JP2009041092A - Chemical treatment liquid for galvanizing or galvannealing film, and method for forming corrosion protection coating using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical treatment liquid capable of forming a corrosion protection coating in which satisfactory corrosion protection performance can be obtained with high reproducibility and high uniformity, and variation is hard to occur in the corrosion protection performance. <P>SOLUTION: Disclosed is a chemical treatment liquid for a galvanizing or galvannealing coating which does not substantially comprise hexavalent chromium ions, and at least comprises the following (A) to (F): (A) trivalent chromium ions; (B) nitric acid ions; (C) one or more of ≤8C aliphatic polycarboxylic acids other than carbon which compose a carboxyl group; (D) one or more metal ions selected from iron, cobalt and nickel; (E) zinc ions; and (F) one or more 1 to 6C aliphatic alcohols. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for obtaining a plating film excellent in anticorrosion performance, and more particularly, to a method for obtaining a plating film excellent in anticorrosion performance by chemical conversion treatment of zinc or a zinc alloy plating film with a specific chemical conversion treatment solution. .

A method of applying chromate treatment to a zinc or zinc alloy plating film using a solution containing hexavalent chromium to improve rust prevention performance has been widely used. Although there are examples in which zinc-iron alloy plating or zinc-nickel alloy plating is used as a part of the plating film, most of them were a chromate treatment on a plating film of zinc alone.
In recent years, in order to avoid the use of hexavalent chromium, which may adversely affect the human body and the environment, chromium-free chemical conversion treatment and methods for chromate treatment using trivalent chromium have been studied. Are also being used. However, the present situation is that a method for obtaining a plating film capable of obtaining an anticorrosion performance comparable to the treatment with hexavalent chromium has not been completed in spite of active studies as exemplified below.

As a method for obtaining a hexavalent chromium-free anticorrosive film, a method using a chromium-free chemical conversion treatment using a compound such as cerium, molybdenum, or manganese has been studied, but an anticorrosion performance comparable to a treatment containing chromium is inevitably obtained. Therefore, there is no choice but to use a chemical conversion treatment using a trivalent chromium compound.
Regarding the chemical conversion treatment using trivalent chromium, the following techniques are disclosed.

Japanese Patent Application Laid-Open No. 2003-166074 discloses a treatment solution for forming a chromate film on zinc and zinc alloy plating containing trivalent chromium and cobalt oxalate ions.
Japanese Patent Application Laid-Open No. 2003-166075 discloses a treatment solution for forming a chromate film containing a silicon compound, trivalent chromium, and cobalt oxalate ions.
Japanese Patent Application Laid-Open No. 2003-268562 discloses a solution for forming a black hexavalent chromium-free chemical conversion film containing nitrate ions, trivalent chromium, cobalt or nickel ions, and a chelating agent. Further, chromium phosphate is used as a source of trivalent chromium, oxalic acid, malonic acid, succinic acid, etc. can be used as the chelating agent, and silicon, iron, titanium, zirconium, tungsten, vanadium, molybdenum A solution containing one or more metal ions selected from the group consisting of strontium, niobium, tantalum, manganese, calcium, barium, magnesium and aluminum is disclosed.
JP-A-2003-313675 discloses (A) trivalent chromium ions, (B) Mo, W, Ti, Zr, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, alkaline earth metal One or more of the group consisting of (C) Ni, Pd, Pt, Sc, Y, V, Nb, Ta, Cu, Ag, Au, one or more of the group consisting of (D) chlorine, fluorine Forming a rust preventive film with a liquid composition containing one or more members selected from the group consisting of sulfate ions and nitrate ions, and (E) one selected from the group consisting of Si, Al and organic acids. And a method for forming an anticorrosive film on a metal.
In JP-A-2005-126696, (a) a step of depositing a zinc-nickel alloy plating having a nickel eutectoid rate of 8% or less on a substrate, and (b) a deposited zinc-nickel alloy plating at least with an inorganic mineral acid. On the zinc-nickel alloy plating, comprising: a step of immersing in an activation liquid containing one kind and having a pH of 1 or less; and (c) treating the obtained zinc-nickel alloy plating with a trivalent chromate liquid. A method of forming a hexavalent chromium-free corrosion resistant coating is disclosed. Furthermore, a method using a solution containing one or more selected from the group consisting of zinc, cobalt and silicon is disclosed.
Japanese Patent Application Laid-Open No. 2005-126797 discloses a trivalent chromate solution for zinc-nickel alloy plating containing a nitrate ion of 0.01 mol / liter or more and a zinc compound and having a pH in the range of 1.5 to 5.5. A group consisting of a trivalent chromate solution further containing one or more of a cobalt compound and a silicon compound in the solution, and further comprising a monocarboxylic acid, dicarboxylic acid, tricarboxylic acid, hydroxycarboxylic acid, aminocarboxylic acid and salts thereof A trivalent chromate solution containing at least one selected from the group consisting of 1 and 2 is disclosed.
JP 2003-166074 A Japanese Patent Laid-Open No. 2003-166075 JP 2003-268562 A JP 2005-126696 A Japanese Patent Laid-Open No. 2005-126797

