JP3912976B2 - Method for producing titanium substrate having photocatalyst film and method for hydrophilizing titanium substrate surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for making the surface of a substance hydrophilic in a photocatalytic manner and a method for producing the same, and particularly to a technique applied when a substrate is made of a metal material.
[0002]
[Prior art]
Substances having a photocatalytic function on the surface of various substrates (for example, TiO₂) Is disclosed in Japanese Patent No. 2756474 and International Patent No. WO 97/23572. The materials of the base material disclosed here are various materials including glass, tile, plastic, and metal.
[0003]
With respect to a method for producing a substance having a photocatalytic function on the surface of the substrate when the substrate is a metal, a conventional production method will be described with reference to FIG.
(1) In the metal rolling / cutting step, the metal 5 serving as a base material is rolled to a predetermined size and cut out. (2) TiO₂In the film forming step, TiO having a photocatalytic function on the metal 5₂The film 2 is formed by some method. Finally, (3) in the annealing step, heat treatment is performed at a predetermined temperature in a predetermined atmosphere, for example, in the air.
[0004]
[Problems to be solved by the invention]
TiO on substrate₂In order to express or improve the performance as a photocatalyst, a heat treatment is required in the atmosphere. As the temperature of the heat treatment, a high temperature such as 500 to 800 ° C. is often required. However, in this heat treatment step, the component of the base material is TiO₂A new impurity phase is formed by diffusing into TiO₂This may cause a problem that the photocatalytic function is impaired as a result, or cannot be fully exhibited.
For example, when general soda glass is used as a substrate, TiO₂After coating with some method, when heat treatment is performed at a temperature of 500 ° C., sodium which is a component of soda glass is converted to TiO 2.₂It is said that it diffuses in and forms a complex oxide with Ti, impairing the photocatalytic function. When a metal is used as a base material, a specific report example is unknown, but the metal component is TiO.₂It is thought that the photocatalytic deterioration of function due to diffusion inside is unavoidable.
[0005]
In order to avoid this case, silica is first coated as an intermediate layer on soda glass, and TiO 2 is coated thereon.₂A method of coating is disclosed. Here silica (SiO₂) Function as a blocking layer to prevent sodium diffusion.
Although this avoidance measure seems to be widely applicable, I think it is not universal. For example, when considering an application for making the surface of a metal base material photocatalytically hydrophilic as an industrial application, it is generally said that a metal and ceramics or glass are difficult to stack. This is because there is a problem such as delamination that arises because the coefficients of thermal expansion and the like are greatly different.
[0006]
In the present invention, when the base material is a metal, the surface is made hydrophilic photocatalytically without deteriorating the mechanical strength such as peeling and without deteriorating the photocatalytic function due to diffusion of components from the base material during heat treatment. We will contribute to the industry by disclosing the method to make it easy and supplementing the part that could not be covered by the prior art.
[0007]
[Means for Solving the Problems]
  A photocatalyst comprising a rolling / cutting step of a metal substrate, a pickling treatment step of the obtained metal substrate, a film forming step of a photocatalytic substance on the metal substrate, and an annealing step after film formation Provided is a method for producing a metal substrate having a film.
  Moreover, the rolling / cutting-out process of a metal base material, the pickling process process of the obtained metal base material, and the TiO to the metal base material surface after that₂A method for hydrophilizing the surface of a metal substrate, including a film forming step, an annealing step after film formation, and a light irradiation step.
  In the present invention, a titanium substrate is used as the metal substrate, and titanium oxide is used as the photocatalytic substance.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
  Examples of metal substrates include titanium, stainless steel, aluminum, copper, or alloys.But,Metal substrate used in the present inventionIs titanium. For example, if the metal substrate is a thin plate, it satisfies the function of being able to be bent and used by being wound or stored, and titanium is excellent in toughness and heat resistance.
