JP3088623B2 - Method for forming zinc phosphate film on metal surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a zinc phosphate film on a metal surface by bringing the metal surface into contact with an acidic zinc phosphate film treating solution. Has high rust prevention effect with a small amount of film,
The present invention also relates to a method for forming a zinc phosphate film with a small amount of zinc phosphate sludge by-produced during the treatment.

[0002]

2. Description of the Related Art As a method for preventing a metal surface from being corroded by atmospheric oxygen, sulfur oxides, rainwater, seawater, etc., a method of forming a zinc phosphate film on a metal surface is known. The zinc phosphate film must have excellent adhesion to the metal surface that is the base, and must also have excellent adhesion to the coating film formed on it. It is necessary to show a rust prevention effect. Such a zinc phosphate film is formed on metal materials in various fields such as an automobile body, other automobile parts, building materials, and furniture.

For example, in an automobile body or the like, a material in which zinc or alloyed zinc plating is applied to the surface of a steel material is used in order to further improve the corrosion resistance after painting, and to reduce the weight of the automobile body. An aluminum alloy plate is used. Materials in which the surface of a steel sheet is subjected to zinc or alloyed zinc plating, or a material in which an aluminum material is combined with iron and / or galvanized material are used in various fields such as automobiles and building materials. It is desired to treat the metal surface with the same zinc phosphate coating solution to form a corrosion-resistant coating having excellent adhesion.

[0004] By simultaneously applying a zinc phosphate coating to a metal surface having an iron-based surface, a zinc-based surface, and an aluminum-based surface, a zinc phosphate film suitable for cationic electrodeposition coating is formed on the metal surface. Various methods have been proposed.

In the method for forming a zinc phosphate film described in Japanese Patent Publication No. 3-191071, zinc ions of 0.1 to
2.0 g / liter, nickel ion 0.1-4 g / liter, manganese ion 0.1-3 g / liter, phosphate ion 5-40 g / liter, nitrate ion 0.1-1
5 g / l, simple fluoride (HF conversion) 0.2-
0.5 g / liter, complex fluoride 0.01 ≦ [complex fluoride] / [simple fluoride] ≦ 0.5 (molar ratio), and an acidic zinc phosphate treatment liquid containing a film formation accelerator as a main component Used.

[0006] In the method for forming a zinc phosphate film described in Japanese Patent Application Laid-Open No. 4-228579, zinc ions of 0.3 to 0.3
1.7 g / liter, manganese ion 0.2-4 g / liter, copper ion 0.001-0.03 g / liter,
Phosphate ions 5 to 30 g / l, simple fluoride 0.
An acidic zinc phosphate treatment liquid containing 1 to 1 g / liter (in terms of F) and a film formation accelerator as a main component and not containing nickel ions is used.

[0007]

However, the conventional method of forming a zinc phosphate film has a problem in that a large amount of sludge is produced as a by-product when the zinc phosphate film is formed. For example, when treating an iron-based metal surface, mixed sludge with zinc phosphate containing iron phosphate as a main component is generated, and when treating a zinc-based metal surface, zinc phosphate is used as a main component. Sludge is produced as a by-product. In the case of treating an aluminum-based metal surface, Na ₃ AlF ₆ (cryolite),
Sludge containing K ₂ NaAlF ₆ (elpasolite) as a main component is by-produced. These sludges disperse in the liquid of the zinc phosphate treatment tank or settle and deposit in the tank,
The treatment efficiency of the zinc phosphate treatment is reduced, or the coating performance of the object to be treated is deteriorated. Therefore, it is necessary to remove by-product sludge out of the system using a filter or the like. Furthermore, sludge removed outside the system needs to be treated as industrial waste, which further raises the problem that disposal costs are high.

When treating an iron-based material, the amount of sludge generated is proportional to the amount of iron eluted from the metal material to be treated during the treatment. Therefore, in order to suppress the amount of sludge generation, it is only necessary to select processing conditions that reduce the amount of iron elution, but if such conditions are selected, the coating weight of the zinc phosphate coating decreases, and sufficient coating corrosion resistance is obtained. The problem arises that it cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem, to reduce the amount of sludge generated as a by-product during the formation of a zinc phosphate film, and to exhibit a high rust-preventive effect with a smaller film amount than before. An object of the present invention is to provide a method for forming a zinc phosphate film.

