisopropoxide, zirconium tetra n-butoxide, zirconium tetrapentoxide, etc .; preferably an alkoxide having 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms), a zirconium complex (for example, zirconium Acetylacetonate, etc.).
Among these, zirconium alkoxide is preferable, and zirconium tetraisopropoxide is more preferable.
Examples of commercially available zirconia precursors include Zr-05-P (High Purity Chemical Research Laboratory).

Examples of the alumina precursor include aluminum inorganic acid salt (for example, aluminum nitrate nonahydrate).

Examples of the ceria precursor include cerium inorganic acid salts (for example, cerium nitrate hexahydrate).

Examples of titania precursors include, for example, organic titanium compounds, titanium alkoxides (eg, tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium, etc.), titanium chelates, titanium Examples thereof include acetate, and examples of the inorganic titanium compound include TiCl ₄ and Ti (SO ₄ ) ₂ .
Of these, titanium alkoxide is preferable, and titanium tetraisopropoxide is more preferable.
Examples of commercially available titania precursors include NDH-510C (manufactured by Nippon Soda Co., Ltd.).

Hafnia precursors include, for example, hafnium halides (eg, hafnium tetrachloride, hafnium tetrafluoride, hafnium tetrabromide, hafnium tetraiodide, hafnium tribromide trichloride, hafnium trifluoride tribromide, triodor Hafnium monochloride, hafnium triiodide monochloride, hafnium dibromide dichloride, hafnium dibromide dibromide, hafnium dibromide diiodide, hafnium diiodide diiodide, etc.), hafnium inorganic acid salt (For example, hafnium nitrate, etc.), hafnium alkoxide (for example, hafnium tetramethoxide, hafnium tetraisopropoxide, etc.), and a hafnium complex (for example, hafnium acetylacetonate, etc.).
Among these, hafnium alkoxide is preferable, and hafnium tetraisopropoxide is more preferable.
As a commercial product of the precursor of hafnia, for example, Hf-05 (High Purity Chemical Laboratory Co., Ltd.) can be mentioned.

Any silica precursor may be used as long as it forms silica by a reaction such as polycondensation in a raw material liquid. Examples of such a silica precursor include inorganic compounds such as sodium silicate and hydrolyzable groups having silicon atoms. And silane compounds bonded to silane, such as alkoxysilane and chlorosilane. Among these, tetraalkoxysilanes are preferable, and examples of such substances include tetramethoxysilane and tetraethoxysilane. These include ease of handling and safety, and stability and reactivity. This is preferable in terms of points, and more preferable.

The concentration of the inorganic oxide precursor in the coating solution is preferably 0.01 to 3.0 mol / L, more preferably 0.05 to 3.0 mol / L, and 0.05 to 2.0 mol / L. Is more preferable, and 0.05 to 1.0 mol / L is particularly preferable.

Examples of the solvent contained in the coating solution include water, alcohol (methanol, ethanol, propanol, etc.), polyvinyl alcohol (PVA) aqueous solution, ethylene glycol, and the like.

The coating liquid preferably further contains a chelating agent.
Examples of the chelating agent include monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), ethylenediaminetetraacetic acid (EDTA), citric acid, and the like.
The content of the chelating agent is preferably 0.5 to 5 equivalents, more preferably 1 to 2 equivalents, relative to the number of moles of the metal element contained in the coating solution.

The coating solution may contain various additives (such as various acids and various bases).
The content (total) of the additives is preferably 0.001 to 20% by mass and more preferably 0.01 to 10% by mass with respect to the total amount of the coating solution.

The coating method for the coating solution is not particularly limited, and known coating methods such as spin coating, dip coating, and spray coating can be used.

In the coating film forming step, drying (preliminary heat treatment) may be performed after coating.
The drying temperature is preferably 50 to 200 ° C, more preferably 100 to 140 ° C.
The drying time varies depending on the temperature, but is preferably 1 minute to 60 minutes, more preferably 1 minute to 20 minutes.
The drying can be performed on a known hot plate or dryer.

<Heat treatment process>
The heat treatment step is a step of heat-treating the coating film formed in the coating step at a temperature of 300 ° C. or higher.
The upper limit of the heat treatment temperature is not particularly limited, and may be any temperature that is lower than the lower one of the softening point of the support and the softening point of the hafnia film.
The temperature of the heat treatment is preferably from 300 ° C. to 1200 ° C., preferably from 300 ° C. to 900 ° C., and more preferably from 400 ° C. to 600 ° C. from the viewpoint of firing the precursor.
The heat treatment time varies depending on the temperature, but is preferably 0.5 to 3 hours, more preferably 0.5 to 1 hour.
In addition, preferable conditions for the heat treatment are the same as the conditions described in the section <Pretreatment> in << Inorganic structure >>.

<Steam treatment process>
The steam treatment step is a step of reducing the water droplet falling angle on the surface of the heat-treated coating film by steam-treating the heat-treated coating film.
In the steam treatment step, the water droplet falling angle on the surface of the inorganic structure material is preferably reduced by 10 ° or more, more preferably by 20 ° C. or more, and particularly preferably by 30 ° or more.
Preferable conditions for the steam treatment are the same as those described in the section <Steam treatment> and <Preferred conditions for steam treatment> in <Inorganic structure>.

<Other processes>
The manufacturing method of the inorganic thin film of this invention may have another process as needed.
Examples of other processes include the pretreatment process described above and the posttreatment process described above.

≪Inorganic thin film manufacturing method using vacuum film formation process≫
As another form of the method for producing an inorganic thin film of the present invention, a film forming step for forming an inorganic thin film on a support by a vacuum film forming method, and a heat treatment for heat-treating the formed inorganic thin film at a temperature of 300 ° C. or more A manufacturing method (hereinafter also referred to as “a manufacturing method of an inorganic thin film using a vacuum film-forming method”) having a process and a steam treatment process in which a heat-treated inorganic thin film is steam-treated in a steam atmosphere is also suitable.
According to the “method for producing an inorganic thin film using a vacuum film-forming method”, an inorganic thin film having a surface excellent in water droplet removal property and excellent in durability can be produced.
Further, according to the “method for manufacturing an inorganic thin film using a vacuum film forming method”, the density of the resistance points on the surface of the manufactured inorganic structure can be easily adjusted to 10 pieces / 30 mm ² or less.
Further, according to the “method for producing an inorganic thin film using a vacuum film formation method”, at least one of the region where the frictional force is 10 nN or less and the region where the dynamic friction coefficient is 1.0 or less is provided on the surface. It is easy to manufacture the inorganic thin film containing.
The “method for producing an inorganic thin film using a vacuum film-forming method” may include other steps as necessary.
Specifically, the “method for producing an inorganic thin film using a vacuum film-forming method” is suitable as a method for producing a hafnia film.

As the vacuum film forming method, a known method such as sputtering, CVD (Chemical Vapor Deposition), ion plating, vacuum deposition or the like can be used, but from the viewpoint of obtaining the effect of the present invention more effectively It is preferable that
Note that the sputtering power is not particularly limited as long as a desired surface roughness (Ra) and an appropriate film formation rate can be achieved.
The support is not particularly limited as long as it is a material that can withstand the heat treatment temperature as a post-treatment, and for example, the same support as described in the section “Structure” can be used. The support may be used as it is, or a support having a silica (SiO ₂ ) film or the like formed on the surface.

Preferable conditions for the heat treatment step are the same as those described in the section <Pretreatment> in << Inorganic structure >>.
The upper limit of the film formation temperature is not particularly limited, and may be any temperature lower than the lower one of the softening point of the support and the softening point of the inorganic thin film (for example, hafnia film) to be formed.
The temperature of the heat treatment is preferably 300 ° C. or higher and 1200 ° C. or lower from the viewpoint of crystallization.

The water vapor treatment step is a step of reducing the water droplet falling angle on the surface of the heat-treated inorganic thin film by subjecting the heat-treated coating film to water vapor treatment.
In the steam treatment step, the water droplet falling angle on the surface of the inorganic structure material is preferably reduced by 10 ° or more, more preferably by 20 ° C. or more, and particularly preferably by 30 ° or more.
Preferable conditions for the steam treatment are the same as those described in the section <Steam treatment> and <Preferred conditions for steam treatment> in <Inorganic structure>.

The manufacturing method of the inorganic thin film using the said vacuum film-forming method may have another process as needed.
Examples of other processes include the pretreatment process described above and the posttreatment process described above.

≪Glass article manufacturing method≫
The method for producing a glass article of the present invention includes a heat treatment step of heat treating a glass material at a temperature of 100 ° C. or more and 500 ° C. or less, and a heat treated glass material at a temperature of 30 ° C. or more and 100 ° C. or less and an absolute humidity of 15 g / m. A water vapor treatment step of carrying out water vapor treatment in ^three or more water vapor atmospheres.
The glass material here refers to a glass article before being subjected to heat treatment and water vapor treatment (that is, water slicking treatment), and is apparently manufactured glass article (glass article subjected to heat treatment and water vapor treatment). ). The glass material preferably has a high surface flatness (for example, a surface roughness Ra of 2 nm or less). For this purpose, a glass material having a mirror-polished surface or a float method is used. It is preferable to use a glass material.
Specific examples of the glass article are as described in the section of <Inorganic solid> in the << Inorganic structure >>.

According to the method for producing a glass article of the present invention, it is possible to produce a glass article having a surface excellent in water droplet removal property and further excellent in durability.
Moreover, according to the manufacturing method of the said glass article of this invention, it is easy to adjust the density of the said resistance point in the glass article surface manufactured to 10 pieces / 30mm < ² > or less.
In addition, according to the method for producing a glass article of the present invention, a glass article including at least one of a region where the frictional force is 10 nN or less and a region where the dynamic friction coefficient is 1.0 or less is produced on the surface. easy.

Preferable conditions for the heat treatment step are the same as those described in the section <Pretreatment> in << Inorganic structure >>.
The steam treatment step is a step of reducing a water droplet falling angle on the surface of the heat-treated glass material by steam-treating the heat-treated glass material.
In the steam treatment step, the water droplet falling angle on the surface of the inorganic structure material is preferably reduced by 10 ° or more, more preferably by 20 ° C. or more, and particularly preferably by 30 ° or more.
Preferable conditions for the steam treatment are the same as those described in the section <Steam treatment> and <Preferred conditions for steam treatment> in <Inorganic structure>.

≪Recovery method for water slidability of inorganic structures≫
In the method for recovering the water slidability of the inorganic structure of the present invention, the surface of the inorganic structure having a reduced water slidability (for example, the falling angle exceeds 50 °) is applied to a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / This is a method of recovering the water slidability of the inorganic structure (for example, setting the falling angle to 40 ° or less) by performing steam treatment in a steam atmosphere of m ³ or more.
According to this method, the water slidability of the surface of the inorganic structure once lost its slidability due to intense wear or the like can be recovered.
Preferable conditions for the steam treatment in the method for recovering water slidability of the inorganic structure are the same as those described in the section <Steam treatment> and <Preferred conditions for steam treatment> in <Inorganic structure>.
Further, the condition of the steam treatment in the above method may be a condition in which steam of about 50 to 100 ° C. is sprayed from a nozzle or the like.
The preferable conditions for spraying water vapor are also the same as the conditions described in the section <Water vapor treatment> in << Inorganic structure >>.

As described above, the inorganic structure, the structure, the manufacturing method of the inorganic structure, the manufacturing method of the inorganic thin film, the manufacturing method of the glass article, and the method of recovering the water slidability of the inorganic structure are: Since it is excellent in durability, it can be applied to various industrial fields such as vehicle-related, housing-related, optical equipment-related, industrial equipment-related, medical-related, electronic component-related, and electrical product-related.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.
“Room temperature” represents 25 ° C.
In the following, “contact angle” and “fall angle” refer to the water contact angle and the water drop fall angle, respectively, unless otherwise specified.

≪Preparation of various coating solutions≫
Various coating liquids (also referred to as “precursor solutions”) were prepared as coating liquids as follows.
<Alumina coating solution>
The alumina coating solution (0.1M) was prepared by dissolving aluminum nitrate nonahydrate in a solution of 0.1% by mass by dissolving polyvinyl alcohol (PVA, polymerization degree 500) in water. Prepared as a solution of L in aluminum nitrate nonahydrate.
In addition, the alumina coating solution (0.5M) was prepared by adding aluminum nitrate nonahydrate to a solution of monoethanolamine dissolved in methanol to make 0.5 mol / L, and using an ultrasonic cleaner (Bransonic 2510J-DTH). Yamato) and stirred for 1 hour to prepare a 0.5 mol / L aluminum nitrate nonahydrate solution.

<Hafnia coating solution>
The hafnia coating liquid (0.5M) is a solution in which ethanol, nitric acid (60% by mass) and water are mixed at a volume ratio of 9: 1: 0.2 (= ethanol: nitric acid (60% by mass): water). After hafnium chloride was dissolved, it was heated at 40 ° C. for 3 hours to prepare a 0.5 mol / L hafnium chloride solution.
Further, the hafnia coating liquid (0.1M) was prepared by adding methanol, nitric acid (60% by mass), and 0.1% by mass of an aqueous polyvinyl alcohol (PVA, polymerization degree 500) volume ratio 9: 1: 0. After dissolving hafnium chloride in a solution mixed with 2 (= methanol: nitric acid (60% by mass): 0.1% by mass aqueous solution of PVA), it was heated at 40 ° C. for 3 hours to obtain 0.1 mol / L Prepared as hafnium chloride solution.
The hafnia coating solution (0.01 M) was prepared as a 0.01 mol / L hafnium chloride solution in the same manner as the hafnia coating solution (0.1 M) except that the content of hafnium chloride was changed.

