JP2002285357A - Stain resistant aluminum material and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stain resistant aluminum material which contains titanium dioxide exhibiting high photocatalytic activity, and having excellent surface smoothness as a surface layer, and a production method therefor. SOLUTION: The stain resistant aluminum material is obtained by coating the surface of an aluminum substrate having a nonporous film on the surface with a titanium dioxide precursory solution, and performing heat treatment thereto to deposit a titanium dioxide thin film thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an antifouling aluminum material having photocatalytic activity and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, research on hydrophilic, antibacterial, and antifouling coatings has been attracting attention for outdoor installations such as buildings and indoor structures and facilities of buildings. Antibacterial and antifouling coating
There is a long-awaited desire to not only maintain the aesthetic appearance of the building for a long period of time, but also prevent hospital-acquired infections in hospitals and maintain a clean indoor environment.

[0003] Titanium dioxide is a new material that is attracting attention for its photocatalytic function and is expected to be developed as an environmental material, and various production methods have been proposed. Conventionally, a method has been reported in which anatase particles having photocatalytic activity are calcined, mixed with a binder, and applied to a metal surface (Takeuchi et al .: World of Photocatalyst, Industrial Research Council (1999) p.44) and thin film production by CVD. ing. Further, the metal alkoxide is dissolved in an appropriate solvent such as an alcohol, and the solution is hydrolyzed and polycondensed to prepare a polymer sol (colloidal dispersion).
A sol (solution) that is applied on a substrate, dried and crystallized by heat treatment
-The gel (solid) method is known. In this method, it is difficult to store the dispersion in the sol state in a constant state for a long period of time, and since the dispersion in the sol state gels in a solution and deposits on the substrate to form a film, unreacted substances Also, there was a problem that the sol solution used once could not be used again because it became a gel.

[0004] A report of direct coating on a glass surface by a liquid phase method and baking (Rikkenji et al .: Abstracts of the 67th Spring Meeting of the Electrochemical Society of Japan, p. 132) discloses conductive glass as a photocatalytic activity of a TiO ₂ thin film. And non-conductive glass, T
The photocatalysis when iO ₂ is coated is being studied. Although the conductive glass was expected to increase the photocatalytic activity, the results were different from the predictions and stated that further research is needed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antifouling aluminum material having titanium dioxide having high photocatalytic activity as a surface layer and a method for producing the same. Another object of the present invention is to provide a photocatalyst-supporting aluminum material having titanium dioxide having excellent surface smoothness as a surface layer.

[0006]

That is, the present invention provides an antifouling aluminum material having a titanium dioxide thin film formed by applying a titanium dioxide precursor solution on an aluminum substrate having a nonporous film on its surface and subjecting it to a heat treatment. provide. Here, the geometric film thickness of the nonporous film is 10 to 2000 nm, and the geometric film thickness of the titanium dioxide thin film is 5 to 1 nm.
It is preferably 000 nm. The antifouling referred to here is the decomposition of organic pollutants attached to the aluminum material,
The cleaning function is due to a redox action and a hydrophilic action caused by photocatalytic activity which are developed by irradiating the titanium dioxide thin film formed on the aluminum material surface with ultraviolet rays.

Further, the aluminum substrate is integrally formed on a surface of a material other than aluminum, or the titanium dioxide precursor solution contains a pigment,
Alternatively, the aluminum substrate may be colored. Further, the present invention provides a method for producing an antifouling aluminum material in which a titanium dioxide precursor solution is applied on an aluminum substrate having a nonporous film on its surface and heat-treated to form a titanium dioxide thin film.

