JPH11152588A - Composition for forming rust preventive protective coating for metal and its formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form coating combining a uniform and satisfactory appearance and corrosion resistance without using harmful hexavalent chromium at the time of forming rust preventive protective coating on the surface of zinc, a zinc alloy or the like and to obtain rust preventive protective coating particularly on an iron product applied with galvanizing other than steel sheets for which application type coating is industrially difficult in fact. SOLUTION: The composition for forming rust preventive coating for metals is the one (1) contg. 0.01 to 100 g/L trivalent chromium ions, 0.1 to 200 g/L phosphate ions and 0.01 to 100 g/L nitrate ions, or (2) contg. 0.01 to 100 g/L trivalent chromium ions and one kind selected from the groups consisting of chlorine, fluorine, sulfate ions, nitrate ions and acetate ions by 0.1 to 200 g/L. (3) A composition for forming rust preventive coating for metals further contg. a silicon compd. or phosphoric acid to the composition of (1) or (2) is formed as coating on the surface of zinc, aluminum, magnesium, iron, nickel, cadmium, silver, copper or alloys thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to zinc, aluminum, magnesium, iron, nickel, cadmium, silver, copper and alloys thereof and metal materials plated with these materials. The present invention relates to a rust-preventive protective coating of an iron part provided.

[0002]

2. Description of the Related Art There are various kinds of films as rust-preventive protective films on the surface of zinc and zinc alloys. However, no film corresponding to the present invention has been found in the prior knowledge, and the present invention provides a film with new knowledge. is there. Generally, zinc or zinc alloy plating (hereinafter referred to as zinc plating) is most widely and generally used as a method for preventing rust of iron-based materials and parts. However, if zinc-plated iron-based materials and parts are used as they are, white rust, which is the rust of zinc, is immediately generated, so that it is general to further form a protective film. As a protective film usually applied to zinc plating, there are a phosphate film treatment and a chromate film treatment.

[0003] Phosphate coating treatment is disclosed in Japanese Patent Application Laid-Open No. Hei 3-10746.
As shown in No. 9, zinc ions and phosphate ions, which are film forming components heated to about 40 to 50 ° C. or about 75 ° C., and fluorine ions or complex fluoride ions as etching agents or film densifying agents are essential. This is a process in which a film is formed by immersion in a treatment liquid as a component, washed with water, and then dried. The surface morphology of the film obtained by this method is a severe unevenness generated so that the needle-like crystals of zinc phosphate are folded, and this surface morphology improves the adhesion of the coating which is the purpose of this film or Contributes to the improvement of corrosion resistance after painting. However, this film has a remarkable lack of rust prevention (corrosion resistance) when not painted, and has a poorly decorative appearance with a matte gray to grayish white appearance. However, there is a disadvantage that it is not suitable for partially painted products and products that are not coated. In addition, the phosphate film does not form unless it contains fluorine ions or complex fluoride ions, so that these materials are essential components, but these materials are highly corrosive and are also emission control substances. Further, it has a drawback that the processing temperature is high and equipment and cost for heating are required.

On the other hand, the chromate film treatment is classified into three types: electrolytic chromate treatment, coating type chromate treatment, and reaction type chromate treatment. The chromate treatment is applied not only to zinc but also to aluminum, cadmium or magnesium. The chromate film has better corrosion resistance in unpainted state than the phosphate film.However, the chromate treatment uses harmful hexavalent chromium. In recent years, it has been a serious problem because it has an adverse effect on the environment. This is a difficult problem since the chromate film is a film exhibiting corrosion resistance due to hexavalent chromium in the film. As another problem, electrolytic chromate treatment is always accompanied by the problem of rotating because a chromate film is formed by electrolysis, and is a big problem especially when performing processing on component materials that have complicated shapes unlike steel plates. . Chromic acid mist generated during electrolysis can be a more serious pollution problem than other methods. The coating type chromate treatment is a method in which an acidic aqueous solution containing chromic acid as a main component is applied to a metal surface and then heated and dried without washing with water. Since it is a coating type, it is not suitable for complicated shapes like electrolytic chromate, and there is a limit to coating with a uniform thickness and it is not washed with water, so the processing appearance is uneven like a phosphate film, The use of a single substance in terms of aesthetics is unsatisfactory because it does not meet the needs of the user, and is generally used as a coating base like a phosphate coating. On the other hand, the reactive chromate has uniform appearance and stable corrosion resistance and is often used alone as well as a coating base, but it has a problem of hexavalent chromium pollution.

