JP2003313675A - Agent for forming rust preventive film on metal, and forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a coating film having both a uniform and adequate appearance and corrosion resistance without using harmful hexavalent chromium, when forming a protective coating on the surface of zinc or a zinc-base alloy, and for satisfying factors of corrosion resistance, design characteristics and the cost, which hinder a substitutional technology of the conventional trivalent-chromium-based rust preventive coating from being practically used. <P>SOLUTION: This method forms the rust-preventive coating film by using a liquid composition including (A) trivalent chromium ions, (B) one or more elements selected from the group consisting of Mo, W, Ti, Zr, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, and alkaline earth metals, (C) one or more elements selected from the group consisting of Ni, Pd, Pt, Sc, Y, V, Nb, Ta, Cu, Ag, and Au, (D) one or more kinds selected from the group consisting of Cl, fluorine, sulfate ions, and nitrate ions, and (E) one or more kinds selected from the group consisting of Si, Al, and organic acid. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to the protection of various metals, and more particularly to zinc or zinc alloys, and to the rust prevention of metal materials plated with these metals. The present invention relates to a liquid rust preventive used for rust prevention of iron parts plated with zinc-based alloy and rust preventive using the same.

[0002]

2. Description of the Related Art Generally, zinc or zinc-based alloy plating (hereinafter referred to as zinc plating) is most widely used as a rust preventive method for iron-based materials and parts. However, zinc-plated iron-based materials / parts immediately produce white rust, which is the rust of zinc, if they are used as they are. Therefore, it is common to further form a protective film. Chromate film treatment is generally used as a protective film that is usually applied to zinc plating, and the chromate film treatment is further classified into three types: electrolytic chromate treatment, coating type chromate treatment, and reactive type chromate treatment. Chromate treatment is not limited to zinc, but can be applied to aluminum, cadmium, magnesium, etc.

Chromate coatings are widely used because they are inexpensive and can easily obtain practical corrosion resistance. However, all chromate treatments use hexavalent chromium, which is harmful, and elute not only from the treatment liquid but also from the treated product. Hexavalent chromium has become a big problem in recent years because it has an adverse effect on the human body and the environment. This is a difficult problem as long as the chromate film is a film that exhibits corrosion resistance due to the hexavalent chromium in the film.

Various inventions have been filed so far in order to solve the pollution problem of hexavalent chromium.
-92836, JP-A-57-145987, JP-A-9-
53192, JP-A-57-181379, JP-A-50-
1934 and Japanese Patent Laid-Open No. 2000-234177. It can be noted that these inventions do not use hexavalent chromium, but their practical performance is not satisfactory. For example, J
In the salt spray test prescribed by ISH2731, the corrosion resistance stably exhibited is around 12 to 84 hours, which is only 1/20 to 1/2 or less of the commonly used colored chromate or black chromate. . Further, since these coatings do not have the ability to suppress deterioration of corrosion resistance at the time of film damage called self-repairing property, when the test piece is damaged by cross cutting with a knife or by extrusion / bending, the corrosion resistance according to JIS Z 2731 is 24 Less than an hour In addition, the obtained color tone is limited, and the design is inferior. A more serious problem is that these costs are 5 to 10 times higher than those of conventional colored chromates, which may be difficult to establish industrially.

