Surface treatment agent for aluminum-containing metal materials

Abstract

To provide a surface treatment agent for aluminum-containing metal materials capable for forming a coating that has excellent anticorrosive and drainage properties and is rendered less odorous.SOLUTION: A surface treatment agent for aluminum-containing metal materials comprises: a resin (A) having an ethylene structural unit and a hydroxyethylene structural unit; an ether compound (B) having an epoxy group and / or a hydroxyl group; and a metal compound (C), where the content of the ethylene structural unit in the resin (A) is 1-20 mol%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a surface treatment agent for an aluminium-containing metallic material, a method for producing a surface-treated metallic material using the surface treatment agent, an aluminium-containing metallic material having a surface treatment film, and a heat exchanger. [Background technology]

[0002] Conventionally, heat exchangers used in air conditioners for buildings and automobiles are often made of aluminum-containing metal materials due to their superior workability and thermal conductivity. To maximize heat exchange efficiency, the spacing between the aluminum-containing metal materials (commonly called fins) in the ventilation area is designed to be very narrow. When an air conditioner is operating (cooling), moisture in the air condenses on the fins, forming condensation. The more hydrophobic the fin surface, the more bulky the condensed water becomes, making it more susceptible to clogging between the fins. Clogging increases ventilation resistance, reduces heat exchange efficiency, and prevents the heat exchanger from achieving its full performance. Clogging can also increase noise during ventilation. To address these issues, methods have been proposed and implemented to impart hydrophilic properties to aluminum-containing metal materials.

[0003] For example, Patent Document 1 (JP 2016-222920 A) describes an aqueous resin dispersion with excellent dispersion stability, which contains EVOH (A) and a radical polymer (B) having structural units derived from a radically polymerizable carboxylic acid monomer (B1-1), and the content of the radical polymer (B) is 10 to 80 mass% based on the total amount of the EVOH (A) and the radical polymer (B). Patent Document 1 also describes that a hydrophilic treatment agent containing this aqueous resin dispersion is preferably used for metals, particularly aluminum and its alloys, and is capable of forming a hydrophilic coating that is excellent in hydrophilicity, particularly in the persistence of hydrophilicity after contamination has adhered, and that also has excellent adhesion, drainage, and contamination removal properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-222920 Summary of the Invention [Problem to be solved by the invention]

[0005] Although the aqueous resin dispersion described in Patent Document 1 is said to have excellent dispersion stability, the inventors' investigations have shown that a hydrophilic film formed using a hydrophilic treatment agent containing this aqueous resin dispersion was unable to achieve sufficient performance in terms of corrosion resistance, drainage, and odor suppression in more stringent tests that took into account the actual operating conditions of air conditioners.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide, in one embodiment, a surface treatment agent for aluminum-containing metal materials that is capable of forming a coating that has excellent corrosion resistance and drainage properties and that has reduced odor. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that blending the following resin (A), ether compound (B), and metal compound (C) is advantageous for obtaining a surface treatment agent for aluminum-containing metal materials that is capable of forming a coating that is excellent in corrosion resistance and drainage properties and has suppressed odor, and have thus completed the present invention.

[0008] The present invention is exemplarily specified as follows. [1] A surface treatment agent for aluminum-containing metal materials, comprising a resin (A) having an ethylene structural unit and a hydroxyethylene structural unit, an ether compound (B) having either an epoxy group or a hydroxyl group, or both, and a metal compound (C), wherein the content of the ethylene structural unit in the resin (A) is 1 to 20 mol %. [2] The masses of the resin (A), the ether compound (B), and the metal compound (C) contained in the surface treatment agent are respectively represented by MA , M B and M C Expressed as M A / (M B +M C )=0.1 to 3.0. [3] The masses of the ether compound (B) and the metal compound (C) contained in the surface treatment agent are respectively M B and M C Expressed as M B / M C The surface treatment agent according to [1] or [2], which is formulated so as to satisfy the relationship of .gtoreq.0.1 to 3.0. [4] The surface treatment agent according to any one of [1] to [3], wherein the metal compound (C) is an oxide containing silicon. [5] A method for producing a surface-treated metal material, comprising the steps of: contacting the surface treatment agent according to any one of [1] to [4] with the surface or on the surface of an aluminum-containing metal material; and drying the surface treatment agent after the contacting step. [6] An aluminum-containing metal material having a surface treatment film formed by contacting the surface treatment agent according to any one of [1] to [4] on or above the surface. [7] A heat exchanger comprising the aluminum-containing metal material according to [6]. [Effects of the Invention]