[0010]

The method for forming a zinc phosphate film according to the present invention is a method in which a metal surface is brought into contact with an acidic zinc phosphate film treating solution to form a zinc phosphate film on the surface. Zinc phosphate coating solution is the main component
0.1 to 2 g / liter of zinc ion, 0.1 to 4 g / liter of nickel ion and / or cobalt ion, 0.1 to 3 g / liter of manganese ion, 0.0 of copper ion
0.05 to 0.2 g / liter, trivalent iron ion 0.01 to
The treatment liquid contains 0.5 g / liter, phosphate ion 5 to 40 g / liter, nitrate ion 0.1 to 15 g / liter, fluorine compound 0.05 to 3 g / liter (in terms of F), and a film formation accelerator. Is managed within the range of the management standard.

The metal surface on which the zinc phosphate film is to be formed in the present invention is not particularly limited. For example, a metal surface selected from an iron-based surface, a zinc-based surface and an aluminum-based surface alone, or 2 of these surfaces
The metal surface of the material to be treated having a combination of more than one kind is exemplified.

In the present invention, the concentration of zinc ion is 0.1.
It is preferably from 1 to 2.0 g / liter, more preferably from 0.3 to 1.5 g / liter. If the zinc ion concentration is too low, a uniform zinc phosphate film will not be formed on the metal surface, and there will be a lot of scars, and a partially blue-colored film may be formed. If the zinc ion concentration is too high, a uniform zinc phosphate film is generated,
It is easy to become a film which is easily dissolved in alkali, and in particular, the film may be easily dissolved by being exposed to an alkali atmosphere during cationic electrodeposition. As a result, in general, the desired salt-water resistance is lowered, and particularly in the case of an iron-based surface, the desired performance cannot be obtained, such as deterioration of the scab resistance (prevention of rust (scab erosion) in the form of casabuta). It is unsuitable as a base for electrodeposition coating, especially for cationic electrodeposition coating.

In the present invention, the concentration of nickel ions and / or cobalt ions is preferably 0.1 to 4 g / liter, more preferably 0.5 to 1.5 g / l.
g / liter. If the concentration of nickel ions and / or cobalt ions is too low, the film will be easily dissolved in alkali, and in particular, the film may be easily dissolved by exposure to an alkali atmosphere during cation electrodeposition. If the concentration of nickel ions and / or cobalt ions is too high, the effect corresponding to the increase in concentration cannot be expected, which is economically disadvantageous.

In the present invention, the manganese ion concentration is
The range is preferably from 0.1 to 3 g / liter, and more preferably from 0.6 to 3 g / liter. If the manganese ion concentration is too low, the effect of improving the adhesion between the zinc-based surface and the coating film and the resistance to hot salt water in cationic electrodeposition coating tends to be insufficient. On the other hand, if the manganese ion concentration is too high, an effect corresponding to the increase in the amount cannot be expected, which is economically disadvantageous.

In the present invention, the concentration of copper ions is 0.1
The range is preferably from 005 to 0.2 g / liter, more preferably from 0.01 to 0.1 g / liter. If the concentration of copper ions is too low, the corrosion resistance may be deteriorated, particularly on the iron-based surface, and the desired performance may not be obtained. If the concentration of copper ions is too high, the corrosion resistance of the zinc-based surface or aluminum-based surface is rather deteriorated, and desired performance may not be obtained.

In the present invention, the concentration of trivalent iron ions is preferably in the range of 0.01 to 0.5 g / l, more preferably in the range of 0.02 to 0.1 g / l. If the concentration of trivalent iron ions is too low, the effect of miniaturizing the zinc phosphate film crystals may be insufficient, and the desired rust prevention performance may not be obtained with a low film amount. If the concentration of trivalent iron ions is too high, a non-uniform blue-colored film tends to be formed on the iron-based surface.

