JP2002180265A - Rust prevention-treated metallic product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rust prevention-treated metallic product whose surface has a rust prevention treatment film having low environmental load properties, and imparting sufficient corrosion resistance with a thin film thickness. SOLUTION: The rust prevention-treated metallic product has a rust prevention treatment film on the surface. The film contains water based organic resin containing (A) water dispersible resin having the salt of a carboxyl group (- COO)aZb (wherein, Z is a cation having a valence c other than hydrogen ion and a cation having high environmental load properties, and, further, the number of carboxylic residues a = the number of the cations b × the valence c) and (B) water-dispersible resin having cyclic imino ether groups as pendant groups expressed by the formula (1) by 25 to 100 mass% in total, and an organic compound with a structure consisting of a noncyclic structure or a heterocyclic structure containing one or more sulfur atoms as the main skeleton, and to which one or more functional groups containing one or more kinds selected from among sulfur, nitrogen and oxygen are added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rustproof metal product having a rustproof film having excellent corrosion resistance on its surface.

[0002]

2. Description of the Related Art In order to improve the rust prevention of metal materials such as various metals, alloy materials, and various types of plated steel materials, C is often used.
A coating type chromate treatment containing r (VI) (hexavalent chromium) is performed. The passive film formed on the surface of the metal material by the chromate treatment exhibited excellent shielding properties against corrosion factors and a self-healing function against film damage, and was the most effective rust prevention technology.

[0003] However, with the growing interest in global environmental issues in recent years, harmful Cr (VI) and furthermore Cr
There is a need for a rust-proofing metal material that does not contain any (III), and Cr (VI,
III) Development of free rust prevention technology is urgently needed.
Among the inorganic compounds containing no chromium compound, those having a corrosion inhibiting function for metals have been found, and like the chromate, have been used for rust prevention treatment for a long time.

[0004] Of these, nitrites, which passivate metals like chromates, and treatment solutions based on permanganate, which have a strong oxidizing power, significantly reduce the corrosion of metal materials, but are stable. Inferior to chromate treatment in properties and efficacy (Maeda Shigeyoshi, Surface, 21, 37 (6), 1999,
Association of Corrosion and Corrosion Protection, Metal Corrosion Protection Technical Handbook (New Edition 4th Edition),
p. 551, Nikkan Kogyo Shimbun, 1977).

[0005] Vanadate, molybdate, and tungstate are oxyacid compounds similar to chromates, and passivate many metal surfaces. Far below. Also, among these inorganic compounds, nitrite, vanadate,
It is known that many substances, such as permanganate and molybdate, do not necessarily have low environmental impact, and, like chromate, the PRTR Law (enforcement of specific chemical substances to the environment) to be enforced in April 2001 It is not preferable to use it as a component of the rust treatment liquid because it may be subject to the Act on Understanding of Emissions and Promotion of Improvement of Management.

[0006] Phosphates, silicates and the like which form a stable oxide film on the metal surface are not so problematic in terms of environmental load, but do not attain the rust-preventive effect of the chromate-treated film at all. On the other hand, examples of metal (Cr, VI, III) -free rust-prevention treatment liquid or rust-prevention treatment metal products containing organic resin as a main component include silica particles, phosphonic acid derivatives in addition to water-dispersible or water-soluble resins. Surface treatment liquid containing zirconia, zinc-coated steel sheet coated with the treatment liquid (JP-A-11-36079), water dispersion having segments composed of polyhydroxyether and segments composed of a polymer of an unsaturated monomer mixture Surface treatment liquid containing conductive resin, phosphoric acid, and phosphoric acid-based metal compound, cold-rolled steel sheet, plated steel sheet (JP-A-11-50010) coated with the treatment liquid, water-dispersible or water-soluble resin, and polymer chelation Zinc-coated steel sheet and aluminum-based steel sheet coated with a surface treatment solution containing
No. 000-519), an aqueous resin, a sulfide ion, or a surface treatment solution for uncoated steel and zinc-coated steel containing a sparingly soluble sulfide or phosphate ion (JP-A-8-67834).
Has recently been disclosed.

[0007] These treatment liquids (or anti-rust treated steel sheets)
Is chromate treated (or
Water-based organic resin, which is the main component of the treatment liquid, does not contain the compounds subject to the PRTR method. It does not use an organic solvent when applying the treatment liquid.
Since it is r (VI, III) free, it is useful for reducing environmental load.

However, aqueous organic resins are expensive in comparison with many inorganic compounds due to the time required for their synthesis.
In addition, in order for a rust-preventive film containing an organic resin as a main component to exhibit sufficient corrosion resistance on a metal surface, the rust-preventive film needs to be thicker than most inorganic rust-preventive films. (Molybdate, molybdate, tungstate) and nitrites, which require several times to ten times or more film thickness compared to inorganic compounds that passivate the metal surface densely, resulting in enormous film cost. There were drawbacks.

When a suitable reaction condition is selected in a coexistence system of a resin containing an active hydrogen-containing electrophilic group such as a carboxyl group or a carboxylic anhydride group and a resin containing a cyclic imino ether group, the electrophilic group is obtained. A cyclic imino ether group reacts with a cyclic imino ether group, an acid anhydride group or the like, a covalent bond is generated through ring opening of the cyclic imino ether group, and a resin composite is formed by crosslinking. Utilizing such a reaction, excellent storage stability, solvent resistance,
It is known to obtain a coating composition capable of forming a coating film having excellent adhesion to a coated surface and excellent hardness.

For example, an aqueous coating composition for undercoating under floors of automobiles, comprising an SBR latex having a carboxyl group, a water-dispersible acrylic resin having an oxazoline group which is one of cyclic imino ether groups, and an inorganic filler. Excellent in strong adhesiveness to an adherend, water resistance after coating film formation, chipping resistance, blister resistance, etc. (JP-A-7-207214), an acrylic resin having a carboxyl group and an oxazoline group A thermosetting coating composition for an automotive top clear coat comprising an acrylic resin having excellent acid resistance, car wash scratch resistance, air wiping scratch resistance and the like after coating (Japanese Patent Application Laid-Open No. 9-286949).
Publication), a room temperature curable aqueous coating composition containing a polymer fine particle having a carboxyl group or a specific carbonyl group in the outer shell, a polymer having an oxazoline group, and a hydrazine derivative as a cross-linking agent. Hardness, adhesion,
Excellent in water resistance, oil resistance, etc.
No. 99), a polymer having a carboxyl group, a polymer having an oxazoline group, and an aqueous dispersion of a resin composition obtained by dispersing a mixture further containing a basic compound, if necessary, in an aqueous medium. An aqueous coating composition containing a polymer having a carboxyl group and a polymer having an oxazoline group, which is excellent in solvent resistance after coating film formation, pencil hardness, etc. (JP-A-9-296122); Which have excellent properties, solvent resistance after coating film formation, and processability (Japanese Patent Application Laid-Open No. 9-328656).

