Anodic oxide coating film, anodic oxidation treatment liquid, anodic oxidation treatment method, and industrial product

Abstract

The present invention provides an anodic oxide coating film on which a pore-sealing treatment can be performed when forming the anodic oxide coating film on aluminum or an aluminum alloy, and from which a pore-sealed coating film having excellent thermal crack resistance is formed by performing the pore-sealing treatment on the anodic oxide coating film. The present invention also provides: an anodic oxidation treatment liquid from which said anodic oxide coating film can be formed, and from which a pore-sealed coating film having excellent thermal crack resistance is formed by performing a pore-sealing treatment on said anodic oxide coating film; and an anodic oxidation treatment method using said anodic oxidation treatment liquid.　The present invention provides an anodic oxide coating film characterized in that the amount of phosphorus adsorbed on the surface thereof after being subjected to a pore-sealing treatment is 0.1-4.0 at%.

Description

Anodized film, anodized treatment solution, anodized treatment method, and industrial product

[0001] The present invention relates to an anodic oxide film, an anodizing solution, an anodizing method, and an industrial product.

[0002] Conventionally, aluminum and aluminum alloys (hereinafter also referred to as "aluminum, etc.") have been subjected to an anodized oxide film formation treatment (anodizing treatment) to form an oxide film on the surface in order to impart scratch resistance and corrosion resistance.

[0003] As an anodizing treatment, Patent Document 1 proposes a method for producing an anodized film, which includes a first anodizing treatment step in which a voltage is applied in an aqueous sulfuric acid solution as an electrolyte to form an anodized film with high heat insulation properties, and a second anodizing treatment step in which a voltage higher than that applied in the first anodizing treatment step is applied in an oxalic acid solution as an electrolyte.

[0004] However, Patent Document 1 does not fully consider the sealing treatment of the anodized film, and there is room for improvement. The anodized film formed by anodizing is subjected to a sealing treatment in a subsequent process. In this specification, such a sealed anodized film is sometimes referred to as a "sealed film," but this concept is included in the anodized film in this specification. Sealed films have a problem in that cracks occur on the surface when heated at high temperatures after sealing.

[0005] Therefore, when forming an anodized oxide film on aluminum or an aluminum alloy, there is a need for the development of an anodized oxide film that can be subjected to a sealing treatment. There is also a need for the development of an anodized treatment solution that can form such an anodized oxide film and that seals the anodized oxide film to form a sealed film that has excellent heat crack resistance, and an anodized treatment method that uses such an anodized treatment solution.

[0006] Japanese Patent Application Laid-Open No. 2018-090897

[0007] An object of the present invention is to provide an anodized oxide film that can be sealed when formed on aluminum and aluminum alloys, and that the sealed film formed by sealing the anodized oxide film has excellent heat crack resistance. Another object of the present invention is to provide an anodized treatment solution that can form the anodized oxide film and that can seal the anodized oxide film to produce a sealed film that has excellent heat crack resistance, and an anodized treatment method that uses the anodized treatment solution.

[0008] The present inventors have conducted extensive research to achieve the above-mentioned object, and as a result have found that the above-mentioned object can be achieved by using an anodized coating or the like having a phosphorus adsorption amount, pore number, pore diameter, and cell diameter within specific ranges, thereby completing the present invention.

[0009] That is, the present invention relates to the following anodized film, anodized treatment solution, anodized treatment method, and industrial product: 1. An anodized film characterized in that the amount of phosphorus adsorbed on the surface after sealing treatment is 0.1 at% or more and 4.0 at% or less. 2. The anodized film according to item 1, wherein the amount of phosphorus adsorbed on the surface after sealing treatment is 0.1 at% to 3.0 at% or less. 3. The number of pores on the surface is 50 / μm. ２ More than 120 pieces / μm ２ Item 4. An anodic oxide film characterized by a surface pore diameter of 38 nm or more. 5. An anodic oxide film characterized by a surface cell diameter of 89 nm or more. 6. An anodic oxide film formed using an anodizing treatment solution characterized by containing an organic acid and a phosphorus compound. 7. The anodic oxide film according to any one of Items 1 to 6, wherein the anodic oxide film is anodized and then subjected to a sealing treatment. 8. An anodizing treatment solution characterized by containing an organic acid and a phosphorus compound. 9. An anodizing method characterized by anodizing using an anodizing treatment solution containing an organic acid and a phosphorus compound. 10. An anodizing method characterized by anodizing using an anodizing treatment solution containing an organic acid and a phosphorus compound, and then performing a sealing treatment. 11. An industrial product having the anodic oxide film according to any one of Items 1 to 6. 12. An industrial product having the anodic oxide film according to Item 7.

