JP2000204283A - Surface treatment composition for aluminum heat- exchanger fin material, and surface treatment process thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment composition which is suitable for antibacterial/ fungicidal treatment, hydrophilization treatment or deodorizing treatment of aluminum heat- exchanger fin material surfaces, shows a high adhesion against aluminum substrates and corrosion resistance and shows a high antibacterial/fungicidal property, hydrophilic property and odor component-decomposing property by irradiation with ultraviolet rays, a surface treatment process of aluminum heat-exchanger fin materials using this composition and an aluminum heat-exchanger fin material coated with this composition. SOLUTION: The surface treatment composition for aluminum heat-exchanger fin materials is prepared by blending, to an inorganic coating composition (I), obtained by mixing (A) a polyorganosiloxane having a repetitive structural unit of the formula: RaSiO(4-a)/2 (wherein R is a monovalent (non)substituted hydrocarbon group; and a is from 0.8 to 1.8) and 1 wt.% or more silicon atom-bound hydroxyl groups, (B) a hydrolyzable organosilane compound of the formula: R'bSiX(4-b) (wherein each R' is an identical or different monovalent (non) substituted 1-8C hydrocarbon group; b is an integer of from 0 to 3; and X is a hydrolyzable group) or hydrolysate thereof, (C) a hydrophilic organic solvent, (D) water and (E) a metal chelate compound and/or metal alcoholate, (F) from 20 to 300 pts.wt., in a solid content ratio against 100 pts.wt. inorganic coating composition, titanium oxide having a photocatalytic effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is suitable for antibacterial / antifungal treatment, hydrophilization treatment and deodorization treatment of the surface of an aluminum heat exchanger fin material, has excellent adhesion to an aluminum substrate, excellent corrosion resistance, Surface treatment composition showing excellent antibacterial / antifungal property, hydrophilicity, decomposition of odor components by irradiation, surface treatment method of aluminum heat exchanger fin material using the composition, and applying the composition To a heat exchanger fin material made of aluminum.

[0002]

2. Description of the Related Art When a titanium oxide having a photocatalytic action is irradiated with light having a wavelength having energy equal to or greater than its band gap, electrons are accumulated in a conduction band and holes are generated in a valence band. It is well known that organic substances are decomposed by a strong redox effect caused by electrons and holes generated by photoexcitation.

[0003] Attempts to utilize the photocatalytic action of this titanium oxide industrially have been widely carried out, and in particular, efforts are being made in antifouling, antibacterial, air purification and water purification. Many have been made.

In a heat exchanger of an air conditioner, condensed water generated during cooling becomes water droplets to form a water bridge between fins, and a ventilation resistance increases to narrow an air ventilation path. Problems such as generation of noise and scattering of water droplets occur. As a measure for preventing such a phenomenon, the surface of aluminum fins (hereinafter abbreviated as "fins") is made hydrophilic to prevent water droplets and the formation of bridges due to the water droplets.

[0005] As a method for performing the surface hydrophilization treatment of such a heat exchanger, (1) an aluminum plate is formed and formed into fins, and after assembling the fins, a surface treatment material is dipped, sprayed, showered or the like. A so-called after-coating method of applying by a coating means, and (2) applying a surface treatment material to an aluminum plate in advance by a roll coater or the like to form a surface treatment film, and then press-forming the aluminum plate to produce fins So-called pre-coat method 2
There are two ways.

In the after-coating method (1),
Examples of the method for making the surface of the fin hydrophilic include (a) a method of applying a water glass represented by the general formula mSiO ₂ / nNa ₂ O (for example, JP-A-59-13078).
(B) a method of applying a solution mainly composed of an organic polymer resin such as a water-soluble polyamide resin to form a resin film (for example, JP-A-61-250495, etc.), (c)
A method of applying a coating composed of an organic-inorganic (silica) composite resin and a surfactant (for example, JP-A-59-17017)
Although some of these methods have already been put to practical use, they are not sufficiently satisfactory, and the method has a long-lasting hydrophilic property (water droplet contact angle, total surface area, etc.). There are still issues to be improved in terms of water wettability), corrosion resistance, odor, and stability of the processing solution.