<Zirconia coating solution>
The zirconia coating solution was prepared by adding zirconium oxychloride octahydrate to a solution in which diethanolamine was dissolved in methanol to 0.5 mol / L, stirring for 1 hour using an ultrasonic cleaner, 0.5 mol / L Prepared as a zirconium oxychloride octahydrate solution.

<Ceria coating solution>
The ceria coat solution (0.1M) was prepared by dissolving cerium nitrate hexahydrate in a solution of polyvinyl alcohol (PVA, polymerization degree 500) dissolved in water to 0.05% by mass to obtain 0.1 mol / Prepared as a solution of L in cerium nitrate hexahydrate.
The ceria coat solution (0.01M) was prepared by dissolving cerium nitrate hexahydrate in a solution of 0.1% by mass of polyvinyl alcohol (PVA, polymerization degree 500) dissolved in water. Prepared as a 01 mol / L cerium nitrate hexahydrate solution.

<Titania coating solution>
As the titania coating solution, a photocatalytic titania coating solution NDH-510C manufactured by Nippon Soda Co., Ltd. was used.

<Titanium apatite (TiHAP) coating solution>
A titanium apatite (TiHAP) coating solution was prepared by the following procedure.
To a mixed solution of ethanol (50 mL) and 2-ethoxyethanol (50 mL), calcium nitrate tetrahydrate (4.246 g, 0.018 mol) was added and dissolved with stirring, and then phosphorous pentoxide (0.905 g, 0.006 mol) was added and stirred for 2 hours. Titanium tetraisopropoxide (0.568 g, 0.002 mol) was added to the resulting solution and stirred for half a day, followed by filtration. The resulting filtrate was used as a titanium apatite (TiHAP) coating solution.

[Experimental Example 1]
≪Formation and evaluation of simple metal oxide film≫
<Evaluation of zirconia (ZrO ₂ ) film>
The Pyrex (registered trademark) glass substrate was subjected to ultrasonic cleaning (60 ° C., 10 minutes) using a detergent. Next, the glass substrate was rinsed and dried, then heat-treated at 300 ° C. for 30 minutes, and cooled again to room temperature.
Next, 1 mL of the zirconia coating solution obtained above was applied on a glass substrate cooled to room temperature, and spin coating was performed at 1500 rpm for 10 seconds to form a coating film.
The glass substrate on which the coating film has been formed is allowed to stand for 10 minutes in a dryer adjusted to an atmospheric temperature of 120 ° C., and further, using a muffle furnace (KDF-P90G, Denken Co., Ltd.), in an air atmosphere, an atmospheric temperature of 500 ° C. For 0.5 hour, and further cooled in the muffle furnace for 5 hours to form a zirconia film on the glass substrate. The film surface temperature of the zirconia film after cooling for 5 hours was room temperature.

The zirconia film after cooling for 5 hours was subjected to steam treatment for 1 hour in an atmosphere of a temperature of 40 ° C. and a relative humidity of 90% (absolute humidity 46 g / m ³ ).
A constant temperature and humidity chamber (HUMIDIC CHAMBER IG420, Yamato Scientific Co., Ltd.) was used as the steam treatment apparatus.

Since the zirconia film produced as described above was colorless and transparent with no interference color, it was considered to be uniform and have a film thickness of several tens to several hundreds of nanometers.
Further, the surface roughness (Ra) of the zirconia film produced as described above was 9.8 nm.
In this experimental example, the surface roughness (Ra) was measured according to JIS B0601 (1994) using an AFM (atomic force microscope; VN-8000, manufactured by Keyence Corporation) under a measurement range of 50 μm square. Performed in compliance. The measurement method of the surface roughness (Ra) in the following experimental examples is the same as the measurement method in this experimental example, unless otherwise specified.

-Measurement of water contact angle and water drop falling angle-
The zirconia membrane before steaming is stored for 31 days in an indoor environment (temperature: 25 ° C., relative humidity: 60% (absolute humidity: 14 g / m ³ )), water contact angle (hereinafter also simply referred to as “contact angle”) and water droplet falling The change with time of the angle (hereinafter, also simply referred to as “falling angle”) was measured. Hereinafter, the obtained series of measured values is referred to as “no steam treatment (in the case)”.
In addition, the measuring method of a water contact angle and a water drop fall angle is as above-mentioned.
Regarding the falling angle, when the film surface does not fall even if the film surface is tilted to 90 ° with respect to the horizontal plane, it is indicated as “falling angle 90 °” for convenience.
Next, the steam treatment time was variously changed up to 31 days, and the contact angle and the falling angle for each treatment time were measured. Hereinafter, the obtained series of measured values is referred to as “with water vapor treatment (in the case)”.
The obtained results are shown in FIGS. 7A and 7B.

FIG. 7A is a graph showing a change in water contact angle in a zirconia membrane.
The “elapsed days” on the horizontal axis is the storage time (unit: day) in the indoor environment when there is no steam treatment, and the steam treatment time (unit: day) when there is steam treatment (hereinafter “day”). The same applies to the graph).
In FIG. 7A, the upstream side (the opposite side to the arrowhead side) of the white arrow is a plot group without steam treatment, and the downstream side (arrowhead side) of the white arrow is a plot group with steam treatment. Yes (same for subsequent graphs).
As shown in FIG. 7A, the contact angle was unstable when the steam treatment was not performed. Specifically, it was less than 20 ° within an elapsed time of 1 day, then gradually increased, and reached about 70 ° after an elapsed time of 31 days.
On the other hand, it was confirmed that when the steam treatment is performed, the contact angle is significantly increased, and in particular, the contact angle is increased to 90 ° or more by the treatment for 3 days or more.

FIG. 7B is a graph showing changes in the sliding angle in the zirconia film.
As shown in FIG. 7B, the falling angle was unstable when the steam treatment was not performed. Specifically, it was in the vicinity of 70 ° to 90 °.
On the other hand, it was confirmed that the falling angle is lowered when the steam treatment is performed. In particular, it was found that by performing the steam treatment for 7 days or more, the falling angle becomes 40 ° or less.

-XRD measurement-
About the zirconia film | membrane after a water vapor process, the XRD measurement (X-ray diffraction measurement) was performed using the X-ray-diffraction apparatus (RINT2100, Rigaku Corporation make).
Specifically, XRD measurement was performed using a parallel beam method with a tube voltage of 40 kV, a tube current of 30 mA, a scan step of 0.02 °, a scan speed of 2 ° / min, using copper as the counter cathode and nickel as the filter. .
FIG. 8 is an XRD measurement result of the zirconia film after the water vapor treatment.
As shown in FIG. 8, clear diffraction points were confirmed in the zirconia film, and the order indicating the crystal structure was confirmed.

<Evaluation of Alumina (Al ₂ O ₃ ) Film>
In the evaluation of the zirconia film, an alumina film was prepared and evaluated in the same manner as the evaluation of the zirconia film except that the zirconia coating liquid was changed to an alumina coating liquid (0.5 M).
Since the produced alumina film was colorless and transparent with no interference color, it was considered to be uniform and have a film thickness of several tens to several hundreds of nanometers.
Moreover, the surface roughness (Ra) of the alumina film produced as described above was 1.4 nm.

FIG. 9A is a graph showing a change in water contact angle in an alumina film.
As shown in FIG. 9A, the contact angle was unstable when the steam treatment was not performed. Specifically, the elapsed time was less than 40 ° within one day, and it tended to increase gradually from 50 ° to about 80 ° after three days elapsed.
On the other hand, it was confirmed that the contact angle is significantly increased by using the steam treatment, and in particular, the contact angle is increased to 80 ° or more by the treatment for 1 day or more.

FIG. 9B is a graph showing a change in the water drop falling angle in the alumina film.
As shown in FIG. 9B, in the case of no steam treatment, the falling angle was unstable. Specifically, the range was 40 ° to 90 °.
On the other hand, it was confirmed that the falling angle is lowered by the steam treatment. In particular, it has been found that the falling angle is 45 ° or less by performing the steam treatment for 7 days or more.

FIG. 10 is an XRD measurement result of the alumina film after the steam treatment.
As shown in FIG. 10, a clear diffraction point was not confirmed in the alumina film, and it was confirmed that the alumina film was amorphous.

<Evaluation of Ceria (CeO ₂ ) Film>
In the evaluation of the zirconia film, the ceria film (0.1M) and the zirconia coating liquid were changed in the same manner as the evaluation of the zirconia film except that the zirconia coating liquid was changed to the ceria coating liquid (0.1M) or (0.01M). Each ceria film (0.01M) was produced and evaluated.
The prepared ceria film (0.1M) and ceria film (0.01M) were both colorless and transparent because no interference color was seen, so that the film thickness was uniform and the film thickness was several tens to several hundreds nm. Seem.
Moreover, the surface roughness Ra of the produced ceria film (0.1M) was 2.0 nm.

FIG. 11A is a graph showing a change in the water contact angle in the ceria film without the water vapor treatment, and FIG. 11B is a graph showing a change in the water contact angle in the ceria film with the water vapor treatment.
As shown in FIG. 11A, the contact angle was unstable when no steam treatment was performed. Specifically, in the ceria film (0.1M), the contact angle that was less than 18 ° was increased to about 50 ° after storage for 15 days. In the ceria film (0.01M), the contact angle, which was about 16 °, increased to about 30 ° after storage for 15 days.
On the other hand, as shown in FIG. 11B, it was confirmed that the contact angle was significantly increased by the presence of the steam treatment. Specifically, it was confirmed that the contact angle rose to 80 ° or more for the ceria film (0.1M) and 70 ° or more for the ceria film (0.01M) by the treatment for 3 days or more.

FIG. 12A is a graph showing a change in the water drop falling angle in the ceria film without the water vapor treatment, and FIG. 12B is a graph showing a change in the water drop falling angle in the ceria film with the water vapor treatment.
As shown in FIG. 12A, in the ceria film (0.1M) and the ceria film (0.01M), the falling angle is always 90 ° or more from the beginning of the film formation until 30 days have elapsed, and the water droplet removability is extremely poor. It was.
On the other hand, as shown in FIG. 12B, it was confirmed that the falling angle is lowered by the presence of the steam treatment. Specifically, it was found that the treatment angle for 7 days or more lowered the sliding angle to 50 ° or less for the ceria film (0.1M) and to 40 ° or less for the ceria film (0.01M).

FIG. 13 is an XRD measurement result of the ceria film (0.1 M) after the water vapor treatment.
As shown in FIG. 13, clear diffraction points were confirmed in the ceria film, and the order indicating the crystal structure was confirmed.

<Evaluation of titania (TiO ₂ ) film>
In the evaluation of the zirconia film, the titania film was prepared and evaluated in the same manner as the evaluation of the zirconia film except that the zirconia coating liquid was changed to a titania coating liquid.
When the thickness of the produced titania film was measured using a spectroscopic ellipsometry or a scanning electron microscope (SEM), it was about 100 nm.

FIG. 14A is a graph showing a change in water contact angle in a titania film.
As shown in FIG. 14A, the contact angle was unstable when no steam treatment was performed. Specifically, the contact angle tended to be about 10 ° within an elapsed time of 1 day, and then gradually increased to reach about 25 ° after an elapsed time of 31 days.
On the other hand, it was confirmed that the contact angle is significantly increased by using the steam treatment, and in particular, the contact angle is increased to about 60 ° or more by the treatment for 7 days or more.

FIG. 14B is a graph showing the change of the water drop falling angle in the titania film.
As shown in FIG. 14B, the tumbling angle was always 90 ° or more from the beginning of the film formation until 30 days had elapsed, and the water droplet removal property was extremely poor.
On the other hand, it was confirmed that the falling angle is lowered by the steam treatment. In particular, it was confirmed that the falling angle becomes 60 ° or less by performing the steam treatment for 7 days or more.

<Evaluation of Hafnia (HfO ₂ ) Film>
In the evaluation of the zirconia film, hafnia was performed in the same manner as the evaluation of the zirconia film except that the zirconia coating liquid was changed to a hafnia coating liquid (0.5 M), (0.1 M), or (0.01 M). A film (0.5M), a hafnia film (0.1M), and a hafnia film (0.01M) were produced and evaluated.
The produced hafnia film (0.5M), hafnia film (0.1M), and hafnia film (0.01M) were colorless and transparent with no interference color. It seems to be several hundred nm.
Moreover, the surface roughness (Ra) of the produced hafnia film (0.1 M) was 6.9 nm.

FIG. 15A is a graph showing a change in the water contact angle in the hafnia film without the water vapor treatment, and FIG. 15B is a graph showing a change in the water contact angle in the hafnia film with the water vapor treatment.
As shown in FIG. 15A, the contact angle was unstable when no steam treatment was performed. For example, in a hafnia film (0.1 M), the contact angle, which was less than 10 °, rose to about 60 ° after storage for 15 days.
On the other hand, as shown in FIG. 15B, it was confirmed that the contact angle was significantly increased by the presence of the steam treatment. Specifically, it was confirmed that the contact angle rose to 80 ° or more by treatment for 1 day or more.