Various inventions have been filed for solving the pollution problem of hexavalent chromium.
And Japanese Patent Application Laid-Open No. 9-53192.
Although these inventions can be noted in that they do not use hexavalent chromium, their practical performance is not satisfactory. For example, in a salt spray test specified in JIS Z 2731, the corrosion resistance stably exhibited is about 12 to 84 hours, and is 1/20 to 1 times that of commonly used colored chromate or black chromate (hexavalent chromium). / 2 or less. In addition, since these films do not have the ability to suppress the decrease in corrosion resistance at the time of film damage, which is called self-healing property, cross-cutting or extrusion with a knife to the test piece,
In case of damage due to bending, JIS Z 273
The corrosion resistance in the salt spray test specified in 1 is less than 24 hours (see Examples below). As an even greater problem, these costs are 5-10 times less than conventional colored chromates.
It is twice as many and industrially difficult.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to form a protective film on a surface of zinc or a zinc alloy without using harmful hexavalent chromium and having a uniform and good appearance and corrosion resistance. The formation of a film. In particular, in the coating type, it is difficult to obtain a protective film on a galvanized iron product other than a steel sheet which is practically difficult to treat industrially, and it has been an obstacle to the practical application of the alternative technology that has been invented so far. The main goal is to achieve cost performance.

[0007]

Means for Solving the Problems In order to solve the problems in the prior art, the inventors of the present invention have conducted intensive studies and as a result, have found that a rust-preventive film and a silicon compound which do not belong to the conventional phosphate film or chromate film are mainly used. In addition to solving the problem of hexavalent chromium, a rust-preventive protective film superior to the conventional chromate treatment and phosphate treatment was obtained by combining the protective film described above.

(1) Trivalent chromium ions in an amount of 0.01 to 1
A metal rust-preventing film-forming composition containing 0.1 g / L of phosphate ions and 0.1 to 200 g / L of nitrate ions; and (2) 0.1 g of trivalent chromium ions.
01 to 100 g / L and chlorine, fluorine, sulfate ions,
A composition for forming a metal rust-preventive film containing 0.1 to 200 g / L of one selected from the group consisting of nitrate ions and acetate ions; (3) the composition of (1) or (2), further comprising a silicon compound Or a composition for forming a metal anticorrosive film containing phosphoric acid, (4) a metal protective film containing 0.01 to 400 g / L of a silicon compound as silicon and 0.01 to 200 g / L of an alkali hydroxide. Forming composition, or (5)
The metal of (3) or (4), wherein the silicon compound is at least one silicon compound selected from the group consisting of sodium silicate, potassium silicate, lithium silicate, and colloidal silica having a particle size of 500 nm or less; By forming a coating on the surface of zinc, aluminum, magnesium, iron, nickel, cadmium, silver, copper or their alloys, the composition for forming a protective coating has a beautiful glossy appearance and excellent appearance without using hexavalent chromium A rust-proof coating having excellent corrosion resistance can be formed. On the other hand, (a) a method of forming a metal protective film using the composition of (1), (2) or (3), (b) forming a rust-preventive film on the surface of the metal,
The composition of (4), a silicon compound-containing aqueous solution or a pH of 8
A method for forming a metal rust-preventive protective film by dipping in the above aqueous solution to form a protective film, and (c) the metal rust-protective protective film according to (b), wherein the rust-preventive film is formed by the method of claim (a). Forming method, (d) the silicon compound is at least one silicon compound selected from the group consisting of sodium silicate, potassium silicate, lithium silicate, and colloidal silica having a particle size of 500 nm or less (a), (b) Or (c) a method for forming a metal rust-preventive protective film, (e) zinc, aluminum, magnesium, iron, nickel, cadmium, silver, copper or an alloy thereof by any of the methods (a) to (d). By the method of forming a rust preventive or protective film, a practical rust preventive protective film can be obtained which has not only improved corrosion resistance but also an ability to suppress a decrease in corrosion resistance when the film is damaged.
Further, according to the present invention, a coating mainly composed of a substance derived from trivalent chromium and phosphoric acid or a coating containing at least one of a substance derived from nitric acid, a substance derived from a silicon compound, and a substance derived from an alkali hydroxide is provided. The zinc or zinc alloy base member has a beautiful glossy appearance and excellent corrosion resistance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention are as follows. First, the treatment liquid for forming the rust preventive film of the present invention is an aqueous solution containing trivalent chromium ions, phosphate ions and nitrate ions and having a pH of 0.1 to 6.0. Although the exact behavior of each component is unknown, trivalent chromium ions and phosphoric acid are presumed to be the components that form the skeleton of the film, and nitrate ions suppress the ionization of phosphate ions in the solution, stabilizing the solution. It is presumed that this contributes to the formation of a smooth film by ensuring that the surface of the zinc is properly etched. The total amount of trivalent chromium ions in the treatment liquid is 0.01 to 100 g / L, preferably 0.5 to 80 g / L. If the amount is less than this, it is difficult to form a good film, and the film is not formed, or the required function cannot be obtained. On the other hand, if the amount is larger than this, the appearance and gloss of the film are reduced, and the economical loss due to pumping is increased, which is not appropriate. Chromium (III) acetate as a source of trivalent chromium
, Chromium (III) nitrate, chromium (III) chloride, chromium sulfate
(III), chromium (III) acid and the like, but the source is not particularly limited thereto. The total amount of phosphate ions in the treatment liquid is 0.1 to 200 g / L, and preferably contains 1 to 90 g / L. If the amount is less than this, it is difficult to form a good film, and the film is not formed, or the required function cannot be obtained. On the other hand, if the amount is larger than this, the appearance and gloss of the film are reduced, and the economical loss due to pumping is increased, which is not appropriate. The nitrate ion in the processing solution is 0.01 to 100 g / L
And preferably contains 1 to 50 g / L. If the amount is smaller than this, the stability of the liquid is lowered or the film formation rate becomes unstable. If the amount is larger, the economic loss due to pumping is large.

