JPH0525959B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial application field The present invention provides an oxide film on the surface of an aluminum-based metal such as aluminum or an alloy containing aluminum, which has an opaque white to extremely excellent color fastness and weather resistance. The present invention relates to a surface treatment agent for aluminum-based metals having an oxide film, which produces a grayish-white substance. (b) Conventional technology In recent years, with the improvement of cultural life and changes in lifestyles, there has been a demand for coloring of aluminum-based metal products used in building materials, nameplates, decorative items, daily necessities, vehicles, etc. , especially daily necessities, decorative items,
In the fields of vehicles and building materials, pastel-colored aluminum-based metal products are in high demand because they give a calm and warm feeling to the viewer. By the way, in order to color an aluminum-based metal product in a pastel tone, it is first necessary to color the aluminum-based metal semi-finished product in a basic opaque white to gray-white color. Conventionally, the following surface treatment method has been proposed as a method for coloring an aluminum-based metal semi-finished product in an opaque white to grayish white color. That is, an aluminum-based metal semi-finished product having an anodized film is whitened by immersing it in an aqueous solution with a pH of 7 or more containing one or more alkaline earth metal ions,
Next, a surface finishing (surface treatment) method has been proposed in which a post-treatment is performed to improve the whitening effect of the surface of the aluminum or aluminum alloy material (Japanese Patent Laid-Open No. 53-92345). In the above process, post-treatment to improve the whitening effect includes changing the chemical composition by immersion in an aqueous solution with a pH of 4 or less or in a weak alkaline aqueous solution, and changing the particle size, etc. This method changes the physical and optical properties of the aluminum material, and also dissolves and roughens the oxide film, thereby increasing the diffuse reflectance of the aluminum material surface and making it appear white. . By the way, this method describes whitening the oxide film of aluminum by immersing it in an aqueous solution containing a metal salt that produces a white hydrated metal oxide and organic chelate compounds such as oxalic acid, tartaric acid, and citric acid. has been done. (c) Problems to be Solved by the Invention However, this method requires a large number of steps, as it involves coloring an aluminum-based metal semi-finished product having an anodic oxide film to white or grayish white through the above steps. This method requires two types of electrolysis/reaction devices, their accompanying equipment, and a water washing device, as well as personnel to manage them, resulting in a significant increase in manufacturing costs. Further, in this method, the diffuse reflectance increases and whitening progresses, but the abrasion resistance and durability of the oxide film decrease due to dissolution, roughening, etc. of the oxide film. Furthermore, in this method, aluminum or an aluminum alloy material and an alkaline earth metal compound are mixed with an organic chelate compound such as an organic dicarboxylic acid in the micropores of the oxide film of an aluminum or aluminum alloy material having an oxide film. is fixed, but this bonding force is weak, and for this reason,
During sealing, which is a subsequent process, the alkaline earth metal compound bleeds out, ie, decolorization occurs, and in this sealing process, color unevenness occurs, causing problems such as a lack of practicality. In particular, this method uses an organic chelate compound to combine aluminum or aluminum alloy material with an alkaline earth metal compound, but organic chelate compounds are unstable and have poor corrosion resistance and weather resistance. It is unsatisfactory as a structural material for use in industrial machinery and equipment, as well as in high temperature and humid environments, and does not provide the desired durability when used in building materials, nameplates, and vehicles. In this case, if this type of aluminum-based metal product is used under high temperature and high humidity, the organic chelate compound will carbonize, and local cells will be formed between the generated carbon and the aluminum-based metal, resulting in electrolytic corrosion, resulting