WO2015022960A1 - 可視光応答形光触媒体及びその製造方法 - Google Patents
可視光応答形光触媒体及びその製造方法 Download PDFInfo
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- WO2015022960A1 WO2015022960A1 PCT/JP2014/071288 JP2014071288W WO2015022960A1 WO 2015022960 A1 WO2015022960 A1 WO 2015022960A1 JP 2014071288 W JP2014071288 W JP 2014071288W WO 2015022960 A1 WO2015022960 A1 WO 2015022960A1
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- visible light
- titanium
- responsive photocatalyst
- oxide film
- photocatalyst
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- 239000011941 photocatalyst Substances 0.000 title claims abstract description 100
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 171
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 98
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 86
- 239000010936 titanium Substances 0.000 claims abstract description 58
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 58
- 238000010438 heat treatment Methods 0.000 claims abstract description 50
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 37
- 239000011593 sulfur Substances 0.000 claims abstract description 37
- 239000004408 titanium dioxide Substances 0.000 claims abstract description 29
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 229910001069 Ti alloy Inorganic materials 0.000 claims abstract description 19
- 238000007743 anodising Methods 0.000 claims description 67
- 238000011282 treatment Methods 0.000 claims description 55
- 239000000463 material Substances 0.000 claims description 51
- 230000000844 anti-bacterial effect Effects 0.000 claims description 46
- 230000001699 photocatalysis Effects 0.000 claims description 41
- 239000011148 porous material Substances 0.000 claims description 33
- 239000000758 substrate Substances 0.000 claims description 29
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 19
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 18
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 18
- 238000012360 testing method Methods 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 6
- 239000012298 atmosphere Substances 0.000 claims description 5
- 238000004080 punching Methods 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 3
- 238000009941 weaving Methods 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 239000011248 coating agent Substances 0.000 abstract description 7
- 238000000576 coating method Methods 0.000 abstract description 7
- 230000003647 oxidation Effects 0.000 abstract description 7
- 238000007254 oxidation reaction Methods 0.000 abstract description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 42
- 230000004298 light response Effects 0.000 description 15
- 239000007864 aqueous solution Substances 0.000 description 12
- 238000002441 X-ray diffraction Methods 0.000 description 9
- 238000005238 degreasing Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 238000005554 pickling Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 238000001035 drying Methods 0.000 description 5
- 230000004043 responsiveness Effects 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000002048 anodisation reaction Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 230000001747 exhibiting effect Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- -1 titanium ions Chemical class 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- NHRVIENLFZAEPU-UHFFFAOYSA-J S(=S)(=O)([O-])[O-].[Ti+4].S(=S)(=O)([O-])[O-] Chemical compound S(=S)(=O)([O-])[O-].[Ti+4].S(=S)(=O)([O-])[O-] NHRVIENLFZAEPU-UHFFFAOYSA-J 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000003373 anti-fouling effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000004332 deodorization Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 235000007715 potassium iodide Nutrition 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical group OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
- B01J27/04—Sulfides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
- B01J21/063—Titanium; Oxides or hydroxides thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/39—Photocatalytic properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/64—Pore diameter
- B01J35/647—2-50 nm
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/348—Electrochemical processes, e.g. electrochemical deposition or anodisation
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/26—Anodisation of refractory metals or alloys based thereon
Definitions
- the present invention relates to a photocatalyst made of titanium or a titanium alloy and obtained by subjecting a thin base material to anodizing treatment and heat treatment, and particularly to a photocatalyst having photocatalytic activity for visible light and a method for producing the same. .
- a titanium oxide-containing solution in which a titanium oxide fine powder having photocatalytic activity is dissolved in a solvent is applied to the surface of the substrate to contain titanium oxide.
- a method (anodic oxidation type photocatalyst) for increasing the photocatalytic activity of the surface by heat treatment is performed.
- the above-mentioned paint type photocatalyst is widely put into practical use because it can exhibit photocatalytic activity easily and inexpensively on various base materials.
- a coating film having photocatalytic activity is formed on the base material, since the adhesion between the base material and the coating film is low, the lifetime in which the base material can exhibit photocatalytic activity is shortened. For this reason, in order to maintain photocatalytic activity on this substrate, there is a major problem that it is necessary to recoat a coating film having photocatalytic activity on this substrate.
- the fine powder having photocatalytic activity is dispersed in the solvent, the photocatalytic activity is hindered by the hardened solvent and the activity is lowered.
- the adhesion between the base material and the titanium oxide film exhibiting the photocatalytic activity is high, and the durability of the photocatalytic activity is further increased.
- the application of anodic oxidation photocatalysts to various types of titanium or titanium alloy substrates has been reviewed.
- titanium oxide has exhibited its photocatalytic activity (ultraviolet light response type) for ultraviolet light having a wavelength of about 380 nm or less.
- photocatalytic activity ultraviolet light response type
- a visible light response type that exhibits photocatalytic activity even for light in the visible light region (wavelength of 380 to 800 nm) through subsequent research and development.
- titanium oxide photocatalysts that is, titanium oxide photocatalysts having a small band gap have been developed.
- the visible light responsive titanium oxide photocatalyst refers to a titanium oxide photocatalyst that exhibits photocatalytic activity with respect to visible light having a wavelength longer than 380 nm, such as sunlight and light from a white fluorescent lamp.
- the titanium oxide film contains nitrogen or the titanium oxide film contains sulfur, carbon, fluorine or the like.
- Patent Documents 1 and 2 and Non-Patent Document 1 have proposed techniques relating to a photocatalyst composed of visible light responsive titanium oxide in which sulfur is contained in a titanium oxide film.
- Patent Document 1 Japanese Patent Application Laid-Open No. 2010-298378 discloses a method of forming rutile titanium dioxide excellent in photocatalytic activity in which sulfur is doped on the surface of a metal substrate made of titanium or a titanium alloy. .
- the surface of a base material made of titanium or a titanium alloy is applied 2.6% by weight to 14.1% by weight by applying a voltage (originally it should be mass%.