The pH of the processing solution is 0.1 to 6.0.
And preferably 0.5 to 4.0. If it is lower than this, it is difficult to form a uniform film, and if it is higher, the corrosion resistance tends to be slightly lowered. As a chemical used for adjusting the pH, an acid such as nitric acid or sulfuric acid may be added when it is high, and an alkali such as ammonia or sodium hydroxide may be added when it is low, but the added chemical is not limited thereto. There are no particular restrictions on the processing conditions for forming the rust-preventive film, and the conditions for performing a general reactive chromate treatment (liquid temperature 20 to 30 ° C., processing time 20
〜60 seconds, with agitation), treatment time of 250 seconds, immersion without agitation, and a wide range of conditions.
It is also possible to form a film by electrolysis. Even when the current density is low, a film is formed. However, in the present invention, since the film is formed without electrolysis, it is difficult to discriminate between the film formation by the electrolysis and the film formation by the reaction, and the lower limit of the current density cannot be defined. When it is high, the appearance defect called burn or kogation tends to occur in the high current density portion. If the treatment time is short, no film is formed, or even if it is formed, the thickness is insufficient, so that the corrosion resistance is poor. When it is long, a matte appearance defect sometimes occurs. Excessive processing time also significantly reduces productivity.

Further, 0.01 to 100 g / L, preferably 0.5 to 10 g / L of trivalent chromium ion and 0.0
After forming a rust-preventive film with a liquid composition containing 1 to 100 g / L, preferably 1 to 10 g / L, containing one kind selected from the group consisting of chlorine, fluorine, sulfate ion, nitrate ion and acetate ion, Furthermore, 0.01 to 300 g /
By forming a protective film using a liquid composition containing a silicon compound containing silicon of L, corrosion resistance comparable to that of a conventional colored chromate can be obtained. The addition of a silicon compound or phosphoric acid to the liquid composition is effective for improving and stabilizing corrosion resistance, and the amount is 1 to 200 g / L.
The degree is appropriate.

