JP6164448B2 - Manufacturing method of oxide film - Google Patents

Description

The present invention relates to a process for the preparation of an oxide skin layer having convex portions on the surface.

  An uneven shape is formed on the surface of a glass plate such as a vehicle windshield to give various functions. For example, many techniques are known in which a water-repellent material is formed into a thin film on the surface of a glass plate to prevent raindrop removal and contamination. The water repellency of the glass plate is strongly influenced by the surface structure of the provided water repellent material. For example, the surface of the water-repellent material is artificially formed with a concavo-convex structure like a lotus leaf, and an air gap is formed between the water droplet and the water-repellent material, thereby increasing the contact angle with water droplets and water. It is known that the sliding property is improved. This phenomenon is called the Lotus effect.

  As a technology for applying a water-repellent material in a thin film form on a substrate, a method of dissolving and coating a water-repellent resin material in a solvent, or hydrolyzing and polycondensing a silicon alkoxide having a water-repellent functional group by a sol-gel reaction There is a method of forming a film.

  Further, it has been proposed to form a concavo-convex structure on the surface of the water repellent material with the aim of the lotus effect. For example, as shown in Non-Patent Document 1, in a sol-gel method using two types of silicon alkoxide, hydrochloric acid as a catalyst is mixed with each to start polymerization to form a sol. Thereafter, these are mixed, coated on a glass substrate, dried and baked to obtain a silica thin film having irregularities on the surface.

  However, the concavo-convex structure is formed by utilizing phase separation of two types of silicon alkoxides having different properties. For this reason, there are few choices of a thin film material. Moreover, the uneven structure to be formed differs depending on the selection of the thin film material, and there is a problem that it is difficult to control the uneven structure.

  As shown in Patent Document 1, a solution obtained by mixing thermally decomposable resin fine particles with water glass is applied on a substrate, and the resin fine particles on the surface are thermally decomposed in a baking step. As a result, a film having fine pores on the surface is obtained with the portions where the resin fine particles existed as pores.

  As shown in Patent Document 2, two or more polymer solutions are mixed to form a mixed polymer film on a substrate. Thereafter, at least one kind of polymer is dissolved and removed. Micropores are formed in the portion where the removed polymer was present.

  In Patent Documents 1 and 2, in addition to the final target coating material, a hole forming material for forming the surface uneven structure is separately required. Moreover, this pore forming material cannot be reused. Further, it is difficult to completely remove the hole forming material, and there is a problem that the hole forming material remains in the film.

  As shown in Patent Document 3, a surface concavo-convex surface having water repellency is obtained by curing and polymerizing a fluorine-containing polymer and a curing agent in a mold mold having fine undulations by a sol-gel method. To form a structure with

  As shown in Patent Document 4, a self-assembled monomolecular film formed on a substrate is exposed by diffracting laser light using a film with an uneven surface called a master and making it interfere. Then, a pattern such as irregularities is formed on the substrate surface.

  However, in the techniques disclosed in Patent Documents 3 and 4, it is necessary to separately prepare a special jig such as a mold or a master in order to form a concavo-convex shape on the surface. A molding machine, a laser device, etc. are required, and manufacturing equipment costs.

JP 2005-81292 A JP 2002-363501 A JP 2008-162190 A JP 2005-331564 A

K.MAKITA et al., “Surface Morphology of Silica Films Derived by the Sol-Gel Method and Its Application to a Water Repellet Glass” Journal of Ceramic Society of Japan 105 [11] 1012-1017 (1997)

The present invention has been made in view of such circumstances, and an object thereof is to provide a method of manufacturing an oxide skin layer capable of forming an uneven surface of simplicity the coating material.

Method of manufacturing an oxide film of the present invention is a manufacturing method of an oxide film formed from a raw material solution containing A Rukokishido,
By forming water droplets composed of a catalyst and water on the surface of the raw material solution supplied in a thin film form on the base material, the sol-gel reaction of the alkoxide proceeds from the water droplets as a starting point, and the water droplets are minutely present. forming the oxide film with by forming a convex portion formed of an inorganic oxide polymer,
The raw material solution is a solution having a low affinity with the water droplets, and includes the alkoxide, a hydrophobic solvent, and an amphiphilic substance.

According to the present invention, the surface of the raw material solution consisting of A Rukokishido and hydrophobic solvent, by forming a water droplet consisting of catalyst and water, and non-uniformly positioned a catalyst on the surface of the raw material solution. Starting from the catalyst in the water droplet, the sol-gel reaction of the alkoxide is advanced to form an oxide film having fine convex portions dispersed and formed on the surface. For this reason, the oxide film which has a surface uneven structure can be formed simply.

It is explanatory drawing which shows the manufacturing method of an oxide film, Comprising: The upper figure of FIG. 1 is a figure which shows the state when a base material is put on the water vapor | steam containing a catalyst, The middle figure of FIG. It is a figure which shows a state when a water droplet is formed, and the lower figure of FIG. 1 is a figure which shows a state when the oxide film which has a micro convex part is formed by sol-gel reaction. It is explanatory drawing of the film-forming apparatus. It is explanatory drawing of a humidifier and an absorber. The electron micrograph of the oxide film of Example 1 is shown. The electron micrograph of the oxide film of Example 2 is shown.