[0010] The anodized oxide film of the present invention is an anodized oxide film that can be sealed when formed on aluminum and aluminum alloys, and the sealed film formed by sealing the anodized oxide film exhibits excellent heat-cracking resistance. The anodizing solution of the present invention can form the anodized oxide film, and the sealed film formed by sealing the anodized oxide film exhibits excellent heat-cracking resistance. The anodizing method of the present invention can form the anodized oxide film, and the sealed film formed by sealing the anodized oxide film exhibits excellent heat-cracking resistance.

[0011] 1 is a diagram showing test results of Comparative Example 2 and Example 3 after anodizing treatment (unsealed) and sealing treatment. It is a diagram showing an SEM image of the unsealed hole of Comparative Example 2 in FIG. 1 at 200,000 magnification. It is a diagram showing an SEM image of the unsealed hole of Comparative Example 2 in FIG. 1 at 100,000 magnification. It is a diagram showing an SEM image of the sealed hole of Comparative Example 2 in FIG. 1 at 100,000 magnification. It is a diagram showing an SEM image of the unsealed hole of Example 3 in FIG. 1 at 200,000 magnification. It is a diagram showing an SEM image of the unsealed hole of Example 3 in FIG. 1 at 100,000 magnification. It is a diagram showing an SEM image of the sealed hole of Example 3 in FIG. 1 at 100,000 magnification. It is a diagram showing the results of XPS elemental analysis of the surfaces of the anodized films (unsealed) of Example 3 and Comparative Example 2. It is a diagram showing photographs of the surfaces of the sealed films of Comparative Example 2 and Example 3.

[0012] 1. Anodized Oxide Film The anodized oxide film of the present invention is an anodized oxide film having a surface phosphorus adsorption amount of 0.1 at% or more and 4.0 at% or less. If the surface phosphorus adsorption amount is less than 0.1 at%, the heat crack resistance of the sealed film formed by sealing the anodized oxide film will be poor. If the surface phosphorus adsorption amount exceeds 4.0 at%, sufficient sealing performance will not be obtained. The surface phosphorus adsorption amount is preferably 0.7 at% or more, more preferably 1.0 at% or more. Furthermore, the surface phosphorus adsorption amount is preferably 3.0 at% or less, more preferably 2.6 at% or less, and even more preferably 2.0 at% or less.

[0013] The amount of adsorbed phosphorus on the surface can be measured by performing elemental analysis of the anodized film surface using an XPS measurement device (manufactured by ULVAC-PHI, Inc., product name PHI5000 VersaProbeIII) under the following conditions: X-ray setting: 100 μ, 25 W, 15 kV, pass energy: 55 eV, time per step: 50 ms, sputter mode: alternating, sputter setting: 2 kV 1×1.

[0014] The anodic oxide film of the present invention also has a surface pore count of 50 / μm ２ More than 120 pieces / μm ２ The anodized film has a surface pore count of 50 / μm or less. ２ or less than 120 particles / μm ２ If the number of pores on the surface exceeds 80 / μm, the heat crack resistance of the sealing treatment film formed by sealing the anodized film will be poor. ２ More than 100 pieces / μm ２ The following is preferred:

[0015] The number of pores on the surface was determined by observing the surface of the anodized film with an FE-SEM microscope and randomly measuring pores of 1 μm ２ The measurement can be performed by counting the number of pores present in the range.

[0016] The anodized oxide film of the present invention is also an anodized oxide film having a surface pore size of 38 nm or more. If the surface pore size is less than 38 nm, the heat crack resistance of the sealed film formed by sealing the anodized oxide film will be poor. The surface pore size of the anodized oxide film is preferably 45 nm or more and 70 nm or less.

[0017] The pore size on the surface was determined by observing the surface of the anodized film with an FE-SEM microscope (JSM-7900F, manufactured by JEOL Ltd.) and randomly setting the pore size to 0.5 μm. ２ The pore diameters of the pores present in the range are measured, and the average value of 20 points is taken as the measured value of the pore diameter on the surface.

[0018] The anodized oxide film of the present invention is also an anodized oxide film having a surface cell diameter of 89 nm or more. If the surface cell diameter is less than 89 nm, the heat crack resistance of the sealed film formed by sealing the anodized oxide film will be poor. The surface cell diameter of the anodized oxide film is preferably 95 nm or more and 150 nm or less, and more preferably 95 nm or more and 140 nm or less.

[0019] The cell diameter on the surface was determined by observing the surface of the anodized film with an FE-SEM microscope and randomly setting the cell diameter to 0.5 μm. ２ The cell diameter of the cells present in the range is measured, and the average value of 10 points is taken as the measured value of the cell diameter on the surface.