  However, as described above, the actual situation is that the anticorrosion performance comparable to the chromate treatment using hexavalent chromium on the galvanized film cannot be obtained. In particular, the chemical conversion treatment using trivalent chromium has problems in reproducibility and uniformity as compared with the case of using hexavalent chromium, and even under processing conditions having good anticorrosion performance in a beaker level test. For example, in an evaluation test such as a salt spray test, there have been problems such as poor reproducibility of results and frequent variations in anticorrosion performance between samples.

  Therefore, it is an object of the present invention to develop a chemical conversion treatment solution for zinc or zinc alloy plating film capable of forming an anticorrosion film that can provide good anticorrosion performance with good reproducibility and uniformity and hardly causes variations in the anticorrosion performance. One. Another object of the present invention is to develop a method for forming a highly anticorrosive film using such a chemical conversion treatment solution.

The present inventor contains a combination of at least two or more kinds of specific metal ions, contains an aliphatic polycarboxylic acid as a complexing agent for stabilizing these metal ions in addition to nitrate ions, and further contains an alcohol as an essential component. By treating zinc or zinc alloy plating film, especially zinc-nickel alloy plating film, with a trivalent chromium chemical conversion treatment solution, the uniformity of chemical conversion film formation is significantly improved and an excellent anticorrosive film is created. As a result, the present invention has been completed.
The anticorrosive effect by adding alcohol is synergistically obtained in combination with other essential components. That is, the anticorrosive effect remarkably excellent compared with the case where any of other essential components is missing can be obtained. It can be said that the technical contribution of the present invention resides in the unique combination of a plurality of specific components.

That is, the subject of the present invention does not substantially contain hexavalent chromium ions, and at least the following (A) to (F),
(A) trivalent chromium ion,
(B) nitrate ion,
(C) One or more aliphatic polycarboxylic acids having 8 or less carbon atoms other than carbon constituting the carboxyl group,
(D) One or more kinds of metal ions selected from iron, cobalt, and nickel,
(E) zinc ion,
(F) one or more aliphatic alcohols having 1 to 6 carbon atoms,
It contains a chemical conversion treatment solution for zinc or zinc alloy plating film.
Each of the above (A) to (E) is a known component as a chromate treatment solution using trivalent chromium, but (F) one or two or more kinds of aliphatic alcohols having 1 to 6 carbon atoms (A ) To (E), the uniformity of the formation of the chemical conversion film is remarkably improved, and an excellent anticorrosion film is obtained.

In one embodiment of the chemical conversion liquid according to the present invention,
0.01 to 20 g / L (A),
(B) 1-100 g / L,
0.1 to 50 g / L in total with (C) as the acid radical,
(D) and (E) in total 0.01 to 100 g / L
0.1 to 100 g / L in total for (F)
contains.

  In another embodiment of the chemical conversion liquid according to the present invention, the (F) alcohol is selected from methanol, ethanol, propanol and butanol.

  In another embodiment of the chemical conversion liquid according to the present invention, the concentration of the (F) alcohol is 3 g / L or more.

  In still another embodiment of the chemical conversion treatment liquid according to the present invention, (G) colloidal silica is further contained.

  In still another embodiment of the chemical conversion treatment liquid according to the present invention, the (C) aliphatic polycarboxylic acid is oxalic acid.

  Another subject of the present invention is a method for forming an anticorrosive film comprising bringing a zinc or zinc alloy plating film applied on a substrate into contact with the chemical conversion solution.

  In one embodiment of the method for forming an anticorrosion film according to the present invention, the plating film is a zinc-nickel alloy plating film.

  In another embodiment of the method for forming an anticorrosion film according to the present invention, the plating film is a zinc-nickel alloy plating film containing nickel in a range of more than 5% and less than 30%.