In the present invention, the concentration of phosphate ions is
It is preferably 5 to 40 g / liter, and more preferably 10 to 30 g / liter. If the phosphate ion concentration is too low, a non-uniform film is likely to be formed, and if the phosphate ion concentration is too high, the effect corresponding to the increase in the concentration cannot be expected, and the amount of chemical used increases. Financially disadvantageous.

In the present invention, the nitrate ion concentration is set at 0.1.
The range is preferably from 1 to 15 g / liter, more preferably from 2 to 10 g / liter. If the concentration of nitrate ions is too low, it becomes difficult to maintain the concentration of trivalent iron ions in the treatment solution within the range specified in the present invention, exhibiting a high rust prevention effect with a small coating amount, and In some cases, the effect of the present invention that the amount of generated sludge is small cannot be sufficiently obtained. If the nitrate ion concentration is too high, the effect corresponding to the increase in the concentration cannot be expected, and this is economically disadvantageous.

In the present invention, the fluorine compound as F is preferably in the range of 0.05 to 3 g / liter. The fluorine compound used in the present invention is at least one selected from water-soluble simple fluorides and complex fluorides. The concentration of the fluorine compound is the total value of the simple fluoride and the complex fluoride, and is equal to 0.1 in F as described above.
It is preferably in the range of 0.5 to 3 g / liter, and more preferably in the range of 0.1 to 2 g / liter.
If the concentration of the fluorine compound is too low, the effect of miniaturizing the zinc phosphate film becomes insufficient, and the desired rust prevention performance may not be obtained with a small amount of the film. On the other hand, if the concentration of the fluorine compound is too high, the effect corresponding to the increase in the concentration cannot be expected, which is economically disadvantageous.

When the metal surface is an aluminum-based metal surface, the fluorine compound contained in the zinc phosphate coating solution reacts with the aluminum surface and is consumed as the treatment proceeds. Therefore, it is necessary to replenish the fluoride in order to maintain the concentration within a predetermined range as the processing proceeds. When complex hydrofluoric acid such as hydrosilicofluoric acid and borofluoric acid is contained as the fluorine compound, the consumed complex is used to maintain the activity of the zinc phosphate coating solution within a predetermined range. The need to measure hydrofluoric acid arises. For example, in the case of hydrosilicofluoric acid, it is consumed by a reaction represented by the following formula. 2Al + 3H ₂ SiF ₆ → Al ₂ (SiF ₆ ) ₃ + 3H ₂ (I)

The activity of the acidic zinc phosphate coating solution containing such complex hydrofluoric acid can be determined by the activity measuring method disclosed in Japanese Patent Application Laid-Open No. 6-240466 filed by the present applicant. And it can be measured and managed by the activity management method. In the present invention, the activity is controlled by using such a method, and a zinc phosphate film can be formed by using an acidic zinc phosphate film treating solution having an activity within a predetermined range at all times. The activity measurement method and the management method will be described later in detail.

The acidic zinc phosphate coating solution used in the present invention contains a coating conversion accelerator. Examples of such a film formation accelerator include nitrite ion, m
-Nitrobenzenesulfonic acid ion, hydrogen peroxide, hydroxylamine and the like.

The concentration of the nitrite ion is 0.01 to
It is preferably 0.5 g / liter, more preferably 0.1 g / l.
01 to 0.4 g / liter. The concentration of the m-nitrobenzenesulfonic acid ion is preferably from 0.05 to 5 g / liter, more preferably from 0.1 to 4 g / liter. The concentration of hydrogen peroxide (in terms of H ₂ O ₂ 100%) is preferably 0.5 to 10 g / liter.
Further, the concentration of hydroxylamine is 0.5-2.
5 g / liter is preferred, and more preferably 1.0 to
2.0 g / l. When the concentration of these film formation accelerators is less than the above range, sufficient chemical conversion treatment cannot be performed on the iron-based surface, and yellow rust is easily generated. It is easy to form a non-uniform film.

In the present invention, the zinc phosphate coating solution may contain an organic acid to make the zinc phosphate coating crystals finer. Such organic acids include, for example, citric acid and tartaric acid,
Particularly, citric acid which exhibits a synergistic effect in the presence of trivalent iron ions in the treatment liquid is preferable. The concentration of such an organic acid is preferably from 0.1 to 2 g / liter, more preferably from 0.2 to 1 g / liter. If the content of the organic acid is too small, the effect of refining the zinc phosphate film crystals is small, and if the content of the organic acid is too large, it is easy to form a blue-colored nonuniform film on the iron-based surface. .