As a concrete problem, Japanese Patent Application Laid-Open No. 52-928.
In No. 36, treatment of zinc or a zinc alloy with an aqueous solution of one or more selected from the group consisting of Ti and phosphoric acid, phytic acid, tannic acid or hydrogen peroxide is a feature. The appearance after treatment is almost colorless and has very low corrosion resistance. Since it is a treatment on a steel plate, which is complicated and requires a high temperature for a long time, even if the coating is baked, the corrosion resistance by salt spray is only about 240 hours. JP-A-50-1934 describes a colorless glossy chromate composition of zinc or a zinc alloy, which comprises a mineral acid, a compound capable of generating trivalent chromium ions, a carboxylic acid and optionally a reducing agent. With this composition, it is possible to obtain a uniform glossy chromate-like appearance on zinc or a zinc alloy, but the corrosion resistance in salt spray is a very low performance of 48 hours or less until the occurrence of white rust. The composition was poor in stability. Japanese Patent Application Laid-Open No. 61-587 discloses a composition containing trivalent chromium ions, a silicate, a fluoride and an acid. The film obtained by this composition also has a uniform glossy chromate-like appearance. The corrosion resistance is a low performance of 24 hours or less before the occurrence of white rust. Japanese Patent Laid-Open No. 2000-234177 describes a chemical conversion treatment liquid for zinc or a zinc alloy, which is composed of a trivalent chromium compound and a titanium compound, a cobalt compound, a tungsten compound and a silicon compound. A chemical conversion coating with relatively high corrosion resistance is to be obtained with this treatment liquid, but there are large variations for industrial commercialization, the treatment conditions are relatively high for a long time, and the drying temperature is higher than before. In addition to the long period of time, there is a problem in that the stability of the treatment liquid described is poor and precipitation occurs in a few days. The resulting coating, like the others, has a glossy chromate-like appearance. JP-A-61-1119677 describes an acidic composition containing trivalent chromium and iron, cobalt, nickel, molybdenum, manganese, aluminum, lanthanum, cerium, lanthanide, a mixture thereof, and nitric acid. Further, a composition containing an organic carboxylic acid and a silicate is described. Although this composition can provide a uniform glossy chromate-like appearance on zinc or a zinc alloy, the corrosion resistance in salt spray was not sufficient and white rust was generated for about 72 hours. In addition, a composition using an organic acid is poor in stability of the liquid, and there is a problem that the appearance of the treatment and the pH of the liquid change in several days to several weeks. As described above, the conventional technologies generally lack corrosion resistance, single appearance (weak interference color like gloss chromate, achromatic appearance), lack of stability, cost performance (low performance obtained depending on processing conditions). I had a problem of lowness.

[0006]

The object of the present invention is to form a protective film on the surface of a metal, particularly zinc or a zinc alloy, without using harmful hexavalent chromium, and to have a uniform and good appearance and corrosion resistance. It is to form a film. In particular, it is to obtain excellent corrosion resistance, designability, and cost performance, which are obstacles to the practical application of the alternative technologies that have been invented so far.

[0007]

In order to solve the problems in the prior art, the inventors of the present invention have conducted diligent research, and as a result, various metals are mainly used, and an organized specific group is appropriately combined with an appropriate combination. It has been found that by compounding, it has unprecedented excellent corrosion resistance, designability, and cost performance. That is, the present invention includes (A) trivalent chromium ions, (B) Mo, W, Ti, Zr, Mn, and T.
one or more selected from the group consisting of c, Re, Fe, Ru, Os, Co, Rh, Ir, and alkaline earth metals, (C) N
i, Pd, Pt, Sc, Y, V, Nb, Ta, Cu, A
g, one or more of the group consisting of Au, (D) one or more of the group consisting of chlorine, fluorine, sulfate ion, and nitrate ion, (E) a group consisting of Si, Al, and an organic acid 1
A rust preventive film forming agent comprising a liquid composition containing at least one kind and a method of forming a rust preventive film on a metal using the same.
The liquid composition may further include a stabilizer. The metal to which the present invention is applicable is a metal selected from zinc, aluminum, magnesium, copper, nickel, chromium, iron, tin and alloys thereof.

In the present invention, after the rust preventive film is formed by the above liquid composition, it is further brought into contact with a liquid composition containing at least one selected from the group consisting of Si, resin and wax. A method for forming a protective film is provided. As a result, it has been found that, in addition to the above-mentioned further improvement of the characteristics, the coefficient of friction can be controlled and the corrosion resistance comparable to that of the conventional colored chromate can be obtained.