[0009] According to one embodiment of the present invention, a surface treatment agent for an aluminium-containing metal material can be provided that is capable of forming a coating that has excellent corrosion resistance and drainage properties and suppresses odor. Therefore, the present invention can contribute to improving the performance of, for example, heat exchangers that include an aluminium-containing metal material, particularly air conditioners that include an aluminium-containing metal material as fins. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention, including a surface treatment agent and a surface-treated metal material, will be described in detail. The present invention can be modified as desired without departing from the spirit of the present invention, and is not limited to the following embodiments. In this specification, the symbol "to" indicating a numerical range includes both the upper and lower limits. For example, "X to Y" means that the range is from X to Y.

[0011] <1. Surface treatment agent> According to one embodiment of the present invention, there is provided a surface treatment agent for aluminum-containing metal materials, which comprises a resin (A) having an ethylene structural unit and a hydroxyethylene structural unit, an ether compound (B) having either an epoxy group or a hydroxyl group, or both, and a metal compound (C), wherein the content of the ethylene structural unit in the resin (A) is 1 to 20 mol %.

[0012] [1-1. Resin (A)] Resin (A) has ethylene structural units and hydroxyethylene structural units. Resin (A) is a type of ethylene-vinyl alcohol copolymer (hereinafter referred to as "EVOH"), and the content of ethylene structural units is 1 to 20 mol %, thereby ensuring water solubility. Water solubility provides the advantage of improved workability. Resin (A) may be used alone or in combination of two or more. The lower limit of the content of ethylene structural units in resin (A) is preferably 3 mol % or more, more preferably 5 mol % or more. The upper limit of the content of ethylene structural units in resin (A) is preferably 17 mol % or less, more preferably 14 mol % or less. Therefore, the content of ethylene structural units in resin (A) is preferably, for example, 3 to 17 mol %, more preferably 5 to 14 mol %.

[0013] The content of ethylene structural units in resin (A) (also called the "ethylene modification rate") can be measured by proton NMR. The specific measurement procedure is as follows: Resin (A) is added to deionized water and heated to 85-95°C to dissolve. This is then diluted with dimethyl sulfoxide (DMSO)-d6 so that the concentration of resin (A) becomes 1.0 mass% to prepare an NMR sample. Proton NMR measurement is performed using a nuclear magnetic resonance analyzer (e.g., JNM-EX400: JEOL Ltd.). The measurement is performed under the following conditions: Measured nuclide: 1H Observed temperature: 25.1℃ The peaks in the obtained spectrum are assigned as follows: 1.0 to 2.0 ppm: methylene protons of ethylene structural units and methylene protons of hydroxyethylene structural units 3.7 to 4.1 ppm: methine protons of hydroxyethylene structural units adjacent to at least one ethylene structural unit 4.1 to 4.5 ppm: methine protons of hydroxyethylene structural units that are not adjacent to ethylene structural units According to the above attribution, when the integral value from 1.0 to 2.0 ppm is x, the integral value from 3.7 to 4.1 ppm is y, and the integral value from 4.1 to 4.5 ppm is z, the ethylene modification rate can be calculated by the following formula. Ethylene modification rate = {(x-2y-2z) / 4} / {y+z+(x-2y-2z) / 4}

[0014] The upper limit of the weight average molecular weight of resin (A) is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 50,000 or less. The lower limit of the weight average molecular weight of resin (A) is preferably 1,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. Therefore, the weight average molecular weight of resin (A) is, for example, preferably 1,000 to 100,000, more preferably 5,000 to 80,000, and even more preferably 10,000 to 50,000. The weight average molecular weight of resin (A) can be measured by GPC.

