JPH11244781A - Rust stabilizing surface treatment method of steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rust stabilizing surface treatment method of steel which forms stable rust early without generating loose scale such as red rust and fluidized rust on the surface of weatherproof steel, common steel, or the like or on the surface of the rust layer even in a severely corrosive environment and does not deteriorate its appearance during and after the formation of the stable rust. SOLUTION: On the surface of steel or on the surface of rust of steel, a treating agent which contains 0.02-20 wt.% based on metal of at least one kind of compound selected from the compounds of Cu, Ni, Cr, Al, Mo, and P and the pH of which is adjusted at 1-6 is applied to form a dry film at least 0.01 μm in thickness, and an organic resin coating containing an ion and/or its compound forming a nearly insoluble salt with Cl<-> is applied to the dry film to form a dry, 1-100 μm thick film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for promoting the production of stable rust of steel in the anticorrosion surface treatment of steel used for bridges, steel towers, buildings, marine structures and the like. With the addition of alloy elements such as Mo, mainly so-called weather-resistant steel, when steel is used without painting, a weather-resistant stable rust layer having an anticorrosive protective action on the surface of the steel is promptly generated, The present invention relates to a rust stable surface treatment method for a steel material, which does not involve a stable rust forming process and loss of aesthetic appearance after the formation.

[0002]

2. Description of the Related Art Steel materials used for bridges, steel towers, buildings, marine structures, etc., as they are, cause red rust, yellow-brown floating rust, flow rust due to corrosion, and not only impair the scenery, but also cause the wall thickness due to corrosion. Since the decrease causes the strength of the structure to decrease, some anticorrosion measures are required. Conventionally, as a method of preventing corrosion of these structures, painting methods are generally used, and heavy-duty anti-corrosion coatings with long-term durability are also known.However, the coating cost is high, the service life is limited, and regular repainting is required. However, there is a problem that the maintenance cost is high because of the necessity.

On the other hand, by adding a small amount of an element such as P, Cu, Cr, or Ni to steel, rust (stable rust) having a protective property against corrosion is formed in the air in several years. Weather-resistant steel is known as a steel material having an extremely low corrosion rate. Weather-resistant steel is a so-called maintenance-free steel that has a permanent corrosion protection effect without painting after stable rust formation.
In recent years, it has been increasingly used for structures such as bridges and steel towers.

However, since it takes several years for stable rust to be formed, floating rust such as red rust and yellow rust and flowing rust occur during that period, which is not only unfavorable in appearance, but also unfavorable in the surrounding environment. May cause contamination. Further, there is a problem that stable rust is hardly formed in a sea salt particle flying environment and a snow melting salt spraying area in a coastal area, so that an available area is limited.

To solve these problems, for example, Japanese Patent Publication No. 56-33991 discloses a resin layer containing a stable rust component as a lower layer and a resin layer having excellent weather resistance and corrosion resistance as an upper layer. A surface treatment method by two-layer coating is disclosed.

Further, Japanese Patent Publication No. 53-22530 discloses a method for forming stable rust without flowing rust by applying a resin film containing a stable rust forming component. Further, Japanese Patent No. 2,666,673 discloses a steel material coated with an organic resin having a stable rust formation promoting action.

[0007]

However, among the above-mentioned prior arts, the method disclosed in Japanese Patent Publication No. 56-33991 is capable of preventing flow rust, but has a high anticorrosion property, so that the rust generation speed is low and the stability is low. There is a problem that it takes time to form rust. The method disclosed in Japanese Patent Publication No. 53-22530 has a problem in that flow rust is not sufficiently prevented in a highly corrosive environment, particularly in an environment where salt comes in. Patent 26
No. 66673 also has a disadvantage that the ability to form stable rust is inferior in a highly corrosive environment, particularly in an environment where salt comes in. In addition, these publications do not solve the problem of poor appearance such as cracking or peeling of the coating due to deterioration of the resin coating in the process of forming stable rust.