Method of manufacturing an oxide film of the present invention, the presence of a catalyst, when the progress of the sol-gel reaction of A Rukokishido, the surface of the raw material solution containing alkoxide, by heterogeneously feeding catalyst, heterogeneous sol-gel reaction It is characterized by being advanced to. Without using a special material other than the coating material, and without using a special jig such as a mold, it is possible to simply form an oxide coating having a minute convex portion.

  When the oxide film is made of silica, the oxide film is generally formed by hydrolysis and polycondensation of silicon alkoxide by a sol-gel method. The reaction generally proceeds as follows.

  First, silicon alkoxide is hydrolyzed. R in the formula (1) represents an alkyl group.

nSi (OR) ₄ + nH ₂ O → nSi (OH) (OR) ₃ + nROH (1)
This hydrolysis reaction is promoted by the catalytic action of a catalyst such as an acid or an alkali, and Si (OH) ₄ is generated as shown in the following formula.

nSi (OR) ₄ + 4nH ₂ O → nSi (OH) ₄ + 4nROH (2)
A polycondensation reaction in which water is eliminated occurs between the hydroxides Si (OH) ₄ generated in the formula (2) as shown in the following formula.

Si (OH) ₄ + Si (OH) ₄ → (OH) ₃ Si-O-Si (OH) ₃ + H ₂ O (3)
Finally, silica represented by the composition formula SiO ₂ is formed.

General method for creating an oxide film using a sol-gel reaction, in a solution containing A Rukokishido, adding an acid or an alkali as a catalyst, the raw material solution is fully deployed on the substrate prior to gelation The oxide film is formed by advancing the polycondensation reaction on the substrate. In general, since the sol-gel reaction proceeds uniformly in the film, the surface of the formed film is smooth.

In contrast, the present invention, as shown in the upper diagram of FIG. 1, the A Rukokishido and substrate 3 to the raw material solution A was formed on the surface as a thin film made of a hydrophobic solvent, an atmosphere of steam B containing catalyst The water vapor B is adhered to the surface of the raw material solution A.

  As shown in the middle diagram of FIG. 1, the water vapor B is condensed to form water droplets b. At this time, the catalyst is dissolved in the water droplet b, and the catalyst concentration is increased. Thereby, a catalyst is supplied to an alkoxide nonuniformly. For this reason, as shown in the lower diagram of FIG. 1, an oxide film 1 in which a sol-gel reaction of an alkoxide proceeds on the substrate 3 with the catalyst in the water droplet b as a nucleus and a plurality of minute convex portions 2 are dispersed on the surface. Is formed.

Here, by forming water droplets on the surface of the raw material solution, the sol-gel reaction of the alkoxide in the raw material solution proceeds from the water droplet as a starting point. Raw material solution, because consisting of A Rukokishido a hydrophobic solvent, a low affinity with a drop of water. For this reason, water droplets are not easily mixed with the raw material solution, and remain on the surface of the raw material solution for a certain period of time. During this time, the catalyst in the water droplets contacts the alkoxide in the raw material solution to advance the sol-gel reaction of the alkoxide. The water droplets are dispersed independently on the surface of the raw material solution. For this reason, on the surface of the raw material solution, the catalyst is dispersed at the locations where the water droplets are present, and is present non-uniformly.

  The alkoxide in the raw material solution comes into contact with the catalyst present in a non-uniformly dispersed manner, and the sol-gel reaction exemplified by the above formulas (1) to (3) is promoted. The sol-gel reaction proceeds preferentially at the location of water droplets in the raw material solution, and the raw material solution is solidified.

  At this time, although a reason is not certain, a minute convex part is formed in the location of the water droplet in the raw material solution. Presumably, the water droplets try to maintain their shape due to the surface tension of the water droplets, so that the locations where the water droplets exist are solidified as minute convex portions. Further, when the reaction at the water droplet portion proceeds, the raw material solution containing the alkoxide gathers from the periphery of the water droplet one after another toward the water droplet, and the reaction proceeds intensively at the water droplet portion. This is also considered to influence the formation of the minute projections. The sol-gel reaction also proceeds gradually in the portions where no water droplets exist, and the entire raw material solution gels to form a thin film.

  Now, the method for supplying water droplets to the surface of the raw material solution is not particularly limited, and examples thereof include the following methods.

  As shown in the upper diagram of FIG. 1, the base material 3 to which the raw material solution A is supplied in a thin film is placed in an atmosphere of water vapor B. Next, as shown in the middle diagram of FIG. 1, the water vapor B is cooled to form water droplets b on the surface of the raw material solution A. It is preferable to form the water droplets containing the catalyst by causing the water vapor to condense due to a temperature change in an atmosphere where the catalyst and the water vapor are present. It is preferable that the water droplets are formed on the surface of the raw material solution by condensation of the water vapor in the cooling portion of the raw material solution cooled by evaporation of the hydrophobic solvent. Water vapor is finely condensed to make the minute protrusions of the oxide film finer. In the case where the oxide film is water repellent, the water repellency can be further improved by refining the minute protrusions. When the oxide film is hydrophilic, the hydrophilicity can be further improved by miniaturizing the minute protrusions. Further, by adjusting the dispersibility of the hydrophobic solvent by adjusting the time from the stirring of the raw material solution to the application, etc., it is possible to freely adjust the level of refinement of the minute protrusions of the oxide film.