[0015] The lower limit of the saponification degree of the resin (A) is preferably 90 mol% or more, more preferably 95 mol% or more. There is no particular upper limit to the saponification degree of the resin (A), and it may be 100 mol%. The saponification degree of the resin (A) is measured in accordance with JIS K6726-1994.

[0016] Resin (A) can be produced according to a known EVOH production method, and is not particularly limited. For example, a method can be used in which ethylene and a vinyl ester are radically polymerized in a predetermined molar ratio to obtain an ethylene-vinyl ester copolymer, which is then saponified. Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, and vinyl caproate. Among these, vinyl acetate is preferred.

[0017] [1-2. Ether Compounds (B)] The ether compound (B) has either an epoxy group or a hydroxyl group, or both. The ether compound (B) functions as a binder and can improve the durability of the coating by preventing the resin (A) from washing away. Examples of the ether compound (B) include, but are not limited to, polyalkylene glycols, polyalkylene glycol alkyl ethers, carbohydrates having a pyranose structure or a furanose structure, glycidoxy group-containing silane compounds, and glycidyl ether compounds. The ether compound (B) may be used alone or in combination of two or more.

[0018] Examples of polyalkylene glycols include polyethylene glycol and polypropylene glycol. Examples of polyalkylene glycol alkyl ethers include polyethylene glycol (mono)methyl ether, poly(ethylene, propylene) glycol (mono)methyl ether, and polyethylene glycol (mono)ethyl ether.

[0019] Carbohydrates having a pyranose or furanose structure include polysaccharides such as starch, glycogen, cellulose, chitin, and dextran, as well as derivatives thereof. Examples of polysaccharide derivatives include cellulose derivatives, such as alkyl celluloses (e.g., methyl cellulose (MC)), hydroxyalkyl celluloses (e.g., hydroxypropyl cellulose (HPC) and hydroxyethyl cellulose (HEC), hydroxyalkyl alkyl celluloses (e.g., hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEMC), and hydroxyethyl ethyl cellulose (HEEC), and sodium carboxymethyl cellulose (CMC-Na).

[0020] Examples of glycidoxy group-containing silane compounds include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylethyldiethoxysilane, 3-glycidoxypropyldiethylethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0021] Examples of glycidyl ether compounds include sorbitol polyglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, ethylene oxide-containing phenolic glycidyl ether, ethylene oxide-containing lauryl alcohol glycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD type epoxy resin.

[0022] [1-3. Metal compound (C)] The metal compound (C) acts as an inhibitor that suppresses the progression of corrosion in various environments, and its inclusion in the coating makes it possible to ensure excellent corrosion resistance over a long period of time. Examples of such metal compounds (C) include compounds containing at least one metal selected from Si, Ti, V, Cr, Mn, Co, Zn, Zr, Mo, Ce, and W. Among these, compounds containing at least one metal selected from Si, Ti, V, and Zr are preferred, with silicon compounds being more preferred. The metal compound (C) can take the form of an oxide, hydroxide, fluoride, chloride, carbonate, nitrate, sulfate, acetate, phosphate, organic acid salt, or the like, and is not particularly limited in type. In this specification, Si is also considered a metal. The metal compounds (C) may be used alone or in combination of two or more.

[0023] Examples of silicon compounds include silicon dioxide and its hydrates, silicates, and silicon-containing oxides such as organoalkoxysilanes. Silicon dioxide can be suitably used in the form of fumed silica (also called "gas-phase silica"), which is prepared by vaporizing silicon chloride and synthesizing silica fine particles through a gas-phase reaction in a high-temperature hydrogen flame. Silicon dioxide can also be suitably used in the form of colloidal silica, which is prepared by reacting silicate with dilute hydrochloric acid and then dialysis. Examples of silicates include those represented by M2O·nSiO2 (n is 1 to 8, and M represents Na, K, Li, or NH4). Organoalkoxysilanes contain alkoxysilane groups that hydrolyze upon contact with water to form silanol groups (Si—OH), which then crosslink to form siloxane compounds.