  One of the reasons why titanium is preferable is that the thermal expansion coefficient can be matched with that of titanium oxide. That is, in general, one of the causes of delamination in the joining of different materials is that the thermal expansion coefficients are different from each other, and tensile stress or compressive stress is generated during the thermal history. In order to avoid such a situation, a technique for matching the thermal expansion coefficients of dissimilar materials to be joined by some method is known. According to the scientific chronology, the thermal expansion coefficients of titanium, titanium oxide, iron, stainless steel, aluminum, and copper are 8.6 × 10 in order per 1 ° C.^-6, 9 × 10^-6, 11.8 × 10^-6, 14.7 × 10^-6, 23.1 × 10^-616.5 × 10^-6Thus, it can be seen that the thermal expansion coefficients of titanium and titanium oxide are almost the same, which is preferable as compared with other iron, stainless steel and the like. In the present invention, separation of titanium oxide is avoided by selecting titanium as the metal substrate.
[0009]
  A photocatalytic substance is one in which a reactant does not absorb light and the photocatalytic substance absorbs light in a phenomenon and causes a reaction by its energy.₂ZnO, SnO₂, SrTiO_Three, WO_Three, Bi₂O_Three, Fe₂O_ThreeEtc.,Photocatalytic substance used in the present inventionIs TiO₂It is. TiO₂Has a feature of catalyzing reactions such as water decomposition reaction and organic substance decomposition reaction, absorbing ultraviolet rays shorter than 400 nm, and hydrophilizing by absorbing light. Other examples of the photocatalyst capable of hydrophilizing the surface of the metal substrate include ZnO. In the present invention, a metal substrate and TiO on the metal substrate₂The TiO.₂By irradiating the film with light, a metal substrate having a hydrophilized surface having a contact angle with water of 10 ° or less can be provided.
[0010]
An example of a film formation flow based on the present invention is shown in FIG.
FIG. 1 shows (1) rolling and cutting of a titanium substrate 1, (2) pickling treatment using an acid 4, and (3) TiO.₂Each step of titanium oxide film forming the photocatalytic film 2 and (4) annealing is shown.
Titanium rolling / cutting is the same as in the prior art.
The present invention is characterized by a subsequent pickling treatment. The pickling treatment refers to removing the impurity layer on the metal surface (in FIG. 1, the titanium substrate 1) using the acid 4. An impurity layer composed of C (carbon) and titanium exists on the rolled titanium surface. The generation of this impurity layer is considered to be an unavoidable phenomenon in the manufacturing process of a general titanium plate material. In fact, when the rolled titanium plate material from different material manufacturers was analyzed, a similar impurity layer was obtained. Without removing this impurity layer, TiO₂When a film is formed and annealed, C (carbon) is converted to TiO.₂It diffuses in and causes photocatalytic performance degradation. Therefore, it is necessary to remove the impurity layer by pickling treatment.
The acid is not particularly limited and may be one generally used in the field of metal etching. For example, hydrochloric acid (1.5% by weight), nitric acid (2.5% by weight), hydrofluoric acid (1% by weight), water (95% by weight), nitric acid (2.5% by weight), fluorine Those having a composition of an acid (2.5% by weight) and water (95% by weight) can be mentioned.
[0011]
The effect of the pickling treatment depends on the treatment time and temperature of exposing the titanium substrate to acid. If the liquid temperature is raised, the etching rate increases, and if the processing time is extended, the etching depth increases. Suitable pickling treatment conditions may be determined as appropriate depending on what depth is desired to be etched. The standard of the thickness to be removed in that case can be determined by measuring the surface of the titanium base material by X-ray diffraction. That is, in the X-ray diffraction data, the diffraction thickness of the phase other than titanium as recognized in (a) of FIG.
[0012]
The film formation method of the photocatalytic substance is not particularly limited, and generally known methods such as a binder method, a sol-gel method, and a gas phase method can be used.