  In order to cool the water vapor B in the vicinity of the substrate 3, for example, the temperature of the raw material solution A is changed low. In order to change the temperature of the raw material solution A low, for example, a volatile hydrophobic solvent is used as the hydrophobic solvent contained in the raw material solution A. In this case, the hydrophobic solvent begins to volatilize as soon as it is fed onto the substrate. Due to the heat of vaporization during volatilization, the temperature of the hydrophobic solvent is lowered. The water vapor attached to the surface of the raw material solution is condensed and aggregates to form water droplets. Even if a volatile solvent is not used as the hydrophobic solvent, water vapor can be condensed and water droplets can be formed by cooling the temperature of the raw material solution itself by other means.

  The vaporization temperature of the volatile hydrophobic solvent is preferably 10 to 80 ° C. The raw material solution can be cooled by the heat of vaporization of the hydrophobic solvent, and water vapor containing the catalyst can be condensed. If the vaporization temperature of the hydrophobic solvent is less than 10 ° C., the hydrophobic solvent is too volatile and may be difficult to handle. When the vaporization temperature of the hydrophobic solvent exceeds 80 ° C., the hydrophobic solvent is unlikely to volatilize, and water droplets may evaporate during the sol-gel reaction.

  In order to cool the water vapor by changing the temperature of the atmosphere to a low temperature, for example, the atmosphere is cooled by a cooling means. Preferably, the atmosphere is filled with water vapor to a level close to the saturated water vapor pressure, and the atmosphere is cooled from the state by the cooling means.

  In this case, for example, the relative humidity (RH) of the atmosphere is preferably a humidity close to saturated water vapor, for example, 90% or more. In this case, by changing the temperature low, water vapor attached to the raw material solution is condensed and water droplets are easily formed. If the relative humidity of the atmosphere is too low, there is a risk that it will be difficult for water vapor to condense due to temperature changes.

  Moreover, the base material supplied with the raw material solution on the surface may be disposed in the cooling chamber, and water vapor may be introduced into the cooling chamber to cool the water vapor. In this case, the temperature of the cooling chamber is preferably lower than the temperature of water vapor before introduction, for example, about 5 to 20 ° C.

  It is also possible to form water droplets on the surface of the raw material solution by spraying water containing the catalyst on the surface of the raw material solution with a spray, a sprayer or the like.

  When water droplets are supplied to the surface of the raw material solution, the sol-gel reaction of the alkoxide in the raw material solution proceeds from the water droplets due to the action of the catalyst in the water droplets, and minute protrusions are formed at the locations of the water droplets. . In order to form a minute convex part at the location where the water droplet exists, it is necessary to hold the water droplet on the surface of the raw material solution for a certain period of time to maintain a state where the catalyst is unevenly arranged on the surface of the raw material solution. preferable. A preferred embodiment for holding the water droplets on the surface of the raw material solution for a certain period of time will be described.

  In order to keep the water droplets on the surface of the raw material solution for a certain period of time, the size of the water droplets supplied to the surface of the raw material solution is preferably 100 to 5000 nm. From the water droplet of this size, it becomes easier to generate a minute convex portion. When the size of the water droplet is excessively small, it is difficult to control the water vapor concentration and temperature, or the water droplet may evaporate during the reaction. If the size of the water droplet is too large, the water droplets may be combined to make it difficult to form a minute convex portion.

Raw material solution, the A Rukokishido a solution of a hydrophobic solvent. The water droplets supplied to the surface of the raw material solution are not dissolved in the raw material solution but separated from the raw material solution, and the shape of the water droplets is maintained on the surface of the raw material solution for a certain time, for example, for a few seconds. Good. Therefore, it is necessary to dissolve the alkoxide with a hydrophobic solvent having a low affinity for water droplets to obtain a raw material solution.

  The specific gravity of the hydrophobic solvent is preferably larger than the specific gravity of water. The raw material solution containing the hydrophobic solvent is heavier than the water droplet, and can stably hold the water droplet on the surface of the raw material solution. Since the specific gravity of water is about 1, the specific gravity of the hydrophobic solvent is preferably larger than 1.

Heavy hydrophobic solvent than the specific gravity of water, chloroform, and be composed of one or more selected from the group consisting of dichloro-pentafluoro propane preferred. Among these, in order to supply water droplets to the surface of the raw material solution, when adopting a method in which water vapor is condensed on the hydrophobic solvent by heat of vaporization, it is preferable to use chloroform or the like as the hydrophobic solvent having volatility. .

  In addition, if the water droplets are held on the surface of the raw material solution for a certain period of time, it is also possible to use a hydrophobic solvent having a specific gravity that is equal to or lower than the specific gravity of water.

  Moreover, in order to hold water droplets on the surface of the raw material solution, the raw material solution preferably contains an amphiphilic substance. Amphiphiles have a hydrophilic part and a hydrophobic part. The amphiphile covers the surface of the water droplet with the hydrophilic portion facing the inside of the water droplet and the hydrophobic portion facing the outside of the water droplet. It is possible to prevent water droplets from contacting and growing. For this reason, it is possible to maintain a state in which fine water droplets are dispersed on the surface of the raw material solution.

