WO2013011790A1 - Aqueous composition for metal surface treatment, method for metal surface treatment using composition, and method for producing metal material having film, as well as metal surface treatment film using same - Google Patents

Abstract

[Problem] To provide means for dramatically improving Bi precipitation and preventing deterioration of metal film appearance in the form of fisheyes, dimples, and the like. [Solution] An aqueous composition for metal surface treatment is characterized in being an aqueous composition for metal surface treatment containing a cationic resin emulsion, wherein the dispersoid of the cationic resin emulsion comprises an amino compound of a modified epoxy resin, a block polyisocyanate, and a tin compound represented by formula 1 (1) (where in formula 1, m is 4 or greater and n is between 0 and 10), and the dispersion medium of the cationic resin emulsion contains Bi ions.

Description

Aqueous composition for metal surface treatment, metal surface treatment method using the same, method for producing metal material with film, and metal surface treatment film using these

The present invention relates to an aqueous composition for metal surface treatment capable of forming a film capable of imparting excellent corrosion resistance and coating appearance to a metal material, particularly a metal structure having a complicated shape, and a metal using the same. The present invention relates to a surface treatment method, a method for producing a metal material with a coating, and a metal surface treatment coating using these.

Conventionally, electrodeposition coating having high throwing power has been generally used as a method for imparting excellent corrosion resistance to various metal materials, particularly metal structures having complicated shapes. However, in many cases, the desired corrosion resistance cannot be obtained only with the electrodeposition coating film obtained by electrodeposition coating. Processing was applied.

Electrodeposition coating consists of an anionic electrodeposition coating in which a coating is deposited by anodic electrolysis in an aqueous paint containing an anionic resin emulsion, and an aqueous coating containing a cationic resin emulsion. Cathodic electrolysis can be broadly divided into cationic electrodeposition coating in which a coating film is deposited. To improve the corrosion resistance of ferrous metal materials, cationic electrolysis, which does not cause the base metal to elute into the paint during electrolytic treatment, is possible. Electrodeposition coating is advantageous, and cationic electrodeposition coating is widely applied to automobile bodies, automobile parts, home appliances, building materials, etc., which are metal components mainly composed of iron-based materials.

Cation electrodeposition coating has a long history in the market, and once it was rust-proof by blending chromium and lead compounds. However, since this also has insufficient rust prevention properties, a ground treatment such as a zinc phosphate chemical conversion treatment was essential. Currently, chromium and lead compounds have become virtually unusable due to environmental regulations, especially the European ELV regulations, so alternative components have been studied and their effects have been found in bismuth compounds. Is disclosed.

Patent Document 1 (Japanese Patent Application Laid-Open No. 5-32919) discloses a resin composition for electrodeposition paints containing at least one pigment coated with a bismuth compound.

Patent Document 2 (WO 99/31187) discloses a cationic electrodeposition coating composition comprising an aqueous dispersion paste containing an aqueous dispersion in which an organic acid-modified bismuth compound is present in a water-insoluble form. ing.

Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-137367) discloses a cationic electrodeposition coating characterized by comprising a colloidal bismuth metal and a resin composition having a sulfonium group and a propargyl group.

Patent Document 4 (Japanese Patent Application Laid-Open No. 2007-197688) discloses an electrodeposition coating comprising particles of at least one metal compound selected from bismuth hydroxide, a zirconium compound and a tungsten compound, wherein the metal compound is 1 to An electrodeposition paint characterized by being 1000 nm is disclosed.

Patent Document 5 (Japanese Patent Laid-Open No. 11-80621) discloses a cationic electrodeposition coating composition characterized by containing an aqueous solution of an aliphatic alkoxycarboxylic acid bismuth salt.

Patent Document 6 (Japanese Patent Laid-Open No. 11-80622) contains an aqueous solution of bismuth salt with two or more organic acids, wherein at least one of the organic acids is an aliphatic hydroxycarboxylic acid. A cationic electrodeposition coating composition characterized by the above is disclosed.

Patent Document 7 (Japanese Patent Laid-Open No. 11-100533) discloses a cationic electrodeposition coating composition characterized by containing bismuth lactate using lactic acid containing 80% or more of L isomers among optical isomers. Has been.

Patent Document 8 (Japanese Patent Laid-Open No. 11-106687) includes an aqueous solution of an organic acid bismuth salt containing two or more organic acids, wherein at least one of the organic acids is an aliphatic alkoxycarboxylic acid. A cationic electrodeposition coating composition characterized by the above is disclosed.