For example, regarding the method of using the water glass of the above (a), which shows good hydrophilicity persistence such that the contact angle of a water droplet is 20 degrees or less, the fins treated with this material exhibit a powdery form on the treated film over time. This powdery substance is scattered during ventilation to generate a cement odor or a chemical odor.
Further, water glass is hydrolyzed by condensed water generated during operation of the heat exchanger, and the fin surface becomes alkaline, so that pitting corrosion is likely to occur. On the other hand, in the method using the treatment agent of the above (b), the water resistance of the film is not sufficient, and the film is easily dissolved by condensed water, so that the hydrophilicity of the fin surface and the corrosion resistance are reduced. There is.

In the precoating method (2), if silica, alumina, aluminum hydroxide, calcium carbonate, etc. are mixed in the surface treatment film layer, the mold used for press molding wears out and the fins are worn. Poor molding of the material,
Problems such as deterioration of corrosion resistance due to destruction of the surface treatment film occur. In addition, the press forming method has also changed from the conventional draw processing method (overhanging and drawing) to a more stringent drawless processing method (ironing processing). Can't handle it.

Further, recently, since a comfortable living space has been demanded, generation of odor by the air conditioner has been regarded as a problem. As a countermeasure against the smell of the coating film at the beginning of use and the unpleasant odor at the start of operation due to microorganisms generated in the air conditioner, use of a treating agent mixed with an antibacterial agent and an antifungal agent has been proposed (Japanese Patent Application Laid-Open No. 58-1983). No. 10051, JP-A-61-16
No. 8675), but the effect is insufficient, and it is not a preferable method from the viewpoint of health and safety such as human body and environment.

[0010] As described above, the methods currently put into practical use do not sufficiently meet such demands, are more excellent in hydrophilicity and corrosion resistance, have no problem of odor, and have no problem in the human body.
Development of a surface treatment composition for an aluminum heat exchanger fin material which is harmless to the environment and has excellent antibacterial and antifungal properties and a method of treating the surface are desired.

[0011]

SUMMARY OF THE INVENTION The present invention provides a photocatalytic titanium oxide immobilized on an aluminum heat exchanger fin using a hard-to-decompose inorganic coating composition having excellent adhesion and durability as a binder. The present invention provides a surface treatment composition for a heat exchanger fin material made of aluminum and a method for treating the surface thereof.

[0012]

Means for Solving the Problems The present inventors co-condensate a hydroxyl group-containing polyorganosiloxane with a hydrolyzable organic silane compound or a hydrolyzate thereof to adhere tightly to an aluminum substrate and to copolymerize the same. Titanium oxide having photocatalytic action is immobilized on the substrate using the substance as a binder, and the surface is irradiated with ultraviolet light having a wavelength of 400 nm or less, whereby organic substances on the substrate surface are decomposed, and excellent antibacterial and antifungal properties are obtained. It has been found that high deodorizing and long-lasting water wettability can be obtained. In addition, the present inventors have found that a similar excellent effect can be obtained by immobilizing titanium oxide having a photocatalytic action on an aluminum substrate using a condensate of a hydrolyzable organic silane compound as a binder. It was completed.

Thus, according to the present invention, (A) the general formula R _a SiO _{(4-a) / 2} (wherein R represents a monovalent substituted or unsubstituted hydrocarbon group, and a represents 0. A polyorganosiloxane having a repeating structural unit represented by the following formula (1) and having at least 1% by weight of a hydroxyl group bonded to a silicon atom: (B) a polyorganosiloxane represented by the general formula _: R'bSix _(4-b) (In the formula, R ′ represents the same or different monovalent substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms, b represents an integer of 0 to 3, and X represents a hydrolyzable group.) Inorganic coating obtained by mixing a hydrolyzable organic silane compound or a hydrolyzate thereof, (C) a hydrophilic organic solvent, (D) water, and (E) a metal chelate compound and / or metal alcoholate To the composition (I), (F) titanium oxide having a photocatalytic action is added to the inorganic coating in a solid content ratio. Composition 1
A surface treatment composition for an aluminum heat exchanger fin material, characterized in that the composition is 20 to 300 parts by weight based on 00 parts by weight.

According to the present invention, there is also provided (B) a compound represented by the following general formula: R ′ _b SiX _{(4-b) wherein} R ′ is the same or different and is a monovalent substituted or unsubstituted C 1-8 carbon atom. Represents a hydrocarbon group, b represents an integer of 0 to 3, and X represents a hydrolyzable group.) Or a hydrolyzate thereof, (C) a hydrophilic organic solvent, D) water and (E) an inorganic coating composition (II) obtained by mixing a metal chelate compound and / or a metal alcoholate with (F) titanium oxide having a photocatalytic action in a solid content ratio of inorganic coating composition A surface treatment composition for an aluminum heat exchanger fin material characterized by being blended in an amount of 20 to 300 parts by weight with respect to 100 parts by weight of the composition.