FIG. 16A is a graph showing a change in the water drop falling angle in the hafnia film without the water vapor treatment, and FIG. 16B is a graph showing a change in the water drop falling angle in the hafnia film with the water vapor treatment.
As shown in FIG. 16A, in the hafnia film (0.1M) and the hafnia film (0.01M), the tumbling angle is always 90 ° or more from the beginning of the film formation until the lapse of 7 days, and the water droplet removability is extremely poor. It was. After the 15th day, the falling angle had decreased to 50-70 °.
On the other hand, as shown in FIG. 16B, it was confirmed that the falling angle is reduced by the presence of the steam treatment. Specifically, it has been found that the rolling angle decreases to 50 ° or less for the hafnia film (0.1M) and 45 ° or less for the hafnia film (0.01M) by the treatment for one day or longer.

FIG. 17A is an XRD measurement result of a hafnia film (0.5M).
FIG. 17B is an XRD measurement result of the hafnia film (0.01M).
As shown in FIG. 17A, a clear diffraction point was confirmed in the hafnia film (0.5M), and an order indicating a crystal structure was confirmed.
As shown in FIG. 17B, a clear diffraction point was not confirmed in the hafnia film (0.01M), and it was confirmed that the hafnia film (0.01M) was amorphous.

<Evaluation of blank (glass substrate)>
For the purpose of confirming the effect of the water vapor treatment on the silica (SiO ₂ ) film, the effect of the water vapor treatment on the blank (glass substrate) was confirmed.
The steam treatment was performed under the conditions of “temperature 40 ° C., relative humidity 90% (absolute humidity 46 g / m ³ )” and “temperature 40 ° C., relative humidity 20% (absolute humidity 10 g / m ³ )” (water vapor Other conditions for the treatment are the same as those for the zirconia film).
FIG. 18A is a graph showing a change in the water contact angle in the blank when there is a steam treatment, and FIG. 18B is a graph showing a change in the water drop falling angle in the blank when there is a steam treatment.
As shown in FIG. 18A, the contact angle increased as the processing time increased.
In particular, at a “temperature of 40 ° C. and a relative humidity of 90% (absolute humidity of 46 g / m ³ )”, the contact exceeded 55 ° after 3 days of treatment. The condition of the absolute humidity of 46 g / m ³ had a greater effect of increasing the contact angle than the condition of the absolute humidity of 10 g / m ³ .
As shown in FIG. 18B, at “temperature of 40 ° C. and relative humidity of 90%”, the falling angle was maintained at 30 ° or less. The condition of the absolute humidity of 46 g / m ³ had a greater effect of lowering the sliding angle than the condition of the absolute humidity of 10 g / m ³ .

[Experimental example 2]
≪Formation and evaluation of composite metal oxide film≫
<Evaluation of alumina-titania film>
(Evaluation of contact angle and sliding angle)
In the evaluation of the zirconia film of Experimental Example 1, the zirconia coating solution was changed to a mixed solution of alumina coating solution (0.5 M) and titania coating solution (volume of alumina coating solution: volume of titania coating solution = 100: 1). Except for the above, a film containing alumina and titania (alumina-titania film (100: 1)) was prepared in the same manner as the zirconia film described above, and the contact angle and the falling angle were measured.
Further, the volume ratio of the alumina coating liquid (0.5 M) and the titania coating liquid was changed (volume of the alumina coating liquid: volume of the titania coating liquid = 10: 1 or 1: 1) to obtain an alumina-titania film (100: 1) An alumina-titania film (10: 1) was prepared, and changes in contact angle and sliding angle with respect to the steam treatment time were measured.
The surface roughness Ra of the alumina-titania film (100: 1) was 1.4 nm.
The surface roughness Ra of the alumina-titania film (10: 1) was 1.5 nm.
The surface roughness Ra of the alumina-titania film (1: 1) was 1.6 nm.
Further, a simple alumina film was produced as a control by the same method as in Experimental Example 1, and changes in contact angle and falling angle with respect to the steam treatment time were measured.

The above measurement results are shown in FIGS. 19A and 19B.
In FIG. 19A and FIG. 19B, for example, “Al—Ti 100: 1 40 ° C. 90%” represents a mixed solution of alumina coating liquid (0.5 M): titania coating liquid volume = 100: 1. It shows that the alumina-titania film obtained by using this was a sample obtained by steam treatment under conditions of a temperature of 40 ° C. and a relative humidity of 90% (absolute humidity of 46 g / m ³ ).
“Al-MEA” indicates a simple film of alumina.
As shown in FIG. 19A, a high contact angle was exhibited in each condition, but in the case of a relative humidity of 90% (absolute humidity of 46 g / m ³ ), it exceeded 80 ° by treatment for 3 days or more. Was confirmed.
In addition, as shown in FIG. 19B, a decrease in the falling angle was confirmed when the ratio of the alumina coating liquid (0.5 M) was high and the relative humidity was 90% (absolute humidity 46 g / m ³ ). It was.

(Evaluation of photocatalytic activity)
Next, for the alumina-titania film “Al—Ti 100: 1 40 ° C. 90%”, an experiment on the vapor phase decomposition of isopropyl alcohol (IPA) gas by light irradiation was performed to evaluate the photocatalytic activity.
First, the alumina-titania film obtained above was allowed to stand in a sealed container replaced with synthetic air, IPA gas (isopropyl alcohol gas) was injected to a concentration of 2000 ppm, and stored in a dark place for 23 hours. Thereafter, the alumina-titania film was irradiated with ultraviolet rays (UV).
Here, black light (FL10BL-B, manufactured by National) was used as the ultraviolet rays. In addition, the intensity of the ultraviolet light applied to the alumina-titania film was set to 1 mW / cm ² by adjusting the distance between the light and the substrate.
The gas in the sealed container was sampled every UV irradiation time, and the concentration of the remaining IPA gas (raw material) and the concentration of acetone (product) were measured by gas chromatography.

Further, the same experiment was performed for the alumina-titania film “Al—Ti 10: 1, 40 ° C. 90%” and the alumina-titania film “Al—Ti 1: 1, 40 ° C. 90%”.

FIG. 20 shows the evaluation result of photocatalytic activity for “Al—Ti 100: 1 40 ° C. 90%”, and FIG. 21 shows the evaluation result of photocatalytic activity for “Al—Ti 10: 1 40 ° C. 90%”. The evaluation results of the photocatalytic activity for “Al—Ti 1: 1 40 ° C. 90%” are shown in FIG.
20, 21, and 22, the horizontal axis (BL irradiation time / h) represents the black light irradiation time (unit: hours), and the left vertical axis (IPA / ppm) represents the remaining IPA gas. It is an axis | shaft showing a density | concentration (unit: ppm), and the vertical axis | shaft (Acetone / ppm) on the right side is an axis | shaft showing the density | concentration (unit: ppm) of acetone which is a product.
As shown in FIGS. 20, 21, and 22, “Al—Ti 100: 1 40 ° C. 90%”, “Al—Ti 10: 1 40 ° C. 90%”, and “Al—Ti 1: 1 40 ° C.” The photocatalytic activity was confirmed in any of “90%”.

<Evaluation of zirconia-titania film>
(Evaluation of contact angle and sliding angle)
In the evaluation of the zirconia film of Experimental Example 1, the zirconia coating liquid was changed to a mixed solution of zirconia coating liquid and titania coating liquid (volume of zirconia coating liquid: volume of titania coating liquid = 100: 1). A film containing zirconia and titania (zirconia-titania film) was produced in the same manner as for the zirconia film 1 and the contact angle and the falling angle were measured.
Furthermore, the volume ratio of the zirconia coating liquid and the titania coating liquid was variously changed (volume of the zirconia coating liquid: volume of the titania coating liquid = 10: 1 or 1: 1), and changes in the contact angle and the falling angle with respect to the steam treatment time. Was measured.
The surface roughness Ra of the zirconia-titania film (100: 1) was 1.5 nm.
The surface roughness Ra of the zirconia-titania film (10: 1) was 1.1 nm.
The surface roughness Ra of the zirconia-titania film (1: 1) was 1.5 nm.
In addition, a simple zirconia film was prepared as a control, and changes in the contact angle and the falling angle with respect to the steam treatment time were measured.

The above measurement results are shown in FIGS. 23A and 23B.
In FIG. 23A and FIG. 23B, for example, the notation such as “Zr—Ti 100: 1 40 ° C. 90%” was obtained using a mixed solution of zirconia coating solution volume: titania coating solution volume = 100: 1. This shows that the sample was obtained by subjecting a zirconia-titania film to steam treatment under conditions of a temperature of 40 ° C. and a relative humidity of 90% (absolute humidity of 46 g / m ³ ).
“Zr-DEA” represents a simple film of zirconia.
As shown in FIG. 23A, a high contact angle was exhibited in each condition, and in particular, it was confirmed that it exceeded 80 ° in the treatment for 8 days or more.
In addition, as shown in FIG. 23B, a drop in the falling angle was confirmed particularly in the case of a relative humidity of 90% (absolute humidity of 46 g / m ³ ).

<Evaluation of hafnia-titania film>
(Evaluation of contact angle and sliding angle)
In the evaluation of the zirconia film of Experimental Example 1, the zirconia coating liquid was changed to a mixed solution of hafnia coating liquid and titania coating liquid (volume of hafnia coating liquid: volume of titania coating liquid = 100: 1). A film containing hafnia and titania (hafnia-titania film) was prepared in the same manner as the zirconia film 1 and the contact angle and the falling angle were measured.
Further, the volume ratio between the hafnia coating liquid and the titania coating liquid was changed variously (the volume of the hafnia coating liquid: the volume of the titania coating liquid = 10: 1 or 1: 1), and the change of the contact angle and the falling angle with respect to the steam treatment time. Was measured.
In addition, a simple hafnia film was prepared as a control by the same method as in Experimental Example 1, and changes in contact angle and sliding angle with respect to the steam treatment time were measured.

The above measurement results are shown in FIGS. 24A and 24B.
In FIG. 24A and FIG. 24B, for example, the notation “Hf—Ti 100: 1 40 ° C. 90%” or the like was obtained by using a mixed solution of hafnia coat liquid volume: titania coat liquid volume = 100: 1. This shows that the sample was obtained by subjecting a hafnia-titania film to steam treatment under conditions of a temperature of 40 ° C. and a relative humidity of 90% (absolute humidity of 46 g / m ³ ).
Further, "Hf 40 ° C. 90%" indicates that the Tan'ajimaku hafnia, temperature 40 ° C., a sample obtained by steam treatment at a relative humidity of 90% (absolute humidity 46 g / ^{m 3)} ing.
As shown in FIG. 24A, a high contact angle was exhibited in each condition, but a high contact angle was exhibited particularly when the ratio of hafnia was high.
Further, as shown in FIG. 24B, a drop in the falling angle was confirmed particularly in the case of a relative humidity of 90% (absolute humidity of 46 g / m ³ ).

<Evaluation of titanium apatite film (TiHAP)>
(Evaluation of contact angle and sliding angle)
In the evaluation of the zirconia film of Experimental Example 1, a titanium apatite film (TiHAP) was prepared in the same manner as the zirconia film of Experimental Example 1 except that the zirconia coating liquid was changed to a titanium apatite (TiHAP) coating liquid. The falling angle was measured.

The measurement results are shown in FIGS. 25A and 25B.
In FIG. 25A and FIG. 25B, the plot of “TiHAP_1” is a plot when the steam treatment is performed at the indicated temperature and relative humidity when the plot is “40 ° C. and 95%” when stored in a room temperature environment.
As shown in FIG. 25A, the contact angle was remarkably increased by the treatments of “90 ° C. 25%” and “90 ° C. 50%”.
Further, as shown in FIG. 25B, the rolling angle was remarkably reduced by the treatment of “90 ° C. 50%”.

[Experimental Example 3]
≪Evaluation of resistance point density and water repellency≫
For various inorganic thin films (Sample 1 to Sample 27) including the simple metal oxide film and the composite metal oxide film produced above, the resistance point density and water repellency (contact angle and falling angle) The correlation of was evaluated.
The method of measuring the resistance point density, contact angle, and sliding angle is as described above.
The evaluation results are shown in Table 2.
The preparation conditions for each sample are as follows.

(Sample 1)
The alumina film prepared in Example 1 (alumina film after cooling for 5 hours at the muffle furnace), the temperature 40 ° C., in an atmosphere of 95% relative humidity (absolute humidity 48 g / m ^3), and stored for 2 months (In other words, steam treatment was performed).
(Sample 2)
The alumina film prepared in Experimental Example 1 (the alumina film after being cooled in the muffle furnace for 5 hours) was immersed in pure water at 70 ° C. for 1 hour and subjected to hot water treatment.
The alumina film after the hot water treatment was stored for 2 months in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity of 48 g / m ³ ) (that is, subjected to steam treatment).
(Sample 3)
It is the alumina film (alumina film after cooling for 5 hours in the muffle furnace) produced in Experimental Example 1 (resistance point density and water repellency were evaluated without storage).
(Sample 4)
The alumina film prepared in Experimental Example 1 (the alumina film after being cooled in the muffle furnace for 5 hours) was immersed in pure water at 70 ° C. for 1 hour and subjected to hot water treatment.
The alumina membrane after the hot water treatment was stored for 1 day in the same indoor environment as in Experimental Example 1.
(Sample 5)
The alumina film produced in Experimental Example 1 (the alumina film after cooling in the muffle furnace for 5 hours) was stored for 4 days in the same indoor environment as in Experimental Example 1.

(Sample 6 to Sample 10)
Each of the Al film, Au film, Cr film, Si film, and Ti film formed under the following conditions was stored for 2 months in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity of 48 g / m ³ ). (In other words, steam treatment was performed).
As a substrate for forming each film, the same glass substrate as in Experimental Example 1 was used.