in durability. Sexuality is significantly reduced. The present invention was completed as a result of extensive research over many years in view of the above-mentioned technical problems, and consists of an aluminum-based metal and a metal salt that produces white to grayish-white hydrated metal oxides upon hydrolysis. The object of the present invention is to provide a surface treatment agent for aluminum-based metals that solves the above-mentioned problems at once by bonding the above-mentioned metals with an intervening inorganic chelate compound. (d) Means for Solving the Problems In order to achieve the above object, the surface treatment agent for aluminum-based metals having an oxide film of the present invention takes the following technical measures. That is, the surface treatment agent for aluminum-based metals having an oxide film according to claim 1 of the present application contains as essential components metal salts and inorganic chelate compounds that produce white to grayish-white hydrated metal oxides upon hydrolysis. It is. In the surface treatment agent for aluminum-based metals having an oxide film according to claim 2 of the present application, the inorganic chelate compounds used in the surface treatment agent are polyphosphoric acid or a salt thereof, polyphosphorous acid or a salt thereof, or hydroxyapatite. It is characterized by this. In the surface treatment agent for aluminum-based metals having an oxide film according to claim 3 of the present application, the inorganic chelate compounds used in the surface treatment agent are at least one selected from polyphosphoric acid or polyphosphorous acid and polyphosphate or It is characterized by being a mixture of at least one salt selected from polyphosphites, or a mixture of this mixture and hydroxyapatite. The surface treatment agent for aluminum-based metals having an oxide film according to claim 4 of the present application is such that the inorganic chelate compounds used in the surface treatment agent are pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid, or their alkali metal salts, ammonium salts, or selected from alkaline earth orthodihydrogen phosphates, orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, tripolyphosphorous acid, tetrametaphosphorous acid, or alkali metal salts or ammonium salts thereof. It is characterized in that it is at least one type. In the surface treatment agent for aluminum-based metals having an oxide film according to claim 5 of the present application, the inorganic chelate compounds used therein are pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid. at least one acid selected from acid, hypophosphoric acid, tripolyphosphorous acid, or tetrametaphosphorous acid, and at least one acid selected from these alkali metal salts or ammonium salts or alkaline earth orthodihydrogen phosphates. It is characterized in that it is a mixture of salts of seeds. The present invention will be explained in detail below. First, the invention of claim 1 of the present application will be explained in detail. That is, the invention of claim 1 of the present application is a surface treatment of an aluminum-based metal having an oxide film, the essential components of which are a metal salt and an inorganic chelate compound that produce white to off-white hydrated metal oxides upon hydrolysis. It is a drug. The metal salts used in the present invention that produce white to gray-white hydrated metal oxides upon hydrolysis are metal salts that are soluble or sparingly soluble in water, and which produce white to gray-white hydrated metal oxides upon hydrolysis. It is not particularly limited as long as it is a metal salt that produces the following. Specific representative examples of the first metal salt are:
At least one of zinc salts, calcium salts, barium salts, strontium salts, magnesium salts, aluminum salts, and the like can be mentioned. The concentration of the metal salt is preferably 0.1 to 100 g/, particularly preferably 0.5 to 50 g/,
If the concentration is less than 0.1g/, the concentration may become too thin and a sufficiently dense film may not be obtained;