[0008] Here, the nonporous film is obtained by a process of immersing an aluminum oxide film or an aluminum substrate in a chemical conversion solution generated by heat treatment, or obtained by anodizing, or by electropolishing. It may be obtained by a treatment or a treatment obtained by immersing an aluminum substrate in an inorganic chemical solution. Further, a production method wherein the titanium dioxide precursor solution contains a pigment,
Alternatively, the heat treatment may be performed at 300 to 500 ° C. for 30 minutes to 5 hours.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antifouling aluminum material having a titanium dioxide thin film on an aluminum substrate having a nonporous film on its surface. It is preferably formed by applying a titanium dioxide precursor solution prepared from a titanium compound having a property and an aromatic compound solution, followed by heat treatment. The formed titanium dioxide thin film shows high photocatalytic activity. In addition, a titanium dioxide thin film having excellent surface smoothness can be formed.

The aluminum or aluminum alloy (hereinafter sometimes collectively referred to as aluminum) used in the present invention is not particularly limited, and may be any. For Japanese Industrial Standard products, JIS A 1000s, 2000s, 3000s, 4000s, 50s
Examples are 00s, 6000s and 7000s, which are active metals, but are approximately 0.
Amorphous alumina which is a transparent natural oxide film having a thickness of about 01 μm is formed. The non-porous film of the present invention is formed on the underlying aluminum surface excluding the oxide film,
An ordinary anodic oxide film has pores and high hydrophilicity, whereas an oxide film is not amorphous aluminum oxide but nonporous and has low hydrophilicity. The conditions for forming the nonporous film are as follows. For an oxide film obtained by electrolytic treatment, a nonporous aluminum oxide film is obtained by anodizing or electrolytic polishing in an electrolyte solution for forming a nonporous aluminum oxide film. In a nonporous aluminum oxide film obtained by a chemical conversion treatment, a thin compound film is formed on the surface by utilizing a chemical reaction between aluminum and a processing solution. There are chromate treatment and phosphate treatment for forming a corrosion-resistant inorganic salt film, and boehmite treatment for forming an inert aluminum oxide film. Among the nonporous films obtained by heat treatment, there is an aluminum oxide film formed by heat treatment such as annealing or homogenization of an aluminum material.

The non-porous film can be obtained by subjecting an aluminum material to a degreasing treatment or the like. The non-porous film may be obtained by performing the following treatment, or may be obtained by combining a plurality of the following treatments. May be used. 1) Aluminum oxide film formed by heat treatment Heat treatment such as annealing of an aluminum material after rolling or homogenization after extrusion molding is exemplified. The heat treatment conditions for obtaining a more stable non-porous aluminum oxide film include, for example, 500 ° C., 40-60 n in dry air.
The conditions for obtaining the oxide film of m are mentioned. The composition of the oxide film is η-Al ₂ O ₃ or γ-Al ₂ O ₃ .

2) When a coated aluminum material obtained by immersing an aluminum substrate in a chemical conversion solution is put into hot water or steam, a process such as 2Al + 4H ₂ O = Al ₂ O ₃ .1H ₂ O (boehmite) + 3H ₂ To form a nonporous aluminum oxide film. Since this film is non-porous, film formation does not proceed further. Therefore, before the porous material is anodized and chemically converted by a known method to form a porous aluminum oxide film on the aluminum substrate, the aluminum material is placed in hot water or steam. The surface portion can be made nonporous.

Specifically, an aluminum material is immersed in a chemical conversion aqueous solution. For example, it is immersed in a 0.1 to 0.5% aqueous ammonia solution at a temperature of 90 ° C. or higher for 10 to 30 minutes. Then, by boiling in a 0.5% triethanolamine aqueous solution or boiling in water, a non-porous film of 200 to 1000 nm is obtained.

3) Nonporous aluminum oxide film obtained by anodizing treatment An aluminum material is subjected to anodizing treatment in a nonporous oxide film forming electrolyte solution. This is different from normal anodization,
Anodize under conditions that do not form a porous layer. For example, anodizing is performed at 10 to 100 V in an aqueous solution of boric acid, ammonium borate, ammonium tartrate, or the like. The boric acid solution may have a concentration of 30%, 25 ° C., 30 V, and 5 minutes. The thickness of the obtained nonporous aluminum oxide film is proportional to the formation voltage and is about 10 nm / V.