  In another embodiment of the method for forming an anticorrosion film according to the present invention, when the zinc or zinc alloy plating film is brought into contact with the solution, electrolysis is performed using the substrate as a cathode.

  The method for producing the anticorrosion film according to the present invention has excellent anticorrosion performance comparable to the film subjected to chemical conversion treatment using hexavalent chromium, and the excellent anticorrosion performance is obtained with good reproducibility and uniformity. An object of the present invention is to provide a method for producing an anticorrosion film in which variations in anticorrosion performance do not easily occur.

  Hereinafter, the chemical conversion treatment liquid of the present invention and the method of forming an anticorrosion plating film using the same will be described in detail including preferred embodiments.

In the present invention, zinc or a zinc alloy plating film is used as the plating film to be subjected to chemical conversion treatment. As the zinc alloy plating film, an alloy plating film such as zinc-nickel, zinc-iron, and zinc-tin is preferably used. Among them, a zinc-nickel alloy plating film having a high nickel content is particularly preferably used. As the zinc-nickel alloy plating film, one containing nickel in the range of 5 to 30 wt% is preferably used. A zinc-nickel alloy plating film containing 10 to 25 wt% nickel is more preferably used, and a zinc-nickel alloy plating film containing 17 to 22 wt% nickel is most preferably used.
In the case of a zinc-nickel alloy plating film, the anticorrosion performance increases with increasing nickel content up to approximately 20%, but when it exceeds 25%, the uniformity and reproducibility of the anticorrosion performance gradually decrease, and the product Variations in performance are recognized every time. This tendency becomes remarkable when it exceeds 30%. For this reason, it is preferable to limit to said composition range.
The thickness of the plating film is naturally determined arbitrarily in view of the required anticorrosion performance and cost, but usually a thickness of 1 μm or more, preferably about 5 to 20 μm is used.

Hereinafter, the chemical conversion treatment liquid will be described. The chemical conversion solution is usually provided in the form of an aqueous solution.
The first essential component of the solution is trivalent chromium ions. Examples of the supply source include chromium (III) chloride, chromium (III) sulfate, chromium (III) nitrate, chromium acetate (III), chromium phosphate (III), chromium oxalate (III), and chromium (III) alum. One type or two or more types selected from the group consisting of trivalent chromium obtained by reducing hexavalent chromium such as a trivalent chromium compound, chromate, and dichromate to trivalent with a reducing agent can be used. As will be described later, in the present invention, nitrate ion is also an essential component, so chromium (III) nitrate is more preferably used.
The concentration of trivalent chromium is preferably 0.01 to 20 g / L as chromium, and more preferably 0.1 to 10 g / L. If the concentration is low, a sufficient film thickness cannot be obtained, the corrosion resistance is inferior, and if it is too high, it is disadvantageous in terms of performance from the standpoint of performance and taking out of the processing liquid.

The second essential component of the chemical conversion treatment liquid of the present invention is nitrate ions. In addition to being supplied in the form of an acid or an alkali metal salt, nitrate ions may be supplied as a counter anion of trivalent chromium as described above, and are the fourth and fifth essential components as described later. It may be supplied in the form of a counter anion of a metal salt.
The concentration of nitrate, NO ₃ ^- 1~100g / L is preferably used as, 5 to 50 g / L is more preferably used, 5 to 30 g / L is preferably used.
Although it is related to the concentration of carboxylic acid ions such as oxalic acid described later, the pH of the solution for chemical conversion treatment of the present invention is preferably more than 2 and less than 6. More than 3 and less than 5 are more preferably used. Most preferably, more than 3.5 and less than 5 is used.

The third essential component of the chemical conversion treatment liquid of the present invention is an aliphatic poly (C) having 8 or less carbon atoms other than carbon constituting the carboxyl group, which is effective for uniformity of appearance and thickening of the film. Carboxylic acid. As the carboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, malic acid, tartaric acid, citric acid and the like are preferably used. Acid is most preferably used. In addition to being supplied in the form of acid, the carboxylate ion is used as a counter anion of a metal that is trivalent chromium, the fourth and fifth essential components described later, or a salt of an alkali metal or alkaline earth metal. It may be supplied.
The concentration of the carboxylic acid is preferably 0.1 to 50 g / L in total as the acid radical, more preferably 0.3 to 20 g / L, and most preferably 0.5 to 10 g / L. It is done. If the amount is larger than this, problems such as an economic loss and an increase in wastewater treatment burden occur, and if it is less, the effect of increasing the film thickness is difficult to obtain.