  Specific examples of the amphiphilic substance include lecithin, polymethyl methacrylate, a block copolymer of polyethylene glycol and polypropylene glycol, and a phosphate ester surfactant. Of these, lecithin is preferred.

  The concentration of the amphiphile contained in the raw material solution is preferably 0.01 mol / L or more and 0.3 mol / L or less. When the concentration of the amphiphilic substance is excessively thin, the effect of including the amphiphilic substance in the raw material solution is diminished, and there is a possibility that water droplets cannot be stably held on the surface of the raw material solution. When the concentration of the amphiphile is excessively high, there is a possibility that it remains in the oxide film.

A Rukokishido is, if synthesized inorganic oxide polymer by a sol-gel method is not particularly limited. A Rukokishido, in addition to the inorganic portion, may include an organic moiety. If it contains organic moieties in A Rukokishido the organic moiety by a sol-gel reaction is desorbed from the inorganic oxide polymer. After completion of the sol-gel reaction, the organic part may be washed with a solvent.

A Rukokishido may if there is a metal alkoxide. The metal alkoxide is, for example, selected from the group consisting of silicon (Si) alkoxide, Ti alkoxide, U alkoxide, Tn alkoxide, Zr alkoxide, Ce alkoxide, Sn alkoxide, Cu alkoxide, Sn alkoxide, Zn alkoxide, Al alkoxide, and Sc alkoxide. Consists of one or more. Of these, silicon alkoxide is preferable from the viewpoint of use.

  As the silicon alkoxide, it is preferable to use one or more selected from the group of tetraethyl orthosilicate, triethoxy 1H, 1H, 2H, 2H-tridecafluorooctylsilane and triethoxyoctylsilane.

A Rukokishido includes a hydrophilic, there is a water repellent. If A Rukokishido is hydrophilic, oxide film has hydrophilicity. If A Rukokishido is water repellency, oxide film has water repellency. A Rukokishido, for example, in the case of hydrophilic silicon alkoxide, the hydrophilic silicon alkoxide, such as tetraethyl orthosilicate and the like. Examples of the water-repellent silicon alkoxide include triethoxy 1H, 1H, 2H, 2H-tridecafluorooctylsilane and the like.

The concentration of A Rukokishido in the raw material solution may be less than 0.5 mol / L or more 5 mol / L, further preferably not more than 1 mol / L or more 2 mol / L. If the lower limit of the concentration of A Rukokishido is too small, there is a possibility that the oxide film is hardly generated. If the upper limit of the concentration of A Rukokishido is excessive, it may become less soluble in a hydrophobic solvent.

  The raw material solution is supplied as a thin film on the substrate. Examples of the method for supplying the raw material solution on the substrate in a thin film include, but are not limited to, a spin coating method, a doctor blade method, a dip method, and the like.

The thickness of the raw material solution supplied on the substrate is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 30 μm or less. When the thickness of the raw material solution is too small, it may be difficult to form a continuous thin-film oxide film. When the thickness of the raw material solution is too large, difficult to cure the portion of the A Rukokishido close to the substrate surface of the raw material solution.

  The substrate to which the raw material solution is supplied preferably has a smooth surface. This is because the raw material solution is supplied in a uniform thickness on the substrate. Although the material of a base material is not specifically limited, For example, it is good in it being a glass substrate.

Catalyst contained in water droplets, to promote the sol-gel reaction of A Rukokishido. This catalyst is volatile and may be water-soluble. This catalyst is preferably composed of an acid or an alkali, and is preferably a gaseous acid or alkali. Examples of the acid used as the catalyst include hydrogen chloride, nitric acid, and hydrogen fluoride. For example, ammonia or the like can be used as the alkali as the catalyst.

  The concentration of the catalyst in the atmosphere containing water vapor is preferably 0.1 ppm or more and 5 ppm or less, and more preferably 0.5 ppm or more and 1 ppm or less. If the concentration of the catalyst is excessively thin, the sol-gel reaction is slow, and an oxide film may not be formed, or even if an oxide film is formed, it may be difficult to form minute protrusions. If the concentration of the catalyst is excessively high, the reaction may be too fast and it may be difficult to form minute convex portions.

  The temperature of the atmosphere when the sol-gel reaction proceeds is preferably 10 ° C. or higher and 80 ° C. or lower. If the temperature of the atmosphere is excessively low, the progress rate of the reaction is slow, and there is a possibility that the minute protrusions are hardly formed. When the temperature of the atmosphere is excessively high, there is a risk that the progress of the reaction will be too fast, making it difficult to form microprojections or evaporating water droplets.

On the surface of the generated oxide film, minute convex portions are formed in a dispersed manner. The structure such as the size, shape, pitch, and aspect ratio of the minute protrusions can be variously changed depending on the balance and speed of the water droplet growth reaction and the sol-gel reaction. For example, the temperature of the atmosphere, humidity, and these changes speed, the concentration of the catalyst in water droplets, the concentration of A Rukokishido in the raw material solution, the concentration of amphiphile in water droplets, by controlling the thickness of the raw material solution It is possible to change the structure of the minute projections in various ways. These various conditions are related in a complicated manner, and the structure such as the size and pitch of the minute projections changes. For this reason, the relationship between the structure of the minute protrusions and various conditions cannot be generally stated, but is as follows, for example.