The film thickness of the photocatalytic substance is preferably 1 μm or less, more preferably 50 to 500 nm, and even more preferably 100 nm to 500 nm. TiO illustrated in FIG.₂The film thickness is preferably in the same range. Although it may be less than 50 nm in terms of hydrophilicity, the diffusion distance of electron / hole pairs is considered to be about 50 nm, and is preferably 50 nm or more, and more preferably 100 nm or more from the viewpoint of light utilization efficiency. The lower limit values of these film thicknesses are specifically TiO with film thicknesses of 50 nm, 100 nm, and 150 nm.₂This is based on the result of experimenting on the photocatalytic effect, here the effect of surface hydrophilization by UV irradiation. When the film thickness exceeds 1 μm, for example, TiO is used during annealing.₂Since there exists a possibility that a film | membrane may peel, it is preferably 1 μm or less, more preferably 500 nm or less. This is based on the experimental fact that peeling did not occur even when annealing at a maximum temperature of 1000 ° C. by setting the film thickness to 500 nm or less.
[0013]
Annealing is performed at a predetermined temperature for a predetermined time in an atmosphere in which oxygen is present and no reducing gas is present, for example, in the air.₂It refers to exposing a substrate on which a film is formed. There are two main purposes for annealing. One is TiO during film formation₂When the film is in a state of oxygen deficiency, the oxygen deficiency is eliminated by annealing. This is because this treatment improves the photocatalytic function. In this case, oxygen deficiency means that the composition ratio of Ti and O (oxygen) deviates from the stoichiometric ratio of 1: 2, and oxygen is deficient 1: (2-x). Point to. Here, x is a minute value. TiO₂As a method for investigating oxygen deficiency, a technique using Raman spectroscopy disclosed in the following paper can be used (JC Parker and RW Siegel, J. Mater. Res., Vol. .5, No. 6, pp 1246-1252, (1990)). This method uses anatase-structured TiO₂In the Raman spectrum, the Raman wave number is usually 144 cm¹Is based on the experimental result that the peak position shifts to the higher wavenumber side in response to the oxygen deficiency. TiO with anatase structure with oxygen deficiency₂It is reported that the position of the Raman peak is restored to the peak position of the bulk anatase by performing an appropriate heat treatment in the atmosphere. Based on the above report, in the present invention, TiO was prototyped by setting the annealing temperature conditions as untreated, 400 ° C., 500 ° C., and 600 ° C.₂By measuring the Raman spectrum of the membrane and comparing the position of the Raman peak with that of a commercially available powder reagent, anatase, we experimentally determine the effect of annealing, that is, whether oxygen deficiency has been eliminated, and appropriate annealing temperature conditions. . As a result, oxygen deficiency can be eliminated by annealing, and appropriate annealing conditions are based on experimental results of 400 ° C. or higher, more preferably 500 ° C. or higher.
The second is TiO during film formation.₂In the case where the film contains an amorphous phase, the transition from the amorphous phase to the crystalline phase is advanced by annealing to improve the photocatalytic function. It has been confirmed by an X-ray diffraction test that the above-mentioned transition has progressed by annealing. Here, the amorphous phase is also called an amorphous phase, and in the present invention, it refers to a phase that is not a crystalline phase. Also, the amorphous phase has a composition of TiO₂However, it is known that it does not have a photocatalytic function.
[0014]
As a preferred first aspect of the present invention, the pickling treatment step and TiO₂TiO during the film formation process₂A pretreatment step (thermal oxidation treatment) of the film formation step can be performed. As illustrated in FIG. 2, (1) rolling and cutting of the titanium substrate 1, (2) pickling treatment using the acid 4, (3) pretreatment for forming the titanium oxide layer 3, (4) TiO₂Steps of titanium oxide film formation for forming the photocatalyst film 2 and (5) annealing are shown.
This treatment refers to exposing the substrate to a predetermined temperature for a predetermined time in an atmosphere in which oxygen is present and no reducing gas is present, for example, in the air, and is generally referred to as a thermal oxidation treatment.
A suitable treatment temperature can be selected from 400 to 700 ° C., and a suitable treatment time can be selected from several minutes to several tens of hours. However, if the temperature exceeds 700 ° C., peeling of the titanium oxide layer tends to occur. This is considered to be a result of the film thickness becoming too thick. If the temperature is less than 400 ° C., the growth of the titanium oxide layer may be extremely slow. The most preferable temperature range is 500 to 600 ° C., and the treatment time is in the range of 1 hour to several tens of hours.