- an aqueous sulfuric acid solution having a concentration of 1) anodization is performed for 2 minutes or more at a voltage of 100 V or higher, followed by heat treatment at 400 ° C. to 1000 ° C. for 1 hour or more.
- Patent Document 1 further describes that a metal substrate is processed in advance into a plate shape, a foil, or the like or a desired shape suitable for the intended use form.
- Patent Document 2 Japanese Patent Laid-Open No. 2011-120998 discloses a visible light responsive rutile titanium dioxide photocatalyst.
- the rutile-type titanium dioxide photocatalyst described in Patent Document 2 is a film prepared by nitriding a metal substrate made of titanium or a titanium alloy, anodizing the nitridated substrate, and anodizing the film. It can be obtained by heat treatment.
- This anodizing treatment is carried out in an aqueous sulfuric acid solution having a sulfuric acid concentration of 0.02 to 1.6 mol / L by applying a potential of 100 to 300 ⁇ V for a range of about 10 to about 60 minutes.
- Such rutile-type titanium dioxide photocatalyst is doped with nitrogen and sulfur and exhibits high photocatalytic activity in the visible light region.
- the metal base material is previously processed into a plate shape, a foil, or the like or a desired shape suitable for the intended use form, and then anodized.
- Non-Patent Document 1 (“Creation of titanium dioxide photocatalyst by anodizing treatment", “Materia”, Vol. 49, No. 2, 2010), an aqueous solution of sulfuric acid was used as an electrolytic bath to anodize titanium plates.
- the titanium plate on which the anodized oxide film (titanium dioxide film) is formed is fired at 723 K for 4 hours in the atmosphere to have a porous surface and contain sulfur.
- This Non-Patent Document 1 discloses the matters described in the following (1) to (3).
- the rutile-type titanium dioxide described in Patent Document 1 is applied to the surface of a base material made of titanium or a titanium alloy in a sulfuric acid aqueous solution having a concentration of 2.6 wt. Manufactured by anodizing for more than a minute and then heat-treating at 400 ° C to 1000 ° C for more than 1 hour. When anodizing is performed in an aqueous solution, the elution of the surface of the titanium foil is caused and progressed by a high-concentration sulfuric acid aqueous solution, so that an uneluting portion that should originally be responsible for maintaining the shape of the foil, thin plate, etc. (unoxidized titanium, titanium (Alloy part) is lost in a short time, through holes are generated, and there is a risk that problems such as tattering easily occur.
- the titanium dioxide film of Patent Document 2 is a rutile type, but a visible light responsive photocatalyst body provided with a titanium oxide film having photocatalytic activity by subjecting a titanium substrate having a small thickness to anodization treatment and heat treatment. Difficult to form efficiently and with stable quality.
- an aqueous solution containing sulfuric acid is used as the electrolytic bath, if the concentration of sulfuric acid is not set appropriately, the surface of the titanium thin plate made of titanium or a titanium alloy may be eluted in the anodizing treatment. There is a need for further improvements.
- Non-Patent Document 1 describes that a titanium plate produced with a sulfuric acid concentration of 0.02 mm is anatase type, has a surface with pores of about 170 mm, and an oxide film thickness of about 330 mm. However, it is not disclosed to stably and highly accurately form a titanium dioxide film having only an anatase type crystal structure on a thin titanium foil, titanium thin plate, or the like.
- an object of the present invention is to provide a visible light response excellent in antibacterial property, in which a titanium oxide film containing sulfur and a crystal structure of titanium dioxide consisting only of anatase is formed on the surface of a thin substrate of titanium or a titanium alloy. It is to provide a shaped photocatalyst and a method for producing the same.
- the visible light responsive photocatalyst of the present invention is prepared by subjecting the surface of a titanium or titanium alloy substrate to an anodizing treatment using an electrolytic bath containing sulfur, and then heating the anodized substrate.
- the crystal structure of titanium dioxide contained in the titanium oxide film is an anatase type crystal structure.
- the titanium oxide film preferably contains 0.7 to 2.2 atomic% of sulfur.
- the film thickness of the titanium oxide film is preferably 200 nm or less.
- the pore width W is preferably 50 to 100 nm when the average value of the maximum value and the minimum value of the pore width of the micropores is defined as the pore width W.
- the base material is long and is continuously anodized by being guided to a continuous anodizing apparatus.
- the substrate has a foil shape or a plate shape.
- the substrate preferably has a punching shape or a mesh shape in which fine through holes penetrating from the front surface to the back surface are arranged at a predetermined interval.
- the base material is preferably formed by plain weaving a wire made of titanium or a titanium alloy in a mesh shape.
- photocatalytic activity for wavelengths in the visible to ultraviolet range.
- the antibacterial activity value (R) obtained by a photocatalytic antibacterial test based on JIS R1702 is 2.0 or more.
- micropores When the surface of the oxide film is observed with a scanning electron microscope, there are 30 or more micropores having a pore width W of 50 to 100 nm within a square range of 1000 to 1000 mm in length and width. Is preferred.
- the surface of the base material is subjected to an anodizing treatment using an electrolytic bath containing 0.01 mol / L to 0.2 mol / L of sodium thiosulfate, followed by a heat treatment.
- the applied voltage of the anodizing treatment is + 70V to + 140V
- the anodizing time is 10 seconds to 60 seconds
- the bath temperature of the electrolytic bath of the anodizing treatment is 1 ° C to 30 ° C
- the heat treatment is It is preferable to carry out the reaction at a temperature of 380 ° C. to 620 ° C. in an oxidizing atmosphere.
- the electrolytic bath preferably further contains 0.005 mol / L to 0.1 mol / L of potassium iodide.
- a long base material is used as the base material, and the long base material is guided to a continuous anodizing apparatus and continuously subjected to anodizing treatment, and then continuous with the anodized long base material. It is preferable to perform heat treatment.
- the visible light responsive photocatalyst of the present invention can exhibit the following effects.