Next, the liquid protective film composition containing a silicon compound as a main component for forming the protective film is described in detail as silicon in an amount of 0.01 to 400 g / L, preferably 2 to 10 g / L.
It contains 0 g / L of a silicon compound and 0.01 to 200 g / L of caustic alkali. The silicon compound is a component constituting the skeleton of the film, and if the amount is small, the film does not form or does not exhibit sufficient performance even if it forms. If the amount is large, the economic loss due to pumping is large, and gloss may not be obtained in appearance. Availability as a silicon compound,
Judging comprehensively cost, performance, etc., sodium silicate, potassium silicate, lithium silicate, or average particle size 500n
m or less colloidal silica is preferred. There is no particular limitation on the processing conditions for forming the protective film, and the processing can be performed under the same conditions as those of the above-described trivalent chromium ion-containing composition (solution temperature: 20 to 30 ° C., processing time: 20 to 60 seconds, with stirring, etc.). It can be processed even at a liquid temperature of around 60 ° C., and has a wider condition range. If the treatment time is too short, no film is formed, or even if it is formed, the thickness is insufficient and the corrosion resistance is poor. If it is too long, a matte appearance defect sometimes occurs. Excessive processing time also significantly reduces productivity.

The combination of the composition for forming a rust-preventive film and the composition for forming a protective film solves the problem of deterioration of corrosion resistance at the time of film damage, which could not be solved by conventional techniques. In the case of a trivalent chromium ion-containing composition, even if the composition has a performance of 144 to 192 hours in a salt spray test in the case of a trivalent chromium ion-containing composition, even if it has a performance of 144 to 192 hours, if the film is damaged, it does not exceed 24 hours Will drop. In addition, a composition containing a silicon compound as a main component is referred to as “Molybdate-Based
Aiternatives to Chromating As a Passivation Treat
ment for Zinc "Plating and Surface Finishing, Nov.
A composition described in 1994, which has a specific molar ratio of molybdic acid to phosphoric acid, is disclosed in Japanese Patent Application Laid-Open Nos.
No. 53192, etc., the corrosion resistance in the salt spray test when the coating is damaged is only about 24 hours, but the combination of the present invention is 10 times or more.
Corrosion resistance of about 0 hours is obtained, and the effect is great. The performance of the conventional chromate under the same conditions is 72 to 144 hours, and the effect of the present invention greatly exceeds that of the conventional technology.

The rust preventive coating of the present invention does not use harmful hexavalent chromium by using the above-mentioned acidic aqueous solution, and sometimes uses the same processing equipment and processing conditions as conventional reactive chromate.
It is possible to form an insoluble strong film on the zinc surface by the treatment method. As a result, not only general users who are concerned about elution of hexavalent chromium from processed products, but also the health effects of chromate manufacturers and chromate processors who have been exposed to the hazards of chromate and the effects on wild animals The problem can be solved.

Chromate treatment and phosphate treatment are known as treatment methods similar to the rust-preventing film forming method of the present invention. However, the present invention provides various methods such as liquid composition, appearance, anticorrosion mechanism and treatment conditions. It is considered that they do not belong to any of them. That is, the chromate treatment is originally a general term for treatment using an aqueous solution containing hexavalent chromium represented by chromic acid, and the corrosion resistance depends on the amount of hexavalent chromium in the film.
Considering this definition, first, the present invention is not a chromate treatment because it does not contain hexavalent chromium. Next, since the coating does not contain hexavalent chromium, it is not a chromate because it does not have an anticorrosion mechanism dependent on the amount of hexavalent chromium in the coating. In addition, the chromate film has significantly reduced corrosion resistance when exposed to heat, whereas the film of the present invention has a small decrease in corrosion resistance due to heating. From this, it can be said that the film of the present invention is different from the conventional chromate film in the corrosion prevention mechanism, and the present invention is different from the chromate treatment.

As described in JP-A-3-107469, the phosphate treatment on zinc is carried out by heating to about 40 to 50 ° C. or about 75 ° C., zinc ion as a film forming component and phosphoric acid. The present invention is a process of immersing in a treatment solution containing an ion, an etching agent (a chemical reaction initiator) or a fluoride ion or a complex fluoride ion as a film densifying agent as an essential component, forming a film, washing with water, and then drying. Is different from the phosphate film in the liquid composition and the processing method. That is, the liquid composition is completely different in that zinc as a film forming component and fluorine ion or complex fluoride ion as an etching agent are not required. In the case of a phosphate film, if these components are missing, no film is formed. In addition, phosphate film is 4
In contrast to the necessity of heating at 0 to 75 ° C., the present invention can be processed at normal temperature (20 to 25 ° C.), and both are different even under the processing conditions. When compared in terms of performance, the phosphate film has an off-white appearance and has only a corrosion resistance of not more than 24 hours until the occurrence of white rust in a salt spray test, whereas the present invention shows a uniform and glossy appearance and a salt spray test. Shows corrosion resistance of 120 hours or more until the occurrence of white rust. In the phosphate film treatment, a dilute chromic acid aqueous solution treatment, which is generally called sealing or post-treatment, is performed to improve the corrosion resistance. However, even with this treatment, the corrosion resistance up to the generation of white rust is less than 24 hours.

