JP2003193294A - Metallic member and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently decompose a substance as an object for decomposition, and to prevent the reduction of the durability of a metallic member. <P>SOLUTION: An anodic oxidation film 2 is formed on the surface of a base material 1 made of magnesium or a magnesium alloy. After that, many photocatalytic bodies 3 containing photocatalytic fine particles 4 and porous apatite 5 provided on the outer circumferential parts of the photocatalytic fine particles 4 are fixed to the anodic oxidation film 2. In the fixing of the photocatalytic bodies 3 to the anodic oxidation film 2, the photocatalytic bodies 3 are stuck to many fine pores 2a formed on the anodic oxidation film 2, and, after that, the fine pores 2a are subjected to sealing treatment with hot water. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal member having a photocatalyst fixed on the surface of a metal base material and a method for manufacturing the same.

[0002]

2. Description of the Related Art Titanium dioxide, which is a photocatalyst, decomposes various chemical substances that are difficult to decompose safely and easily by using light and moisture in the air without using harmful chemicals or heavy metals. . Moreover, since titanium dioxide itself does not change upon decomposition and only acts as a catalyst, it can be used semipermanently and is safe and harmless. Specifically, it is effective for decomposing various organic substances such as malodorous components, molds, bacteria, environmental hormones, and environmental pollutants such as dioxins.

As a metal member using a photocatalyst,
It is known that an anodized film (a film mainly composed of magnesium oxide having corrosion resistance) is formed on the surface of a base material made of magnesium or a magnesium alloy, and fine powder of titanium dioxide is further adhered to the anodized film. .

[0004]

However, the decomposition reaction by the photocatalyst does not occur unless the substance to be decomposed comes into contact with the photocatalyst at the same time that the photocatalyst is in contact with light, and the environmental pollutant diffuses in a wide range at a low concentration. Therefore, the decomposition efficiency of the environmental pollutants on the metal member was low and the treatment capacity was insufficient. In addition, titanium dioxide has an extremely high photocatalytic function, which not only decomposes organic environmental pollutants, but also gradually corrodes the anodized film and the base material underneath it. And the durability of the metal member is reduced.

The present invention has been made to solve the above problems, and a metal capable of efficiently decomposing a substance to be decomposed and preventing deterioration of durability. An object is to obtain a member and a manufacturing method thereof.

[0006]

A method of manufacturing a metal member according to the present invention comprises a step of forming an anodic oxide coating on the surface of a metallic base material, and a step of providing photocatalyst fine particles and an outer peripheral portion of the photocatalyst fine particles. The method includes a step of fixing a large number of photocatalyst bodies having a porous apatite present on the anodized film.

Further, a metal base material whose main component is magnesium is used. Furthermore, the anodized film is formed by an electrolytic bath using an alkaline aqueous solution. Furthermore, the electrolysis bath has a temperature of the alkaline aqueous solution of 15 to 100.
℃, 0.5~10A / dm ² of current density, the electrolysis treatment time is between 1 to 60 minutes. The electrolytic bath periodically inverts plus and minus by a plus-minus polarity reversing power supply.

Further, when fixing the photocatalyst to the anodic oxide coating, the photocatalyst is attached to a large number of pores formed in the anodic oxide coating, and then the pores are sealed with hot water.
Furthermore, before adhering the photocatalyst to the pores, a coloring material is put into the pores by a coloring treatment. In addition, before the anodic oxide coating is formed, a pattern of irregularities is formed on the surface of the base material.

The metal member according to the present invention comprises a metallic base material, an anodized film formed on the surface of the base material, and photocatalyst particles and a porous material provided on the outer peripheral portion of the photocatalyst particles. Apatite and a large number of photocatalysts adhered to the anodized film.

The photocatalyst fine particles are titanium dioxide. Further, the base material is made of a metal whose main component is magnesium.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a sectional view schematically showing a main part of a metal member according to Embodiment 1 of the present invention. In the figure, the substrate 1 is made of a metal containing magnesium as a main material, such as magnesium or a magnesium alloy. An anodized film (alumite film) 2 is formed on the surface of the substrate 1. A large number of photocatalysts 3 are fixed to the anodized film 2. Each photocatalyst body 3 includes photocatalyst fine particles 4 made of titanium dioxide, and the photocatalyst fine particles 4
And a porous apatite 5 provided on the outer peripheral portion of the.