[0020] The anodic oxide film of the present invention exhibiting the above-mentioned properties can be formed by the anodizing method of the present invention described below. That is, the anodic oxide film of the present invention may be an anodic oxide film formed using an anodizing treatment solution containing an organic acid and a phosphorus compound. Such an anodic oxide film also constitutes the present invention.

[0021] The anodized film of the present invention may be subjected to a sealing treatment after anodizing treatment. As a method for performing the sealing treatment, the sealing treatment method described later in this specification can be suitably used.

[0022] Because the anodized oxide film of the present invention has the above-mentioned configuration, it can be subjected to a sealing treatment when formed on aluminum and aluminum alloy industrial products, and the sealed film formed by sealing the anodized oxide film has excellent heat crack resistance. Such industrial products having the anodized oxide film of the present invention, and industrial products having the anodized oxide film obtained by anodizing the anodized oxide film of the present invention and then sealing the same, are also part of the present invention.

[0023] 2. Anodizing Solution The anodizing solution of the present invention is an anodizing solution characterized by containing an organic acid and a phosphorus compound. The anodizing solution of the present invention is an anodizing solution used for anodizing aluminum or an aluminum alloy.

[0024] The anodizing treatment solution of the present invention is preferably an anodizing treatment solution for aluminum or an aluminum alloy, characterized in that it contains (A) at least one acid component selected from the group consisting of oxalic acid, malonic acid, malic acid, citric acid, adipic acid, L-tartaric acid, and hydrates thereof, and (B) at least one component selected from the group consisting of phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, tripolyphosphoric acid, and phosphorus-containing anionic chelate compounds.

[0025] An anodizing solution is typically used to form an anodized oxide film on aluminum and aluminum alloys. The anodized oxide film formed using the anodizing solution is subsequently subjected to a sealing treatment. Heating the sealed film at high temperatures can cause cracks to form on the surface of the sealed film. If an anodizing treatment is performed using a conventional anodizing solution containing a phosphorus-containing compound such as phosphoric acid to prevent the occurrence of cracks, the sealing treatment in the subsequent step will be hindered and the sealing will be insufficient. The anodizing solution of the present invention contains an organic acid and a phosphorus compound. In particular, the anodizing solution contains a specific acidic component (A) and at least one component selected from the group consisting of phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, tripolyphosphate, and a phosphorus-containing anionic chelate compound (B). This increases the electrolytic voltage of the anodizing treatment, suppresses the inhibition of the sealing treatment, and enables more efficient sealing.

[0026] The anodizing solution of the present invention will be described in detail below.

[0027] (Aluminum or Aluminum Alloy) The anodizing solution of the present invention is preferably an anodizing solution for aluminum or an aluminum alloy.

[0028] The aluminum is not particularly limited, and examples thereof include general pure aluminum. Furthermore, the aluminum alloy is not particularly limited, and various aluminum-based alloys can be used. Specific examples of aluminum alloys include wrought alloys designated by JIS-A numbers in the 1,000 to 7,000 range, and various aluminum-based alloy groups, such as cast and die-cast materials designated by AC and ADC numbers. More specific examples of aluminum alloys include JIS-A5052, A6061, A6063, and the like, designated by JIS.

[0029] ((A) Organic Acid) The organic acid (hereinafter also referred to as "component (A)") is not particularly limited, and for example, it is preferable to use at least one acid component selected from the group consisting of oxalic acid, malonic acid, malic acid, citric acid, adipic acid, L-tartaric acid, and hydrates thereof. Oxalic acid is more preferable as component A. Hydrates of these can also be suitably used.

[0030] The organic acids may be used alone or in combination of two or more.

[0031] The content of the organic acid in the anodizing treatment solution of the present invention is preferably 20 g / L to 80 g / L, more preferably 30 g / L to 60 g / L, and even more preferably 35 g / L to 45 g / L. When the lower limit of the content of component A is within the above range, the heat crack resistance of the sealing treatment film formed by sealing the anodized film is further improved. When the upper limit of the content of the organic acid is within the above range, the anodizing treatment can be carried out more satisfactorily on the surface of aluminum, etc.

[0032] ((B) Phosphorus Compound) The phosphorus compound (hereinafter also referred to as "component (B)") is not particularly limited, and for example, it is preferable to use a phosphorus-containing anionic chelate compound. The phosphorus-containing anionic chelate compound is not particularly limited, and known phosphorus-containing anionic chelate compounds can be used. Such phosphorus-containing anionic chelate compounds include those represented by the following general formula (1):

[0033] Examples of suitable anionic chelate compounds include phosphorus-containing anionic chelate compounds having at least one group represented by the following formula:

[0034] In the above general formula (1), * represents a bond.