These patent documents can be roughly classified into Patent Documents 1 to 4 and Patent Documents 5 to 8. That is, Patent Documents 1 to 4 are those in which a bismuth compound or metal bismuth insoluble in an aqueous paint is dispersed, and Patent Documents 5 to 8 dissolve at least the bismuth compound until there is no remaining solids, that is, Bi. It is characterized by being added to the paint after being in an ionic state.

However, the bismuth compounds in these patent documents only act as substitutes for chromium compounds and lead compounds, and sufficient corrosion resistance cannot be obtained without a base treatment such as a zinc phosphate chemical conversion treatment. In fact, these patent documents disclose only examples based on the combination with zinc phosphate chemical conversion treatment.

On the other hand, recently, a technique that can further improve the corrosion resistance by a method other than a bismuth compound and can ensure sufficient corrosion resistance with one coat without applying a ground treatment such as a zinc phosphate chemical conversion treatment has been studied.

For example, Patent Document 9 (Japanese Patent Application Laid-Open No. 2008-274392) discloses a method of forming a film by coating a metal base material with a film forming agent in at least two stages of multi-stage energization methods, and (i) a film forming agent Is at least one selected from a zirconium compound and, optionally, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, aluminum, bismuth, yttrium, lanthanoid metal, alkali metal and alkaline earth metal A compound containing metal (a) comprising 30 to 20,000 ppm in terms of total metal (in terms of mass) and 1 to 40% by mass of a resin component, and (ii) a first stage using a metal substrate as a cathode Is applied by energizing for 10 to 360 seconds at a voltage (V1) of 1 to 50 V, and then 2 with a metal substrate as a cathode. A surface characterized in that the coating after the first is performed by energizing for 60 to 600 seconds at a voltage (V2) of 50 to 400 V, and (iii) the difference between the voltage (V2) and the voltage (V1) is at least 10 V A method of forming a treatment film is disclosed.

Patent Document 10 (Japanese Patent Application Laid-Open No. 2008-538383) discloses an aqueous coating composition containing (A) a rare earth metal compound, (B) a base resin having a cationic group, and (C) a curing agent, The coating material is immersed in an aqueous coating composition in which the amount of (A) rare earth metal compound contained in the coating composition is 0.05 to 10% by weight in terms of the rare earth metal relative to the solid content of the coating. A dipping step, applying a voltage of less than 50 V as the cathode in the aqueous coating composition, and a pretreatment step, and applying a voltage of 50 to 450 V as the cathode in the aqueous coating composition. A method for forming a multilayer coating film including an electrodeposition coating step in which a voltage is applied is disclosed.

Patent Document 11 (Japanese Patent Laid-Open No. 2010-24471) discloses that a bismuth compound is obtained by immersing a metal substrate in an aqueous solution containing an organic acid salt or inorganic acid salt of bismuth and electrolyzing the metal substrate as a cathode as a first step. A multilayer coating film forming method is disclosed in which a coating film is formed and an electrodeposition coating film is formed on the coating film by cationic electrodeposition coating as a second step.

A treatment liquid composition applied on the base treatment such as zinc phosphate-based chemical conversion treatment described in Patent Documents 1 to 8 is sufficient without the base treatment such as zinc phosphate-based chemical conversion treatment described in Patent Documents 9 to 11. The treatment liquid composition that can ensure corrosion resistance contains a catalyst for accelerating the crosslinking and curing reaction of aqueous resin as a common technique, and has contributed to the improvement of the crosslinking density and the lowering of the curing temperature. .

As the catalyst, lead compounds and tin compounds are generally used. Among them, in recent years, the use of tin compounds is common due to the toxicity of lead compounds, and compounds that can be expected to have a catalytic effect can also be used in combination, as in the present invention and Patent Document 9.

The contained tin compounds can be roughly divided into two types.

Examples of Patent Documents 1, 4, 9, and 11 and Patent Documents 12 to 14 show the use of solid tin compounds.

Examples of Patent Documents 5 to 8 and Patent Documents 15 to 17 show the use of liquid tin compounds.

Examples of solid tin compounds include use of dibutyltin oxide, dioctyltin oxide, monobutyltin oxide, monooctyltin oxide, and the like.

Examples of the liquid tin compound include dibutyltin diacetate, alkyltin aromatic carboxylic acid ester, alkyltin fatty acid salt, and alkyltin (alkyl mercaptan).