The present invention has been made in order to solve the above-mentioned problems. In particular, even in a highly corrosive environment, the surface of weather-resistant steel, ordinary steel, or the like or the surface of the rust layer thereof has red rust or the like. The present invention provides a rust-stabilizing surface treatment method for steel materials that forms stable rust early without causing floating rust or flowing rust, and does not impair the appearance of the stable rust during and after the formation process. .

[0009]

Means for Solving the Problems (1) The present invention relates to a method for forming Cu, Ni, Cr,
At least one selected from compounds of Al, Mo, and P containing 0.02 to 20% by weight in terms of metal;
Is adjusted to 1-6 by a dry film thickness of 0.01 μm.
After forming a film by coating or m, further upper layer C1 of the film ^- applying an ion and / or an organic resin paint containing the compound to form a sparingly soluble salt in a dry film thickness of 1-100μm A rust stabilizing surface treatment method for steel materials, characterized by the following.

(2) On the surface of a steel material or the surface of a rust layer of a steel material, as a lower layer, one of molybdic acid or molybdate is used.
At least 0.01% by weight of a phosphoric acid or a phosphate or polyphosphate in an amount of 0.01 to 10% by weight in terms of Mo;
After applying a treating agent containing -10% by weight and adjusting the pH to 1-6 to a dry film thickness of 0.01 μm or more to form a film, an organic resin and Cl ⁻ are further formed on the upper layer of the film. Rust stabilizing surface treatment of steel, characterized by applying an organic resin coating containing an ion forming a hardly soluble salt and / or a compound thereof in a dry film thickness of 1-100 μm.

(3) Cu, N is further added to the lower layer treating agent.
The rust stabilizing surface treatment method for steel according to (2), wherein at least one selected from compounds of i, Cr and Al is contained in an amount of 0.05 to 10% by weight in terms of metal.

[0012] (4) wherein the Cl ^- and ions and / or compounds thereof to form a sparingly soluble salt, characterized in that an ion and / or a compound of Ag (1) to (3)
The rust stabilizing surface treatment method for a steel material according to any one of the above.

(5) The steel material is P: 0.
03 to 0.15%, Ni: 0.4 to 4%, Mo: 0.1
１．５1.5%, S: 0.02% or less, Cr:
The rust stabilizing surface treatment method for a steel material according to any one of (1) to (4), which is limited to 0.1% or less.

[0014]

Embodiments of the present invention will be described below in detail. (Applicable Steel Materials) In the present invention, applicable steel materials are not particularly limited. Although the effect is also observed for ordinary steel, it is particularly effective for low alloy steel such as weathering steel containing a small amount of elements such as P, Ni, and Mo. The treated surface is preferably in a state where the scale and rust on the surface have been removed by blasting or the like, but this is not always necessary, and the effect can be seen even if the surface of the rust layer is treated.

The reason for adding the components and the reason for limiting the range of addition of the weather-resistant steel suitable as the steel material of the present invention will be described below. P: P is an important element in the present invention, and has an effect of promoting the formation of stable rust and further improving the corrosion resistance of steel after the formation of stable rust. Therefore, the necessary amount is added. If the addition is less than 0.03%, there is no effect on the improvement of the corrosion resistance, and if the addition exceeds 0.15%, the weldability deteriorates. Therefore, the addition is made 0.03 to 0.15%.

S: Since S is an element harmful to corrosion resistance,
0.02% or less. Cr: Cr has an effect of inhibiting the formation of stable rust and promoting perforated corrosion in an environment with a large amount of salt. Therefore, 0.1% or less is added.

Ni: Ni is an essential element in the present invention, and promotes the formation of stable rust even in an environment with a large amount of salt by coexistence with Mo, and further improves the corrosion resistance of steel after the formation of stable rust. effective. Addition of less than 0.4% has no effect, but addition of more than 4% is disadvantageous in terms of economy, and also tends to cause a bainite structure and deteriorate mechanical properties, particularly toughness. 0.4 ~
4%.

