JPH11244779A - Rust stabilized surface treated steel - Google Patents

Abstract

(57) [Abstract] [Problem] To provide stable rust at an early stage without generating floating rust such as red rust or flowing rust on the surface of weather-resistant steel or ordinary steel or the surface of its rust layer even in a highly corrosive environment. Provided is a rust-stabilized surface-treated steel material which is formed and does not impair its appearance during and after a stable rust formation process. SOLUTION: Cu, Ni, Cr, Al,
Mo, and 0.03-15% by weight in terms of metal of at least one or more selected from compounds of P, Cl ^- and the ions and / or compounds forming sparingly soluble salts, and the organic resin, a pigment, paint 1-10
A rust-stabilized surface-treated steel material formed with a thickness of 0 μm.

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 formation of stable rust on 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, the weather-resistant stable rust layer having an anticorrosive protective action on the surface of the steel is promptly promoted and generated, The present invention relates to a rust-stabilized surface-treated steel material that does not involve a stable rust formation 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. The weather-resistant steel is a so-called maintenance-free steel that has a permanent anticorrosion effect without being painted after stable rust is formed. 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. It is intended to provide a rust-stabilized surface-treated steel material which forms stable rust at an early stage 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) In the present invention, at least one selected from the group consisting of compounds of Cu, Ni, Cr, Al, Mo, and P is coated on a steel material surface in an amount of 0.0
3-15 and wt%, Cl ^- and forming the ions and / or compounds forming sparingly soluble salts, and the organic resin, a pigment, a conversion coating comprising a coating preparations with a thickness of 1-100μm A rust-stabilized surface-treated steel material characterized by being made.

(2) On the surface of the steel material, at least one of molybdic acid or molybdate is 0.02-7% by weight in terms of Mo, and at least one of phosphoric acid or phosphate and polyphosphate is P. and 0.02-7 wt% in terms of, Cl ^- and 1-100μm and ions and / or compounds forming sparingly soluble salts, and the organic resin, a pigment, a conversion coating containing a coating preparations
A rust-stabilized surface-treated steel material characterized by being formed with a film thickness of:

(3) Cu, Ni,
(2) The rust-stabilized surface-treated steel material according to (2), containing at least one selected from compounds of Cr and Al in an amount of 0.07-7% by weight in terms of metal.

(4) The rust-stabilizing surface treatment according to any one of (1) to (3), wherein the substance that forms the Cl ^- poorly soluble salt is Ag ion and / or a compound thereof. Steel.

(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-stabilized surface-treated 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, reasons for adding each element or element and reasons 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 film 1) (1) The treatment film applied and formed on the surface of the steel material or the surface of the rust layer of the steel material includes an organic resin, an ion and / or a compound which forms a sparingly soluble salt with chlorine ions, Cu, Ni, C
It contains compounds of r, Al, Mo, and P, a pigment, and a paint conditioner.

(Organic Resin) The organic resin according to the present invention is not particularly specified. In particular, a resin having a chelate forming group fixes and concentrates steel-eluting ions at the interface to form a uniform stable rust layer. It is preferable because it is formed. 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 chelate-forming 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 added to the treated film is preferably 3 to 75% 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.

(Compound of Cu, Ni, Cr, Al, Mo, P) In the present invention, Cu,
One or more compounds of Ni, Cr, Al, Mo and P are contained in an amount of 0.03 to 15% by weight in terms of metal. With this,
The effect of promoting stable rust generation is further improved. This is presumably because they have an effect of transforming iron ions into stable rust and a fine effect of stable rust particles. If their content is less than 0.03% by weight, the effect of promoting the formation of a stable rust layer will be insufficient, and the effect will not be changed even if it exceeds 15% by weight. 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.

(Sparingly Soluble Salt) The treated film of the present invention contains ions and / or compounds which form a sparingly soluble salt with chlorine ions. The treated film 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 antibacterial effect,
Microorganisms and the like are prevented from adhering to the coating film, which is also preferable from the viewpoint of the coating film appearance. The ion or compound has a metal content of 0.1.
It is preferably from 03% by weight to 20% by weight.

(Pigment, paint conditioner) In addition to the above components, it is preferable to add other organic resin components, various pigments, paint conditioners and the like to the treated film of the present invention. The organic resin component is not particularly limited, but is preferably a resin capable of forming a coating film at room temperature, specifically, butyral resin, epoxy resin, vinyl resin, urethane resin, polyester resin, acrylic resin, and alkyd resin. Etc. 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 / separation of solids, thickeners for preventing sagging of coated surfaces, inorganic pigments such as red iron oxide, talc and silica, condensed polycyclic, phthalocyanine 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. (Film thickness of treated film) The dry film thickness of the treated film is 1-1.
The thickness is preferably set to 00 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
When the organic resin fixes and concentrates steel-eluting ions at the interface to form a uniform stable rust layer by coating and forming 0 μm, Cu, Ni, Cr, Al, Mo, P compounds and p
H1-6 enhances the generation rate of stable rust. further,
Ions and compounds that form poorly soluble salts with chloride ions trap foreign chloride ions, which are factors that inhibit stable rust formation. As a result, flowing rust and floating rust hardly occur even in a severe corrosive environment such as a sea salt particle flying environment, and an extremely excellent effect is exhibited in appearance.

(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) The treatment film applied and formed on the surface of the steel material or the surface of the rust layer of the steel material is molybdic acid, molybdate, phosphoric acid, phosphate, polyphosphate, chlorine ion, and chlorine ion. It contains ions and / or compounds forming a soluble salt, an organic resin, and, if necessary, compounds of Cu, Ni, Cr, and Al, a pigment, and a paint conditioner.