- the visible light responsive photocatalyst of the present invention comprises a base material made of titanium or a titanium alloy and having a thickness of 0.005 mm to 0.6 mm, the crystal structure of titanium dioxide includes only anatase type, and the surface has micropores. Since the porous titanium oxide film having the above is provided, when the photocatalytic antibacterial test according to JIS R-1752 is carried out, the antibacterial activity value (R) has a stable quality of 2.0 or more.
- the visible light responsive photocatalyst of the present invention comprises an electrolytic bath containing titanium thiosulfate or sodium thiosulfate and potassium iodide on a base material made of titanium or a titanium alloy and having a thickness of 0.005 mm to 0.6 mm. Since the anodized titanium thin plate is heat-treated after the anodizing treatment, the photocatalyst having a titanium oxide film having a visible light response by containing sulfur on the surface of the titanium thin plate is stable and stable. It can be manufactured with high accuracy. In particular, a long titanium thin plate is used as a base material.
- the long base material After the long base material is guided to a continuous anodizing device and continuously anodized, it is continuously applied to the long base material that has been anodized.
- a titanium oxide film By subjecting to heat treatment, a titanium oxide film can be stably and highly accurately formed on a long and thin titanium substrate.
- the visible light responsive photocatalyst is processed into an appropriate shape and size according to the application, and the photocatalytic activity provided with visible light responsiveness to various devices and components thereof. In particular, it can be applied as a member excellent in antibacterial properties.
- FIG. It is a graph which shows the relationship between the density
- FIG. It is a graph which shows the relationship between the temperature of an electrolytic bath, and an antibacterial activity value (R) about the visible light response type photocatalyst body of Example 4.
- FIG. It is a graph which shows the relationship between the applied voltage at the time of an anodizing process, and an antibacterial activity value (R) about the visible light response type photocatalyst body of Example 5.
- FIG. It is a graph which shows the relationship between the anodizing time and antibacterial activity value (R) about the visible light response type photocatalyst of Example 6.
- Example 4 is a photograph (magnification: 30,000 times) when the surface of the titanium oxide film formed on the surface of the visible light responsive photocatalyst of Conventional Example 1 is imaged with a scanning electron microscope.
- 6 is a photograph (magnification: 30,000 times) when the surface of the titanium oxide film formed on the surface of the visible light responsive photocatalyst of Conventional Example 2 is imaged with a scanning electron microscope.
- the visible light responsive photocatalyst body of the present invention has a base material and a titanium oxide film formed on the surface of the base material.
- the titanium oxide film exhibits a function as a photocatalyst, particularly an excellent photocatalytic activity for visible light.
- the material of the substrate used in the present invention is pure titanium (1 to 4 types) defined by JIS standards, or a titanium alloy containing Pd, Ni, Cr, Al, V, or the like. In the following description, pure titanium or a titanium alloy may be collectively referred to as “made of titanium”.
- a base material used in the present invention a titanium foil-like or thin plate-like base material, a punching-like or mesh-like base material obtained by punching a large number of holes in a titanium foil-like or plate-like base material by pressing or the like
- a mesh-like base material obtained by plain weaving a wire made of titanium having a thickness of about 0.3 to 1 mm or less.
- the mesh-like base material is desirably used when producing a photocatalyst used for a filter member of an air cleaner or a wastewater treatment apparatus.
- the thickness of the visible light responsive photocatalyst having a mesh-like sheet structure is preferably about 0.5 mm to 2 mm in consideration of the ease of processing a plain weave of titanium wire.
- titanium foil As a titanium foil-like or thin plate-like substrate (hereinafter referred to as “titanium foil”), a titanium plate is rolled to a thickness of about 0.2 mm to 1.0 mm by cold rolling, and further A long (also called “band” or “coil”) titanium foil rolled to a thickness of about 0.005 mm to 0.6 mm (5 ⁇ m to 600 ⁇ m) by cold rolling can be used.
- a long (also called “band” or “coil”) titanium foil rolled to a thickness of about 0.005 mm to 0.6 mm (5 ⁇ m to 600 ⁇ m) by cold rolling can be used.
- the punched base material guides the titanium foil to a punching device (punch press) and, for example, minute holes (round, square, mesh-like minute gaps, etc.) in the longitudinal direction at predetermined intervals. It can be manufactured by punching multiple rows.
- the width of the punched or mesh gap is preferably 0.1 to 0.2 mm.
- Such a punched or mesh-like long visible light responsive photocatalyst body is cut into an appropriate size and used as a filter member for removing harmful substances (such as sulfides) contained in waste water or exhaust gas. Can be used.
- the titanium oxide film is a porous film containing sulfur and having fine pores on the surface, and the crystal structure of titanium dioxide is anatase type. Thereby, even if it is a case where a thin titanium oxide film is provided on a foil-like or thin plate-like substrate, it has a high antibacterial activity value (R) of 2.0 or more as a visible light responsive photocatalyst.
- the sulfur content is preferably 0.7 to 2.2 atomic%, and more preferably 0.7 to 1.6 atomic%.
- the thickness of the titanium oxide film is preferably 200 nm or less.
- Degreasing treatment and pickling treatment Before the anodizing treatment is performed on the surface of the substrate, a degreasing treatment and a pickling treatment are performed. Degreasing treatment and pickling treatment can be performed by conventional means.
- Titanium foil that has been degreased and pickled is introduced into an anodizing device filled with an electrolytic bath and run at a predetermined speed while anodizing the surface of the titanium foil. Apply processing.
- This anodizing apparatus is an apparatus (continuous anodizing apparatus) that can continuously perform anodizing treatment while sequentially running through the apparatus from the beginning to the end of a coiled long titanium foil. is there.
- a titanium oxide film containing sulfur on the surface of the titanium foil is obtained by feeding the titanium foil in the electrolytic bath in the continuous anodizing apparatus and feeding the titanium foil to perform anodizing treatment for a predetermined time. It is formed.
- an aqueous sodium thiosulfate solution having a concentration of 0.01 to 0.2 mol / L can be used.
- the reason for selecting the above sodium thiosulfate as the electrolytic bath for anodizing is as follows.
