JP5728685B2 - Black chemical conversion film forming treatment liquid, method of treating metal member thereby, and treated metal member - Google Patents

Description

  The present invention relates to a surface treatment liquid for stably forming a chromium-free black film having a uniform appearance excellent in corrosion resistance on a metal member, particularly an electrolytic galvanized film, a surface treatment method thereof, and a surface. The present invention relates to a surface treatment method including an overcoat treatment after the treatment. Moreover, it is related with the member obtained by these surface treatment methods.

  For the purpose of improving the corrosion resistance, the metal member may be subjected to a treatment for forming a rust preventive film by contacting with a chemical conversion treatment solution containing hexavalent chromium or trivalent chromium. However, since hexavalent chromium is highly harmful to the human body and the environment, its use has been greatly restricted in recent years. Furthermore, with regard to the rust prevention method using trivalent chromium, which appeared as an alternative to hexavalent chromium, there is a concern that hexavalent chromium will be generated from trivalent chromium, and it is completely chromium-free from the viewpoint of more active green procurement. Processing has come to be required.

  The treatment for forming a black rust preventive film using a chemical conversion treatment solution containing trivalent chromium is made of, for example, Japanese Patent Application Laid-Open No. 2003-268562 consisting of trivalent chromium, an inorganic acid, cobalt and / or nickel, and a chelating agent. Japanese Patent Application Laid-Open No. 2005-206872 discloses a black film forming process comprising a compound of trivalent chromium, an inorganic acid and sulfur. Moreover, the method currently generally performed which obtains a black rust prevention film | membrane by a trivalent chromium chemical conversion treatment with respect to a zinc-type plating member is also disclosed by the said literature, and is based on inorganic acids, such as nitric acid or a sulfuric acid. In this method, activation is performed, black film forming treatment is performed once after washing with water, finishing treatment is performed after washing with water, and drying is performed.

  As for the treatment for forming a colored anticorrosive film by chromium-free treatment, Japanese Patent Application Laid-Open No. 2004-232047 and Japanese Patent Application Laid-Open No. 2008-174807 are used for magnesium and aluminum members, and Japanese Patent Application Laid-Open No. 2008-133502 for zinc-based members. JP, 2007-023353, JP 2010-031332, JP 2009-270137, JP 2010-013677, etc., all of which disclose a white chromium-free rust preventive film forming method. ing. However, there are few disclosure examples of the black chromium-free rust preventive film forming method.

  It is technically difficult to form a complete chromium-free black rust preventive film as compared with a white rust preventive film. The reason for this is that (1) the required level of appearance is higher for black parts, and (2) the corrosion resistance is reduced by the components necessary for producing black. However, since black parts have great value both in terms of rust prevention function and decorative properties, and the economic value is very high, forming a complete chrome-free black rust prevention film is very technical and economical. It has meaning.

  Japanese Patent Application Laid-Open No. 2005-232504 discloses a method of forming an organic resin film after being immersed in a black chemical conversion treatment solution composed of vanadium, aluminum, and ammonium ions and further treated with tannic acid. . However, compared with the current black processing using general trivalent chromium, the number of processing is large, and it is difficult to incorporate it into the current line unless it is performed even by adding a line.

  Japanese Patent Application Laid-Open No. 2006-328883 discloses that a first black chemical conversion film is immersed in a first black chemical conversion film treatment solution containing vanadium and a sulfur compound as essential components and further containing at least one selected from cobalt, nickel, titanium, and tungsten. Disclosed is a method for forming a black chemical conversion film comprising a second treatment liquid that has a larger ionization tendency than metal ions in the treatment liquid and does not contain tannic acid, and a third treatment liquid that contains tannic acid and does not contain the metal ions. ing. However, the number of processing is large and it is difficult to incorporate it into the current line. Also, in this method, forming three or more layers is a very important point for exerting the performance of the film. As a result of intensive studies by researchers, it was found that the corrosion resistance in the case where a film was not properly formed was remarkably reduced in addition to the normal corrosion resistance with only two layers. This was a film in which the presence of the third and subsequent layers has great significance. In addition, when Example 1 was actually carried out, a blackish appearance was obtained, but it was difficult to obtain blackness by changing the conditions a little, and it was found that the film remained a problem in the application range. It was.

  Japanese Patent Application Laid-Open No. 2008-214744 discloses a method of forming a black film using aluminum, antimony, phosphoric acid, and a thio compound, but the nitric acid activity and the first chemical conversion film forming treatment are simultaneously performed (black metal activity). Is a two-stage process that improves the corrosion resistance by performing a conversion film formation process with a tannic acid solution on the black conversion film after washing with water, and additionally requires an overcoat final finishing process. But unless it is done, it is difficult to incorporate it into the current line.

