JPH04187798A - Metal surface treating agent and metal surface treating liquid - Google Patents

Abstract

PURPOSE:To obtain a metal surface treating agent for improving corrosion resistance without causing environmental pollution by allowing a specified compd. contg. an amino group to react with specified alpha,beta-unsatd. carboxylic acid and using the resulting reaction product as an effective component. CONSTITUTION:A compd. represented by a formula H2N-(CH2-CH2-NH)k-Z (where k is an integer of 1 or more, preferably about 500 or less and Z is -H or -CH2-CH2-OH) is allowed to react with a compd. represented by the right formula (where each of R<1> and R<2> is -H, -CH3, -COOH, -CH2COOH or phenyl) in 10.0-0.2 ratio of amine equiv. to acid equiv. at about 40-120 deg.C for about 1-5hr. The former compd. may be ethylenediamine or polyethyleneimine and the latter compd. may be acrylic acid or itaconic acid. A metal surface treating agent contg. the resulting reaction product as an effective component is dissolved or dispersed in water by about 0.01-5wt.% to obtain a metal surface treating liq. When a metal is dipped in the treating liq., a protective coat having superior corrosion resistance is formed on the surface of the metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a metal surface treatment agent and a metal surface treatment liquid for forming a protective film on a metal surface to improve corrosion resistance.

[Conventional technology]

The surface of metal materials used for automobile bodies, building materials, etc.
Easily exposed to corrosive environments. Therefore, by chemically treating the metal surface, a metal phosphate chemical conversion coating and/or a metal oxide coating is formed on the metal surface to improve its corrosion resistance.

The metal surface treated in this manner is rinsed with an aqueous solution containing a hexavalent chromium compound or subjected to post-treatment to further improve corrosion resistance.

However, surface treatment liquids containing hexavalent chromium compounds as active ingredients have problems such as the chromium compounds scattering in the form of mist during the treatment process, requiring a large amount of equipment costs for washing wastewater treatment equipment, etc. There were problems such as the danger of being a source of pollution due to elution of chromium compounds from the treated film.

Therefore, metal surface treatment agents that do not contain chromium compounds have been proposed. For example, JP-A-58-117879 discloses tartaric acid, oxybenzoic acid, etc. as metal surface treatment agents used after forming a phosphate film on the surface of galvanized steel sheets and zinc-containing alloy-plated steel sheets. ing.

On the other hand, although the rust prevention of automobile bodies has been considerably improved with the introduction of cationic electrodeposition paints, it has not yet reached a fully satisfactory level.

[Problem to be solved by the invention]

The metal surface treatment agent described in the above-mentioned publication is advantageous in that it does not contain chromium compounds, and can be used in the form of an aqueous solution, so it can be added to the first washing solution used in the water washing process after phosphate treatment, for example. However, the effect of improving corrosion resistance is insufficient.

Furthermore, since the corrosion resistance of the metal surface on which the cationic electrodeposited coating is formed depends on the performance of the phosphate chemical conversion coating, it is required to improve the characteristics of the phosphate chemical conversion coating.

Therefore, this invention overcomes the conventional problems and can be used as a substitute for hexavalent chromium compounds, and can improve the corrosion resistance of metal surfaces without causing pollution problems, especially for automobile bodies using cationic electrodeposition coating. The first objective is to provide a metal surface treatment agent that can significantly improve the corrosion resistance of metals. Furthermore, the present invention provides a metal surface treatment liquid that can be used in a water washing step after phosphate chemical conversion treatment, and can form a protective film that improves the corrosion resistance of the metal surface as described above. is the second issue.

[Means to solve the problem]

In order to solve the above first problem, the present invention provides the following-
Compound HJ-(CHt-C8--NH)k-Z shown in bottom (1)
-(1) [wherein k is an integer of 1 or more, Z is -H or -CH.

-C)k. -OR. ] and the compound represented by the following - bottom (2) [wherein R1
and R2 are each independently -H1-CH,, -COO
It is any one of H, -CH, COOH, and phenyl group. Provided is a metal surface treatment agent whose active ingredient is a reaction product obtained by reacting the following.

In order to solve the second problem, the present invention provides metal surface treatment using a compound obtained by reacting the compound represented by the above-mentioned bottom (1) and the compound represented by the above-mentioned bottom (2) as an active ingredient. To provide a metal surface treatment liquid in which an agent is dissolved or dispersed in water.