- a conventional sulfuric acid bath using sulfuric acid has a strong acidity, and thus may adversely affect a titanium oxide film formed on the surface of a long foil-like titanium thin plate by anodization. Therefore, an aqueous sodium thiosulfate solution was selected as an electrolytic bath containing sulfur and having a strong chelating action (bonding to titanium ions by thiosulfate ions) and serving as an oxidizing agent.
- the concentration of the sodium thiosulfate aqueous solution is preferably from 0.01 to 0.2 mol / L, more preferably from 0.05 to 0.1 mol / L.
- the anodizing time is preferably 10 seconds to 60 seconds, more preferably 10 seconds to 30 seconds, and even more preferably 20 seconds to 25 seconds.
- the bath temperature of the electrolytic bath is preferably 1 ° C. to 30 ° C., more preferably 5 ° C. to 15 ° C., and further preferably 8 ° C. to 12 ° C.
- a titanium oxide film having an antibacterial activity value (R) of 2.0 or more is formed by forming a porous titanium oxide film containing sulfur and having fine pores on the surface of the substrate made of a titanium foil. Can be obtained stably.
- any of the following (Means 1) and (Means 2) can be adopted.
- the feeding roller used to move the titanium foil in the anodizing device is made of a conductive member, and the anode of the power supply device for anodizing treatment is used as this means. It is a method of connecting a feed roller and applying a voltage from the feed roller to a long titanium foil. The cathode is placed in an appropriate place in the electrolytic bath at a predetermined distance from the titanium foil.
- a titanium foil is arranged in a direction perpendicular to the upper surface of the electrolytic bath, and one end side in the width direction of the titanium foil Is projected from the upper surface of the electrolytic bath.
- One end side in the width direction of the titanium foil protruding from the upper surface of the electrolytic bath can be detachably held at a predetermined interval, and a plurality of conductive clips that move in synchronization with the movement of the titanium foil are installed.
- the conductive clip is connected to the anode of the anodizing power supply, and the cathode is installed at an appropriate place in the electrolytic bath.
- the cathode is, for example, a cathode plate having a predetermined distance from the surface of the titanium foil moving in the electrolytic bath and having a width slightly longer than the width of the titanium foil.
- the (Means 2) can reliably and stably apply a voltage to the titanium foil. It is desirable to adopt (Means 2) in order to manufacture In addition, it becomes possible to anodize both or one side of the titanium foil used as a base material by changing the arrangement position of the cathode plate arrange
- the applied voltage is preferably + 70V to + 140V, more preferably + 80V to + 100V. Within this range, a titanium oxide film having a stable and good antibacterial activity value can be obtained.
- a long titanium foil that has been subjected to washing and drying treatment is guided to a continuous heating device, and is heated at a predetermined temperature and time while running through the device at a predetermined speed.
- the crystal structure of titanium dioxide contained in the titanium oxide film containing sulfur formed on the surface of the long titanium foil becomes an anatase type.
- a photocatalyst having high response to visible light (photocatalytic activity) can be obtained.
- the long titanium foil (photocatalyst body) subjected to the heat treatment is cut so as to have a predetermined size according to the application, if necessary.
- the temperature of the heat treatment is preferably 400 ° C. to 600 ° C., more preferably 430 ° C. to 500 ° C., and most preferably 440 ° C. to 460 ° C.
- the heating temperature is less than 400 ° C., the entire titanium oxide film does not contain a uniform anatase-type crystal structure, and the response (photocatalytic activity) to visible light of the titanium oxide film is insufficient.
- the heating temperature exceeds 600 ° C., as shown in FIG. 1, the rutile crystal structure is included in the crystal structure of the titanium oxide film and the titanium oxide film itself peels off, which is not desirable.
- the heat treatment is preferably performed in an oxidizing atmosphere containing oxygen, and particularly preferably performed in a simple air atmosphere.
- the heat treatment time is preferably 40 seconds to 80 seconds, and more preferably 50 seconds to 70 seconds.
- the degreasing treatment, pickling treatment, anodizing treatment, washing / drying treatment, and heat treatment of the long titanium foil are performed as described above. You may perform each process continuously using the manufacturing line which connected each processing apparatus. Thereby, the manufacturing efficiency of a long photocatalyst body can be improved, and manufacturing cost can be reduced significantly.
- a device from degreasing treatment to washing / drying treatment of a long titanium foil may be lined, and a device for heat treating the long titanium foil may be a separate line.
- the length of one long titanium foil (coil) serving as a base material for the photocatalyst is preferably from several meters to several hundred meters, and more preferably from 50 mm to 1000 mm.
- the width of the titanium foil (the width in the direction perpendicular to the longitudinal direction) is preferably about 80 mm to 400 mm, although it is based on the specifications of each device.
- the long photocatalyst according to the present invention produced by the above method may be cut so as to have an appropriate length and width according to the intended use. Therefore, the photocatalyst body of the present invention includes both a long photocatalyst body or a photocatalyst body cut to an appropriate size.
- Example 1 As the base material, eight kinds of coiled long foil-like titanium thin plates made of pure titanium (1 type) having a length of 100 m, a thickness of 80 ⁇ m (0.08 mm) and a width of 125 mm were used.
- the base material is passed through an alkaline degreasing solution at a temperature of 60 ° C. to perform a degreasing treatment.
- HF hydrogen fluoride
- H 2 O 2 5% by mass of H 2 O 2
- HNO 3 The pickling treatment was carried out by allowing the pickling solution to pass through.
- the base material was successively subjected to anodizing treatment and heat treatment from the start end to the end under the following conditions.
- the conditions for the anodizing treatment were as follows.
- the time for the anodizing treatment was determined by setting the speed at which the long foil-like titanium thin plate travels in the electrolytic bath of the continuous anodizing device.