  For example, when the temperature of the atmosphere is high, the speed of the sol-gel reaction is increased, the size of the minute projections is small, and the pitch tends to be dense. When the temperature of the atmosphere is low, the speed of the sol-gel reaction is slow, and there is a tendency that minute protrusions having a relatively large pitch and a rough pitch are formed.

  When the humidity of the atmosphere is high, the amount of water vapor containing the catalyst increases in the atmosphere, so that water droplets grow relatively large and the size of the minute convex portions tends to increase. When the humidity is low, the amount of water vapor containing the catalyst is reduced in the atmosphere, and the size of the minute projections tends to be small and the pitch tends to be large.

  When the concentration of the catalyst in the water droplet is high, the size of the minute convex portion tends to increase. When the concentration of the catalyst is low, the size of the minute convex portion tends to be small.

If a high concentration of A Rukokishido the raw material solution, the size of minute projections tends to increase. If the low concentration of A Rukokishido the raw material solution, the size of minute projections tends to decrease.

  When the concentration of the amphiphile in the raw material solution is low, water droplets grow and the size of the microprojections tends to increase.

  When the thickness of the raw material solution on the substrate is large, the size of the minute projections tends to increase. When the thickness of the raw material solution is thin, the size of the minute projections tends to be small.

  Also, in order to increase the ratio of the height of the minute protrusions to the pitch of the minute protrusions (aspect ratio), the viscosity of the raw material solution may be lowered to extend the life of the water droplets. For example, 1) lowering the alkoxide concentration 2) Increase the amphiphile concentration or / and 3) increase the catalyst concentration.

  The above oxide film manufacturing method can be performed using, for example, a film forming apparatus 7 shown in FIG. The film forming apparatus 7 includes a container 71 having an internal space 70, and a raw material introduction pipe 73, a catalyst introduction pipe 74, and an exhaust pipe 75 that are provided in the container 71 and open to the internal space 70. The raw material introduction pipe 73, the catalyst introduction pipe 74, and the exhaust pipe 75 are provided with flow rate adjusting means so that the flow rate of the fluid flowing through each pipe can be adjusted. The base material 3 is disposed at the bottom in the container 71.

  The raw material introduction pipe 73 supplies the raw material solution A onto the base material 3. The catalyst introduction pipe 74 supplies the water vapor B containing the catalyst to the internal space 70 of the container 71. The exhaust pipe 75 exhausts the gas in the internal space 70 to the outside.

  The container 71 only needs to adjust the humidity of the internal space 70. The container 71 shown in FIG. 2 has a sealed space surrounded by a bottomed container 71a having an opening and a lid 71b covering the opening, but may be an open space. The base material 3 is disposed inside the container 71. The raw material solution A is supplied from the raw material introduction pipe 73 to the surface of the base material 3.

  The raw material solution A may be left as it is and wait for it to spread on the surface of the substrate 3, but may be spread in a thin film by, for example, a spin coating method or a doctor blade method. In the spin coater method, the base 3 is fixed on the turntable 76 and the turntable 76 is rotated when the raw material solution A is supplied onto the base 3 from the raw material introduction pipe 73. The raw material solution A on the base material 3 spreads in a thin film shape by centrifugal force due to rotation. Moreover, you may spread the raw material solution A on the base material 3 by a doctor blade method.

  Of these, spin coating is preferred. This is because the spin coating method can form water droplets on the surface of the raw material solution A while rotating the base material 3 to spread the raw material solution A on the base material 3 in a thin film shape, and has good workability.

  Steam B containing the catalyst is supplied to the internal space of the container 71 through the catalyst introduction pipe 74. The base material 3 supplied with the raw material solution A on the surface may start the supply of the water vapor B after stopping its rotation. Moreover, you may supply the water vapor | steam B, rotating the base material 3. FIG. When the raw material solution A is supplied on the substrate 3 in a thin film shape, the water vapor B adheres to the surface. In order to change the temperature of the raw material solution A to a low temperature, when a volatile solvent having a relatively low vaporization temperature is used as the hydrophobic solvent contained in the raw material solution A, the raw material solution A is naturally cooled by the heat of vaporization of the hydrophobic solvent. It changes to low temperature.

  Moreover, you may cool the base material 3 with an external cooling means. The external cooling means is a cooling means provided outside the container 71, and examples thereof include a refrigerant, a cooling device provided on the peripheral wall of the container 71, and the like. The refrigerant is cooled outside the container 71 and then introduced into the container 71 to cool the substrate.

  Further, the film formation apparatus 7 is supplied with water vapor B containing a catalyst through a catalyst introduction pipe 74. The means for producing the water vapor B containing the catalyst is not particularly limited. For example, as shown in FIG. 3, a humidifier 5 for containing water vapor in the carrier gas and an absorber 6 for bringing the water vapor into contact with the catalyst may be used.

  The humidifier 5 is of Muenke type, the absorption container 52 containing the water 51, the discharge port 54 opened at the top of the absorption container 53, and the tip of the humidifier 5 into the water 51 so as to introduce the carrier gas directly into the water 51. The inlet pipe 56 is opened. As the carrier gas, for example, air or nitrogen may be used. When the carrier gas is supplied into the water 51, the carrier gas contains water and water vapor B is generated. The generated water vapor B is discharged from the absorption container 52 through the discharge port 54 and supplied to the next absorber 6.