Further, it is clear from the electron micrograph of the rust preventive film shown in FIG. 1 that the rust preventive film of the present invention is different from the phosphate film. That is, the surface of the phosphate film is entirely covered with crystals (Practical Surface Technology, Vol. 35,
No. 1, p23, photograph 2 (1988)), no crystals can be confirmed on the surface of the rust-proof coating of the present invention. As described above, the rust-preventive film of the present invention is completely different from the conventional phosphate film treatment and chromate film treatment even when the liquid composition, anti-corrosion mechanism, surface morphology, treatment conditions, appearance, etc. are compared and examined from various viewpoints. ing.

By combining this new rust-preventive film with the protective film mainly comprising the silicon compound of the present invention,
In addition to simply solving the problem of pollution of hexavalent chromium, it is possible to provide a protective film having better corrosion resistance than before. That is, the composition is not limited to the trivalent chromium-containing composition of the present invention, and the compositions having a specific molar ratio of molybdic acid and phosphoric acid described in the above-mentioned documents, JP-A-52-92936, JP-A-9-53192, and the like. Since the anti-corrosion film using no hexavalent chromium does not have the self-healing ability referred to as the conventional chromate film, if the film is damaged, the corrosion resistance in the salt spray test is less than 24 hours, which is not practical. In order to compensate for this, a composition having a specific molar ratio of molybdic acid and phosphoric acid described in the literature, a rust preventive film disclosed in JP-A-52-92936, JP-A-9-53192, etc., and a silicon compound of the present invention Even when a protective film mainly composed of styrene is combined, the corrosion resistance in a salt spray test when the film is damaged is only about 24 hours. However, only in the case of the combination of the present invention, the corrosion resistance of about 240 hours corresponding to 10 times the above is obtained specifically, and the effect is more than expected. The performance of the conventional chromate under the same conditions is 72 to 144 hours, and the effect of the present invention is far superior to the conventional technology.

The protective rust preventive film of the present invention has the ability to suppress a decrease in corrosion resistance when the film is damaged. Therefore, the protective rust preventive film suppresses the generation of rust when the film is damaged due to stepping stones in automobile parts and the like, and is very important in industry. Performance. Furthermore, the film obtained by the present invention is excellent in heat resistance and corrosion resistance, and solves the problem of deterioration in corrosion resistance due to heat treatment, which was a drawback of the conventional chromate film. When this treatment is carried out by immersion, the economical advantage that the conventional treatment type chromate treatment equipment can be used as it is is also a feature of this method.

[0020]

The present invention will be described below with reference to examples. In the test, the test pieces were subjected to appropriate pretreatments such as degreasing and immersion in nitric acid, and then each of the following treatments was performed. Test pieces are 3 each
Were produced. One piece is 5mm by Erichsen extruder
Was extruded. One was cross-cut with a knife to reach the substrate. All the specimens together with the remaining one were put into a salt spray tester. Tables 1 and 2 show the time until the occurrence of white rust.

