JPS62255138A - Coated steel material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coated steel material, and more particularly to a coated steel material with improved adhesion and corrosion resistance between the steel material and an organic coating film.

(Prior Art) In order to prevent corrosion of steel materials such as steel plates and steel pipes, the surfaces of steel materials are increasingly coated with organic resin paints having excellent chemical stability. However, in recent years, the environment in which coated steel materials are used has changed to a wide range of temperature environments, from cold regions to tropical regions, and has also come to be applied to graft-corrosive environments such as coasts and river areas, ranging from low temperatures to high temperatures. There is a growing need for coated steel materials that have excellent anti-corrosion performance over a wide temperature range. In order to provide coated steel with excellent long-term corrosion protection, it is necessary to firmly adhere an organic coating to the surface of the steel.

Conventionally, several methods have been proposed in which the surface of the steel material is pre-treated in order to firmly adhere an organic coating film to the surface of the steel material. For example, as seen in JP-A No. 59-11.5832, as shown in FIG. As seen in Japanese Patent No. 60-23038, there is a coated steel material in which a silane coupling agent layer 4 is interposed between the steel material 1 and the epoxy resin coating 5, as shown in FIG.

(Problems to be Solved by the Invention) However, such coated steel materials have the following problems: (a) Painted steel materials using a chrome-1 treatment agent as a surface treatment agent for steel materials cannot be exposed to high-temperature water or salt water for a long period of time. When immersed, the chromate treatment agent layer has a small shielding effect against the permeation of water and salt water, so water and salt water accumulate at the interface between the steel material and the chromate treatment agent layer, and the shrinkage force of the organic coating acts to reduce the adhesion. decreases.

(b) For painted steel materials that use a silane coupling agent as a surface treatment agent for steel materials, if immersed in high-temperature water or salt water for a long time, the silane coupling agent layer has a small shielding effect against the permeation of water and salt water, so the steel material Water and salt water accumulate at the interface between the organic coating and the chromate-treated layer, and the shrinkage force of the organic coating acts to reduce adhesion.

Conventional techniques have had the following two problems, and it has been difficult to obtain coated steel materials with excellent adhesion, high-temperature water resistance, and salt water resistance.

An object of the present invention is to provide a coated steel material that has good adhesion between the steel material and an organic coating film and has excellent water resistance and salt water resistance at high temperatures.

(Means for Solving the Problems) As a result of intensive studies to solve the above-mentioned problems, the inventor of the present invention applied a chromate treatment agent containing a silica-based dispersant to the surface of a steel material and baked it. By applying a polytitanocarbosilane treatment agent and baking it, and then applying a mixed treatment agent of a chelating agent and a silane coupling agent on the base and baking it, it becomes strong and durable after being immersed in high-temperature water or salt water. It was discovered that a coated steel material with extremely excellent adhesion properties can be obtained, leading to the present invention.

That is, as shown in FIG. 1, the present invention includes a chromate treatment agent layer 2 containing a silica-based dispersant on the surface of a steel material 1, a polytitanocarbosilane treatment agent layer 3, and a mixed treatment of a chelating agent and a silane coupling treatment agent. The present invention relates to a coated steel material characterized in that a chemical layer 4 and an organic coating film 5 are sequentially laminated.

(for production) Hereinafter, the present invention will be explained in detail.

The steel materials used in the present invention include steel plates such as cold-rolled steel plates, hot-rolled steel plates, and thick steel plates, H-shaped steel, ■shaped steel, ■, shaped steel such as shaped steel, steel sheet piles, steel bars, steel wire, and hammered iron pipes , steel pipes and steel pipe sheet piles.

In addition, the surfaces of these steel sheets, sections, steel sheet piles, steel bars, steel wires, steel pipes, and steel pipe sheet piles are plated with zinc, tin, nickel, chromium, aluminum, zinc-aluminum, zinc-nickel, zinc-nickel-cobalt, etc. It may be a steel material that has been subjected to.