[0009]

More specifically, the liquid composition of the present invention contains 0.01 to 150 g / l, preferably 0.1 to 50 g / l, of trivalent chromium ions per liter of water, and 0.1. 0
1-100 g / l, preferably 0.1-40 g / l M
o, W, Ti, Zr, Mn, Tc, Re, Fe, Ru,
One or more of Os, Co, Rh, Ir and alkaline earth metal, and 0.001 to 200 g / l, preferably 0.01 to 5
0g / l Ni, Pd, Pt, Sc, Y, V, Nb, T
at least one of a, Cu, Ag and Au, and 0.05 to 200
g / l, preferably 0.1 to 100 g / l of one or more kinds of chlorine, fluorine, sulfate ion and nitrate ion, and 0.1 to 3
00 g / l, preferably 0.5 to 100 g / l Si, A
1, a method of forming a rust preventive film with a liquid composition containing at least one organic acid, or a method of forming a protective film with a liquid composition further containing at least one of Si, a resin and a wax. It has been found that corrosion resistance equal to or higher than that of colored chromate can be obtained, and an appearance other than that of glossy chromate can be obtained. If the amount of each component is less than these ranges, the effect cannot be obtained. On the other hand, if the amount is excessive, the effect will reach its limit and not only the economical loss will be large, but also excessive formation of the film may cause deterioration of corrosion resistance, which is not preferable.

If further added, trivalent chromium and Mo,
W, Ti, Zr, Mn, Tc, Re, Fe, Ru, O
The ratio of the group consisting of s, Co, Rh, Ir and alkaline earth metal is 1: 500 to 1: 0.002, preferably 1:10.
~ 1: 0.001, trivalent chromium and Ni, Pd, Pt, S
The ratio of the group consisting of c, Y, V, Nb, Ta, Cu, Ag and Au is 1: 500 to 1: 0.0002, preferably 1 :.
30-0.002, the ratio of the group consisting of trivalent chromium to Si, Al and organic acid is 1: 1000 to 1: 0.01, preferably 1:10 to 1: 0.02 for better corrosion resistance The film of can be stably obtained. Further, if a combination is selected, trivalent chromium and Mo, W, Ti,
Group consisting of Zr, Mn, Fe, Co, alkaline earth and N
The combination of i, Pd, Pt, Sc, V, Nb, Ta, and Au and the group consisting of Si and the organic acid and acid tends to show particularly high corrosion resistance.

There is no particular specification as to the method of supplying any metal, and in addition to inorganic salts such as chlorides, sulphates and nitrates, organic acid salts, oxo acids, oxo acid salts, etc. It is convenient because a component such as an acid ion can be supplied, and particularly, a sulfuric acid compound and a nitric acid compound have good corrosion resistance. Si
Other than these, Al and Al can be supplied as oxides or colloidal oxides. In addition, adding a stabilizer to the liquid composition is effective for stabilizing the corrosion resistance and design.

As the stabilizer, 0.1 to 100 g / l, preferably 0.5 to 50 g / l of a surfactant, hydrogen peroxide, a heterocyclic compound, ureas, aliphatic amines, acid amides, aminocarboxylic acids. Acids, ammonium salts, aliphatic sulfonic acids and aromatic aldehydes are effective. Particularly, nitrogen-containing compounds such as heterocyclic compounds, ureas, aliphatic amines, acid amides, aminocarboxylic acids and ammonium salts, and nitrogen-containing surfactants are preferable.

The content of Si and Al for forming the protective film is 0.01 to 500 g / l, preferably 1 to 300 g / l.
l is appropriate, and if it is insufficient, no effect will be obtained,
If it is excessive, a white appearance defect may occur. In both the rust preventive film and the protective film, the silicon compound is preferably sodium silicate, potassium silicate, lithium silicate, or colloidal silica having a particle size of 100 nm or less, more preferably 50 nm or less. As the aluminum compound, aluminum sulfate, aluminum chloride, alumina sol, aluminum stearate, aluminum silicate and the like are preferable.