In the above equation 0, k is an integer of 1 or more, and if it is less than 1, sufficient performance cannot be obtained. Also preferably, k
is less than 5000. This is because if the molecular weight is too large, the viscosity is too high, which may cause problems in handling, or may adversely affect solubility and dispersibility in water. In the present invention, the amino group-containing compound represented by the above-mentioned bottom (1) and α shown by the above-mentioned bottom (2).

By reacting with β-unsaturated carboxylic acid, a Michael addition reaction as shown in the following formula 〇>N4 + CHz・
CH-COOH→ >N-CFI2-CH, -COOI
(...■ proceeds to give a β-alanine derivative. The synthesis of β-alanine derivatives by such a Michael addition reaction is described, for example, in the Journal of Organic Chemistry (Journal of Organic Chemistry).
Chemistry L. 94 (1958).

The amino group-containing compound represented by the above general formula 〇 is, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 2-(
(2-aminoethylamino) ethanol, polyethyleneimine, etc., which may be used alone or in combination of two or more.

Further, examples of the α,β-unsaturated carboxylic acid represented by the above-mentioned bottom (2) include acrylic acid, methacrylic acid, maleic acid, cinnamic acid, and itaconic acid.
Used alone or in combination of two or more.

When synthesizing the metal surface treatment agent of this invention, it is possible to use a solvent if necessary, and preferably one that serves as an auxiliary solvent during water solubilization or water dispersion (including emulsion) of the resulting treatment agent. ,,for example, methyl alcohol,
Water-compatible solvents such as alcohols such as ethyl alcohol and isopropanol; ketones such as acetone; and ethers such as dioxane can be used alone or in combination of two or more.

The reaction between the above amino group-containing compound and the α,β-unsaturated carboxylic acid for synthesizing the metal surface treatment agent of the present invention can be carried out, for example, by mixing the two and using the above-mentioned solvent. It is carried out for 1-5 hours at a temperature of 120 °C.

The ratio of the amino group-containing compound to the α,β-unsaturated carboxylic acid is, for example, amine equivalent of the reaction product/
It is preferable to set the acid equivalent to 10.0 to 0.2.

This is because, outside this range, the solubility and dispersibility in water and the precipitability on the object to be treated during metal surface treatment cannot be balanced, and there is a risk that sufficient performance may not be obtained.

The metal surface treatment agent of the present invention is used by being dissolved or dispersed in water (including being made into an emulsion). The concentration of the treatment agent is not particularly limited, but for example, 0.01
It is preferably set in a range of 5% by weight. Also,
The concentration may be kept high during transportation or storage, and then diluted with water or the like before use. When treating a metal surface, if the concentration of the treatment agent is less than 0.01% by weight, the treatment effect may not be obtained, and if it exceeds 5% by weight, the treatment effect will not improve and the coating film applied after the metal surface treatment will deteriorate. It may have a negative effect on the appearance. When the treatment agent is diluted with water, it may naturally become an emulsion, and this emulsion liquid is also the treatment liquid of the present invention.

The metal surface treatment liquid of the present invention has the metal surface treatment agent dissolved or dispersed in water, and is preferably used after adjusting the pH to about 2 to about 10. This is because if the pH is outside the above range, the metal surface will be heavily eroded during surface treatment, which will have a negative effect on corrosion resistance, but the pH value of the treatment liquid is not limited to the above range.

Note that the metal surface treatment agent of the present invention may be dissolved or dispersed in water (including making an emulsion), or the p.
In order to adjust H, an organic acid and/or an inorganic acid can be added as necessary. Examples of the acid used include phosphoric acid, sulfuric acid, acetic acid, and oxalic acid, which may be used alone or in combination of two or more.

In addition to the above-mentioned components, the metal surface treatment liquid of the present invention may contain other components as long as they do not impair the effects of the present invention.
For example, Ti-containing salts such as fluorotitanic acid,
Zr such as fluorofluorinated zirconium salt etc.
salts containing H, such as hexafluorohafnium salts, etc.
A salt containing f, tannic acid, etc. may be added.

The objects to be treated with the metal surface treatment liquid of this invention are:
There is no particular limitation as long as it is a metal material, for example, steel plate,
These include galvanized steel sheets, zinc-containing alloy-plated steel sheets, aluminum steel sheets, and those whose surfaces have been subjected to phosphate chemical conversion treatment.