The chromate treatment agent used in the present invention is a chromic acid aqueous solution prepared by dissolving chromic acid anhydride (CrO2) in distilled water, and is partially reduced with an organic reducing agent to produce hexavalent chromium ions and trivalent chromium ions. and a silica-based dispersant, but if necessary, part of the chromic acid can be replaced with water-soluble chromate or water-soluble dichromate; Added metal salt. Organic reducing agents used for partial reduction of chromium from hexavalence to trivalence include monohydric alcohols such as methyl alcohol and ethyl alcohol, polyhydric alcohols such as polyethylene glycol, polyvinyl alcohol, and sorbitol, jetanolamine, Alkylolamines such as triethanolamine, aromatic polyhydric alcohols such as pyrogallol, saturated carboxylic acids such as formic acid, acetic acid, and oxalic acid, and unsaturated carboxylic acids such as succinic acid and adipic acid are used. These reducing agents are used in amounts necessary to maintain the desired ratio of hexavalent chromium to total chromium.

The desired ratio is a weight ratio of hexavalent chromium to total chromium in the range of 0.25 to 0.85. Regarding this ratio, if the weight ratio of hexavalent chromium to total chromium is less than 0.25, the corrosion resistance of the chromate treatment agent layer will be significantly reduced, and if this weight ratio is more than 0.85, there will be no adhesion between the steel surface and the chromate treatment agent layer. sex is significantly reduced.

Water-soluble chromates and dichromates that partially replace chromic acid are chromates and dichromates of alkali metals, alkaline earth metals, iron group metals, and the like. The silica-based dispersant to be mixed with the chromate treatment agent may be an inorganic silica-based dispersant such as colloidal silica, silica fine powder, silicomolybdate fine powder, silicotungstic acid fine powder, or a silica-based dispersant that is decomposed in the chromate treatment agent. Tetrame-1-hexysilane, tetraeth-1-xysilane, etc. that can be a silica source
These are laalkoxysilanes, and one type or a mixture of two or more of these is used.

The above-mentioned silica-based dispersant has the effect of stabilizing the dispersion of each component in the chromate treatment solution and making the film obtained by applying the treatment agent to the steel surface insoluble in water. At the same time, it is strongly bonded with the polytitanocarbosilane molecules in the polytitanocarbosilane treatment agent applied to the upper layer of this film through a condensation reaction, and has a remarkable effect on the adhesion between both layers. be. The amount of silica-based dispersant mixed is 2 to 45 g per 100 g of chromic anhydride.
Mix in the following proportions. If the amount of the silica-based dispersant mixed is less than 2 g, the above effect will hardly be achieved, and if the amount mixed is more than 45 g, the fluidity of the Chrome-1 treatment agent will deteriorate significantly, and the smoothness of the coating obtained by applying it to the steel surface will deteriorate. undesirable because it inhibits

Before applying the above-mentioned chromate treatment agent to the surface of the steel material, oil, scale, etc. on the surface of the steel material are removed by degreasing, pickling, sandblasting, Grid Plus 1~ treatment, shot blasting, etc. When a chromate treatment agent is applied to the steel surface from which oil, scale, etc. have been removed, hexavalent chromium is reduced by the oxidation effect on the steel surface and heating after application, promoting insolubility and forming an inorganic film that is poorly soluble in water. Become. The baking temperature of the chromate treatment agent is 120 to 25 at the steel surface temperature.
0°C is suitable. If the steel surface temperature is below 120℃, it will take a very long time to insolubilize the chromate treatment agent layer, making it unsuitable for practical use.If the steel surface temperature exceeds 250℃, the chromate treatment agent will be excessively reduced rapidly. This progresses and actually worsens the corrosion resistance. Further, the amount of the chromate treatment agent deposited is preferably 50 to 1200 .mu./i based on the total chromium weight. If the amount of this adhesion is less than 50 μ/n, the anticorrosion properties of Chromate treatment cannot be exhibited, and if it is more than 1200 μ/m2, a strong film will not be formed, and the adhesion test will show cohesive failure within the chromate treatment agent film. occurs and does not exhibit high adhesive strength.

