JP2011021211A - Aluminum-based hydrophilic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member having excellent hydrophilicity and adhesiveness by treating a surface layer part of aluminum or its alloy by a simple chemical treatment. <P>SOLUTION: In an aluminum-based hydrophilic member, aluminum or its alloy is treated with a solution or a suspension liquid in which hydrophilic micro-particles are mixed in a basic mixed solution prepared by mixing alkali containing lithium hydroxide, water and organic solvent. thereby a porous network structure is formed as a carrier on at least a part of the surface layer part of aluminum or its alloy, and the hydrophilic micro-particles are carried by and fixed to the carrier. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydrophilic member made of a network-like porous structure formed on the surface of aluminum or an alloy thereof and subjected to a hydrophilic treatment.

  By imparting hydrophilicity to the surface of the metal, the affinity between the polar liquid such as water and the article is improved. Therefore, the hydrophilic member having the hydrophilic coating layer and the substrate is composed of a polar liquid such as water. It is used as an antifouling article utilizing the affinity, an anti-condensation article, an article with improved polarity liquid circulation, etc. Specific examples of these application fields include members for heat exchange elements such as heat pipes and fins.

In particular, as a method for improving the hydrophilicity with respect to an aluminum base material, a film forming process or a coating process is generally performed on the aluminum surface, and the following methods are known.
(1) A step of performing boehmite treatment in which an aluminum alloy is brought into contact with hot water or water vapor containing amines in the presence of a lithium salt (Patent Document 1).
(2) A method of forming a hydrophilic film by coating the aluminum surface with a solution containing an alkali silicate (alkali metal silicate), an inorganic curing agent, and a water-soluble organic polymer compound (Patent Document 2)
(3) A method for imparting hydrophilicity by immersing in the aqueous medium containing a compound having a silanol group and polyvinylpyrrolidone on the surface of a part made of aluminum (Patent Document 3)
(4) Applying a chromate treatment and then applying an aqueous solution of alkali silicate (alkali metal silicate) containing normal phosphoric acid, then applying a normal phosphoric acid solution, and then heating and drying to form a hydrophilic film Method (for example, Patent Document 4)
On the other hand, as a surface treatment method for forming a film by treating an aluminum surface with an alkali hydroxide containing lithium ions, a method of immersing an aluminum material in an aqueous solution of lithium nitrate and caustic soda (Patent Document 5), lithium ions and carbonate ions It discloses that a film is formed by a method (Patent Document 6) in which an aluminum surface is treated with an alkaline solution containing.

JP 52-9642 A JP-A-62-2235477 JP 62-272099 A JP-A-1-208475 JP-A-48-18131 JP 2005-8949 A

  The methods described in Patent Documents 2 and 4 give hydrophilicity using an alkali silicate (alkali metal silicate), but the adhesion is not always sufficient because it is physically attached to the member. That's not true. Moreover, when it is attempted to form a strong film of alkali silicate, it is necessary to process at a fairly high temperature of 400 ° C., so it is not an industrial technique, but when processed at a relatively low sound of about 120 ° C. to 150 ° C. Is not sufficiently cured, and when a hydrophilic coating derived from an alkali silicate is brought into contact with water for a long time, there may be a problem that the hydrophilic portion in the coating gradually disappears. Further, the method described in Patent Document 3 has a problem because sufficient hydrophilicity cannot be obtained. Furthermore, although the methods described in Patent Document 1, Patent Document 5 and Patent Document 6 describe that a film of hydrated aluminum oxide is obtained, it is known that the hydrophilicity of the film decreases with time. It has been.

  Therefore, there has been a demand for a member that imparts hydrophilicity to a member having pores formed by treating the surface layer portion of aluminum or an alloy thereof by simple chemical treatment, and is excellent in hydrophilicity and adhesion.

  In order to solve such problems, the present inventors have conducted intensive studies, and using a solution or suspension obtained by mixing “hydrophilic fine particles” with a “basic mixed solution containing lithium hydroxide”. By treating the aluminum-based material, hydrophilic fine particles are quickly supported from the side on which the network porous structure is formed, and hydrophilic particles are more firmly supported by a simple process. The present inventors have found that a member can be obtained and have reached the present invention.

  In addition, it is known to those skilled in the art that hydrophilic fine particles such as colloidal metal oxides and phyllosilicates react with alkali metal hydroxides, and there is a possibility of forming different forms of salts depending on the reaction. Mixing and suspending hydrophilic fine particles in a basic mixed solution containing lithium hydroxide is a process that is not normally performed.