[0015]
When the titanium substrate is heat-treated at a predetermined temperature, a titanium oxide layer is formed, and its outermost surface is TiO.₂And its crystal form is rutile or anatase. Further, the titanium oxide layer is an inclined layer, and the stoichiometric ratio of Ti and O (oxygen) gradually changes from 1: 2 to 1: 0, that is, Ti itself in the depth direction. Go. It is a general fact that such a gradient layer is firmly bonded to the substrate. TiO on the outermost surface of this titanium oxide layer₂On top of TiO₂Forming a film is preferable in terms of bonding of materials. TiO₂In the annealing process after film formation, TiO₂This is because it is possible to prevent peeling of the film.
Furthermore, as an effect of the titanium oxide layer, TiO₂Rather than depositing the film on a titanium substrate, the outermost surface TiO of the titanium oxide layer₂The film is formed on the TiO 2 immediately after film formation.₂The crystallization rate of the film can be increased. Here, the crystallization rate is TiO₂This is the ratio of the crystal phase to the total of the crystal phase and the amorphous phase constituting the film. Also, the amorphous phase has a composition of TiO₂However, it is known that it does not have a photocatalytic function. Therefore, the higher crystallization rate as the second effect of the titanium oxide layer means that the photocatalytic function is improved.
[0016]
As a preferred second embodiment of the present invention, TiO₂Pretreatment process of film formation process (acid heat treatment) pickling process and TiO₂An intermediate layer film forming step can be performed between the film forming step and the film forming step. As an example, FIG. 3 shows (1) rolling and cutting of the titanium substrate 1, (2) pickling treatment using the acid 4, (3) pretreatment for forming the titanium oxide layer 3, and (4) intermediate layer film formation. (5) TiO₂Each step of titanium oxide film forming the photocatalyst film 7 and (6) annealing is shown.
In a preferred first aspect of the present invention, TiO₂TiO of photocatalytic film₂The crystal structure is mainly composed of rutile and amorphous. TiO with amorphous structure₂Has almost no photocatalytic activity, and in this case, TiO having a rutile structure₂The photocatalytic effect is manifested. However, TiO₂It is known that anatase has a higher photocatalytic effect than rutile. Therefore, in order to improve the performance of hydrophilizing the surface, anatase TiO₂It is necessary to realize. In the first preferred embodiment of the present invention, the reason why the rutile type is mainly produced is that the titanium oxide layer produced in the pretreatment step (3) has a rutile type structure. In the subsequent titanium oxide film-forming step (4), when the underlying titanium oxide layer has a rutile structure, the titanium oxide film is selectively produced only as a rutile structure and an anatase structure is formed. do not do. The titanium oxide layer mainly having a rutile structure means that titanium oxide having an anatase structure does not exist, or titanium oxide having an anatase structure is present but the titanium oxide having a rutile structure has an anatase structure It means more than that. The composition of the titanium oxide layer mainly having a rutile structure of the present invention is TiO₂Usually, rutile-type titanium oxide is 10 to 80% by weight, anatase-type titanium oxide is 1% by weight or less, although it depends on conditions such as substrate heating temperature during film formation, gas atmosphere, especially oxygen partial pressure, annealing heat treatment temperature, annealing time And 20 to 90% by weight of amorphous titanium oxide.
[0017]
In a preferred second aspect of the present invention, an anatase phase can be generated by newly introducing an intermediate layer and forming a titanium oxide film using the intermediate layer as a base. This is because the anatase phase with higher photocatalytic activity is generated in an environment that is not affected by the rutile phase of the base. Specifically, as the intermediate layer, for example, SiO₂Is formed by sputtering, and the SiO 2₂TiO containing anatase phase by depositing titanium oxide with the film as a base₂A photocatalytic film is realized. The composition of the titanium oxide layer containing the anatase phase of the present invention is TiO 2.₂Usually, rutile type titanium oxide 0 to 40% by weight, anatase type titanium oxide 0 to 40% by weight depending on conditions such as substrate heating temperature during film formation, gas atmosphere, particularly oxygen partial pressure, annealing heat treatment temperature, and heat treatment time. %, 20 to 100% by weight of amorphous titanium oxide. The conditions are optimized so that the composition is preferably 10 to 40% by weight of rutile type titanium oxide, 10 to 40% by weight of anatase type titanium oxide, and 20 to 80% by weight of amorphous titanium oxide.