-Al film deposition conditions-
The cleaned glass substrate was set in a resistance heating vacuum deposition apparatus (EBH-6). An aluminum wire (diameter: 1 mm, 99.999%, manufactured by Sigma-Aldrich) was set in the W port (distance between the deposition port and the substrate was 15 cm), and evacuated to 2 × 10 ⁻⁶ Torr with a rotary pump and a diffusion pump. Thereafter, the heating current was gradually increased to perform preheating and degassing, and then vapor deposition was performed at a film forming rate of 2 nm / sec for 3 minutes (film thickness 371 nm). Substrate heating is not performed in vapor deposition. After vapor deposition, it was naturally cooled and then taken out.

-Au film formation conditions-
The cleaned glass substrate was set in a resistance heating vacuum deposition apparatus (EBH-6). First, Cr was deposited as a base film by about 5 nm by the method described later. After that, a gold wire (diameter 0.5 mm, 99.99%, manufactured by Sigma-Aldrich) was set in the W port (distance between the deposition port and the substrate was 15 cm), and 2 × 10 ⁻⁶ Torr with a rotary pump and a diffusion pump. After vacuum evacuation, the heating current was gradually increased to preheat and degas, and then vapor deposition was performed at a film forming rate of 0.5 nm / sec for 200 seconds (film thickness of about 100 nm). Substrate heating is not performed in vapor deposition. After vapor deposition, it was naturally cooled and then taken out.

-Cr film formation conditions-
The cleaned glass substrate was set in a resistance heating vacuum deposition apparatus (EBH-6). A chromium chip (99.995%, manufactured by Sigma-Aldrich) was set in the Ta port, and the distance between the vapor deposition port and the substrate was 15 cm. After evacuating to 2 × 10 ⁻⁶ Torr with a rotary pump and a diffusion pump, the heating current was gradually increased to preheat and degas, and then deposition was performed at a film forming rate of 0.6 nm / sec for 170 seconds ( (Film thickness of about 100 nm). Substrate heating is not performed in vapor deposition. After vapor deposition, it was naturally cooled and then taken out.

-Si film and Ti film sputtering conditions-
On a cleaned soda lime glass substrate (substrate size 50 mm × 50 mm × 2 mmt), a Si thin film and a Ti thin film were formed by sputtering under the following conditions.

(1) Si sputtering conditions-Equipment: Personal coater (specification change machine manufactured by Nisshin Seiki Co., Ltd.)
・ Power source: REACTIVE PLASMA GENERATOR (PRG-50 manufactured by ENI Technology, Inc.), input power: 250 W (pulse)
・ Target: Si (4N, 40 mm × 200 mm × 5 mmt, 0,01Ω · cm or less, made by Mitsui Metals)
・ Substrate heating: None ・ Back pressure: 2.0 × 10 ⁻⁴ Pa
Total pressure during sputtering: Ar (100%) was introduced at a gas flow rate of 30 sccm, and the main valve was adjusted to a total pressure of 0.3 Pa.
Under the above sputtering conditions, after 10 minutes of pre-sputtering, the substrate transport speed was 8.3 cm / min and passed under two reciprocating targets, and the film thickness was 114 nm and Ra = 0.4 nm (25 μm ² ).

(2) Ti sputtering conditions-Equipment: Personal coater (specification change machine manufactured by Nisshin Seiki Co., Ltd.)
・ Power supply: DC power supply, input power: 1.2KW
-Target: Ti (4N, 40mm x 200mm x 5mmt, made by Sumitomo Metal)
・ Substrate heating: None ・ Back pressure: 2.0 × 10 ⁻⁴ Pa
Total pressure during sputtering: Ar (100%) was introduced at a gas flow rate of 30 sccm, and the main valve was adjusted to a total pressure of 0.3 Pa.
Under the above sputtering conditions, after 10 minutes of pre-sputtering, the substrate transport speed was 10.0 cm / min, and passed under two reciprocating targets, and the film thickness was 100 nm and Ra = 8.3 nm (25 μm ² ).

(Sample 11 to Sample 12)
Each of the quartz glass and the silicon wafer was stored for 2 months in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity of 48 g / m ³ ) (that is, subjected to steam treatment).

(Sample 13 to Sample 14)
Using a zirconia coating solution prepared under the following conditions, a zirconia film (zirconia film after cooling in the muffle furnace for 5 hours) prepared in the same manner as in Experimental Example 1 was measured in the same indoor environment as in Experimental Example 1. Stored for months.

-Preparation of zirconia coating solution for sample 13-
A zirconia coating solution (2% by mass) is obtained by dissolving zirconium oxyacetate in a solution of 0.1% by mass of polyvinyl alcohol (PVA, polymerization degree 500) dissolved in water. Prepared as a solution.

-Preparation of zirconia coating solution for sample 14-
A zirconia coating solution (2 mass%) is obtained by dissolving zirconium oxyacetate in a solution obtained by mixing 1-propanol (1-PrOH) and water in a volume ratio of 28: 7 (= 1-propanol: water). Prepared as a weight percent zirconium oxyacetate solution.

(Sample 15 to Sample 17)
The zirconia-titania film prepared in Experimental Example 2 (zirconia-titania film after cooling in the muffle furnace for 5 hours) was stored for 5 months in the same indoor environment as in Experimental Example 1.

(Sample 18 to Sample 20)
The treatment shown in Table 2 was performed for the period shown in Table 2 on the titania film prepared in Experimental Example 1 (the titania film after being cooled in the muffle furnace for 5 hours).

(Sample 21 to Sample 24)
A titania film was formed on the glass substrate used in Experimental Example 1 by sputtering under the following conditions. The manufactured substrate with a titania film was subjected to heat treatment (firing) at an atmospheric temperature of 500 ° C. for the time shown in the “treatment” column of Table 2 using a muffle furnace (KDF-P90G, manufactured by Denken Co., Ltd.).
The substrate with the titania film after firing was stored for the period shown in Table 2 in the same indoor environment as in Experimental Example 1.

-Titania (TiO ₂ ) sputtering conditions-
-Equipment: Personal coater (specification change machine manufactured by Nisshin Seiki Co., Ltd.)
・ Power supply: MAGNETRON DRIVE (manufactured by Advanced Energy), input power: DC1200W
・ Target: Ti
・ Substrate heating: None ・ Back pressure: 2.0 × 10 ⁻⁴ Pa,
Total pressure during sputtering: Oxygen was introduced at a gas flow rate of 6 sccm and Ar was introduced at a gas flow rate of 24 sccm, and the main valve was adjusted to a total pressure of 0.3 Pa. At this time, the oxygen partial pressure is 20%.
Under the above sputtering conditions, a TiO ₂ thin film was formed to a thickness of 100 nm after pre-sputtering.

(Sample 25 to Sample 27)
Samples 22 to 24 were prepared in the same manner as Samples 22 to 24 except that a silica film (underlying film) was formed on a glass substrate and a titania film was formed on the formed silica film. Samples 25 to 27 were prepared.
Here, the silica film (underlying film) was formed by sputtering under the following conditions.

-Silica (SiO ₂ ) sputtering conditions-
-Equipment: Personal coater (specification change machine manufactured by Nisshin Seiki Co., Ltd.)
・ Power source: REACTIVE PLASMA GENERATOR (PRG-50 manufactured by ENI Technology, Inc.), input power: 250 W (pulse)
・ Target: Si
・ Substrate heating: None ・ Back pressure: 2.0 × 10 ⁻⁴ Pa
Total pressure during sputtering: Oxygen (100%) was introduced at a gas flow rate of 30 sccm, and the main valve was adjusted to a total pressure of 0.5 Pa.
Under the above sputtering conditions, a SiO ₂ thin film having a thickness of 20 nm was formed after pre-sputtering.

<Description of Table 2>
In the remarks column, “water droplets remain stretched” indicates a state in which when the water droplets drip, the water droplets extend in the direction of dripping and a part of the water droplets remain on the thin film.
The average value “999” of the resistance points indicates that the resistance points are very many and are 999 points / 30 mm ² or more, which is the measurement limit of this condition.

As shown in Table 2, in the samples (1, 8 to 10, 12 to 14, 16, 18, 22, 23, 25 to 27) having a resistance point density of 10/30 mm ² or less, the resistance point density is Compared with the sample exceeding 10 pieces / 30 mm ² , the contact angle was high and the sliding angle was low.
In addition, it was confirmed that it is effective to perform the steam treatment in order to set the density of the resistance points to 10 pieces / 30 mm ² or less.

[Experimental Example 4]
≪Study on steam treatment conditions≫
<Evaluation of alumina film>
In the evaluation of the alumina film of Experimental Example 1, the conditions of the water vapor treatment and the treatment time were variously changed, and the change in the water contact angle was measured.
The measurement results are shown in FIG.
Details of each steam treatment condition in FIG. 26 are as follows.

(Steam treatment conditions)
"Temperature 40 ° C, relative humidity 95%"
A treatment in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity of 48 g / m ³ ) is shown.
"Temperature 60 ° C, relative humidity 38%"
... Temperature 60 ° C., illustrates a process in an atmosphere of a relative humidity of 38% (absolute humidity 49g / ^{m 3).}
“Temperature 80 ° C, relative humidity 17%”
A treatment in an atmosphere of a temperature of 80 ° C. and a relative humidity of 17% (absolute humidity of 50 g / m ³ ) is shown.
"Temperature 20 ° C, relative humidity 95%"
A treatment in an atmosphere of a temperature of 20 ° C. and a relative humidity of 95% (absolute humidity of 16 g / m ³ ) is shown.
“Temperature 80 ° C, relative humidity 95%”
A treatment in an atmosphere of a temperature of 80 ° C. and a relative humidity of 95% (absolute humidity of 277 g / m ³ ) is shown.
"Temperature 80 ℃, dry"
... temperature 80 ° C, treatment in a dry atmosphere in a dryer (ANS-111S, natural convection thermostat, Isuzu Seisakusho).
"Indoor environment"
This is the result when stored in an atmosphere of a temperature of 25 ° C. and a relative humidity of 60% (absolute humidity 14 g / m ³ ). Under this condition, the number of processing days represents storage time.
"Temperature 80 ° C, relative humidity 50%"
A treatment in an atmosphere at a temperature of 80 ° C. and a relative humidity of 50% (absolute humidity 146 g / m ³ ) is shown.
"Temperature 80 ° C, relative humidity 30%"
A treatment in an atmosphere of a temperature of 80 ° C. and a relative humidity of 30% (absolute humidity of 88 g / m ³ ) is shown.
"Temperature 80 ° C (autoclave)"
The treatment in an atmosphere at a temperature of 80 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
In addition, in this specification, all the processes described as “autoclave” mean a process using saturated steam, that is, a process using a steam atmosphere having a relative humidity of 100%.
"Temperature 100 ° C (autoclave)"
A treatment in an atmosphere at a temperature of 100 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
"Temperature 120 ° C (autoclave)"
The treatment in an atmosphere at a temperature of 120 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
"Temperature 150 ° C (autoclave)"
A treatment in an atmosphere at a temperature of 150 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
“Temperature 180 ° C (autoclave)”
The treatment in an atmosphere at a temperature of 180 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
“Temperature 90 ° C, relative humidity 30%”
A treatment in an atmosphere of a temperature of 90 ° C. and a relative humidity of 30% (absolute humidity of 126 g / m ³ ) is shown.
"Temperature 90 ° C, relative humidity 50%"
A treatment in an atmosphere of a temperature of 90 ° C. and a relative humidity of 50% (absolute humidity of 211 g / m ³ ) is shown.
"Temperature 95 ° C, relative humidity 25%"
... Temperature 95 ° C., illustrates a process in an atmosphere of 25% relative humidity (absolute humidity 126g / ^{m 3).}

As shown in FIG. 26, there are differences in the contact angle arrival level and temporal changes depending on the conditions of the steam treatment, and there are optimum treatment conditions for increasing the contact angle. For example, the contact angle does not reach 90 ° under the condition where the absolute humidity value is lower than 15 g / m ³ . In addition, when the absolute humidity is too high, as in autoclave treatment at multiple temperature points (treatment with saturated steam), the contact angle increases once and then decreases or contacts at the first day of treatment. A time change below the initial value of the corner occurs.

<Evaluation of hafnia film>
In the evaluation of the hafnia film in Experimental Example 1, the conditions of the water vapor treatment and the treatment time were variously changed, and the change in the water contact angle was measured.
The measurement results are shown in FIG.
The details of each steam treatment condition in FIG. 27 are as follows.

(Steam treatment conditions)
"Temperature 40 ° C, relative humidity 95%"
A treatment in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity of 48 g / m ³ ) is shown.
"Temperature 90 ° C, relative humidity 50%"
A treatment in an atmosphere of a temperature of 90 ° C. and a relative humidity of 50% (absolute humidity of 211 g / m ³ ) is shown.
"Temperature 150 ° C (autoclave)"
A treatment in an atmosphere at a temperature of 150 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
"Temperature 120 ° C (autoclave)"
The treatment in an atmosphere at a temperature of 120 ° C. after sealing and sealing with 5 cc of pure water in a container with an internal volume of 300 cc at room temperature and normal pressure is shown.
"Temperature 95 ° C, relative humidity 25%"
A treatment in an atmosphere having a temperature of 95 ° C. and a relative humidity of 25% (absolute humidity 126 g / m ³ ) is shown.