The fourth and fifth essential components of the chemical conversion treatment liquid of the present invention are effective to make the chemical conversion film uniform and thick (D) One or more kinds of metal ions selected from iron, cobalt and nickel And (E) zinc ions. Even if (D) or (E) is not used in combination, a certain degree of effect is shown, but by coexisting (D) and (E), they act synergistically and exert a strong effect.
In (D), nickel and iron are more preferably used, and nickel is most preferably used.
The source of these metal ions includes known inorganic salts such as nitrates, sulfates, chlorides and phosphates, various sulfonates such as methanesulfonate, and various organic acid salts such as acetates. Alternatively, a complex salt with a complexing agent such as EDTA is preferably used.
The total concentration of the metal ions is preferably 0.01 g / L or more and 100 g / L or less, more preferably 0.05 g / L or more and 50 g / L or less, and more preferably 0.1 g / L or more and 30 g / L or less. L or less is most preferably used.
If more than this, the metal will be excessively incorporated into the film, causing problems such as impairing the original performance of chromium, which is the main component of the film, and if it is less, the effect of making the film uniform or thicker will be obtained. It becomes difficult.

As the sixth essential component, (F) one or more aliphatic alcohols having 1 to 6 carbon atoms are added to the solution for chemical conversion treatment of the present invention. Specifically, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1--2-propanol, 2-methyl-2-propanol, 1-pentanol, 2- Pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, cyclohexanol and the like are preferably used, among which methanol, ethanol, 1 -Propanol, 2-propanol and 2-methyl-2-propanol are more preferably used, and methanol, ethanol and 2-propanol are most preferably used.
If the amount of alcohol is too small, stable corrosion resistance cannot be obtained. Conversely, if the amount of alcohol is too large, the liquid stability extremely decreases. Accordingly, the total concentration of the alcohol is preferably 0.1 g / L or more and 100 g / L or less, more preferably 1 g / L or more and 50 g / L or less, and 3 g / L or more and 20 g / L or less. Most preferably used.
The addition of alcohol, which is the sixth essential component, significantly improves the uniformity of the chemical conversion film formation. As a result, extremely excellent anticorrosion performance is achieved.

  (G) Colloidal silica can be further added to the chemical conversion treatment liquid of the present invention, which can be suitably used. Adding colloidal silica to the solution is effective in improving appearance and corrosion resistance. A colloidal silica having a particle size of 500 nm or less is preferably used, and a colloidal silica having a particle size of 50 nm or less is more preferably used. A suitable amount of colloidal silica added is 0.01 to 500 g / L, more preferably 1 to 150 g / L.

  In addition to general pigments and dyes, the chemical conversion treatment liquid of the present invention may contain coloring components such as animal light pigments, animal light dyes, fluorescent pigments, and fluorescent dyes. Generally, the range of 0.001 to 50 g / L is economical and effective. Such components can be added by dissolving in advance in alcohol. The alcohol used for this purpose should also be added to the concentration of (F) alcohol, which is the sixth essential component.

  In addition to the essential component nitric acid (ion), chloride ions, sulfate ions, phosphate ions, and the like may be included as inorganic acids for the purpose of appropriately etching the surface of Zn or a Zn alloy. For that purpose, it can be added in the form of hydrochloric acid, sulfuric acid, phosphoric acid or the like, or in the form of a salt thereof. The concentration of these ions can be added in the chemical conversion solution so as to be 1 to 100 g / L, preferably 5 to 30 g / L.

The preferable processing conditions for the chemical conversion coating production are a processing time of 5 to 300 seconds, a processing temperature of 10 to 80 ° C., and more preferably a processing time of 15 to 200 seconds and a processing temperature of 15 to 40 ° C. The most suitable processing conditions are a processing time of 30 to 150 seconds and a processing temperature of 20 to 30 ° C. The pH condition is as described above.
As a treatment method, the most popular dipping method as a chromate treatment method for a plated product is generally used in the present invention, but it can also be treated by a treatment method such as spray, roll coater, bar coater, spin coater or the like. is there.