The polytitanocarbosilane treatment agent used in the present invention is a treatment agent obtained by diluting polytitanocarbosilane with an organic solvent. The polytitanocarbosilane described in ``2'' is a resin obtained by mixing and polymerizing polycarbosilane and titanium rhabdoxide.

The above polycarbosilane is a resin obtained by mixing and polymerizing polydimethylsilane having the following molecular structure, and polyborodiphenylsiloxane having the following molecular structure.

In addition, the above organic solvents include N-methyl-pyrrolidone,
It is a solvent that can dissolve polytitanocarbosilane such as tetrahydrofuran, xylene, benzene, and toluene to form a uniform solution. If the solution becomes non-uniform, it is difficult to smooth the film obtained by applying the above-mentioned polytitanocarbosilane to the surface of the steel material coated with the above-mentioned chromate treatment agent, and the anti-corrosion performance becomes non-uniform, so it is preferable. do not have.

The above polytitanocarbosilane treatment agent was added to the above chromate treatment agent.
By applying the treatment agent to the surface of the steel material and heating it, the polytitanocarbosilane molecules in the polytitanocarbosilane treatment agent become firmly bonded with the silica-based dispersant in the treatment agent layer. At the same time, the adhesion between the polytitanocarbosilane treatment agent layer and the chromate treatment agent layer is significantly improved.
-Ti-C-O-based inorganic coating, and the barrier effect of the coating against permeation of water and salt water is significantly improved.

The above polytitanocarbosilane treatment agent is applied to the surface of the steel material coated with the above chromate treatment agent so that the polytitanocarbosilane treatment agent layer has a thickness in the range of 0.1 to 50 μm. is desirable. Regarding the film thickness of the above-mentioned polytitanocarbosilane treatment agent layer, if the film thickness of the polytitanocarbosilane treatment agent layer is 0.1 μm or less, there is almost no shielding effect against the permeation of water and salt water, and if it is 50 μm or more, It takes a long time to develop adhesive properties.

Regarding the heating temperature when applying and heating the above-mentioned polytitanocarbosilane treatment agent on the surface of the steel material coated with the above-mentioned chromate treatment agent, Heat to 400-1200°C. If the above-mentioned heating temperature is 400° C. or lower, the above-mentioned effect will be small, and if the above-mentioned heating temperature is 1200° C. or higher, thermal deterioration of the above-mentioned polytitanocarbosilane treatment agent layer will occur, which is not preferable.

The mixed treatment agent of a chelating agent and a silane coupling agent used in the present invention is preferably prepared by mixing an aqueous solution of a chelating agent and an aqueous solution of a silane coupling agent.

Regarding the preparation method of the above-mentioned mixed treatment agent, the optimum pH value is determined to dissolve the Clean-1 ~ agent in water to make a uniform aqueous solution, and the silane coupling agent is dissolved in water to make a uniform aqueous solution. In addition, since the optimal pH value for sufficiently hydrolyzing the silane coupling agent and converting it into a highly reactive silanol compound is different, the two are made into separate aqueous solutions,
You will need to mix it later to make a homogeneous aqueous solution. If the above-mentioned mixed treatment agent is uneven, it will be difficult to smooth the coating obtained by applying the mixed treatment agent on the upper layer of the steel coated with the above-mentioned polytitanocarbosilane treatment agent, and the adhesion will be uneven. This is not preferable because it deteriorates corrosion resistance.

Next, a mixed treatment agent of a chelating agent and a silane coupling treatment agent used in the present invention will be explained.