According to the present invention, there is also provided a method for treating the surface of an aluminum heat exchanger fin material, which comprises applying the surface treatment composition to an aluminum heat exchanger fin material.

According to the present invention, there is also provided an aluminum heat exchanger fin material coated with the above-mentioned surface treatment composition.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

Inorganic Coating Composition (I) The polyorganosiloxane (A) used in the inorganic coating composition (I) of the present invention is preferably resinous from the viewpoint of film forming properties. R in the above is an organic group having 1 to 8 carbon atoms, preferably an alkyl group such as methyl, ethyl and propyl; an aryl group such as phenyl; and a haloalkyl group such as chloromethyl. A in the polyorganosiloxane is 0.8
To 1.8, preferably 1.0 to 1.6, and if it is less than 0.8, the storage stability is poor.
Gelation is likely to occur, while if it exceeds 1.8, the curing rate is low, so that the resulting film has poor curability and does not show sufficient solvent resistance.

The polyorganosiloxane of the component (A)
It has a number average molecular weight of 1,000 to 30,000 and has a hydroxyl group of 1% by weight or more, preferably 3% by weight or more. If it is less than 1% by weight, the curability becomes insufficient,
Solvent resistance cannot be obtained.

In the component (B) used in the inorganic coating composition (I) of the present invention, R ′ in the hydrolyzable organic silane compound represented by the general formula R ′ _b Six _(4-b) is a carbon atom. Represents a substituted or unsubstituted monovalent hydrocarbon group represented by Formulas 1 to 8, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; an aryl group such as a phenyl group; a cyclopentyl group or a cyclohexyl group A vinyl group, chloromethyl group, γ-chloropropyl group, 3,3,3-trifluoropropyl group, γ
-Methacryloxypropyl group, γ-glycidoxypropyl group, mercaptopropyl group, 3,4-epoxycyclohexylmethyl group, γ-aminopropyl group and the like.

As the hydrolyzable group X, an alkoxy group,
Examples thereof include an acetoxy group, an oxime group, and an aminoxy group, and an alkoxy group is preferable in terms of availability.

A monofunctional compound wherein b in the formula is an integer of 0 to 3,
Specific examples of bifunctional, trifunctional, and tetrafunctional alkoxysilanes include, when b = 0, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and the like. b
= 1, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxy Silane, γ
-Glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltri Ethoxysilane, γ-aminopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane and the like can be mentioned. When b = 2, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, γ-
Glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-amino Propylmethyldiethoxysilane and the like can be mentioned.
When b = 3, trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane,
Dimethylisobutylmethoxysilane and the like can be exemplified.

Among the above alkoxysilanes, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, γ-glycidoxypropyl Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ
-Mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like are preferred. These alkoxysilanes can be used alone or in combination of two or more.

The ratio of the component (B) to the component (A) is such that the hydroxyl group in the polyorganosiloxane of the component (A) is 1
0.2 to 10 equivalents, preferably 0.5 to
It is 8.0 equivalents. If it is less than 0.2 equivalent, the low-temperature curability is poor, and the adhesion is also reduced. If it exceeds 10 equivalents, the film is liable to crack at the time of thick film, and the continuous film forming property is reduced.
The kind of the hydrophilic organic solvent of the component (C) is methanol, ethanol, isopropyl alcohol, n-butanol,
Alcohols such as isobutanol; ethylene glycol derivatives such as ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol tert-butyl ether, and ethylene glycol monoethyl ether; propylene glycol monomethyl ether and propylene glycol monomethyl ether Propylene glycol derivatives such as pionate; other diethylene glycol derivatives and diacetone alcohol; and one or more selected from these can be used. In combination with these hydrophilic organic solvents, ethyl acetate, butyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene and the like can be used.

The amount of the component (C) used is such that the solid content concentration of the polyorganosiloxane of the component (A) is 20 to 50% by weight,
Preferably, the amount is 30 to 40% by weight. If it exceeds 50% by weight, the storage stability of the solution is poor, and if it is less than 20% by weight, the degree of freedom of the composition of the diluting solvent at the time of coating is narrowed, which may hinder the coating.