[0035] As the phosphorus-containing anionic chelate compound having at least one group represented by the above general formula (1), a phosphorus-containing anionic chelate compound represented by the following general formula (2) can be used.

[0036]

[0037] In the general formula (2), n represents an integer of 1 or more and 10 or less. n is preferably an integer of 1 or more and 5 or less, more preferably an integer of 1 or more and 3 or less, even more preferably 1 or 2, and particularly preferably 2.

[0038] In the general formula (2), k, l, m, and o are the same or different and represent an integer of 1 to 10. k, l, m, and o are the same or different and represent an integer of 1 to 5, more preferably an integer of 1 to 3, still more preferably 1 or 2, and particularly preferably 1.

[0039] In the above general formula (2), it is preferable that n is 2 and k, l, m, and o are 1. That is, ethylenediaminetetra(methylenephosphonic acid) (EDTMP.8H) can be suitably used as the phosphorus-containing anionic chelate compound represented by the above general formula (2).

[0040] In the anodizing treatment solution of the present invention, a commercially available phosphorus-containing anionic chelating agent containing the phosphorus-containing anionic chelating compound represented by the general formula (2) can be used to supply the compound to the anodizing treatment solution. One such commercially available product is one containing ethylenediaminetetra(methylenephosphonic acid) (EDTMP·8H) and having a P content of 25.6% by mass.

[0041] As the phosphorus-containing anionic chelate compound having at least one group represented by the above general formula (1), a phosphorus-containing anionic chelate compound represented by the following general formula (3) can also be used.

[0042]

[0043] In the general formula (3), p and q are the same or different and represent an integer of 1 to 10. p and q are the same or different and represent an integer of 1 to 5, more preferably an integer of 1 to 3, and even more preferably 1 or 2.

[0044] In the above general formula (3), it is preferable that n is 1 and q is 2. That is, 2-phosphonobutane-1,2,4-tricarboxylic acid can be suitably used as the phosphorus-containing anionic chelate compound represented by the above general formula (3).

[0045] In the anodizing treatment solution of the present invention, a commercially available phosphorus-containing anionic chelating agent containing the phosphorus-containing anionic chelating compound represented by the general formula (3) can be used to supply the compound to the anodizing treatment solution. Such a commercially available product includes 2-phosphonobutane-1,2,4-tricarboxylic acid (C ２ H １１ O ９ ) and a P content of 5.7% by mass can be used.

[0046] The component (B) may be used alone or in combination of two or more.

[0047] The content of component B in the anodizing treatment solution is preferably 0.01 g / L to 100 g / L, more preferably 0.05 g / L to 80 g / L, even more preferably 0.1 g / L to 60 g / L, and particularly preferably 0.5 g / L to 50 g / L. By setting the lower limit of the component B content within the above range, the anodizing treatment can be carried out more satisfactorily on the surface of aluminum or the like. Furthermore, by setting the upper limit of the component B content within the above range, the heat crack resistance of the sealing treatment film formed by sealing the anodized film is further improved.

[0048] (Additives) The anodizing solution of the present invention may contain additives as components other than the above-mentioned components. Examples of such additives include ordinary additives used in anodizing solutions, such as preservatives and antifoaming agents.

[0049] The content of the additives in the anodizing treatment solution is not particularly limited as long as it does not inhibit the formation of an anodized film, and is preferably 10% by mass or less, more preferably 6% by mass or less, based on 100% by mass of the anodizing treatment solution. The lower limit of the content of the additives is not particularly limited, and may be 0%, 2%, or 5% by mass.

[0050] (Solvent) The anodizing treatment solution of the present invention is not particularly limited as long as it can dissolve or disperse the above-mentioned component (A), component (B), and additives added as needed, and examples thereof include water, alcohol, etc. Among these, water is preferred from the viewpoint of excellent safety.

[0051] The amount of solvent in the anodizing treatment solution is not particularly limited, and may be the balance between the contents of the above-mentioned component (A), component (B), and any additives that are added as needed.

[0052] 3. Anodizing Treatment Method The anodizing treatment method of the present invention is characterized by performing anodizing treatment using an anodizing treatment solution containing an organic acid and a phosphorus compound. The anodizing treatment method of the present invention is a method for anodizing aluminum or an aluminum alloy, and preferably includes (1) a step 1 of immersing the aluminum or aluminum alloy in an anodizing treatment solution to form an anodized film, wherein the anodizing treatment solution contains (A) at least one acid component selected from the group consisting of oxalic acid, malonic acid, malic acid, citric acid, adipic acid, L-tartaric acid, and hydrates thereof, and (B) phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, tripolyphosphoric acid, and a phosphorus-containing anionic chelate compound. The anodizing treatment method is described below by way of example.