That is, the present invention is as follows.
[Invention 1] Aluminum or an alloy thereof is treated with a solution or suspension obtained by mixing hydrophilic fine particles in a basic mixed solution obtained by mixing a base containing lithium hydroxide, water, and an organic solvent, thereby obtaining aluminum. Alternatively, an aluminum-based hydrophilic member, wherein a reticulated porous structure is formed on at least a part of a surface layer portion of the alloy, and the hydrophilic fine particles are supported and fixed on the reticulated porous structure.
[Invention 2] The aluminum-based hydrophilic member according to Invention 1, wherein the surface tension of the mixed solvent constituting the basic mixed solution is 18 to 60 mN / m.
“Invention 3” The organic solvent in the basic mixed solution is an alcohol, nitrile, ketone, ester, ether, sulfoxide, amide, glycol, aromatic, or fluorinated alcohol solvent. The aluminum-based hydrophilic member according to invention 1 or invention 2, which is at least one kind.
[Invention 4] The aluminum-based hydrophilic member according to Inventions 1 to 3, wherein the pH of the basic mixed solution is in the range of 9.0 to 13.5.
[Invention 5] The aluminum-based hydrophilic member according to Invention 1, wherein the network porous structure is a pore having a pore diameter of 5 to 500 nm and a depth of 0.05 to 10 [mu] m.
"Invention 6" The hydrophilic fine particles are colloidal silica, colloidal alumina, colloidal titanium, colloidal tin, colloidal antimony, colloidal mullite, colloidal iron, alumina, zeolite, silica gel, silica, alumina, titania, calcium carbonate, calcium oxide, talc, diatomaceous earth , Vermiculite, leechite, dials, shell calcined calcium fine particles, or gold, silver, platinum, palladium, ruthenium, copper, nickel, vanadium, titanium, indium, tin, tungsten nanometal particles or nanometal colloids The aluminum-based hydrophilic member according to invention 1, which is at least one selected from the group consisting of:
“Invention 7” The aluminum-based hydrophilic member according to Invention 1, wherein the hydrophilic fine particles are supported so that the weight of the hydrophilic fine particles is in the range of 0.1 to 20 g / m ² .

  The aluminum-based hydrophilic member of the present invention is industrially useful because a member in which hydrophilic particles are supported on a network porous structure can be obtained by a relatively simple method. In the hydrophilic member of the present invention, hydrophilic fine particles are rapidly supported from the side on which the mesh-like porous structure is formed, so that a hydrophilic member that is easy to manufacture and has excellent adhesion can be obtained. It is done. The hydrophilic member is useful as a member of a heat exchange element such as a heat pipe or a fin because it exhibits super hydrophilicity.

It is a SEM photograph of the aluminum plate (Example 1) which carry | supported the kaolinite microparticles | fine-particles in mesh-like porous.

  Next, the present invention will be described in detail.

  In the present invention, aluminum or an alloy thereof is treated with a solution or suspension obtained by mixing hydrophilic fine particles in a basic mixed solution obtained by mixing a base containing lithium hydroxide, water, and an organic solvent. Alternatively, the present invention relates to an aluminum-based hydrophilic member characterized in that a reticulated porous structure is formed as a carrier on at least a part of the surface layer portion of the alloy and the hydrophilic fine particles are supported and fixed on the carrier.

  In the present invention, the hydrophilic fine particles are rapidly supported on the uneven surface of the porous body or inside the porous voids while forming the network-like porous structure. In addition to being manufactured in the process, there is an effect that a hydrophilic member excellent in adhesiveness in which hydrophilic fine particles are more firmly supported is obtained.

  The aluminum-based material that is the subject of the present invention is pure aluminum having a purity of 99.9% or more and various aluminum alloys. Specific examples of the aluminum alloy include alloys containing a small amount of Si, Fe, Cu, Mn, Mg, etc., such as A1050, A1070, A1080, A1100, A1200, etc., and particularly A2014, A2017, A2024, etc. Alloys containing a large amount of Cu, alloys containing a particularly large amount of Mg such as A5052, A5083, A5154, alloys containing a particularly large amount of Zn such as A7075, A7N01, and alloys for casting containing a large amount of Si such as ADC12 There are various alloys.

  The aluminum-based material may be any shape. The present invention can be applied to any shape such as a plate shape, a line shape, a mesh shape, a curved surface shape, inner and outer surfaces of a pipe, a three-dimensionally processed part such as a block body and a heat exchange element. Also, as aluminum materials, aluminum foil, ingots, plates, pipes, aluminum fibers, die casts, intermediate products made of these aluminum materials, and finished products made of aluminum materials are all within the scope of the aluminum materials of the present invention. included.