Next, regarding the water as the component (D),
0.2 to 2 equivalents, preferably 0.5 to 1.5 equivalents, per equivalent of alkoxyl group contained in the organic silane compound of the component.
Used in equivalent proportions. If it exceeds 2 equivalents, the storage stability of the reaction composition deteriorates, and if it is less than 0.2 equivalent,
Hydrolysis of the organic silane compound becomes insufficient and sufficient curability cannot be obtained.

Next, the metal chelate compound of the component (E) includes aluminum acetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum-di-n-butoxide-monoethylacetoacetate, and aluminum-di-isopropoxide. Aluminum chelate compounds such as monomethyl acetoacetate; titanium chelate compounds such as titanium acetylacetonate and titanium tetraacetylacetonate;
In addition, chromium acetylacetonate, cobalt acetylacetonate, tin acetylacetonate, iron (II
I) acetylacetonate, manganese acetylacetonate, nickel acetylacetonate and the like. Examples of metal alcoholates include tetraisopropyl titanate, tetra-n-butyl titanate, tetra-2-ethylhexyl titanate, tetraethoxyzirconium, tetrapropoxyzirconium, tetraisopropoxyzirconium, tetrabutoxyzirconium, triethoxyaluminum, and triisopropoxy. Aluminum and the like can be mentioned. These metal chelate compounds and metal alcoholates can be used alone or in combination of two or more.

Component (E) is used in an amount of 0.01 to 1 based on 100 parts by weight of the total of components (A) and (B).
0 parts by weight, preferably 0.1 to 5 parts by weight. 0.0
If the amount is less than 1 part by weight, the curability is reduced, and the solvent resistance cannot be obtained. If the amount exceeds 10 parts by weight, storage stability and weather resistance may decrease, and coloring such as yellowing of the film may occur.

In order to obtain the inorganic coating composition (I) of the present invention, it is necessary to hydrolyze the organosilane compound as the component (B). In this case, the purpose is to promote the hydrolysis reaction. An inorganic acid and an organic acid such as hydrochloric acid, acetic acid, chloroacetic acid, citric acid, formic acid, propionic acid, oxalic acid, and maleic acid can be used as the catalyst. The hydrolysis reaction temperature is room temperature, preferably 40 ° C. or higher, more preferably 50 to 80 ° C., and the reaction time is 0.5 to 3 hours, preferably 1 to 2 hours.

The component (E) can be mixed with the components (A) to (D) in a lump and added with the above-mentioned hydrolysis catalyst, if necessary, and preferably mixed in advance. The components (A) to (D) are mixed and heat-treated at 40 ° C. or higher, and after hydrolyzing the organosilane compound of the component (B), the component (E) is added and the mixture is further heated at 40 ° C. or higher. By performing the treatment, the self-condensation of the component (A) or the component (B) is suppressed, the formation of a microgel which causes the occurrence of lumps in the film is suppressed, and the hydroxyl group-containing polyorganosiloxane of the component (A) and (B) A) A co-condensation product with the component organosilane compound can be obtained.

By co-condensing the hydroxyl group-containing polyorganosiloxane (A) and the organic silane compound (B), the fineness of the organic silane compound is reduced to a dense polyorganosiloxane having a high continuous film-forming property. And low-temperature curability.

The thus obtained inorganic coating composition (I) of the present invention hardly causes cracks,
At a relatively low temperature of 0 ° C. or less, a cured film having excellent curability, adhesion, and durability is formed, and is hardly affected by humidity during curing.

Inorganic coating composition (II) The components (B) to (E) used in the inorganic coating composition (II) of the present invention are exactly the same as those described for the inorganic coating composition (I).

The amount of component (C) used is such that the solid concentration of the organosilane compound of component (B) is 20 to 50% by weight, preferably 30 to 40% by weight. If it exceeds 50% by weight, the storage stability of the solution is poor, and if it is less than 20% by weight, the degree of freedom of the composition of the diluting solvent at the time of coating is narrowed, which may hinder the coating.

The amount of water used as the component (D) is 0.2 to 2 equivalents, preferably 0.5 to 1.5 equivalents, per equivalent of the alkoxyl group contained in the organosilane compound as the component (B). Used in proportions used. If it exceeds 2 equivalents, the storage stability of the reaction composition will be poor. If it is less than 0.2 equivalent, the hydrolysis of the organic silane compound will be insufficient and sufficient curability will not be obtained.