[0053] In the anodizing method of the present invention, it is preferable that aluminum or an aluminum alloy described above in connection with the anodizing solution of the present invention is anodized.

[0054] (Step 1) Step 1 is a step of immersing aluminum or an aluminum alloy in an anodizing treatment solution to form an anodized film.

[0055] The method for immersing aluminum or the like in the anodizing treatment solution is not particularly limited, and aluminum or the like may be fixed as an anode for anodizing by a conventionally known method and then immersed in the anodizing treatment solution.

[0056] The anodizing treatment solution used in step 1 can be the anodizing treatment solution of the present invention described above.

[0057] The current density in step 1 was 0.1 A / dm ２ 5.0A / dm or more ２ Preferably, 0.5 A / dm or less ２ 4.0A / dm or more ２ More preferably, 1.0 A / dm or less ２ 3.0A / dm or more ２ The following is even more preferable. By setting the lower limit of the current density within the above range, a more sufficient anodic oxide film can be formed on the surface of aluminum, etc. Furthermore, by setting the upper limit of the constant current value within the above range, tanning of the surface of aluminum, etc. can be further suppressed.

[0058] The voltage in step 1 is preferably 40 V or more and 160 V or less, and more preferably 50 V or more and 90 V or less. When the lower limit of the voltage is in the above range, a more sufficient anodic oxide film can be formed on the surface of aluminum, etc. Furthermore, when the upper limit of the voltage is in the above range, tarnish on the surface of aluminum, etc. can be further suppressed.

[0059] The bath temperature of the anodizing treatment solution in step 1 is preferably 10° C. or higher and 50° C. or lower, and more preferably 20° C. or higher and 40° C. or lower. When the lower limit of the bath temperature is within the above range, a more sufficient anodized film can be formed on the surface of aluminum or the like. Furthermore, when the upper limit of the bath temperature is within the above range, evaporation of the solvent in the anodizing treatment solution can be further suppressed.

[0060] The electrolysis time in step 1 is preferably 30 minutes or more and 100 minutes or less, and more preferably 40 minutes or more and 50 minutes or less. When the lower limit of the electrolysis time is within the above range, a more sufficient anodized film can be formed on the surface of aluminum or the like. Furthermore, when the upper limit of the electrolysis time is within the above range, evaporation of the solvent in the anodizing treatment solution can be further suppressed.

[0061] The thickness of the anodic oxide film formed in step 1 is not particularly limited, but is preferably, for example, from 10 μm to 60 μm, and more preferably from 10 μm to 30 μm.

[0062] In step 1 described above, aluminum or the like is immersed in the anodizing treatment solution, and an anodized film is formed.

[0063] 4. Sealing Treatment Method In this specification, the sealing treatment method is a sealing treatment method for aluminum or an aluminum alloy, comprising: (1) Step 1 of immersing the aluminum or aluminum alloy in an anodizing treatment solution to form an anodized film; and (2) Step 2 of immersing the aluminum or aluminum alloy on which the anodized film has been formed in a sealing treatment solution to form a sealing treatment film, wherein the anodizing treatment solution contains an organic acid and a phosphorus compound. The sealing treatment method is preferably a sealing treatment method for aluminum or an aluminum alloy, and includes: (1) Step 1 of immersing the aluminum or aluminum alloy in an anodizing treatment solution to form an anodized film; and (2) Step 2 of immersing the aluminum or aluminum alloy, on which the anodized film has been formed, in a sealing treatment solution to form a sealing treatment film, wherein the anodizing treatment solution contains (A) at least one acid component selected from the group consisting of oxalic acid, malonic acid, malic acid, citric acid, adipic acid, L-tartaric acid, and hydrates thereof, and (B) at least one component selected from the group consisting of phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, tripolyphosphoric acid, and phosphorus-containing anionic chelate compounds.

[0064] In the sealing treatment method, the anodized film formed in step 1 described above in the anodizing treatment method of the present invention is subjected to sealing treatment in step 2 described below, thereby making it possible to perform sealing treatment on aluminum, etc. In the sealing treatment method, aluminum or an aluminum alloy described above in the anodizing treatment solution of the present invention can be used.

[0065] (Step 1) Step 1 is a step of forming an anodized film by immersing aluminum or an aluminum alloy in an anodizing solution. Step 1 is the same as step 1 in the anodizing method described above, and the anodizing solution used in Step 1 is also the same as the anodizing solution described in Step 1.