  Among these, since the mesh-shaped thing has a large surface area, it is used suitably for uses, such as fins, such as a heat exchange element, and a hydrophilic film of a low-temperature humidifier. The mesh-like aluminum-based material can be obtained as an aluminum metal nonwoven fabric. The aluminum metal nonwoven fabric sheet is formed by rolling a sintered aluminum metal cotton sheet obtained by depositing aluminum metal fibers in a plate shape, and is complicatedly folded between the aluminum fibers. There is a feature that is large.

  Next, a “basic mixed solution in which a base containing lithium hydroxide, water, and an organic solvent are mixed” for forming a network-like porous structure in the aluminum material will be described.

  Here, the “solution” in the present invention means that the solute is completely dissolved in the solvent, and does not include those in which the solute is dispersed or suspended in the solvent. Moreover, when the said solvent is a mixed solvent of water and an organic solvent, a mixed solvent shall be uniform, without isolate | separating.

  In preparing at least “a basic mixed solution in which lithium hydroxide, water and an organic solvent are mixed”, it is desirable that a base such as lithium hydroxide is completely dissolved in the solute. The solvent in the basic mixed solution is a mixed solvent of water and an organic solvent, and a hydrophilic solvent described later is usually used as the organic solvent.

  By adjusting the surface tension of the mixed solvent, the wettability with the surface of the aluminum-based material is improved as will be described later, so that the reaction between the aluminum surface and lithium hydroxide proceeds promptly. Such surface tension is in the range of 18 to 60 mN / m, preferably 20 to 55 mN / m, and more preferably 20 to 50 mN / m. The surface tension of water is about 72 mN / m at 20 ° C., but the surface tension can be reduced by adding an organic solvent. If it is less than 18 mN / m, the wettability to the aluminum surface is excellent, but the water content becomes extremely small and lithium hydroxide does not dissolve, which is not preferable. Moreover, when surface tension becomes larger than 50 mN / m, since the wettability to the aluminum surface worsens, it is not preferable.

  In the mixed solvent constituting the basic mixed solution, there is no particular problem as long as it is within the range giving the above surface tension, but as a guideline for substantially preparing the mixed solvent, the mixing ratio of the organic solvent and water Is preferably (organic solvent / water) = (90/10) to (10/90), particularly preferably (70/30) to (30/70).

  If the basic mixed solution is (1) the solute is dissolved in the solvent, and (2) the surface tension of the mixed solvent constituting the basic mixed solution is within the above range, the preparation method is Although it does not specifically limit, Usually, after preparing the solution containing lithium hydroxide, the method of adding and preparing an organic solvent is used. As in the case of the basic mixed solution, the basic solution containing lithium hydroxide needs to dissolve a solute such as lithium hydroxide, and the solvent is “water alone” or “water and a hydrophilic organic solvent. “Mixed” is recommended.

That is, as a method for adjusting the basic mixed solution,
“1” A method for preparing a basic solution by dissolving a solute such as lithium hydroxide in water, and then adding a hydrophilic organic solvent. “2” A solute such as lithium hydroxide containing “water and hydrophilic organic”. A method of adding a solvent mixture and dissolving it to prepare a basic solution and then adding the same or another organic solvent can be mentioned. Usually, the method of “1” is preferably used.

  As the hydrophilic solvent, an alcohol, nitrile, ketone, ether, sulfoxide, amide, ester, or glycol solvent having 1 to 7 carbon atoms is preferably used. Examples of such a solvent include methanol, ethanol, isopropanol, acetonitrile, propylonitrile, acetone, methyl ethyl ketone, dimethyl ketone, methyl isobutyl ketone, dimethyl ether, diethyl ether, dioxane, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, dimethyl sulfoxide, dimethyl Examples include, but are not limited to, formamide, dimethylacetamide, methyl formate, ethyl formate, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, ethylene glycol, propylene glycol and the like. Among the above hydrophilic solvents, methanol and ethanol are particularly preferable because of availability. In addition, these solvents can be used 1 type or in mixture of 2 or more types.

  Next, an organic solvent is further mixed with the basic solution to prepare a basic mixed solution. However, it is important that a solute such as lithium hydroxide does not precipitate due to the mixing of the basic solution and the organic solvent. When the solvent of the basic solution is water alone, the hydrophilic solvent is preferably used as the organic solvent to be used.