As shown in FIG. 27, there are differences in the level of contact angle and the change with time depending on the conditions of the steam treatment, and there are optimum treatment conditions for increasing the contact angle. For example, when the absolute humidity value is too high, such as autoclave treatment at 120 ° C. and 150 ° C. (saturated steam treatment), the contact angle once increases and then decreases.

[Experimental Example 5]
≪Evaluation of durability (friction resistance) ≫
The hafnia film (0.1 M, steam treatment condition 40 ° C., 46 g / m ³ , treatment time 15 days) produced in Experimental Example 1 was subjected to a traverse test under the following conditions to determine the durability (friction resistance) of the film. evaluated.

(Traverse test conditions)
Load: 0.1 kg / cm ² (JIS L 3102-1978 cotton canvas 1206)
Speed: 30 round trips / minute

(Test results)
With respect to the hafnia film, the contact angle and the sliding angle were not significantly changed before and after the 500 reciprocating tests, and the sliding property was maintained.

[Experimental Example 6]
≪Contrast experiment between inorganic thin film and organic thin film≫
<Observation of internal flow of water drops>
Using the alumina membrane (0.1 M, steam treatment condition 40 ° C., 46 g / m ³ , treatment days 30 days) produced in Experimental Example 1, the internal flow of the falling water droplets was observed.
Specifically, using a contact angle measuring device (Drop Master 500, Kyowa Interface Chemical Co., Ltd.) and a falling angle measuring device (SA-11, Kyowa Interface Chemical Co., Ltd.), after dropping 30 mg of water droplets on the surface of the thin film, While tilting the surface of the thin film with respect to a horizontal plane using a falling angle measuring device, water droplets were observed from a camera attached to the contact angle measuring device.

Next, as a control, an organic thin film was formed on a silicon wafer substrate under the following conditions, and the same observation was performed on the organic thin film.
-Organic thin film formation conditions-
1H, 1H, 2H, 2H-heptadecafluorodecyltrimethoxysilane (FAS-17, CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , TSL8233, GE Toshiba Silicone) is converted to 1,3-bis (trifluoromethyl) benzene ( It was dissolved in C ₆ H ₄ (CF ₃ ) ₂ ) to obtain a 130 μM solution. The cleaned silicon wafer was immersed in this solution for 1 day, then washed with acetone, methylene chloride, acetone and water in that order, and dried in a dryer at 80 ° C.

As a result of observation, the internal flow of the water droplets falling on the surface of the alumina film showed a different behavior from the internal behavior of the water droplets falling on the surface of the organic thin film.
Specifically, the internal flow of water droplets falling on the surface of the organic thin film slides down in a rotation mode in which the entire droplet rotates in a caterpillar shape, whereas the internal flow of water droplets falling on the surface of the alumina film is Although the front part of the droplet was in a caterpillar rotation mode, the rear part had a complicated internal flow different from the simple rotation mode.

[Experimental Example 7]
≪Steam treatment experiment for silicon≫
As a result of performing water vapor treatment (treatment conditions: 40 ° C., 46 g / m ³ ) on the mirror-polished surface of the silicon wafer and measuring the change in water contact angle while changing the treatment time, the water contact angle was 28 °. It rose to 94 ° (after 112 days) from (initial value). That is, an increase in contact angle due to the water vapor treatment was also confirmed for silicon.

[Experimental Example 8]
≪Effect of steam treatment after indoor environment storage≫
For alumina, titania and hafnia obtained in Experimental Example 1, after thin film preparation (after cooling in the muffle furnace for 5 hours), for alumina, 28 days for titania, 145 days for titania, 19 days for hafnia, each indoor environment and stored at (temperature 25 ° C., absolute humidity of 14 g / ^{m 3} (relative humidity 61%)).
Thereafter, the treatment time was changed under steam treatment conditions of 40 ° C. and 46 g / m ³ , and the change in water contact angle was measured. The measurement results are shown in FIGS. 28A and 28B.
FIG. 28A is a graph showing a change in water contact angle with respect to the steam treatment time, and FIG. 28B is a graph showing a change in water drop falling angle with respect to the steam treatment time.
As shown in FIG. 28A and FIG. 28B, even if the film is stored for a certain period in the indoor environment after the thin film is produced, the water contact angle rises to the same level as in Experimental Example 1 and reaches the same level as in Experimental Example 1 by steam treatment. It was confirmed that the drop angle of water drops was lower.

[Experimental Example 9]
≪Material that does not lubricate by steam treatment≫
The organic film was subjected to water vapor treatment (treatment conditions: 40 ° C., 46 g / m ³ ), the treatment time was changed, and the water contact angle change was measured.
The organic films used in the experiment are polypropylene and polyethylene terephthalate, polyvinyl chloride, polyoxymethylene, polycarbonate, ABS, nylon, polyethylene, polystyrene, and acrylic resin. Among them, for polyvinyl chloride, nylon, and acrylic resin, the water contact angle increased by 10 ° or more by the steam treatment. For other organic films, even when the water contact angle decreased or increased, it was kept below 10 °. Table 3 shows the treatment time and changes in the water contact angle.

<Description of Table 3>
“PP”: Organic film, polypropylene.
“PET”: Organic film, polyethylene terephthalate.
“PVC”: Organic film, polyvinyl chloride.
“POM”: Organic film, polyoxymethylene.
“PC”: Organic film and polycarbonate.
“ABS”: Organic film, ABS (acrylonitrile-butadiene-styrene copolymer).
“PA”: Organic membrane, nylon.
“PE”: Organic film, polyethylene.
“PS”: Organic film, polystyrene.
“MA”: Organic film and acrylic resin.

[Experimental Example 10]
≪Conditions that do not lubricate with steam treatment≫
Immediately after producing the alumina film of Experimental Example 1 (immediately after cooling in the muffle furnace for 5 hours), it was immersed in pure water at 70 ° C. for 1 hour and subjected to hydrothermal treatment.
The water contact angle immediately after the hot water treatment was 46 °. Thereafter, steam treatment (treatment conditions: 40 ° C., 46 g / m ³ ) was carried out for 3 days, but the water contact angle did not rise to the level of experimental example 1 (about 90 °), and the reached contact angle reached 74 °. Stayed.
As described above, if the hot water treatment is performed on the alumina membrane before the steam treatment, the water sliding effect by the steam treatment is weakened.
Similarly, in a thin film stored in general air for a long time after film formation, the surface is contaminated with organic matter and covered with adsorbed molecules, thereby reducing the effect of water slidability by subsequent water vapor treatment.
Therefore, it is desirable to perform steam treatment as soon as possible after production.

[Experimental Example 11]
≪Dependence on droplet composition≫
Using an alumina membrane (0.1 M, water vapor treatment conditions 40 ° C., 46 g / m ³ , treatment days 30 days) and an organic thin film (FAS-17 and ODS), the composition of the water droplets can be variously changed to achieve a droplet composition. Dependency was examined. The measuring method is the same as the measuring method of the falling angle except that the water droplet is changed from pure water to various solutions.
In the case of an alumina membrane surface, the falling angle of a 5% by mass sucrose aqueous solution is 46 °, the falling angle of a 25% by mass diethylene glycol methyl ether aqueous solution is 8 °, the falling angle of a 25% by mass isopropyl alcohol aqueous solution is 10 °, and a NaCl solution (10 The falling angle of (mass% aqueous solution) was 30 °.
That is, in the case of the alumina film, good water slidability was exhibited in any of the above compositions, but it was confirmed that the composition of the droplet composition depended on the drop angle depending on the droplet composition.
On the other hand, in the case of the organic thin film, the drop composition dependency of the falling angle was not confirmed.
As described above, it was confirmed that there are various differences in the falling behavior between the inorganic thin film and the organic thin film.

[Experimental Example 12]
≪Resliding smoothness≫
Loaded to 0.1 kg / cm ² (JIS L 3102-1978 cotton canvas 1206) on the surface of an alumina thin film (0.1 M) subjected to water slicking treatment (treatment conditions: 40 ° C., 46 g / m ³ , 140 days) Speed: 30 The contact angle deteriorated from 93 ° to 80 ° and the sliding angle deteriorated from 21 ° to 67 ° when the traverse test was carried out 20 times in the reciprocation / minute condition. The slipperiness was recovered by performing 40 ° C. and 46 g / m ³ for 3 days, and the contact angle was restored to 93 ° and the falling angle was 33 °.

[Experimental Example 13]
≪Water vapor treatment experiment on glass substrate≫
First, a soda-lime glass (SLG) substrate is subjected to heat treatment at any one of 150 ° C., 300 ° C., 400 ° C., 500 ° C., 600 ° C., and 700 ° C. for 1 hour, followed by steam treatment (temperature 90 ° C., The relative humidity was 50% (absolute humidity 211 g / m ² )), and the changes in the water contact angle and the water droplet falling angle with respect to the steam treatment time were measured.
In Experimental Example 13, as the soda lime glass (SLG) substrate, the surface of Asahi Glass float glass (JIS R3202) on the atmosphere open side was used.
The heat treatment was performed in an air atmosphere using a muffle furnace (KDF-P90G, manufactured by Denken Co., Ltd.).
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

FIG. 29 is a graph showing a change in water contact angle (°) with respect to the steam treatment time (elapsed time (days) in a steam atmosphere).
As shown in FIG. 29, when the temperature of the heat treatment was 150 ° C., 300 ° C., 400 ° C., and 500 ° C., the effect of improving the water contact angle by the steam treatment was remarkably obtained.

FIG. 30 is a graph showing a change in the water drop falling angle (°) with respect to the steam treatment time (elapsed time (days) in a steam atmosphere).
As shown in FIG. 30, when the temperature of the heat treatment is 150 ° C., 300 ° C., 400 ° C., and 500 ° C., the effect of lowering the water drop falling angle by the steam treatment was remarkably obtained.

-Comparative experiment example-
The steam of the glass substrate was changed except that the steam treatment was stored in a dry atmosphere (Superdrybox manufactured by TOYO Living adjusted to a temperature of 25 ° C. and a relative humidity of 2% (absolute humidity 0.5 g / m ² )). In the same manner as in the treatment experiment, changes in the water contact angle and the water drop falling angle with respect to the storage time were measured.
FIG. 31 is a graph showing a change in water contact angle (°) with respect to storage time (elapsed time (days) in a dry atmosphere).
As shown in FIG. 31, even when heat treatment at any temperature was performed, the water contact angle was about 50 ° or less.
FIG. 32 is a graph showing changes in the water drop falling angle (°) with respect to storage time (elapsed time (days) in a dry atmosphere).
As shown in FIG. 32, the water drop falling angle did not decrease or was unstable.

-Heat treatment temperature and surface roughness Ra-
Table 4 below shows the surface roughness Ra (nm) of the glass at 28 ° C. and the surface roughness Ra (nm) of the glass after the heat treatment at each temperature.
The surface roughness Ra (nm) was measured by the same method as in Experimental Example 1 except that the measurement range was 0.5 μm square.

As shown in Table 4, no direct correlation was found between the effect of the steam treatment and the heat treatment temperature.
The reason why the effect of improving the contact angle and reducing the falling angle is weak when the heat treatment temperature is 600 ° C. and 700 ° C. is not clear, but is related to the fact that it is close to the softening point (730 ° C.) of soda lime glass. Guessed.

-Durability (rub resistance test) test-
In the above, a traverse test under the same conditions as in Experimental Example 5 was performed on the sample subjected to the heat treatment at 300 ° C. and the steam treatment (90 ° C., 50%).
FIG. 33 is a graph showing the relationship between the number of sliding times, the contact angle, and the falling angle.
As shown in FIG. 33, the contact angle was maintained at about 70 ° or more until the number of sliding times of 500, and the sliding angle was maintained at 40 ° or less until the number of sliding times of 500. Thus, the surface excellent in static water repellency and dynamic water repellency obtained by heat treatment and steam treatment was also excellent in durability (friction resistance).

[Experiment 14]
≪Water vapor treatment experiment on metal substrate≫
<Water vapor treatment experiment for Ag polishing plate>
First, the Ag polishing plate was heat treated at 500 ° C. for 1 hour, followed by water vapor treatment (temperature 40 ° C., relative humidity 95% (absolute humidity 48 g / m ² )), water contact angle and water droplet falling with respect to the water vapor treatment time. The change in angle was measured.
Note that Ag (manufactured by Niraco Co., Ltd., product number AG-403322, size 0.1 mm × 100 mm × 100 mm, purity 99.98%) was used as the Ag polishing plate.
The heat treatment was performed in an air atmosphere using a muffle furnace (KDF-P90G, manufactured by Denken Co., Ltd.).
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

On the other hand, changes in the water contact angle and the water droplet falling angle with respect to the steam treatment time were measured in the same manner as described above except that the heat treatment was not performed.

FIG. 34 is a graph showing a change in water contact angle (°) with respect to a water vapor treatment time (elapsed time (days)) in an Ag polishing plate.
As shown in FIG. 34, when heat treatment was performed (“with heat treatment”), the water contact angle temporarily decreased after the heat treatment (see the time point of elapsed time 0 days), but by performing steam treatment The water contact angle recovered to 80 ° or more.

FIG. 35 is a graph showing the change of the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Ag polishing plate.
As shown in FIG. 35, when the heat treatment was performed (“with heat treatment”), the water droplet falling angle temporarily increased after the heat treatment (see the time point of the elapsed time of 0 days), but the steam treatment should be performed. As a result, the water droplet contact angle decreased to about 50 °.

<Water vapor treatment experiment for Cu polishing plate>
Except for changing the Ag polishing plate to a Cu polishing plate, changes in the water contact angle and the water drop falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
As the Cu polishing plate, Nilaco Cu (product number CU-113321, size 0.1 mm × 100 mm × 100 mm, purity 99.96%) was used.