[0066] (Step 2) Step 2 is a step of immersing the aluminum or aluminum alloy on which the anodized film has been formed in a sealing solution to form a sealing film.

[0067] The sealing treatment liquid is not particularly limited, and any known sealing treatment liquid can be used, including sealing treatment liquids containing a metal salt, a complexing agent, and a pH adjuster.

[0068] The metal salt may be at least one metal salt selected from the group consisting of transition metal salts, alkali metal salts, and alkaline earth metal salts. The transition metal salts, alkali metal salts, and alkaline earth metal salts are not particularly limited, but water-soluble salts are preferred, such as acetates, carboxylates, sulfamates, sulfates, nitrates, and organic sulfonates. The metal salts may be used alone or in combination of two or more.

[0069] The content of the metal salt in the sealing solution is not particularly limited, but is preferably 1 g / L or more and 10 g / L or less. When the lower limit of the content of the sealing component is within the above range, the sealing ability of the anodized film of aluminum or the like is further improved. Furthermore, when the upper limit of the content of the sealing component is within the above range, the liquid stability of the sealing solution is further improved.

[0070] The sealing treatment liquid may contain a complexing agent. When the sealing treatment liquid contains a complexing agent as a sealing treatment component, the liquid stability of the sealing treatment liquid is further improved.

[0071] Examples of the complexing agent include chelating agents such as EDTA and EDTA-2Na or metal salts thereof; citric acid, tartaric acid, malic acid, lactic acid, gluconic acid or alkali metal salts thereof; amino acids such as glycine; amines such as ethylenediamine and alkylamine; other ammonium, pyrophosphate (salts), etc. The above complexing agents can be used alone or in combination of two or more.

[0072] The content of the complexing agent in the sealing treatment solution is preferably 0.01 g / L or more and 5.0 g / L or less. When the content of the complexing agent is within the above range, the liquid stability of the sealing treatment solution is further improved.

[0073] The sealing treatment solution may further contain a pH adjuster. The pH adjuster is not particularly limited, and any conventionally known pH adjuster can be used.

[0074] Examples of pH adjusters for adjusting the pore-sealing treatment solution to the acidic side include diluted aqueous solutions of acetic acid, sulfamic acid, sulfuric acid, nitric acid, organic sulfonic acid, etc. Among these, nitric acid and acetic acid are preferred because of their excellent pore-sealing performance.

[0075] Examples of pH adjusters for adjusting the pore-sealing treatment solution to the alkaline side include ammonia water, aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, etc. Among these, aqueous sodium hydroxide solution is preferred because of its excellent pore-sealing performance.

[0076] The pH adjusters may be used alone or in combination of two or more.

[0077] The sealing treatment solution may contain additive components such as an antifoaming agent, if necessary, to improve the sealing performance and practical use of the solution. Examples of additives include antifoaming agents such as nonionic surfactants.

[0078] The pH of the sealing treatment solution is preferably 3.0 or more and 7.0 or less. By adjusting the pH to this range, the sealing ability of the sealing treatment solution is further improved.

[0079] The sealing treatment liquid is preferably an aqueous solution containing the above-mentioned components.

[0080] As the sealing treatment solution, a commercially available product can be used, such as Topseal H-298 (trade name) manufactured by Okuno Chemical Industries Co., Ltd.

[0081] The bath temperature of the sealing treatment solution in step 2 is preferably 50° C. or higher and 100° C. or lower, and more preferably 70° C. or higher and 95° C. or lower. When the lower limit of the bath temperature is within the above range, the sealing ability of the anodized film of aluminum or the like is further improved. Furthermore, when the upper limit of the bath temperature is within the above range, the liquid stability of the sealing treatment solution is further improved.

[0082] The immersion time in step 2 is 1 minute / μm ２ More than 5 minutes / μm ２ Preferably, less than 2 min / μm ２ More than 3 minutes / μm ２ The following is more preferable. By setting the lower limit of the immersion time within the above range, the sealing ability of the anodized film of aluminum etc. is further improved. Furthermore, by setting the upper limit of the immersion time within the above range, the liquid stability of the sealing treatment solution is further improved.

[0083] By the above-described step 2, a sealing film can be formed on aluminum or the like on which an anodized film has been formed.

[0084] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0085] (Test Piece) As an aluminum alloy test piece, an A5052P plate material (50 mm x 100 mm, thickness 0.5 mm) was prepared.