As already described, the chemical conversion treatment applied in the present invention is usually carried out by bringing a zinc or zinc alloy plating film into contact with the solution of the composition of the present invention (most commonly, immersion). In this case, electrolysis can be used together for the purpose of thickening the chemical conversion film. The electrolytic conversion treatment is performed under the condition that the substrate to be treated, that is, the substrate on which the zinc or zinc alloy plating film is formed is used as a cathode, generally with a current density of 0.01 to 20 A / dm ² and a treatment time of 0.01 to 5 minutes. Are preferably used. More preferably, electrolysis of less than 1 A / dm ² or conditions of 2 minutes or less are used.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples, Arbitrary deformation | transformation can be made within the range of the technical idea of this invention.

Using a 7 x 10 cm steel plate as a test piece, after performing appropriate pretreatments such as degreasing, pickling, desmutting, activation, etc., after applying zinc-nickel alloy plating (Zn / Ni), then applying chemical conversion treatment A sample for evaluation was used. The thickness of the plating was 8-9 μm. The film thickness of the plating was measured by a fluorescent X-ray method using a Seiko Instruments model SFT9200. Ten samples were prepared under the same conditions, and a salt spray test was performed according to JIS Z 2371. Whether or not white rust was observed after 120 hours was used as a criterion for determination, and was classified as follows. A sample in which white rust was recognized in 3 or more of 10 samples was evaluated as rejected.
A: White rust does not occur in any of the 10 samples.
B: White rust occurred on one of 10 samples.
C: White rust occurred on 2 of 10 samples.
D: White rust occurred on 3 or more of 10 samples.

Comparative Example 1
Using a Yamato Kasei Zn-Ni alloy plating bath (Dynedin Alloy N-PL) (A1), plating was performed at a temperature of 25 ° C., a pH of 6.5, and a current density of ² A / dm ² . As a result of analysis by fluorescent X-ray (Seiko Instruments Model SFT9200), the nickel content in the film was 18 wt%.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B1).
Chemical conversion bath (B1) : chromium nitrate (III) (as chromium) 1 g / L, nickel nitrate (as nickel) 10 g / L, zinc nitrate (as zinc) 5 g / L, sodium oxalate (as oxalic acid) 2 g / L L, 35% by weight concentrated hydrochloric acid 20 g / L, sodium nitrate 7 g / L, pH 4.0.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 25 ° C., a treatment time of 60 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Comparative Example 2
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B2).
Chemical conversion bath (B2) : chromium (III) nitrate (as chromium) 1 g / L, zinc nitrate (as zinc) 5 g / L, sodium oxalate (as oxalic acid) 2 g / L, sodium nitrate 10 g / L, ethanol 10 g / L, pH 4.0.
The conditions of the chemical conversion treatment, that is, the contact method, treatment temperature, treatment time, drying temperature, and drying time were the same as those in Comparative Example 1.

Comparative Example 3
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B3).
Chemical conversion bath (B3) : chromium (III) nitrate (as chromium) 1 g / L, nickel nitrate (as nickel) 10 g / L, sodium oxalate (as oxalic acid) 2 g / L, 35% by weight concentrated hydrochloric acid 20 g / L Sodium nitrate 7 g / L, ethanol 10 g / L, pH 4.0.
The conditions of the chemical conversion treatment, that is, the contact method, treatment temperature, treatment time, drying temperature, and drying time were the same as those in Comparative Example 1.

Comparative Example 4
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B4).
Chemical conversion bath (B4) : chromium nitrate (III) (as chromium) 1 g / L, nickel nitrate (as nickel) 10 g / L, zinc nitrate (as zinc) 5 g / L, sodium nitrate 7 g / L, ethanol 10 g / L PH 4.0.
The conditions of the chemical conversion treatment, that is, the contact method, treatment temperature, treatment time, drying temperature, and drying time were the same as those in Comparative Example 1.

Comparative Example 5
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B5).
Chemical conversion bath (B5) : chromic anhydride (VI) 5 g / L, concentrated nitric acid 3 ml / L, concentrated sulfuric acid 2 ml / L.
The conditions for the chemical conversion treatment were immersion, treatment temperature at room temperature, treatment time 20 seconds, hot air drying, and drying time 5 minutes.

Example 1
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B6).
Chemical conversion bath (B6) : chromium (III) nitrate (as chromium) 1 g / L, nickel nitrate (as nickel) 10 g / L, zinc nitrate (as zinc) 5 g / L, sodium oxalate (as oxalic acid) 2 g / L L, sodium nitrate 7 g / L, ethanol 10 g / L, pH 4.0.
The conditions of the chemical conversion treatment, that is, the contact method, treatment temperature, treatment time, drying temperature, and drying time were the same as those in Comparative Example 1.