Exceeding this is not preferable because the concentration becomes too high and when the liquid temperature drops (for example, in winter), metal salts precipitate and the concentration changes, which may make it difficult to manage the surface treatment agent. The surface treatment agent for aluminum-based metals having an oxide film of the present invention contains the above-mentioned metal salt and inorganic chelate compounds as essential components. In the present invention, the inorganic chelate compounds used not only stabilize the metal ions in the surface treatment agent, but also particularly stabilize the oxide film of the aluminum-based metal having an oxide film, by forming products from the metal salts on the oxide film part of the aluminum metal. (hydrated metal oxides, etc.) can be bonded extremely easily, uniformly, and firmly. In this way, when inorganic chelate compounds are used, the products from the metal salt are fixed in the oxide film of an aluminum metal having an oxide film due to some of the protons in the inorganic chelate compounds. (H ⁺ ), alkali metal ions or ammonium ions and products from metal salts are substituted and combined, and the remaining protons (H ⁺ ), alkali metal ions or ammonium ions form micropores in the oxide film of aluminum-based metals. It is understood that this is because the product from the metal salt is substituted and bonded with Al ³⁺ that is electrostatically coordinated within the oxide film, thereby fixing the product from the metal salt within the micropores of the oxide film. Also, hydrolysates from metal salts (colloidal substances)
is negatively charged and is electrically attracted around Al ³⁺ and other metal ions (alkali metal ions and metal ions from metal salts) in the micropores of the oxide film. This is thought to be because products from the metal salt concentrate in the micropores, and as a result, even complexly formed aluminum metals can be uniformly colored. Furthermore, since the products generated from metal salts are electrostatically fixed within these micropores, they are difficult to desorb, or decolorize, during pore sealing, and are thought to be able to be uniformly colored. . In fact, pastel colored films with excellent properties can be obtained by using inorganic chelate compounds. In the present invention, the inorganic chelate compounds used are not particularly limited as long as they exhibit at least one of the above-mentioned functions, and specifically include, for example, polyphosphoric acid or a salt thereof, Examples include polyphosphorous acid or a salt thereof, hydroxyapatite, thiosulfate, boric acid or an alkali metal salt or ammonium salt thereof, polyboric acid or an alkali metal salt or ammonium salt thereof, and the like. These include water-insoluble inorganic chelate compounds, which can be used by dispersing them in water. The concentration of the above inorganic chelate compounds is as follows:
Although it varies depending on the type and concentration of the metal salt used,
In general, the range of 0.1 to 50 g/, especially the range of 1 to 20 g/ is preferable; if it is less than 0.1 g/, the desired effect cannot be obtained, and if it exceeds 50 g/, the effect will be limited and it will be uneconomical. be. Incidentally, in the present invention, an organic polar solvent may be used, but the organic polar solvent is not particularly limited as long as it is a water-soluble polar solvent. Specifically, for example, methanol, ethanol, etc. Lower alcohols, ketones such as acetone, methyl ethyl ketone, diethyl ketone, ethers,
Examples include ethers such as diethyl ether. The concentration of the organic polar solvent is preferably 0.1 to 25% by volume. That is, since the surface treatment agent of the present invention contains the above-mentioned inorganic chelate compounds, the surface treatment agent of the present invention can be coated with an excellent white or white color by simply immersing an aluminum metal having an oxide film. Although it is possible to form a grayish-white dense film, it is preferable to include an organic polar solvent therein, since the product from the metal salt can be stabilized. If the concentration of the above organic polar solvent is less than 0.1% by volume, it may become too dilute and sufficient effects may not be obtained.On the other hand, if it exceeds 25% by volume, the concentration becomes too high and affects the solubility of the metal salt. This is not desirable because it gives The surface treatment agent for aluminum-based metals having an oxide film of the present invention (hereinafter referred to as surface treatment agent) contains the above metal salt and inorganic chelate compounds as essential components, and water and, if desired, a PH adjuster. added solution. The pH of this surface treatment agent is in the range of 1.5 to 8.
In particular, it is desirable to keep the pH in the range of 3 to 6, and the pH is 1.5.