After the metal surface has been subjected to phosphate chemical conversion treatment such as zinc phosphate, it is directly immersed in the metal surface treatment liquid of the present invention and/or sprayed with the same treatment liquid. In the case of immersion, the immersion time is, for example, 10 seconds to 2 minutes, and in the case of spraying, the immersion time is, for example, 10 seconds to 1 minute at a normal spray flow rate, but is not limited to these times. It is possible to use the treatment liquid as the first washing liquid in the water washing step after the phosphate chemical conversion treatment.

After being treated with the metal surface treatment liquid of the present invention, for example, if necessary, the metal surface is washed with water and then painted.

Coating methods include, for example, brush coating, spray coating, electrostatic coating, dipping coating, roller coating, and electrodeposition coating, but the best results are particularly obtained when coating is performed by cationic electrodeposition coating. This is because in cationic electrodeposition coating, when the electrodeposition paint adhered to the metal surface is baked and dried to obtain the desired coating film, the blocked isocyanate curing agent, melamine curing agent, etc. in the cationic electrodeposition paint components are removed. Functional groups contained in the metal surface treatment agent (for example, -0H1-
It is thought that the adhesive reacts with active hydrogen-containing functional groups such as COOH, -NH-1-NH, etc., and crosslinks with each other, thereby improving the adhesion of the coating film and improving the corrosion resistance.

By washing with water after treatment with the metal surface treatment liquid of the present invention and before painting, it is possible to prevent contaminant ions from being carried into a paint bath such as an electrodeposition paint bath.

In the above explanation, it has been assumed that the metal surface treatment agent of the present invention can be used as a pretreatment for painting, especially cationic electrodeposition coating. It can also be used as

[For production]

The metal surface treatment agent according to the present invention has a β-alanine structure and exhibits chelate-forming ability.

That is, in the treatment liquid, the carboxyl group and amino group (which may be primary, secondary, or tertiary) of this compound form a chelate with the metal ion.

For example, when a steel plate subjected to zinc phosphate treatment is brought into contact with the treatment solution according to the present invention, Fe'' and Z ng
Metal ions such as * are eluted, and then the β-alanine structure of the metal surface treatment agent is coordinated to these, forming an insoluble complex that precipitates on the metal surface as a substrate to form a film.

The ability of the specific metal surface treatment agent to chelate metal ions is thought to be based on the action of the carboxyl group and amino group forming the β-alanine structure.

Furthermore, the improvement in the adhesion of the metal surface treatment agent of the present invention to the cationic electrodeposited coating film can be achieved by functional groups contained in the metal surface treatment agent (for example, -0H1-COOHl-NH-1-NH,
This is thought to be due to the reaction between the functional group (having active hydrogen such as

〔Example〕

Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples.

Example 1- 10.4 g of 2-(2-aminoethylamino)ethanol
(0.1 mol) was dissolved in methanol 10, and while stirring at room temperature, 7.2 g (0.1 mol) of acrylic acid was dissolved in about 1 mol of methanol.
It was dripped slowly over 0 minutes.

After heating the resulting solution under reflux at a temperature of 70°C for 3 hours,
'H-NMR measurement of the reaction product was performed, and the absorption of protons of the vinyl group of acrylic acid (5.27 to 6.02 ppm) was determined.
After confirming the disappearance of , the reaction was terminated. What is the amine equivalent of the reaction product? , 8 meq/g, and the acid equivalent was 3.9 meq/g.

Example 2 - 10.3 g (0.1 mol) of diethylenetriamine was used instead of 2-(2-aminoethylamino)ethanol and 14.4 g (0.2 mol) of acrylic acid was used. The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 9.2
meq/g, and the acid equivalent was 6°1 meq/g. Example 3 - 14.6 g (0.1 mol) of triethylenetetramine was substituted for 2-(2-aminoethylamino)ethanol. The reaction was carried out under the same conditions as in Example 1, except that 14.4 g (0.2 mol) of acrylic acid was used, and a Michael reaction product was obtained. The amine equivalent of the reaction product is 10.
8 meq/g, and the acid equivalent was 5.4 meq/g.

Example 4 - 18.9 g (0°1 mol) of tetraethylenepentamine was used instead of 2-(2-aminoethylamino)ethanol and 14.4 g (0.2 mol) of acrylic acid was used. Except for this, the reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 12
．． 1 l1leq/g, and the acid equivalent is 4.9 w+e
q/g.