Examples of the material of the substrate 1 include magnesium or magnesium alloys (for example, AZ91, AZ31, AZ61 containing aluminum and zinc). However, the present invention is not limited to these, and by electrolyzing a suitable aqueous electrolyte solution using the base material 1 as an electrode (electrolytic treatment), a coating containing an oxide having corrosion resistance as a main component can be formed on the surface of the base material 1. If so, other metals can also be used.

Next, a method of manufacturing the metal member shown in FIG.
explain. First, in order to manufacture the photocatalyst body 3,
OCP (a kind of calcium phosphate:
Ca ₈H₂(PO_Four)₆5H₂O) to become supersaturated
In a simulated body fluid at 37 ° C dissolved in
The photocatalyst fine particles 4 having a particle size of 1 nm to 1 μm are immersed.
Then, a pseudo body is formed so that the photocatalyst fine particles 4 do not precipitate.
Keep the above temperature while stirring the solution slowly.
As a result, OCP crystals are deposited on the surface of the photocatalyst fine particles 4.
Let As a result, the surface of the photocatalyst fine particles 4 has an aperture.
Tight 5 crystals are produced.

At this time, the crystal of the apatite 5 is plate-shaped and grows outward in the radial direction from the surface of the photocatalyst fine particles 4, so the surface of the photocatalyst fine particles 4 is covered with the porous apatite 5 and the apatite 5 is formed. Titanium dioxide is exposed at the bottom of the pores of No. 5. Apatite 5 is a type of ceramic and is chemically stable, so
It is not decomposed by the photocatalytic activity of titanium dioxide. The crystal form of titanium dioxide is preferably anatase, which has a high function as a photocatalyst.

On the other hand, in a bath of an aqueous electrolyte solution (electrolysis bath),
The metal base material 1 that has been subjected to pretreatment such as degreasing is immersed. Then, the base material 1 is set on the anode side and electrolyzed by a DC power source to form the anodized film 2 on the surface of the base material 1. Specifically, the anodic oxide coating 2 initially grows as a magnesium hydroxide coating. Then, the magnesium oxide film is formed by being dehydrated by baking. That is, Mg (OH) ₂ → MgO + H ₂ O.

Immediately after the formation, the surface layer of the anodic oxide coating 2 is
A large number of pores (fine recesses) 2a are formed. Various conditions at the time of forming the anodized film 2 need to be appropriately set according to the type of the selected base material 1. The thickness of the anodic oxide coating 2 is, for example, about 30 μm.

When the base material 1 made of magnesium or magnesium alloy is used, for example, sodium hydroxide (NaO) is used.
H), lithium hydroxide (LiOH), potassium hydroxide (KOH), rubidium hydroxide (RbOH), cesium hydroxide (CsOH), barium hydroxide (Ba (O
H) ₂ ), ammonium hydroxide (NH ₄ OH), calcium hydroxide (Ca (OH) ₂ ), calcium phosphate (Ca
PO ₃ ), calcium fluoride (CaF ₂ ), sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl ₂ ), calcium chloride (CaCl ₂ ),
Barium chloride (BaCl ₂ ), sodium carbonate (Na ₂ C
O ₃ ), potassium carbonate (K ₂ CO ₃ ), ammonia carbonate (NH ₄ CO ₃ ), magnesium carbonate (MgCO ₃ ), calcium carbonate (CaCO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), and the like. An electrolytic bath of an aqueous solution containing seeds, that is, an alkaline aqueous solution is used.