JP 2003-268562 A JP 2005-206872 A JP 2004-232047 A JP 2008-174807 A JP 2008-133502 A Japanese Patent Laid-Open No. 2007-023353 JP 2010-031332 A JP 2009-270137 A JP 2010-013677 A JP 2005-232504 A JP 2006-328883 A JP 2008-214744 A

  An object of the present invention is to provide a uniform black appearance and sufficient corrosion resistance to a member having a metal surface, particularly a member plated with zinc or zinc alloy (hereinafter generally referred to as a zinc-based plated member) regardless of the shape of the plated member. It is an object to provide a surface treatment method and a surface treatment system for stably forming a chromium-free and phosphoric acid-free chemical conversion film having the above. Another object of the present invention is to provide a method capable of using the same equipment as the conventional trivalent chromium black chemical conversion film forming treatment.

  As a result of intensive studies by the present inventors, it was confirmed that a chemical conversion film having a substantially single metal on the surface layer was formed by immersing a zinc-based plating member in an aqueous solution of a vanadium compound and an organic sulfur compound. It was.

  Since white rust is an oxide of zinc, the absence of zinc in the surface layer means that white rust does not occur until a layer containing zinc is reached. Since a black component is mixed in the zinc-free layer, it is considered that a film having a black appearance and having corrosion resistance more than expected is formed. Furthermore, it was found that a black rust preventive film having an excellent corrosion resistance and appearance equivalent to that of the existing trivalent chromium black chemical conversion film treatment can be formed by performing a finishing treatment.

  The black color of the film is due to the reaction with the organic sulfur compound alone or with the galvanized film, and the corrosion resistance is easily exhibited by not containing zinc in the surface layer of the chemical conversion film. That is, the coating of the present invention is excellent in that a coating having a black appearance and corrosion resistance can be formed by a single chemical conversion treatment except for the finishing treatment.

  The black chemical conversion film forming treatment liquid not only does not contain chromium, but also phosphorus, fluoride, and the like are not essential components. Therefore, when these are not contained, the waste water treatment is further facilitated. From the above points, there is an advantage that the environmental load can be kept low. Since the treatment procedure is the same as the conventional black chemical conversion film forming treatment using trivalent chromium, the existing equipment performing these treatments can be used as it is, and the equipment investment can be suppressed at the time of switching.

  In one embodiment, the treatment liquid according to the present invention is provided as an aqueous solution of each component. Although the processed object is the whole member with a metal surface, the thing of the zinc-type metal surface formed by electrolytic plating is preferable. There are no limitations on the type of electrolytic plating bath and the shape of the plated member, but a conductive salt made of an alkali hydroxide or an inorganic hydrochloride is preferable in terms of excellent appearance and corrosion resistance even in a member having a complicated shape. The surface treatment procedure is the same as the conventional black chemical conversion film forming treatment with trivalent chromium.

  In one embodiment, the surface treatment liquid of the present invention contains at least one selected from the group consisting of vanadium group element compounds, organic sulfur compounds, and chlorine ions, fluorine ions, nitrate ions, sulfate ions, and acetate ions, and It is a metal surface treatment liquid that does not contain chromium.

  Among the components of the chemical conversion treatment liquid, the vanadium compound is a basic component for forming a protective film and imparting corrosion resistance to a member having a metal surface. The organic sulfur compound reacts with the vanadium chemical conversion film to form a black component.

The source of vanadium compound is not critical, for example, vanadium chloride (VCl _2, VCl _3, and VCl _4), dichloride vanadyl (VOCl _2), vanadium bromide (VBr _2, VBr _3), iodide vanadium (VI ₂ , VI ₃ ), vanadium sulfate (VSO ₄ , V ₂ (SO ₄ ) ₃ ), vanadyl sulfate (VOSO ₄ ), vanadium nitrate (V (NO ₃ ) ₂ , V (NO ₃ ) ₃ ), vanadium pentoxide ( V ₂ O ₅ ), vanadate (H ₃ VO ₄ ), potassium orthovanadate (K ₃ VO ₄ ), sodium orthovanadate (Na ₃ VO ₄ ), lithium orthovanadate (Li ₃ VO ₄ ) potassium metavanadate (KVO _3), sodium metavanadate (NaVO _3), lithium metavanadate (LiVO _3), ammonium metavanadate (NH ₄ VO _3), And the like. More preferably, a compound in which the oxidation number of vanadium is between 4 and 5 is contained. This is because pentavalent vanadium may cause precipitation at a high concentration. The total concentration of these compounds is preferably 1 to 100 g / L, more preferably 3 to 60 g / L. If it is 1 g / L or less, a sufficient film may not be formed. If it is 100 g / L or more, precipitation may occur when the treatment is continued.