4) Coating Obtained by Electropolishing The aluminum material is used as an anode and subjected to direct current electrolysis in a phosphoric acid-butyl alcohol solution, a perchloric acid-ethyl alcohol solution, a phosphoric acid aqueous solution or the like. At this time, an anodic oxide film is formed on the surface. By adjusting the dissolving power of the electropolishing liquid and the film formation rate in balance, the surface becomes smooth and a nonporous aluminum oxide film of 100 to 200 nm is formed. Is done. 5) Coating obtained by dipping aluminum substrate in inorganic chemical solution An example is given in which an aluminum material is dipped in an aqueous solution mainly containing chromate, phosphate, sodium carbonate and the like. A very thin aluminum oxide film is formed at the aluminum interface, and a non-porous compound film composed of an inorganic chlorinated liquid composition is obtained on the very thin aluminum oxide film.

The geometric thickness of the nonporous aluminum oxide film is preferably 10 to 2000 nm. 10n
If it is less than m, the non-porous film is too thin and the effect of the invention is not obtained. 2
When the thickness is more than 000 nm, there are disadvantages such as cracking of the nonporous film and insufficient adhesion of the titanium dioxide thin film due to the influence of heat treatment at the time of forming the titanium dioxide thin film.

The antifouling aluminum material of the present invention has a high photocatalytic function since a titanium dioxide thin film is formed on an aluminum substrate having a nonporous aluminum oxide film.

The solution prepared from the hydrolyzable titanium compound and the aromatic solution is not a sol obtained by a conventional method, that is, an agglomerate of fine hydrated titanium oxide units, but an aromatic compound solvent. The aromatic ring of the nucleus,
This is a polymeric titanium dioxide precursor solution having a planar structure in which dehydration condensation of titanium hydroxide has progressed with reference to the surface of the aromatic ring. In other words, since it is devised to maintain the solution state immediately before it becomes a sol solution, it has an excellent feature that a coating film with good adhesion can be easily formed by heat-treating a film obtained by pulling up from the solution state. , A unique technique. It has been reported that the photocatalytic properties of titanium dioxide films on various ceramic substrates manufactured by this method are excellent, but the photocatalytic function is very much governed by the type of ceramic substrate, and in extreme cases the function is poor. Was not found to be expressed in some cases.

One example of a method for preparing a titanium dioxide precursor solution used in the present invention is described below. The solution used in the present invention is, for example, a titanium alkoxide is dissolved in an amount of 0.03 to 1.5 mol per 1 L of an aromatic compound solvent,
Then, at a temperature of 0 to 6 ° C., a water-alcohol mixed solution containing 1 to 20 wt% of water is added in an amount of 0.5 to 2 mol of water per 1 mol of titanium alkoxide. It is prepared by hydrolysis and dehydration condensation at 60 ° C. under ultrasonic waves or under stirring. Preferably, a solution concentrated as a titanium ion to a concentration of 0.1 to 1 mol / L is used. The resulting solution is a polymeric titanium dioxide precursor solution having a planar structure in which the aromatic ring of the aromatic compound solvent is used as a nucleus and the dehydration condensation of titanium hydroxide proceeds with reference to the surface of the aromatic ring.

The alkoxy group of the titanium alkoxide has 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms. Examples include ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, sec-butoxy, tert-butoxy, n-pentoxy and the like.

The solvent for dissolving the titanium alkoxide is
It is an aromatic compound solvent, and one kind or two or more kinds are used. Examples include benzene, aniline, toluene, xylene, ethylbenzene and the like. Particularly in the case of using benzene, easily trimer of titanium alkoxide is formed, it can control the structure of the reaction product.

The alcohol in the water-alcohol mixed solution added to the aromatic compound solvent in which the titanium alkoxide is dissolved is for adjusting the activity of water, that is, for suppressing hydrolysis and causing a slow reaction. . For this reason, the mixing ratio of the water-alcohol mixed solution, the rate of addition, and the temperature at the time of addition are also important for the reaction control, and it is necessary to make the reaction as slow as possible in the initial stage. If the reaction proceeds rapidly, an aggregate of fine titanium dioxide particles is formed, which is not preferable.