The temperature of the electrolytic bath, the current density on the anode (base material 1) side, and the electrolytic treatment time influence the diameter and depth of the pores 2a formed in the surface layer portion of the anodic oxide coating 2. For example, temperature 15 to 100 ° C., current density 0.5 to 10 A / dm
^{2. The} electrolytic treatment time is preferably in the range of 1 to 60 minutes. That is, by forming the anodic oxide coating 2 under these conditions, the diameter of the pores 2a (for example, about 0.4 μm) becomes larger than the particle diameter of the photocatalyst body 3, and the depth of the pores 2a becomes larger. Since it is more than the amount that the body 3 can stay, the photocatalyst body 3 can be adsorbed in the pores 2a.

Thereafter, the base material 1 having the anodic oxide coating 2 formed thereon is immersed in the dispersion liquid in which the photocatalyst 3 is dispersed while stirring. As a result, the surface of the anodic oxide coating 2 and the pores 2a are utilized by utilizing the adsorption action of the apatite 5.
The photocatalyst body 3 is adsorbed inside. After that, the base material 1 having the photocatalyst 3 adsorbed thereon is immersed in hot water (boiling water) to seal the pores 2a of the anodic oxide coating 2.

By the sealing treatment, the anodic oxide coating (magnesium oxide film) 2 grows and the pores 2a are closed. As a result, the photocatalyst body 3 has pores 2 on the surface of the anodic oxide coating 2.
a It is fixed while being exposed to the outside.

As another method for fixing the photocatalyst 3, another method of fixing the photocatalyst 3 is not provided, but the base material 1 is immersed in the electrolyte in which the photocatalyst 3 is dispersed, and the electrolyte is stirred. While performing the electrolytic treatment, the anodic oxide coating 2 is formed on the surface of the base material 1, and at the same time, the photocatalyst 3 is adsorbed on the surface of the anodic oxide coating 2 and in the pores 2a, and then the same sealing as above is performed. There is a method of performing pore treatment. It is also possible to adopt a method in which the substrate 1 on which the anodized film 2 is formed is immersed in boiling water in which the photocatalyst 3 is dispersed, and the photocatalyst 3 is adsorbed and the pores are simultaneously sealed.

Further, when the anodic oxide coating 2 is formed, electrolytic treatment may be performed with a plus / minus polarity reversal power source that periodically and positively outputs plus and minus. In this case, the base material 1
When it becomes an anode, the anodic oxide coating 2 is formed, and at the time of the cathode, a compound having adsorptivity is deposited in the pores 2a of the anodic oxide coating 2.

Since such compounds attract each other with the apatite 5, the photocatalyst body 3 penetrates deep into the pores 2a and is adsorbed. As a result, the entire photocatalyst 3
And the photocatalyst body 3 can be more firmly fixed.

Specifically, when the polarity is reversed (when a negative voltage is applied)
From between the magnesium substrate of the base material 1 and the innermost part of the pores 2a, that is, the thinnest part of the anodized film 2 before sealing,
A large amount of hydrogen gas is generated to try to destroy the thinnest part of the anodized film 2 before sealing. At this time, if the negative voltage is not controlled and the negative current becomes extremely large, the mechanical destructive action by a large amount of hydrogen gas takes precedence, and the growth of the coating film stops.

On the other hand, when the negative voltage is appropriately controlled and the negative current is suppressed, the anodic oxide coating 2 is appropriately broken, and the electric resistance value of the thinnest portion of the anodic oxide coating 2 before sealing is lowered. It This produces a thicker anodic oxide coating 2 than when using a DC power supply. As described above, the anodic oxide coating 2 generated by the polarity reversal is characterized in that the size of the pores 2a is uniform and large, and the thinnest portion is thin as compared with the case of using a DC power supply.

Examples of the positive / negative polarity reversal power supply include a high-speed current reversal power supply, an AC / DC combined power supply, and an AC / DC superposition power supply. The high-speed current reversal power supply can arbitrarily change the ratio between the positive output time and the negative output time in one cycle, and repeatedly outputs this cycle for ten to several tens of times. The AC / DC combined power source switches between DC and AC for output. The AC / DC superimposing power source superimposes DC and AC and outputs the result. The anodic oxide coating 2 is formed by setting the time at which the base material 1 side becomes a positive pole to be longer than the time at which it becomes a negative pole.