  The absorber 6 includes a bottomed cylindrical absorption tank 60 having an opening, a lid body 62 that closes the opening of the absorption tank 60, an introduction pipe 63 that is fixed to the lid body 62 and opens into the internal space of the absorption tank 60, It has a supply pipe 64 and a lead-out pipe 65. The introduction pipe 63 is connected to the outlet 54 of the humidifier 5, and introduces the water vapor B generated by the humidifier 5 into the internal space of the absorption tank 60. The supply pipe 64 supplies a catalyst solution containing a catalyst to the internal space of the absorption tank 60 and causes the water vapor B introduced into the internal space to contain the catalyst. The water vapor B containing the catalyst is led out from the absorption tank 60 through the lead-out pipe 64 and supplied to the film forming apparatus 7.

  Moreover, in order to include a catalyst in water vapor, a glass gauze containing a catalyst solution may be used. Glass gauze 66 containing a catalyst solution may be spread in the absorber 6 shown in FIG. 3 to introduce water vapor into the absorber 6.

  The oxide film produced by the method for producing an oxide film of the present invention has a plurality of minute convex portions. The minute projections are dispersed on the surface of the oxide film. Various functions can be exhibited by variously adjusting the size, pitch, aspect ratio, shape, and the like of the minute protrusions.

  For example, when the oxide film has water repellency, in order to improve the water repellency performance of the minute protrusions on the surface of the oxide film, a lotus structure may be formed on the minute protrusions. In this case, the size of the minute convex part is preferably smaller than the size of the contact part of the water droplet to the film surface. It is preferable that the size of the minute protrusions is not more than the size of the water droplets. Here, the size of the minute projections means the maximum width of the projection area of the minute projections when the oxide film is projected from the vertical direction. When the size of the minute convex portion is within the above range, it has a lotus effect and can exhibit water repellency.

  If the contact angle of the minute protrusion is larger than 0 °, various functions can be given to the surface of the coating. For example, when the oxide film has water repellency, the contact angle of the minute protrusions on the surface of the oxide film is preferably 150 ° or more. In this case, the water-repellent performance of the water-repellent oxide film is further improved.

  The aspect ratio of the minute protrusions (ratio of the height to the pitch interval of the minute protrusions) is preferably 0.5 or more. In this case, the water repellency of the oxide film is increased.

  Moreover, it is preferable that the oxide film has transparency. By covering the transparent glass substrate with the oxide film having transparency, a minute convex portion can be attached to the surface of the glass substrate without impairing the transparency of the glass substrate. In order to ensure the transparency of the oxide film, the minute protrusions are preferably smaller than the wavelength of visible light. Specifically, the size of the minute protrusions is preferably 500 nm or less, and more preferably 400 nm or less. In this case, the minute projections can maintain transparency without hindering transmission of visible light.

  By adjusting the size of the minute projections as described above, the oxide film has water repellency, antifouling properties, abrasion resistance, transparency, ultraviolet reflectivity, antibacterial properties, deodorizing properties, antistatic properties, etc. Various functions can be added.

Oxide film of the present invention is a film comprising an inorganic oxide polymer, an oxide obtained by advancing the sol-gel reaction for A Rukokishido. The oxide film is made of, for example, SiO ₂ (silica) or a metal oxide. The metal oxide constituting the oxide film is, for example, TiO ₂ , UO ₂ , TnO ₂ , ZrO ₂ , CeO ₂ , SnO ₂ , SiO ₂ , CuO, SnO ₂ , ZnO, Al ₂ O ₃ , Sc ₂ O _3. ZnTiO ₃ , SrTiO ₃ , BaZrO ₃ , CaSnO _{3 and the} like are preferable.

  The oxide film of the present invention is used, for example, formed on a base material such as a glass substrate. A glass substrate on which an oxide film is formed is used as, for example, vehicle glass, residential or architectural glass, and a camera lens.

  The oxide film of the present invention has various uses. For example, it can be used as a water-repellent film, antifouling film, abrasion-resistant film, UV reflective coating film, antibacterial agent, deodorant, dye-sensitized solar cell, conductive film, antistatic film, etc. is there.

Example 1
In Example 1, an oxide film was produced by the following method.

  Tetraethyl orthosilicate (TEOS) as a silicon alkoxide and lecithin as an amphiphile were dissolved in chloroform as a hydrophobic solvent in the container to prepare a raw material solution A. The concentration of TEOS in the raw material solution A was 1.6 mol / L, and the concentration of lecithin was 0.1 mol / L.

  A humidifier, glass gauze, and a film forming apparatus were prepared. As shown in FIG. 3, the humidifier 5 is a Muenke type, so that the absorption container 52 containing the water 51, the discharge port 54 opened at the top of the absorption container 52, and the carrier gas are directly introduced into the water 51. And an introduction pipe 56 whose tip is opened in the water 51. Nitrogen gas was used as the carrier gas. When the carrier gas was supplied into the water 51 at a flow rate of 500 cc / min, the carrier gas contained water and water vapor B was generated. The generated water vapor B was discharged from the absorption container 52 through the discharge port 54 and supplied to the next absorber 6.