Component (E) is used in an amount of (B) 100
0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per part by weight.
1 to 5 parts by weight. If the amount is less than 0.01 part by weight, the curability is reduced and the solvent resistance cannot be obtained. If the amount exceeds 10 parts by weight, storage stability and weather resistance may decrease, and coloring such as yellowing of the film may occur.

The component (E) can be mixed with the components (B) to (D) at a time, and can be mixed by adding the above-mentioned hydrolysis catalyst, if necessary. The components (B) to (D) are mixed and heat-treated at 40 ° C. or higher, and after hydrolyzing the organosilane compound as the component (B), the component (E) is added and the mixture is further heated at 40 ° C. or higher. By performing the treatment, the self-condensation of the component (B) is suppressed,
It is possible to suppress the formation of microgels that cause the occurrence of bumps in the film, and to obtain a (co) condensation product of the organosilane compound as the component (B).

The thus obtained inorganic coating composition (II) of the present invention hardly causes cracks,
At a relatively low temperature of 50 ° C. or lower, a cured film having excellent curability, adhesion, and durability is formed, and hardly affected by humidity during curing.

In order to impart a function such as antibacterial / antifungal, deodorizing, or wet with water to the surface of an aluminum substrate using the above-mentioned inorganic coating composition (I) or (II), oxidation having a photocatalytic action is required. Utilizes the organic substance resolution of titanium fine particles.

The crystal form of titanium oxide may be anatase type or rutile type, but anatase type titanium oxide is preferable from the viewpoint of photocatalysis. Also, the surface of titanium oxide is silica,
Those coated with alumina and zirconium oxide can also be used.

In the coating agent containing titanium oxide, the mixing ratio of the film-forming component and titanium oxide is 20 to 30 as a solid content with respect to 100 parts by weight of the film-forming component.
0 parts by weight, preferably 50 to 200 parts by weight. 20
If the amount is less than part by weight, the photocatalytic action of titanium oxide is reduced, and the practicality is poor in terms of functions such as antibacterial / antifungal, deodorizing, and water wettability. If the amount exceeds 300 parts by weight, the adhesive strength with the base material is reduced, the abrasion resistance is reduced, and the material tends to fall off.

In order to obtain a cured film at a lower temperature and in a shorter time, an amine, an organic metal salt, an organic acid, and the like may be used in addition to the metal chelate compound and the metal alkoxide. Alternatively, among curing catalysts such as anhydrides, Lewis acids, and metal halide compounds, those which do not impair the storage stability of the surface treatment composition may be used in combination with the surface treatment composition. Furthermore, coloring pigments, extender pigments, glitters, dyes, etc. can be blended according to the necessity of design, and thickeners, defoaming agents, leveling agents,
An anti-bake agent and the like can also be blended, and for the purpose of improving film performance, ultraviolet absorbers, light stabilizers, etc., as well as storage stabilizers, pH
Adjusters and the like can also be blended.

The method for surface-treating an aluminum heat exchanger fin using the surface-treating composition of the present invention by the after-coating method is as follows. First, the surface-treating composition is appropriately adjusted to a concentration suitable as a surface-treating agent for the heat exchanger fin. Adjust and apply conventional painting methods, such as dip painting, shower painting, spray painting,
The coating is performed by applying the heat exchanger fins by roll coating or the like, followed by heating and drying.

Of the above surface treatment methods, dip coating is particularly preferred. When the surface treatment is performed by such dip coating method, the solid concentration of the surface treatment composition is usually 0.2 to 0.2.
The heat exchanger fins pre-molded and assembled are immersed in an immersion bath adjusted to a range of 20% by weight, preferably 0.5 to 10% by weight, pulled up, and then baked under appropriate baking conditions, for example, 80 to 80% by weight. It can be performed by baking at 200 ° C. for 10 to 30 minutes.

The surface treatment method of the aluminum heat exchanger fin using the surface treatment composition of the present invention by the precoating method is as follows. First, the surface treatment composition is appropriately adjusted to a concentration suitable as a surface treatment agent for the heat exchanger fin. Then, it is performed by applying to a molded heat exchanger fin by a conventional coating method, for example, dip coating, shower coating, spray coating, roll coating, and the like, and then heating and drying. In general, the maximum temperature at which the material reaches is 80 to 250 ° C.
The baking time is 30 minutes to 15 seconds.

The surface-treated film thus formed has a dry thickness of 0.01 to 10 μm, preferably 0.05 to 5 μm.
m. When the film thickness is less than 0.01 μm, the functions such as antibacterial and antifungal, deodorizing, water wettability are insufficient,
If it exceeds 10 μm, there is a possibility that the heat radiation efficiency of the heat exchanger fins after the molding process is reduced.