When a zinc phosphate film is formed on an iron-based metal surface by the method for forming a zinc phosphate film of the present invention, the amount of the film is preferably 0.5 to 2.0 g / m ² ,
More preferably, it is 0.7 to 1.5 g / m ² . If the coating amount is too small, the coating corrosion resistance tends to be insufficient.

The average particle size of the crystals of the zinc phosphate film formed on the surface of the iron-based metal is preferably 1-2 μm. If the average particle size is less than 1 μm, the crystals become too fine and the film tends to be a blue-colored non-uniform film. When the average particle size exceeds 2 μm, the amount of the coating exceeds 2.0 g / m ^2, and the effect of the present invention for reducing the amount of sludge generated tends to be insufficient.

When a zinc phosphate film is formed on a zinc-based metal surface by the method for forming a zinc phosphate film of the present invention, the amount of the zinc phosphate film is preferably 1.0 to 4.0 g / m ^2. And more preferably 1.5 to 2.5 g / m ² . When the coating amount is too small, the coating corrosion resistance tends to be insufficient, and when the coating amount is too large, the coating adhesion tends to be insufficient.

According to the method for forming a zinc phosphate film of the present invention,
Forming a zinc phosphate coating on aluminum-based metal surfaces
The amount of zinc phosphate coating is 0.5-3.0 g
/ M ^TwoIs more preferable, and more preferably 1.0 to 2.0 g
/ M^TwoIt is. If the coating amount is too small, the coating corrosion resistance will be poor.
If the coating amount is too large, the coating adhesion will be insufficient.
Tend to be.

The temperature of the processing solution in the method for forming a zinc phosphate film of the present invention is preferably from 20 to 70 ° C, more preferably from 35 to 60 ° C. If the temperature of the treatment liquid is too low, the film formation properties are poor and long-term treatment is required, and if the treatment liquid temperature is too high, the balance of the treatment liquid is lost due to decomposition of the film formation accelerator and generation of precipitation. Easy to obtain good film.

The treatment time in the method for forming a zinc phosphate film of the present invention is preferably 15 seconds or more, and more preferably 30 to 120 seconds. If the treatment time is too short, a film having desired crystals may not be formed sufficiently.
When treating a metal surface having a complicated shape such as an automobile body, it is preferable to perform a combination of the immersion treatment and the spray treatment. In this case, for example, first
The immersion treatment is performed for 5 seconds or more, preferably 30 to 120 seconds, and then the spray treatment is performed for 2 seconds or more, preferably 5 to 45 seconds. Further, in order to wash off sludge adhering during the immersion treatment, it is preferable that the spray treatment is as long as possible. As described above, the method for forming a zinc phosphate film of the present invention can be performed in the form of immersion treatment, spray treatment, or a combination thereof.

In the method for forming a zinc phosphate film according to the present invention, the components contained in the zinc phosphate coating solution are consumed together with the chemical conversion treatment. Replenish by adding components to the processing solution as needed.
It is necessary to continuously maintain the composition of the processing solution. Since not all components contained in the processing liquid are consumed at the same ratio, it is preferable to prepare two or three types of concentrated processing liquid for replenishment. Regarding trivalent iron ions in the zinc phosphate treatment solution, treatment of iron (ii) ion eluted by addition of ferric nitrate or ferric citrate or reaction with the zinc phosphate treatment solution on the steel surface It can also be supplied by oxidation in liquid.

In the method for forming a zinc phosphate film of the present invention, when a complex hydrofluoric acid selected from hydrosilicofluoric acid and borofluoric acid is contained as a fluorine compound in the zinc phosphate coating solution, Collecting a liquid to be measured from the acidic zinc phosphate coating solution, adding a predetermined amount of simple fluoride to the collected liquid to be measured, and adjusting the HF concentration in the liquid to be measured to which the simple fluoride is added. A step of evaluating the activity of the solution to be measured by measuring, and a treatment with zinc phosphate such that the activity of the acidic zinc phosphate coating solution is within the range of the management standards based on the evaluation of the activity of the solution to be measured. By adjusting the activity by adding simple fluoride to the liquid,
The activity in the acidic zinc phosphate coating solution can be controlled within the range of the control standard.