[0086] (Anodizing Treatment) Anodizing treatment solutions with the compositions shown in Tables 1 to 3 were prepared as the anodizing treatment solutions used in the following tests. Specifically, each anodizing treatment solution was prepared by sequentially adding the compositions shown in Tables 1 to 3 to water as a solvent and stirring the mixture. In Tables 1 to 3, the component (B) used had the structure shown in Table 4.

[0087] The test pieces were anodized under the conditions shown in Tables 1 to 3. The anodized test pieces were then subjected to a sealing treatment using the following sealing solution under the following conditions to form a sealing film. Sealing solution: Topseal H-298 (manufactured by Okuno Chemical Industries Co., Ltd.) 40 ml / L Solution temperature: 90°C Electrolysis time: 30 minutes

[0088] The sealed film obtained by the above sealing treatment was left to stand in a dryer at 250° C. for 30 minutes to carry out a heat treatment.

[0089] The number of pores, pore diameter, and cell diameter of the anodized test specimens were measured by the following method. The amount of phosphorus adsorption (XPS "P") was also measured for the anodized film and the sealing film.

[0090] (Number of pores) The number of pores in the anodized film was determined by observing the surface of the anodized film with an FE-SEM microscope and randomly selecting pores of 1 μm ２ The measurement was carried out by counting the number of holes present in the range of 100 mm to 150 mm.

[0091] (Pore diameter) The pore diameter of the anodized film was measured by observing the surface of the anodized film with an FE-SEM microscope (manufactured by JEOL Ltd., JSM-7900F) and measuring an arbitrary pore diameter of 0.5 μm. ２ The diameters of the pores present in the range were measured, and the average value of 20 points was taken as the measured value of the pore diameter on the surface.

[0092] (Cell diameter) The cell diameter of the anodized film was measured by observing the surface of the anodized film with an FE-SEM microscope and measuring the cell diameter at an arbitrary interval of 0.5 μm. ２ The cell diameters of the cells present in the range were measured, and the average value of 10 points was taken as the measured value of the cell diameter on the surface.

[0093] (Phosphorus Adsorption Amount) The phosphorus adsorption amount on the surface of the anodized film (unsealed) and the sealed film (sealed) was measured by performing elemental analysis of the anodized film surface using an XPS measurement device (manufactured by ULVAC-PHI, Inc., product name PHI5000 VersaProbeIII) under the following conditions: X-ray setting: 100 μm, 25 W, 15 kV, pass energy: 55 eV, time per step: 50 ms, sputter mode: alternating, sputter setting: 2 kV 1 × 1.

[0094] The results are shown in Tables 1 to 3 and Figure 1. Also, Figures 2 to 7 show enlarged photographs of the FE-SEM images of Figure 1. Figure 2 shows enlarged SEM images of Comparative Example 2 (unsealed) at 200,000 magnifications, Figure 3 shows enlarged SEM images of Comparative Example 2 (unsealed) at 100,000 magnifications, and Figure 4 shows enlarged SEM images of Comparative Example 2 (sealed) at 100,000 magnifications. Also, Figure 5 shows enlarged SEM images of Example 3 (unsealed) at 200,000 magnifications, Figure 6 shows enlarged SEM images of Example 3 (unsealed) at 100,000 magnifications, and Figure 7 shows enlarged SEM images of Example 3 (sealed) at 100,000 magnifications. In Figure 1, the pore size and cell size are average values ​​measured at 20 points.

[0095] (Presence or absence of cracks) The sealing films formed by the method described above for anodizing were left to stand in a dryer at 130°C for 30 minutes, and heat treatment was performed three times. The surfaces of the sealing films after heat treatment were visually observed, and if no cracks were observed three times, it was evaluated as ``no cracks,'' and if cracks were observed even once, it was evaluated as ``cracks present.'' Figure 9 shows photographs of the surfaces of the sealing films of Comparative Example 2 and Example 3.

[0096] The results are shown in Tables 1 to 3.

[0097] It is clear from Tables 1 to 3 and Figures 1 to 7 that anodizing using an anodizing solution containing component (B) changes the structure of the anodized aluminum alloy and improves the heat crack resistance of the sealing film. Furthermore, from Figures 1 to 7, by observing the surface after sealing, no sealing inhibition due to the use of an anodizing solution containing component (B) was confirmed. Therefore, it was found that the improvement in heat crack resistance is not due to the inhibition of sealing caused by the use of component (B).

[0098] 9 also shows that Example 3, in which anodizing treatment was performed using an anodizing treatment solution containing component (B), suppressed the occurrence of heat-resistant cracks in the sealing treatment film, demonstrating excellent heat-cracking resistance. In contrast, Comparative Example 2, in which anodizing treatment was performed using an anodizing treatment solution not containing component (B), clearly showed cracks in the sealing treatment film, demonstrating poor heat-cracking resistance.