[0011]

According to the present invention, many of the above-mentioned inorganic coatings have a high environmental load and are less rust-proof than a chromate coating. It is an object of the present invention to solve the problem of the prior art that is cost, and to provide a rust-preventive metal product that has low environmental load and a small amount of coating film, that is, low-cost and sufficient corrosion resistance.

[0012]

Means for Solving the Problems The present inventors have made various studies to solve the above-mentioned problems, and as a result, a cyclic imino ether group is used as a pendant group in a water-dispersible resin having a salt of a carboxyl group. Adding a water-dispersible resin having
It has been found that by dispersing an organic compound having a specific structure in a resin composition composed of these, a rust-preventive film having low environmental load and exhibiting sufficient corrosion resistance with a small film thickness can be obtained.

The present invention has been completed based on such findings, and the gist thereof is as follows. (1) Carboxyl group salt (—COO) _a Z _b (where Z is a cation having a valency of c, excluding hydrogen ions and cations having a high environmental load. In addition, the number of carboxylic acid residues a =
The number of cations is b × the valence number c. (A) having a cyclic imino ether group

[0014]

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[0015] (wherein, the number n of repeating units is 2 to 5 integer, substituents -R _A and -R _B is a hydrocarbon group having 1 to 10 hydrogen atoms or carbon atoms.) As pendant groups An aqueous organic resin containing a total of 25 to 100% by mass (based on solid content) of a water-dispersible resin (B) having a non-cyclic structure containing at least one sulfur atom as a main skeleton, and a carboxyl group -COOH containing An organic compound (a) having a structure in which one or more and one or more functional groups containing one or more of sulfur, nitrogen and oxygen are added, or containing two or more sulfur atoms The main skeleton is a heterocyclic structure or a heterocyclic structure containing at least one sulfur atom and at least one nitrogen atom, and one or more functional groups containing at least one of sulfur, nitrogen and oxygen are added to the main skeleton. Selected from organic compounds (b) having a modified structure A rust preventive metal product having a rust preventive coating containing at least one kind of organic compound on its surface.

(2) The water-dispersible resin (A) contains a carboxyl group —COOH and a carboxylic anhydride group (—CO) ₂
The rust-preventive metal product according to (1), further comprising at least one of O. (3) The total amount of the salt of the carboxyl group, the carboxyl group, and the carboxylic anhydride group of the water-dispersible resin (A) is 0.1 to 15% by mass based on the total solid content of the water-dispersible resin (A). The rust-proofing metal product according to the above (1) or (2), characterized in that:

(4) The content of the cyclic imino ether group contained in the water-dispersible resin (B) is from 1 to 25 of the total solid content of (B).
The rust-preventive metal product according to any one of (1) to (3), which is a mass%. (5) The total amount of the salt of the carboxyl group, the carboxyl group, and the carboxylic anhydride group of the water-dispersible resin (A) is
The rust preventive treatment according to any one of the above (1) to (4), wherein the amount is 0.05 to 50 equivalents relative to the content of the cyclic imino ether group contained in the water-dispersible resin (B). Metal products.

(6) The protection according to any one of (1) to (5), wherein the dispersed particle diameter of the water-dispersible resins (A) and (B) is 0.003 μm or more. Rusted metal products. (7) Organic compounds (a) and (b) have a structure in which two carboxyl groups -COOH are added to the main skeleton (1) to (1).
(6) The rust-proof metal product according to any one of (6).

(8) When the organic compound (a) is sulfide-S-, disulfide-SS- or thiol-S
The rust-preventive metal product according to (7), wherein the non-cyclic structure containing any one or two or more bonds of H is a main skeleton. (9) The organic compound (b) has, as a main skeleton, a 5-membered heterocyclic structure containing at least one sulfur atom and at least one nitrogen atom.
The rust-proofing metal product according to any one of (1) to (6).

(10) The organic compound (b) further comprises -S
The rust-preventive metal product according to (9), which has a structure in which one or more functional groups represented by H, -NH ₂ , ＳS, ＝ NH, or ＯO are added to a main skeleton. (11) The rust-preventive metal product according to any one of (1) to (10), further including a chromium compound-free pre-treatment film under the rust-preventive film. .

(12) The rust-proof metal product according to any one of (1) to (11), wherein the metal product is a steel plate. (13) The steel plate is made of zinc, aluminum, cobalt,
The rust-preventive metal product according to the above (12), wherein the surface has a plating layer made of any one of tin and nickel or an alloy containing these metal elements.

[0022]

Embodiments of the present invention will be described below in detail. In the present invention, a water-dispersible resin (A) having a salt of a carboxyl group and a water-dispersible resin (B) having a cyclic imino ether group as a pendant group are contained in an aqueous treatment liquid containing a specific structure containing a sulfur atom. Compound (a),
(B) adding at least one kind thereof to prepare a rust preventive treatment solution,
After the rust preventive solution is applied to the metal surface, the carboxyl group and cyclic imino ether group of the resin particles (A) and (B) are reacted by heating for a short time, and all or a part of the particles interact at the interface. It is a great technical point to form a rust-proofing film having a crosslinked structure and containing the organic compound. By such inter-particle crosslinking and the action of the organic compound, a water-dispersible resin (B) and a rustproofing film exhibiting sufficient corrosion resistance with a smaller film thickness (lower cost) than when the organic compound is not added are obtained. be able to.

There is no particular limitation on the metal product to which the present invention is applied. For example, aluminum, titanium, zinc, copper plate, nickel, steel and the like are applicable. Among them, when steel is used, the components are not particularly limited, and may be ordinary steel or chromium-containing steel. Further, there may be a coating plating layer on the surface of the steel, and the type thereof is not particularly limited. Examples of applicable plating layers include zinc, aluminum, cobalt, tin, and nickel plating. , And alloy plating containing these metal elements. The plating method is not particularly limited. Examples of the post-plating treatment on the steel sheet include zero spangle treatment, which is a uniform appearance treatment after hot-dip plating, annealing treatment, which is a modification treatment of a plating layer, and temper rolling for surface condition and material adjustment, and the like. In the present invention, these are not particularly limited, and any of them can be applied.