If the pH is less than 8, the acidity may become too high and the film may be destroyed. Conversely, if the pH exceeds 8, the metal salts may be hydrolyzed and the surface treatment agent may become cloudy during storage or handling. , the inorganic chelate compound is hydrolyzed and its effectiveness is reduced.Moreover, when an aluminum metal with an oxide film is immersed, the white to gray-white hydrated metal oxide particles generated by hydrolysis become large. This is not preferable because there is a risk that it will become too thick and be unable to penetrate into the surface portion (oxide film portion) of the aluminum-based metal, or that a dense film may not be obtained. The above PH regulators include inorganic acids such as sulfuric acid, phosphoric acid, and boric acid, organic acids such as acetic acid, citric acid, succinic acid, gluconic acid, glycine, malonic acid, oxalic acid, and formic acid, and alkali metal hydroxides. , carbonates or bicarbonates, ammonia, amines, alkali metal salts of organic acids, etc. Among these, inorganic acids and bases (including carbonates and bicarbonates) have particularly good durability and corrosion resistance. is desirable because it is extremely high. One type of these acids or bases or alkali metal salts of organic acids may be used, or two or more types may be used in combination, and the combination thereof may be particularly effective in some cases. Next, the invention of claim 2 of the present application will be explained in detail. The invention of claim 2 of the present application is that in the surface treatment agent of claim 1, the inorganic chelate compounds used in this surface treatment agent are polyphosphoric acid or its salt, polyphosphorous acid or its salt, or hydroxyapatite. It is characterized by: In other words, the surface treatment agent of claim 1 of the present application is not particularly limited as long as it is an inorganic keyleto compound used therein, whereas claim 2 of the present application
In the invention, phosphorus-based keyleto compounds are specified, and phosphorus-based keyleto compounds are extremely stable, and the obtained white to grayish-white oxide film has extremely excellent corrosion resistance and weather resistance.
It is suitable for use in structural materials, building materials, nameplates, and vehicles that are used in harsh environments such as high humidity. The surface treatment agent according to claim 2 of the present application specifies the inorganic keyleto compound of the surface treatment agent in the invention according to claim 1, and therefore, other requirements of the surface treatment agent, such as metal salts, are specified. type and concentration,
Furthermore, the PH range of the surface treatment agent, the PH adjuster, etc. are the same as in the invention of claim 1 above. Examples of the polyphosphoric acids include _H2O - _{P2O5 -} based crystalline compounds and their hydrates, pyrophosphoric acid, tripolyphosphoric acid, and tetrametaphosphoric acid. Typical examples of polyphosphoric acid salts include alkali metal salts, ammonium salts, alkaline earth orthodihydrogen phosphates, and the like of the above-mentioned polyphosphoric acid (condensed phosphoric acid). By the way, condensed phosphates are synthesized by dehydrating phosphates, and examples of the condensed phosphates include simple diphosphates to long-chain polycondensates with a molecular weight of 10 ⁶ . Specifically, for example, tetrasodium pyrophosphate,
Disodium dihydrogen pyrophosphate (sodium acid phosphate), tetraammonium pyrophosphate, diammonium dihydrogen pyrophosphate, diammonium dihydrogen pyrophosphate, tetrapotassium pyrophosphate, dipotassium dihydrogen pyrophosphate (sodium acid phosphate), Diammonium dipotassium pyrophosphate, dipotassium disodium pyrophosphate, ammonium ultraphosphate, sodium ultraphosphate, potassium ultraphosphate, sodium trimetaphosphate ( _NaPO3 )
₃ , sodium hydrogen trimetaphosphate, ammonium trimetaphosphate ( _NH4PO3 ) ₃ , ammonium hydrogen trimetaphosphate, potassium trimetaphosphate ( _{KPO3 ) 3} , potassium hydrogen trimetaphosphate, potassium ammonium trimetaphosphate, potassium sodium trimetaphosphate, potassium tripolyphosphate , Potassium hydrogen tripolyphosphate, Sodium tetrametaphosphate, Sodium hydrogen tetrametaphosphate (acidic sodium phosphate), Ammonium tetrametaphosphate, Ammonium hydrogen tetrametaphosphate, Sodium ammonium tetrametaphosphate, Tetrapotassium tetrametaphosphate, Hydrogen tetrametaphosphate Potassium (acidic sodium phosphate), potassium ammonium tetrametaphosphate, cyclic and long-chain condensed sodium phosphates such as dipotassium disodium tetrametaphosphate, condensed sodium hydrogen phosphate, condensed sodium ammonium phosphate, condensed potassium phosphate , condensed potassium hydrogen phosphate, condensed potassium ammonium phosphate, condensed ammonium phosphate, condensed ammonium hydrogen phosphate, condensed potassium sodium phosphate, crystalline sodium hyperpolyphosphate,