In the metal member constructed as described above, since the photocatalyst fine particles 4 covered with the porous apatite 5 having adsorptivity are fixed on the surface, they are suspended in air or dissolved in water. Decomposition substances such as environmental pollutants
It is adsorbed and captured by the apatite 5 and is supported while being in direct contact with the photocatalyst fine particles 4.

Further, since the apatite 5 is porous and the photocatalyst fine particles 4 are exposed at the bottoms of the pores thereof, the photocatalyst can be exposed to artificial light such as fluorescent lamps, incandescent lamps, mercury lamps or sunlight. The exposed portion of the fine particles 4 receives light, exhibits photocatalytic activity, and the decomposition target substance carried on the apatite 5 is decomposed.

Further, a substance to be decomposed which is not captured by the apatite 5 but is in direct contact with the photocatalyst fine particles 4 is similarly decomposed by the photocatalytic function of the photocatalyst fine particles 4 when receiving light. That is, a substance excited by the photocatalytic reaction is generated in the pores of the apatite 5, and the excited substance reacts with the decomposition target substance to decompose the decomposition target substance existing in the pores.

Furthermore, since the photocatalyst fine particles 4 are covered with the apatite 5 which is not easily corroded by the exciting substance, the photocatalyst fine particles 4 are not in direct contact with the anodic oxide coating 2, and the exciting substance does not affect the outside of the apatite 5. The anodized film 2 is not corroded. Further, since the surface is covered with the photocatalyst fine particles 4 and the apatite 5 which have extremely excellent corrosion resistance, the base material 1 can be protected from various corrosive substances. Therefore, the substance to be decomposed can be efficiently decomposed and the deterioration of durability can be prevented.

Even when not receiving light, apatite 5 adsorbs and traps environmental pollutants such as malodorous components, mold, bacteria, environmental hormones, and dioxins, which are diffused in a wide range at low concentrations. , It can also be decomposed together when receiving light later. Therefore, the purifying action is always exhibited regardless of day and night, and the environmental pollutants can be efficiently decomposed.

In addition, innumerable pores 2a are present in the surface layer portion of the anodic oxide coating 2, and the diameter of these pores 2a is made larger than the particle diameter of the photocatalyst 3 and the depth of the pores 2a is increased. The photocatalyst body 3 is fixed not only on the surface of the anodic oxide coating 2 but also in the pores 2a, because the photocatalyst body 3 is set to the extent that the photocatalyst body 3 can stay. In such a metal member, since the entire anodic oxide coating 2 is completely covered with the photocatalyst 3, the weather resistance and the corrosion resistance are excellent. Further, since the area occupied by the photocatalyst body 3 becomes large, the decomposition ability of the decomposition target substance becomes high.

Further, in the sealing treatment of the anodic oxide coating 2 with hot water such as boiling water or high temperature steam, the surface of the anodic oxide coating 2 and the wall surface of the pores are softened and altered, and the photocatalyst 3 becomes the anodic oxide coating 2. After familiarization, the anodic oxide coating 2 is hardened again. That is, after the surface of the anodized film 2 and the wall surface of the pores are partially dissolved by hot water, this dissolved product is hydrated and re-precipitated with the photocatalyst 3. As a result, the adhesion between the anodic oxide coating 2 and the photocatalyst body 3 is increased,
The peel strength of the photocatalyst body 3 is increased, and the durability is improved.
Therefore, it can be used under severe conditions.

When the above metal members are used in electric equipment such as mobile phones, ordinary telephones, personal computers, computer peripherals, and AV equipment, dust in the atmosphere that is routinely adsorbed by static electricity, Perspiration and cosmetics that adhere to humans can be decomposed and soiled in the environment of use. Also, in elevators, handrails in the car room,
The same antifouling effect can be obtained by being used for the operation panel in the hall and the car room.

Further, since the anodic oxide coating 2 has an insulating property, magnesium or magnesium alloy can be used as the material of the substrate 1 without separately providing an insulating coating. Therefore, light weight and high strength magnesium or magnesium alloy can be used at low cost.