As the killing agent, ethylenediaminetetraacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetraacetic acid,
With water-soluble chelating agents such as aminocarboxylic acids such as N-oxyethylenediaminetriacetic acid, ethylene glycol bis(β-aminoethyl ether)tetraacetic acid, and ethylenediaminetetrapropionic acid, and alkylolamines such as jetanolamine and triethanolamine. It doesn't matter if you have it. A chelating agent may not dissolve simply by adding it to water, but by dissolving it in water whose pH has been adjusted using an alkali such as ammonia and a weak acid such as acetic acid or phosphoric acid, a uniform aqueous solution can be obtained6. The pH value is sufficient as long as the above chelating agent can be dissolved as a stable aqueous solution. For example, for ethylenediaminetetraacetic acid, an appropriate pH value is 5.6 to
It is in the range of 6.9. In addition, the silane coupling agent is
γ-anilinopropyltrimethoxysilane, n-butylaminopropyltrimethoxysilane, trimethoxysilylpropylethylenetriamine, (aminoethylaminomethyl)phenethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-(2 -aminoethyl)aminopropyl-1-rimethoxysilane, etc., but other water-soluble silane coupling agents may be used. Some silane coupling agents are poorly soluble in water, and can be completely dissolved by adding them to water whose pH has been adjusted in advance with a weak acid such as acetic acid or phosphoric acid.

In addition, suitable hydrolysis occurs with a weak acid, and it can be converted into a highly reactive silanol compound for use.

When a strong acid such as sulfuric acid, hydrochloric acid, or nitric acid is used to adjust the pH of the water in which the above-mentioned silane coupling agent is dissolved, the silane coupling agent is rapidly hydrolyzed, and the resulting silanol compounds mutually dehydrate. This is not preferable because it tends to cause condensation and bonding, generate water-insoluble siloxane oligomers, and cause precipitation, or gelation, which tends to make the aqueous solution non-uniform.

Regarding the ρ11 value of water that dissolves the above-mentioned silane coupling agent, the silane coupling agent is sufficiently hydrolyzed,
There is no problem as long as the pH value allows a uniform aqueous solution to be obtained. However, if the hydrolysis of the silane coupling agent is insufficient and the adhesion is poor, an organometallic catalyst such as dibutyltin diacetate or dibutyltin dilaurate may be used as necessary. It is also possible to add organic titanates such as , tetraisopropyl titanate, te-1-ra n-butyl titanate, and the like.

If an aqueous solution of a silane coupling agent is applied alone without adding a chelating agent to the surface of a steel material coated with the above-mentioned polytitanocarbosilane treatment agent, the silanol compound in the aqueous solution is too reactive. In a wet film obtained by applying an aqueous solution, an excessive condensation reaction occurs between silanol compounds, producing non-adhesive inert molecules such as siloxane oligomers, which are deactivated.

However, by using a chelating agent in combination, excessive condensation reaction between silanol compounds can be suppressed and deactivation can be prevented. That is, by applying the above-mentioned mixed treatment agent to the surface of the steel material coated with the above-mentioned polytitanocarbosilane treatment agent, the polytitanocarbosilane treatment can be performed without deactivating the silanol compound in the mixed treatment agent. Since it bonds with the agent layer through a condensation reaction and exhibits strong adhesive properties, corrosion resistance is significantly improved.

When preparing the mixed treatment agent mentioned in 2 above, the concentration of the silane coupling agent in the aqueous solution of the silane coupling agent and the concentration of the chelating agent in the aqueous solution of the chelating agent prepared in advance are arbitrary; Regarding the mixed processing agent obtained by mixing.

The final number of moles of the silane coupling agent contained in the mixed treatment agent IQ is 0.01 to 2.0 moles, and the ratio of the number of moles of the silane coupling agent to 1 mole of the silane coupling agent is 0.01 to 2.0 moles. It is desirable to set it to 0.5.