The alcohol used in the present invention is an alcohol having 1 to 10 carbon atoms, preferably an alcohol having 1 to 1 carbon atoms.
0 is a monohydric alcohol. One or more of these are used. As an example, ethyl alcohol, n-
Propyl alcohol, iso-propyl alcohol, n-
Butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, nonyl alcohol, n-decyl alcohol, etc. can give.

The water-alcohol mixed solution used in the present invention has a water content of 1 to 20% by weight, and the water-alcohol mixed solution added to the aromatic compound solvent in which the titanium alkoxide is dissolved is: Titanium alkoxide 1
It is the amount of water is 0.5 to 2 mole based on the mole.

When the content of water in the water-alcohol mixed solution is less than 1% by weight, the reaction rate is too slow to be practical. If it exceeds 20% by weight, the hydrolysis reaction proceeds rapidly, which is not preferable.

When the water-alcohol mixed solution added to the aromatic compound solvent in which the titanium alkoxide is dissolved contains less than 0.5 mol of water per 1 mol of titanium alkoxide, unreacted substances increase, which is not preferable. On the other hand, if it exceeds 2 mol, the reaction proceeds undesirably rapidly.

The temperature at which the water-alcohol mixed solution is added to the aromatic compound solvent in which the titanium alkoxide is dissolved is preferably 0 to 6 ° C. from the viewpoint of reaction control. Next, a water-alcohol mixed solution was added to the aromatic compound solvent in which the titanium alkoxide was dissolved,
The solution used in the present invention is obtained by hydrolysis and dehydration-condensation at 0 ° C. under ultrasonic waves or under stirring. When the temperature at the time of hydrolysis and dehydration condensation exceeds 60 ° C., the reaction is too fast, and when it is less than 0 ° C., the reaction is undesirably too slow.

The titanium dioxide precursor solution used in the present invention may contain a pigment. The precursor solution containing the pigment is applied to an aluminum substrate, and the aluminum alloy is coated with an antifouling aluminum film having a titanium dioxide thin film obtained by heat treatment. The material has excellent design properties in addition to antibacterial properties and antifouling properties. Pigments used are not particularly limited and exemplified in JIS K 5101 and the like,
Any of zinc white, titanium oxide, alumina, red iron, cadmium red, graphite, zinc yellow, chrome green, cobalt blue, manganese purple, carbon black and the like may be used. The preferred particle size of the pigment particles is from 3 to 500 nm.

The solution used in the present invention is a polymerized titanium dioxide having a planar structure in which an aromatic ring in an aromatic compound solvent is used as a nucleus and the dehydration condensation of titanium hydroxide proceeds with reference to the surface of the aromatic ring. It is not a colloidal solution of particulate titanium hydrated oxide obtained by a conventional sol-gel method.

Next, a solution prepared preferably at a concentration of 0.1 to 1 mol / L as titanium ions is applied by brush coating, spray coating, immersion, spin coating, flow coating or the like in a low humidity atmosphere. , Temperature 120-2
Dry at 50 ° C. Then, after drying, the temperature is 300 ~
A heat treatment is performed at 500 ° C. for 30 minutes to 5 hours, and the mixture is naturally cooled to room temperature. The titanium dioxide thin film on the aluminum material is preferably treated under a heating condition of a temperature lower than ± 100 ° C. for forming a boundary region between the region having the anatase structure and the amorphous region because the photocatalytic activity is high.

The thickness of the titanium dioxide thin film in the present invention is preferably a geometric thickness of 5 to 1000 nm. If it is less than this range, the photocatalytic effect cannot be sufficiently exhibited, and if it exceeds this range, it is not economical. The more preferable range can be freely determined according to the purpose, use, and the like of the support. Especially 10 to 500, more preferably 10 to 100 n
m.