The complex hydrofluoric acid reacts with the aluminum,
Consumed by producing aluminum salts. For example, when the complex hydrofluoric acid is H ₂ SiF ₆ , Al ₂ (SiF ₆ ) ₃ is formed by the reaction with aluminum. By adding a simple fluoride, for example, HF, the following formula is obtained. Such a reaction occurs. Al ₂ (SiF ₆ ) ₃ + 12HF → 2H ₃ AlF ₆ + 3H ₂ SiF ₆ (II)

As described above, the reaction between the aluminum salt of complex hydrofluoric acid and the simple fluoride proceeds, and the simple fluoride is consumed until the aluminum salt of complex hydrofluoric acid disappears. Therefore, the amount of the aluminum salt of the complex hydrofluoric acid was measured by adding an excess of the simple fluoride and measuring the simple fluoride remaining after the reaction with the aluminum salt of the complex hydrofluoric acid as the HF concentration. , Activity can be evaluated. The remaining simple fluoride can be easily measured by a silicon electrode meter or the like. It is preferable that the measurement of the HF concentration by the silicon electrode meter is performed by selecting a concentration range having a small measurement error. When the Surf Proguard 101N (manufactured by Nippon Paint Co., Ltd.) is used as the silicon electrode meter, the residual simple hydrofluoric acid is measured. It is preferable to add a predetermined amount of simple fluoride to the liquid to be measured so that the compound concentration becomes 200 to 500 ppm in terms of HF.

The simple fluoride which reacts with the aluminum salt of complex hydrofluoric acid in the liquid to be measured is equivalent to 6 times the aluminum salt in terms of HF. Empirically, the concentration of the aluminum salt present in the treated solution after the treatment is roughly estimated from the treatment conditions and the like, and the corresponding simple fluoride concentration can be obtained. Therefore, by adding a simple fluoride concentration within a range that can be measured by a silicon electrode meter to this concentration, a predetermined amount of the simple fluoride to be added to the liquid to be measured can be determined.

According to the above activity control method, the liquid to be measured is collected from the processing solution in the zinc phosphate coating solution bath, and the activity in the liquid to be measured is determined by the simple fluoride as described above. Is measured to evaluate the activity, and based on the evaluation of the activity, a simple fluoride is added to the treatment solution in the zinc phosphate treatment solution tank. The aluminum salt of complex hydrofluoric acid in the zinc phosphate treatment solution is converted to complex hydrofluoric acid by the addition of simple fluoride, and the activity of the zinc phosphate coating solution must be within the control standards. Can be.

The simple fluoride to be added in the above activity control method includes HF, NaF, NaHF ₂ , K
F, KHF ₂ , NH ₄ F, NH ₄ HF _{2 and the} like are used.

[0038]

According to the method for forming a zinc phosphate film of the present invention, the amount of generated zinc phosphate sludge during chemical conversion treatment can be reduced, and a higher rust-preventive effect can be obtained with a smaller amount of film than before. Can be formed.

Further, according to the present invention, a zinc phosphate film is formed on a metal material selected from an iron-based surface, a zinc-based surface and an aluminum-based surface alone or a metal material obtained by combining two or more of these surfaces. It is possible to form a zinc phosphate film which is excellent in coating film adhesion and corrosion resistance and is suitable for electrodeposition coating, in particular, cationic electrodeposition coating.