[0018]
As the intermediate layer, SiO₂, Al₂O_Three, ZrO₂, GeO₂In view of the low raw material cost and the ease of film formation, it is preferable to use an oxide such as₂It is. Therefore, as an intermediate layer, SiO₂Although the case where is used will be described as an example, the same applies to other oxides.
SiO₂The film thickness is preferably 20 nm to 1 μm, more preferably 50 to 500 nm. If the film thickness is thick, SiO₂There is a risk of film peeling. There are three factors that determine the lower limit of the film thickness. One is TiO₂TiO formed on the intermediate layer during film formation₂However, it is necessary to have a thickness so as not to be affected by the rutile titanium oxide (titanium oxide layer) serving as a base for the intermediate layer. Second, TiO during annealing₂A thickness that can prevent the diffusion of impurities into the film is necessary. Thirdly, the intermediate layer does not have an island-like structure, and a thickness is required to form a uniform film that can completely cover the base. Of the above three conditions relating to the thickness, the largest thickness condition is the lower limit of the thickness required for the intermediate layer in this case. This condition is determined based on a specific prototype and an evaluation result of the photocatalytic effect. SiO₂The crystal structure is preferably amorphous.
[0019]
SiO₂Examples of the film formation method include vapor deposition methods such as vapor deposition, sputtering, CVD, and ion plating, or wet methods such as sol-gel methods. SiO₂The film quality is different. In particular, the vapor phase method is desirable for applications in which adhesion to the substrate is important, but the wet method is desirable if importance is attached to low cost.
TiO containing anatase phase following the intermediate layer deposition process₂For the titanium oxide film forming step and the annealing step for forming the photocatalyst film 7, the method described above is used.
[0020]
【Example】
referenceExample 1
(1) Titanium rolling and cutting
  Titanium was rolled to a thickness of 0.1 mm, and then cut to a size of 2 inches φ. The purity of titanium used was 3N (99.9% by weight or more). The crystal phase on the surface of the Ti substrate in this state was examined by X-ray diffraction measurement. The result is shown in FIG. In addition to titanium diffraction lines, Ti₈C_FiveDiffraction lines were observed. This Ti₈C_FiveIs an impurity phase. The cause of this phase is unknown.
[0021]
(2) Pickling treatment
The impurity phase present on the surface of the titanium substrate was removed by pickling treatment. The acid used had a composition of hydrochloric acid (1.5% by weight), nitric acid (2.5% by weight), hydrofluoric acid (1% by weight), and water (95% by weight). The pickling treatment was performed by exposing the titanium substrate to the liquid temperature under room temperature for several minutes. According to the X-ray diffraction measurement, the surface of the titanium base material was removed by several tens of μm. The result is shown in FIG. It can be seen that diffraction lines other than Ti are not recognized and the impurity phase detected in FIG. 4A is removed by the pickling treatment.
[0022]
(3) TiO₂Film formation
TiO₂The film was formed on a titanium substrate after pickling treatment. The film thickness is 200 nm. As a film forming method, a magnetron sputtering method, which is a kind of vapor phase method, was used. For the sputtering target, rutile TiO₂Pellets produced by sintering powder were used. As a film forming gas atmosphere, a gas component obtained by adding oxygen to argon was used. The other details were in accordance with the film forming conditions of a general sputtering method.
[0023]
(4) Annealing
  In an air atmosphere, using an electric furnace, TiO under conditions of a temperature of 500 ° C. and a treatment time of 4 hours.₂The titanium substrate on which the film was formed was annealed. The electric furnace used is general equipment.