Example 5 - 10.3 g (0.1 mol) of diethylenetriamine was used instead of 2-(2-aminoethylamino)ethanol and 7.2 g (0.1 mol) of acrylic acid was used. The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 11.8
meq/g, and the acid equivalent was 3°9 meq/g.

Example 6 - 10.4 g of 2-(2-aminoethylamino)ethanol
(0.1 mol) and 11.6 g (0.1 mol) of maleic acid was used instead of acrylic acid.
The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 6.7 meq/g
and the acid equivalent was 6.7 meq/g. Example 7 - 10.4 g of 2-(2-aminoethylamino)ethanol
(0.1 mol) was used, except that 13.0 g (0.1 mol) of itaconic acid was used instead of acrylic acid.
The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 6.4 meq/g
The acid equivalent was 6.4 meq/g.

Example 8 - 18.0 g (0.01 mol) of polyethyleneimine with an average molecular weight of 1800 (trade name "Evomin 5P-018J" manufactured by Nippon Shokubai Chemical Co., Ltd.) instead of 2-(2-aminoethylamino)ethanol ) and using 14.4 g (0.2 mol) of acrylic acid, the reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product.The amine equivalent of the reaction product was 8. .6 meq/
g, and the acid equivalent was 5.7 meq/g.

Example 9 The product obtained in Example 1 was diluted with deionized water to make an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 5.1 with a 10% by weight aqueous phosphoric acid solution to prepare a solution for metal surfaces. A treatment solution was obtained.

Example 10 The product obtained in Example 2 was diluted with deionized water to make an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 3.5 with a 10M aqueous phosphoric acid solution. A treatment solution was obtained.

Example 11 The product obtained in Example 3 was diluted with deionized water to obtain an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 5.0 with a 10% by weight aqueous phosphoric acid solution to treat metal surfaces. I got the liquid.

Example 12 The product obtained in Example 4 was diluted with deionized water to make an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 4.5 with a 10% aqueous phosphoric acid solution. A treatment solution was obtained.

Example 13 The product obtained in Example 5 was diluted with deionized water to make an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 6.2 with a 10% by weight aqueous phosphoric acid solution to treat metal surfaces. I got the liquid.

Example 14 The product obtained in Example 6 was diluted with deionized water to make an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 8.2 with a 10% by weight aqueous phosphoric acid solution. A treatment solution was obtained.

Example 15 The product obtained in Example 7 was diluted with deionized water to obtain an aqueous solution with a concentration of 0.5 M%, and the pH was adjusted to 9.0 with a 10% by weight aqueous phosphoric acid solution. A processing solution was obtained.

Example 16 - The product obtained in Example 8 was diluted with deionized water to give an aqueous solution with a concentration of 0.5% by weight, adjusted to pH 9.2 with a 10% by weight aqueous phosphoric acid solution, and prepared on a metal surface. A processing solution was obtained.

Example 17 - A metal surface treatment liquid was prepared in the same manner as in Example 9, except that the amount of the reaction product (the amount of nonvolatile content) was 5.0% by weight.

Examples 18 to 26 - Examples 9 to 17 are zinc phosphate treated steel sheets obtained by chemically converting cold rolled steel sheets with a zinc phosphate treatment agent (manufactured by Nippon Paint Co., Ltd., No. Fugain 5D-2500 (trade name)). After immersing it in each metal surface treatment solution for 40 seconds at room temperature, washing it with deionized water and applying an epoxy cationic electrodeposition paint (Power Top T, '-1000 (product name) manufactured by Nippon Paint Co., Ltd.). After electrodeposition coating, air drying, and baking at 180° C. for 20 minutes, a coated metal plate test piece was obtained. The thickness of the electrodeposition coating film was 20 μm.

Comparative Example 1-2- (2-Aminoethylamino) Except that 7.3 g (0.1 mol) of butylamine was used instead of ethanol and 7.2 g (0.1 mol) of acrylic acid was used. The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 4.5 meq/
ε, and the acid equivalent was 4.5 meq/g.

Comparative Example 2 ~ Except that 18.5 g (0.1 mol) of monolaurylamine was used instead of 2-(2-aminoethylamino)ethanol and 7.2 g (0.1 mol) of acrylic acid was used. The reaction was carried out under the same conditions as in Example 1 to obtain a Michael reaction product. The amine equivalent of the reaction product is 3.0 me
q/g, and the acid equivalent is 3. It was Omeq/g.