FIG. 36 is a graph showing a change in water contact angle (°) with respect to a water vapor treatment time (elapsed time (days)) in a Cu polishing plate.
As shown in FIG. 36, when the heat treatment was performed (“with heat treatment”), the water contact angle temporarily decreased after the heat treatment (see the time point of the elapsed time of 0 days). The water contact angle recovered to 80 ° or more.

FIG. 37 is a graph showing the change of the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Cu polishing plate.
As shown in FIG. 37, when the heat treatment was performed (“with heat treatment”), the water droplets did not fall.

<Water vapor treatment experiment for Al polishing plate>
Except that the Ag polishing plate was changed to an Al polishing plate, changes in the water contact angle and the water drop falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
As the Al polishing plate, Nilaco's Al (part number AL-013321, size 0.1 mm × 100 mm × 100 mm, purity 99.999%) was used.

FIG. 38 is a graph showing a change in water contact angle (°) with respect to a water vapor treatment time (elapsed time (days)) in an Al polishing plate.
As shown in FIG. 38, when the heat treatment was performed (“with heat treatment”), the water contact angle temporarily decreased after the heat treatment (see the time point of the elapsed time 0 days), but by performing the steam treatment The water contact angle recovered to 80 ° or more.

FIG. 39 is a graph showing the change of the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Al polishing plate.
As shown in FIG. 39, when the heat treatment was performed (“with heat treatment”), the water droplet falling angle temporarily increased after the heat treatment (see the time point of the elapsed time of 0 days), but the water vapor treatment should be performed. As a result, the water droplet contact angle decreased to about 40 ° or less.

<Water vapor treatment experiment on Ni polishing plate>
Except that the Ag polishing plate was changed to a Ni polishing plate, changes in the water contact angle and the water droplet falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
As the Ni polishing plate, Nilaco Ni (product number NI-313324, size 0.1 mm × 100 mm × 500 mm, purity 99 +%) was used.

FIG. 40 is a graph showing a change in water contact angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Ni polishing plate.
As shown in FIG. 40, when the heat treatment was performed (“with heat treatment”), the water contact angle temporarily decreased after the heat treatment (see the time point of elapsed time 0 days), but by performing the steam treatment The water contact angle recovered to 80 ° or more.

FIG. 41 is a graph showing a change in the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Ni polishing plate.
As shown in FIG. 41, when the heat treatment was not performed (“no heat treatment”), the water droplet falling angle could be reduced to 50 ° or less by the steam treatment, but when the heat treatment was performed (“with heat treatment”). ) Did not fall.

<Water vapor treatment experiment for Fe polishing plate>
Except for changing the Ag polishing plate to an Fe polishing plate, the changes in the water contact angle and the water drop falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
As the Fe polishing plate, Nilaco Co., Ltd. (product number FE-223329, size 0.1 mm × 150 mm × 150 mm, purity 99.50%) was used.

FIG. 42 is a graph showing a change in water contact angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Fe polishing plate.
As shown in FIG. 42, when the heat treatment was performed (“with heat treatment”), the water contact angle did not increase even when the steam treatment was performed.

FIG. 43 is a graph showing a change in the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Fe polishing plate.
As shown in FIG. 43, when the heat treatment was not performed (“no heat treatment”), the water droplet falling angle could be reduced to 50 ° or less by the steam treatment, but when the heat treatment was performed (“with heat treatment”). ) Did not fall.

<Water vapor treatment experiment for Ti polishing plate>
Except that the Ag polishing plate was changed to a Ti polishing plate, changes in the water contact angle and the water drop falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
As the Ti polishing plate, Nilaco Ti (product number TI-453321, size 0.1 mm × 100 mm × 100 mm, purity 99.50%) was used.

FIG. 44 is a graph showing a change in water contact angle (°) with respect to a water vapor treatment time (elapsed time (days)) in a Ti polishing plate.
As shown in FIG. 44, when the heat treatment was performed (“with heat treatment”), the water contact angle temporarily decreased after the heat treatment (see the time point of the elapsed time 0 days). The water contact angle recovered to 70 ° or more.

FIG. 45 is a graph showing the change of the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Ti polishing plate.
As shown in FIG. 45, in both cases of heat treatment (“with heat treatment”) and no heat treatment (“no heat treatment”), the water droplet falling angle is reduced to 50 ° or less by steam treatment. I was able to.

<Water vapor treatment experiment for Si wafer>
Except that the Ag polishing plate was changed to a Si wafer, changes in the water contact angle and the water drop falling angle with respect to the water vapor treatment time were measured in the same manner as in the <Water vapor treatment experiment on the Ag polishing plate>.
Si wafers manufactured by Aki Corporation (diameter 100mm ± 0.5mm, N-type, plane orientation (100), thickness 525 ± 25μm, resistance 1-10Ω · cm, orientation flat 32.5 ± 2.5mm, Single-sided mirror polishing) was used.

FIG. 46 is a graph showing a change in water contact angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Si wafer.
As shown in FIG. 46, the water contact angle is increased to 80 ° or more by steam treatment in both cases where heat treatment was performed (“with heat treatment”) and when heat treatment was not performed (“no heat treatment”). I was able to.

FIG. 47 is a graph showing a change in the water drop falling angle (°) with respect to the water vapor treatment time (elapsed time (days)) in the Si wafer.
As shown in FIG. 47, when the heat treatment was performed (“with heat treatment”), the water droplet falling angle temporarily increased after the heat treatment (see the time point of the elapsed time of 0 days), but the steam treatment should be performed. As a result, the water droplet contact angle decreased to 20 ° or less.

<Summary of steam treatment experiment on metal substrate>
The results of the water vapor treatment experiment on the metal substrate in Experimental Example 14 are summarized as shown in Table 5 below.

In Table 5, in the column of “water drop tumbling property”, the case where the water drop tumbling angle is less than 90 ° is defined as “falling”, and the case where the metal plate does not fall even when tilted at 90 ° with respect to the horizontal plane is indicated as “x”. Indicated.
As shown in Table 5, when the heat treatment was not performed, the surface roughness Ra was small in any metal substrate, and water droplet falling property was confirmed after the water vapor treatment.
When the heat treatment is performed, the Ag polishing plate, the Al polishing plate, the Ti polishing plate, and the Si wafer have a small surface roughness Ra even when the heat treatment is performed, as in the case of the glass substrate (Experimental Example 13), Dropping of water droplets was confirmed after the steam treatment.

In addition, in the case of Ag polishing plate, Al polishing plate, Ti polishing plate, and Si wafer, when the heat treatment is performed (“with heat treatment”), the water contact angle temporarily decreases after the heat treatment (at the time when the elapsed time is 0 days), A common tendency was observed that the water contact angle was recovered by performing steam treatment (FIGS. 34, 38, 44, and 46).
In addition, in these metal substrates, when heat treatment is performed (“with heat treatment”), the water droplet falling angle temporarily increases after the heat treatment (see the time point of elapsed time 0), and the water droplet contact angle is obtained by performing the water vapor treatment. There was a common trend of lowering (FIGS. 35, 39, 45, and 47).
The behavior of the water contact angle and water drop falling angle in these metal substrates is such that the surface organic substances are once removed by heat treatment to become a hydrophilic state, and then the surface of the H ₂ O having a special structure is formed by steam treatment. It is presumed that the cluster and the organic matter are stacked with good uniformity in a state where the resistance point is small (see, for example, FIG. 56), and as a result, the water droplet contact angle is reduced.

On the other hand, with respect to the Cu polishing plate, the Ni polishing plate, and the Fe polishing plate, the water droplets did not fall down when the heat treatment was performed. The reason for this is not clear, but it is presumed that this is because the surface roughness Ra is increased by the heat treatment.

[Experimental Example 15]
≪Formation and evaluation of hafnia film≫
<Preparation of Hafnia Film (1000 ° C.) Sample>
Using a magnetron sputtering apparatus, the sputtering target is Hf, and after evacuating to a sufficient ultimate vacuum, the oxygen partial pressure is 100%, the total pressure is 0.3 Pa, and the sputtering DC power is 300 W on the sapphire glass substrate (support). A hafnia film (asdepo) of about 100 nm was formed.

Note that the sputtering power is not limited to the above power as long as a desired surface roughness (Ra) and an appropriate deposition rate can be achieved. The support is not particularly limited as long as it is a material that can withstand the heat treatment temperature as a post-treatment. The support may be used as it is, or a support having a silica (SiO ₂ ) film or the like formed on the surface. In this experimental example, the film forming method by the sputtering method has been described, but a known method such as sputtering, CVD, ion plating, vacuum deposition, or the like can be used as the film forming method.

The hafnia film (asdepo) after film formation was subjected to heat treatment (annealing) at 1000 ° C. for 90 minutes.
The heat treatment was performed in an air atmosphere using a muffle furnace (KDF-P90G, manufactured by Denken Co., Ltd.).
A hafnia film (1000 ° C.) sample was thus manufactured.

<Preparation of Hafnia Film (500 ° C.) Sample>
The sapphire glass substrate was changed to a soda lime glass substrate having a silica film formed on the surface, and a hafnia film (asdepo) of about 100 nm was formed on the silica film (underlayer film) under the same conditions as described above. Here, the conditions for forming the silica film are the same as the conditions for forming the SiO ₂ film in Samples 25 to 27 of Experimental Example 3.
The deposited hafnia film (asdepo) was subjected to heat treatment (annealing) at 500 ° C. for 30 minutes.
The heat treatment was performed in an air atmosphere using a muffle furnace (KDF-P90G, manufactured by Denken Co., Ltd.).
As described above, a sample of a hafnia film (500 ° C.) was produced.
Hereinafter, the conditions not described in this experimental example are the same as the conditions in Experimental example 1.

<Results of XRD measurement>
FIG. 48 shows the XRD measurement result of the hafnia film (500 ° C.) and the hafnia film (asdepo) after the film formation and before the heat treatment, and FIG. 49 shows the heat treatment after the hafnia film (1000 ° C.) and the film formation. It is a XRD measurement result of the previous hafnia film | membrane (asdepo).
As shown in FIGS. 48 and 49, in both the hafnia film (500 ° C.) and the hafnia film (1000 ° C.), the diffraction lines indicating the crystal structure are increased after the heat treatment as compared with asdepo. It was confirmed that crystallization was progressing.
In particular, it was confirmed that the crystallization of the hafnia film (1000 ° C.) is more advanced than the hafnia film (500 ° C.).

<Steam treatment>
Next, each of the hafnia film (500 ° C.) and the hafnia film (1000 ° C.) is left in a water vapor atmosphere (that is, subjected to a water vapor treatment), and changes in water contact angle and water droplet falling angle with respect to the standing time (treatment time). Was measured. Further, as a comparison, the changes in the water contact angle and the water droplet falling angle with respect to the standing time when the hafnia film (500 ° C.) and the hafnia film (1000 ° C.) were left in a dry atmosphere (Dry) were measured.
The details of the steam treatment conditions and the dry atmosphere conditions are as follows.

-Steam treatment conditions and dry atmosphere conditions-
"40 ° C, 95%"
... left in an atmosphere of a temperature of 40 ° C. and a relative humidity of 95% (absolute humidity 48 g / m ³ ).
"90 ° C, 50%"
... left in an atmosphere of a temperature of 90 ° C. and a relative humidity of 50% (absolute humidity 211 g / m ³ ).
"Dry"
... left in a dry atmosphere (Superdrybox manufactured by TOYO LIVING, adjusted to a temperature of 25 ° C and a relative humidity of 2% (absolute humidity 0.5 g / m ² )).

FIG. 50 is a graph showing a change in water contact angle in a hafnia film (500 ° C.).
As shown in FIG. 50, when the water vapor treatment is performed (“40 ° C., 95%”, “90 ° C., 50%”), the time is shorter than when left in a dry atmosphere (Dry). It was possible to raise the contact angle. The effect of increasing the contact angle was particularly remarkable under the condition of “90 ° C., 50%”.

FIG. 51 is a graph showing changes in the water drop falling angle in a hafnia film (500 ° C.).
As shown in FIG. 51, when left in a dry atmosphere (Dry), the water droplets did not fall.
On the other hand, by performing steam treatment (“40 ° C., 95%”, “90 ° C., 50%”), the water droplet falling angle could be reduced. The effect of reducing the water drop falling angle is remarkable at “90 ° C., 50%”. Under these conditions, the water drop falling angle could be reduced by treatment for 24 hours.

FIG. 52 is a graph showing a change in water contact angle in a hafnia film (1000 ° C.).
As shown in FIG. 52, the effect of increasing the contact angle was particularly remarkable under the condition of “90 ° C., 50%”.

FIG. 53 is a graph showing changes in the water drop falling angle in the hafnia film (1000 ° C.).
As shown in FIG. 53, when left in a dry atmosphere (Dry), the water drop falling angle showed an unstable behavior.
On the other hand, when steam treatment (“40 ° C., 95%”, “90 ° C., 50%”) is performed, the water droplet falling angle can be reduced, and after the standing time of 24 hours, the water droplet falling angle is It was stable.

<Surface roughness Ra>
In order to investigate the correlation between the water drop falling angle and the surface roughness, a sample in which the hafnia film (1000 ° C.) was allowed to stand for 340 hours under the “Dry” condition (a sample with a high water drop falling angle) and a hafnia film (1000 ° C.) were set to “90”. The surface roughness Ra was measured for a sample that was left for 340 hours under the condition of “° C., 50%” (a sample having a low waterdrop angle).
The surface roughness Ra was measured under two conditions of a measurement range of 25 μm square and a measurement range of 0.5 μm square at each of three locations (measurement points 1 to 3) in each sample.