[0024] Examples of titanium compounds include titanium oxide, titanium hydrofluoric acid and its salts (potassium, ammonium salts, etc.), titanium sulfate and its salts (potassium, ammonium salts, etc.), titanyl sulfate, titanium acetylacetonate, titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine.

[0025] Examples of vanadium compounds include vanadium pentoxide, metavanadates (sodium, potassium, ammonium salts, etc.), vanadium pentafluoride, vanadyl sulfate, vanadium acetylacetonate, and vanadyl acetylacetonate.

[0026] Examples of chromium compounds include chromium oxide, dichromic acid and its salts (sodium, potassium, ammonium salts, etc.), chromium fluoride, chromium carbonate, chromium nitrate, chromium sulfate, chromium phosphate, chromium biphosphate, and chromium acetylacetonate.

[0027] Examples of manganese compounds include manganese oxide, manganates (sodium and potassium salts, etc.), permanganate and its salts (sodium, potassium, calcium, barium, lithium salts, etc.), manganese carbonate, manganese nitrate, manganese phosphate, manganese hydrogen phosphate, and manganese acetylacetonate.

[0028] Examples of cobalt compounds include cobalt oxide, cobalt hydroxide, cobalt carbonate, cobalt nitrate, cobalt sulfate and its salts (potassium, ammonium salts, etc.), cobalt phosphate, cobalt pyrophosphate, and cobalt acetylacetonate.

[0029] Examples of zinc compounds include zinc oxide, zinc hydroxide, zinc carbonate, zinc nitrate, zinc sulfate and its salts (potassium and ammonium salts, etc.), zinc phosphate, zinc hydrogen phosphate, zinc acetylacetonate, and the like.

[0030] Examples of zirconium compounds include zirconium oxide, zirconium hydroxide, zirconium hydrofluoride and its salts (potassium, ammonium salts, etc.), zirconium oxychloride, zirconium hydroxychloride, ammonium zirconium carbonate, potassium zirconium carbonate, zirconium sulfate, zirconium nitrate, zirconium acetate, zirconium phosphate, sodium zirconium phosphate, zirconium propionate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium tetraacetylacetonate, zirconium acetylacetonate bisethylacetoacetate, zirconium acetate, zirconyl stearate, and zirconyl octoate.

[0031] Examples of molybdenum compounds include molybdenum oxide, molybdic acid and its salts (sodium, potassium, magnesium, ammonium salts, etc.), and molybdenyl acetylacetonate.

[0032] Examples of cerium compounds include cerium oxide, cerium hydroxide, cerium chloride, cerium carbonate, ceric sulfate and its ammonium salt, cerium nitrate, ammonium ceric nitrate, cerium acetate, cerium phosphate, cerium octoate, and cerium acetylacetonate.

[0033] Examples of tungsten compounds include tungsten oxide, tungstic acid and its salts (sodium, potassium, magnesium, ammonium salts, etc.).

[0034] Also usable are composite compounds of the above metals, such as zinc dichromate, zinc permanganate, cobalt tungstate, cerium tungstate, and pigments which are mixtures of oxides.

[0035] [1-4. Blending ratio of resin (A), ether compound (B) and metal compound (C)] The masses of the resin (A), ether compound (B), and metal compound (C) contained in the surface treatment agent are respectively M A , MB and M C The resin (A), the ether compound (B) and the metal compound (C) are represented by M A / (M B +M C ) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. In addition, the resin (A), the ether compound (B), and the metal compound (C) are preferably mixed so that M A / (M B +M C ) is preferably blended so that it is 3.0 or less, more preferably 2.0 or less, and even more preferably 1.0 or less. Therefore, the resin (A), the ether compound (B), and the metal compound (C) are blended so that it is, for example, M A / (M B +M C It is preferable to mix them so that the relationship of M ) = 0.1 to 3.0 is satisfied, A / (M B +M C It is more preferable to mix them so that the relationship of M ) = 0.2 to 2.0 is satisfied. A / (M B +M C It is even more preferable to compound them so that the relationship of )=0.3 to 1.0 holds.