- -Electrolytic bath aqueous solution containing 0.1 mol / L sodium thiosulfate-Electrolytic bath temperature: 10 ° C ⁇
- Applied voltage DC 100V ⁇
- Current density 1.4A / dm 2 ⁇
- Anodizing time 22.5 seconds (conditions for heat treatment) The conditions for the heat treatment were the following eight temperatures. The heating time was determined by setting the traveling speed in the continuous heating device for the long foil-like titanium thin plate. ⁇ Heating time: 60 seconds ⁇ Heating temperature: 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C
- the crystal structure of titanium dioxide contained in the titanium oxide film formed on the surface of the foil-like titanium sheet heat-treated at each heating temperature was analyzed by X-ray diffraction [XRD (X-Ray Diffraction)].
- Fig. 1 shows X-ray diffraction results L1 to L7 for seven heating temperatures of 400 ° C to 700 ° C.
- the heating temperature was 400 ° C. (L1) to 600 ° C.
- FIG. 2 (A) shows the X-ray diffraction result when the heating temperature is 450 ° C.
- FIG. 2 (B) shows the X-ray diffraction result when the heating temperature is 750 ° C.
- the crystal structure of titanium dioxide contained in the titanium oxide film when the heating temperature was 450 ° C. was all anatase type.
- FIG. 2B when the heating temperature was 750 ° C., it was confirmed that the titanium oxide film contained anatase type and rutile type crystal structures.
- the thickness of the titanium oxide film is 100 to 200 nm, and when the temperature of the heat treatment shown in FIG. 2 (B) is 750 ° C.
- the film thickness of the titanium film was 250 to 300 nm. The reason why the film thickness becomes thicker than 450 ° C. when the temperature of the heat treatment is 750 ° C. can be presumed that the generation of the titanium oxide film was promoted because the heating temperature was set high.
- Example 2 About the foil-like titanium thin plate when the temperature of the heat treatment in Example 1 is 450 ° C., the vicinity of the start end (position about 2 m from the start end) and the vicinity of the end (about 2 m start end from the end)
- the antibacterial activity value (R) was measured for the sulfur content contained in the titanium oxide film formed at the position and the samples collected from these locations.
- the content of sulfur contained in the titanium oxide film was measured at a depth of 20 nm from the surface of the titanium oxide film.
- the antibacterial activity value (R) was determined by a photocatalytic antibacterial test in accordance with JIS R-1752 (an antibacterial test method for visible light responsive photocatalyst processed products). These measurement results are shown in Table 1.
- the titanium oxide film formed on the surface of the foil-like titanium thin plate by heat treatment at a temperature as low as 450 ° C. contains only titanium dioxide having a sulfur-containing anatase type crystal structure. It was confirmed that the photocatalytic activity having visible light response was provided even when the film thickness was 200 nm or less.
- the long photocatalyst foil (photocatalyst body) having visible light responsiveness has a sulfur content and an antibacterial activity value (R) value in the vicinity of the start end and the end thereof. No significant difference was observed, and the photocatalytic activity having stable visible light responsiveness was confirmed over the entire length of the long foil-like titanium thin plate (photocatalyst).
- Example 3 shows the conditions for anodizing.
- a foil-like titanium thin plate made of pure titanium foil (1 type) having a length of 50 m, a thickness of 0.08 mm (80 ⁇ m), and a width of 125 mm was used as the substrate.
- the temperature of the electrolytic bath is 10 ° C.
- the applied voltage is 100 V
- the treatment time is 20 seconds
- the concentration of the electrolytic bath of the sodium thiosulfate aqueous solution shown in Table 2 is seven concentrations (0.01, 0.02, 0.05, 0.06, 0.1, 0.15 and 0.2 mol / L), respectively, to produce photocatalysts.
- the other production conditions were the same as in Example 2.
- mol / L indicates the concentration (mol / liter) of the electrolytic bath.
- Example 4 Table 3 shows the conditions for anodizing.
- the concentration of the electrolytic bath is 0.1 mol / L, the applied voltage is 100 V, the treatment time is 20 seconds, and the temperature of the electrolytic bath shown in Table 3 is 5 types (1 ° C, 5 ° C, 10 ° C, 20 ° C, 30 ° C). C.) to prepare a photocatalyst body.
- the other production conditions were the same as in Example 2.
- an antibacterial activity value (R) of 2.0 or higher can be obtained when the temperature of the electrolytic bath is set to 1 ° C. to 30 ° C., but the highest antibacterial activity value is set at 5 ° C. (R) could be obtained.
- the thickness of the titanium oxide film formed on the surface of the photocatalyst was 130 to 190 nm.
- the thickness of the titanium oxide film tended to increase.
- Example 5 Table 4 shows the conditions for anodizing.
- the concentration of the electrolytic bath is 0.1 mol / L
- the temperature of the electrolytic bath is 10 ° C
- the treatment time is 20 seconds
- the applied voltages shown in Table 4 are five types of applied voltages (50 V, 60 V, 70 V, 80 V, 100 V and 120 V), respectively, to produce a photocatalyst.
- the other production conditions were the same as in Example 2.
- Example 6 Table 5 shows the conditions for performing the anodizing treatment.
- the concentration of the electrolytic bath is 0.1 mol / L
- the applied voltage is 100 V
- the temperature of the electrolytic bath is 10 ° C
- the treatment times shown in Table 4 are five treatment times (10 seconds, 15 seconds, 20 seconds, 30 seconds, 60 seconds) to produce a photocatalyst body.
- the other production conditions were the same as in Example 2.
- an antibacterial activity value (R) of 2.0 or more was obtained when the anodizing treatment was performed for 10 to 60 seconds.
- an antibacterial activity value (R) near 2.5 was obtained at a treatment time of 15 to 30 seconds. Therefore, it is possible to produce a photocatalyst capable of obtaining a high antibacterial activity value (R) from a long foil-like titanium thin plate even when the anodizing time is as short as 15 to 30 seconds. There was found.
- the film thickness of the titanium oxide film formed on the surface of the photocatalyst was 170 to 180 nm.
- the sulfur content and antibacterial activity value (R) contained in the titanium oxide film of the photocatalyst of Example 3 were determined by the same method as in Example 2. The relationship between the sulfur content of the titanium oxide film and the antibacterial activity value (R) is shown in FIG.