Mo: Mo is an essential element in the present invention, and promotes the formation of stable rust even in a salty environment by coexistence with Ni, and further improves the corrosion resistance of steel after the formation of stable rust. Has the effect of causing Addition of less than 0.1% has no effect, but addition of more than 1.5% is disadvantageous in terms of economy, and tends to form a bainite structure, deteriorating mechanical properties, particularly toughness. So, 0.
1% to 1.5%.

Specific steel materials are exemplified by P, Ni, M
The contents of o, S, and Cr are limited to the above-mentioned ranges. In addition, C: 0.15% or less, Si: 0.7% or less, Mn: 0.2% to 1.5%, Al : 0.01-0.
1%, Cu: 0.2 to 0.4%, and if necessary, Ca: 20 to 100 ppm, Ti: 0.005% to
0.1%, V: 0.005 to 0.1%, Nb: 0.00
A steel material containing one or more selected from 5 to 0.1% and B: 0.0003 to 0.001%, with the balance being Fe and unavoidable impurities. In this steel material, the reason for adding each additive element and the reason for limiting the range of addition are as follows.

C: C is added to secure a predetermined strength, but if it exceeds 0.15%, the weldability and toughness deteriorate, so the upper limit is made 0.15%.

Si: Si is added as a deoxidizing agent and a strength improving element at the time of steel making, but if added excessively, the toughness is remarkably reduced.

Mn: Mn is added in an amount of 0.2% or more to secure a predetermined strength. However, if added in excess, a bainite structure is likely to occur, and mechanical properties, particularly toughness, are degraded.

Al: Al is used as a deoxidizing agent in steelmaking at 0.0
Although 1% or more is added, if it is added excessively, inclusions that become corrosion starting points are easily generated.

Cu: Cu has an effect of maintaining rust in a stable state after stable rust is formed.
% Or more. Addition exceeding 0.4% saturates the effect and is disadvantageous in terms of economy, so it is set to 0.4% or less. (Treatment agent 1) (1) There are two types of treatment agents applied to the surface of the steel material or the surface of the rust layer of the steel material. The first treatment agent (lower layer) applied first to the surface of the steel material or the surface of the rust layer of the steel is Cu. , Ni, Cr,
The second treatment agent (upper layer) contains compounds of Al, Mo, and P, and ions forming a sparingly soluble salt with chloride ions and / or
Or a resin containing a chelate-forming group containing the compound.

First treatment agent (lower layer) (Cu, Ni, C
r, Al, Mo, P) In the present invention, the first treating agent contains at least one compound of Cu, Ni, Cr, Al, Mo, and P in an amount of 0.02 to 20% by weight in terms of metal. Then, the treating agent whose pH was adjusted to 1 to 6 was dried at a dry film thickness of 0.0
A lower layer is formed by coating at least 1 μm. This promotes stable rust formation. This is presumably because these ions have an effect of transforming iron ions into stable rust and a fine effect of stable rust particles. When their content is less than 0.02% by weight, the effect of promoting the formation of a stable rust layer becomes insufficient, and the effect remains unchanged even if it exceeds 20% by weight.

The pH of the treating agent is adjusted to 1 to 6. pH
If the pH exceeds 6, the effect of promoting stable rust is not sufficient, and if the pH is less than 1, the surface of the steel material or the surface of the rust layer of the steel material is excessively dissolved to form a stable rust layer. What is used for adjusting the pH can be used without any particular limitation as long as it is other than one that may generate chloride ions.For example, sulfuric acid, nitric acid, inorganic acids such as phosphoric acid are preferably used. Can be Sodium hydroxide, potassium hydroxide,
There is no problem if alkali such as sodium carbonate and ammonia coexist for pH adjustment. These metal ions or compounds may be supplied in any form as long as they do not form an insoluble salt and do not contain chloride ions that inhibit stable rust formation.