The resin is not particularly limited, but among them, Teflon (registered trademark) resin, epoxy resin coating, acrylic resin coating, melamine resin, acrylic silica resin and acrylic Teflon resin are preferable. It is necessary to select an appropriate concentration depending on the corrosion resistance and appearance (gloss, liquid pool, unevenness) and the like, and 1 to 800 g / l, preferably 10 to 500 g / l is easy to obtain high corrosion resistance. Examples of the organic acid include succinic acid, malic acid, malonic acid, oxalic acid, acrylic acid, formic acid, acetic acid, tartaric acid, citric acid, glutamic acid, ascorbic acid, inosinic acid, carboxylic acids such as lactic acid. The content is 0.1 to 500 g / l, preferably 1 to 20
0 g / l is suitable. When the amount is insufficient, the effect cannot be obtained, and when the amount is excessive, the effect reaches the ceiling and economic loss is increased, and the appearance may be deteriorated. There are various waxes, but petroleum wax, polyurethane wax, polyethylene wax, polypropylene wax, and polyacrylic ester are preferable. Although it cannot be unconditionally specified depending on the required characteristics (friction coefficient, etc.), generally, if it is in the range of 0.01 to 200 g / l, it can be used with almost no influence on other characteristics.

The preferred treatment conditions for producing the rust-preventive coating with the liquid composition are: treatment time 5 to 90 seconds, treatment temperature 10 to 80 ° C., pH 1 to 4, more preferably treatment time 1
The treatment temperature is 5 to 60 seconds, the treatment temperature is 25 to 40 ° C., and the pH is 1.5 to 3. Preferable processing conditions for the protective film containing Si are a processing time of 1 to 60 seconds, a processing temperature of 5 to 80 ° C., and a pH.
7.5-14, more preferably 10-40 seconds processing time,
The treatment temperature is 15 to 60 ° C., the pH is 8 to 13, and the treatment temperature is 10 to 30 ° C. depending on the resin.

The protective film obtained by these combinations not only has a corrosion resistance equal to or higher than that of the colored chromate, but also a practical protective film to which the ability to suppress deterioration of corrosion resistance at the time of film damage is added. It has been found.
This corrosion resistance deterioration suppressing ability is, for example, an object that suppresses the generation of rust at the time of film damage due to flying stones in automobile parts and the like, which is a performance that could hardly be obtained with the invention so far, but is a very important performance in industry. Is. Further, it has become possible to obtain a uniform color tone, which has not been obtained in the past, and the designability has been improved. This method can perform a high temperature of 40 to 80 ° C. or a relatively long time of 45 to 90 seconds, but depending on the application, it has an economic merit that the conventional reaction chromate treatment equipment can be used as it is. It is also a feature. The treatment conditions for forming a film are those for performing conventional chromate treatment (liquid temperature 20 to 35 ° C., treatment time 20 to 4).
The treatment can be performed for 0 seconds, with stirring), and the treatment conditions for forming a protective film with a composition containing silicon, resin, and wax can be obtained by simply immersing at a liquid temperature of 20 to 50 ° C. for 20 to 40 seconds. Processing is very easy.

[0017]

By using the acidic aqueous solution specified in the present invention, it is possible to form a strong insoluble film on the zinc surface by the same treatment equipment, treatment conditions and treatment method as those of the conventional reactive chromate without using harmful hexavalent chromium. It is possible to generate. As a result, not only for general users who are concerned about elution of hexavalent chromium from treated products but also for the health effects of chromate manufacturers and chromate processors who have been exposed to the toxic effects of chromic acid, and the effects on wild animals. It becomes possible to solve the problem.

The trivalent chromium-containing composition selected from the group divided into five according to the present invention not only solves the pollution problem of hexavalent chromium, but also cannot be obtained by the conventional alternative techniques. It also becomes possible to provide the ability to control corrosion in the event of damage. That is, in the past, JP-A-52-9
2836, JP-A-50-1934, and JP-A-61-58.
7, JP-A-2000-234177, JP-A-61-119
Anticorrosion coatings that do not use hexavalent chromium such as 677 have been proposed. However, these coatings have no or very weak self-repair ability, which is said in conventional chromate coatings. Therefore, if the coatings are damaged, the corrosion resistance in a salt spray test is 24 to 7
It is about 2 hours and not practical. Also, as with the treatment of bolts and the like, a large amount of items with an appropriate weight are dropped or collide with each other (co-deviation during processing). Good performance was not exhibited on the line. In some cases, the composition lacks stability of the treatment liquid. It is considered that the reason why these problems can be solved by the present invention is that these conventional techniques do not satisfy all of the five groups shown in the present invention and lack some of them. Further, the present invention not only provides corrosion resistance higher than that of the prior art but also makes it possible to control the friction coefficient by adding wax or the like.