- an antibacterial activity value (R) of 2.0 or more can be obtained when the content of sulfur contained in the titanium oxide film is at least 0.7 to 2.2 atomic%. Further, as described above, it was found that an antibacterial activity value (R) of 2.0 or more can be obtained even when the titanium oxide film has a very thin thickness of 200 nm or less.
- Example 7 is an aqueous solution of sodium thiosulfate having a concentration of 0.06 mol / L
- Example 8 is an aqueous solution of sodium thiosulfate having a concentration of 0.02 mol / L and potassium iodide having a concentration of 0.01 mol / L.
- Anodizing treatment was performed.
- the reason why potassium iodide is contained in the electrolytic bath is the same idea as that in the case where sodium thiosulfate is used as the electrolytic bath, and the ionic state produced by sodium thiosulfate and potassium iodide is thiosulfuric acid. Since there is much sulfur amount compared with sodium, it is estimated that the visible light responsiveness and antibacterial activity value (R) of the titanium oxide film formed on the foil-like titanium thin plate are increased.
- Example 1 the electrolytic bath was anodized with a 0.02 mol / L sulfuric acid aqueous solution, and in Conventional Example 2, the electrolytic bath was anodized with a 0.05 mol / L sulfuric acid aqueous solution.
- Photographs of the surface of the titanium oxide film formed on the surface of the foil-like titanium thin plate (of the visible light responsive photocatalyst) of Examples 7 and 8 and Conventional Examples 1 and 2 taken with a scanning electron microscope (magnification 30,000 times) ) Are shown in FIG. 5 (A), FIG. 5 (B), FIG. 6 (A) and FIG. 6 (B), respectively.
- the surface of the titanium oxide film was made of a porous material having an infinite number of fine pores (pores) 1a.
- the photograph of FIG. 5 (A) was baked on a photographic paper, then measured on a scale and converted from the magnification. As a result, the diameter of the pore was estimated to be 50 to 100 nm.
- Example 7 In the photograph shown in FIG. 5 (B), as in Example 7, it was observed that the surface of the titanium oxide film was made of a porous material in which an infinite number of fine pores 1b were present. From the photograph of FIG. 5B, the diameter of the pore 1b was measured by the same method as in Example 7. As a result, it was 50 to 100 nm as in Example 7.
- the surfaces of the titanium oxide films of the conventional examples 1 and 2 are made of a porous material having numerous pores 1c and 1d, respectively.
- the shape was a mixture of substantially circular pores and elliptic pores.
- the diameters of these pores 1c and 1d were measured by the same method as in Example 7, it was about 170 nm and about twice as large as Examples 7 and 8.
- pores (1a 1b, 1c, 1d) were measured. This distribution density is measured in five square areas of 1000 mm ⁇ 1000 mm from the center (area 1 shown in Table 7) and four corners (area 2 to area 5 shown in Table 7). Was selected, the number of pores present in this region was measured, and the average value of these values was defined as the average value of the pore distribution density. Table 7 shows the measurement results of the distribution density of the pores (1a, 1b, 1c, 1d).
- the distribution density of pores indicates the number in the region of 1000 nm x 1000 nm in length and width.
- the average distribution density of pores (pores) in a square region of 1000 nm ⁇ 1000 nm on the surface of the titanium oxide film is 38.8 and 34.2 in Examples 7 and 8, respectively.
- Conventional Examples 1 and 2 were 20.6 and 22.6, respectively, and the distribution density was lower by about 50% than Examples 7 and 8. This is because when the electrolytic bath contains sodium thiosulfate or sodium thiosulfate and potassium iodide, the pore diameter becomes smaller than when the electrolytic bath contains sulfuric acid, thereby increasing the surface area of the titanium oxide film. This shows that the photocatalytic activity is improved.
- Example 9 For the visible light responsive photocatalyst having a sodium thiosulfate concentration of 0.02 mol / L in Example 3, the sulfur content, photocatalytic antibacterial test for visible light, and photocatalytic antibacterial for ultraviolet light were conducted in the same manner as in Example 2.
- An antibacterial activity value (R) was determined by conducting a sex test.
- the antibacterial activity value (R) in the photocatalytic antibacterial test for visible light was 2.04, and the antibacterial activity value (R) in the photocatalytic antibacterial test for ultraviolet light was 2.68. Thereby, it can be judged that the photocatalyst body of this invention has photocatalytic activity with respect to visible light and ultraviolet light.
- the sulfur content of the titanium oxide film formed on the surface of the photocatalyst was 1.1 atomic% at a depth of 20 nm from the surface of the titanium oxide film.
- the visible light responsive photocatalyst based on the thin foil-like titanium plate of the above embodiment is used as various members (photocatalyst members) required for exhibiting visible light responsiveness, for example, various medical devices and the like.
- the present invention can be utilized as an effective member for exhibiting antibacterial properties, as a sheet member or a packaging member for packaging or housing these devices and parts, and the devices and parts thereof.