When a condensation product consisting of only an organic silane compound is used as a binder for titanium oxide, it is important that the thickness of the film be 3 μm or less in order to prevent the occurrence of cracks. Care must be taken when using a tetrafunctional silane such as tetraethoxysilane in an equivalent number exceeding 70% of the equivalent number of the organic silane compound, since cracks tend to occur in the film.

Next, by irradiating the film formed by the above-mentioned surface treatment method with ultraviolet rays, antibacterial / antifungal, deodorizing and water wettability can be obtained. As the ultraviolet irradiation device, any device including a wavelength of 400 nm or less may be used.
Ultraviolet lamps such as black light can be used, but among them, cold cathode fluorescent lamps utilizing glow discharge are desirable, and since they do not use a filament, they have a long lamp life and are generally small, so the lamp replacement frequency is low. This is preferable from the viewpoint of miniaturization of the heat exchanger.

[0049]

The surface treatment composition and the surface treatment method for an aluminum heat exchanger fin material according to the present invention are provided by co-condensing a hydroxyl-containing polyorganosiloxane with a hydrolyzable organic silane compound or a hydrolyzate thereof. ,
Adhesion and low-temperature curability of organic silane compounds can be imparted to polyorganosiloxane, which has a high ability to form a dense continuous film. Maintains continuous molding processability by directly applying to aluminum fin materials. In addition, it shows excellent corrosion resistance, and it is possible to omit the chromate treatment and chemical conversion treatment of aluminum to secure the corrosion resistance, which is a conventional technology, and it is industrially extremely useful from the viewpoint of no pollution and a great reduction in man-hours. is there.

Further, by adding titanium oxide having a photocatalytic action to the inorganic coating composition, it is possible to fix titanium oxide on the aluminum fin material. It is possible to obtain the antibacterial and antifungal properties, the decomposition of odorous components, and the long-lasting water wettability, which was a problem of the prior art.

[0051]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. “Parts” and “%” in the description are based on weight.

Production Example of Inorganic Coating Composition (A) Production Example 1 2 equipped with a reflux condenser, stirrer, thermometer and dropping funnel
In a 4-liter four-neck flask, add 450 parts of isobutanol.
Parts, isopropyl alcohol 230 parts, dimethyl-type polyorganosiloxane having a hydroxyl group content of 6% and a molecular weight of 3,200, 283 parts, tetraethoxysilane 42
And 132 parts of γ-glycidoxypropylmethyldimethoxysilane were added thereto, and 36 parts of a 0.01 N hydrochloric acid aqueous solution was added dropwise with stirring. Then, the mixture was heated at 60 ° C. for 1 hour while maintaining the liquid temperature, and then aluminum was added. 4 parts of acetylacetonate was added, and the mixture was further heated at 60 ° C. for 1 hour. The solid concentration of the obtained inorganic coating composition (A-1) was 39.
8% and the viscosity was 102 cps. The solid content was calculated by heating the sample at 120 ° C. for 30 minutes and measuring the remaining amount. The viscosity was measured at 60 rpm with a B-type viscometer.
The value at the time of m is shown.

Production Example 2 A 2 equipped with a reflux condenser, a stirrer, a thermometer and a dropping funnel was prepared.
In a liter four-necked flask, add isobutanol 420
Parts, 460 parts of isopropyl alcohol, 340 parts of a dimethyl-type polyorganosiloxane having a hydroxyl group content of 5% and a molecular weight of 3,700 and 248 parts of γ-glycidoxypropylmethyldiethoxysilane, and 0.1 g of the mixture was stirred. After dropwise addition of 36 parts of a 01N hydrochloric acid aqueous solution, the mixture was heated for 1 hour while maintaining the liquid temperature at 40 ° C. Then, 4 parts of aluminum acetylacetonate was added, and the mixture was further heated at 60 ° C. for 1 hour. The obtained inorganic coating composition (A-
2) The solid concentration is 40.2% and the viscosity is 140 c
ps.