  When the solvent of the basic solution is “mixture of water and a hydrophilic organic solvent”, the same kind or another hydrophilic organic solvent may be further added as the organic solvent from the hydrophilic organic solvent. Although it is good, for the purpose of further improving the wettability to the surface of the aluminum-based material, an aromatic solvent or a fluorine-containing alcohol solvent can be used. Such solvents include, but are not limited to, benzene, toluene, xylene, hexafluoroisopropyl alcohol, and the like. In addition, these solvents can be used 1 type or in mixture of 2 or more types.

  In order to perform an appropriate reaction, the pH of the mixed solution of the basic solution and the organic solvent is desirably in the range of pH 9.0 to pH 13.5. If the pH is less than 9.0, the reaction does not proceed. If the pH exceeds 13.5, the coating is vigorously eroded or the network porous structure is destroyed, which is not preferable.

  In the above mixed solution, the concentration of the solute that gives such pH depends on the difference in the solubility of a base such as lithium hydroxide in the mixed solvent constituting the basic mixed solution, and thus cannot be defined unconditionally. % By weight is preferred and 1.0 to 3.5% is particularly preferred. If the amount is less than 0.5% by weight, the reaction is insufficient. On the other hand, if the amount exceeds 5% by weight, the coating is vigorously eroded or the network porous structure is destroyed, which is not preferable.

When the mixed solution is an aqueous solution containing no organic solvent (surface tension: about 72 mN / m ² ), the surface of the aluminum-based material is water-repellent, resulting in poor wettability. In some cases, the basic solution is repelled. Therefore, a uniform reaction is difficult to proceed, which is not preferable. The reason why the surface of aluminum is water-repellent is considered to be due to the aluminum oxide film of several nm existing on the surface.

  In the preparation of the above mixed solution, as long as the pH is in the range of 9.0 to 13.5, an alkali metal salt or an alkaline earth metal salt can be further added as a solute in addition to lithium hydroxide. Examples of the alkali metal salt used include hydroxides such as sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Examples of the alkaline earth metal salt include hydroxides such as beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. Since alkali metal salts and alkaline earth metal salts differ in solubility in the solvent and base strength, they cannot be specified unconditionally, but the solute contained in the mixed solution is “lithium hydroxide and other alkali metal salts. The concentration of “lithium hydroxide and alkaline earth metal salt” is desirably at least 0.5% by mass of lithium hydroxide and “totally greater than 0.5 and not more than 5% by weight”. Within this range, the pH range is adjusted to 9.0 to 13.5 by appropriately adjusting the mixing ratio of “lithium hydroxide and other alkali metal salt” or “lithium hydroxide and alkaline earth metal salt”. Can be prepared. If the amount is less than 0.5% by weight, the reaction is insufficient. On the other hand, if the amount exceeds 5% by weight, the coating is vigorously eroded and micropores are destroyed. In particular, the concentration of the basic mixed solution is preferably 1 to 3.5%.

    About the preparation method in the case of adding and using another alkali metal salt or an alkali metal salt, it can carry out according to the case of lithium hydroxide alone.

  Next, the supported hydrophilic fine particles will be described.

  Examples of hydrophilic fine particles used include colloidal silica, colloidal alumina, colloidal titania, zeolite, silica gel, silica, alumina, titania, calcium carbonate, calcium oxide, talc, diatomaceous earth, balm curite, leechite, petite, Shell shell calcined calcium and phyllosilicate, metal fine particles and the like are raised, and at least one selected from these groups is preferably used. Among these particles, diatomaceous earth, zeolite, silica gel, shell calcined calcium and phyllosilicate can exhibit water absorption, antibacterial properties and the like due to their porous properties, and increase the added value of the article of the present invention. Can be used, and the use of calcined shell calcium and phyllosilicates is particularly preferred. These fine particles can be used in combination. For example, mica, which is a phyllosilicate, and silver particles of metal fine particles may be mixed.

  Shell shell calcined calcium has the effect of maintaining the hydrophilicity for a long time by increasing the surface adsorption of water because of its large specific surface area. In addition to its own calcium source, it is also used as a source of calcium, as a pesticide for pathogens, bacteria, etc., for cleaning residual agricultural chemicals in vegetables and fruit trees, and as a pharmaceutical product. The effect can be expected. Accordingly, when shell calcined calcium is introduced as fine particles, it is possible to add not only the maintenance of hydrophilicity but also an antibacterial function.