[0099] (Phosphoric Acid-Chromic Acid Aqueous Solution Immersion Test) The acid resistance of the sealed films obtained by sealing the anodized films prepared in the Examples and Comparative Examples was evaluated using a measurement method in accordance with the phosphoric acid-chromic acid aqueous solution immersion test of JIS H-8683-2, with n=2 and evaluation performed one day after sealing.

[0100] The results are shown in Tables 1 to 3.

[0101] The results in Tables 1 to 3 show that the examples using an anodizing treatment solution containing oxalic acid and component (B) exhibited good sealing properties. Furthermore, when phosphoric acid was added to the oxalic acid bath (Comparative Example 2) (Examples 22 to 24), the weight loss was 2.58 mg / dm ２ to 2.51 mg / dm ２ 4.50mg / dm or more ２ Although the sealing degree was slightly lower, it was found that the performance was equivalent. This indicates that the addition of a small amount of phosphoric acid to the oxalic acid bath does not inhibit sealing. It was also found that the phosphate coating (Comparative Example 3) exhibited a significantly lower sealing degree. This is thought to be due to the formation of aluminum phosphate, which inhibits the hydration reaction of aluminum and the like. In Comparative Example 3, the reason that cracks did not occur after the heat treatment at 130°C is because the sealing treatment of the phosphate coating was insufficient.

[0102] (Marker test) The sealing degree of the sealed films obtained by sealing the anodized films prepared in the Examples and Comparative Examples was evaluated by a marker test. Specifically, a dot was drawn on the surface of the sealed films prepared in the Examples and Comparative Examples with a marker, and the film was wiped five times with IPA to evaluate whether the marker had disappeared. A mark that had completely disappeared was marked with a circle, and a mark that showed residual marker was marked with an X.

[0103] The results are shown in Tables 1 to 3.

[0104] The results in Tables 1 to 3 show that the sealing treatment films of the Examples, Comparative Examples 1 and 2, which used a bath containing oxalic acid, exhibited good marker removal properties. It was found that the phosphate coating (Comparative Example 3) exhibited poor marker removal properties due to the inhibition of sealing by phosphorus.

[0105]

[0106]

[0107]

[0108]

[0109] To confirm the presence of phosphorus in the surface layer of the anodized film, XPS elemental analysis was performed on the anodized film surface of the unsealed test specimens of Example 3 and Comparative Example 2. XPS elemental analysis was performed using an XPS measurement device (manufactured by ULVAC-PHI, Inc., product name PHI5000 VersaProbeIII) under the following conditions: X-ray settings: 100 μ, 25 W, 15 kV, pass energy: 55 eV, time per step: 50 ms, sputter mode: alternating, sputter setting: 2 kV 1×1.

[0110] The results are shown in Table 5 and FIG.

[0111]

[0112] As can be seen from Table 5 and Fig. 8, a peak derived from elemental phosphorus was observed in the anodized film of Example 1, which contained a phosphorus-containing anionic chelate compound. This indicates that the adhesion of a phosphorus-containing anionic chelate compound to the surface of an anodized film enables the formation of an anodized film having a structure capable of forming a sealed film with excellent heat crack resistance, as shown in Figs. 1, 5, and 6.

Claims

1. An anodic oxide coating characterized in that the amount of phosphorus adsorbed on the surface after sealing treatment is 0.1 at% or more and 4.0 at% or less.

2. The anodic oxide coating according to claim 1, wherein the amount of phosphorus adsorbed on the surface after sealing is 0.1 at % or more and 3.0 at % or less.

3. Number of pores on the surface: 50 / μm ２ More than 120 pieces / μm ２ An anodic oxide film characterized by the following:

4. An anodic oxide film characterized by a surface pore diameter of 38 nm or more.

5. An anodic oxide film characterized by a surface cell diameter of 89 nm or more.

6. An anodic oxide film formed using an anodizing treatment solution characterized by containing an organic acid and a phosphorus compound.

7. The anodic oxide film according to any one of claims 1 to 6, wherein the anodic oxide film is subjected to a sealing treatment after anodizing.

8. An anodizing solution characterized by containing an organic acid and a phosphorus compound.

9. An anodizing method characterized in that the anodizing treatment is carried out using an anodizing treatment solution containing an organic acid and a phosphorus compound.

10. An anodizing method characterized by carrying out an anodizing treatment using an anodizing treatment solution containing an organic acid and a phosphorus compound, and then carrying out a sealing treatment.

11. An industrial product having the anodic oxide coating according to any one of claims 1 to 6.

12. An industrial product having the anodic oxide coating according to claim 7.

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