[0036] The masses of the ether compound (B) and metal compound (C) contained in the surface treatment agent are respectively M B and M C The ether compound (B) and the metal compound (C) are represented by M B / M C It is preferable to mix them so that the ratio of M to M is 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. B / M CIt is preferable to blend them so that the ratio is 3.0 or less, more preferably 2.0 or less, and even more preferably 1.0 or less. Therefore, the ether compound (B) and the metal compound (C) are blended so that the ratio is, for example, M B / M C It is preferable to blend so that the relationship of M = 0.1 to 3.0 is satisfied. B / M C It is more preferable to mix them so that the relationship of M = 0.2 to 2.0 is satisfied. B / M C It is even more preferable to blend them so that the relationship of .gtoreq.0.3 to 1.0 holds.

[0037] [1-5. Other ingredients] The surface treatment agent may contain various additives, such as antibacterial agents, lubricants, surfactants, pigments, dyes, and inhibitors for imparting corrosion resistance, as needed. Furthermore, the surface treatment agent preferably contains water or a mixed solvent of water and a water-miscible solvent to dissolve the resin (A). From the viewpoint of ease of handling the surface treatment agent, it is preferable to use deionized water as the water. The water content is preferably 80 to 99 mass%, more preferably 85 to 95 mass%, based on the total amount of the surface treatment agent. When a mixed solvent of water and a water-miscible solvent is used, the proportion of water is preferably, for example, 60 mass% or more based on the total mass of the mixed solvent. The water-miscible solvent is not particularly limited as long as it does not undergo phase separation after mixing with water, and examples thereof include alcohols such as methanol and ethanol.

[0038] [1-6. Manufacturing Method] The surface treatment agent can be prepared, for example, by mixing the above components in a desired ratio, adding a required amount of water to the mixture, and stirring.

[0039] <2. Surface-treated metal materials> According to one embodiment of the present invention, there is provided a method for producing a surface-treated metal material, comprising the steps of contacting the surface treatment agent with the surface or on the surface of an aluminum-containing metal material and drying the surface treatment agent after the contacting step. This method also produces an aluminum-containing metal material having a surface treatment film. The proportions of resin (A), ether compound (B), and metal compound (C) in this surface treatment film are substantially the same as those of resin (A), ether compound (B), and metal compound (C) in the surface treatment agent. The aluminum-containing metal material having a surface treatment film produced in this manner is useful for forming fin materials. This fin material is also useful as a heat exchanger component.

[0040] [2-1. Aluminum-containing metal materials] The material constituting the aluminum-containing metallic material may be pure aluminum, or may be an aluminum alloy.

[0041] [2-2. Cleaning process] It is preferable to preliminarily clean untreated aluminum-containing metal materials with an acidic or alkaline cleaner. Examples of acidic cleaners include an acidic aqueous solution containing at least one of nitric acid, sulfuric acid, and hydrofluoric acid. Examples of alkaline cleaners include an alkaline aqueous solution containing at least one of sodium hydroxide, sodium silicate, and sodium phosphate. To improve cleaning properties, a surfactant may be added to the alkaline aqueous solution. Examples of cleaning methods for aluminum-containing metal materials include immersion and spraying.

[0042] [2-3. Rust prevention treatment] Rust prevention treatment may be performed after the cleaning process. Rust prevention treatment methods include chemical conversion treatment and base rust prevention treatment using a resin primer. Among these, the chemical conversion treatment agent used in the chemical conversion treatment includes a conventionally known chromate chromate treatment agent, a phosphate chromate treatment agent, or a non-chromium treatment agent. The resin primer can include a conventionally known water-soluble or water-dispersible aqueous resin. Rust prevention treatment methods for aluminum-containing metal materials include, for example, an immersion method and a spray method.

[0043] [2-4. Contact process] The method for contacting the surface treatment agent with the surface or on the surface of the aluminum-containing metal material is not particularly limited, but examples include immersion, spraying, roll coating, brush coating, etc. The temperature of the surface treatment agent at this time can be about 10 to 50°C. The contact time can be about 3 seconds to 5 minutes.