  Calcium shell calcium is calcium oxide (CaO) or calcium oxide and carbonic acid obtained by gradually decarboxylation (removing carbon dioxide) by firing shells whose main component is calcium carbonate before firing. It is a mixture of calcium. By firing, 99% of calcium carbonate, which is the main component before firing, is gradually converted to calcium oxide, and at the same time, firing of 1% of organic substances contained in the shell before firing also proceeds simultaneously. Regarding the firing temperature, when the firing temperature is increased, all of the calcium carbonate is converted to calcium oxide, but when the firing temperature is low, part of the calcium carbonate is changed to calcium oxide, but the rest remains as calcium carbonate.

  The component of the calcined shell shell calcium to be used is not particularly limited as long as a part of the calcium carbonate can be converted to calcium oxide. In the present invention, specifically, calcium carbonate as the main component of the shell and the calcined product thereof. It is preferable to use calcium oxide obtained by doing this, a mixture of calcium oxide and calcium carbonate, or a mixed state thereof (mixed calcium oxide and calcium carbonate). The proportions of calcium carbonate and calcium oxide and the respective components vary depending on the firing temperature and firing time, and can be adjusted as appropriate.

  The calcination temperature in the case of producing shell-calcined calcium is usually 500 to 1200 ° C. Preferably, it is a temperature range of 600-1100 degreeC. The firing time varies depending on the firing temperature, but can be appropriately adjusted in order to obtain the above-mentioned shell-fired calcium in a preferred ratio.

  The shell used as the shell calcined calcium is preferably a hydrophilic film in which at least one kind is selected from scallops, abalone, oysters, and oysters. Of course, the shell used in the present invention is not particularly limited as long as the component before baking contains calcium carbonate as a main component, and specifically, red shellfish, clams, scallops, abalone, oysters, basilis. (Sea bream), mussels, cherry mussels, turban shells, rainbow trout, snails, snails, tiger oysters, clams, snails, etc. are used. However, particularly preferred are scallop shells, abalone shells, oyster shells, and oyster shells.

  The phyllosilicate is characterized in that metal ions such as aluminum, sodium, calcium, and magnesium are linked with silicic acid to form a tetrahedral sheet layered structure. It is known that the interstices of the tetrahedral sheet layer structure have a property of exchanging metal ion organic substances and the like, and have a property of taking in water, and therefore exhibit extremely good hygroscopicity. Furthermore, improvement in capillary force, adhesion, and binding property can be expected due to the layered structure. That is, these new functions including improvement of hygroscopicity can be imparted by using phyllosilicate as fine particles.

  As phyllosilicate used in the present invention, mica, sepiolite, montmorillonite, halosite, kaolinite, smectite, talc, vermiculite, chlorite, gyrolite, branite, silicic peacock, stone pebbles, fisheye stone, talc Pyrophyllite, chlorite, dickite, serpentine, zeolite and the like. Among these phyllosilicates, mica, talc, and kaolinite are more preferable in consideration of the particle diameter, aspect ratio, availability, and cost.

There are various types of mica depending on the shape and size, and examples include muscovite, chrome muscovite, sericite, biotite, phlogopite, fluorine phlogopite, and lithia mica. Talc is also called talc and is a hydrate of magnesium silicate (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ). Kaolinite (Al ₂ Si ₂ O ₅ (OH) ₄ , triclinic / monoclinic) is a hydrate of aluminum silicate, but similar dictite and nakurite are also kaolin. To include.

  Examples of the metal fine particles include nano metal particles such as gold, silver, platinum, palladium, ruthenium, copper, nickel, vanadium, titanium, indium, tin, and tungsten, and nano metal colloids.

  The particle diameter of the fine particles is not particularly limited, but is preferably 5 nm to 50 μm. If the average particle size is less than 5 nm, the fine particles are too long and a long coating time is required and the efficiency is low. Also, the surface energy of the fine particles becomes very large, monodispersion is difficult, aggregation is easy, and handling is very difficult. is there. On the other hand, if the average particle size of the fine particles exceeds 50 μm, the influence of gravity increases because the particle size is much larger than the pore size of the mesh-like porous structure on the coating, and the fine particles incorporated in the pore size cannot be retained. The problem of peeling off easily due to friction occurs. More preferably, it is 0.5-40 micrometers, More preferably, it is 0.05-20 micrometers.

  Here, the particle size of the particles indicates the size of so-called primary particles, and does not indicate the size of secondary particles in which fine particles are aggregated. In the hydrophilic film, the size of the secondary particles is not particularly limited as long as there is no difficulty in film formation.