EXAMPLE 1 A zinc-plated iron plate (50 × 100 × 1 mm) was treated with an aqueous solution containing 8 g / L of chromium nitrate, 1 g / L of 67.5% nitric acid and 5 g / L of ammonium fluoride with ammonia at pH 2.5.
Immersed in the treatment solution adjusted for 40 seconds, washed with water after forming the film,
After drying, the treatment liquid containing 25 g / L of No. 3 sodium silicate
A test piece was prepared by immersion for 0 seconds. Each liquid temperature is 2
5 ° C and 35 ° C. Example 2 A zinc-plated iron plate (50 × 100 × 1 mm) was prepared using 5 g / L of chromium chloride, 5 g / L of ammonium fluoride, and 75%
An aqueous solution containing 2 g / L of sulfuric acid was immersed in a treatment solution adjusted to pH 2.0 with ammonia for 1 minute to form a film. Then, the mixture was treated at 40 ° C. in a treatment solution containing 130 g / L of No. 3 sodium silicate and 5 g / L of potassium hydroxide. A test piece was prepared by immersion for 50 seconds. Example 3 A galvanized iron plate (50 × 100 × 1 mm) was subjected to pH
Immersion in a treatment solution containing 5 g / L of 1.6 chromium acetate, 1 g / L of hydrofluoric acid, 2 g / L of phosphoric acid, and 2 g / L of sulfuric acid at 25 ° C. for 2 minutes, after forming a film, 50 g / L of potassium silicate, A test piece was prepared by immersion in a treatment solution containing 20 g / L of a conductive soda at 50 ° C. for 30 seconds.

Example 4 A zinc-plated iron plate (50 × 100 × 1 mm) was subjected to 10 g / L of chromium acetate, 2 g / L of 60% nitric acid, and 3 g of borofluoric acid.
/ L, an aqueous solution containing 10 g / L of sodium silicate was immersed in a treatment solution adjusted to pH 2.0 with ammonia for 1 minute to form a film, and then 100 g / L of No. 3 sodium silicate and 8 g / L of sodium hydroxide.
Was immersed in a treatment solution containing at 40 ° C. for 20 seconds to prepare a test piece. Example 5 A galvanized iron plate (50 × 100 × 1 mm) was subjected to pH adjustment.
1.8 g / L chromium nitrate, 1.5 g / L hydrochloric acid, 6
It is immersed in a processing solution containing 1 g / L of 0% nitric acid and 20 g / L of No. 3 sodium silicate for 40 seconds, and after forming a film, 120 g / L of colloidal silica, 2 g / L of potassium hydroxide, and 5 g / L of sodium hydroxide.
Was immersed in a treatment solution containing at 50 ° C. for 30 seconds to prepare a test piece. Example 6 A galvanized iron plate (50 × 100 × 1 mm) was subjected to pH
2.6 g of chromium sulfate 15 g / L, phosphoric acid 5 g / L, acetic acid 8 g / L, hydrofluoric acid 1 g / L, sodium silicate 20 g / L for 35 seconds, after forming a film, potassium silicate 80 g / L L, a treatment solution containing 7 g / L of potassium hydroxide
A test piece was prepared by immersion for 30 seconds.

Example 7 A zinc-plated iron plate (50 × 100 × 1 mm) was prepared by adding 18 g / L of chromium nitrate, 20 g / L of 75% phosphoric acid, and 67.5%.
An aqueous solution containing 15 g / L of nitric acid is adjusted to pH 1.8 with ammonia.
Immersed in the treatment solution adjusted for 90 seconds, washed with water after forming the film,
It dried and the test piece was produced. An electron micrograph of the formed film is shown in FIG. Example 8 A test piece prepared in the same manner as in Example 7 was further subjected to a heat treatment at 200 ° C. for 1 hour to obtain a test piece. Example 9 Zinc-iron alloy plated iron plate (50 × 100 × 1 mm)
To 15 g / L of chromium nitrate, 25 g / L of 75% phosphoric acid,
An aqueous solution containing 67.5% nitric acid (25 g / L) was immersed in a treatment solution adjusted to pH 2.0 with ammonia for 1 minute to form a film, and then a treatment solution containing No. 3 sodium silicate 130 g / L and potassium hydroxide 5 g / L The sample was immersed in the sample at 40 ° C. for 50 seconds to prepare a test piece.

Example 10 A galvanized iron plate (50 × 100 × 1 mm) was treated with a pH
1.6 g of chromium nitrate 10 g / L, phosphoric acid 10 g / L, 6
Immersion in a processing solution containing 10 g / L of 0% nitric acid for 2 minutes, after formation of a film, potassium silicate 50 g / L, potassium hydroxide 20 g / L
Was immersed in a treatment solution containing at 30 ° C. for 30 seconds to produce a test piece. Example 11 A zinc-plated iron plate (50 × 100 × 1 mm) was treated with an aqueous solution containing 20 g / L of chromium acetate, 25 g / L of 60% nitric acid, and 35 g / L of 75% phosphoric acid at pH 2.0 with ammonia. After immersion for 2 minutes to form a film, 4 g in a treatment liquid containing 100 g / L of sodium silicate No. 3 and 5 g / L of potassium hydroxide
A test piece was prepared by immersion at 0 ° C. for 50 seconds.