(One or more molybdic acid or molybdate and one or more phosphoric acid or phosphate or polyphosphate)
The 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, it is quite unexpected that stable rust with a remarkably small number of defects is formed at an early stage.However, such an effect is obtained by first using a predetermined acidic solution. Thus, corrosion of the steel material is promoted and iron ions are eluted, but it is presumed that the presence of molybdate and phosphate ions fixes the iron ions and promotes the formation of fine and uniform stable rust.

One or more of molybdic acid or molybdate is 0.02 to 7% by weight in terms of Mo, and one or more of phosphoric acid or phosphate and polyphosphate is 0.02 to 7% in terms of P.
% By weight. If the Mo content is less than 0.02% by weight, the formation of stable rust is not promoted, and even if added over 7% by weight, the effect remains unchanged. 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, and examples thereof include sodium molybdate, potassium molybdate, and molybdophosphate.

When the P content is less than 0.02% by weight,
The formation of stable rust is insufficient, and the effect does not change even if added over 7% 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.

Further, the treated film contains an organic resin as a solid content, preferably 3 to 75%, and contains ions and compounds which form a sparingly soluble salt with chloride ions, a pigment and a paint conditioner, The preferred pH is between 1 and 6. Regarding these points, as described above, “an organic resin, an ion and / or a compound that forms a sparingly soluble salt with chloride ion, an ion and a compound that forms a sparingly soluble salt with chloride ion, Cu, Ni,
It is the same as the “treated film containing a compound of Cr, Al, Mo, and P, and a pigment and a paint conditioner”, and the description of the same components is omitted here.

(Compound of Cu, Ni, Cr, Al) In the present invention, Cu, Ni, C
at least one compound of r and Al in an amount of 0.07 to
By containing 7% by weight, 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. When their content is less than 0.07% by weight, the effect of promoting the formation of a stable rust layer becomes insufficient, and the effect does not change even if added over 7% by weight. The supply form of these metal ions or compounds is
Any form may be used as long as it does not form an insoluble salt and does not contain chloride ions that inhibit stable rust formation.

(Thickness of Treated Film) The dry film thickness of the treated film is preferably 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 is dried at a film thickness of 1 to 10
By applying 0 μm, when the organic resin fixes and concentrates the steel-eluting ions at the interface to form a uniform stable rust layer,
The combination of molybdate and polyphosphate has a dramatic effect, and the ions and compounds that form salts and ions and sparingly soluble salts can reduce foreign chlorine ions that are a factor inhibiting stable rust formation. Trap and stabilize stable rust formation. Further, the addition of Cu, Ni, Cr, and Al and the pH of 1-6 increase the production rate of stable rust. For this reason, even in a severe corrosive environment such as an environment where sea salt particles fly, almost no flow rust or floating rust is generated, and an extremely excellent appearance is exhibited.

[0042]

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 was 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 treatment 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 observation of the appearance. 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 embodiments of the present invention, despite the exposure to severe corrosive environments near the coast, the ferroxyl test shows that the rust layer has few defects and 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 was confirmed that the effect applied to the weather-resistant steel (No. 19) was high, but that the ordinary steel (No. 1-18) had a sufficient effect. Was. On the other hand, as shown in the comparative examples, those having a dry film thickness which is too thin and out of the range of the present invention (No. 20) have flow rust, a large amount of corrosion loss, and the results of the ferroxyl test and the tape test are also high. Not good. Those that are too thick and out of the scope of the invention (N
o) For 21), the results of the ferroxyl test and tape test are not good. In addition, those in which Cu, Ni, Cr, Al, etc. were not added (No. 22), and those in which the addition amount was small, but out of the scope of the present invention (No. 23, N
o.24) had run-off rust, a large amount of corrosion loss, and poor results in the ferroxyl test and tape test. The organic resin film containing no AgNO ₃ (Nos. 25 and 26) shows run-off rust, a large amount of corrosion loss, ferroxil test,
The results of the tape test are not good either.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

[0054]

The treated film of the present invention has a dry film thickness of 1 to 1
By coating with a thickness of 00 μm, even in a severe corrosive environment such as an environment in which sea salt particles fly, almost no flowing rust or floating rust is generated, and an extremely excellent appearance is exhibited.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Miyata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Masahito Kaneko 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Honko Co., Ltd.

Claims (5)

[Claims] 1. A steel material having Cu, Ni, Cr, A
l, Mo, and 0.03-15 wt% of at least one or more in terms of metal selected from a compound of P, Cl ^- and the ions and / or compounds forming sparingly soluble salts, and the organic resin, a pigment , A coating film containing a paint preparation agent
A rust-stabilized surface-treated steel material formed to have a thickness of −100 μm. 2. The steel material is coated with at least one of molybdic acid or molybdate in an amount of 0.02 to 7% by weight in terms of Mo.
And at least one of phosphoric acid or phosphates and polyphosphates by P
And 0.02-7 wt% in terms of, Cl ^- and the ions and / or compounds forming sparingly soluble salts, and the organic resin, a pigment,
A rust-stabilized surface-treated steel material, wherein a treated film containing a paint preparation agent is formed in a thickness of 1 to 100 μm. 3. The treatment film further comprises Cu, Ni, Cr,
The rust-stabilized surface-treated steel material according to claim 2, wherein 0.07 to 7% by weight of at least one selected from Al compounds is calculated in terms of metal. 4. The compound which forms the Cl ^- sparingly soluble salt is A
The rust-stabilized surface-treated steel material according to any one of claims 1 to 3, wherein the ion is g and / or a compound thereof. 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-stabilized surface-treated steel material according to claim 1, wherein the steel material is limited to not more than%.