  The chemical solution for treating an aluminum material in the present invention is a solution or suspension (hereinafter referred to as “fine particle mixed solution”) obtained by mixing the basic mixed solution and the hydrophilic fine particles. The hydrophilic fine particles can be mixed as a hydrophilic sol. The mixing amount of the hydrophilic fine particles is not particularly limited as long as it can be favorably supported on the porous body on which the fine particles are formed, but 0.01% by weight to 20% by weight with respect to the basic mixing liquid is appropriate. . If it is less than 0.01% by weight, it is too dilute to be able to be fully supported, and if it is more than 20% by weight, the viscosity becomes too high and the operability is deteriorated, and the unsupported fine particles are increased and wasteful. It is.

  The prepared fine particle mixed solution desirably contains the hydrophilic fine particles contained therein uniformly in the basic mixed solution, and is preferably subjected to a treatment such as stirring or irradiation with ultrasonic waves.

  In the present invention, when the aluminum-based material is treated with the fine particle mixture, the aluminum-based material needs to be brought into contact with the fine particle mixture.

  As described above, since the surface of the aluminum-based material is water-repellent due to the aluminum oxide film, the removal of the film may be performed when the wettability with the chemical solution is poor. In general, surface activation treatment such as degreasing cleaning, sandpaper application, sandblasting, arc irradiation, plasma treatment, etc. is performed, but there are cases where uniform treatment is not possible due to unevenness during the surface activation treatment. In the production of the hydrophilic member of the present invention, the surface tension of the fine particle mixture is lowered by using an organic solvent, so that the smoothness with the aluminum surface is improved, so that it is uniform regardless of unevenness during the surface treatment. It is possible to react. Moreover, since the basic mixed solution containing lithium hydroxide has a certain degree of degreasing power, degreasing and surface activation treatment can be omitted by using the fine particle mixed solution.

  The method of bringing the aluminum-based material into contact with the fine particle mixed solution is not particularly limited, but the method of spraying the fine particle mixed solution with a spray or the like, the method of dropping with a syringe or the like, and immersion in a treatment bath of the fine particle mixed solution (including impregnation) ), But a method of immersing in a treatment bath is preferably used.

  The immersion (including impregnation) can be performed under normal pressure, reduced pressure, or increased pressure. In addition, an immersion ultrasonic method is also preferably used, and it is possible to immerse an aluminum material in a fine particle mixture and perform the treatment while applying ultrasonic waves.

  The immersion time in the treatment bath may be selected appropriately according to the type, shape, and dimensions of the aluminum-based material and the concentration, composition, bath temperature, etc. of the fine particle mixture, and is usually set to 30 seconds to 15 minutes. Is done. Further, the bath temperature may be set to an appropriate temperature in consideration of the immersion time. Usually, the fine particle mixed solution is set to about room temperature to about 50 ° C., and more preferably about 20 to 40 ° C. Set to When the temperature is lower than the above temperature range, the time required for the reaction to proceed is very long. On the other hand, when the temperature is high, the reaction becomes too fast, the coating is eroded violently, the mesh porous structure is destroyed, the surface Tends to be non-uniform.

  When the aluminum material is immersed, the reaction between aluminum and lithium hydroxide proceeds, and fine hydrogen foaming is observed from the surface of the aluminum material 30 seconds to 5 minutes after immersion. As a guide, moderate reaction can be performed by dipping for 30 seconds to 5 minutes after foaming.

  By treating the aluminum material with the fine particle mixed solution, the aluminum material and the basic mixing solution react to form a network-like porous structure having a pore diameter of 5 to 500 nm on the surface of the aluminum material. The hydrophilic fine particles are supported as anchors so as to fit the pore size of the porous structure, and have both strong adhesion because the hydrophilic fine particles and the porous structure adhere to each other. In this invention, since the said hydrophilic fine particle is carry | supported from the side in which the said porous body is formed, there exists an effect which is excellent in adhesiveness compared with the carrying | supporting fixation in two processes.

  Some of the inorganic fine particles used have a particle diameter larger than 500 nm, but a strong bond is formed between the outermost surface portion of the inorganic fine particles that have entered the hole as an anchor and the larger inorganic fine particles. Therefore, it is considered that the fine particles in the pores hold the particles outside the membrane, form a complex surface, and are covered with a coating having a large specific surface area. Since the coating is composed of hydrophilic fine particles, it exhibits excellent hydrophilicity and is useful as an aluminum-based hydrophilic composite member.