Second Treatment Agent (Upper Layer) (Resin Having Chelate-Forming Group) The resin having a chelate-forming group according to the present invention can be used to fix and concentrate steel-eluting ions at the interface to form a uniform stable rust layer. Presumed. Also C
By adding u, Ni, Cr, Al, Mo, and P, the generation rate of the stable rust layer is increased. The organic resin containing a chelating group may be either a resin component having a chelating group in the basic skeleton of the resin or a resin component containing a chelating agent alone. Suitable chelating groups are selected from amino acid groups, carboxyl groups, dithiocarbamic acid groups, polyamino groups, thiol groups, thioureido groups, dithioic acid groups, β-diketone groups, hydroxamic oxime groups, and salts thereof. At least one kind or two or more kinds.

As specific examples, the resin component having a chelating group in the basic skeleton of the resin includes an iminodiacetic acid group, an amino acid group, an oxime group, an amidoxime group, an oxine group, a glucamine group, an aminophosphate group, and a dithiocarbamic acid group. Thiourea group, β-diketone, polyamine, cryptand, crown ether, etc., capable of forming a chelate alone and a skeleton, and a Schiff base and a hydroxyl group, an azo bond and a hydroxyl group, an azo bond and a carboxylic acid, an azo bond and a carboxylic acid, an amine and phosphoric acid,
Amine and thiocarboxylic acid, amine and thiocarbonyl group,
A site capable of forming a chelate by a plurality of functional groups such as a carbonyl group and a hydroxyl group is a styrene-divinylbenzene copolymer, an acrylonitrile-divinylbenzene copolymer, an ethyleneimine polycondensate, a phenol resin, an epoxy resin, a butyral resin, A resin component introduced into a base resin such as a vinyl resin, a urethane resin, a polyester resin, an acrylic resin, and an alkyd resin. Further, a low molecular compound having the above chelating group, that is, a chelating agent may be used in a form mixed with an organic resin.

The proportion of the organic resin component having a chelate-forming group added to the treating agent is preferably 2 to 50% by weight. If it is less than this range, the effect of preventing flow rust is inferior, and if it exceeds this range, the effect does not change.

(Sparingly Soluble Salt) The treating agent of the present invention contains ions and / or compounds which form a sparingly soluble salt with chloride ions. The treated film formed by applying the treating agent of the present invention plays a role in preventing the generation of flowing rust until a stable rust layer is formed. At this time, ions and / or compounds that form a sparingly soluble salt with chlorine ions contained in the organic resin film cause the chlorine ion to enter the organic resin film from the outside, particularly in an environment where sea salt particles fly, so that the poorly soluble salt Is formed, and as a result, permeation of chlorine ions to the steel surface can be prevented. The ion or compound that forms a sparingly soluble salt with chloride ion is not particularly limited as long as it forms a sparingly soluble salt with chloride ion, but silver ion is particularly preferred, and silver nitrate (AgNO ₃ ) Is preferably a component of an organic resin paint. Silver also has an effect as an antibacterial agent, prevents adhesion of microorganisms and the like to the coating film, and is preferable in terms of the appearance of the coating film. The content of the ion or compound is preferably 0.03% by weight or more and 20% by weight or less in terms of metal.

(Pigment, Paint Conditioning Agent) In addition to the above components, it is preferable to add other organic resin components, various pigments, coating conditioners and the like to the treating agent of the present invention. The organic resin component is not particularly limited, but a resin capable of forming a coating film at room temperature is preferable, and specifically, a butyral resin,
Epoxy resin, vinyl resin, urethane resin, polyester resin, acrylic resin, alkyd resin and the like can be applied.
Resins that require effects, molding, fusion, and the like by heating are not preferred in terms of construction.

Examples of various pigments and paint modifiers include dispersants for suppressing sedimentation and separation of solids, thickeners for preventing sagging of coated surfaces, inorganic pigments such as redwood, talc and silica, condensed polycyclics, phthalocyanines An organic pigment such as a system can be appropriately added.