[0044] [2-5. Drying process] The method for drying the surface treatment agent is not particularly limited as long as the water in the surface treatment agent evaporates. Examples include drying methods using known drying equipment, such as ovens, batch-type drying ovens, continuous hot air circulation drying ovens, conveyor-type hot air drying ovens, and electromagnetic induction heating ovens using IH heaters. The drying temperature can be 100 to 250°C, preferably 120 to 180°C. The drying time can be 10 seconds to 120 minutes, preferably 1 to 60 minutes.

[0045] [2-6. Mass of surface treatment film] The mass of the surface treatment film on the aluminum-containing metal material having the surface treatment film is not particularly limited as long as it is an amount that can exhibit the effects of the present invention. 2 The amount is preferably within the range of 0.01 to 5.0 g per unit, more preferably within the range of 0.05 to 3.5 g, and particularly preferably within the range of 0.1 to 2.0 g.

[0046] (Post-processing process) A post-treatment step may be carried out after the formation of the surface treatment film. Examples of the post-treatment step include a lubricating oil contact step or a lubricating film formation step. More specifically, a step of contacting a lubricating oil or a lubricant with the surface treatment film on the surface of the aluminum-containing metal material to form a lubricating film can be mentioned. In this way, an aluminum-containing metal material having a multi-layer film can be obtained in which a lubricating oil is contacted or a lubricating film is formed on the surface treatment film. The method for contacting the lubricating oil or lubricant is not particularly limited, and examples thereof include a roll coating method, a spray method, and an immersion method.

[0047] As the lubricating oil, any known lubricant used in molding processes can be used, and as the lubricant for forming the lubricating film, known lubricants such as water-soluble polyether, polyethylene glycol, polyoxyethylene alkyl ether, and polyoxyethylene hydrogenated castor oil ether can be used. [Example]

[0048] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0049] <Production of Resin (A)> [Synthesis Example 1] A 2L autoclave reactor equipped with a reflux condenser, raw material inlet, thermometer, nitrogen inlet, and stirring blade was charged with 25 g of vinyl acetate and 120 g of methanol while introducing nitrogen gas. 25 ml of a 2% methanol solution of 2,2'-azobis(2,4-dimethylvaleronitrile) as an initiator was added in small portions. The ethylene pressure inside the autoclave was adjusted to 0.7 MPa, and the polymerization reaction was initiated at 60 °C. After 5 hours of reaction, unreacted vinyl acetate was removed under reduced pressure to prepare an ethylene vinyl acetate resin methanol solution. A 10% aqueous sodium hydroxide solution was added to the resulting ethylene vinyl acetate resin methanol solution so that the molar ratio of sodium hydroxide to vinyl acetate (25 g) used as the raw material was 0.01, and the mixture was saponified at 50 °C for 1 hour. The methanol was then distilled off under reduced pressure, and the water was removed by centrifugation. After drying, a powder of ethylene-vinyl alcohol copolymer (resin (A)) with a degree of saponification of 98% was obtained. 5 g of the obtained powder was placed in 95 g of warm water at 85 to 95°C and heated with stirring for 2 to 3 hours, after which it was completely dissolved. The ethylene modification rate of the obtained powder was measured by proton NMR and found to be 10 mol %. The weight average molecular weight was measured by gel permeation chromatography (GPC) and found to be 9000. Each analysis was carried out under the following conditions. 1) Proton NMR The obtained sample was added to deionized water and heated to 85-95°C to dissolve. This was then diluted with dimethyl sulfoxide (DMSO)-d6 to a resin (A) concentration of 1.0 mass% to prepare an NMR sample. Proton NMR measurements were performed using a nuclear magnetic resonance analyzer (JNM-EX400: JEOL Ltd.). The measurement conditions and the calculation method for the ethylene modification rate were as described above. 2) GPC Measurement was carried out using a high-speed GPC device (HLC-8320GPC: manufactured by Tosoh Corporation), and the weight-average molecular weight was determined using a combination of an SEC column and a guard column. The measurement was carried out under the following conditions. SEC column: TSKgel SuperAWM-H (Tosoh Corporation) Guard column: TSK guard column SuperAW-H (manufactured by Tosoh Corporation) Detector: RI (built-in detector in HLC-8320GPC) Standard sample: polystyrene Sample injection volume: 30 μL of 0.06% DMF solution Flow rate: 0.5mL / min Eluent: DMF / 100mM LiBr / 60mM H3PO4