Examples include sodium hypopolyphosphate, sodium ammonium hypopolyphosphate, potassium sodium hypopolyphosphate, potassium hypopolyphosphate, potassium hydrogenpolyphosphate, ammonium hydrogenpolyphosphate, ammonium hyperpolyphosphate, and the like. Examples of the above-mentioned polyphosphorous acids include orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, tripolyphosphorous acid, tetrametaphosphorous acid, and the like. Typical examples of polyphosphorous acid salts include the above-mentioned alkali metal salts and ammonium salts of polyphosphorous acid. Furthermore, another example of the above-mentioned inorganic chelate compound is hydroxyapatite. These include water-insoluble phosphorus chelate compounds, which can be used by dispersing them in water. By the way, in the present invention, disodium hydrogen orthophosphate, monosodium dihydrogen orthophosphate,
Disodium potassium orthophosphate, monosodium dipotassium orthophosphate, sodium ammonium hydrogen orthophosphate, sodium calcium orthophosphate, sodium agnesium orthophosphate, potassium potassium orthophosphate, potassium magnesium orthophosphate, calcium pyrophosphate, magnesium pyrophosphate, calcium disodium pyrophosphate, Calcium dipotassium pyrophosphate, magnesium pyrophosphate, magnesium disodium pyrophosphate, magnesium dipotassium pyrophosphate, calcium hydrogen orthophosphate dihydrate, magnesium hydrogen orthophosphate, monofluorophosphate, difluorophosphate, hexafluorophosphate,
Whitening or graying aids such as soluble alkali silicate such as sodium silicate, potassium silicate, or lithium silicate, or fine particulate aqueous dispersions of aluminum silicate, potassium aluminum silicate, sodium aluminum silicate, and calcium aluminum silicate may be added. is desirable. The concentration of this auxiliary agent varies depending on the type and concentration of the inorganic chelate compound used, as well as the type of auxiliary agent, but it is usually in the range of 1 to 50 g/, preferably 5 to 30 g/. is desirable. If the amount of this auxiliary agent is less than 1 g/g, the amount is too small to obtain the desired effect, while if it exceeds 50 g/g, the effect will be limited and it will be uneconomical. These include water-insoluble whitening or graying aids, which can be used by dispersing them in water. Next, the invention of claim 3 of the present application will be explained in detail. In the surface treatment agent for aluminum-based metals having an oxide film according to claim 3 of the present application, the inorganic chelate compounds used in the surface treatment agent are at least one selected from polyphosphoric acid or polyphosphorous acid and polyphosphate or It is characterized by being a mixture of at least one salt selected from polyphosphites, or a mixture of this mixture and hydroxyapatite. The invention of claim 3 of the present application provides that, in the above-mentioned surface treatment agent, the inorganic chelate compounds used therein are a mixture of acidic phosphorus-based chelate compounds and neutral or alkaline phosphorus-based chelate compounds, The mutual buffering effect reduces PH fluctuations, resulting in an extremely excellent white to grayish-white colored film. That is, when an aluminum-based metal having an oxide film is immersed in a surface treatment agent, and products from metal salts are sequentially bonded to the surface of the oxide film via a phosphorus-based chelate compound, hydrogen ions are formed. , ammonium ions, alkali metal ions, etc. remain in the surface treatment solution, and as a result, the PH of the surface treatment solution fluctuates, but by forming a mixture in this way, PH fluctuations are suppressed, and thereby, An excellent colored film can be obtained. In other words, the surface treatment agent of claim 3 of the present application is the above-mentioned surface treatment agent, in which the inorganic keyleto compound of the surface treatment agent is specified as a mixture of acidic phosphorus-based keyleto compounds and neutral or alkaline phosphorus-based keyleto compounds. Therefore, other requirements for this surface treatment agent, such as the type and concentration of metal salt,
Furthermore, the PH range of the surface treatment agent, the PH adjuster, etc. are the same as in the invention of claim 1 above. In addition, this acidic phosphorus-based chelate compound (A)
and neutral to alkaline phosphorus-based chelate compounds (B), in which (A) and (B)
The mixing ratio is (A) 1 to (B) in molar ratio.