When the resin is formed into a coating, not only an organic solvent but also a water-based coating such as a water-soluble coating or an emulsion coating may be used as a solvent. The dry film thickness of the treated film is 1 to 100 μm. If it is less than this range, the effect of preventing chloride ions and flow rust is inferior, and if it exceeds this range,
The protective effect on the underlying steel material becomes excessive, and it takes time to form stable rust.

By forming an upper layer film having a chelate-forming group on the lower layer film in a dry film thickness of 1 to 100 μm, flow rust and floating rust can be prevented even in a severe corrosive environment such as a sea salt particle flying environment. It hardly occurs and exhibits an extremely excellent effect in appearance. This is presumed that the resin having a chelate-forming group according to the present invention fixes and concentrates the steel-eluting ions at the interface to form a uniform stable rust layer. In particular, pH
Treatment agents adjusted to 1 to 6 (Cu, Ni, Cr, Al, M
A stable rust layer is formed by the lower layer coated with (o, P). In the formation process, the steel-eluting ions are chelated and fixed to prevent outflow (flowing rust) from the coating film surface. Promotes stable rust formation. In particular, ions that form a sparingly soluble salt with chlorine ions trap foreign chlorine ions, which are factors inhibiting the formation of a stable rust layer, and can stably form stable rust.

(Treatment method) In the treatment method of the present invention, treatment can be carried out by a known coating method, that is, air spray, airless spray, brush coating, or the like, and the treatment method is not particularly limited. In addition, since processing such as heating and baking is not particularly required, both factory construction and on-site construction are possible.

(Treatment film 2) (2) There are two types of treatment agents applied to the surface of the steel material or the surface of the rust layer of the steel material. The first treatment agent (lower layer) applied first to the surface of the steel material or the surface of the rust layer of the steel material Contains molybdic acid, molybdate, and phosphoric acid, phosphate, and polyphosphate. The second treatment agent (upper layer) includes a resin having a chelate-forming group containing ions and / or a compound that forms a sparingly soluble salt with chloride ions, and Cu,
An organic resin paint containing a compound of Ni, Cr, and Al.

First Treatment Agent (Lower Layer) Addition of one or more of molybdic acid or molybdate and one or more of phosphoric acid or phosphate or polyphosphate contributes to uniform stable rust formation. By adding these, stable rust with a remarkably small number of defects is expected to be formed at an early stage, which is an unexpected effect. The solution promotes the corrosion of steel and elutes iron ions, but due to the presence of molybdate and phosphate ions,
It is presumed that iron ions are fixed and the formation of fine and uniform stable rust is promoted.

One or more of molybdic acid or molybdate is 0.01 to 10% by weight in terms of Mo, and one or more of phosphoric acid or phosphate or polyphosphate is 0.01 to 10% by weight in terms of P.
Contains 10% by weight. If the Mo content is less than 0.01% by weight, the formation of stable rust is not promoted, and the effect does not change even if the Mo content exceeds 10% by weight. The supply form of molybdenum is not particularly limited as long as it is soluble in a solution having a pH in the range of 1 to 6. For example, sodium molybdate,
Potassium molybdate, molybdophosphate and the like can be mentioned.

When the P content is less than 0.01% by weight,
The formation of stable rust is insufficient, and the effect does not change even if it is added in excess of 10% by weight. As a supply form of P, polyphosphoric acid such as orthophosphoric acid, metaphosphoric acid, or pyrophosphoric acid, and salts or phosphates thereof are used.
This treatment agent is applied to form a lower layer having a dry thickness of 0.01 μm. The reason for the limitation of the pH of the first treatment agent and the limitation of the film thickness of the lower layer are as follows: “The first treatment agent (lower layer) is made of Cu, Ni, C
a resin containing a compound of r, Al, Mo, and P, wherein the second treating agent (upper layer) has a chelate-forming group,
This is the same as in the case of "organic resin paint comprising a paint conditioner", and a description thereof will be omitted.