In the present invention, the weight per unit area of the supported hydrophilic fine particles needs to be in the range of 0.1 to 20 g / m ² . When the weight per unit area of the hydrophilic fine particles is less than 0.1 g / m ² , it is not preferable because sufficient coating is not performed and unevenness occurs in the coating. On the other hand, when the weight of the hydrophilic fine particles exceeds 20 g / m ² , the fine powder is coated on the front surface in the mesh-like porous material, and the mesh-like porous material is completely buried to reduce the surface area, so that the hydrophilic property is reduced. Not only is it inferior, but it is not economical, and it can be easily peeled off by friction and vibration, resulting in a significant hindrance to mechanical strength. After the above treatment, it can be formed into a film by drying and heating. It can be supported and fixed. The drying / heating treatment method is not particularly limited, and may be dried at room temperature or may be heated and dried with hot air. Further, a method of heating the aluminum base material to 100 to 500 ° C. after drying and further drying is also used. For example, a method of heating in an oven at 150 ° C. for about 1 hour after drying at room temperature for 30 minutes is used. In this way, an aluminum based composite hydrophilic member can be produced.

  When the surface of the aluminum-based hydrophilic member obtained by the treatment of the present invention was observed with a scanning electron microscope (hereinafter referred to as SEM), it was regularly arranged with a pore diameter of 5 to 500 nm and a depth of 0.05 to 10 μm. It was found that hydrophilic fine particles are supported in the pores of the mesh-like porous body.

  In the hydrophilic member of the present invention, the pure water contact angle is desirably 30 degrees or less. This is because if the pure water contact angle exceeds 30 degrees, the predetermined hydrophilicity cannot be obtained. More preferably, it is 20 degrees or less, and more preferably 10 degrees or less. Here, the following is used when the pure water contact angle is 30 degrees or less. For example, when the pure water contact angle is smaller than 5 degrees, high-precision measurement becomes difficult, but the pure water contact angle is extremely close to 0 °. This is because it also includes the case where the hydrophilicity of the resin is shown. In this specification, when a pure contact angle of 10 ° or less is exhibited, it is evaluated as “superhydrophilic”. The pure water contact angle is measured according to JIS R3257 “Test method for wettability of substrate glass surface”.

  When the pure water contact angle of the aluminum-based member having hydrophilic fine particles supported on the network porous structure of the present invention is measured, the water droplet spreads on the surface of the film, the contact angle cannot be measured, and the film is superhydrophilic. Can be observed.

Next, examples will be described together with comparative examples, but are not limited thereto. In the measurement, the following measuring devices were used.
"Scanning Electron Microscope" (Scanning Electron Microscope, SEM)
FE-SEM Hitachi S-4500 acceleration voltage 10kv
"Pure water contact angle measurement"
Kyowa Interface Science contact angle meter (model CA-X)
Measuring method: 5 μl of pure water is dropped on the surface and the contact angle is measured. “Example 1” Hydrophilic member: Aluminum plate
6.0 g (0.14 mol) of lithium hydroxide monohydrate (LiOH.H ₂ O: Wako Special Grade Reagent) was weighed into a 300 ml beaker, and then 100 ml of ion-exchanged water was added and stirred at room temperature to dissolve. Further, 100 ml of special grade ethanol was gradually added while stirring to prepare a 1.9% concentration lithium hydroxide treatment solution. The pH of the treatment solution was 11.1.

  10.0 g of kaolinite (manufactured by Takehara Chemical Co., Ltd.) having an average particle size of 0.5 μm as hydrophilic fine particles is added to the above basic mixing solution and dispersed for 20 minutes using a Suntech UX-300 type ultrasonic dispersion machine. Liquid.

A flat plate (100 mm × 50 mm × 0.1 mmt) of an aluminum base material: A1050 having a purity of 99.5% was immersed in this fine particle mixture while being ultrasonically vibrated at room temperature. Fine hydrogen foaming was observed from the surface of the aluminum substrate 30 seconds after the immersion. After dipping for about 1 minute, the film was pulled up at 4 mm / sec, then dried at room temperature for 30 minutes, and dried at 150 ° C. for 1 hour. Kaolinite was uniformly applied on the surface of aluminum, and the film weight was 4.1 g / m ² .

  When the contact angle of pure water was measured, the contact angle was 5.9 ° immediately after dropping, but within 2 seconds, the water droplet quickly spread on the surface of the coating and became so small that the contact angle could not be measured (contact for convenience) It was possible to observe that the coating was superhydrophilic. Further, after thoroughly washing the surface with clean water for 3 minutes, drying at 100 ° C. for 1 hour and measuring the pure water contact angle again, the pure water contact angle was 0 ° and no change in hydrophilicity was observed. When the surface was observed with an SEM, the porous body and hydrophilic fine particles were sufficiently supported even before and after washing, and the film was robust.

"Example 2"
A hydrophilic member was produced in the same manner as in Example 1 except that colloidal silica was used as the hydrophilic fine particles.