It is desirable that the pH is in the range of 0.2 to 5, preferably in the range of 0.3 to 3. Anything outside this range is undesirable because the pH buffering effect becomes poor. The invention of claim 4 of the present application will be explained in detail. The surface treatment agent for aluminum-based metals having an oxide film according to claim 4 of the present application is such that the inorganic chelate compounds used in the surface treatment agent are pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid, or their alkali metal salts, ammonium salts, or selected from alkaline earth orthodihydrogen phosphates, orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, tripolyphosphorous acid, tetrametaphosphorous acid, or alkali metal salts or ammonium salts thereof. It is characterized in that it is at least one type. This surface treatment agent is specifically selected from among phosphorus-based keyleto compounds, which are particularly excellent, and can provide a white to gray-white oxide film with even better weather resistance and corrosion resistance. This surface treatment agent is specified to have excellent effects as a phosphorus-based chelate compound used therein, and therefore, other requirements of the surface treatment agent according to claim 4, such as metal salts, are specified. The type and concentration of the surface treatment agent, the PH range of the surface treatment agent, the PH adjuster, etc. are the same as those of the invention of claim 1 above. The invention of claim 5 of the present application will be explained in detail. In the surface treatment agent for aluminum-based metals having an oxide film according to claim 5 of the present application, the inorganic chelate compounds used therein are pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid. at least one acid selected from acid, hypophosphoric acid, tripolyphosphorous acid, or tetrametaphosphorous acid, and at least one acid selected from these alkali metal salts or ammonium salts or alkaline earth orthodihydrogen phosphates. It is characterized in that it is a mixture of salts of seeds. As the inorganic keyleto compounds used for this surface treatment agent, phosphorus-based keyleto compounds with excellent effects are specified, and acidic phosphorus-based keyleto compounds with excellent effects and neutral to By creating a mixture of alkaline phosphorus-based chelate compounds, due to their mutual buffering effect.
Fluctuations in pH are reduced, and furthermore, a more excellent white to grayish-white colored film can be obtained. The PH range of the processing agent, the PH adjuster, etc. are the same as those in the invention of claim 3 above. In the present invention, an aluminum-based metal having an oxide film refers to an aluminum-based metal in which an oxide film is formed on the surface of aluminum or an alloy containing aluminum by chemical or electrochemical (anodic oxidation). It is preferable that a white to grayish-white oxide film with even better characteristics can be obtained. A known anodic oxidation method is employed to form an anodic oxide film on the aluminum-based metal. Specifically, for example, inorganic acids such as sulfuric acid, phosphoric acid, and chromic acid; organic acids such as oxalic acid, paraphenolsulfonic acid, sulfosalicylic acid, and malonic acid; or sodium hydroxide, trisodium phosphate, etc. An anodic oxide film is formed in an aqueous solution by electrolysis using direct current, alternating current, pulse, PR waves, or AC/DC superposition method. Next, examples of use of the surface treatment agent of the present invention will be described below. When coloring the surface of an aluminum-based metal having an oxide film white to grayish white, the above-mentioned surface treatment agent is placed in a treatment tank, and the concentration is adjusted with water and/or an organic polar solvent or an inorganic chelate compound as desired. or adjust the PH with a PH adjuster,
The temperature of the treatment solution is usually adjusted to room temperature to 75°C, preferably 40 to 70°C, and the aluminum metal is added to this solution for usually 10 seconds to 30 minutes, preferably 1 minute to