  TiO produced by the above four processes₂The titanium substrate on which the film was formedreferenceIt will be called a sample of the manufacturing method of Example 1.
[0024]
Comparative Example 1
  Other than omitting the pickling process,referencePerformed as in Example 1. The obtained sample will be referred to as a conventional manufacturing method sample.
[0025]
referenceExample 2
  referenceIn the same manner as in Example 1, the titanium substrate was rolled and cut out and pickled. The obtained titanium base material is made of TiO₂The following pretreatment was performed before film formation. The pretreatment was performed in an air atmosphere using an electric furnace at a temperature of 600 ° C. and a treatment time of 10 hours. The electric furnace used was general equipment. The surface of the titanium base material after the pretreatment was analyzed by X-ray diffraction. The obtained X-ray diffraction data is shown in FIG. In addition to Ti diffraction lines, rutile TiO₂And weak anatase TiO₂The diffraction line is recognized. Therefore, the surface of the titanium base material after the pretreatment is almost rutile TiO.₂You can see that it is covered with.
  After pretreatment,referenceSimilar to Example 1, TiO₂Film formation and annealing were performed.
  TiO manufactured by the above process₂The titanium substrate on which the film was formedreferenceIt will be called a sample of the manufacturing method of Example 2.
[0026]
Example1
  referenceIn the same manner as in Example 2, the titanium base material was rolled and cut out, pickled, and pretreated. The obtained titanium base material is made of TiO₂Before the film formation, the next intermediate layer was formed. SiO₂Using a magnetron sputtering method, which is a kind of vapor phase method, as a film forming method on a titanium substrate after pre-treating the film, a SiO2 film having a thickness of 200 nm is used.₂A film was formed. Specifically, fused synthetic quartz was used as a sputtering target, a gas component in which oxygen was added to argon as a film forming gas atmosphere, and other details were in accordance with film forming conditions of a general sputtering method.
  After intermediate layer deposition,referenceSimilar to Example 1, TiO₂Film formation and annealing were performed.
  TiO manufactured by the above process₂Example of titanium substrate with film formed1It will be called a sample of the manufacturing method.
[0027]
  Example1It was confirmed by an X-ray diffraction test that an anatase phase was produced by the production method described above. The test results are shown in FIG. It can be seen that anatase and rutile phases are formed.
[0028]
Sample evaluation 1 (Transition of surface hydrophilization with UV irradiation)
  referenceExample 12 and Example 1In order to investigate the photocatalytic function of this sample, the transition of surface hydrophilization with UV irradiation was measured. The UV used in the experiment was a 500cm mercury xenon lamp (UI-502Q) as the light source, a 15cm long water filter (synthetic quartz window material, water using distilled water), 2.5mm thickness The main component of the spectrum was an emission line of mercury with a wavelength of 365 nm, which was transmitted through an ultraviolet transmission visible absorption filter (HOYA U-340). The UV intensity at the sample position is 3.7 mW / cm in terms of a wavelength of 365 nm.²The in-plane distribution of the irradiation intensity was an intensity fluctuation within 5% with respect to the effective area of the sample. In the experiment, first, the contact angle of the sample with water in the initial state was measured, then the sample was irradiated with UV for a predetermined time, and the contact angle was measured again. Again, the operation of irradiating the sample with UV and measuring the contact angle was repeated. Here, care was taken not to measure the contact angle twice in the same analysis region of the sample. This is because the dried portion of the water droplet is more unnecessarily contaminated. The measurement method of the contact angle was based on the “static drop method” defined in JIS R 3257 “Test method for wettability of substrate glass surface”.
[0029]
  The experimental results are shown in FIGS. Since the UV irradiation intensity is a constant value, (intensity W / cm²) X (time sec) calculation, irradiation UV energy (J / cm²) To obtain the horizontal axis of FIGS. The horizontal axis of FIG. 6 and FIG. 7 is the integrated irradiation UV energy amount. The vertical axis | shaft of FIG. 6 and FIG. 7 took the contact angle with water.