Comparative Example 3 - The product obtained in Comparative Example 1 was diluted with deionized water to give an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 5.7 with a 10% by weight aqueous phosphoric acid solution to prepare a solution for metal surfaces. A treatment solution was obtained.

Comparative Example 4 - The product obtained in Comparative Example 2 was diluted with deionized water to form an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 4°0 with a 1.10% by weight phosphoric acid aqueous solution to prepare a solution for metal surfaces. A treatment solution was obtained.

Comparative Example 5 - 5.0 g (0,033 mol) of tartaric acid was diluted with deionized water to form an aqueous solution with a concentration of 0.5% by weight, and the pH was adjusted to 4.2 with a 10% by weight aqueous phosphoric acid solution. A surface treatment liquid was obtained.

Comparative Example 6 - Oxybenzoic acid 5. Og (0,036 mol) was diluted with deionized water to make an aqueous solution with a concentration of 0.5 ffi%,
The pH was adjusted to 4.0 with a 10ffi aqueous solution of phosphoric acid to obtain a metal surface treatment solution.

Comparative Example 7 - A test piece of a coated metal plate was obtained under the same conditions as in Example 18, except that a zinc phosphate-treated steel plate was electrodeposited without any post-treatment. .

Comparative Examples 8 to li - The above zinc phosphate treated steel sheets were immersed in each of the metal surface treatment solutions of Comparative Examples 3 to 6 for 40 seconds at room temperature, washed with deionized water, and coated with epoxy cationic electrodeposition. 1 (Power Top U-10 manufactured by F1 Hon Paint Co., Ltd. (1 < commercial city name))
was electrodeposited, air-dried, and baked at 18θ1 for 20 minutes to obtain a coated metal plate test piece. The thickness of the electrodeposited coating was 20 μm. A cross cut was made in the coating of the 4° C1 test piece, and then the corrosion resistance of the electrodeposition coating was evaluated. The results are shown in Table 1. Table 1 also shows the pH of the treatment solution and the amount of non-volatile treatment agent.

Corrosion resistance was investigated by salt water immersion test and No. cycle test.

The salt water immersion test was conducted by measuring the tape peeling width from the cant portion after 480 hours of immersion in 5% by weight salt water at 55°C, and was evaluated using the following evaluation method.

0: Owa or more, 3 days or less △: Greater than 3fi, 6 cranes or less
%) -? It was performed by measuring the rust width from the cut part after 8 cycles of 1-5 cycles of drying (1 to 5 cycles at 55°C), and using the following evaluation method. Indicated.

○; On or more and 3w or less △: Larger than 3D, 6I1m or less x -61 As shown in Table 1, the test pieces post-treated with the metal surface treatment liquid of the example were more effective than those of the comparative example. Excellent corrosion resistance.

〔Effect of the invention〕

Since the metal surface treatment agent according to the present invention contains the above-mentioned specific compound as an active ingredient, when metal surfaces are treated using this agent, corrosion resistance is improved compared to conventional agents. In particular, when used in pretreatment for cationic electrodeposition coating, corrosion resistance and paint adhesion properties can be improved.

The metal surface treatment liquid according to the present invention contains a treatment agent containing the specific compound listed in 1-1 as an active ingredient, so by treating the metal surface with this, a protective film is formed on the fully curved surface and corrosion resistance is improved. improves. This protective film has particularly excellent adhesion properties with cationic electrodeposition coatings.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Claims] 1 Compound H_2N-(CH_2-CH_2-NH)_k-Z... represented by the following general formula (1)
-(1) [In the formula, k is an integer of 1 or more, and Z is -H or -CH_2-CH_2-OH. ] and compounds represented by the following general formula (2) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ [In the formula, R^1 and R^2 are each independently -H, -
CH_2, -COOH) -CH_2COOH, and
Any of the phenyl groups. ] A metal surface treatment agent whose active ingredient is a reaction product obtained by reacting. 2 The ratio of amine equivalent/acid equivalent of the reaction product is 10.0
The metal surface treatment agent according to claim 1, which has a molecular weight of 0.2 to 0.2. 3. A metal surface treatment liquid comprising the metal surface treatment agent according to claim 1 or 2 dissolved or dispersed in water.