Japanese Patent Laid-Open No. 5-32919 WO99 / 31187 JP 2004-137367 A JP 2007-197688 A Japanese Patent Laid-Open No. 11-80621 Japanese Patent Laid-Open No. 11-80622 Japanese Patent Application Laid-Open No. 11-100533 Japanese Patent Laid-Open No. 11-106687 JP 2008-274392 A JP 2008-538383 A JP 2010-24471 A Japanese Patent Laid-Open No. 5-65438 JP 2008-231142 A JP 2004-269582 A Japanese Patent Publication No. 61-9986 JP-A-5-65439 JP 2004-123942 A

As a result of various studies on these conventional techniques, the present inventors have formed a coating that gives sufficient corrosion resistance on one metal without pretreatment such as a zinc phosphate-based chemical conversion coating on a metal material. A conclusion was reached that the application of Bi was most effective. And we decided to reconsider the effect of Bi.

And, as a function and effect of Bi, the function of the resin as a curing catalyst and the anticorrosion action of the base metal have been attracting attention, but the conventional technology can hope for some function as the curing catalyst, but the anticorrosion of the base metal. The action was extremely inadequate, and it was studied that maximizing this action would solve the problem.

The anticorrosive action of the base metal must be on the surface where Bi contacts with the metal, that is, the interface between the base metal surface and the coating, but in the prior art, the Bi component is uniformly dispersed in the coating and exhibits corrosion resistance. It was estimated that sufficient Bi was not previously present on the surface of the base metal.

Then, the present inventors reduced and precipitated Bi by low-voltage cathode electrolysis in the same bath, and then, at the stage where the diffusion of Bi ions became insufficient by high-voltage cathode electrolysis, this pH increase caused the cationic resin. It was confirmed that the reaction mechanism of precipitation was optimal.

Specifically, it is confirmed that the coating obtained by this can sufficiently improve the corrosion resistance of the base metal by Bi present at a high concentration on the surface of the base metal as well as the curing catalyst ability of the resin of Bi. did.

However, the conventional method has the following problems. As described above, in this method (multistage electrolysis method), first, Bi is reduced and deposited by low-voltage cathode electrolysis, and then a step in which a cationic resin is deposited is taken. Here, improving the Bi precipitation property leads to obtaining a Bi precipitation amount sufficient to obtain the necessary corrosion resistance at an early stage, which shortens the time required for the low voltage processing state, that is, improves the productivity and costs. It is possible to reduce. Therefore, this invention makes it the 1st subject to provide the means which improves the precipitation nature of Bi dramatically. Furthermore, in this system (multi-stage electrolysis system), the appearance of the coating film such as repellency and irregularity may deteriorate depending on conditions and the like. Therefore, this invention makes it a 2nd subject to provide the means which prevents the coating-film external appearance deterioration, such as a repellency and a flaw.

The present inventors have verified various cationic resins, curing agents, and curing catalysts, and verified combinations that can achieve the first and second problems. As a result, the present inventors adopted a cationic emulsion as a composition, and dispersed a specific cationic resin / curing agent / curing catalyst combination in the emulsion while bismuth ions were present in the dispersion medium of the emulsion. It has been found that the above-mentioned problems can be achieved by selecting as a quality component, and the present invention has been completed. Specifically, the present inventions are the following inventions (1) to (10).

The present invention (1)
An aqueous composition for metal surface treatment containing a cationic resin emulsion, wherein the dispersoid of the cationic resin emulsion is an aminated product of a modified epoxy resin (particularly a bisphenol type is preferred), a block polyisocyanate, and a formula 1:

(Wherein, in Formula 1, m is 4 or more, n is 0 or more and 10 or less), and the dispersion medium of the cationic resin emulsion contains Bi ions. This is an aqueous composition for surface treatment. In addition, you may contain a pigment particle as needed. Further, the dispersoid of the emulsion may contain a resin other than the aminated product of the modified epoxy resin (for example, other cationic resin or nonionic resin).

The present invention (2) is the aqueous composition for metal surface treatment according to the invention (1), wherein m in Formula 1 is 7 or more.

The present invention (3) is the aqueous composition for metal surface treatment according to the invention (1) or (2), wherein m in the formula 1 is 7.

The present invention (4) is the aqueous composition for metal surface treatment according to the invention (3), wherein m in the formula 1 is 7 and n is 0.

The present invention (5) is characterized in that the content of the tin compound in the total composition is 0.01 to 1% by weight as the Sn amount, according to any one of the inventions (1) to (4), It is an aqueous composition for metal surface treatment.

The present invention (6) is the aqueous composition for metal surface treatment according to any one of the inventions (1) to (5), characterized in that the composition is used for a multistage energization method in the same bath. is there.