As shown in Table 6 above, all the samples had a small surface roughness Ra, and no significant difference was observed in the surface roughness Ra.
The reason why the water drop sliding angle decreased for the sample of “90 ° C., 50%” is presumed to be that the surface resistance point was reduced by the steam treatment in addition to the small surface roughness Ra.

[Experimental Example 16]
≪Measurement of friction force and dynamic friction coefficient before and after steam treatment≫
The surface of each measurement sample below was measured for friction force and dynamic friction coefficient.
The measurement of the frictional force and the dynamic friction coefficient was performed on each measurement sample before and after the steam treatment.
Here, the conditions for the steam treatment were such that the measurement sample was stored for 4 days (96 hours) in a steam atmosphere at a temperature of 90 ° C. and a relative humidity of 50%.
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

<Measurement sample>
Alumina film (Al ₂ O ₃ ): An alumina film similar to the alumina film (sol-gel method) produced in Experimental Example 1 was used.
Hafnia film (HfO ₂ ) A hafnia film similar to the hafnia film (0.1M) (sol-gel method) produced in Experimental Example 1 was used.
Quartz glass substrate (Quartz Glass; Q.G.) A quartz glass substrate having a surface roughness Ra of 0.3 nm ± 0.1 nm (within 25 μm square) on both sides was used.
-Stainless steel substrate (Stainless steel (SUS)) ... The surface roughness Ra of one side (surface subjected to water vapor treatment) produced by single-side mirror polishing of a SUS304 substrate (Niraco Co., Ltd., model No. 75323) is 1. A SUS304 substrate (hereinafter also referred to as “SUS304 mirror polishing plate”) having a thickness of 6 nm ± 0.1 nm (within 25 μm square) was used.

<Measurement method>
A friction force microscope (manufactured by JEOL Ltd., product name: JSPM-5200) was attached with the following cantilever, and the surface of the measurement sample was scanned with the probe of the cantilever to measure the friction force and the dynamic friction coefficient.

~ Cantilever ~
-Product name: Olympus OMCL-RC800PSA-1
-Spring constant in the vertical direction (thickness direction): 0.05 [N / m]
・ Material: Silicon nitride (Si ₃ N ₄ )
・ Lever width w: w = 20 [μm]
・ Lever thickness t: t = 0.8 [μm]
・ Lever length l: l = 200 [μm]
-Probe length h: h = 2.9 [μm]
Shear elastic modulus G: G = 7.35 × 10 ¹⁰ [N / m ² ]
-Torsion spring constant k: k = 0.000375 [N / rad]
* Here, the torsion spring constant k is a value obtained by the following equation (A).
k = (wt ³ G) / (3l (h + t / 2)) Formula (A)
[In Formula (A), w, t, G, l, and h represent a lever width, a lever thickness, a shear elastic modulus, a lever length, and a probe length, respectively. ]

-Measurement conditions-
・ Measurement mode: Contact mode ・ Pressing pressure N: N = 14 [nF]
-Clock (time required to measure one point): 333.33 μsec
Number of measurement points: 256 points × 256 points for each sample Measurement range (scanning area): 2 μm × 2 μm (alumina film) or 0.5 μm × 0.5 μm (hafnia film, QG, SUS)
Scanning speed: 5.9 [μm / sec] (alumina film) or 1.5 [μm / sec] (hafnia film, Q.G., SUS)
* Here, the scanning speed was calculated by dividing the scanning distance (2 μm or 1.5 μm) by the time (clock 333.33 μsec × 256 points) required to scan one line (256 points) at the measurement location.

~ Friction force F ~
Using the measurement voltage V measured under the above measurement conditions, the frictional force F was determined according to the following formula (B).
F = (ka (V−V ₀ ) / 2d) × 10 ⁹ [nN] Formula (B)
In the above formula (B), k, a, V, V ₀ , and d represent the following values, respectively.
-Torsion spring constant k: k = 0.000375 [N / rad]
Force sensitivity a (apparatus-dependent value): a = 0.015 [mm / V]
-Measurement voltage V: Voltage measured under the above measurement conditions -Reference voltage V ₀ : V ₀ = 0 [V]
-Distance d between optical detector and cantilever (device-dependent value): d = 40 [mm]

～ Dynamic friction coefficient μ ～
The dynamic friction coefficient μ was determined according to the following formula (C).
μ = F ^M / N Formula (C)
In the above formula (C), ^{F M} and N respectively represent the following values.
Friction force F ^M : Mode value F ^M of the friction force F in one measurement (256 points × 256 points)
・ Pressing pressure N: N = 14 [nF]

<Measurement result of frictional force F>
~ Friction force F ~
FIG. 57 is a graph showing the measurement results of the frictional force of the alumina film (Al ₂ O ₃ ).
FIG. 58 is a graph showing the measurement results of the frictional force of the hafnia film (HfO ₂ ).
59 is a graph showing the measurement results of the frictional force of the quartz glass substrate (QG).
FIG. 60 is a graph showing the measurement results of the frictional force of the stainless steel substrate (SUS).

57 to 60, the horizontal axis represents the friction force F (Friction Force (nN)), and the vertical axis represents the frequency.
57 to 60, “pre.” Represents the friction force before the steam treatment, and “tre.” Represents the friction force after the steam treatment.
In FIGS. 57 to 60, one waveform shows the result of one measurement (256 points × 256 points). For example, FIG. 57 shows the result of performing the frictional force measurement before the water vapor treatment twice and the frictional force measurement after the water vapor treatment three times for the alumina film. Therefore, FIG. 57 shows two “pre.” Waveforms and three “tre.” Waveforms.

As shown in FIG. 57, in the alumina film, the surface frictional force was reduced by the water vapor treatment. Specifically, the mode of friction force after the steam treatment (referred to as a peak value; the same applies hereinafter) was less than half of the mode of friction force before the steam treatment.
Further, the surface of the alumina film after the water vapor treatment included a region where the frictional force was 10 nN or less.
Further, the contact angle before the water vapor treatment, the contact angle after the water vapor treatment, the water droplet falling angle before the water vapor treatment, and the water droplet falling angle after the water vapor treatment were measured for this alumina film, respectively. 8 °, 83.0 ° ± 2.1 °, 90 °, and 14 ± 1 °.

As shown in FIG. 58, the surface frictional force of the hafnia film was reduced by the water vapor treatment. Specifically, the mode value of the frictional force after the steam treatment was less than half compared to the mode value of the frictional force before the steam treatment.
In addition, the surface of the hafnia film after the water vapor treatment included a region where the frictional force was 10 nN or less.
Further, with respect to the hafnia film, the contact angle before the steam treatment, the contact angle after the steam treatment, the water drop falling angle before the steam treatment, and the water drop falling angle after the steam treatment were measured. 0.5 °, 86.7 ° ± 0.3 °, 90 °, and 16.7 ° ± 1.2 °.

As shown in FIG. 59, in the quartz glass substrate, the surface frictional force was reduced by the water vapor treatment. Specifically, the mode value of the frictional force after the steam treatment was less than half compared to the mode value of the frictional force before the steam treatment.
Further, the surface of the quartz glass substrate after the water vapor treatment included a region where the frictional force was 10 nN or less.
Further, the quartz glass substrate was measured for a contact angle before the water vapor treatment, a contact angle after the water vapor treatment, a water droplet falling angle before the water vapor treatment, and a water droplet falling angle after the water vapor treatment. They were 1.1 °, 77.4 ° ± 1.1 °, 90 °, and 21 ° ± 1 °.

As shown in FIG. 60, in the stainless steel substrate, the surface frictional force was reduced by the steam treatment. Further, the surface of the stainless steel substrate after the steam treatment included a region where the frictional force was 10 nN or less.
Further, when the contact angle before the steam treatment, the contact angle after the steam treatment, the water drop falling angle before the steam treatment, and the water drop falling angle after the steam treatment were measured for this stainless steel substrate, 10.1 ° ± 1 7 °, 80.3 ° ± 0.9 °, 90 °, and 32 ° ± 1.4 °.

<Measurement results of dynamic friction coefficient μ>
The dynamic friction coefficient μ for each measurement sample is shown in Table 7 below.

As shown in Table 7, the dynamic friction coefficient μ of the surface was lowered by the steam treatment in any measurement sample. In particular, for the alumina film, the hafnia film, and the quartz glass substrate, the dynamic friction coefficient μ (average value) was lowered to 1.0 or less.

<Comparative example>
Next, as a comparative example, the friction force and the dynamic friction coefficient were measured in the same manner as described above for the following measurement sample that was not subjected to the steam treatment.
-Silicon wafer (Si (100)) ... Phosphorus-doped N-type Si (Aki Corporation)
・ Sapphire glass (Sapphire (0001)): Al ₂ O ₃ (Aki Corporation)

FIG. 61 is a graph showing the measurement results of the frictional force of a silicon wafer and sapphire glass that have not been subjected to water vapor treatment.
As shown in FIG. 61, the silicon wafer and the sapphire glass not subjected to the water vapor treatment both had high frictional force and did not include a region where the frictional force was 10 nN or less.

Further, the dynamic friction coefficient μ of the silicon wafer not subjected to the water vapor treatment is 1.6, and the dynamic friction coefficient μ of the sapphire glass not subjected to the water vapor treatment is 1.3, both of which exceed 1.0. It was.

[Experimental Example 17]
≪Study of steam treatment conditions 2≫
Excimer lamp irradiation treatment or ultrasonic cleaning treatment is performed as a pretreatment on the surface of each measurement sample below (pretreatment conditions are shown below), and then water vapor treatment under various conditions (water vapor treatment conditions are as follows) For 4 days, and the contact angle and water drop falling angle after the steam treatment were measured.
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

<Measurement sample>
Stainless steel substrate: The same SUS304 mirror polishing plate as the SUS304 mirror polishing plate used in Experimental Example 16 was used.
-Soda lime glass substrate The same soda lime glass substrate as the soda lime glass substrate used in Experimental Example 13 was used.
Quartz glass substrate: The same quartz glass substrate as that used in Experimental Example 16 was used.
Alumina film (Al ₂ O ₃ ): An alumina film similar to the alumina film used in Experimental Example 16 was used.
Hafnia film (HfO ₂ ) A hafnia film similar to the hafnia film used in Experimental Example 16 was used.

<Conditions for pretreatment>
Excimer lamp irradiation treatment: As a pretreatment, an excimer lamp (UEP20B manufactured by Ushio Electric Co., Ltd., wavelength 172 nm) is applied to the surface of each measurement sample on the side subjected to water vapor treatment at an intensity of 10 mW / cm ² . Irradiated for 166 hours.
-Ultrasonic cleaning treatment: For the surface of each measurement sample on the side subjected to the steam treatment, an ultrasonic cleaning device (5510J-MT 42 kHz, manufactured by BRANSON, USA) is used as a pretreatment, in a pure soft detergent 1: 4 pure aqueous solution. And ultrasonic cleaning treatment for 0.33 hours under the condition of 135 W.

<Steam treatment conditions>
-28 degreeC 2% RHdrybox ... In the dryer shown in Experimental Example 15, the measurement sample was stored for 4 days in the water vapor atmosphere of temperature 28 degreeC and relative humidity 2% conditions.
40 ° C. and 95% RH constant temperature bath: The measurement sample was stored for 4 days in a steam atmosphere at 40 ° C. and 95% similar to the conditions described in Experimental Example 4.
-90 degreeC 50% RH constant temperature bath ... The measurement sample was stored for 4 days in the 90 degreeC50% water vapor | steam atmosphere similar to the conditions demonstrated in Experimental example 4. FIG.
-120 degreeC auto-grave ... The measurement sample was stored for 4 days in the water vapor | steam atmosphere of the 120 degreeC auto-grave similar to the conditions demonstrated in Experimental example 4.
-180 degreeC auto-grave ... The measurement sample was stored for 4 days in the water vapor | steam atmosphere of the 180 degreeC auto-grave conditions similar to the conditions demonstrated in Experimental example 4. FIG.

<Evaluation results>
-Stainless steel substrate-
Table 8 shows pretreatment conditions, water vapor treatment conditions, contact angle after water vapor treatment, and water drop falling angle for the stainless steel substrate.
As shown in Table 8, the temperature x relative humidity is 3800 (° C.%), 4500 (° C.%), or 12000 (° C.%) (particularly, the temperature x relative humidity is 3800 (° C.% ) Or 4500 (degrees C.%) water vapor treated stainless steel showed excellent sliding properties (low sliding angle).
Among these conditions, a particularly preferable condition from the viewpoint of further suppressing the surface oxidation is a temperature × relative humidity of 3800 (° C.%) or 4500 (° C.%).

~ Soda lime glass substrate ~
Table 9 shows pretreatment conditions, water vapor treatment conditions, contact angle after water vapor treatment, and water drop falling angle for a soda lime glass substrate.
As shown in Table 9, the soda-lime glass substrate subjected to the steam treatment under the conditions of temperature × relative humidity of 3800 (° C./%) or 4500 (° C./%) has an excellent sliding property (low falling angle). Indicated.

-Quartz glass substrate-
Table 10 shows the pretreatment conditions, the steam treatment conditions, the contact angle after the steam treatment, and the water drop falling angle regarding the alumina film (Al ₂ O ₃ ).
As shown in Table 10, the quartz glass subjected to the steam treatment under the conditions of temperature × relative humidity of 3800 (° C./%) or 4500 (° C./%) showed excellent sliding property (low sliding angle). .