  10 g of colloidal silica (IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) having an average particle size of 0.05 μm as hydrophilic fine particles was added to the basic mixed solution prepared in the same manner as in Example 1, and Suntech UX-300 type ultrasonic dispersion machine was used. For 20 minutes to prepare a white milk-colored fine particle mixture.

A flat plate (100 mm × 50 mm × 0.1 mmt) of an aluminum base material: A1050 having a purity of 99.5% was immersed in this fine particle mixture while being ultrasonically vibrated at room temperature. Fine hydrogen foaming was observed from the surface of the aluminum substrate 30 seconds after the immersion. After being immersed for about 1 minute, it was pulled up at 4 mm / sec, then dried at room temperature for 30 minutes, and dried at 150 ° C. for 1 hour. According to SEM observation, 50% of the voids in the aluminum porous body were filled with colloidal silica. Although the supported amount decreased by 42% compared to the conventional method treated in the two-step process, the hydrophilicity was not changed at all and the pure water contact angle was 4.5 degrees. Although the amount of hydrophilic fine particles supported is reduced by half in the one-step process, the post-process (cutting and bending process) of the hydrophilic-treated aluminum substrate was superior in coating strength. This is presumably because the hydrophilic fine particles were applied following the uneven coating.
"Example 3"
A hydrophilic member was produced in the same manner as in Example 1 except that calcined shell calcium was used as the hydrophilic fine particles.

  To the basic mixed solution prepared in the same manner as in Example 1, 10 g of calcined shell calcium (made of Japan natural material) having an average particle size of 5 μm as hydrophilic fine particles was added, and 5 ml of 0.1% PVA solution was added. A fine particle mixture was prepared by dispersing for 20 minutes using a UX-300 type ultrasonic dispersing machine.

  A flat plate (100 mm × 50 mm × 0.1 mmt) of an aluminum base material: A1050 having a purity of 99.5% was immersed in this fine particle mixture while being ultrasonically vibrated at room temperature. Fine hydrogen foaming was observed from the surface of the aluminum substrate 30 seconds after the immersion. After being immersed for about 1 minute, it was pulled up at 4 mm / sec, then dried at room temperature for 30 minutes, and dried at 150 ° C. for 1 hour. According to SEM observation, some fine baked shell particles are filled in the voids of the porous body of aluminum, and the coarse particles of 3 to 10 microns are fixed to the recesses of the porous body by the anchor effect. The contact angle also showed a hydrophilicity of 8.2 degrees. Also in the post-processing of the substrate (cutting and bending processing), the coating did not peel off and was excellent in durability.

The hydrophilic member is useful as a member of a heat exchange element such as a heat pipe or a fin because it exhibits super hydrophilicity.

Claims (7)

By treating aluminum or an alloy thereof with a solution or suspension obtained by mixing hydrophilic fine particles in a basic mixed solution obtained by mixing a base containing lithium hydroxide, water and an organic solvent, the aluminum or the alloy thereof is treated. An aluminum-based hydrophilic member, wherein a reticulated porous structure is formed on at least a part of a surface layer portion as a carrier, and the hydrophilic fine particles are supported and fixed on the carrier. The aluminum-based hydrophilic member according to claim 1, wherein the mixed solvent constituting the basic mixed solution has a surface tension of 18 to 60 mN / m. The organic solvent in the basic mixed solution is at least one of an alcohol, nitrile, ketone, ester, ether, sulfoxide, amide, glycol, aromatic, or fluorinated alcohol solvent. The aluminum-based hydrophilic member according to claim 1 or 2. 4. The aluminum-based hydrophilic member according to claim 1, wherein the pH of the basic mixed solution is in a range of 9.0 to 13.5. The aluminum-based hydrophilic member according to claim 1, wherein the network-like porous structure is a pore having a pore diameter of 5 to 500 nm and a depth of 0.05 to 10 µm. Hydrophilic fine particles are colloidal silica, colloidal alumina, colloidal titania, zeolite, silica gel, silica, alumina, titania, calcium carbonate, calcium oxide, talc, diatomaceous earth, balm curite, leechite, petal, shell calcined calcium fine particles Or at least one selected from the group consisting of nanometal particles or nanometal colloids of gold, silver, platinum, palladium, ruthenium, copper, nickel, vanadium, titanium, indium, tin, and tungsten. Aluminum-based hydrophilic member. The aluminum-based hydrophilic member according to claim 1, wherein the hydrophilic fine particles are supported so that the weight of the hydrophilic fine particles is in the range of 0.1 to 20 g / m ² .