Further, it is generally difficult to recycle the metal to which the paint adheres, but in the above metal member, both the anodic oxide coating 2 and the photocatalyst body 3 are inorganic and are excellent in recyclability. Conventionally, when using magnesium,
Although it is lightweight and inexpensive, it needs to be coated with 5 to 6 layers because it has a property of being easily oxidizable and combustible. However, the above metal members do not require coating, so magnesium and magnesium alloys are not required. Can be recycled.

Furthermore, if the above-mentioned metal members are used for building members such as sashes and panels, environmental pollutants can be efficiently removed from the living space. Therefore, in-hospital infection by pathogens such as MRSA (methicillin-resistant Staphylococcus aureus) It is possible to provide a comfortable and safe living space by preventing infection, sick house syndrome caused by volatile chemicals such as formaldehyde, odorous components, environmental hormones, and environmental damage caused by dioxins.

Further, since it is excellent in durability, weather resistance and corrosion resistance, it can be used for outdoor members such as outer walls and roofs,
It is possible to decompose and remove stains such as mold, exhaust gas, and algae attached to the surface. Further, since the apatite 5 has hydrophilicity, dirt such as sand dust or the like can be easily washed away with rainwater or the like. Therefore, it is possible to construct a building that is lightweight, robust, and has self-cleaning properties.

Embodiment 2. Next, FIG. 2 is a sectional view schematically showing a main part of a metal member according to a second embodiment of the present invention. In this example, before the photocatalyst 3 is attached to the pores 2a of the anodic oxide coating 2, the coloring material 6 is put into the pores 2a by performing a coloring treatment with a dye. Other configurations and manufacturing methods are similar to those of the first embodiment.

According to such a manufacturing method, it is possible to give an arbitrary color to the metallic luster of the surface of the metallic member. Also, a pattern can be added by performing partial coloring treatment.

Embodiment 3. Next, FIG. 3 is a partially enlarged sectional view of a metal member according to a third embodiment of the present invention. In this example, before the anodic oxide coating 2 is formed, a pattern of irregularities is formed on the surface of the base material 1. Other configurations and manufacturing methods are similar to those of the first embodiment. Further, the illustration of the photocatalyst body 3 is omitted.

According to such a manufacturing method, a three-dimensional pattern can be formed on the surface of the metal member, the degree of freedom in design can be expanded, and the designability can be improved.

[0043]

As described above, the method for producing a metal member of the present invention comprises the step of forming an anodized film on the surface of a metal base material, and the photocatalyst particles and the outer peripheral portion of the photocatalyst particles. Since a large number of photocatalysts having a porous apatite that is used are included in the step of fixing the photocatalyst to the anodized film, it is possible to efficiently decompose the substance to be decomposed and prevent deterioration of durability. it can.

Further, since a metal base material whose main component is magnesium is used, a lightweight and high-strength metal member can be obtained. Furthermore, since the anodic oxide coating is formed by an electrolytic bath using an alkaline aqueous solution, the anodic oxide coating having pores suitable for accommodating the photocatalyst can be easily formed. Furthermore, the electrolytic bath has an alkaline aqueous solution temperature of 15 to 100 ° C. and a current density of 0.5 to 10 A.
/ Dm ² , and the electrolytic treatment time is 1 to 60 minutes, so that the photocatalyst can be efficiently adsorbed in the pores of the anodized film, and a sufficient amount of the photocatalyst can be fixed to the anodized film. . In addition, since the electrolytic bath periodically and positively outputs positive and negative by a positive and negative polarity reversing power supply, the overall fixing rate of the photocatalyst can be increased and the photocatalyst can be more firmly fixed. .

Further, when fixing the photocatalyst to the anodic oxide coating, the photocatalyst is attached to a large number of pores formed in the anodic oxide coating, and the pores are sealed with hot water. The adhesion between the oxide film and the photocatalyst body is enhanced, the peel strength of the photocatalyst body is enhanced, and the durability is improved. Furthermore, since the coloring material is put into the pores by performing the coloring treatment before the photocatalyst is attached to the pores, the metallic luster of the surface of the metal member can be given an arbitrary color. Moreover, since a pattern due to unevenness is formed on the surface of the base material before the anodized film is formed, a three-dimensional pattern can be formed on the surface of the metal member, and the degree of freedom in design can be expanded. The designability can be improved.