Regarding the concentration of the above-mentioned silane coupling agent, if the number of moles of the silane coupling agent contained in the above-mentioned mixed treatment agent IQ is 0.01 mol or less, the adhesiveness of the film obtained by applying the mixed treatment agent will be poor. On the other hand, if the amount exceeds 0.2 mole, the stability of the mixed treatment agent deteriorates, which is not preferable. Furthermore, if the ratio of the number of moles of the chelating agent to 1 mole of the silane coupling agent is less than 0.01, the effect of preventing the deactivation of the silane coupling agent will be small, and if it is more than 0.5, the adhesiveness will decrease and the corrosion resistance will be reduced. This is not desirable because it worsens the

The above-mentioned mixed treatment agent can be applied to the surface of the steel material coated with the above-mentioned polytitanocarbosilane treatment agent in an amount ranging from 10 to 11,000r (dry weight) and 7m. desirable. Regarding the amount of the mixed treatment agent attached, the amount of the mixed treatment agent attached is 10% as a dry weight.
mg/n? The adhesion improvement effect is small below 1
If it is more than 000 .mu./i, it will take a long time to develop adhesiveness, making it unsuitable for practical use.

Furthermore, the organic coating film used in the present invention will be explained. The organic coating film referred to in the present invention is a coating film made of an organic resin coating such as an epoxy resin coating, a phenol-epoxy resin coating, a fluororesin coating, a polyimide resin coating, and a polyphenyl sulfide resin coating.

Furthermore, if the organic coating film requires heat resistance or high strength, silica powder may be added to the above organic resin coating.
Inorganic fillers such as titanium oxide powder, glass powder, slag powder, mica powder, wollastonite powder, mapico powder, molybdenum trioxide powder, silicomolybdic acid powder, tungsten dioxide powder, silicotungstic acid powder, zinc chromate powder, etc. It is also possible to use one or a mixture of two or more reinforcing materials such as fibrous fillers such as glass fibers, slag fibers, carbon fibers, and ceramic fibers. Further, when weather resistance is required for the organic coating film, a weather resistance material such as carbon black, an inorganic pigment, or an organic pigment may be mixed with the above-mentioned organic resin coating.

A partial cross section of the coated steel material according to the present invention obtained as described above is as shown in Fig. 1. In Fig. 1, 1 indicates steel material from which scale has been removed by pickling or blasting, etc., and 2 indicates silica-based dispersion. 3 is a polytitanocarbosilane treatment agent layer, 4 is a mixed treatment agent layer containing a chromate agent and a silane coupling agent, and 5 is an organic coating film.

In addition, 2 in the figure is the total chromium weight of 50 to 1200 ■/
3 is the thickness of 0.1 to 50 μm, 4 is the amount of adhesion of 10 to 1000 μm/Po as dry weight, and 5 is the amount of adhesion of
Good results can be obtained if the thickness is O,OS~8rttn.

The present invention will be specifically explained below using Examples.

(Example) Example 1-0 A steel plate (75 x 150 x 6 mm) was degreased and subjected to grid-plast treatment, and a treatment agent of 210 mg/rrr (converted to total chromium adhesion amount) was applied to the surface of the steel plate (75 x 150 x 6 mm) at 190°C.
After heating and baking, a polytitanocarbosilane treatment agent was spray applied to a film thickness of 18 μm, baked and cured at 550°C by laser irradiation heating, and after cooling to 190°C by air cooling, the chelating agent was applied. A mixed treatment agent of
g/rrr with a spray nozzle, heated and cured at 210°C, then electrostatically applied epoxy resin powder coating to a film thickness of 350 μm and baked at 230°C according to the present invention. A painted steel plate (A) was created. that time,"
The Chrome-1 treatment agent, polytitanocarbosilane treatment agent, and mixed treatment agent of a chelating agent and a silane coupling agent were prepared in the following manner.

Chrome-I treatment agent: Polyvinyl alcohol was added to an aqueous solution in which 8% by weight of chromic anhydride was dissolved to reduce it, and the weight ratio of hexavalent chromium to total chromium was adjusted to 0.75.