[0040]

EXAMPLES Hereinafter, the present invention will be described with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

Examples 1-4 and Comparative Examples 1-7 (1) Metals to be treated Cold-rolled steel sheet (SPC) and galvannealed steel sheet (G
A) was used. (2) Processing Step The metal material to be processed was continuously processed according to the following steps to obtain a coated metal plate. (A) Degreasing → (b) Rinsing → (c) Surface adjustment → (d) Chemical conversion (dip treatment) → (e) Rinsing → (f) Pure water → (g)
Drying → (h) painting (3) Processing conditions

The above steps will be described below. (A) Degreasing Alkaline degreasing agent (trade name “Surf Cleaner SD250” manufactured by Nippon Paint Co., Ltd.) was used at a concentration of 2% by weight,
The immersion treatment was performed at 0 ° C for 2 minutes. The bath management at this time was performed with alkalinity (10 parts by using bromophenol blue as an indicator).
(ml number of 0.1N HCl required for neutralization of the ml bath) was maintained at the initial value. As a replenishing agent, Surf Cleaner SD250 was used.

(B) Rinse with water Tap water was used to carry out spray cleaning with water pressure. (C) Surface Conditioning A surface conditioner (trade name “Surf Fine 5N-5” manufactured by Nippon Paint Co., Ltd.) was used at a concentration of 0.1% by weight and immersed at room temperature for 15 seconds. Bath management is Surf Fine 5N
This was done by replenishing -5 and maintaining alkalinity.

(D) Chemical conversion (dip treatment) Using a zinc phosphate treatment solution having the composition shown in Table 1, immersion treatment was performed at 40 ° C. for 2 minutes. The bath management was performed by using the NO ₂ ion concentration and free acidity of the treatment solution (0.1 N-NaOH required for neutralizing a 10 ml bath using bromophenol blue as an indicator).
Ml number. However, when the treatment bath contains cobalt, 0.1 N-NaOH required to reach pH 3.6 is used.
Ml number. ) Is measured, and a replenishing thickening agent composed of a 20% by weight aqueous solution of sodium nitrite is replenished in response to a decrease in NO ₂ ion concentration, and replenishment is performed to supply other components according to a decrease in free acidity. The treatment was carried out by replenishing the treating solution with a thickening agent for use and maintaining the free acidity and the NO ₂ ion concentration at the initial values.

[0045]

[Table 1]

(E) Washing Using tap water, washing was carried out at room temperature for 15 seconds. (F) Pure water washing Ion-exchanged water was used for immersion at room temperature for 15 seconds. (G) Drying It was dried at 100 ° C. for 10 minutes.

(H) Coating Using a cationic type electrodeposition paint (trade name "Power Top U-1000") manufactured by Nippon Paint Co., a cationic electrodeposition coating is carried out according to a conventional method to form an electrodeposited coating film having a thickness of 30 μm. Then, a melamine alkyd intermediate coating from Nippon Paint Co., Ltd. was applied thereon in a conventional manner to form an intermediate coating film having a thickness of 30 μm, and a melamine alkyd top coating from Nippon Paint Co., Ltd. was formed thereon by a conventional method. To form a 40 μm-thick overcoat film.

The following tests were carried out on the zinc phosphate-treated plates obtained in Examples 1 to 4 and Comparative Examples 1 to 7 and the coated metal plates coated with the same, and the zinc phosphate coating treatment characteristics and coating quality were obtained. Was evaluated. Table 2 shows the obtained results.

(Characteristics of zinc phosphate film treatment) The following film amount and iron elution amount were measured by peeling the zinc phosphate film. The coating was peeled off by immersing the cold-rolled steel sheet in a 5% chromic anhydride solution at 75 ° C. for 15 minutes. The galvannealed steel sheet was immersed in a 5% chromic anhydride solution at 20 ° C. for 1 minute.

[0050] The coating amount of zinc phosphate treated sheet was weighed again weighed after decapsulation above conditions, the coating weight in weight loss of m ² in terms (g /
m ² ) is calculated.

Iron Elution Amount A cold-rolled steel sheet previously degreased with a solvent is weighed, zinc phosphate treatment is performed under the above conditions, and the zinc phosphate-treated plate is peeled off under the above conditions and weighed again. calculating the iron eluted amount (g / m ²⁾ in a weight loss of m ² basis.

(Coating Quality) Water Resistance Secondary Adhesion Test A three-coat coated plate which had been subjected to electrodeposition and intermediate topcoating was subjected to 50 coating tests.
Immersed in deionized water at 200C for 20 days. After that, the cut portion reaches the metal plate of the base, and a goban pattern (100 pieces) at 1 mm intervals is formed with a sharp cutter, and an adhesive tape is stuck on each side thereof, and then this is peeled off. Then, the number of paint films remaining on the painted plate was counted.