Production Example 3 (Hydrolysis of organosilane compound only)
Dissolution and condensation products) 2 equipped with a reflux condenser, stirrer, thermometer and dropping funnel
After adding 460 parts of isopropyl alcohol, 186 parts of tetraethoxysilane and 192 parts of γ-glycidoxypropyltrimethoxysilane to a four-necked flask of a little and adding 108 parts of 0.01N hydrochloric acid aqueous solution with stirring, The solution was heated for 1 hour while maintaining the liquid temperature at 0 ° C, then 7.5 parts of aluminum acetylacetonate was added, and the mixture was further heated at 60 ° C for 1 hour. The solid content concentration of the obtained inorganic coating composition (A-3) was 29.2%,
The viscosity was 75 cps.

Production Example 4 (for comparison, polyorganosiloxa)
2) equipped with a reflux condenser, stirrer, thermometer and dropping funnel
In a four-necked liter flask, add 284 isobutanol.
Parts, 142 parts of isopropyl alcohol and 283 parts of a dimethyl-type polyorganosiloxane having a hydroxyl group content of 6% and a molecular weight of 3,200, and 1.4 parts of aluminum acetylacetonate under stirring.
Heated for hours. The obtained inorganic coating composition (A-
4) The solid concentration is 37.3%, and the viscosity is 220c.
ps.

Production Example of Titanium Oxide-Containing Surface Treatment Solution (B) Production Example 5 The inorganic coating composition (A-1) obtained in Production Example 1 was
"ST-K03" (product of Ishihara Sangyo Co., Ltd., anatase type titanium oxide sol, titanium oxide content: 5%) was mixed. The mixing ratio is the solid content ratio of the inorganic coating composition 1
The amount of titanium oxide was 100 parts with respect to 00 parts. The mixture was further diluted with isobutanol to obtain a titanium oxide-containing surface treatment liquid (B-1) having a solid content of 5%.

Production Example 6 The inorganic coating composition (A-12) obtained in Production Example 2 was charged with "Optreike 1130Z" (a product of Kako Kasei Kogyo Co., Ltd., rutile-type titanium oxide sol, titanium oxide content: 30).
%, Silica / zirconia treatment, hereinafter abbreviated as "1130Z"). The mixing ratio was 100 parts of titanium oxide sol with respect to 100 parts of the inorganic coating composition in terms of solid content. The mixture was further diluted with isobutanol to obtain a titanium oxide-containing surface treatment solution (B) having a solid content of 5%.
-2) was obtained.

Production Example 7 The inorganic coating composition (A-3) obtained in Production Example 3 was added to
"ST-K03" was mixed. The mixing ratio was 1 part of titanium oxide to 100 parts of the inorganic coating composition in a solid content ratio.
00 parts. The mixture was further diluted with isobutanol to obtain a titanium oxide-containing surface treatment solution (B) having a solid content of 2%.
-3) was obtained.

Production Examples 8 to 13 In the same manner as in Production Example 5, the types and amounts of the inorganic coating composition and the titanium oxide sol were changed, and the solid content concentration was 5% at the blending amount (solid content) shown in Table 3. (B-2) to (B-9) were obtained. In addition, (B
Regarding -6), the solid concentration was set to 2%.

[0060]

[Table 1]

Example 1 An untreated aluminum plate having a thickness of 0.1 mm (A-105)
Dip coating was carried out in the titanium oxide-containing surface treatment solution (B-1) obtained in Production Example 5 so as to have a dry film thickness of 0.5 to 1 μm, and dried at 120 ° C. for 30 minutes. To form a film. Thereafter, irradiation was performed with two black lights from a distance of 5 cm above the film. At that time, the ultraviolet intensity on the film surface was 1 mW / cm ² at a wavelength of 365 nm.

Examples 2 to 6 and Comparative Examples 1 to 3 Films were formed on the same aluminum plates as in Example 1 by using the surface treatment liquids obtained in Production Examples 6 to 13 in the same manner as in Example 1. Formed and irradiated with ultraviolet light. The performance test results of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 2 below.

Example 7 An untreated aluminum plate having a thickness of 0.1 mm (A-105)
0) as an object to be coated, in a titanium oxide-containing surface treatment solution (B-1) obtained in Production Example 5 so as to have a dry film thickness of 0.5 to 1 μm, and reach the material with hot air at 220 ° C. Temperature 2
The film was baked at 15 ° C. for 30 seconds to form a film. Thereafter, irradiation was performed with two black lights from a distance of 5 cm above the film. The UV intensity on the film surface at that time was 3
It was 1 mW / cm ² at a wavelength of 65 nm.