The aqueous organic resin constituting the rust preventive coating of the present invention is applied to a metal surface, and then reaches a surface temperature of 180 ° C. or less.
A water-dispersible resin (a water-insoluble resin finely dispersed in water in the form of an emulsion or suspension) or a water-soluble resin which forms a film at a drying temperature of preferably 150 ° C. or lower, and a carboxyl group salt, or And a water-dispersible resin (A) having at least one of a carboxyl group and an acid anhydride group thereof, a water-dispersible resin (B) having a cyclic imino ether group as a pendant group, and other aqueous resins (C). After heat drying and film formation, it has an excellent shielding effect of corrosion factors.

Z constituting the salt (—COO) _a Z _b of the carboxyl group of the water-dispersible resin (A) is a cation having a valence of c, and the number of carboxylic acid residues a = the number of cations b × the valence Number c
It is. The cation Z is not a hydrogen ion or an ion having a high environmental load, such as hydrogen ion and hexavalent chromium, from the gist of the present invention which does not provide a rust prevention technique having a low environmental load. As the cations having a high environmental load, the compounds containing them are Cd (II), Cr (III), and Cd (II), which are regulated as Class 1 designated chemical substances by the above-mentioned PRTR method.
Cr (VI), Ni (II), Pb (II), Sb (I
II), Sb (V), Co (II), Mn (II), S
e (IV), Be (II), Hg (I), Hg (II)
Chemical substances subject to the PRTR Law will be reviewed periodically in accordance with the status of scientific knowledge on hazards and the status of data on emissions into the environment. It should be noted that the cations of interest and the compounds containing them may increase in the future. In particular, among the above-mentioned target substances, Cd (II), Cr (VI), Ni (I), which are ranked as carcinogenic class 1 by the PRTR method as being carcinogenic to humans.
The compounds of I) and Be (II) must not only be included in the rust preventive coating of the present invention, but also must not be used in the production process of the coating.

In the private sector, Cd (II), Cr (V
For many compounds including I), Ni (II), and Be (II), use in production process and inclusion in products are prohibited.
Further, Pb (II), Sb (III), Sb (V),
A major manufacturing group has already announced that it will reduce the amount of Se (IV) and other compounds used in production processes and its content in products. Companies and new banned or reduced compounds are likely to be listed. Therefore, it is necessary to understand cations and their compounds having a high environmental load from the viewpoints of both legal regulations and private use regulations, so as not to use them in the present invention.

As the cation Z, a method such as a PRTR method is used.
Regulations that are not subject to regulations and regulations by private substance management regulations
Potassium metal ion, alkaline earth metal ion, transition metal ion
On can also be mentioned, but the total amount of the cation Z
10 equivalent% or more is an ammonium ion (NH⁴⁺),Ah
Or an aliphatic amine having a boiling point of 100 ° C. or less (for example,
Tylamine, ethylamine, n-propylamine, n-
Butylamine, dimethylamine, diethylamine, die
Sopropylamine, trimethylamine, triethylami
Ion) (CH)_ThreeNH_Three ⁺, CH_ThreeC
H_TwoNH_Three ⁺, CH_ThreeCH_TwoCH_TwoNH_Three ⁺, CH_ThreeC
H_TwoCH_TwoCH_TwoNH_Three ⁺, (CH_Three) _TwoNH_Two ⁺,
(CH_ThreeCH_Two)_TwoNH_Two ⁺, ((CH_Three)_TwoCH)_Two
NH_Two ⁺, (CH_Three)_ThreeNH⁺, (CH_ThreeCH_Two)_ThreeN
H⁺Etc.) or one or more
Preferred, especially those composed of ammonium ions
Is most preferred.

As compared with the carboxyl group, the salt of the carboxyl group is very difficult to react with the cyclic imino ether group.
Is an ammonium ion or an onium ion of a low-boiling amine, it becomes an ammonia gas or a low-boiling amine gas by heating during coating, and is volatilized and dissipated, and the crosslinking reaction between the generated carboxyl group and the cyclic imino ether group is promptly performed. move on. Ammonium ions are most preferred because they are very easily volatilized and dissipated by heating.

When the total amount of ammonium ions and the amine is less than 10% by weight of the total amount of Z, a carboxyl group is hardly generated by heating during coating, and the crosslinking reaction with the cyclic imino ether group does not proceed very much. In particular, when 90 equivalent% or more of the cation Z is a non-volatile ion such as an alkali metal ion, an alkaline earth metal ion, or a transition metal ion, the crosslinking reaction hardly proceeds. In such a case, a volatile species such as an ammonium ion is added to the water-dispersible resin (A), and a part of the non-volatile ions are replaced with the volatile ion species, thereby forming a crosslinking reaction during coating. Can be accelerated.

As a source of ammonium ions, various water-soluble ammonium salts can be used.
Preferred are those having no harmfulness or danger, such as diammonium hydrogen phosphate, ammonium dihydrogen phosphate, triammonium phosphate, ammonium hypophosphite, ammonium acetate, triammonium citrate, and ammonium tetraborate. These water-soluble ammonium salts are preferably added in the range of 0.01 equivalent to 0.3 equivalent to the salt of the carboxyl group of the water-dispersible resin (A).

In the present invention, the structure of the cyclic imino ether group contained in the water-dispersible resin (B) is represented by a general formula

[0032]

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[0033] represented by the number n of repeating units is an integer from 2 to 5, the substituents -R _A and -R _B is hydrocarbon group having 1 to 10 hydrogen atoms or carbon atoms. When n = 1, the ring becomes unstable and is not practical. When n ≧ 6, it becomes a macrocyclic pendant group, which increases steric hindrance, significantly increases the viscosity of the water-dispersible resin (B), and adversely affects the reactivity with the carboxyl group. Substituents -R _A, -R _B
When the number of carbon atoms is 11 or more, steric hindrance increases,
Not suitable for the same reasons as above. From the viewpoints of synthesis, stability and steric hindrance of the water-dispersible resin (B), 2-
Oxazoline group is preferable, and the substituents -R _A and -
More preferably, all of R _B are hydrogen atoms.