The metal member according to the present invention comprises a metal base material, an anodized film formed on the surface of the base material, photocatalyst particles and a porous material provided on the outer peripheral portion of the photocatalyst particles. Since a large number of photocatalysts having apatite and fixed to the anodic oxide coating are provided, the substance to be decomposed can be efficiently decomposed and the deterioration of durability can be prevented.

Further, since titanium dioxide is used as the photocatalyst fine particles, the substance to be decomposed can be efficiently decomposed, and the deterioration of durability can be prevented.
Furthermore, since the base material is made of a metal containing magnesium as a main material, it is possible to obtain a lightweight and strong metal member.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a main part of a metal member according to a first embodiment of the present invention.

FIG. 2 is a sectional view schematically showing a main part of a metal member according to a second embodiment of the present invention.

FIG. 3 is a partially enlarged sectional view of a metal member according to Embodiment 3 of the present invention.

[Explanation of symbols]

1 substrate, 2 anodized film, 2a pores, 3 photocatalyst, 4 photocatalyst fine particles, 5 apatite, 6 colorant.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 37/02 301 A61L 9/00 C // A61L 9/00 C07D 319/24 C07D 319/24 B01D 53 / 36 J F Term (Reference) 4C080 AA09 BB04 CC01 MM02 NN01 QQ03 4D048 AA21 AA22 BA01X BA02X BA07X BA41X BA44X EA01 EA04 4G069 AA03 AA08 BA04A BA06A FC22 FB02FB02 FB02FB02 FA01 FB02FB01 FA01 FA02 CA01 FA02 CA01 CA02 CA01 FA02 CA01 FA11 CA11 CA11 FA02 CA01 FA02 CA01 FA02 CA01 FA11 CA02 FA17 CA01 CA02 FA01 FA02 CA01 FA02 CA01 FA11 CA02 CA01 CA11 FA02 CA01 CA11 CA02 FA01 FA02 CA01 FA02 CA01

Claims (11)

[Claims] 1. A step of forming an anodized film on the surface of a metal base material, and a large number of photocatalyst bodies having photocatalyst fine particles and porous apatite provided on the outer peripheral portion of the photocatalyst fine particles. A method of manufacturing a metal member, comprising the step of fixing to the anodized film. 2. The method for producing a metal member according to claim 1, wherein the base material is made of a metal containing magnesium as a main material. 3. The anodic oxide coating is formed by an electrolytic bath using an alkaline aqueous solution.
A method for manufacturing the described metal member. 4. The electrolytic bath has a temperature of the alkaline aqueous solution of 15 to 100 ° C. and a current density of 0.5 to 10 A / d.
The method for producing a metal member according to claim 3, wherein m ² and the electrolytic treatment time are 1 to 60 minutes. 5. The method for producing a metal member according to claim 3, wherein the electrolytic bath performs positive and negative polarity reversal output by a positive and negative polarity reversing power source. 6. When fixing the photocatalyst to the anodic oxide coating, after adhering the photocatalyst to a large number of pores formed in the anodic oxide coating, the pores are sealed with hot water. 6. The method according to claim 1, wherein the processing is performed.
The method for manufacturing a metal member according to any one of 1. 7. The method for producing a metal member according to claim 6, further comprising a step of applying a coloring material to the pores by performing a coloring treatment before the photocatalyst body is attached to the pores. . 8. The metal according to claim 1, further comprising a step of forming a pattern of irregularities on the surface of the base material before forming the anodized film. A method of manufacturing a member. 9. A metal base material, an anodized film formed on the surface of the base material, and photocatalyst fine particles and porous apatite provided on the outer periphery of the photocatalyst fine particles, A metal member comprising a large number of photocatalysts fixed to the anodized film. 10. The metal member according to claim 9, wherein the photocatalyst fine particles are titanium dioxide. 11. The base material is composed of a metal whose main component is magnesium.
Alternatively, the metal member according to claim 10.