Examples 7 to 12 and Comparative Examples 4 to 6 A film was formed on the same aluminum plate as in Example 7 by using the surface treating solution obtained in Production Examples 6 to 13 in the same manner as in Example 7. Formed and irradiated with ultraviolet light. Table 3 shows the performance test results of Examples 7 to 12 and Comparative Examples 4 to 6.

The test method of the performance test in Tables 2 and 3 is as follows.

Adhesion: After irradiating with a black light for 12 hours, a 1 mm square goban eye test (cellotape peeling)
Was evaluated according to the following criteria.

：: no peeling at all, Δ: peeling within 1/5 in 100 cells, ×: peeling 1/3 or more in 100 cells.

Water wettability: After irradiating with a black light for 12 hours, the test plate was immersed in tap water for 30 seconds, and the water wettability when pulled up was evaluated according to the following criteria.

：: Water wet area ratio 100%, ：: Water wet area ratio 90 or more and less than 100%, Δ: Water wet area ratio 50 or more to less than 90%, ×: Water wet area ratio less than 50%.

Corrosion resistance: After irradiating with black light for 12 hours, the area ratio of white rust generation on a flat portion after 500 hours of JIS Z-2371 salt spray test was evaluated according to the following criteria.

◎: White rust occurrence area ratio of less than 1%, ：: White rust occurrence area ratio of 1% to less than 10%, Δ: White rust occurrence area ratio of 10% to less than 30%, ×: White rust occurrence area Rate is 30% or more.

Antibacterial and antifungal properties: A mixed spore suspension of a test bacterium consisting of Aspergillus, Penicillium, Alternaria and Cladosporium was sprayed on a coated plate in accordance with JIS Z-2911, and the mixture was sprayed at 27 ° C. After being kept at the temperature for 20 days, it was irradiated with black light for 6 hours, and the generation and adhesion of bacteria on the coated plate surface were evaluated according to the following criteria.

：: No generation or adhesion of bacteria was observed on the painted surface. Δ: Bacteria generation or adhesion was observed on less than 1/3 of the painted surface. ×: Generation of bacteria was observed on 1/3 or more of the painted surface.・ Adhesion is observed.

[0074]

[Table 2]

[0075]

[Table 3]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 183/04 C09D 183/04 F28F 1/32 F28F 1/32 G (72) Inventor Katsumi Mitsuishi Hiratsuka, Kanagawa 4-17-1, Higashi-Yawata, Kansai F-term (reference) in Kansai Paint Co., Ltd. 4D075 CA13 CA34 CA37 CA45 DB07 DC16 EB43 4J038 AA011 DL021 DL022 DL051 HA216 HA441 JA23 JC38 KA04 MA07 PB06 PC02

Claims (4)

[Claims] (A) A compound represented by the general formula: R _a SiO _{(4-a) / 2} (wherein R represents a monovalent substituted or unsubstituted hydrocarbon group, and a is 0.8 to 1.8) (B) a polyorganosiloxane having a repeating unit represented by the following formula (1) and having at least 1% by weight of a hydroxyl group bonded to a silicon atom: (B) a general formula R ′ _b SiX _(4-b) Represents the same or different monovalent substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms, b represents an integer of 0 to 3, and X represents a hydrolyzable group. (C) hydrophilic organic solvent, (D) water, and (E) an inorganic coating composition (I) obtained by mixing a metal chelate compound and / or a metal alcoholate. , (F) titanium oxide having a photocatalytic action in a solid content ratio of inorganic coating composition 1
20. A surface treatment composition for a heat exchanger fin material made of aluminum, which is blended in an amount of 20 to 300 parts by weight with respect to 00 parts by weight. (B) a compound represented by the following general formula: R ′ _b SiX _{(4-b) wherein} R ′ is the same or different and is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms; b represents an integer of 0 to 3, and X represents a hydrolyzable group.) or a hydrolyzable organic silane compound represented by the formula (C): a hydrophilic organic solvent; (D) water; E) The inorganic coating composition (II) obtained by mixing the metal chelate compound and / or the metal alcoholate is mixed with (F) titanium oxide having a photocatalytic action in a solid content ratio of 100 parts by weight of the inorganic coating composition. A surface treatment composition for a heat exchanger fin material made of aluminum, which is blended in an amount of 20 to 300 parts by weight. 3. A method for surface treating an aluminum heat exchanger fin material, comprising applying the surface treatment composition according to claim 1 or 2 to an aluminum heat exchanger fin material. 4. An aluminum heat exchanger fin material coated with the surface treatment composition according to claim 1 or 2.