Next, 5 g of fine silica powder was mixed and dispersed as a dispersant into this aqueous solution IQ, and then pyrogallol was added and further reduced to adjust the weight ratio of hexavalent chromium to total chromium to 0.65.

Polytitanocarbosilane treatment agent: 20% by weight polytitanocarbosilane (manufactured by Ube Industries, Ltd.)
An N-methylpyrrolidone solution was prepared and used as a polytitanocarbosilane treatment agent.

Mixed processing agent of chelating agent and silane coupling agent γ-anilinopropyltrimethoxysilane (SZ 6083 manufactured by Le Silicone Co., Ltd.
) was dissolved in distilled water adjusted to pl+2.5 with acetic acid to prepare an aqueous solution. Separately from the above aqueous solution, ethylenediaminetetraacetic acid was used as a chelating agent and dissolved in distilled water adjusted to pH 6 with ammonia water to prepare an aqueous solution.

The above γ-anilinopropyltrimethoxysilane aqueous solution and ethylenediaminetetraacetic acid aqueous solution were mixed together, and the number of moles of γ-anilinopropyltrimethoxysilane contained in the treatment agent IQ was 0.04 mol, and the ethylenediaminetetraacetic acid aqueous solution was Acetic acid was blended in an amount of 0.1 mol per 1 mol of the γ-anilinopropyltrimethoxysilane.

In addition, as a comparison material, instead of applying a mixed treatment agent of a chromate treatment agent, a polytitanocarbosilane treatment agent, a chelating agent and a silane coupling agent to the steel sheet surface in the same manner as the above-mentioned painted steel sheet (A), , an epoxy resin-coated steel sheet (B) corresponding to JP-A-59-115832 coated with only a chromate treatment agent, and an aqueous solution of γ-glycidoxypropyltrimethoxysilane with a dry coating weight of 260 μ/m2. An epoxy resin-coated steel plate (C) corresponding to that of JP-A-60-23038 was prepared.

For the above A-C epoxy resin coated steel plates, an adhesion test [substrate test; according to JIS K5400, the adhesion of the coating film to the steel material was evaluated from 0 to 10 (out of 10 points).
], water conduction immersion test (immersion temperature 95℃, immersion time 8
Table 1 shows the results of a boiling salt water immersion test (immersion temperature 95°C, immersion time 8000 hours, immersion liquid 3% NaCl, adhesive strength test after immersion). Indicated.

Table 1 The results in Table 1 indicate that there are significant differences in performance in terms of adhesive strength, water resistance at high temperatures, and salt water resistance. The epoxy resin-coated steel sheet (A) according to the present invention using a carbosilane treatment agent and a mixed treatment agent of a chelating agent and a silane coupling agent is the same as the epoxy resin-coated steel sheet (A) according to the present invention, which uses only a chromate treatment agent.
Compared to the epoxy resin-coated steel sheet (B) corresponding to Publication No. 1.15832 and the epoxy resin-coated steel sheet CC) corresponding to JP-A No. 60-23038 using only an aqueous solution of a silane coupling agent, It was confirmed that significantly superior results could be obtained.

Example 2 The above-mentioned epoxy resin-coated steel sheet (A) was prepared in the same manner as in Example 1, except that the type of dispersant mixed in the chromate treatment agent was changed as follows.

Dispersant; 1. Fine powder silica 2, colloidal silica 3, tetrae 1 to xysilane 4, additive-free The above epoxy resin coated steel sheets were subjected to the above adhesive force test, submerged water immersion test and boiling salt water immersion test, and the results of comparison are shown in Table 2. Indicated.

From the results in Table 2, it can be seen that in terms of adhesive strength, water resistance at high temperatures, and salt water resistance, performance deteriorates when no dispersant is added, but when a dispersant is added, Good results were obtained regardless of the type of dispersant, and it was confirmed that it was necessary to mix a dispersant into the processing agents of the present invention.