  Specific sources of organic sulfur compounds include thiourea, allyl thiourea, ethylene thiourea, diethyl thiourea, diphenyl thiourea, tolyl thiourea, guanyl thiourea and acetyl thiourea, mercaptoethanol, mercaptohypoxatin, mercapto Mercaptos such as benzimidazole and mercaptobenzthiazole, thiocyanic acid and its salts, amino compounds such as aminothiazole, and commercial products include Nouchira TMU, Noxeller TBT, Noxeller NS-P, Nocrack TBTU and Nocrack of Ouchi Shinsei Chemical Co., Ltd. NS-10N, Accelerator 22-R, Accelerator 22-S, Accelerator BUR-F, Accelerator CZ, Accelerator EUR-H, Accelerator LUR, Accelerator TET, Accelerator TP, etc. of Kawaguchi Chemical Industry Co., Ltd. are available. Further, thiocarboxylic acids such as thioformic acid and thioacetic acid and salts thereof, dithiocarboxylic acids such as dithioformic acid, dithioacetic acid and dithiocarbamic acid and salts thereof, thiomalic acid, thioglycolic acid, thiodiglycolic acid, dithiodiglycolic acid, thio Carboxylic acids containing sulfur, such as salicylic acid, dicarboxylic acids and salts thereof are useful because they have a skeleton similar to chelating agents. Of these, thioureas, thiocarboxylic acids, dithiocarboxylic acids, sulfur-containing carboxylic acids, dicarboxylic acids and salts thereof are particularly useful, and disulfide group-containing polycarboxylic acids and salts thereof are more preferable. The concentration of the organic sulfur compound is preferably 2 to 100 g / L, and more preferably 5 to 40 g / L. It is not sufficiently blackened at 2 g / L or less. A normal film cannot be formed at 100 g / L or more.

  For at least one selected from the group consisting of chlorine ions, fluorine ions, nitrate ions, sulfate ions, acetate ions or borate ions, the effective ions differ depending on the type of substrate, but for zinc-based metal surfaces If it contains nitrate ions, it is easy to obtain a film having a good appearance, and nitrate ions are considered to greatly contribute to the improvement of the uniformity and film forming property of the vanadium film. The source of various ions is preferably an alkali metal salt or an alkaline earth metal salt in addition to the acid form, but other metal salts and ammonium salts can also be used without any limitation. The concentration of nitrate ions is preferably 0.1 g / L to 50 g / L, more preferably 1 to 10 g / L. If it is 0.1 g / L or less, there is a strong possibility that a non-uniform film thickness and a film with insufficient film thickness will be formed. Uniformity and film-forming properties of aluminum and magnesium-based metal surfaces by containing at least one selected from the group consisting of boron, silicon, zirconium, titanium and hafnium fluorine compound ions, and fluoride ions Will improve.

  Further, the surface treatment liquid may contain at least one selected from the group consisting of Fe, Mg, Zn, Ca, Y, La, Ce, Mo, Al, Zr, Mn, Ni, and Co. These components are considered to have the effect of precipitating together with the above-mentioned basic components for film formation or making the film denser, and contribute to appearance and corrosion resistance. These supply sources are not limited as long as they are water-soluble compounds, but nitrates, sulfates or chlorides are preferable. Moreover, it is preferable that the anionic acid forming an oxygen acid is an alkali metal salt or an ammonium salt, but there is no limitation. The concentration is preferably in the range of 0.1 to 50 g / L for one kind of ion. If it is 0.1 g / L or less, the effect is not sufficiently exhibited, and if it is 50 g / L or more, the treatment liquid may be precipitated.

In addition to the above components, a silicon compound can be contained. As a supply source of the silicon compound, water-dispersible colloidal silica can be used in addition to various water-soluble silicates.
As colloidal silica, for example, Snowtex (trademark) series (Nissan Chemical Industry Co., Ltd.), Adelite (trademark) AT series (corporation ADEKA), Silica Doll (trademark) series (Nippon Chemical Industry Co., Ltd.), Cataloid (trademark) series (JGC Catalysts & Chemicals Co., Ltd.), etc. are mentioned, but it is not limited to these. The average particle diameter of colloidal silica is preferably 50 nm or less, and the concentration of the silicon compound is preferably 50 g / L or less. When the average particle size is 50 nm or more, it becomes powdery and has a rough appearance. When the concentration of the silicon compound is 50 g / L or more, there is a strong possibility that precipitation occurs in the treatment liquid.