In the present invention, the total amount of the water-dispersible resins (A) and (B) is from 25 to 1 of the entire aqueous organic resin.
Aqueous resin (C) other than the water-dispersible resins (A) and (B).
Is 75 to 0% by mass, preferably 5% by mass of the entire aqueous organic resin.
0 to 0% by mass. If the total amount of the water-dispersible resins (A) and (B) is less than 25% by mass of the entire aqueous organic resin, the cross-linking density between the dispersed resin particles becomes low, so that the effect of inhibiting the transmission of the corrosion factor cannot be sufficiently obtained. .

In the present invention, the total content of the salt of the carboxyl group, the carboxyl group or the acid anhydride group thereof in the water-dispersible resin (A) is from 0.1 to the total solid content of (A).
The content of the cyclic imino ether group in the water-dispersible resin (B) is preferably 1 to 25% by mass based on the total solid content of (B). The total content of a salt of a carboxyl group, a carboxyl group or an acid anhydride group thereof is less than 0.1% by mass of the entire solid content of (A), or 1 mass% of the entire solid content of a cyclic iminoether group content of (B). %, The functional group contributing to the cross-linking reaction between (A) and (B) is so small that the cross-linking density is low, and the effect of inhibiting corrosion factor permeation may not be sufficiently obtained. On the other hand, when the total content of the salt of the carboxyl group, the carboxyl group or the acid anhydride group thereof exceeds 15% by mass of the total solid content of the resin (A), a large amount of unreacted carboxyl groups remains even after heating and drying, and Since poor water resistance and poor adhesion to metal surfaces are induced, corrosion factors can easily penetrate and come into contact with metal surfaces, resulting in insufficient corrosion resistance. The cyclic imino ether group content is 25% by mass of the total solid content of (B).
Exceeding the formula (B) is not practical because the hydrolysis resistance of (B) is lowered and the stability (pot life) of the rust preventive solution is lowered, or the production cost of (B) is increased.

The total content of the salt of the carboxyl group, the carboxyl group and the carboxylic anhydride group of the water-dispersible resin (A) is 0.1% based on the content of the cyclic imino ether group of the water-dispersible resin (B). It is preferable to set it in the range of 05 equivalents to 50 equivalents. The total content of the salt of the carboxyl group, the carboxyl group, and the carboxylic acid anhydride group of the water-dispersible resin (A) is less than 0.05 equivalent of the content of the cyclic imino ether group of the water-dispersible resin (B), Alternatively, if it exceeds 50 equivalents, a crosslinked structure between the dispersed resin particles is hardly formed, so that the effect of suppressing permeation of the corrosion factor may not be sufficiently obtained.

The relative amounts of the carboxyl group and the carboxylic anhydride group with respect to the carboxyl group salt of the water-dispersible resin (A) are not particularly limited. It is preferable that the total content of the physical groups is in the range of 0 to 4 equivalents. When the total content of the carboxyl group and the carboxylic anhydride group exceeds 4 equivalents of the salt content of the carboxyl group, the water dispersibility of the water dispersible resin (A) may be insufficient, and the resin fine particles may be dissolved in water. It may be difficult to achieve uniform dispersion.

As long as the dispersibility of the water-dispersible resin (A) in the rustproofing solution and the crosslinking reactivity during coating are not impaired,
(A) may have a functional group other than a salt of a carboxyl group, a carboxyl group, an acid anhydride group thereof, and a cyclic imino ether group (for example, a hydroxyl group, an amino group or an epoxy group). (B) is a salt of a carboxyl group, a carboxyl group, or an acid anhydride thereof, as long as the dispersibility of the water-dispersible resin (B) in the rust preventive treatment liquid and the crosslinking reactivity during coating are not impaired. And a functional group other than a cyclic imino ether group.

In the present invention, the types of the water-dispersible resin (A) and the water-dispersible resin (B) (the types of the resin constituting the skeleton of (A) and (B)) are as follows based on the functional groups of the resins. Is not particularly limited as long as it satisfies all the above conditions and has an effect of shielding corrosion factors after film formation. Examples of such a resin include a polyolefin resin, an acrylic resin, a polyurethane resin, a polycarbonate resin, a polyester resin, an epoxy resin, a phenol resin, and other heat-curable resins. In the present invention, two or more of these water-dispersible resins may be used after being mixed, modified, or copolymerized.

Further, regarding the type of the aqueous resin (C),
There is no particular limitation as long as it does not have a salt of a carboxyl group, a carboxyl group, an acid anhydride group thereof, or a cyclic imino ether group in the molecule and has an effect of shielding a corrosion factor after film formation. Such aqueous organic resins include polyolefin-based resins, polyurethane-based resins, polycarbonate-based resins, polyester-based resins, epoxy-based resins, phenol-based resins, and other heat-curable resins. It has no salt, carboxyl group, acid anhydride group, and cyclic imino ether group.

[0041]

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Such as those which are made aqueous by having a polar group having a strong hydrophilicity, those which are obtained by dispersing and emulsifying fine particles made of the above resin in water with a surfactant, or those which form an emulsion by emulsion polymerization. Can be exemplified. In the present invention, two or more of these aqueous resins may be used after being mixed, modified, or copolymerized. In the present invention, the dispersed particle diameter of the water-dispersible resin (A) and the water-dispersible resin (B) is preferably 0.003 μm or more. When a particle-dispersed treatment liquid is applied to a metal, a film is formed only by accumulating the particles. Therefore, the minimum film formation temperature (MFT) which is several degrees higher than the Tg of the resin constituting the particles is maintained, and the distance between the particles ( It is necessary to fuse the softened particles while dehydrating via a capillary. However, when the diameter of the dispersed particles is less than 0.003 μm, there is a problem particularly when the time for holding the coated surface at or above the MFT is short due to limitations in practical steps. Since the total area of the interface formed by particles having a diameter of less than 0.003 μm is very large, dehydration from a narrow space between the particles and a crosslinking reaction between the particles do not sufficiently proceed. Therefore, the effect of suppressing corrosion factor permeation is reduced.

In the present invention, the upper limit of the dispersed particle diameter of the water-dispersible resin (A) and the water-dispersible resin (B) is not particularly limited, but the particle diameter is preferably 5 μm or less. 5
If it exceeds μm, it is difficult to obtain a stable dispersion state for a long time even if a dispersant (surfactant) or the like is added, and the stability of the rust preventive solution is reduced. In addition, the particle diameter referred to here is a plot of the relationship curve between the particle size and the cumulative volume ratio,
The particle diameter d _{50 at} which the cumulative volume ratio is 50% is read.
(50% average particle size). Measuring method at that time, the solvent particles irradiated with a laser beam in a state of being dispersed in, which seek d ₅₀ and the particle size distribution by analyzing the time resulting interference fringes, as a suitable measuring device,
Examples include SALD manufactured by Shimadzu Corporation, CILAS manufactured by CILAS, and LA manufactured by HORIBA, Ltd.

In the present invention, the water-dispersible resins (A) and (B)
Incorporating at least one of the organic compounds (a) and (b) described below as a rust preventive into a continuous phase mainly composed of It is necessary to develop high corrosion resistance. Crosslinking between the particles of the water-dispersible resin (A) and (B) densifies the film and enhances the function of shielding corrosion factors. Therefore, when there is no deep crack penetrating the film formed on the surface of the metal product, high corrosion resistance is obtained. Is expressed. However, if the coating is severely damaged by bending or pressing of the product, the shielding function due to inter-particle crosslinking is not regenerated, and the metal surface may be exposed to a corrosive environment at the flaw site. In order to cope with such a case, not only the shielding coating layer is formed on the non-damaged part, but also the metal part of the damaged part is quickly moved and adsorbed, a new shielding layer is formed, and the processed part is rust-proofed. Organic compounds (inhibitors)
Is required in the coating.

The prerequisite for the organic inhibitor to exert its shielding function is that the organic compound has a high adsorptivity to the metal surface, and the adsorbed organic compound must have a sufficiently dense shielding layer to suppress the transmission of corrosion factors such as chloride ions. Is to have the ability to form From these viewpoints, the present inventors have studied various organic compounds. As a result, a non-cyclic structure containing one or more sulfur atoms was used as a main skeleton, and a carboxyl group-
An organic compound (a) having a structure in which at least one COOH and at least one functional group containing at least one of sulfur, nitrogen and oxygen are added, or at least two sulfur atoms The main skeleton is a heterocyclic structure containing a heterocyclic structure or a heterocyclic structure containing at least one sulfur atom and at least one nitrogen atom, and one functional group containing at least one of sulfur, nitrogen and oxygen is contained in the main skeleton. By dispersing at least one organic compound selected from the organic compounds (b) having the above-mentioned added structure in a continuous phase containing the water-dispersible resins (A) and (B) as main components, a small coating amount is obtained. That is, it was found that at a low cost, sufficient corrosion resistance was exhibited regardless of the presence or absence of processing.

What is common to both non-cyclic compounds and cyclic compounds is that adsorption is basically composed of one or more of sulfur, nitrogen, and oxygen atoms having a strong adsorption power to metals. There are a total of three or more sites in the compound structure. Here, in the case of a functional group including a plurality of elements having a high adsorptivity such as a —CONH ₂ group,
NH ₂ is regarded as one adsorption site. Of the three or more adsorption sites, two adsorption sites make a strong bond with the metal atom constituting the metal surface, and at the same time, the remaining adsorption sites
It is presumed that enhancing the interaction between the adsorbed compounds contributes to forming a dense structure by the adsorbed molecules on the metal surface.

In the case of a non-cyclic compound, the above-mentioned three or more adsorption sites include one or more sulfur and one or more carboxyl groups contained in the non-cyclic structure, and any one of sulfur, nitrogen and oxygen. Or one or more functional groups containing one or more of them. this is,
It is presumed that the combination with the carboxyl group and the adsorption site constituted by sulfur, which has the strongest adsorption power among sulfur, nitrogen and oxygen, causes a very strong bond to the metal surface.

Further, the constitution of one or more sulfur and two or more carboxyl groups contained in the non-cyclic structure achieves a further improvement in corrosion resistance, and furthermore, one or more carboxyl groups combined with two or more carboxyl groups Sulfide-S- and disulfide-S-S-
Alternatively, thiol-SH exhibits the most excellent corrosion resistance. In the closest combination of a sulfur atom and a carboxyl group, the number of atoms between the sulfur atom and the carbon atom constituting the carboxyl group is preferably one or more and three or less. When the sulfur atom and the carboxyl group are adjacent to each other, that is, when no atom is interposed between them, it is difficult for the sulfur atom and the carboxyl group to form a strong adsorption structure with respect to the metal atoms constituting the metal surface, while 4 atoms In the case of intervening as described above, the distance between the sulfur atom and the carboxyl group is too long, and it is difficult to form a strong adsorption structure on the metal surface.

On the other hand, in the case of a cyclic compound, a heterocyclic structure containing two or more sulfur atoms or one or more sulfur and one nitrogen atom as the three or more adsorption sites,
A structure in which one or more functional groups containing one or more of sulfur, nitrogen, and oxygen are added is necessary for developing corrosion resistance. A heterocyclic structure containing two or more sulfur atoms,
Alternatively, a heterocyclic structure containing at least one sulfur and one nitrogen atom has been found to be effective as a basic skeleton for enhancing adsorption power, and the basic skeleton of the heterocyclic structure has any one of sulfur, nitrogen, and oxygen. One or more functional groups containing one or more
It is presumed that excellent corrosion resistance is exhibited when three or more adsorption sites are formed by a structure in which three or more are added. When the number of atoms constituting the heterocyclic ring is 7 or more, it is difficult to move in the resin matrix because the molecular weight is too large, and as a result, it is difficult to reach the corrosion site and it is difficult to exhibit the rust prevention function. The heterocyclic ring preferably has a structure of 6 members or less. More preferably, a compound having a basic skeleton of a 5-membered heterocyclic ring structure containing at least one nitrogen and one sulfur is desirable.
Further, the functional group added to the five-membered ring structure is -SH, -N
When H ₂ , ＳS, ＮＨNH, ＝ O, the most excellent corrosion resistance is exhibited. By adding these functional groups, it is easy to obtain a resonance structure due to the transfer of the protons of the functional groups, and the proton dissociation energy from the molecular structure is reduced. It is considered that the adsorption of the added functional group to the metal surface accompanied by the proton dissociation further strengthens the adsorption of the cyclic compound to the metal surface, and as a result enhances the rust-preventive power.

The organic compound specified as a rust preventive in the present invention satisfies the above-mentioned structure, and can be used as a dangerous substance, a deleterious substance,
There are no particular restrictions on the chemical substances designated by the RTR method as long as they are low environmental impact compounds that are not subject to laws and regulations, but specific compounds include L-cysteine (L -cysteine), D-cysteine (D-cysteine), DL-cysteine (DL-cysteine)
), L-cystine (L-cystine), D-cystine (D-cystine), DL-cystine (DL-cystine), L
-Homocysteine (L-homocysteine), D-homocysteine (D-homocysteine), DL-homocysteine (DL-h
omocysteine), Ls, s'-methylenebiscysteine (Ls, s'-methylenebis [cysteine]), Ds, s'
-Methylenebiscysteine (Ds, s'-methylenebis [cyst
eine]), DL-s, s'-methylenebiscysteine (DL-s, s'-methylenebis [cysteine]), s-carbamyl-L-cysteine (s-carbamyl-L-cysteine), mercaptosuccinic acid (mercaptosuccinic) acid), dicarboxymethyl sulfide, bis (2-carboxyethyl) sulfide
oxyethyl) sulfide), dithiodiglycolic acid (dithiodi
glycolic acid), bis (2-carboxyethyl) disulfide, bis (2-carboxyethyl) disulfide
-Dimercaptosuccinic acid (meso-2,3-dimercaptosuccini
c acid), α, α'-dimercaptoadipic acid (meso-
α, α'-dimercaptoadipic acid), N-acetyl-
L-cysteine (N-acetyl-L-cysteine), 3-carboxymethylthio-L-alanine (3-carboxymethylthio-
L-alanine), s-methyl-L-cysteine (s-methyl
-L-cysteine), s-ethyl-L-cysteine (s-ethy
lL-cysteine), s-acetamidomethyl-L-cysteine (s-acetamidomethyl-L-cysteine), s- (2-aminoethyl) -L-cysteine (s- (2-aminoethyl) -L-cys)
teine), L-cystathionine,
Lanthionine, s-carboxyethyl-L-cysteine, s
-(2-amino-2-carboxyethyl) homocysteine (s- (2-amino-2-carboxyethyl) homocysteine) and the like.
4-dithiane-2,5-diol (1,4-dithiane-2,5-d
iol), 1,2-dithiane-4,5-diol (trans-
1,2-dithane-4,5-diol), 5-imino- (1,2,4)
Dithiazolidine-3-thione (5-imino- (1,2,4) dithiaz
olidine-3-thione), 2-amino-1,3,4-thiadiazole, 2-amino-5-mercapto-1,3,4-thiadiazole (2-amino-1,3,4-thiadiazole) am
ino-5-mercapto-1,3,4-thiadiazole), 2,5-dimercapto-1,3,4-thiadiazole (2,5-dimercapto
-1,3,4-thiadiazole), 2-mercapto-1,3,4-
Thiadiazole (2-mercapto-1,3,4-thiadiazole), 2
-Thioxo-4-thiazolidinone (2-thioxo-4-thiazol
idinone), 4-oxo-2-thioxo-3-thiazolidinylacetic acid
cid).

In the continuous phase mainly composed of a resin, the existence form of the organic compound specified as the rust inhibitor in the present invention is as follows:
When corrosion factors such as chloride ions enter the film, a small amount of an organic compound, which is a rust inhibitor, dissolves in water as a medium and reaches the metal surface. Not done. Specifically, it is preferably in a finely dispersed form in a continuous phase or dissolved in a resin constituting the continuous phase. In the case of an organic compound having a proton-dissociating functional group such as a carboxyl group, a hydroxyl group, and a thiol group, the organic compound may be present in a continuous phase in a state of forming a salt with a base such as ammonia and sodium hydroxide. .

The content of the organic compound as a rust preventive in the rust preventive treatment film cannot be specified unconditionally because it depends on the corrosion rate of the coated metal and the application.
It is preferred to be in the range of 1 to 1 g / m ² . Content is 1
If it is less than mg / m ² , the corrosion resistance is not sufficient. on the other hand,
Even if it exceeds 1 g / m ² , the corrosion resistance does not improve so much, and if it is economical, 1 g / m ² or less is sufficient. Since the basic mechanical properties of the rust-preventive coating such as workability are expressed by the properties of the resin phase, the ratio of the rust-preventive agent to the continuous phase containing resin as a main component must also be considered. The content of the rust inhibitor that does not inhibit the physical properties of the continuous phase is suitably 10% by mass or less, and preferably 5% by mass or less.

In the present invention, when there is an undercoating film containing no chromium at the interface between the rustproofing film and the metal, the composition of the film is not particularly limited.
It is preferably formed of a compound which is not subject to laws and regulations as a designated chemical substance of the TR method and has the ability to form a corrosion inhibiting film. For example, one or two selected from a metal compound containing one or more of zirconium, tungsten or a rare earth element, a phosphate, a phosphite, a silane compound, and an aqueous organic resin other than the metal compound More than one compound may be mentioned. In addition, as the aqueous organic resin used for the undercoating film, the above-mentioned water-soluble resin or water-dispersible resin, provided that it has a shielding effect of a corrosion factor,
There is no particular limitation.

In the present invention, the amount of the film formed on the surface of the metal product is not particularly limited, but is preferably in the range of 0.1 to 5 μm. When the adhesion amount is less than 0.1 μm, the barrier effect of the film may be insufficient and the corrosion resistance may be insufficient. On the other hand, if it exceeds 5 μm, the film becomes non-uniform, which causes a problem in appearance and raises the cost.

In the present invention, as a method of forming a rust-preventive film on a metal or a metal surface, a water-based treatment liquid is applied, dried, and then reached a surface temperature of 180 ° C. or less, preferably 150 ° C. The method is not particularly limited as long as it is a method capable of forming a uniform film at a temperature of not more than ° C. For example, after dipping a metal into a processing bath, roll coating, bar coating, brush coating, or spraying of an aqueous processing solution, and then heating and drying or reacting with hot air, etc., coating and film formation by other methods. Alternatively, the method is not limited to the method described here.

In order to further improve the corrosion resistance, the base coat and the rust preventive coat in the present invention may contain various additives having a corrosion inhibiting function. Examples of additives having a corrosion inhibiting function include tungstates, silane compounds, and colloidal silica. The rust preventive coating of the present invention may contain various organic or inorganic compounds in addition to the additives having a corrosion inhibiting function as long as the purpose is not impaired. Examples of such additives include inorganic sols such as alumina, titania, and zirconia, higher aliphatic alcohols, higher fatty acids, metal soaps, esters of higher fatty acids and other hydrocarbons, polyhydric alcohols and higher fatty acids. And solid lubricants such as monoamides or bisamides of higher fatty acids, polyethylene wax, paraffin, and fluoropolymers, various surfactants, organic or inorganic pigments, dyes, and crosslinking agents.

[0057]

The present invention will now be described by way of examples and comparative examples.
Although specifically described, the present invention is limited by these examples.
It is not specified. [Types of metal] (1) Cold rolled steel sheet (sheet thickness 0.8 mm) (2) EG: electrogalvanized steel sheet (sheet thickness 0.8 mm, female
(3) GI: hot-dip galvanized steel sheet (sheet thickness 0.8 mm,
[Formation of Undercoating Film] (1) Zirconium (Zr) -based Coating Fluorozirconic acid 0.5 as a base film forming component
g / l, phosphoric acid 0.3 g / l, hydrofluoric acid 0.3 g / l
Prepare a base treatment solution containing
The Zr content in the coating is changed from 0.03 to
0.07 g / m ^TwoTo obtain a Zr-based undercoat.
Was. (2) Aqueous resin-based film As a base film forming component, water of high acid value modified acrylic resin
Dispersion emulsion (resin solid content 25% by mass, pH: 8.
A surface treatment solution containing 400 g / l of 9) was prepared. Metal plate
After spraying these treatment liquids,
Total coating weight is about 0.3g / m^TwoSo that
To obtain an acrylic base film. [Formation of rust-proof coating] The following carboxyl group-containing aqueous solution
Resin, oxazoline group-containing aqueous resin, other aqueous resin
A rust-preventive treatment liquid was prepared using fats and organic compounds.
To the surface using a bar coater, or as described above.
Is applied by a bar coater to the steel sheet
Ultimate temperature 100 ° C (Hot air circulation drying oven temperature 250 ° C, steel plate
Drying and manufacturing at a time of 8.5 to 9.5 seconds from loading to unloading)
Filmed. Table 1 shows the constituent components of each film. As a rust inhibitor
The amount of the organic compound to be used in each case was
The amount was 1% by mass based on the total solid content of the fat and the organic compound. 1. Carboxyl group-containing aqueous resin (1) X-1 acrylic resin emulsion Resin solids: 27.6% by mass Dispersion viscosity: 1400 mPa · s (25 ° C.) pH: 8.8 Carboxyl group ammonium salt (—COONH)_Four)of
Content: 9.5% by mass of total resin solids Carboxyl group content: 2.5% by mass of total resin solids Carboxylic anhydride groups: None Dispersed particle diameter: 0.030 μm (2) X-2 acrylic resin emulsion Resin solids: 24.3% by mass Dispersion viscosity: 900 mPa · s (25 ° C.) pH: 8.3 Carboxyl group ammonium salt (—COONH_Four)of
Content: 2.8% by mass of total resin solids Carboxyl group content: 4.5% by mass of total resin solids Carboxylic anhydride groups: None Hydroxyl group content: 2.4% by mass Dispersed particle diameter: 0.085 μm (3 ) X-3 Urethane resin emulsion Resin solid content: 30.0% by mass Viscosity: 600 mPa · s (25 ° C.) pH: 8.3 Carboxyl group ammonium salt (—COONH_Four)of
Content: 7.8% by mass of total resin solids Carboxyl group content: 1.4% by mass of total resin solids Carboxylic anhydride groups: None Dispersed particle diameter: 0.024 μm Oxazoline group-containing aqueous resin (1) Y-1 acryl-styrene resin emulsion (Epocross K
-2010E, manufactured by Nippon Shokubai Co., Ltd.) Resin solid content: 40.1% by mass Viscosity: 14.0 mPa · s (25 ° C.) pH: 8.5 Oxazoline group content: 12.6% by mass of resin solid content
% (2) Y-2 acrylic-styrene resin emulsion (Epocross K
-2030E, manufactured by Nippon Shokubai Co., Ltd.) Resin solid content: 40.2% by weight Viscosity: 29.0 mPa · s (25 ° C.) pH: 8.9 Oxazoline group content: 12.6 mass of total resin solid content
% 3. Carboxyl group-containing aqueous resin, oxazoline group-containing
Aqueous resin other than resin Epoxy resin emulsion Resin solid content: 25.0% by mass Viscosity: 300 mPa · s (25 ° C.) pH: 8.5 Salt of carboxyl group, carboxyl group, carboxylic anhydride
Neither a chemical group nor an oxazoline group is contained. Dispersion particle diameter: 0.88 μm
3. Dispersed in water by ionic surfactant) Organic compounds used as rust inhibitors (1) I-1 2,3-dimercaptosuccinic acid (meso-2,3-dimercaptos)
uccinic acid)

[0058]

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(2) I-2 1,4-dithiane-2,5-diol (1,4-dithiane-
2,5-diol or 2,5-dihydroxy-1,4-dithiane)

[0060]

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(3) I-3 L-cystine

[0062]

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(4) I-4 succinic acid

[0064]

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(5) I-5 1,3,5-triazine-2,4,6-trithiol (1,3,5-triazine-2,4,6-trithiol or trithiocyanu
ric acid)

[0066]

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(6) I-6 2-mercaptonicotinic acid
d)

[0068]

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[Evaluation of Flat Plate Corrosion Resistance] After the back surface and the end surface of the steel plate on which the rust-proof coating was formed were tape-sealed,
A salt spray test based on JIS-Z2371 was performed,
The corrosion resistance was determined by measuring the area of rust occurrence after 40 hours. In the case of cold-rolled steel sheet, the evaluation is made based on the area ratio of red rust occurrence. Score 4: No red rust occurrence 3: Less than 5% red rust occurrence 2: 5% to less than 50% red rust occurrence 1: 50% or more red rust occurrence rate A score of 3 or higher was considered a pass.

In the case of EG and GI, evaluation was made based on the area ratio of white rust occurrence. Score 4: No white rust occurrence 3: White rust occurrence rate less than 5% 2: White rust occurrence rate 5% to less than 50% 1: White The rust generation rate was 50% or more, and a score of 3 or more was regarded as pass. [Evaluation of Corrosion Resistance of Processed Parts] After tape-sealing the back surface and the end surface of the steel plate on which the above-mentioned rust prevention treatment film was formed, a diameter of about 1 mm was measured from the back surface side of the steel sheet sample.
A 5 mm steel hemispherical projection is pressed to perform a so-called Erichsen process in which the surface of the sample is extended, so that the height of the dome becomes 7 mm, and then JIS-Z237.
A salt spray test in accordance with No. 1 was conducted, and the rust state of the dome portion after 120 hours was evaluated as follows.