  The absorber 6 includes a bottomed cylindrical absorption tank 60 having an opening, a lid body 62 that closes the opening of the absorption tank 60, and an introduction pipe 63 that is fixed to the lid body 62 and opens into an internal space 67 of the absorption tank 60. , A supply pipe 64 and a lead-out pipe 65, and a glass gauze 66 spread inside the absorption tank 60. The introduction pipe 63 is connected to the outlet 54 of the humidifier 5, and introduces the water vapor B generated by the humidifier 5 into the internal space 67 of the absorption tank 60. The supply pipe 64 supplied the catalyst solution 61 containing the catalyst to the internal space 67 of the absorption tank 60 and soaked the catalyst into the glass gauze 66. The water vapor B introduced into the internal space 67 was in contact with the glass gauze 66 soaked with the catalyst and contained the catalyst. The water vapor B containing the catalyst was led out from the absorption tank 60 through the lead-out pipe 65 and supplied to the film forming apparatus.

  As shown in FIG. 2, the film forming apparatus 7 includes a container 71 having an internal space 70, and a raw material introduction pipe 73, a catalyst introduction pipe 74, and an exhaust pipe 75 that are provided in the container 71 and open to the internal space 70. Have. The raw material introduction pipe 73 is a female pipette. The catalyst introduction pipe 74 and the exhaust pipe 75 are provided with a mass flow as a flow rate adjusting means (not shown) so that the flow rate of the fluid flowing through each pipe can be adjusted.

  The raw material introduction pipe 73 supplies the raw material solution A onto the base material 3. The catalyst introduction pipe 74 supplies the water vapor B containing the catalyst to the internal space 70 of the container 71. The exhaust pipe 75 exhausts the gas in the internal space 70 to the outside.

  The container 71 only needs to adjust the humidity of the internal space 70. The container 71 includes a bottomed container 71a having an opening and a lid 71b that covers the opening. The internal space 70 surrounded by the bottomed housing portion 71a and the lid body 71b forms a sealed space. A turntable 76 is disposed at the bottom of the container 71. On the turntable 76, the base material 3 is placed. As the substrate 3, a glass substrate having a flat surface was used.

  The water vapor B containing the catalyst was supplied to the base material 3 in the film forming apparatus 7 through the catalyst introduction pipe 74. The atmosphere in the film forming apparatus 7 was 100 RH humidity, 0.5 ppm hydrochloric acid, and a temperature of 25 ° C. Under this atmosphere, the raw material solution A prepared above was dropped. The dripping amount of the raw material solution A was about 2 ml. After stopping the dropping of the raw material solution A, the turntable 76 was rotated to rotate the base material 3. The rotation speed was 500 rpm. The rotation of the substrate 3 was maintained for 300 seconds. In the meantime, the raw material solution A spread on the base material 3 in the form of a thin film. The upper surface of the substrate 3 was covered with a thin film-like raw material solution A having a thickness of 20 μm. As shown in the upper diagram of FIG. 1, water vapor B in the atmosphere adhered to the surface of the thin film raw material solution A. Due to the heat of vaporization caused by volatilization of the raw material solution A, the temperature of the raw material solution A decreased. As shown in the middle diagram of FIG. 1, water vapor b condensed on the surface of the raw material solution A to form water droplets b. As shown in the lower diagram of FIG. 1, after the water droplet b is formed, the alkoxide in the raw material solution A undergoes a sol-gel reaction by the action of the catalyst in the water droplet, and the raw material solution A is gelated. An oxide film 1 made of was formed. On the surface of the oxide film 1, minute protrusions 2 were formed.

  The surface of the film was photographed with an electron micrograph and shown in FIG. As shown in FIG. 4, a large number of minute convex portions (white dot portions) were separately dispersed on the surface of the film. The size (diameter) of the minute protrusions was about 0.8 μm to 2 μm, and the pitch interval of the minute protrusions was about 1 μm. The aspect ratio of the minute protrusions (the ratio of the height to the pitch interval of the minute protrusions) was 0.2. The thickness of the oxide film in the portion where the minute protrusions were not formed was 2 μm.

(Example 2)
In Example 2, an oxide film was produced by the following method.

  Dichloropentafluoropropane as a hydrophobic solvent in a container, polymethyl methacrylate resin (PMMA resin) 0.01 mol / L as an amphiphilic substance, and tetraethyl orthosilicate (TEOS) 0.3 as a silicon alkoxide A raw material solution A containing 0.1 mol / L of mol / L and triethoxy 1H, 1H, 2H, 2H-tridecafluorooctylsilane (TETTS) was prepared.

  As shown in FIGS. 2 and 3, a humidifier 5, an absorber 6, and a film forming apparatus 7 similar to those in Example 1 were prepared. In the humidifier 5, a carrier gas having a flow rate of 500 cc / min was introduced into the humidifier 5, and moisture was included in the carrier gas to generate water vapor B. The produced water vapor B was led to the absorber 6 where the catalyst was included. In this example, ammonia was used as the catalyst. The water vapor B containing the catalyst was led to the film forming apparatus 7. In the film forming apparatus 7, the water vapor B is supplied to the internal space 70 of the container 71 through the catalyst introduction pipe 74 of the film forming apparatus 7. The atmosphere in the film forming apparatus 7 was humidity 100 RH%, ammonia 0.5 ppm, and temperature 25 ° C. Under this atmosphere, the raw material solution A prepared above was dropped. The dripping amount of the raw material solution A was about 2 ml.