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Abstract
Description
(1)陽極酸化時の電解浴の硫酸濃度によって生成する二酸化チタン膜は、表面組織、膜厚、結晶構造が大きく変化する。例えば、硫酸濃度が0.02 Mで作製したチタン板の表面には約170 nmの細孔が観察され、酸化膜厚は約330 nmであった。
(2)電解浴中の硫酸濃度の増加とともに、細孔の形状は丸くなって、1.2 Mでは950 nmになった。また硫酸濃度の増加とともに、アナターゼのピーク強度が減少し、ルチルのピーク強度が増す。
(3)可視光応答性に優れる1.2 Mの硫酸浴で作製し陽極酸化膜中の硫黄濃度は約1100 ppmであり、0.02 Mで作製した二酸化チタン膜と比べて1桁小さいが、このことは硫酸濃度に応じてバンド構造が変化することを示唆している。
(1)本発明の可視光応答形光触媒体は、チタン又はチタン合金製からなる厚さ0.005 mm~0.6 mmの基材表面に、二酸化チタンの結晶構造がアナターゼ型のみを含み、表面に微細孔を有する多孔質な酸化チタン皮膜を設けているので、JIS R-1752に準拠した光触媒抗菌性試験を実施したときに、抗菌活性値(R)が2.0以上の安定した品質を有する。
本発明の可視光応答形光触媒体は、基材と、該基材の表面に形成された酸化チタン皮膜とを有する。酸化チタン皮膜は光触媒としての機能、特に可視光に対して優れた光触媒活性を発揮する。本発明に用いる基材の材質は、JIS規格で規定されている純チタン(1種~4種)、もしくはPd、Ni、Cr、Al、V等を含有するチタン合金である。以下の説明において、純チタン又はチタン合金のことを総称して「チタン製」と記載する場合がある。
本発明の光触媒体の製造工程において、長尺のチタン製箔に光触媒としての機能を有する酸化チタン皮膜を形成する方法の一例を以下説明する。
基材表面に陽極酸化処理を施す前に、脱脂処理及び酸洗処理を施す。脱脂処理及び酸洗処理は従来の手段で行うことができる。
脱脂処理及び酸洗処理を施したチタン製箔を電解浴が充填されている陽極酸化装置内に導いて所定の速度で走行させながら、このチタン製箔の表面に陽極酸化処理を施す。この陽極酸化装置は、コイル状の長尺のチタン製箔の始端部から終端部までを、順次装置内を走行させながら連続して陽極酸化処理を行うことができる装置(連続陽極酸化装置)である。この連続陽極酸化装置内の電解浴中にチタン製箔を走行させながらチタン製箔に給電して所定時間の陽極酸化処理を行うことにより、チタン製箔の表面に硫黄を含有した酸化チタン皮膜が形成される。
この手段は従来から広く採用されている方法であって、陽極酸化装置内においてチタン製箔を移動させるために使用する送りローラを導電性部材から構成し、陽極酸化処理用電源装置の陽極をこの送りローラに接続し、送りローラから長尺のチタン製箔に電圧を印加する方法である。なお、陰極は電解浴内においてチタン製箔から所定の間隔をおいた適切な場所に設置する。
長尺の基材を連続的に陽極酸化処理することが可能な連続陽極酸化装置内において、チタン製箔を電解浴の上面に対して垂直方向に配置し、チタン製箔の幅方向の一端側を電解浴の上面から突出させる。電解浴の上面から突出したチタン製箔の幅方向の一端側を所定の間隔で着脱自在に把持でき、チタン製箔の移動と同期させて移動する複数個の導電性クリップを設置する。導電性クリップは陽極酸化処理用電源装置の陽極と接続し、陰極は電解浴内の適切な場所に設置する。陰極は、例えば、電解浴内を移動するチタン製箔の表面と所定の距離を設け、チタン製箔の幅より若干長い幅を有する陰極板とする。陽極酸化装置内にチタン製箔が浸入するとチタン製箔の幅方向の一端側を順次導電性クリップで把持し、導電性クリップが陽極酸化装置の出口近傍に達すると把持を解除する。これにより、陽極酸化装置内に浸入したチタン製箔には所定の電圧が印加されるので、陽極酸化処理が施されて、その表面に酸化チタンからなる皮膜を形成することが可能になる。
陽極酸化処理を施した長尺のチタン製箔の表面を洗浄・乾燥する。洗浄・乾燥処理は従来の手段で行うことができる。
洗浄・乾燥処理を施した長尺のチタン製箔を連続加熱装置に導いて所定の速度で装置内を走行させながら、所定の温度及び時間で加熱処理を施す。この加熱処理により、長尺のチタン箔の表面に形成された硫黄を含有する酸化チタン皮膜に含まれる二酸化チタンの結晶構造がアナターゼ型となる。これにより、可視光に対する応答性(光触媒活性)の高い光触媒体が得られる。加熱処理を施した長尺のチタン製箔(光触媒体)は、必要に応じて、その用途に対応させて所定の寸法になるように切断する。
基材として、長さが100 m、厚さが80μm(0.08 mm)、幅が125 mmの純チタン(1種)からなる8種のコイル状の長尺の箔状チタン薄板を用いた。この基材を温度60℃のアルカリ系脱脂液中に通過させてことにより脱脂処理を行い、HF(フッ化水素)を1質量%、H2O2を5質量%、HNO3を15質量%含む酸洗液中に通過させることにより酸洗処理を行った。
(陽極酸化処理の条件)
陽極酸化処理の条件は次の通りとした。なお陽極酸化処理の時間は、長尺の箔状チタン薄板を連続陽極酸化装置の電解浴内を走行させる速度を設定することにより決定した。
・電解浴 : 0.1mol/Lのチオ硫酸ナトリウムを含む水溶液
・電解浴の温度 : 10℃
・印加電圧 : 直流100V
・電流密度 : 1.4A/dm2
・陽極酸化処理の時間 : 22.5秒
(加熱処理の条件)
加熱処理の条件は、下記の8種の温度について実施した。なお加熱時間は、長尺の箔状チタン薄板の連続加熱装置内における走行速度を設定することにより決定した。
・加熱時間 : 60秒
・加熱温度 : 400℃、450℃、500℃、550℃、600℃、650℃、700℃、750℃