Example 3゜By the same method as in Example 1, the above-mentioned epoxy-coated steel sheet (A) was prepared by changing the type of silane coupling agent used in preparing a mixed treatment agent of a chelating agent and a silane coupling agent as follows.
It was created.

Silane coupling agent: 1, γ-anilinopropyltrimethoxysilane 2, n-
Butylaminopropyltrimethoxysilane 3, γ-glycidoxypropyltrimethoxysilane 4, trimethoxysilylpropyldiethylenetriamine 5, (aminoethylaminomethyl)phenethyltrimethoxysilane 6, γ-(2-aminoethyl)aminopropyl 1- Table 3 shows the results of the above-mentioned adhesion test, submerged water immersion test, and boiling salt water immersion test conducted on the epoxy-coated steel sheet (A) described in "Rimethoxysilane 7, No Additive".

From the results in Table 3, it can be seen that the performance of adhesive strength, high-temperature water resistance, and salt water resistance is significantly improved by adding a silane coupling agent. The excellent effect of the ring agent was confirmed.

Example 4゜The epoxy resin coated steel sheet (A) was prepared in the same manner as in Example 1 by changing the type of chelating agent used in preparing a mixed treatment agent of a chelating agent and a silane coupling agent as follows. .

Sharp tJtl: 1. Ethylenediaminetetraacetic acid 2, nitrilotriacetic acid 3, triethanolamine 4, additive-free The above-mentioned epoxy resin-coated steel sheets were subjected to the above-mentioned adhesive force test, water production immersion test, and boiling salt water immersion test, and the comparison results are shown in Table 4. It was shown to.

From the results shown in Table 4, the performance of adhesion, high-temperature water resistance, and salt water resistance was significantly improved by adding a chelating agent, and the silane coupling treatment agent according to the present invention It was confirmed that it was necessary to add a chelating agent.

Example 5 In the same manner as in Example 1, the following coated steel plates were prepared by spraying the following organic resin paint in liquid form instead of the epoxy resin powder paint.

Organic paint; 1. Phenol/epoxy resin paint 2,
Fluororesin paint 3, polyimide resin paint 4, polyphenylene sulfide resin paint 5, polyquinoxaline resin paint The above-mentioned coated steel sheets were subjected to the adhesion test, water production immersion test, and boiling salt water immersion test, and the results were compared in Section 5. Shown in the table.

Table 5 The results in Table 5 show that good results were obtained in terms of adhesion, high-temperature water resistance, and salt water resistance, regardless of the type of organic resin paint, and the coated steel sheet according to the present invention showed excellent effects. I was able to confirm.

(Effects of the Invention) As is clear from the examples, the coated steel according to the present invention has significantly improved adhesion between the steel and the organic coating, boiling water immersion resistance, and boiling salt water immersion resistance compared to conventional polyolefin-coated steel. This makes it possible to provide coated steel with unprecedented durability.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a painted steel material according to the present invention, and FIGS. 2 and 3 are partial cross-sectional views of painted steel materials according to a conventional method.・1. steel material 2, chromate treatment agent layer 3 containing a silica-based dispersant,
Polytitanocarbosilane treatment agent layer 4, mixed treatment agent layer 5 of chelating agent and silane coupling agent, organic coating 1 Figure 1: Steel material 2: Chromate column storage 3: Polytitanocarbosilane treatment agent Layer 4: Mixed treatment agent of chelating agent, silanka, and blinking agent Layer 5: Organic coating Figure 2 Figure 3

Claims (2)

[Claims] (1) A chromate treatment agent layer containing a silica-based dispersant, a polytitanocarbosilane treatment agent layer, a mixed treatment agent layer of a chelating agent and a silane coupling agent, and an organic coating film are sequentially laminated on the steel surface. Features painted steel. (2) The invention has an organic coating film made of an organic resin coating such as an epoxy resin coating, a phenol-epoxy resin coating, a fluororesin coating, a polyimide resin coating, or a polyphenylene sulfide resin coating. painted steel.