  In FIG.referenceExperimental results of the sample by the manufacturing method of Example 1,referenceThe experimental result of the sample by the manufacturing method of Example 2 and the experimental result of the sample by the conventional manufacturing method were plotted for comparison. In FIG.referenceExperimental results of the sample by the manufacturing method of Example 2 and Examples1The experimental result of the sample by the manufacturing method was plotted.
[0030]
  As is clear from FIG.referenceIt can be seen that the sample produced by the production method of Example 1 is hydrophilized with less irradiation UV energy and superior in photocatalytic performance as compared with the sample produced by the conventional production method. This indicates that the removal of the impurity phase by the pickling treatment is effective.
  In the conventional manufacturing method, from the titanium base material to TiO in the annealing process.₂Diffusion of impurity phase into the film occurs,A substance that impairs the photocatalytic function is TiO₂It is thought that the result produced in the film is reflected.
[0031]
  As is clear from FIG.referenceIt can be seen that the sample produced by the production method of Example 2 is also hydrophilized with less irradiation UV energy and superior in photocatalytic performance as compared with the sample produced by the conventional production method.
  further,referenceSamples from the production method of Example 2 arereferenceCompared to the sample produced by the production method of Example 1, it is hydrophilized with less irradiation UV energy, and the photocatalytic performance is most excellent. this is,referenceIt shows that the removal of the impurity phase by the pickling treatment described in Example 1 is effective, and the formation of the titanium oxide layer by the pretreatment is also effective.
  referenceExample 2 andreferenceThe difference in the manufacturing method of Example 1 is the presence or absence of pretreatment, that is, the presence or absence of a titanium oxide layer. In photocatalytic function,referenceSample from the manufacturing method of Example 2referenceThe reason why it is superior to Example 1 isreferenceIt is considered that Example 2 is due to a higher crystallization rate.
[0032]
  As is clear from FIG.1The sample by the manufacturing method ofreferenceCompared to the sample produced by the production method of Example 2, it can be seen that it is hydrophilized with less irradiation UV energy and has superior photocatalytic performance. This indicates that the production method of the present invention using an intermediate layer is effective. Both FIG. 6 and FIG. 7referencePlots according to the manufacturing method of Example 2 are shown, but these do not agree because the initial state of the sample surface before UV irradiation is different. FIG. 6 shows a state in which the adsorbed species in the atmosphere are adsorbed on the surface (dirt) and the contact angle is increased after being left in the atmosphere for a while (one week or more) in a state called natural dirt. FIG. 7 intentionally finishes a hydrophobic surface by binding monolayer organic molecules to the surface. That is, by controlling the degree of contamination, the initial load (type and amount of molecular species present on the surface) for each sample is made uniform, and the hydrophilic effect can be evaluated with higher accuracy.
[0033]
Sample evaluation 2 (pencil scratch test)
  Deposited TiO₂In order to investigate the mechanical strength of the film, a pencil scratch test frequently used in the technical field of photocatalytic film was conducted, and TiO₂The pencil hardness of the film was determined.
  The pencil scratch test was performed by a method based on JIS K 5400 (Paint General Test Method).
  referenceThe sample by the manufacturing method of Example 2 obtained a result of “9H or higher” in pencil hardness. This indicates that the film hardness was higher than the maximum hardness 9H covered by the pencil scratch test. TiO film formed by general sol-gel method₂When the pencil hardness of the film was measured, a result of H to 3H was obtained.
  Samples made by conventional manufacturing methodsreferenceThe sample by the manufacturing method of Example 1 had a pencil hardness of about 8H. Therefore,referenceThe sample by the production method of Example 2 is a strong TiO due to the presence of the titanium oxide layer.₂It can be said that the film is realized on the titanium substrate.