When immersed for 20 minutes, a dense white to off-white film with excellent properties can be obtained in a single treatment. In addition, the surface treatment agent of the present invention can provide a uniform and dense white to grayish-white film simply by immersing aluminum metal, so it can be used for coloring with excellent properties even when electrolyzed without strict conditions. A film can be obtained. (e) Effect The present invention has the above configuration, and when an inorganic keyleto compound is used in a surface treatment agent, a white to grayish-white hydrated metal oxide is produced by the inorganic keyleto compound due to a change in pH. In particular, it not only stabilizes the hydrated metal oxides, but also has the effect of extremely easily, uniformly and strongly bonding the hydrated metal oxides to the oxide film part of the aluminum-based metal having an oxide film. In this way, when inorganic keyleto compounds are used, the product from the metal salt is fixed in the oxide film of an aluminum-based metal having an oxide film. Hydrogen ions, alkali metal ions, or ammonium ions replace and combine with products from metal salts, and the remaining hydrogen ions, alkali metal ions, or ammonium ions electrostatically enter the micropores of the oxide film of aluminum-based metals. This is thought to be due to the fact that the product from the metal salt is bonded to the coordinating Al ³⁺ , thereby fixing the product from the metal salt within the micropores of the oxide film. Also, hydrolysates from metal salts (colloidal substances)
is negatively charged and is electrically attracted around Al ³⁺ and other metal ions (alkali metal ions and metal ions from metal salts) in the micropores of the oxide film. Products from the metal salt concentrate in the micropores, and as a result, even complexly formed aluminum metals can be uniformly colored. Furthermore, since the product produced from the metal salt is electrostatically fixed within the micropores, it is difficult to desorb, that is, decolorize, during sealing, and has the effect of uniformly coloring the pores. In particular, since the surface treatment agent of the present invention can chemically form a white to grayish-white, uniform and dense film just by immersion, it is easy to form a film with excellent properties even by electrolysis. Therefore, there is no need for expensive electrolysis equipment or accompanying control equipment, and moreover, electrolysis can be used without strictly controlling the electrolyte, electrolysis conditions, current density distribution, etc.
It has the ability to form a uniform film even on aluminum-based metals that have complex oxide films. In particular, this method uses inorganic chelate compounds rather than organic chelate compounds, and these inorganic chelate compounds are stable and have extremely excellent corrosion resistance and weather resistance.
As a result, it can be used particularly for industrial machinery and equipment, structural materials used in high temperature and humid environments, building materials, nameplates, and vehicles. (f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto. Examples 1 to 6 The composition of each surface treatment agent of Examples 1 to 6 was
Shown in the table. Comparative Examples 1 to 3 Samples were prepared using oxalic acid, tartaric acid, and citric acid as keyleto compounds as the respective components in Examples 1 to 3 above. Examples 7 to 10 The composition of each surface treatment agent of Examples 7 to 10 was
Shown in the table.

【table】

【table】

[Table] Examples 11-20 Table 3 shows the compositions of the surface treatment agents of Examples 11-20.

【table】

[Table] Using each of the above Examples and Comparative Examples, a white to grayish-white coloring test was conducted under the conditions shown in Table 4. The anodic oxide film used in each of the above Examples and Comparative Examples as well as the Reference Examples described below was prepared by pre-treating a pure aluminum plate with normal degreasing, etc., with a sulfuric acid concentration of 180 g/, a bath temperature of 20°C, and a current density. 1.5A/ ^dm2
It was obtained by direct current electrolysis for 18 minutes under the following conditions. In this case, the thickness of the anodic oxide film was 8 μm. The results are shown in Table 4.