Example 12 A galvanized iron plate (50 × 100 × 1 mm) was adjusted to pH
1.0 g of chromium nitrate 15 g / L, phosphoric acid 25 g / L, 6
Immerse in a processing solution containing 18 g / L of 0% nitric acid for 2 minutes, and after forming a film, colloidal silica 120 g / L and potassium hydroxide 2 g
/ L, a treatment solution containing 5 g / L of caustic soda at 50 ° C.
The sample was immersed for 2 seconds to prepare a test piece. Example 13 pH of a galvanized iron plate (50 × 100 × 1 mm)
1.6 g of chromium nitrate 35 g / L, phosphoric acid 35 g / L, 6
After immersion in a treatment liquid containing 18 g / L of 0% nitric acid for 2 minutes and forming a film, a test piece was prepared by immersion in a treatment liquid containing 80 g / L of potassium silicate and 7 g / L of potassium hydroxide at 50 ° C. for 30 seconds. .

COMPARATIVE EXAMPLE 1 A galvanized iron plate (50) having no surface treatment
× 100 × 1 mm) as a test piece, and a salt spray test (JI
The time until the occurrence of white rust in SZ2371) was examined. Comparative Example 2 20 g / L of 35% hydrogen peroxide and 10 g / 62% of nitric acid
L, an iron plate (50 × 100 × 1 mm) galvanized with a treatment liquid having a pH of 1.3 containing 1.0 g / L of titanium sulfate was subjected to a chemical conversion treatment at a liquid temperature of 20 ° C. for 45 seconds. Comparative Example 3 30 g / L of 35% hydrogen peroxide and 15 g / 62% of nitric acid
L, colloidal silica 70 g / L, titanium sulfate 0.3 g
An iron plate (50 × 100 × 1 mm) galvanized with a pH 1.6 treatment solution containing / L was subjected to a chemical conversion treatment at a solution temperature of 20 ° C. for 45 seconds. After film formation, colloidal silica 100g
/ L, caustic potash 2 g / L, and caustic soda 5 g / L were immersed in a treatment solution at 50 ° C. for 30 seconds to prepare test pieces.

Comparative Example 4 50 g / L of 35% hydrogen peroxide, 5 g / L of 62% nitric acid,
Colloidal silica 100 g / L, titanium sulfate 0.3 g /
L, an iron plate (50 × 100 × 1 mm) galvanized with a treatment solution of pH 1.5 containing 15 g / L of 75% phosphoric acid was subjected to a chemical conversion treatment at a liquid temperature of 20 ° C. for 45 seconds. After film formation,
A test piece was prepared by immersing in a treatment solution containing 120 g / L of colloidal silica, 7 g / L of potassium hydroxide, and 5 g / L of sodium hydroxide at 50 ° C. for 30 seconds. Comparative Example 5 A test piece was prepared by immersion in a treatment liquid containing 12.1 g / L of sodium molybdate and 14.7 g / L of 75% phosphoric acid at 60 ° C. for 2 minutes. Comparative Example 6 After immersion in a treatment solution containing 12.1 g / L of sodium molybdate and 14.7 g / L of 75% phosphoric acid at 60 ° C. for 2 minutes, 90 g / L of colloidal silica, 10 g / potassium potassium
L was immersed in a treatment solution containing 2 g / L of caustic soda at 50 ° C. for 30 seconds to prepare a test piece.

Comparative Example 7 0.1 mol / L of sodium molybdate, 0.1 mol of phosphoric acid.
After immersion in a treatment solution containing 15 mol / L at 60 ° C. for 2 minutes, colloidal silica 90 g / L, potassium hydroxide 10 g / L
L was immersed in a treatment solution containing 2 g / L of caustic soda at 50 ° C. for 30 seconds to prepare a test piece. Comparative Example 8 Sodium vanadate 15 g / L, 75% phosphoric acid 20 g
/ L, 35 g / L of sodium nitrate, immersed in a treatment solution of pH 2 at 30 ° C. for 2 minutes, and then colloidal silica 90 g /
L, 15 g / L of caustic potash and 9 g / L of caustic soda were immersed at 50 ° C. for 30 seconds to prepare test pieces.