  Furthermore, in addition to the above components, an organic acid containing no sulfur can be contained in the molecule in order to improve the uniformity of the film appearance. Carboxylic acid is particularly effective, and the effect is great when glycolic acid, citric acid, and malonic acid are added, but it is not limited to these. The addition amount is 0.1 to 50 g / L, more preferably 1 to 10 g / L. If it is 0.1 g / L or less, the effect is not sufficiently exhibited, and if it is 50 g / L or more, there is a strong possibility that the formation of the film is hindered.

  As immersion conditions, a temperature of 10 to 50 ° C. and a pH of 1.0 to 3.0 are preferable, and a temperature of 20 to 40 ° C. and a pH of 1.5 to 2.5 are more preferable. At low temperatures, a sufficient film is not formed, and at high temperatures, the appearance tends to become cloudy and the workability is impaired. At low pH, excessive reaction occurs and a sufficient film is not formed. At high pH, it is difficult to form a film due to insufficient reaction, and precipitation tends to occur when the treatment liquid contains Ti or Zr. The immersion time is in the range of 10 to 120 seconds, preferably 30 to 90 seconds. If the immersion time is less than 10 seconds, there is a high possibility that a sufficient film thickness cannot be obtained. Soaking for 120 seconds or more is less effective, and rather causes a decrease in productivity. Moreover, in order to form a film | membrane uniformly, it is preferable that there is stirring, and it is preferable to wash a to-be-processed object after chemical conversion treatment.

  After the chemical conversion treatment, washing with water, and before or after drying, coating with an inorganic, organic or organic-inorganic composite further improves the corrosion resistance. Examples of inorganic overcoats include silica-based and phosphoric acid-based overcoats, but other overcoats are also possible. The organic overcoat is not particularly limited with respect to the coating material and the resin type, and can be applied to an aqueous overcoat or other than an aqueous overcoat. For example, polyethylene, polyvinyl chloride, polystyrene, polypropylene, acrylic resin, methacrylic resin, polycarbonate, polyamide, polyacetal, fluororesin, urea resin, phenol resin, unsaturated polyester resin, polyurethane, alkyd resin, epoxy resin, melamine resin, etc. Although a film | membrane is mentioned, it is not limited to these. Further, overcoating may be performed immediately after the surface treatment according to the present invention, but it is also effective if it is performed after drying and after processing such as pressing and bending, and it is also effective to perform the coating several times. The method of overcoat is not particularly limited, and various methods such as coating, immersion coating, electrostatic coating, electrodeposition coating, and powder coating are possible. Among the above-mentioned overcoats, in particular, when a phosphate film formation treatment is performed and a phosphate film is formed on the surface of the chemical conversion film, the corrosion resistance is greatly improved. This was not seen in the trivalent chromium black chemical conversion film treatment.

  Specific examples of the treatment liquid of the present invention include vanadium compounds 1 to 100 g / L, organic compounds 1 to 100 g / L, acid ions such as nitrate ions 0.1 g / L to 50 g / L, and in some cases, Fe, Mg Zn, Ca, Y, La, Ce, Mo, Al, Zr, Mn, Ni, Co. One or more metal compounds (per type) of 0.1 to 50 g / L, optionally further silicon compound 0.1 An acidic reactive chemical conversion treatment solution containing ˜50 g / L. Using this treatment solution, a galvanized member and a zinc alloy plated (particularly zinc-iron alloy plated) member have a temperature of 10 to 50 ° C. and a pH of 1; Inorganic, organic or organic-inorganic composite coating on the non-chromium black chemical conversion coating film after immersion in a chemical conversion treatment solution of 0 to 3.0 for 10 to 120 seconds or further washing the object to be processed with water Or forming these multilayer coating film.

  Hereinafter, the present invention will be described with reference to examples and comparative examples. In the test, the test piece was subjected to an appropriate pretreatment such as nitric acid immersion, and then treated according to each example shown in the table below. The test piece used was an iron bolt or aluminum or magnesium bolt subjected to either zinc plating (Zn) or zinc-iron alloy plating (Zn-Fe). The average thickness of the plating was 10 to 12 μm. In addition, pH adjustment of the process liquid was performed using nitric acid. Appearance was evaluated visually by comprehensively judging gloss, unevenness, haze, blackness, and the like. Corrosion resistance was evaluated by performing a salt spray test according to JIS Z 2371 and showing the time when white rust was generated by 5%.