[0050] [Synthesis Examples 2 to 8] Resin (A) was synthesized in exactly the same manner as in Synthesis Example 1, except for the conditions shown in Table 1. The ethylene modification rate, molecular weight, and degree of saponification of the obtained resin (A) are shown in Table 2. The obtained resins (A) are referred to as A1, A2, A3, etc., corresponding to the numbers of the synthesis examples. 5 g of each of the obtained resins A1 to A6 was added to 95 g of warm water at 85 to 95°C and heated and stirred for 2 to 3 hours, and all of them dissolved. Resins A7 and A8 did not dissolve using the method described above.

[0051] [Synthesis Example 9] Resin (A) was synthesized in exactly the same manner as in Synthesis Example 1, except for the conditions shown in Table 1. Nitrogen (0.1 MPa) was used as pressure during polymerization instead of ethylene. The ethylene modification rate, molecular weight, and degree of saponification of the obtained resin (A) are shown in Table 2. Five grams of each of the obtained resins A9 were added to 95 g of warm water at 85 to 95°C and heated and stirred for 2 to 3 hours, whereupon they were completely dissolved.

[0052] [Table 1]

[0053] <Preparation of surface treatment agent> Tables 2 to 4 show the raw materials used in the surface treatment agents of the Examples and Comparative Examples. Table 2 lists the resins (A) used in the Examples and Comparative Examples. Table 3 lists the ether compounds (B) used in the Examples and Comparative Examples. Table 4 lists the metal compounds (C) used in the Examples and Comparative Examples.

[0054] [Table 2]

[0055] [Table 3]

[0056] [Table 4]

[0057] The surface treatment agents of the Examples and Comparative Examples were prepared by mixing the resin (A), the ether compound (B), and the inorganic compound (C) to obtain the mass blending ratios shown in Table 5, and then adding deionized water to the resulting mixture in an amount of 1000 g in total to 40 g of solid content, followed by stirring.

[0058] [Table 5]

[0059] <Production of test heat exchanger> The test heat exchanger was an aluminum heat exchanger (NB heat exchanger) for home air conditioners. The test heat exchanger was then subjected to surface treatment under the following treatment conditions.

[0060] <Formation of surface treatment film> The test heat exchanger was immersed for 2 minutes in a treatment bath containing an alkaline degreasing agent "Fine Cleaner 4424" (manufactured by Nihon Parkerizing Co., Ltd.) at a concentration of 20 g / L and a bath temperature of 50°C to remove any dirt or oil adhering to the surface, and then the alkali remaining on the surface was washed away with city water. Next, the test heat exchanger was immersed and coated with the surface treatment agent according to each Example and Comparative Example. This test heat exchanger was placed in a drying oven for 20 minutes in a temperature environment of 150°C to form a surface treatment film on the surface of the test heat exchanger, and an evaluation sample was prepared. The mass of the surface treatment film was 0.8 g / m 2 It was adjusted so that

[0061] <Odor evaluation method> The evaluation sample prepared above was cooled to room temperature and then immediately placed in an air conditioner, with the cooling function turned on and off four times. Each time, one panelist evaluated the odor from a distance of 10 to 20 cm from the air conditioner outlet. The odor evaluations for the cooling function on and off were defined as the initial odor. The evaluation sample was then immersed in deionized water for 72 hours, dried in a 50°C-controlled air dryer for 2 hours, and cooled to room temperature. The evaluation sample was then placed in the air conditioner, with the cooling function turned on and off four times. Each time, one panelist evaluated the odor from a distance of 10 to 20 cm from the air conditioner outlet. The odor evaluations for the cooling function on and off were defined as the post-durability odor. The odor at each timing was evaluated according to the following criteria. The evaluation criteria used odor intensity measured at a specified concentration of isovaleric acid, the odor component used as the standard odor. The evaluation results of the four panelists were averaged, and odor control was considered good if the evaluation standard score was 3 points or less. The results are shown in Table 6. (Evaluation criteria) 5 points: Strong odor (isovaleric acid concentration: 30 μg / L) 4 points: Easily detectable odor (isovaleric acid concentration: 4 μg / L) 3 points: Weak odor that can be identified (recognition threshold: isovaleric acid concentration: 0.4 μg / L) 2 points: barely detectable odor (detection threshold: isovaleric acid concentration: 0.05 μg / L) 1 point: Odorless