Scab Resistance Test A cut reaching the base metal plate was made with a sharp cutter on a three-coat coated plate which had been subjected to electrodeposition and middle top coating, and then the coated plate was subjected to a 5% salt spray test (JIS-JIS). Z-237
One cycle: 1, 2 minutes) → drying (60 ° C, 58 minutes) → wet test (95% RH, 50 ° C, 3 hours) 2
It was subjected to a 00 cycle corrosion test. The maximum width (one width from the cut portion: mm) of the coating film abnormality (such as thread rust or blister) on the coated surface after the test was examined.

[0054]

[Table 2]

In Examples 1 to 4, the coating quality was good and the amount of iron released due to the zinc phosphate coating treatment on the cold rolled steel sheet was small, so that the amount of sludge generated was also small. Comparative Example 1
Since it does not contain copper ions and trivalent iron ions, there is no problem in coating quality, but the amount of iron eluted during the treatment of the cold-rolled steel sheet with zinc phosphate is large, and the amount of sludge generated is large.

In Comparative Example 2, since no copper ion was contained,
The coating corrosion resistance of the cold rolled steel sheet was not sufficiently improved, and the amount of iron eluted during the treatment of the zinc phosphate film on the cold rolled steel sheet was large, and the amount of sludge generated was large.

In Comparative Example 3, since no trivalent iron ions were contained, the zinc phosphate film crystals formed on the cold-rolled steel sheet were not sufficiently densified, and iron was eluted when the zinc phosphate film was formed. The amount was large and the amount of sludge generated was large.

In Comparative Example 4, since no manganese ion was contained, the coating adhesion of the galvannealed steel sheet was poor. Comparative Example 5 did not contain nickel ions and cobalt ions, and thus the coating adhesion of the galvannealed steel sheet was insufficient.

In Comparative Example 6, the coating quality of the cold-rolled steel sheet and the galvannealed steel sheet was poor because it did not contain nickel ions, cobalt ions, copper ions, and trivalent iron ions.

In Comparative Example 7, since no fluorine compound was contained, the zinc phosphate film crystals formed on the cold-rolled steel sheet were not sufficiently densified, and a large amount of sludge was generated because of a large amount of iron eluted.

Example 5 As processing targets, a cold-rolled steel sheet and an aluminum alloy sheet (A
1 / Mg alloy system) (processing area ratio cold-rolled steel sheet: aluminum alloy sheet = 7: 3) was used. Using a zinc phosphate coating solution having the composition shown in Table 3, a replenishment thickening agent consisting of a 20% by weight aqueous solution of sodium nitrite was replenished in accordance with a decrease in the NO ₂ ion concentration of the zinc phosphate coating solution, A replenishing concentrated treating agent for supplying other components (excluding simple fluoride) in accordance with the decrease in the free acidity is replenished to the treatment liquid, and other conditions are the same as those in the above-described embodiment. Was performed and coating was performed to obtain a coated metal plate.

The activity of the processing solution is controlled by continuously measuring the activity using a silicon electrode meter (trade name “Surf Proguard 101N”) according to the above-described activity management method, and measuring the activity. In order to maintain the initial value, a concentrated replenishing agent consisting of a 2% by weight aqueous solution of sodium acid fluoride was added to the treatment liquid. 1 m ² per liter of processing liquid
Table 4 shows the evaluation results of the coating properties and coating quality after the treatment.

Comparative Example 8 In the same manner as in Example 5 above, a zinc phosphate treatment solution shown in Table 3 was used, and the activity of the treatment solution was not controlled and a 2% by weight aqueous solution of sodium acid fluoride was not added. A zinc phosphate treatment was performed in the same manner as in Example 5 described above, followed by painting to obtain a painted metal plate. The activity in the zinc phosphate treatment liquid after 1 m ² treatment per liter of treatment liquid was completely lost, and free hydrofluoric acid was not present. Table 4 shows the evaluation results of the coating properties and coating quality.