Example 2
The conditions were the same as in Example 1 except that the chemical conversion bath (B7) in which ethanol in Example 1 was replaced with methanol was used.

Example 3
The conditions were the same as in Example 1 except that the chemical conversion bath (B8) in which ethanol in Example 1 was replaced with i-propanol was used.

Example 4
The conditions were the same as in Example 1 except that the chemical conversion bath (B9) in which the ethanol in Example 1 was replaced with t-butanol was used.

Example 5
Plating was performed at a current density of 0.2 A / dm ² using the same plating bath (A1) as in the comparative examples and examples. As a result of analysis by fluorescent X-ray, the nickel content in the film was 7 wt%.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B10).
Chemical conversion bath (B10) : chromium (III) chloride (as chromium) 15 g / L, iron sulfate (as iron) 0.03 g / L, cobalt chloride (as cobalt) 0.03 g / L, zinc nitrate (as zinc) 0.05 g / L, potassium sodium tartrate 0.5 g / L, sodium oxalate (as oxalic acid) 30 g / L, 35% by weight concentrated hydrochloric acid 10 g / L, nitric acid 55 g / L, methanol 0.5 g / L, colloidal Silica 200 g / L, pH 2.5.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 12 ° C., a treatment time of 250 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 6
Plating was performed at a current density of 0.5 A / dm ² using the same plating bath (A1) as in the comparative examples and examples. As a result of analysis by fluorescent X-ray, the nickel content in the film was 12 wt%.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B11).
Chemical conversion bath (B11) : chromium (III) phosphate (as chromium) 1 g / L, iron chloride (as iron) 40 g / L, nickel chloride (as nickel) 0.1 g / L, zinc sulfate (as zinc) 7 g / L, sodium citrate 20 g / L, potassium oxalate (as oxalic acid) 0.4 g / L, 35 wt% hydrochloric acid 10 g / L, potassium nitrate 40 g / L, n-propanol 25 g / L, colloidal silica 10 g / L, pH 3.2.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 35 ° C., a treatment time of 20 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 7
Plating was performed at a current density of 4 A / dm ² using the same plating bath (A1) as in the comparative examples and examples. As a result of analysis by fluorescent X-ray, the nickel content in the film was 23 wt%.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B12).
Chemical conversion bath (B12) : chromium (III) oxalate (as chromium) 5 g / L, iron sulfate (as iron) 10 g / L, nickel nitrate (as nickel) 0.07 g / L, zinc chloride (as zinc) 5 g / L, malic acid 1 g / L, potassium oxalate (as oxalic acid) 15 g / L, 35 wt% hydrochloric acid 10 g / L, potassium nitrate 40 g / L, i-propanol 2 g / L, colloidal silica 100 g / L, pH 4.0 .
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 17 ° C., a treatment time of 170 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 8
Plating was performed at a current density of 8 A / dm ² using the same plating bath (A1) as in the comparative examples and examples. As a result of analysis by fluorescent X-ray, the nickel content in the film was 27 wt%.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B13).
Chemical conversion bath (B13) : chromium (III) chloride (as chromium) 0.05 g / L, cobalt nitrate (as cobalt) 10 g / L, zinc methanesulfonate (as zinc) 0.1 g / L, malonic acid 10 g / L L, potassium oxalate (as oxalic acid) 0.2 g / L, 35 wt% hydrochloric acid 10 g / L, 60 wt% concentrated nitric acid 3 g / L, n-butanol 70 g / L, colloidal silica 0.05 g / L, pH 2. 5.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 50 ° C., a treatment time of 10 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 9
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B14).
Chemical conversion bath (B14) : chromium (III) phosphate (as chromium) 3 g / L, nickel nitrate (as nickel) 10 g / L, zinc nitrate (as zinc) 5 g / L, potassium oxalate (as oxalic acid) 5 g / L, 35% by weight hydrochloric acid 20 g / L, potassium nitrate 55 g / L, i-propanol 10 g / L, colloidal silica 20 g / L, pH 4.0.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 25 ° C., a treatment time of 60 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 10
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B15).
Chemical conversion bath (B15) : chromium chloride (III) (as chromium) 7 g / L, nickel chloride (as nickel) 15 g / L, zinc chloride (as zinc) 4 g / L, potassium oxalate (as oxalic acid) 5 g / L L, 35% by weight hydrochloric acid 10 g / L, potassium nitrate 10 g / L, ethanol 10 g / L, colloidal silica 20 g / L, pH 4.0.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 25 ° C., a treatment time of 60 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 11
A plating sample was prepared under the same conditions using the same plating bath (A1) as in Comparative Example 1.
The plating sample was subjected to chromate treatment using the following chemical conversion treatment bath (B16).
Chemical treatment bath (B16): (as chromium) chromium nitrate (III) 1 g / L, cobalt nitrate (as cobalt) 5 g / L, nickel sulfate (as Ni) 3 g / L, (as zinc) of zinc sulfate 7 g / L, Potassium oxalate (as oxalic acid) 5 g / L, 35 wt% hydrochloric acid 10 g / L, sodium nitrate 10 g / L, ethanol 10 g / L, i-propanol 5 g / L, colloidal silica 20 g / L, pH 4.0.
The conditions for the chemical conversion treatment were immersion, a treatment temperature of 25 ° C., a treatment time of 60 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes.