The photocatalytic activity of titanium dioxide can be evaluated, for example, by the method described in Examples, and the aluminum material of the present invention is excellent in photocatalytic activity.

In the present invention, if the substrate on which the thin film is formed is aluminum or an aluminum alloy, the material,
The surface shape, structure, and the like are not particularly limited.

The surface shape of the substrate is not limited to a planar shape such as a plate-like material, but may be a three-dimensional shape. Although the solution used in the present invention is applied in a liquid form, even in a shape having irregularities, the difference in film thickness between the concave portion and the convex portion is excellent in step coverage, so that aluminum having a complicated surface shape is used. A thin film having excellent shape followability can be formed on the material.

The aluminum substrate used in the present invention may be, for example, a composite material with another metal, resin, glass, or the like, and may have an integral aluminum substrate having a nonporous aluminum oxide film on the surface. For example, an aluminum film may be provided on the surface by sputtering, welding, plating, or the like.

The aluminum substrate of the present invention may be a colored aluminum substrate as long as it has a nonporous film. The aluminum substrate can be added with various chemicals during the non-porous aluminum oxide coating treatment or in the case of independent surface treatment, and can be made to have various hues by etching or soaking. Grey, black, brown,
It is known in the literature to color yellow, red, blue and others. If a colored aluminum substrate is used and a pigment is further added to the titanium dioxide precursor solution, finer adjustment of the color tone is possible. The antifouling aluminum material of the present invention using a colored aluminum substrate can impart design properties as well as antibacterial properties and antifouling properties.

Further, between the aluminum material and the surface layer,
It may be a multilayer film having one or more functional films. Examples of the functional thin film include functional thin films of metals, alloys, oxides, nitrides, and carbides thereof.

The use of the antifouling aluminum material of the present invention is not particularly limited, but the antifouling property, antifouling property and abrasion resistance attributed to the high photocatalytic activity exhibited by the titanium dioxide film can be used, for example, in high-rise buildings. Curtain wall materials, sashes for buildings and houses, exterior products such as balconies and balconies, equipment such as beds and operating tables for hospitals and clinics, bathtubs, kitchen sinks, washbasins, toilet bowls, bridges and bridges
Various parts for building decoration, outdoor and indoor sculptures, outdoor and indoor decorations, mirror frames, and the like can be given.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Heating conditions and photocatalytic activity The aluminum plate used was 99.99% pure. The ingot was cut to a thickness of 10 mm, and then cold-rolled to a thickness of 2 mm to obtain 40 × 7.
The plate was finished to a size of 0 × 2 mm and annealed at 300 ° C. for 1 hour. By the above treatment, a nonporous aluminum oxide film is formed on the surface of the aluminum plate.

<Preparation of Titanium Dioxide Precursor Solution> A metal salt, titanium-n, was added to benzene, an aromatic compound solvent.
After dissolving 0.5 mol / L of butoxide and refluxing for 10 hours, a water-butanol solution containing 5 wt% of water at a temperature of 6 ° C. is adjusted to 0.5 mol of water with respect to 1 mol of titanium-n-butoxide. Then, the mixture was heated at 60 ° C. for 10 hours, and the solution subjected to hydrolysis and dehydration condensation under stirring and standing was concentrated by an evaporator so as to have a concentration of 1 mol / L as titanium ions, and the concentration was adjusted. The prepared solution was stable after one year if stored in a cool and dark place.

Using this titanium dioxide solution, an aluminum plate was pulled up from the titanium dioxide solution at a constant speed and applied by a lifting device using a stepping motor. The pulling speed was changed to 0.408 mm / s at the maximum based on 0.165 mm / s. The sample to which the titanium dioxide solution was applied mainly changed the heat treatment time from 30 minutes to 1 hour, held it, and then cooled the furnace.