Comparative Example 9 A commercially available phosphate coating solution (Palbond 3300) heated to 70 ° C. after surface conditioning of a galvanized iron plate (50 × 100 × 1 mm) with Preparen Z (Nippon Parkerizing Co., Ltd.) : 15 for Japan Parkerizing Co., Ltd.
After dipping for 2 seconds and forming a film, the film was washed with water, further subjected to post-treatment with Paren 1 (Nippon Parkerizing Co., Ltd.), and dried to prepare a test piece. Comparative Example 10 The test piece prepared in Comparative Example 4 was further subjected to No. 3 sodium silicate 11
A test piece was prepared by immersion in a treatment solution containing 0 g / L and 5 g / L of potassium hydroxide at 40 ° C. for 50 seconds.

Comparative Example 11 A test piece prepared in the same manner as in Comparative Example 2 was further subjected to a heat treatment at 200 ° C. for 1 hour to obtain a test piece. Comparative Example 12 A test piece prepared in the same manner as in Comparative Example 5 was further subjected to a heat treatment at 200 ° C. for 1 hour to obtain a test piece. Comparative Example 13 A test piece prepared in the same manner as in Comparative Example 8 was further subjected to a heat treatment at 200 ° C. for 1 hour to obtain a test piece.

[0031]

[Table 1]

[0032]

[Table 2]

[Brief description of the drawings]

FIG. 1 is an electron micrograph of a rust preventive film (Example 7).

Claims (12)

[Claims] 1. The method according to claim 1, wherein the trivalent chromium ion is contained in an amount of 0.01 to 100.
g / L, a composition for forming a metal rust-preventive film containing 0.1 to 200 g / L of phosphate ions and 0.01 to 100 g / L of nitrate ions. 2. The method according to claim 1, wherein the trivalent chromium ion is contained in an amount of 0.01 to 100
g / L and one selected from the group consisting of chlorine, fluorine, nitrate ions, sulfate ions and acetate ions in an amount of 0.1 to
A composition for forming a metal anticorrosive film containing 200 g / L. 3. The composition for forming a rust-preventive metal film according to claim 1, further comprising a silicon compound or phosphoric acid. 4. A composition for forming a protective film of a metal, comprising 0.01 to 400 g / L of a silicon compound as silicon and 0.01 to 200 g / L of an alkali hydroxide. 5. The method according to claim 1, wherein the silicon compound is sodium silicate,
Potassium silicate, lithium silicate, and particle size 500 nm
The composition for forming a rust-preventive or protective film of a metal according to claim 3 or 4, which is at least one silicon compound selected from the group consisting of the following colloidal silicas. 6. Zinc, aluminum, magnesium,
The composition for forming a rust-preventive or protective film of a metal according to any one of claims 1 to 5, which forms a film on the surface of iron, nickel, cadmium, silver, copper or an alloy thereof. 7. A method for forming a metal rust preventive film using the composition according to claim 1, 2 or 3. 8. After forming a rust preventive film on the surface of the metal,
A method for forming a metal rust-preventive protective film, comprising forming the protective film by immersing the composition according to claim 4 or a silicon compound-containing aqueous solution or an aqueous solution having a pH of 8 or more. 9. The method according to claim 8, wherein the rust-preventive film is formed by the method according to claim 7. 10. The method according to claim 1, wherein the silicon compound is sodium silicate, potassium silicate, lithium silicate, and has a particle size of 500.
The method for forming a metal rust-preventive protective film according to any one of claims 7 to 9, wherein the method is at least one silicon compound selected from the group consisting of colloidal silica having a diameter of at most nm. 11. The rust-preventive protective film for a metal according to claim 7, wherein the metal is zinc, aluminum, magnesium, iron, nickel, cadmium, silver, copper, or an alloy thereof. Forming method. 12. A coating mainly containing a substance derived from trivalent chromium and phosphoric acid or a coating containing at least one of a nitric acid-derived substance, a silicon compound-derived substance, and an alkali hydroxide-derived substance. A member made of a zinc or zinc alloy base material, characterized in that: