JPH08239776A - Rust preventing method and rust preventing composition for zinc-coated steel and uncoated steel - Google Patents

Abstract

PURPOSE: To provide a method for preventing the rusting of zinc-coated steel and uncoated steel exhibiting excellent rust preventiveness equal to or higher than the rust preventing method by using a chromating agent without using harmful chromium. CONSTITUTION: Fine-particle sulfur is incorporated by 0.5-200 pts.wt. to 100 pts.wt. of a soln. consisting of 1-80 pts.wt. of aq. resin and 99-20 pts.wt. of water to prepare a composition at >=pH7. The composition is applied on the zinc-coated or uncoated steel, and the steel is heated to 50-250 deg.C and dried. Alternately, the steel is heated to 50-200 deg.C, then the composition is applied, and the coated steel is dried and prevented from rusting.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rust preventive treatment method for uncoated steel such as zinc-based coated steel or cold-rolled steel sheet not coated with zinc-based coating, and zinc-based coated steel and rust-preventive composition for uncoated steel. Regarding the product, more specifically, a rust-preventive treatment method applied to primary rust-preventive treatment or coating base treatment of zinc-based coated steel and uncoated steel,
It also relates to a non-chromate coating type rust preventive composition used in the method.

[0002]

2. Description of the Related Art Zinc-based coated steel whose surface is coated with a metal containing zinc by plating or thermal spraying, and uncoated steel without the above-mentioned coating have been conventionally treated with chromium ion A chromate-based treating agent containing is widely used. As the chromate-based treatment agent,
For example, Japanese Patent Application Laid-Open No. 5-279867 discloses a coating type chromate-based treatment agent composed of chromium ions (Cr ⁶⁺ , Cr ³⁺ ) and a water-dispersible resin. However, since the chromate-based treatment agent contains toxic chromium ions, the cost of wastewater treatment for pollution-free,
There is a problem of adverse effects on the human body in the working environment, and there is also a risk of environmental pollution due to elution of chromium from a product having a chromate film formed by a treating agent.

As a method for solving the above-mentioned drawbacks, development of a non-chromate type anti-corrosion or anti-corrosion treatment agent containing no chromium or an anti-corrosion or anti-corrosion treatment method can be considered. As such, Japanese Patent Publication No. 5-37234 discloses:
There is disclosed a method of anticorrosion treatment in which hydrogen sulfide gas or an aqueous solution in which hydrogen sulfide gas is dissolved is brought into contact with a galvanized steel sheet or an uncoated steel sheet, and then coating is performed. Japanese Patent Fair 5-3879
No. 0 discloses a coating composition for anticorrosion containing a sulfide of a metal such as manganese, iron, nickel or cobalt, which has a solubility product in a specific range. Further, in Japanese Patent Publication No. 5-76552, after a coating film is formed on a metal surface capable of reacting with hydrogen sulfide, an aqueous solution containing hydrogen sulfide or steam containing hydrogen sulfide is brought into contact with the bottom surface of the coating film. An anticorrosion treatment method for producing sulfide is disclosed.

[0004]

However, a method of performing anticorrosion treatment of a coating base using hydrogen sulfide gas or an aqueous solution in which hydrogen sulfide gas is dissolved is a method for directly forming hydrogen sulfide gas and metal when forming a sulfide layer. Since it makes contact with the surface,
Hazardous hydrogen sulfide gas easily leaks into the environment, making industrial use difficult. Further, the coating composition for corrosion protection containing a metal sulfide is used by being applied to the metal surface, but when the water penetrates into the coating film or corrodes after a considerable period of time has passed after the coating, the composition The metal sulfide contained in the substance partially dissolves to release sulfide ions, and reacts with the metal to be coated to form a sulfide layer on the metal surface.
Compared to the method in which a sulfide layer is positively formed on the surface of the metal to be coated when the coating film is formed, the rust prevention and peeling resistance were inferior. The method of performing anticorrosion treatment of metal after coating by contacting an aqueous solution containing hydrogen sulfide or steam containing hydrogen sulfide is easy to generate hydrogen sulfide gas during work, which causes problems such as adverse effects on the human body in a work environment. was there.

As a non-chromate coating type rust preventive composition which has an excellent rust preventive power equal to or higher than that of a chromate treating agent without using harmful hydrogen sulfide gas and is excellent in peeling resistance, for example, , A rust preventive composition for zinc-based coated steel and uncoated steel in which a solution consisting of an aqueous resin and water contains a sulfide ion, or further, a sparingly soluble sulfide is dispersed It is also possible to do so.

When such a rust preventive composition for zinc-based coated steel and uncoated steel is used, a sulfide layer of a metal to be coated is positively formed on the metal surface by sulfide ions during coating film formation. It is possible to However, in order to further improve the rust preventive property, when a large amount of sulfide is added to such a rust preventive composition, sodium ion which is a counter ion,
A large amount of cations such as manganese ions remain in the coating film, which may increase the water permeability of the coating film.

The present invention has been made in view of the above circumstances, and is a zinc-based material that exhibits excellent rust-preventing properties equivalent to or better than the rust-preventing treatment method using a chromate-based treating agent without using harmful chromium. Anti-corrosion treatment method for coated steel and uncoated steel,
Also, a non-chromate coating type rust preventive composition having excellent rust preventive power equal to or higher than that of a chromate treatment agent,
In particular, it is an object of the present invention to provide a zinc-based coated steel and an uncoated steel which can be heat-dried after coating or can be coated and dried when heated.

[0008]

DISCLOSURE OF THE INVENTION The gist of the present invention is to provide a method for rust-preventing zinc-based coated steel and uncoated steel by using water-based resins 1-8.
To a solution of 0 parts by weight and 99 to 20 parts by weight of water, 0.5 parts by weight of fine particle sulfur is added to 100 parts by weight of the aqueous resin.
~ 200 parts by weight of the composition having a pH of 7 or more is applied to zinc-based coated steel or uncoated steel, and then the zinc-based coated steel or uncoated steel is heated to 50 to 250 ° C. Drying or heating the zinc-based coated steel or uncoated steel to 50 to 250 ° C. in advance, and then applying the composition and drying. Further, the gist of the present invention is to provide a rust preventive composition for zinc-coated steel and uncoated steel in a solution consisting of 1 to 80 parts by weight of an aqueous resin and 99 to 20 parts by weight of water, and to add fine particulate sulfur to the aqueous resin 1
The composition containing 0.5 to 200 parts by weight relative to 00 parts by weight and having a pH of 7 or more contains 500 to 100 parts by weight of phosphate ions.
5000 ppm, or 0.1 to 10000 ppm of sulfide ion, or 0.1 to 200 parts by weight of sparingly soluble sulfide with respect to 100 parts by weight of the aqueous resin, or sulfide ion. 0.1 to 10
000 ppm and a sparingly soluble sulfide are added to the above-mentioned aqueous resin 10
There is also a case where 0.1 to 200 parts by weight is contained with respect to 0 parts by weight. The present invention is described in detail below.

In the present invention, in the anticorrosive treatment of zinc-based coated steel and uncoated steel, finely divided sulfur is added to a solution containing 1 to 80 parts by weight of an aqueous resin and 99 to 20 parts by weight of water. A composition having a pH of 7 or more (hereinafter referred to as "composition I"), which is contained in an amount of 0.5 to 200 parts by weight based on parts, is used. The above-mentioned water-based resin has a function of forming a coating film to enhance the durability of a metal sulfide layer such as zinc sulfide and iron sulfide, and to improve the rust preventive power. The water-based resin is not particularly limited as long as it dissolves or disperses in water at pH 7 or higher, and examples thereof include a polyolefin resin, a polyurethane resin, a polyester resin, an acrylic resin, an epoxy resin, and an alkyd resin. Of these, polyolefin resins are preferred, and above all,
From the viewpoint of rust resistance, carboxylic acid-modified polyethylene is particularly preferable.

The mixing ratio of the aqueous resin and water in the solution comprising the above aqueous resin and water is 1 to 80 parts by weight of the aqueous resin and 99 to 20 parts by weight of water. When the amount of the aqueous resin is less than 1 part by weight and the amount of water exceeds 99 parts by weight, the film thickness of the coating film obtained by using the composition of the present invention is not sufficient and the rust preventive power is insufficient, and the aqueous resin is When the amount is more than 80 parts by weight and the amount of water is less than 20 parts by weight, the film thickness of the coating film obtained by using the above composition I becomes too large, and the fine particle sulfur contained or if necessary contained. Since the amount of sulfide dissolved in water is too small, it is limited to the above range. Aqueous resin is preferably 10 to 40 parts by weight and water is 90 to 60 parts by weight.

The finely divided sulfur is not particularly limited, and examples thereof include commercially available sulfur powder, colloidal sulfur, sulfur ink, etc., but those having a small particle size are preferable from the viewpoint of dispersibility and solubility. .

[0012] The content of the fine particulate sulfur in the composition I is 0.
5 to 200 parts by weight. When the content of the fine particulate sulfur is less than 0.5 parts by weight, the metal sulfide layer as the article to be coated is not sufficiently formed at the interface between the article to be coated and the coating film, and the rust preventive property deteriorates. When it exceeds 200 parts by weight, it does not release counter ions as in the case of sodium sulfide or manganese sulfide, so the rust preventive property is not particularly lowered, but the sulfur particles float on the surface of the coating film, The appearance is deteriorated due to graininess and the like, so that the content is limited to the above range.

In Japanese Unexamined Patent Publication No. 4-94772, zinc-rich paint is applied to an object to be coated so as to have a dry film thickness of 10 to 20 μm and dried, and then 100% of an acrylonitrile butadiene resin and a sulfur or sulfur compound vulcanizing agent are used. 0.2 ~
There is disclosed an anticorrosion coating method in which a primer composition containing a weight ratio of 100: 10 is applied and dried to a dry film thickness of 30 to 100 μm, and then a plastic powder is spray-coated to a film thickness of 1 to 3 mm. In the above invention, the sulfur or sulfur compound in the primer composition improves the adhesion between the article to be coated and the plastic coating film. Since the particulate sulfur in the present invention also improves the adhesion between the article to be coated and the top coating film, the present invention is the same as the above invention in this respect. However,
In the above invention, the adhesion of an object to be coated with zinc rich paint and a sprayed plastic coating film having a thickness of several mm through a primer composition coating film having improved adhesion by a sulfur or a sulfur compound vulcanizing agent. In contrast to improving the anti-corrosion effect and improving the anticorrosion effect of marine structures, the present invention provides that the fine particulate sulfur is a metal that is an object to be coated at the interface between the object to be coated and the coating film. By forming a stable sulfide layer, the adhesion between the top coat film having a thickness of about several μm to several tens of μm and the object to be coated is enhanced to exhibit peeling resistance, and zinc-based coated steel or uncoated steel It improves the corrosion resistance of. Therefore, the present invention is different in structure from the above-mentioned invention, and is completely different from the above-mentioned invention in its purpose and action.

The hydrogen ion concentration of the composition I of the present invention is p
It is H7 or more. When the pH is less than 7, the aqueous resin dispersed in water may gel, and when it contains a sulfide, hydrogen sulfide is generated to give off a bad odor, so that the content is limited to the above range. It is preferably pH 8 to pH 12.
The pH can be adjusted using, for example, aqueous ammonia or other amine compounds; metal hydroxides such as lithium hydroxide, potassium hydroxide and sodium hydroxide.

The composition I of the present invention may further contain other components. Examples of the other components include silica particles, pigments, surfactants and the like. Further, in order to improve the affinity between the aqueous resin and the sulfur particles, the pigment or the sparingly soluble sulfide particles, and further to improve the adhesion between the aqueous resin and the zinc or iron sulfide layer, a silane coupling agent is used. May be blended.

The above-mentioned silica particles are used as an agent for improving rust prevention, scratch resistance, coating adhesion and the like. The silica particles are not particularly limited as long as they have few impurities such as sodium and are weakly alkaline, and include, for example, Snowtex N (manufactured by Nissan Chemical Industries, Ltd.) and Adelite AT-20N.
(Asahi Denka Kogyo Co., Ltd.) and other commercially available silica sols; commercially available Aerosil powder silica particles and the like. The particle size of the silica particles is preferably 10 to 20 mμ.

Examples of the pigment include titanium oxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO), calcium carbonate (CaCO ₃ ), barium sulfate (BaSO ₄ ), alumina (Al ₂ O ₃ ). , Kaolin clay, carbon black, iron oxide (Fe ₂ O ₃ , F
It can include various coloring pigments such as organic pigments; e ₃ O ₄₎ inorganic pigments such. Examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and N- [2- (Vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane and the like can be mentioned.

A solvent may be used in order to improve the film-forming property of the aqueous resin and form a more uniform and smooth coating film. The solvent is not particularly limited as long as it is commonly used in paints, and examples thereof include alcohol-based, ketone-based, ester-based, and ether-based solvents.

In the present invention, the above composition I can be used to perform anticorrosion treatment on zinc-based coated steel or uncoated steel. The rustproofing treatment may be a method of applying the composition I to an object to be coated, heating the object to be coated with hot air after coating, and drying the composition, heating the object to be coated in advance, and then the composition described above. A method in which I is applied while hot and the remaining heat is used for drying may be used. The heating temperature is 50 to 250 ° C. in any of the above methods. If it is lower than 50 ° C, the evaporation rate of water is slow and a sufficient film-forming property cannot be obtained, so that the rust preventive power is insufficient, and if it exceeds 250 ° C, thermal decomposition of the water-based resin or the like occurs. "SST")
Since the water resistance and water resistance are deteriorated and the appearance is yellowed, the content is limited to the above range. It is preferably 70 to 100 ° C.
When the article to be coated is dried by heating with hot air after coating, the drying time is preferably 1 second to 5 minutes.

In the rust-preventing treatment, the coating film thickness of the composition I is preferably a dry film thickness of 0.1 μm or more. If it is less than 0.1 μm, the rust preventive power is insufficient. If the dry film thickness is too thick, it is uneconomical as a surface treatment for coating and is also inconvenient for coating.
Is about 20 μm. More preferably, it is 0.1 to 10 μm. In the rustproofing treatment, the coating method of the composition I is not particularly limited, and a commonly used roll coat,
It can be applied by air spray, airless spray, dipping or the like.

In the present invention, a rust preventive composition for zinc-based coated steel and uncoated steel (hereinafter, referred to as "rust-resistant rust preventive for zinc-based coated steel and uncoated steel", containing 500 to 5000 ppm of phosphate ion in the above composition I). Composition II ”), zinc-based coated steel and uncoated steel anticorrosive composition II with 0.1 to 0.1% sulfide ions.
Anticorrosion composition for zinc-based coated steel and uncoated steel containing 10000 ppm (hereinafter referred to as "rust-resistant composition III for zinc-based coated steel and uncoated steel"), zinc-based coated steel and anticorrosive composition for uncoated steel Rust-preventing composition for zinc-based coated steel and uncoated steel, which contains 0.1 to 200 parts by weight of poorly soluble sulfide in 100 parts by weight of water-based resin (hereinafter referred to as "zinc-based coated steel and uncoated steel"). Rust-preventive composition IV "), or zinc-coated steel and uncoated steel rust-preventive composition II containing sulfide ions.
A rust preventive composition for zinc-based coated steel and uncoated steel, containing 1 to 10000 ppm, and further containing 0.1 to 200 parts by weight of a sparingly soluble sulfide with respect to 100 parts by weight of an aqueous resin (hereinafter referred to as "zinc coating." Referred to as "rust preventive composition V for steel and uncoated steel")
Can also be used.

In the rust preventive composition II for zinc-based coated steel and uncoated steel, the source of the phosphate ions is not particularly limited, and examples thereof include phosphoric acid (H ₃ PO ₄ ) and sodium phosphate ( Na ₃ PO ₄ ), sodium monohydrogen phosphate (Na ₂ HPO ₄ ), sodium dihydrogen phosphate (Na
H ₂ PO ₄ ), potassium phosphate (K ₃ PO ₄ ), potassium monohydrogen phosphate (K ₂ HPO ₄ ), potassium dihydrogen phosphate (KH ₂ PO ₄ ), ammonium phosphate ((NH ₄ ))
₃ PO ₄ ), ammonium monohydrogen phosphate ((NH ₄ ) ₂
HPO ₄ ), ammonium dihydrogen phosphate ((NH ₄ ) H
₂ PO ₄ ) and the like, and further, low molecular weight amine salts of phosphoric acid such as hydrazinium phosphate, and relatively low molecular weight phosphoric acid esters such as ethyl phosphate. Of these, salts with volatile bases such as ammonium phosphate, ammonium monohydrogen phosphate and ammonium dihydrogen phosphate; low molecular weight amine salts of phosphoric acid such as hydrazinium phosphate are preferred.

The content of the above phosphate ion is 500 to 5
It is 000 ppm. The content of phosphate ion is 500p
If it is less than pm, the formation of a metal phosphate layer such as a zinc phosphate layer at the interface between the metal to be coated and the coating film will be insufficient and rustproofing of the zinc sulfide layer formed by sulfide ions will occur. The effect of supplementing sex is lost. If the content of phosphate ions exceeds 5000 ppm, the electrolytic mass in the coating film increases and the water permeability of the coating film increases, so that SST resistance and water resistance are reduced. Also, the addition of an excess of phosphate ions causes the aqueous resin to gel in the rust preventive composition over time, and thus deteriorates the storage stability of the rust preventive composition. It is preferably 1000 to 5000 ppm.

Anticorrosion composition for the above-mentioned zinc-based coated steel and uncoated steel
In the compound III, the sulfide ion is HS^-Or
S^2-Is. The above sulfide ions are applied at the time of application, heat drying, etc.
At the surface of the metal to react with the metal to be coated
It has a function of forming a sulfide layer. Of the above sulfide ion
As a supply source, in a solution consisting of an aqueous resin and water,
Soluble in water that can dissolve sulfide ions above 0.1 ppm
It is not particularly limited as long as it is a neutral sulfide.
Umm (Na₂S), potassium sulfide (K₂S), Ammonium sulfide
Monium ((NH_Four)₂S), ammonium hydrogen sulfide
(NH_FourHS), calcium sulfide (CaS), sulfide strike
Rontium (SrS), aluminum sulfide (Al
₂S₃), Barium sulfide (BaS), germanium sulfide
(GeS), manganese sulfide (MnS), lanthanum sulfide
(La₂S₃) Etc. can be mentioned. These
Manganese sulfide (MnS), ammonium sulfide ((N
H_Four)₂S), ammonium hydrogen sulfide (NH_FourHS)
preferable. These may be used alone or in combination of two or more.
The above may be used in combination.

The content concentration of the sulfide ion is 0.1 to 10,000 pp in a solution composed of an aqueous resin and water.
m. When the content is less than 0.1 ppm, the interface between the object to be coated and the coating film of the zinc-based coated steel and the rust preventive composition III for the uncoated steel during coating and drying of the rust preventive composition III for the zinc-based steel and the uncoated steel , A uniform sulfide layer of zinc or iron could not be formed, and when it exceeded 10000 ppm, water-soluble matter remained excessively in the coating film of the rust preventive composition III for zinc-based coated steel and uncoated steel. As a result, the water permeability of the coating film increases and the rust preventive power decreases due to the occurrence of blisters (blisters).
The odor peculiar to sulfide becomes a problem. Preferably 1-100
It is 0 ppm.

In the rust preventive composition IV for zinc-based coated steel and uncoated steel, particles of a sparingly soluble sulfide are further added to the rust preventive composition II for zinc-based coated steel and uncoated steel. The particles of the hardly soluble sulfide, when water penetrates into the rust preventive composition coating film in a corrosive environment, gradually releases sulfide ions, and at the interface between the article to be coated and the rust preventive composition coating film. Since the corrosion site of the metal sulfide layer such as zinc sulfide and iron sulfide which has been formed in advance is repaired, it has the function of ensuring the achievement of the object of the present invention. However, at this time, a cation that is a counter ion may be left as it is at the interface or in the coating film to promote permeability and water permeability of anions such as chlorine ions. For this reason, in the present invention, fine particle sulfur that does not cause the above-mentioned phenomenon and is excellent in rust prevention is used as a main constituent element of the composition. The poorly soluble sulfide is not particularly limited as long as it dissociates sulfide ions in an aqueous solution, and examples thereof include manganese sulfide (MnS ₂ ), molybdenum sulfide (MoS ₃ , MoS ₄ ), iron sulfide (Fe
S, FeS ₂ , Fe ₂ S ₃ ), vanadium sulfide (V
S ₄ , V ₂ S ₅ , V ₂ S ₃ ), nickel sulfide (Ni
S), lanthanum sulfide (La ₂ S ₃ ), antimony sulfide (Sb ₂ S ₃ ) and the like.

The content of the sparingly soluble sulfide is based on the water-based resin 1
It is 2.5 to 200 parts by weight with respect to 00 parts by weight. 2.
If it is less than 5 parts by weight, the supply of sulfide ions is too small to sufficiently repair the metal sulfide layer such as zinc sulfide and iron sulfide, so there is no rust preventive effect, and if it exceeds 200 parts by weight, The amount of the sparingly soluble sulfide becomes excessive and the amount of the cation which is a counter ion remains in the coating film increases, the water permeability increases, and the rust preventive power decreases. It is preferably 5 to 50 parts by weight.

Further, in the present invention, the rust preventive composition II for zinc-based coated steel and uncoated steel is added with sulfide ions in an amount of 0.1 to 0.1.
The above-mentioned rust preventive composition V for zinc-based coated steel and uncoated steel is prepared by containing 10000 ppm and further containing 0.1 to 200 parts by weight of a hardly soluble sulfide with respect to 100 parts by weight of an aqueous resin. As a source of the sulfide ions, those which can be used in the zinc-based coated steel and the uncoated steel anticorrosion composition III are referred to as the zinc-based coated steel and the uncoated steel anticorrosion composition III. It can be used in a similar content. As the sparingly soluble sulfide, those which can be used for the zinc-based coated steel and the uncoated steel anticorrosive composition IV are the same as those for the zinc-based coated steel and the uncoated steel anticorrosive composition IV. It can be used in the content.

In the present invention, the rust preventive composition II for zinc-based coated steel and uncoated steel, the rust preventive composition III for zinc-based coated steel and uncoated steel, the rust preventive composition for zinc-based coated steel and uncoated steel Composition IV, anticorrosive composition V for zinc-based coated steel and uncoated steel
Can also be used for anticorrosion treatment of zinc-based coated steel or uncoated steel. The rustproofing treatment can be performed in the same manner as the rustproofing treatment performed using the composition I of the present invention described above.

[0030]

The composition I of the present invention, the anticorrosive composition II for zinc-based coated steel and uncoated steel, the anticorrosive composition III for zinc-based coated steel and uncoated steel, the anticorrosive composition for zinc-based coated steel and uncoated steel Rust composition I
V, and anticorrosive composition for zinc-based coated steel and uncoated steel V
Contains particulate sulfur. Sulfur is stable in water and insoluble, but is slightly dissolved in acid or alkali to form sulfide ions. Therefore, in a corrosive environment, metal sulfides are formed by sulfide ions in which sulfur is dissolved, and the corroded portion of the metal sulfide layer that has been formed in advance is repaired. Also, the solubility of sulfur is promoted by heating. Therefore, by setting the pH of the aqueous resin aqueous solution to 7 or more, a small amount of sulfur is dissolved during thermal drying, and a stable sulfide layer is formed on the surface of the metal that is the object to be coated. Further, since sulfur has a property of directly reacting with many metals to form a sulfide when heated, the sulfur and the metal to be coated react directly with each other during heating and drying, and the surface of the coated object A sulfide layer is formed on.

In general, sulfides of metals such as iron and zinc are highly stable. For example, iron naturally exists as pyrite, and 90% or more of zinc is produced as sphalerite for a long time. It does not change. In addition, as can be seen from the solubility product, it is extremely insoluble in water. Furthermore,
The stability of sulfides of metals such as iron and zinc was also confirmed by experiments. For example, when the galvanized surface was changed to zinc sulfide by sulfurization treatment, the corrosion current density was measured, and it was 10 % Or less, and it was found that there is a corrosion inhibition effect equivalent to or higher than the corrosion inhibition effect of the chromate-based treatment agent. Therefore, according to the rustproofing method of the present invention, an extremely stable rustproof layer made of a metal sulfide layer such as iron sulfide or zinc sulfide is formed. Further, in the rustproofing method of the present invention, hydrogen sulfide gas or an aqueous solution thereof is not used, which is safe.

Anticorrosion composition II for zinc-based coated steel and uncoated steel of the present invention II, anticorrosion composition I for zinc-based coated steel and uncoated steel I
II, the rust preventive composition IV for zinc-based coated steel and uncoated steel, and the rust preventive composition V for zinc-based coated steel and uncoated steel further contain a phosphate ion. Phosphate ions also react with the metal to be coated to form phosphates such as zinc phosphate, iron phosphate, etc., which are insoluble in water, so no sulfide layer is formed. It repairs the metal base part and exerts a rust preventive effect synergistically with the effect of sulfur particles or soluble or sparingly soluble sulfides. These phosphates are less stable than sulfides in a neutral or alkaline environment, but are more stable than sulfides in an acidic environment. Therefore, in an acidic environment such as the anode site under a corrosive environment, the phosphate ions concentrated and eluted at the interface between the coating object and the coating film react with the ions of the metal that is the coating object such as zinc and iron. Since a stable phosphate layer can be formed, it can function as a rust-preventing aid and improve the acid resistance of rust-preventing treatment.

[0033]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 20% by weight of a polyethylene resin emulsion as an aqueous resin was mixed with 80% by weight of water. Resin 1 with sulfur powder
0.5 part by weight was added to 00 parts by weight, and the mixture was stirred and dispersed with a disper for 30 minutes to adjust the pH to 9.0 to obtain a composition. The obtained composition was preliminarily heated to a plate temperature of 80 ° C.
Hot-dip galvanized steel sheet (Z-2
7, manufactured by Nippon Test Panel Co., 70 x 150 x 2.3 m
m) with a bar coat (# 5) and a dry film thickness of 2 to 3 μm
It was applied so that The surface of the hot-dip galvanized steel sheet is polished with Scotch bright, and then degreased with an alkaline degreasing agent (SCL53, manufactured by Nippon Paint Co., Ltd.), washed with water,
Used after drying.

The hot-dip galvanized steel sheet coated with the obtained composition and dried was evaluated for the following items. The results are shown in Table 1.
It was shown to. (1) SST 5% saline was sprayed onto the composition-coated surface at 35 ° C., and the degree of white rust after 72 hours was evaluated on a scale of 5 points. (2) Water resistance test After immersion in tap water for 1 week at room temperature, the degree of whitening of the surface was evaluated on a scale of 5 points.

Examples 2 to 8 and Comparative Examples 2 to 3 Sulfur powder was used at the addition amounts shown in Table 1, adjusted to the pH shown in Table 1, and preheated to bring the plate temperature to the temperature shown in Table 1. A composition was obtained, coated, dried and evaluated in the same manner as in Example 1 except that the above was performed. The results are shown in Table 1.

Example 9 A composition was obtained in the same manner as in Example 1, except that sulfur powder was used in the addition amount shown in Table 1 to adjust the pH to be shown in Table 1.
The resulting composition I was applied to bar coat (# 5) in Example 1
After coating so as to have the same film thickness as above, it was dried at 250 ° C for 5 seconds and evaluated. The results are shown in Table 1.

Comparative Example 1 A composition was prepared, coated, dried and evaluated in the same manner as in Example 1 except that sulfur powder was not used. The results are shown in Table 1.

Comparative Example 4 A composition was prepared, coated, dried and evaluated in the same manner as in Example 9 except that the drying temperature was set to the temperature shown in Table 1 and the drying time was set to 5 minutes. The results are shown in Table 1.

Comparative Example 5 Example 9 except that the drying temperature was set to the temperature shown in Table 1.
A composition was obtained, coated, dried and evaluated in the same manner as in.
The results are shown in Table 1.

Comparative Example 6 In the same manner as in Example 1 except that 5.0 parts by weight of strontium chromate was added to 100 parts by weight of the resin in place of the sulfur powder to adjust the pH shown in Table 1.
The composition was obtained, coated, dried and evaluated. The results are shown in Table 1.

[0042]

[Table 1]

Examples 10 to 18 and Comparative Examples 8 to 10 Sulfur powders were used in the addition amounts shown in Table 2, and ammonium phosphate ((NH ₄ ) ₃ PO ₄ ) was added to phosphate ions ((PO ₄ ) ^3- ) was added to the concentration shown in Table 2 and adjusted to the pH shown in Table 2 in the same manner as in Example 1 to obtain a rust preventive composition, coating, drying, and evaluation. did. The results are shown in Table 2. However, SST evaluated the degree of white rust after 312 hours on a scale of 5 points.

Comparative Example 7 Sulfur powder and ammonium phosphate ((NH ₄ ) ₃ PO
_A rust preventive composition was obtained, coated, dried and evaluated in the same manner as in Example 10 except that ₄ ) was not used. The results are shown in Table 2.

Comparative Example 11 Ammonium phosphate ((NH ₄ ) ₃ PO ₄ ) was not used, and 5.0 parts by weight of strontium chromate was added to 100 parts by weight of the resin instead of the sulfur powder. A rust preventive composition was obtained, coated, dried and evaluated in the same manner as in Example 10 except that the pH was adjusted. The results are shown in Table 2.

[0046]

[Table 2]

Examples 19 to 25 Sulfur powder and ammonium phosphate ((NH ₄ ) ₃ PO
₄ ) was used at the addition amount and the phosphate ion concentration shown in Table 3, respectively, and the water-soluble sulfide shown in Table 3 was used at the sulfide ion concentration shown in Table 3 to adjust the pH shown in Table 3. A rust preventive composition was obtained, coated, dried and evaluated in the same manner as in Example 1 except for the above. The results are shown in Table 3. However, SST evaluated the degree of white rust after 384 hours on a scale of 5 points.

Examples 26-29 Sulfur powder and ammonium phosphate ((NH ₄ ) ₃ PO
₄ ) was used at the addition amount and the phosphate ion concentration shown in Table 3, respectively, and the sparingly soluble sulfide shown in Table 3 was dispersed at the addition amount shown in Table 3 to adjust the pH shown in Table 3. In the same manner as in Example 1, a rust preventive composition was obtained, coated, dried and evaluated. The results are shown in Table 3. However, SST
Evaluated the degree of white rust after 384 hours on a scale of 5 points.

Examples 30-32 Sulfur powder and ammonium phosphate ((NH ₄ ) ₃ PO
₄ ) is used at the addition amount and the phosphate ion concentration shown in Table 3, respectively, and the water-soluble sulfide and the sparingly soluble sulfide shown in Table 3 are used at the sulfide ion concentration and the addition amount shown in Table 3, respectively. However, except that the pH is adjusted as shown in Table 3,
In the same manner as in Example 1, a rust preventive composition was obtained, coated, dried and evaluated. The results are shown in Table 3. However, SST
Evaluated the degree of white rust after 384 hours on a scale of 5 points.

Comparative Example 12 Sulfur powder, ammonium phosphate ((NH ₄ ) ₃ P
O ₄ ) and water-soluble sulfides are not used, and the pH values shown in Table 3
A rust preventive composition was obtained, coated, dried and evaluated in the same manner as in Example 19 except that the above adjustment was made. The results are shown in Table 3.

COMPARATIVE EXAMPLE 13 Ammonium phosphate ((NH ₄ ) ₃ PO ₄ ) and water-soluble sulfide were not used, and 5.0 parts by weight of strontium chromate was added to 100 parts by weight of resin instead of sulfur powder. A rust preventive composition was obtained, coated and dried in the same manner as in Example 19 except that the pH was adjusted to that shown in Table 3.
evaluated. The results are shown in Table 3.

[0052]

[Table 3]

[0053]

EFFECTS OF THE INVENTION Since the present invention has the above-mentioned constitution, it does not use harmful chromium and has an excellent anticorrosive power equivalent to or more than the anticorrosive treatment method using a chromate-based treating agent. Moreover, it is possible to realize a rust preventive treatment method for zinc-based coated steel and uncoated steel that does not generate hydrogen sulfide and can be easily used industrially. Further, according to the present invention, a non-chromate coating type rust preventive composition having an excellent rust prevention power equal to or higher than that of a chromate treatment agent, which can be heat-dried after being applied to zinc-based coated steel and uncoated steel. Alternatively, it is possible to obtain a product that can be applied and dried when heated.

Front page continuation (72) Inventor Kazuhiko Usuki 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka, Japan Paint Co., Ltd. (72) Inventor Yuichi Yoshida 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (5)

[Claims] 1. An aqueous resin 1 to 80 parts by weight and water 99 to 2
A zinc-coated steel or uncoated steel is coated with a composition having a pH of 7 or more, which is obtained by adding 0.5 to 200 parts by weight of fine particle sulfur to 100 parts by weight of the aqueous resin in a solution consisting of 0 parts by weight. Then, the zinc-based coated steel or uncoated steel is heated to 50 to 250 ° C. and dried, or the zinc-based coated steel or uncoated steel is previously heated to 50 to 250.
A rust preventive treatment method, which comprises heating to ℃, and then applying the composition and drying. 2. Aqueous resin 1 to 80 parts by weight and water 99 to 2
A solution containing 0 part by weight of fine particle sulfur in an amount of 0.5 to 200 parts by weight with respect to 100 parts by weight of the aqueous resin, and having a pH of 7 or more, is added with 50 parts of phosphate ion.
A rust preventive composition for zinc-based coated steel and uncoated steel, which is characterized by containing 0 to 5000 ppm. 3. The rust preventive composition for zinc-based coated steel and uncoated steel according to claim 2, further containing sulfide ions in an amount of 0.1 to 10.
A rust preventive composition for zinc-based coated steel and uncoated steel, which is characterized by containing 000 ppm. 4. The rust preventive composition for zinc-based coated steel and uncoated steel according to claim 2, further comprising 0.1 to 200 parts by weight of a hardly soluble sulfide with respect to 100 parts by weight of the aqueous resin. A rust-preventive composition for zinc-based coated steel and uncoated steel. 5. The rust preventive composition for zinc-based coated steel and uncoated steel according to claim 2, further containing 0.1 to 10 sulfide ions.
000 ppm and a sparingly soluble sulfide are added to the above-mentioned aqueous resin 10
A rust preventive composition for zinc-based coated steel and uncoated steel, characterized in that it is contained in an amount of 0.1 to 200 parts by weight based on 0 parts by weight.