In the present invention, one or more of Cu, Ni, Cr and Al ions or compounds may be used as the treatment agent for forming the lower layer in an amount of 0.05 to 10% by weight in terms of metal.
By containing it, the effect of promoting stable rust generation is further improved.
This is presumably because these ions have an effect of transforming iron ions into stable rust and a fine effect of stable rust particles. If their content is less than 0.05% by weight, the effect of promoting formation of a stable rust layer becomes insufficient and
Even if it is added in excess of 0% by weight, the effect remains unchanged.
These metal ions or compounds may be supplied in any form as long as they do not form an insoluble salt and do not contain chloride ions that inhibit stable rust formation.

Second treating agent (upper layer) This treating agent contains a resin having a chelate-forming group,
The balance consists of pigment and paint conditioner. Regarding these points, the above-mentioned “first processing agent (lower layer) is made of Cu, Ni, C
Organic resin paint containing a compound containing a compound of r, Al, Mo, and P, and a second processing agent (upper layer) containing a resin having a chelate-forming group containing ions and / or compounds forming a sparingly soluble salt with chloride ions. , The description is omitted here.

(Film Thickness of Treated Film) The dry film thickness of the treated film is 1 to 100 μm. If it is less than this range, the effect of preventing chlorine ions and flowing rust is inferior. If it exceeds this range, the protective effect on the underlying steel material becomes excessive, and it takes time to form stable rust.

The treated film of the present invention has a dry film thickness of 1 to 10
By coating at 0 μm, flowing rust and floating rust hardly occur even in a severe corrosive environment such as an environment in which sea salt particles fly, and an extremely excellent appearance effect is exhibited. This is presumed that the resin having a chelate-forming group according to the present invention fixes and concentrates the steel-eluting ions at the interface to form a uniform stable rust layer. In particular, molybdic acid (salt) and (poly) phosphoric acid (salt)
A dramatic effect is exhibited in combination with. And Cu, N
By adding i, Cr, and Al and adjusting the pH to 1 to 6,
Improves the formation rate of stable rust layer. In particular, ions that form a sparingly soluble salt with chlorine ions trap foreign chlorine ions, which are factors inhibiting the formation of a stable rust layer, and can stably form stable rust.

[0044]

Next, the present invention will be described based on embodiments. Table 1 shows the chemical components of the test steels used in the examples of the present invention.
In Table 1, A indicates ordinary steel, and B indicates weather-resistant steel. Table 2 shows the base resin which is a main component of the organic resin paint.

The test steel material is 150 mm × 70 m.
It is mx 6 mm and the surface is blasted. Tables 3-1 to 3-4 show preparation conditions and test results of each test piece.

The treating agent was applied by brush, and the organic resin coating was applied by airless spray. This test piece was exposed for one year at an exposure test site in Tsu City, Mie Prefecture. The exposure site is about 200m from the coast.

After exposure for one year, the presence or absence of flowing rust and the state of the coating were confirmed by appearance observation. Further, the number of defects in the rust layer was measured by a ferroxyl test, and the amount of floating rust was measured by a tape peeling test. Tape peel test is 5
Using a tape of 0 mm × 50 mm, the same amount of the peeled floating rust was repeated three times at the same position of the test piece. Further, the remaining treated film and rust were removed by using caustic soda, and the decrease in corrosion weight was measured. It should be noted that the ferro-hexyl test results, less than the color number 100 / dm ² as "○", the 100 / dm ² or more and less than 200 cells / dm ² "△", "×" the 200 / dm ² or more, As a result of the tape peeling test, “○” indicates less than 0.01 g, “△” indicates 0.01 g or more and less than 0.05 g, and “×” indicates 0.05 g or more.