~ Alumina film ~
Table 11 shows the pretreatment conditions, the steam treatment conditions, the contact angle after the steam treatment, and the water drop falling angle for the alumina film.
As shown in Table 11, the alumina film subjected to the steam treatment under the conditions of temperature × relative humidity of 3800 (° C./%) or 4500 (° C./%) showed excellent sliding property (low sliding angle). .

~ Hafnia film ~
Table 12 shows pretreatment conditions, water vapor treatment conditions, contact angle after water vapor treatment, and water drop falling angle for the hafnia film.
As shown in Table 12, the hafnia film subjected to the steam treatment under the conditions of temperature × relative humidity of 3800 (° C./%) or 4500 (° C./%) showed excellent sliding property (low sliding angle). .

[Experiment 18]
≪Evaluation on long-term stability of water slide after steam treatment≫
For each measurement sample of the HfO ₂ film (hafnia film similar to the hafnia film used in Experimental Example 16) and the Al ₂ O ₃ film (alumina film similar to the alumina film used in Experimental Example 16), the following Table 13 and Table Water vapor treatment under various conditions shown in Fig. 14 was performed, and the water drop falling angle and the water contact angle were measured immediately after the water vapor treatment (within 1 hour after the water vapor treatment) and one year after the water vapor treatment.
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

Table 13 shows the water drop falling angle immediately after the steam treatment (within 1 hour after the steam treatment) and after one year from the steam treatment.
Table 14 shows the water contact angle immediately after the steam treatment (within 1 hour after the steam treatment) and after one year from the steam treatment.

As shown in Table 13, the sample treated under the water vapor treatment condition at a temperature of 40 ° C. or higher (particularly the condition where the temperature × relative humidity is 2700 (° C./%) or higher) is the water drop falling angle even after 1 year from the treatment. The increase in water was suppressed, and the sliding property was maintained for a long time.
Thus, the sample to which a certain amount of heat load is applied is also excellent in the long-term stability of the water slidability.
From this result, it was suggested that the long-term stability of the water slidability can be further improved by performing a heat treatment (for example, a heat treatment at a temperature equal to or higher than the steam treatment temperature) as a post-treatment after the steam treatment.

[Experimental Example 19]
≪Evaluation of thermal stability of water slide after steam treatment≫
The soda-lime glass substrate (SLG) and the hafnia film (HfO ₂ ) are subjected to heat treatment under various conditions (hereinafter also referred to as “post-heat treatment”) after the water vapor treatment, and the water contact angle after the post-heat treatment and The water drop falling angle was measured.
Further, as a comparison experiment, after the steam treatment, the water contact angle and the water drop falling angle when stored at room temperature (25 ° C.) for the same time as the post-heat treatment were measured.
Here, as the soda lime glass substrate and the hafnia film, the same soda lime glass substrate and the hafnia film as in Experimental Example 17 were used.
The water vapor treatment conditions were such that the measurement sample was stored for 4 days (96 hours) in a water vapor atmosphere at a temperature of 90 ° C. and a relative humidity of 50%.
Further, the post-heat treatment was performed using the same muffle furnace as in Experimental Example 1.
The temperature of the post heat treatment was 200 ° C., 300 ° C., 400 ° C., and 500 ° C., and the heat treatment time was 1 hour for each temperature.
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

FIG. 62 is a graph showing the relationship between post-heat treatment temperature, water contact angle (CA), and water drop falling angle (SA) in soda lime glass (SLG).
FIG. 63 is a graph showing the relationship between the post-heat treatment temperature, the water contact angle (CA), and the water drop falling angle (SA) in the hafnia film (HfO ₂ ).

As shown in FIGS. 62 and 63, it was confirmed that the water drop falling angle can be kept low (slidability can be stably maintained) when post-heat treatment at 300 ° C. or lower is performed.
From the results of Experimental Example 19 and Experimental Example 18, it is suggested that the long-term stability of water slidability can be further improved by performing a heat treatment at a steam treatment temperature of 300 ° C. or less as a post-treatment after the steam treatment. It was done.

[Experiment 20]
≪Experiment on adhesion force in water≫
The following measurement samples were subjected to experiments on the adhesion force in water before and after the steam treatment.
Here, the steam treatment conditions were such that the measurement sample was stored for 4 days (96 hours) in a steam atmosphere at a temperature of 90 ° C. and a relative humidity of 50%.
The conditions not described in this experimental example are the same as the conditions in Experimental example 1.

<Measurement sample>
Alumina film (Al ₂ O ₃ ): An alumina thin film similar to the alumina thin film used in Experimental Example 16 was used.
Hafnia film (HfO ₂ ) A hafnia film similar to the hafnia film used in Experimental Example 16 was used.

<Measurement method>
The friction force microscope and cantilever used in Experimental Example 16 were used to measure the adhesion force in water.
First, the surface of the measurement sample was preliminarily subjected to a static elimination treatment using an air ionizer (WINSTAT BF-2Z; Sisid Electrostatic Co., Ltd.) for 15 seconds, and the measurement sample after the static elimination treatment was submerged in water.
Next, move the probe of the cantilever closer to the surface of the measurement sample in water, and further press it against the surface (hereinafter also referred to as “approach operation”). The force acting between the probe and the sample surface was measured.
Next, after the above approach operation, after the cantilever probe is pressed against the measurement sample surface, the cantilever probe is moved away from the measurement sample surface (hereinafter also referred to as “retraction operation”). The force acting between the probe and the sample surface during the retraction operation was measured.
In addition, details of the method for measuring the adhesion force in water are described in Journal of Physical Chemistry, B, 105, 10579-10587 (2001) and Journal of Colloid and Interface Science, 307, 418-424 (2007). In the present experimental example, the same method as described in these documents was used.

<Measurement results>
64 to 71 show the measurement results of the adhesion force in water.
64 to 71, the horizontal axis represents the distance between the probe and the sample surface (Separation distance [nm]), and the vertical axis represents the force acting between the probe and the sample surface (Force [nN]). ).
In FIGS. 64 to 71, a state where the force (Force [nN]) indicated on the vertical axis is a positive value represents a state in which forces pressing each other act between the probe and the sample surface. A state in which the force (Force [nN]) shown on the vertical axis is a negative value is a state in which a pulling force is generated between the probe and the sample surface, that is, between the probe and the sample surface. This represents a state in which an adhesion force is generated between them (a state in which the probe and the sample surface stick to each other).

FIG. 64 is a graph showing the force acting between the probe and the surface of the alumina film during the approach operation performed on the surface of the alumina film before the steam treatment (in FIG. 64, “Al ₂ O ₃ , pre., Approach ").
FIG. 65 is a graph showing the force acting between the probe and the alumina film surface during the approach operation on the alumina film surface after the steam treatment (in FIG. 65, “Al ₂ O ₃ , Tre., Approach ").
FIG. 66 is a graph showing the force acting between the probe and the alumina film surface in the process of performing the retraction operation on the alumina film surface before the steam treatment (in FIG. 66, “Al ₂ O ₃ , pre., Retraction ”).
FIG. 67 is a graph showing the force acting between the probe and the alumina film surface during the retraction operation on the alumina film surface after the steam treatment (in FIG. 67, “Al ₂ O ₃ , tre., Retraction ”).

As shown in FIGS. 64 and 65, regarding the behavior of force during the approach operation, there was no significant difference between the alumina film before the steam treatment and the alumina film after the steam treatment.
On the other hand, as shown in FIGS. 66 and 67, regarding the behavior of the force during the retraction operation, there was a large difference between the alumina film before the steam treatment and the alumina film after the steam treatment.
As shown in FIG. 67, in the alumina film after the steam treatment, a larger adhesion force was generated between the probe and the alumina film surface than the alumina film before the steam treatment (FIG. 66). This is because the surface of the alumina film is made water-sliding by the water vapor treatment, so that it is difficult for water to exist between the probe and the surface of the alumina film, and the probe and the surface of the alumina film are strongly adhered to each other. Therefore, it is guessed.

FIG. 68 is a graph showing the force acting between the probe and the sample surface during the approach operation on the hafnia film surface before the steam treatment (in FIG. 68, “HfO ₂ , pre. , "Approach").
FIG. 69 is a graph showing the force acting between the probe and the sample surface during the approach operation on the surface of the hafnia film after the water vapor treatment (in FIG. 69, “HfO ₂ , tre. , "Approach").
FIG. 70 is a graph showing changes in the force acting between the probe and the sample surface during the retraction operation on the surface of the hafnia film before the steam treatment (in FIG. 70, “HfO ₂ , pre., retraction ”).
FIG. 71 is a graph showing a change in force acting between the probe surface and the sample surface during the retraction operation on the surface of the hafnia film after the steam treatment (in FIG. 71, “HfO ₂ , tre., retraction ”).

As shown in FIGS. 68 and 69, with respect to the behavior of the force during the approach operation, there was no significant difference between the hafnia film before the steam treatment and the hafnia film after the steam treatment.
On the other hand, as shown in FIG. 71, in the hafnia film after the water vapor treatment, a larger adhesion force was generated between the probe and the surface of the hafnia film than in the hafnia film before the water vapor treatment (FIG. 70). The reason is that the surface of the hafnia film is made water-slidable by the water vapor treatment, so that it is difficult for water to exist between the probe and the surface of the hafnia film, and the probe and the surface of the hafnia film are strongly adhered to each other. Therefore, it is guessed.

The disclosures of Japanese application 2009-205175 and Japanese application 2010-028083 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

Preparing an inorganic structure material;
A steam treatment step for reducing a water droplet falling angle on the surface of the inorganic structure material by steaming the inorganic structure material;
The manufacturing method of the inorganic structure which has this.
2. The method for producing an inorganic structure according to claim 1, wherein the steam treatment is performed by exposing the inorganic structure material to a steam atmosphere having a temperature of 30 ° C. to 100 ° C. and an absolute humidity of 15 g / m 3 or more.
The method for producing an inorganic structure according to claim 1, wherein the steam treatment is performed by exposing to a steam atmosphere having a product of temperature (° C) and relative humidity (%) of 2000 ° C ·% or more and 10,000 ° C ·% or less.
The method for producing an inorganic structure according to claim 1, further comprising a pretreatment step of performing a pretreatment for removing organic substances on the surface of the inorganic structure material with respect to the inorganic structure material before the water vapor treatment step.
The method for producing an inorganic structure according to claim 4, wherein the pretreatment is at least one of heat treatment at 100 ° C or higher, ultrasonic cleaning treatment, and ultraviolet irradiation treatment.
The manufacturing method of the inorganic structure of Claim 1 which has the post-processing process which performs the heat processing more than the temperature of the said water vapor | steam and the 300 degreeC or less as a post-processing with respect to the said inorganic structure raw material after the said water vapor treatment process.
The method for producing an inorganic structure according to claim 1, wherein the inorganic structure material includes at least one selected from a metal, an alloy, an inorganic oxide, and glass.
The inorganic structure material is an inorganic solid containing at least one selected from stainless steel, soda lime glass, and quartz glass, or at least one selected from the group consisting of alumina, ceria, titania, hafnia, and silica. The method for producing an inorganic structure according to claim 1, wherein the inorganic thin film contains an inorganic thin film.
A coating film forming step in which a coating liquid containing an inorganic oxide precursor is coated on a support to form a coating film;
A heat treatment step of heat-treating the formed coating film at a temperature of 300 ° C. or higher;
A steam treatment step for reducing a water droplet falling angle on the surface of the heat-treated coating film by steam-treating the heat-treated coating film;
The manufacturing method of the inorganic thin film which has.
An inorganic structure in which the density of resistance points that inhibit sliding of water droplets on the surface is 10 pieces / 30 mm 2 or less.
The inorganic structure according to claim 10 obtained by steam treatment.
The manufacturing method of the inorganic structure of Claim 10 containing at least 1 sort (s) selected from a metal, an alloy, an inorganic oxide, and glass.
An inorganic thin film containing at least one selected from the group consisting of at least one selected from stainless steel, soda-lime glass, and quartz glass, or from the group consisting of zirconia, alumina, ceria, titania, hafnia, and silica. The inorganic structure according to claim 10.
The inorganic structure according to claim 10, wherein a contact angle with water is 30 ° or more and a water drop falling angle is 40 ° or less.
Using a Si 3 N 4 cantilever having a spring constant in the thickness direction of 0.05 N / m, a region where the friction force measured by a friction force microscope is 10 nN or less under a pressing pressure of 14 nN,
as well as,
Using a cantilever made of Si 3 N 4 having a spring constant in the thickness direction of 0.05 N / m and at a pressing pressure of 14 nN, at least one of the regions having a dynamic friction coefficient measured by a friction force microscope of 1.0 or less An inorganic structure containing on the surface.
The inorganic structure according to claim 15 obtained by steam treatment.
The inorganic structure according to claim 16, wherein an average value of the frictional force on the surface is lower than that before the steam treatment.
The inorganic structure according to claim 16, wherein an average value of the frictional force on the surface is reduced to half or less than that before the steam treatment.
An inorganic thin film containing at least one selected from the group consisting of at least one selected from stainless steel, soda-lime glass, and quartz glass, or from the group consisting of zirconia, alumina, ceria, titania, hafnia, and silica. The inorganic structure according to claim 15.
The inorganic structure according to claim 15, wherein the contact angle with water is 30 ° or more and the water drop falling angle is 40 ° or less.