実施例1の加熱処理の温度を450℃としたときの箔状チタン薄板について、その始端部近傍(始端部から約2m終端部側の位置)と終端部近傍(終端部から約2m始端部側の位置)に形成された酸化チタン皮膜に含まれている硫黄の含有量と、これらの箇所から採取したサンプルについて抗菌活性値(R)を測定した。酸化チタン皮膜に含まれている硫黄の含有量は、酸化チタン皮膜の表面から深さ20 nmにおける含有量を測定した。抗菌活性値(R)は、JIS R-1752(可視光応答形光触媒加工製品の抗菌性試験方法)に準拠した光触媒抗菌性試験により求めた。これらの測定結果を表1に示す。
陽極酸化処理を行うための条件を表2に示す。基材として、長さが50 m、厚さが0.08 mm(80μm)、幅が125 mmの純チタン箔(1種)からなる箔状チタン薄板を用いた。電解浴の温度を10℃、印加電圧を100 V、処理時間を20秒とし、表2に示すチオ硫酸ナトリウム水溶液の電解浴の濃度を7種の濃度(0.01、0.02、0.05、0.06、0.1、0.15、0.2 mol/L)にそれぞれ設定し、光触媒体を製造した。それ以外の製造条件は実施例2と同じとした。
陽極酸化処理を行うための条件を表3に示す。電解浴の濃度を0.1 mol/L、印加電圧を100 V、処理時間を20秒とし、表3に示す電解浴の温度を5種の温度(1℃、5℃、10℃、20℃、30℃)にそれぞれ設定し、光触媒体を製造した。それ以外の製造条件は実施例2と同じとした。
陽極酸化処理を行うための条件を表4に示す。電解浴の濃度を0.1 mol/L、電解浴の温度を10℃、処理時間を20秒とし、表4に示す印加電圧を5種の印加電圧(50 V、60 V、70 V、80 V、100 V、120 V)にそれぞれ設定し、光触媒体を製造した。それ以外の製造条件は実施例2と同じとした。
陽極酸化処理を行うための条件を表5に示す。電解浴の濃度を0.1 mol/L、印加電圧を100 V、電解浴の温度を10℃とし、表4に示す処理時間を5種の処理時間(10秒、15秒、20秒、30秒、60秒)にそれぞれ設定し、光触媒体を製造した。それ以外の製造条件は実施例2と同じとした。
表6に示す陽極酸化処理と加熱処理の条件を用いた以外の製造条件は実施例2と同じとし、長尺の光触媒体を製造した。
実施例3のチオ硫酸ナトリウムの濃度が0.02 mol/Lの可視光応答形光触媒体について、実施例2と同様の方法で硫黄の含有量、可視光に対する光触媒抗菌性試験と、紫外光に対する光触媒抗菌性試験を実施して抗菌活性値(R)を求めた。可視光に対する光触媒抗菌性試験における抗菌活性値(R)は2.04であり、紫外光に対する光触媒抗菌性試験における抗菌活性値(R)は2.68であった。これにより、本発明の光触媒体は、可視光及び紫外光に対して光触媒活性を有していると判断できる。光触媒体の表面に形成された酸化チタン皮膜の硫黄含有量は酸化チタン皮膜の表面から深さ20 nmにおいて1.1原子%であった。
Claims (15)
- チタン又はチタン合金の基材の表面に硫黄を含有する電解浴を用いて陽極酸化処理を施した後、前記陽極酸化処理済みの基材に加熱処理を施して前記基材の表面に硫黄を含有し、表面に微細孔を有する多孔質な酸化チタン皮膜を形成した可視光応答形光触媒体であって、
前記基材の厚さは0.005 mm~0.6 mmであり、
前記酸化チタン皮膜に含まれる二酸化チタンの結晶構造はアナターゼ型結晶構造であることを特徴とする可視光応答形光触媒体。 - 前記酸化チタン皮膜は0.7~2.2原子%の硫黄を含有していることを特徴とする請求項1に記載の可視光応答形光触媒体。
- 前記酸化チタン皮膜の膜厚は200 nm以下であることを特徴とする請求項1又は2に記載の可視光応答形光触媒体。
- 前記微細孔の孔幅の最大値と最小値の平均値を孔幅Wとしたときに、前記孔幅Wは50~100 nmであることを特徴とする請求項1から請求項3のいずれかに記載の可視光応答形光触媒体。
- 前記基材は長尺であり、連続陽極酸化装置に導いて連続的に陽極酸化処理を施したことを特徴とする請求項1から請求項4のいずれかに記載の可視光応答形光触媒体。
- 用途に対応させて所定の寸法になるように切断されていることを特徴とする請求項5に記載の可視光応答形光触媒体。
- 前記基材が箔状又は板状であることを特徴とする請求項1から請求項6のいずれかに記載の光触媒体。
- 前記基材は、その表面から裏面に貫通する微細な貫通孔が所定の間隔で配列したパンチング状又は網目状であることを特徴とする請求項1から請求項6のいずれかに記載の可視光応答形光触媒体。
- 前記基材は、チタン又はチタン合金からなる線材をメッシュ状に平織りしてなることを特徴とする請求項1から請求項6のいずれかに記載の可視光応答形光触媒体。
- 可視光から紫外光の領域の波長に対して光触媒活性を備えていることを特徴とする請求項1から請求項9のいずれかに記載の可視光応答形光触媒体。
- JIS R1702に準拠した光触媒抗菌性試験により得られる抗菌活性値(R)が2.0以上であることを特徴とする請求項1から請求項10のいずれかに記載の可視光応答形光触媒体。
- 前記酸化皮膜の表面を走査型電子顕微鏡で観察したときに、縦横が1000 nm×1000 nmの正方形範囲内に、前記孔幅Wが50~100 nmの微細孔が30個以上存在していることを特徴とする請求項1から請求項11のいずれかに記載の光触媒体。
- 前記基材の表面にチオ硫酸ナトリウムを0.01 mol/L~0.2 mol/L含む電解浴を用いて陽極酸化処理を施した後、加熱処理を施すことにより請求項1から請求項12のいずれかに記載の可視光応答形光触媒体を製造する製造方法であって、
陽極酸化処理の印加電圧を+70 V~+140 Vとし、陽極酸化時間を10秒~60秒間とし、陽極酸化処理の電解浴の浴温度を1℃~30℃とし、加熱処理は酸化性雰囲気で380 ℃~620℃の温度で行うことを特徴とする光触媒体の製造方法。 - 前記電解浴はさらにヨウ化カリウムを0.005 mol/L~0.1 mol/L含むことを特徴とする請求項13に記載の可視光応答形光触媒体の製造方法。
- 前記基材として長尺の基材を使用し、前記長尺の基材を連続陽極酸化装置に導いて連続的に陽極酸化処理を施した後、陽極酸化処理済みの長尺の基材に連続的に加熱処理を施すことを特徴とする請求項13及び14に記載の光触媒体の製造方法。
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