  After stopping the dropping of the raw material solution A, the turntable 76 was rotated to rotate the base material 3. The rotation speed was 1500 rpm. The rotation of the substrate 3 was maintained for 300 seconds. Meanwhile, the upper surface of the substrate 3 was covered with a thin film-like raw material solution A having a thickness of 10 μm. In the same manner as in Example 1, water droplets were formed on the surface of the raw material solution A. After the water droplets were formed, starting from the water droplets, the alkoxide in the raw material solution A caused a sol-gel reaction by the action of the catalyst in the water droplets, the raw material solution A gelled, and an oxide film made of silica was formed. Minute convex portions were formed on the surface of the oxide film. The surface of the oxide film was washed with acetone to remove resin components contained on the film surface and inside.

  The surface of the oxide film was photographed with an electron micrograph. As shown in FIG. 5, a large number of minute convex portions were dispersed and formed independently on the coating surface. The size (diameter) of the minute projections was about 0.8 μm, and the pitch interval between the minute projections was about 3 μm. The aspect ratio of the minute protrusions (the ratio of the height to the pitch interval of the minute protrusions) was 0.1. The thickness of the oxide film in the portion where the minute protrusions were not formed was 1 μm.

(Comparative Examples 1 and 2)
In Comparative Examples 1 and 2, immediately before supplying the raw material solution A onto the base material 3, the raw material solution A was mixed with hydrochloric acid as a catalyst. In Comparative Examples 1 and 2, the raw material solution A before adding hydrochloric acid has the same composition as in Examples 1 and 2, respectively. The concentration of hydrochloric acid in the raw material solution was 0.1 mol / L. Immediately after that, the raw material solution A containing hydrochloric acid was supplied onto the base material 3 from the raw material introduction tube 73 and the base material 3 was rotated to obtain an oxide film made of silica having a thickness of 0.5 μm. According to observation with an electron micrograph, the surfaces of the silica coatings of Comparative Examples 1 and 2 were smooth, and no minute protrusions were observed.

<Water repellency test>
A water repellency test was performed on the films of Examples 1 and 2 and Comparative Examples 1 and 2. The method of the water repellency test is based on JIS R 3257. The test results are shown in Table 1. The contact angle in Table 1 is an angle formed by the surface direction of the oxide film surface and water droplets.
As shown in Table 1, the oxide film of Example 1 had a small contact angle and was hydrophilic. The contact angle of Example 1 was smaller than that of Comparative Example 1, and the coating surface was found to be more hydrophilic than Comparative Example 1. The oxide films of Example 2 and Comparative Example 2 had a relatively large contact angle and water repellency. The oxide film of Example 2 had a higher contact angle and higher water repellency than Comparative Example 2.

1: oxide film, 2: minute convex part, 3: base material, 5: humidifier, 6: absorber, 7: film forming apparatus, A: raw material solution, B: water vapor, b: water droplet.

Claims (9)

A method for producing an oxide film formed from a raw material solution containing an alkoxide,
By forming water droplets composed of a catalyst and water on the surface of the raw material solution supplied in a thin film form on the base material, the sol-gel reaction of the alkoxide proceeds from the water droplets as a starting point, and the water droplets are minutely present. Forming the protrusion and forming the oxide film made of an inorganic oxide polymer;
The said raw material solution is a solution with low affinity with the said water droplet, Comprising: The manufacturing method of an oxide membrane | film | coat which has the said alkoxide, a hydrophobic solvent, and an amphiphile. The amphiphilic substance is a block copolymer of polyethylene glycol and polypropylene glycol, lecithin, or polymethyl methacrylate,
The manufacturing method of the oxide film of Claim 1 whose density | concentration of the said amphiphile is 0.01 mol / L or more and 0.3 mol / L or less.   3. The method for producing an oxide film according to claim 1, wherein the surface of the oxide film is washed with a solvent and the amphiphilic substance is removed after the minute projections are formed.   The method for producing an oxide film according to claim 1, wherein a specific gravity of the hydrophobic solvent is larger than a specific gravity of the water. The method for producing an oxide film according to any one of claims 1 to 4 , wherein the water droplets containing the catalyst are formed by condensing the water vapor by temperature change in an atmosphere in which the catalyst and water vapor are present. . In the cooling portion of the raw material solution is cooled by evaporation of the hydrophobic solvent, wherein the water vapor is condensed, according to any one of claims 1 to 5, wherein the water droplet is formed on the surface of the raw material solution Manufacturing method of oxide film. The said catalyst consists of a gaseous acid or an alkali, The manufacturing method of the oxide membrane | film | coat of any one of Claims 1-6 . The alkoxide, method of manufacturing an oxide film according to any one of claims 1 to 7, which is a metal alkoxide. The metal alkoxide includes at least one selected from the group consisting of Si alkoxide, Ti alkoxide, U alkoxide, Tn alkoxide, Zr alkoxide, Ce alkoxide, Sn alkoxide, Cu alkoxide, Sn alkoxide, Zn alkoxide, Al alkoxide, and Sc alkoxide. The manufacturing method of the oxide film of Claim 8 .