[0062] <Drainage evaluation method> The evaluation sample prepared above was placed in an air conditioner, and the air conditioner was turned on. The amount of water retained by the evaluation sample after 30 minutes of cooling was measured. The amount of water retention was calculated as follows: {(weight of evaluation sample after cooling - weight of evaluation sample after drying) / heat transfer area of evaluation sample}. The lower the water retention, the better the drainage and heat exchange efficiency. The evaluation criteria for water retention are shown below, and a score of 3 or less was considered to have good drainage. The evaluation sample was immersed in deionized water for 72 hours, dried for 2 hours in a blast dryer adjusted to 50°C, and then cooled to room temperature before use. The results are shown in Table 6. (Evaluation criteria) 5 points: 70g / m 2 End 4 points: 60g / m 2 More than 70g / m 2 less than 3 points: 50g / m 2 More than 60g / m 2 less than 2 points: 40g / m 2 More than 50g / m 2 less than 1 point: 40g / m 2 less than

[0063] <Corrosion resistance evaluation method> The evaluation samples prepared above were exposed to salt spray testing (JIS Z-2371) for 720 hours, and the rust area on the fins (ratio of white rust area to the total area) was evaluated by visual inspection. The evaluation criteria are shown below. A rating of 3 points or less was considered to have good corrosion resistance. The results are shown in Table 6. (Evaluation criteria) 5 points: white rust area of 70% or more 4 points: White rust area is 50% or more but less than 70% 3 points: White rust area is 30% or more but less than 50% 2 points: White rust area 10% or more, less than 30% 1 point: White rust area less than 10%

[0064] [Table 6]

Claims

1. A surface treatment agent for aluminum-containing metal materials, comprising: a resin (A) having an ethylene structural unit and a hydroxyethylene structural unit; an ether compound (B) serving as a binder and having either or both of an epoxy group and a hydroxyl group; and a metal compound (C) serving as an inhibitor and containing at least one metal selected from Si, Ti, V, Cr, Mn, Co, Zn, Zr, Mo, Ce, and W, wherein the content of the ethylene structural unit in the resin (A) is 1 to 20 mol %.

2. The masses of the resin (A), the ether compound (B), and the metal compound (C) contained in the surface treatment agent are respectively represented by M A , M B and M C Expressed as M A / (M B +M C 2. The surface treatment agent according to claim 1, wherein the surface treatment agent is formulated so as to satisfy the relationship: ##EQU1## where ##EQU2##

3. The masses of the ether compound (B) and the metal compound (C) contained in the surface treatment agent are respectively represented by M B and M C Expressed as M B / M C 3. The surface treatment agent according to claim 1, wherein the surface treatment agent is formulated so as to satisfy the relationship of .gtoreq.0.

0.

4. 4. The surface treatment agent according to claim 1, wherein the metal compound (C) is an oxide containing silicon.

5. A surface treatment agent described in any one of claims 1 to 4, wherein the ether compound (B) is one or more selected from polyalkylene glycols, polyalkylene glycol alkyl ethers, carbohydrates having a pyranose structure or a furanose structure, glycidoxy group-containing silane compounds, and glycidyl ether compounds.

6. A method for producing a surface-treated metal material, comprising the steps of: contacting the surface treatment agent according to any one of claims 1 to 5 with the surface or on the surface of an aluminum-containing metal material; and drying the surface treatment agent after the contacting step.

7. An aluminum-containing metal material having a surface treatment film formed by contacting the surface treatment agent according to any one of claims 1 to 5 with the surface or on the surface.

8. A heat exchanger comprising the aluminum-containing metallic material according to claim 7.

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