In the examples of the present invention, despite the exposure to severe corrosive environments near the coast, the ferroxyl test showed that the rust layer had few defects and had little corrosion loss.
In addition, from the result of the tape peeling test, almost no floating rust was observed, so that it was confirmed that stable rust was being formed under the coating, and there was no generation of flowing rust, cracking of the coating, peeling, etc., and it was extremely good. Appearance. In particular, Mo, P
It has been confirmed that the addition of both (corresponding to the invention of claim 2) has particularly excellent effects.

In the treatment method of the present invention, it is confirmed that the effect applied to the weather-resistant steel (No. 17) is high, but that the ordinary steel (No. 1-16) has a sufficient effect. Was. On the other hand, as shown in the comparative examples, those having a dry film thickness that is too thin and deviate from the present invention (No. 18) have flowing rust, a large amount of corrosion loss,
The results of the ferroxyl test and the tape test are not good. Those that are too thick and out of the scope of the present invention (No. 1
9) The results of ferroxil test and tape test are not good. In addition, those in which Cu, Ni, Cr, Al, etc. were not added (No. 20), and those in which the addition amount was small, but out of the scope of the present invention (No. 21 and No. 22)
) Had run-off rust, a large amount of corrosion loss, and poor results in the ferroxyl test and the tape test. Those containing no AgNO ₃ in the organic resin film (Nos. 23 and 24) show run-through rust, a large amount of corrosion loss, and the results of the ferroxyl test and the tape test are not good.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

According to the present invention, stable rust can be formed on the surface of weather-resistant steel, ordinary steel, etc. or on the surface of its rust layer without causing floating rust such as red rust or flowing rust even in a highly corrosive environment. It is possible to provide a method for accelerating the formation of weather-resistant stable rust, which is formed early and does not impair the appearance during and after the stable rust formation process.

Continuing from the front page (72) Inventor Akihiko Furuta 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kenichi Tanaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Inside the corporation

Claims (5)

[Claims] Claims: 1. On the surface of a steel material or the surface of a rust layer of a steel material,
Drying a treating agent containing at least one selected from the compounds of Cu, Ni, Cr, Al, Mo, and P in an amount of 0.02-20% by weight in terms of metal and adjusting the pH to 1-6. After applying a film with a thickness of 0.01 μm or more to form a film,
Furthermore upper layer C1 of the film ^- the the ion and / or an organic resin paint containing the compound to form a sparingly soluble salt 1-
A rust-stabilizing surface treatment method for steel materials, which is applied with a dry film thickness of 100 μm. 2. The method according to claim 1, wherein the surface of the steel material or the surface of the rust layer of the steel material is
As a lower layer, one or more of molybdic acid or molybdate is 0.01-10% by weight in terms of Mo, and one or more of phosphoric acid or phosphate or polyphosphate is 0.01-10% in terms of P.
After forming a film by coating 0.01μm or more treating agent comprising the pH was adjusted to 1-6 contains% by weight on a dry film thickness, and further the organic resin in the upper layer of the coating, Cl ^- and flame A rust-stabilizing surface treatment method for steel, comprising applying an organic resin coating containing ions forming a soluble salt and / or a compound thereof in a dry film thickness of 1 to 100 μm. 3. The underlayer treating agent further comprises Cu, Ni, C
3. The rust stabilizing surface treatment method for steel according to claim 2, wherein at least one selected from r and Al compounds is contained in an amount of 0.05 to 10% by weight in terms of metal. 4. The steel material according to claim 1, wherein the ion forming a poorly soluble salt with Cl ⁻ and / or a compound thereof is an Ag ion and / or a compound thereof. Rust stabilizing surface treatment method. 5. The steel material has a P content of 0.03% by weight.
0.15%, Ni: 0.4-4%, Mo: 0.1-1.
5%, S: 0.02% or less, Cr: 0.1
%. The rust stabilizing surface treatment method for steel materials according to claim 1, wherein the rust stabilizing surface treatment method is limited to not more than%.