(Examples 3 to 17, 20)
The vanadium compound used was vanadium chloride, and the test was performed while changing the plating as a base, the concentration of each component, and the finishing treatment. However, in Examples 12 and 13, vanadium fluoride was further added because the base materials were different. The results are shown in Table 1. Moreover, the column of the corrosion resistance of Table 1 is the case where the top is not finished and the bottom is finished.

(Examples 2, 18, 19, 21-36)
The vanadium compound to be used was vanadium sulfate, and the test was performed by changing the concentration of each component, the conversion film treatment conditions, and the finishing treatment. The results are shown in Table 1.

Example 1
The test was conducted with the vanadium compound used as potassium metavanadate. The results are shown in Table 1.

(Comparative Example 1)
When the thing except the thiomalic acid was created and processed from Example 8, the corrosion resistance equivalent to Example 8 was obtained, but the black color tone was not obtained.

(Comparative Example 2)
When a product obtained by removing vanadium chloride from Example 8 was prepared and processed, a black appearance was obtained, but white rust generation time was 8 hours without finishing and 24 hours with finishing.

(Comparative Examples 3 and 4)
As a metal compound containing a blackening metal, ammonium metavanadate and cobalt sulfate, the first blackening treatment liquid of the composition for forming a black rust preventive film described in JP-A-2006-328484 (Comparative Example 3: V10 g / L, Co 10 g / L, Comparative Example 4: V 10 g / L, Co 5 g / L, pH 3.0) was adjusted with nitric acid. The test piece was immersed in this first blackening treatment solution with 1 g / L of a sulfur compound (thioglycolic acid) at 30 ° C. for 60 seconds to form a second rust preventive film, and then washed with water. Furthermore, after forming a third rust preventive film by immersing in a third treatment liquid (tannic acid content 3.0 g / L) of the black rust preventive film forming composition at 25 ° C. for 60 seconds, It was washed with water and dried at 60 ° C. for 10 minutes to obtain a black rust-proof metal. The appearance was good, and as a result of the corrosion resistance test, white rust occurred in 96 hours.

(Comparative Examples 5 and 6)
In the chemical conversion treatments shown in Comparative Examples 3 and 4, those in which the process of immersing in the third treatment liquid was omitted were referred to as Comparative Examples 5 and 6, respectively. Although the appearance was good, white rust was generated in 24 hours as a result of the corrosion resistance test.

Claims (13)

(A) a vanadium compound, (B) an organic sulfur compound, and (C) at least one selected from the group consisting of chlorine ion, fluorine ion, nitrate ion, sulfate ion, acetate ion and boron ion, and (D) chromium And the concentration of the organic sulfur compound is 2 g / L or more .   2. The black chemical conversion coating solution according to claim 1, wherein the organic sulfur compound contains two or more of any one or more of a sulfur atom and a carboxyl group in one molecule.   The black chemical conversion film production treatment liquid according to claim 1 or 2 in which said organic sulfur compound contains a disulfide group in one molecule.   The black chemical conversion film production processing liquid whose organic sulfur compound according to claim 1 is carbothioic acid or its salt.   The black chemical conversion film production processing liquid whose organic sulfur compound according to claim 1 is thiourea. Furthermore, the black of any one of Claims 1-5 containing 1 or more types of metals chosen from Fe, Mg, Zn, Ca, Y, La, Ce, Mo, Al, Zr, Mn, Ni, and Co. Chemical conversion coating solution. Furthermore, the black chemical conversion film production | generation process liquid of any one of Claims 1-6 containing a silicon compound. Black conversion layer generating process solution according to any one of claims 1 to 7, further comprising an organic acid or a salt thereof contains no sulfur in the molecule. 9. The black chemical conversion coating solution according to claim 8, wherein the organic acid is a divalent or higher polyvalent carboxylic acid, oxycarboxylic acid or a salt thereof. The method to form a chromium-free black chemical conversion film by immersing a metal member in the black chemical conversion film production treatment liquid according to any one of claims 1 to 9 . The method according to claim 10 , wherein the metal member is zinc or zinc iron alloy plating. 12. A method for forming a film, comprising performing an inorganic, organic or organic-inorganic composite coating treatment once or a plurality of times after the method according to claim 10 or 11 is carried out. The metal member which gave the method of any one of Claims 10-12 .