In the case of a cold-rolled steel sheet, the evaluation was made based on the area ratio of red rust occurrence. Score 4: No red rust occurrence 3: Less than 5% red rust occurrence 2: 5% to less than 50% red rust occurrence 1: 50% red rust occurrence A score of 3 or higher was accepted.

In the case of EG and GI, the evaluation was made based on the area ratio of white rust occurrence. Rating 4: No white rust occurrence 3: Less than 5% white rust occurrence 2: 5% to less than 50% white rust occurrence 1: 1: White The rust generation rate was 50% or more, and a score of 3 or more was regarded as pass.

Tables 1 to 3 summarize the above evaluation results.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

A metal coated with a rust-preventive coating satisfying the constitutional requirements of the present invention has a smaller thickness and exhibits sufficient corrosion resistance as compared with the same metal coated with a coating not satisfying the requirements of the present invention. It can be seen that the products can be obtained (for example, the numbers 1 (Example) and 7 (Comparative Example), 2 (Example) and 12, 13 (Comparative Example), and 14 (Example) in Table 1 Nos. 21 to 24 (Comparative Example), No. 15 (Example) and 38, 39 (Comparative Example), No. 40 (Example) and 4
7 to 49 (Comparative Example)).

[0078]

The rust-preventive metal product of the present invention does not contain a substance having a high environmental load and has a rust-preventive layer on the metal surface which exhibits a thin film thickness, that is, low cost and sufficient corrosion resistance. I have. Therefore, the present invention can provide a highly corrosion-resistant metal product which is widely used in the fields of home appliances / OA equipment, construction / civil engineering, automobiles / vehicles, etc. and has low environmental concerns at low rust prevention cost. It can be said that this is an extremely valuable invention.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09D 201/08 C09D 201/08 C23C 28/00 C23C 28/00 Z (72) Inventor Takashi Iijima 20 Shintomi, Futtsu-shi, Chiba -1 Nippon Steel Corporation Technology Development Division (72) Inventor Kenichiro Tadokoro 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Corporation Technology Development Division F-term (reference) 4F100 AB01B AB03B AB10C AB15C AB16C AB18C AB21C AB31C AH02A AH02H AH03A AH03H AH04A AH04H AH07A AH07H AK01A AK12 AK25 AK51 AK53 AL05A AL07 BA02 BA03 BA07 BA10A BA10C EH46 EH71C GB07 GB32 GB41 GB48 GB90 JB02 JB02J 002 002 002 JC01 JC02 JC18 KA02 KA05 MA08 MA10 NA03 PA07 PC02 4K044 AA02 AB02 BA06 BA10 BA17 BA21 BB02 BB04 BC02 CA11 CA15 CA16 CA18 CA53

Claims (13)

[Claims] 1. A salt of a carboxyl group (—COO) _a Z _b
(However, Z is a cation having a valence of c, excluding hydrogen ions and cations having a high environmental load. In addition, the number of carboxylic acid residues a = the number of cations b × the valence c). Water-dispersible resin (A) and cyclic imino ether group (Wherein the number n of repeating units is an integer of 2 to 5, and the substituent -R
_A and -R _B is a hydrocarbon group having 1 to 10 hydrogen atoms or carbon atoms. ) Having a water-dispersible resin (B) having a pendant group as a pendant group and a non-cyclic structure containing one or more sulfur atoms as a main skeleton. Carboxyl group -CO
An organic compound (a) having a structure in which at least one OH and at least one functional group containing at least one of sulfur, nitrogen and oxygen are added, and at least two sulfur atoms are contained. The main skeleton is a heterocyclic structure or a heterocyclic structure containing at least one sulfur atom and at least one nitrogen atom, and one or more functional groups containing at least one of sulfur, nitrogen and oxygen are added to the main skeleton. A metal product having a rust-preventive treatment, comprising a rust-preventive treatment film made of at least one organic compound selected from organic compounds (b) having the above-mentioned structure. 2. The protection according to claim 1, wherein the water-dispersible resin (A) further has at least one of a carboxyl group —COOH and a carboxylic anhydride group (—CO) ₂ O. Rusted metal products. 3. The total amount of the salt of the carboxyl group, the carboxyl group, and the carboxylic anhydride group of the water-dispersible resin (A) is 0.1 to 15% by mass based on the total solid content of the water-dispersible resin (A). The rust-proofed metal product according to claim 1 or 2, wherein: 4. The method according to claim 1, wherein the content of the cyclic iminoether groups in the water-dispersible resin (B) is 1 to 25% by mass based on the total solid content of (B). Rust-proof treated metal products as described in the item 5. The total amount of a salt of a carboxyl group, a carboxyl group and a carboxylic anhydride group of the water-dispersible resin (A) is based on the content of the cyclic imino ether group of the water-dispersible resin (B). The rust-proofed metal product according to any one of claims 1 to 4, wherein the metal product has an equivalent weight of 0.05 to 50. 6. The rust-proof metal product according to claim 1, wherein the dispersed particle diameter of the water-dispersible resins (A) and (B) is 0.003 μm or more. . 7. The rust-proof metal product according to claim 1, wherein the organic compounds (a) and (b) have a structure in which two carboxyl groups —COOH are added to a main skeleton. 8. The method according to claim 1, wherein the organic compound (a) is sulfide-S
The rust-proofing metal product according to claim 7, wherein the main skeleton is a non-cyclic structure containing one or more bonds of any one of-, disulfide-SS- or thiol-SH. 9. The rust-proofing treatment according to claim 1, wherein the organic compound (b) has a main skeleton of a 5-membered heterocyclic ring structure containing at least one sulfur atom and at least one nitrogen atom. Metal products. 10. The organic compound (b) further comprises -SH,
-NH _2, = S, = NH or = anticorrosive treated metal product according to claim 9 one functional group represented by O or two or more is a structure attached to the main skeleton. 11. The rust-proof metal product according to claim 1, further comprising an undercoat film containing no chromium compound as a base of the rust-proof film. 12. The rust-proofed metal product according to claim 1, wherein the metal product is a steel plate. 13. The steel sheet according to claim 12, wherein the steel sheet has a plating layer made of any one of zinc, aluminum, cobalt, tin, and nickel, or an alloy containing these metal elements on the surface. Rust-proof metal products as described.