2. Measurement of Photocatalytic Activity The heat-treated sample was a photocatalytic checker PC manufactured by Vacuum Riko.
In order to confirm whether or not there is a photocatalytic function using C-1, methylene blue was applied to the surface, and the wavelength was 650 nm.
The sample was irradiated with ultraviolet light using a light source fixed to the sample, and the amount of change in absorbance that changed with time was measured. In addition, in order to see the crystalline titanium dioxide, Shimadzu XRD
A -6000 thin-film X-ray measuring apparatus was used. The surface morphology of the sample was measured using a Hitachi scanning electron microscope (SEM) S-350.
Observed using 0H. The results were compared as a graph in which the horizontal axis represents ultraviolet irradiation time, and the vertical axis represents the amount of methylene blue used to decompose by the photocatalytic function due to ultraviolet irradiation (hereinafter referred to as absorbance change). The fact that the change in absorbance starts to increase with the elapse of the ultraviolet irradiation time indicates that methylene blue has started to decompose, and means that the larger the change in absorbance, the greater the amount of methylene blue decomposed. In addition, the larger the amount of change in absorbance at the initial stage of irradiation, the faster the photocatalytic function functions. Therefore, the initial change is particularly noted.

3. Experimental Results and Discussion <Experiment 1> FIG. 1 shows the results of examining the photocatalytic function of an aluminum material with a different heat treatment temperature. The graph shows the results of applying a titanium dioxide precursor solution to a pure aluminum material at a pulling rate of 0.165 mm / s and then performing a heat treatment at each temperature for 1 hour. Heat treatment temperature is 250 ° C (52
At the lowest temperature of 3K), the change in absorbance hardly increases at the beginning of the irradiation, but it increases slightly with time. When the heat treatment temperature was increased to 350 ° C. (623 K), the amount of change in absorbance increased at any irradiation time,
It can be seen that the temperature becomes extremely large when the temperature is increased to 0 ° C. (673 K). However, the heat treatment temperature was further increased by 50 ° C.
When the temperature was 450 ° C. (723 K), the amount of change in absorbance was smaller than the value at 400 ° C., and there was a tendency that the photocatalytic function was reduced. Further raise the temperature to 500 ° C (7
73K), the change in absorbance becomes smaller and 5
When the irradiation time is up to 0.3 minutes, the change in absorbance is almost the same as that at 350 ° C., and is 15 minutes (0.
In the irradiation after 9 ks), the amount of change in the absorbance hardly changes over time.

<Experiment 2> FIG. 2 shows the results of confirming how the photocatalytic function changes depending on the surface properties of the aluminum base material sample. After annealing, in order to remove the aluminum oxide film, the titanium dioxide film formed on the aluminum surface that has been washed with aqua regia, the change in the absorbance starts to increase after 1 minute (0.06 ks) of ultraviolet irradiation, and the photocatalytic function You can see that started working. The amount of change in absorbance increases as the irradiation time increases, but the amount of change in absorbance decreases after 7 minutes (0.42 ks) and tends to increase gradually. On the other hand, the sample surface was buffed and 1
Initially 10.6 for a sample polished with 500 emery paper
In the case of irradiation with aqua regia, there is a tendency that the change in absorbance does not become so large when irradiation is performed up to a minute (0.64 ks). Tend to be slightly higher. It is considered that the photocatalytic function changes depending on the effective area where the titanium dioxide film comes into contact with methylene blue. If the surface of the sample has irregularities, it is presumed that the photocatalytic function becomes high because the contact area increases. However, since the buffing abrasive and the emery polishing change in shape due to mechanical polishing, it is considered that there is a slight difference in surface morphology, but it is considered that such a change in unevenness does not significantly affect the photocatalytic function. In contrast, when the sample surface was mirror-finished by electropolishing to form a nonporous film, 2 minutes (0.12
ks), the amount of change in absorbance increases, and gradually increases with time, but 30 minutes (1.8 ks).
The subsequent change in absorbance is also large. The sample having the largest change in absorbance was a sample (heat treatment (non-porous film + TiO ₂ )) in which an aluminum oxide film was formed on the surface after rolling and heat treatment at 300 ° C. for 60 minutes. As a comparison, a result of applying methylene blue to a sample (untreated), which is an aluminum sample subjected to electrolytic polishing and not coated with a titanium dioxide film, and irradiating the sample with ultraviolet light is shown. Even after the elapse of the ultraviolet irradiation time, the amount of change in absorbance did not increase, and it was confirmed that the photocatalytic function was not exhibited.