【table】

[Table] From the color tone results shown in Table 4, the surface treatment agent of the present invention was able to color the anodic oxide film to a uniform white color, and almost no color unevenness was observed. In addition, in the surface treatment agent of the present invention, by using a mixture of acidic phosphorus-based keyleto compounds and neutral or alkaline phosphorus-based keyleto compounds as the inorganic keyleto compounds used therein, mutual buffering effects can be achieved. It has been found that the variation in PH is reduced by this process, a more excellent white to gray-white colored film can be obtained, and PH is extremely easy to control. By the way, when the whitening oxide film (aluminum metal) of each of the above-mentioned Examples was subjected to a corrosion resistance test in an atmosphere of a temperature of 80° C. and a relative humidity of 95%, no abnormality was observed even after 3 months had passed. When the white film of each of the above Examples was colored and sealed using a dye or metal salt by a known screen printing method, thermal transfer method, dipping method, etc., a uniform and dense pastel-like film was obtained. On the other hand, the comparative examples have large color unevenness and lack practicality, and the white films of these comparative examples can be produced using dyes or metal salts, using known screen printing methods, thermal transfer methods, dipping methods, etc. When colored and sealed, a pastel-like film could not be obtained. In addition, when the whitening oxide film (aluminum-based metal) of each of the above comparative examples was subjected to a corrosion resistance test at a temperature of 80°C and a relative humidity of 95%, corrosion was observed in 25 hours, making it impossible to use it under harsh conditions. It was not possible. (g) Effects of the Invention The surface treatment agent of the present invention has the above-mentioned structure and uses inorganic keyleto compounds in the surface treatment agent, so that a film with extremely excellent corrosion resistance and weather resistance can be obtained from the surface treatment agent. It can be obtained chemically by simply immersing it in a surface treatment agent, and a white to grayish-white, uniform and dense film can be formed just by dipping it in a surface treatment agent, so it has excellent properties even when electrolyzed. It is possible to easily form a film of By electrolysis,
It has the effect of forming a uniform film even on aluminum-based metals that have complex oxide films. In particular, this surface treatment agent does not use organic chelate compounds, but inorganic chelate compounds, which are extremely chemically stable and have excellent corrosion resistance and weather resistance. As a result, it can be used particularly in industrial machinery and equipment, structural materials used in high temperature and humid environments, building materials, nameplates, and even vehicles. In addition, in the surface treatment agent of the present invention, since the inorganic keyleto compounds used therein are a mixture of acidic phosphorus-type keyleto compounds and neutral or alkaline phosphorus-type keyleto compounds, the mutual buffering effect can be improved. Therefore, fluctuations in PH are reduced, and as a result, PH management becomes extremely easy, and as a result, oxide film treatment becomes easy and productivity is significantly improved.

Claims (1)

[Scope of Claims] 1. A surface treatment agent for aluminum-based metals having an oxide film, which contains as essential components a metal salt and an inorganic chelate compound that produce white to off-white hydrated metal oxides upon hydrolysis. 2. The surface treatment agent for aluminum metal having an oxide film according to claim 1, wherein the inorganic chelate compound is polyphosphoric acid or a salt thereof, polyphosphorous acid or a salt thereof, or hydroxyapatite. 3. The inorganic chelate compound is a mixture of at least one salt selected from polyphosphoric acid or polyphosphorous acid and at least one salt selected from polyphosphate or polyphosphite, or this mixture and hydroxyapatite. The surface treatment agent for aluminum-based metals having an oxide film according to claim 1, which is a mixture of the following. 4 Inorganic chelate compounds include pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid, or their alkali metal salts, ammonium salts, alkaline earth orthodihydrogen phosphates, orthophosphorous acid, pyrophosphorous acid, metaphosphorous acid , hypophosphoric acid, tripolyphosphorous acid, tetrametaphosphorous acid, or an alkali metal salt or ammonium salt thereof, according to claim 2 or 3. agent. 5 Inorganic chelate compounds include pyrophosphoric acid, tripolyphosphoric acid, tetrametaphosphoric acid orthophosphorous acid,
At least one acid selected from pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, tripolyphosphorous acid, or tetrametaphosphorous acid, and an alkali metal salt or ammonium salt thereof or an alkaline earth orthodihydrogen phosphorus. The surface treatment agent for aluminum-based metals having an oxide film according to claim 4, which is a mixture of at least one salt selected from acid salts.