[0034]
【The invention's effect】
  FIG. 6, which is a result of examining the transition of surface hydrophilization by UV irradiation,referenceIn addition to the effective removal of the impurity phase by the pickling treatment described in Example 1,referenceThis shows that the formation of the titanium oxide layer by the pretreatment of Example 2 is also effective. In addition, in the conventional manufacturing method, in the annealing treatment, the titanium substrate is changed to TiO.₂Substances that cause diffusion of the impurity phase into the film and impair the photocatalytic function are TiO₂It is thought that the result produced in the film is reflected. Further, as shown in FIG. 7, an example in which an intermediate layer was formed1It can be seen that the sample produced by this method is hydrophilized with less irradiation UV energy and superior in photocatalytic performance as compared with the sample produced by the production method without forming the intermediate layer. This indicates that the production method of the present invention using an intermediate layer is effective.
  Moreover, as the result of pencil hardness shows, the combination of the removal of the impurity phase by the pickling treatment and the formation of the titanium oxide layer by the pretreatment is based on the presence of the titanium oxide layer formed by the pretreatment, and the strong TiO₂The film can be realized on a titanium substrate.
[Brief description of the drawings]
FIG. 1 is a film formation flow chart of the present invention showing steps of (1) rolling and cutting of titanium, (2) pickling treatment, (3) titanium oxide film formation, and (4) annealing.
FIG. 2 is a film formation flow chart of the present invention showing steps of (1) rolling and cutting of titanium, (2) pickling, (3) pretreatment, (4) titanium oxide film formation, and (5) annealing. It is.
FIG. 3 shows the steps of (1) rolling and cutting of titanium, (2) pickling treatment, (3) pretreatment, (4) intermediate layer deposition, (5) titanium oxide deposition, and (6) annealing. It is the film-forming flowchart of this invention shown.
FIG. 4 is a diagram showing X-ray diffraction data of a titanium substrate after each of (a) rolling treatment, (b) pickling treatment, and (c) pretreatment (thermal oxidation treatment).
FIG. 5 (a) Example1(B) It is a figure which shows the X-ray-diffraction data of a titanium substrate.
FIG. 6 of the present inventionreferenceExample 1,referenceExample 2 and TiO prototyped in the prior art₂It is a figure which shows transition of the surface hydrophilization accompanying UV irradiation of a photocatalyst film | membrane.
[Fig. 7] of the present invention.referenceExample 2 and Examples1TiO prototyped in₂It is a figure which shows transition of the surface hydrophilization accompanying UV irradiation of a photocatalyst film | membrane.
FIG. 8 is a conventional film formation flow chart showing steps of (1) rolling and cutting of titanium, (2) titanium oxide film formation, and (3) annealing.

Claims (2)

Rolling and cutting process of titanium substrate;
Pickling treatment step of the obtained titanium substrate;
A thermal oxidation treatment step of obtaining a titanium oxide layer by treating the titanium substrate after the pickling treatment at 400 to 700 ° C. in an atmosphere in which oxygen is present and no reducing gas is present;
An intermediate layer forming step of forming an intermediate layer selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ and GeO ₂ using a vapor phase method on the titanium oxide layer;
A film forming step of forming a titanium oxide layer containing titanium oxide having anatase structure as a photocatalytic substance on the intermediate layer using a gas phase method;
A method for producing a titanium substrate having a photocatalyst film, comprising: an annealing step of heating the substrate after the film formation in an atmosphere in which oxygen is present and no reducing gas is present. Rolling and cutting process of titanium substrate;
Pickling treatment step of the obtained titanium substrate;
A thermal oxidation treatment step of obtaining a titanium oxide layer by treating the titanium substrate after the pickling treatment at 400 to 700 ° C. in an atmosphere in which oxygen is present and no reducing gas is present;
An intermediate layer forming step of forming an intermediate layer selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ and GeO ₂ using a vapor phase method on the titanium oxide layer;
Forming a titanium oxide layer containing titanium oxide having anatase structure on the intermediate layer using a vapor phase method;
An annealing step of heating the substrate after the film formation in an atmosphere in which oxygen is present and no reducing gas is present;
A method for hydrophilizing a titanium substrate surface, comprising a light irradiation step of irradiating the titanium oxide layer after annealing.

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