[0019]

EXAMPLES The present invention will be described below with reference to examples. In the test, the test piece was subjected to appropriate pretreatment such as degreasing and dipping in nitric acid, and then zinc plating (Zn) or zinc-iron alloy plating (Zn / Fe) was performed using a commercially available chemical (manufactured by Nippon Surface Chemical Co., Ltd.). ),
After applying any of zinc-nickel alloy plating (Zn / Ni) to a plating film thickness of 8-9 μm, using a rust preventive film forming agent having the composition (amount per 1 L of water) listed in Table 1, A rust-preventive film was formed according to the treatment temperature and treatment time conditions. For comparison, the same known composition was used to form an anticorrosion coating. For the evaluation, a salt spray test according to JIS Z 2301 was performed. The time when 5% of white rust is generated is shown. Those not particularly described did not show any change in the liquid appearance, pH, or treatment appearance after being left for 1 week.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C23C 22/40 C23C 22/40 22/50 22/50 22/52 22/52 22/53 22/53 22/56 22 / 56 22/57 22/57 22/58 22/58 (72) Inventor Hidero Susa 1136 Hagizono, Chigasaki City, Kanagawa Japan Surface Chemicals Co., Ltd. Chigasaki Factory F-term (reference) 4D075 BB73X CA33 DA06 DB01 DB05 EA07 EB18 EB22 EB33 EB42 EB56 EC02 EC07 EC33 4K026 AA01 AA02 AA06 AA07 AA09 AA11 BA06 BA08 BB08 CA13 CA18 CA19 CA27 CA28 CA29 CA30 CA31 CA32 CA33 CA38 CA39 CA41

Claims (8)

[Claims] 1. (A) Trivalent chromium ion, (B) M
o, W, Ti, Zr, Mn, Tc, Re, Fe, Ru,
One or more selected from the group consisting of Os, Co, Rh, Ir and alkaline earth metals, (C) Ni, Pd, Pt, Sc,
At least one member selected from the group consisting of Y, V, Nb, Ta, Cu, Ag and Au, (D) at least one member selected from the group consisting of chlorine, fluorine, sulfate ion and nitrate ion, (E) Si, A
1. A method for forming a metal anticorrosion film, which comprises forming the anticorrosion film with a liquid composition containing at least one member selected from the group consisting of 1 and an organic acid. 2. The method for forming a metal rust preventive film according to claim 1, wherein a film is formed with the liquid composition further containing a stabilizer. 3. After performing the method according to claim 1 or 2, further S
A method for forming an anticorrosive film of metal, which comprises contacting with a liquid composition containing at least one member selected from the group consisting of i, resin and wax. 4. The method for forming a metal rust preventive film according to claim 1, wherein the metal is zinc, aluminum, magnesium, copper, nickel, chromium, iron, tin and alloys thereof. 5. (A) Trivalent chromium ion, (B) M
o, W, Ti, Zr, Mn, Tc, Re, Fe, Ru,
One or more selected from the group consisting of Os, Co, Rh, Ir and alkaline earth metals, (C) Ni, Pd, Pt, Sc,
At least one member selected from the group consisting of Y, V, Nb, Ta, Cu, Ag and Au, (D) at least one member selected from the group consisting of chlorine, fluorine, sulfate ion and nitrate ion, (E) Si, A
1. A metal rust preventive film forming agent comprising a liquid composition containing at least one member selected from the group consisting of 1 and an organic acid. 6. The metal rust preventive film forming agent according to claim 5, wherein the film is formed with a liquid composition further containing a stabilizer. 7. The liquid composition according to claim 5 or 6 and S.
A combination of a liquid composition for forming a metal anticorrosive film, which is formed by a combination with a liquid composition containing at least one selected from the group consisting of i, a resin, and a wax. 8. The rust preventive film forming agent for a metal according to claim 5, wherein the metal is selected from zinc, aluminum, magnesium, copper, nickel, chromium, iron, tin and alloys thereof.