[0064]

[Table 3]

[0065]

[Table 4]

As shown in Table 4, in Example 5 treated according to the present invention, a good zinc phosphate film was formed not only on a cold-rolled steel sheet but also on an aluminum alloy material.
Good coating quality was shown.

On the other hand, without supplying simple fluoride,
In Comparative Example 8 in which the concentration of free hydrosilicofluoric acid was lower than the specified range of the fluorine compound of the present invention, no good zinc phosphate film was formed on the aluminum alloy material. Also, in the cold-rolled steel sheet, the crystal grain size of the zinc phosphate coating was increased, and the amount of iron eluted was increased, generating a large amount of sludge.

Continuation of the front page (56) References JP-A-5-287549 (JP, A) JP-A-5-195245 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 22 / 00-22/86

Claims (8)

(57) [Claims] 1. A method for forming a zinc phosphate film on a metal surface by bringing a metal surface into contact with an acidic zinc phosphate film treatment solution, wherein the acid zinc phosphate film treatment solution comprises: 0.1 to 2 g / liter of zinc ion, nickel ion and / or
Or 0.1 to 4 g / liter of cobalt ion, 0.1 to 3 g / liter of manganese ion, 0.005 of copper ion
0.2 g / liter, trivalent iron ion 0.01 to 0.1 g / l
5 g / liter, phosphate ion 5-40 g / liter,
A method for forming a zinc phosphate film on a metal surface, comprising 0.1 to 15 g / liter of nitrate ions, 0.05 to 3 g / liter of a fluorine compound (in terms of F), and a film formation accelerator. 2. The method according to claim 1, wherein the film formation accelerator comprises 0.01 to 0.5 g / l of nitrite ion, 0.05 to 5 g / l of m-nitrobenzenesulfonic acid ion, 0.5 to 10 g / l of hydrogen peroxide and Hydroxylamine
The method for forming a zinc phosphate film on a metal surface according to claim 1, wherein the method is at least one selected from 5 to 2.5 g / liter. 3. The metal surface is a metal surface of a material to be treated having a single metal surface selected from an iron-based surface, a zinc-based surface, and an aluminum-based surface, or a combination of two or more of these surfaces. The method for forming a zinc phosphate film on a metal surface according to claim 1 or 2. 4. The activity of the acidic zinc phosphate coating solution containing complex hydrofluoric acid selected from hydrosilicic acid and borofluoric acid as the fluorine compound. A step of collecting a liquid to be measured from the acidic zinc phosphate coating solution; a step of adding a predetermined amount of simple fluoride to the collected liquid to be measured; Estimating the activity of the solution to be measured by measuring the HF concentration of the solution; and, based on the evaluation of the activity of the solution to be measured, the activity of the acidic zinc phosphate coating solution is within the range of the management standard. Adjusting the activity by adding a simple fluoride to the acidic zinc phosphate coating solution so that the acidic zinc phosphate coating solution is controlled to be within the range of the control standard. Zinc phosphate coating on metal surface Forming method. 5. A zinc phosphate film formed on a metal surface by the method for forming a zinc phosphate film on a metal surface according to claim 1, wherein the metal surface is an iron-based metal surface. A zinc phosphate coating, wherein the coating amount of the zinc phosphate coating on the iron-based metal surface is 0.5 to 2.0 g / m ² . 6. An average particle size of the crystals of the zinc phosphate film is 1 to 6.
The zinc phosphate coating according to claim 5, which has a thickness of 2 µm. 7. A zinc phosphate film formed on a metal surface by the method for forming a zinc phosphate film on a metal surface according to claim 1, wherein the metal surface is a zinc-based metal surface. A zinc phosphate coating, wherein the coating amount of the zinc phosphate coating on the zinc-based metal surface is 1.0 to 4.0 g / m ² . 8. A zinc phosphate film formed on a metal surface by the method for forming a zinc phosphate film on a metal surface according to claim 1, wherein the metal surface is an aluminum-based metal surface. A zinc phosphate coating, wherein the coating amount of the zinc phosphate coating on the aluminum-based metal surface is 0.5 to 3.0 g / m ² .