Example 12
Using the same plating bath (A1) as in Example 1, a plating sample was prepared under the same conditions.
In the chemical conversion treatment, chromate treatment was performed using the same chemical conversion treatment bath (B2) as in Example 1.
The conditions of the chemical conversion treatment were the same as those in Comparative Example 1 with a treatment temperature of 25 ° C., a treatment time of 60 seconds, a drying temperature of 100 ° C., and a drying time of 10 minutes, but the sample was used as an electrolytic chromate method at 10 A / dm ² . .

  Table 1 shows the evaluation results of the samples after the salt spray test.

When the salt spray test of the sample pieces prepared under the conditions of Examples 1 and 12 was extended to 168 hours, white rust was generated on two of the 10 test pieces under the conditions of Example 1, while In the sample of the condition of Example 12, no white rust was observed on any of the 10 sheets.
The chemical conversion film of the sample pieces of Examples 1 and 12 was completely dissolved with dilute nitric acid, and the amount of chromium was quantified by plasma emission analysis using a model ICP-8100 manufactured by Shimadzu Corporation. As a result, the chromium content in the chemical conversion film of Example 1 was about 50 mg / m ² , whereas the chromium content in the chemical conversion film of Example 12 was about 75 mg / m ² . From this, it was clarified that the chemical conversion film was thickened by using the electrolytic chromate method, and more stable corrosion resistance was obtained.

Claims (10)

Substantially does not contain hexavalent chromium ions, and at least the following (A) to (F),
(A) trivalent chromium ion,
(B) nitrate ion,
(C) One or more aliphatic polycarboxylic acids having 8 or less carbon atoms other than carbon constituting the carboxyl group,
(D) One or more kinds of metal ions selected from iron, cobalt, and nickel,
(E) zinc ion,
(F) one or more aliphatic alcohols having 1 to 6 carbon atoms,
Chemical conversion solution for zinc or zinc alloy plating film containing 0.01 to 20 g / L (A),
(B) 1-100 g / L,
0.1 to 50 g / L in total with (C) as the acid radical,
(D) and (E) in total 0.01 to 100 g / L
0.1 to 100 g / L in total for (F)
The chemical conversion liquid of Claim 1 contained.   The chemical conversion treatment liquid according to claim 1 or 2, wherein the (F) alcohol is selected from methanol, ethanol, propanol, and butanol.   The chemical conversion solution according to any one of claims 1 to 3, wherein the concentration of the (F) alcohol is 3 g / L or more.   (G) The chemical conversion liquid as described in any one of Claims 1-4 which further contains colloidal silica.   The said (C) aliphatic polycarboxylic acid is oxalic acid, The chemical conversion liquid as described in any one of Claims 1-5.   A method for forming an anticorrosion film, comprising bringing a zinc or zinc alloy plating film applied on a substrate into contact with the chemical conversion treatment solution according to any one of claims 1 to 6.   The method for forming an anticorrosion film according to claim 7, wherein the plating film is a zinc-nickel alloy plating film.   The method of forming an anticorrosion film according to claim 7 or 8, wherein the plating film is a zinc-nickel alloy plating film containing nickel in a range of 5 to 30 wt%.   The method for forming an anticorrosion film according to any one of claims 7 to 9, which involves electrolyzing the base body as a cathode when the zinc or zinc alloy plating film is brought into contact with the solution.