Next, FIGS. 3 and 4 show changes in the photocatalytic function depending on the surface state of the titanium dioxide film. 35
The sample subjected to the heat treatment at 0 ° C. for 1 hour (3.6 ks) has a photocatalytic function, but traces of a titanium dioxide film peeling off are seen everywhere on the surface as shown in FIG. The sample heat-treated at 400 ° C. for one hour exhibited the best photocatalytic function, and had a very smooth surface as shown in FIG. In addition, the sample heat-treated at 500 ° C. for 1 hour shown in FIG. 4 (a) has almost no photocatalytic function, and a portion that appears to have peeled off on the surface is confirmed to be linearly arranged on the entire surface of the sample. Was. In the sample in which such a good photocatalytic function is expressed, a smooth surface morphology is observed.

[0046]

The antifouling aluminum material of the present invention has high photocatalytic activity and excellent surface smoothness. Also,
When the titanium dioxide precursor solution contains a pigment or when a colored aluminum substrate is used, the design is more excellent.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in absorbance with respect to an ultraviolet irradiation time, which is a measurement result of a photocatalytic activity of a titanium dioxide thin film formed on pure aluminum by performing heat treatment for various times while changing a heating temperature.

FIG. 2 is a graph showing a change in absorbance with respect to an ultraviolet irradiation time, showing how a photocatalytic function changes depending on the surface morphology of an aluminum base material sample.

FIG. 3 (a) is an SEM micrograph of the surface of titanium dioxide on a pure aluminum plate obtained by heat treatment at 350 ° C. and (b) at 400 ° C. for 1 hour ((a)
It is a schematic diagram which shows (150 times, (b) 50 times).

FIG. 4 (a) is a schematic view showing a SEM micrograph (× 50) of the surface of titanium dioxide on a pure aluminum plate obtained by performing a heat treatment at a temperature of 500 ° C. for one hour.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C01G 23/053 C01G 23/053 (71) Applicant 000228349 Nippon Carlit Co., Ltd. 1 Kanda Izumicho, Chiyoda-ku, Tokyo (72) Inventor Seiichi Rengakuji 1-27-110, Awashimacho, Toyama City, Toyama F-term (reference) 4G047 CA02 CB05 CC03 CD02 4G069 AA01 AA03 AA08 BA01A BA01B BA04A BA04B BA48A CD10 DA06 EA08 EB15X EB15 ED02Y ED02Y FA01 FA03 FB23 FB29 FB39 FC07 4K044 AA06 AB02 AB03 AB04 AB05 AB06 BA02 BA12 BB03 BC02 CA02 CA04 CA53 CA62

Claims (6)

[Claims] An antifouling aluminum material comprising a titanium dioxide precursor solution applied to an aluminum substrate having a nonporous film on its surface and heat-treated to form a titanium dioxide thin film. 2. The antifouling aluminum material according to claim 1, wherein the non-porous film has a geometric thickness of 10 to 2000 nm. 3. The antifouling aluminum material according to claim 1, wherein the titanium dioxide thin film has a geometric thickness of 5 to 1000 nm. 4. A method for producing an antifouling aluminum material comprising forming a titanium dioxide thin film by applying a titanium dioxide precursor solution on an aluminum substrate having a nonporous film on its surface and subjecting it to a heat treatment. 5. The method according to claim 4, wherein the non-porous film is an aluminum oxide film formed by heat treatment. 6. The heat treatment is performed at 300 to 500 ° C.
The method according to any one of claims 4 to 5, wherein the heating is performed for 30 minutes to 5 hours.