According to the present invention (7), a metal material is coated in an electrolytic treatment process using the metal material to be treated as a cathode by immersing the metal material to be treated in any one of the aqueous compositions of the inventions (1) to (6). It is a metal surface treatment method characterized by depositing.

In the present invention (8), in the electrolytic treatment step, the metal material whose surface is cleaned is immersed in the aqueous composition according to any one of the inventions (1) to (6), or is immersed. However, the first step of electrolysis for 10 to 120 seconds at a voltage of 15 V or less, and the electrolysis for 30 to 300 seconds at a voltage of 50 to 400 V, was carried out in the same bath following the first step. A metal surface treatment method according to the invention (7), further comprising: a second step.

The present invention (9) is a process for producing a coated metal material characterized by having the electrolytic treatment step of the invention (7) or (8).

The present invention (10) is a film obtained by the production method of the invention (9), wherein metal Bi and oxidized Bi are deposited as Bi in an amount of 20 to 250 mg / m ² and the total film thickness is 5 to 40 μm. Further, the metal is characterized in that the Bi adhesion amount on the metal material side from the center of the film thickness: B is a Bi adhesion distribution in which the total Bi adhesion amount is 55% or more (B / A ≧ 55%) with respect to A. It is a surface treatment film.

FIG. 1 is a diagram showing the relationship between the amount of Bi deposition and the application time when a constant voltage is applied to the aqueous compositions according to Examples and Comparative Examples. FIG. 2 is a diagram showing a B / A profile when the aqueous composition according to Example 1 is used.

≪Metal surface treatment method≫
(Applicable)
The aqueous composition for metal surface treatment according to the present invention is used for the purpose of preventing various metals from corrosion. The metal material is not particularly limited, but steel materials such as cold-rolled steel plates, hot-rolled steel plates, cast materials, steel pipes, etc., and zinc-based plating treatment and / or aluminum-based plating are performed on those steel materials. Materials, aluminum alloy plates, aluminum castings, magnesium alloy plates, magnesium castings, and the like. It is particularly suitable for use in metal structures having complicated shapes, for example, automobile bodies, automobile parts, home appliances, building materials, etc., which are metal structures mainly composed of iron-based materials.

(Metal surface treatment method)
The metal surface treatment method according to the present invention includes a step of depositing a film on the surface of the metal material in an electrolytic treatment step using the above-described aqueous composition for metal surface treatment and using the metal material to be treated as a cathode. More preferably, the metal surface treatment method according to the present invention is performed after the electrolytic treatment step, and an electrolytic treatment step of performing electrolytic treatment on the metal material whose surface is cleaned in order to deposit a film on the metallic material. Including washing and baking processes. Hereinafter, the electrolytic treatment process and baking process characteristic of this method will be described in detail.

<Electrolytic treatment process>
This electrolytic treatment step (cathodic electrolysis) includes a first step of electrolysis for 10 to 120 seconds at a voltage of 15 V or less in a state where the metal material is immersed in an aqueous composition for metal surface treatment, and an aqueous solution for metal surface treatment. A second step carried out after the first step, in which the metal material is immersed in the composition and electrolyzed at a voltage of 50 to 400 V for 30 to 300 seconds, wherein the second step Is carried out in the same bath following the first step.

Here, the first step is a step mainly performed for preferentially attaching Bi, and the second step is a step mainly performed for preferentially depositing the cationic resin. In order to obtain sufficient corrosion resistance, it is necessary to have Bi that is in direct contact with the metal material, that is, the interface Bi that exists at the interface between the metal material and the coating. For this purpose, the order of the first step and the second step is required. And conditions are extremely important.

The voltage in the first step is 15 V or less (the lower limit is not particularly limited, but 0.01 V, for example), and electrolysis is preferably performed for 10 to 120 seconds. When the voltage is lower than 0 V, that is, when electrolysis is performed using a metal material as an anode, the metal material is eluted into the composition, not only reducing the stability of the composition, but also having an interface Bi necessary for improving the corrosion resistance. It will not adhere enough. Even when the upper limit is exceeded, resin deposition starts before Bi is preferentially deposited on the metal surface, so that sufficient corrosion resistance cannot be obtained.

When the treatment time is less than the lower limit, sufficient interface Bi is not deposited, and when it exceeds the upper limit, the adhesion amount of the interface Bi becomes excessive, and the adhesion of the film may be impaired.

The voltage in the second step is 50 to 400 V, and electrolysis is preferably performed for 30 to 300 seconds. When the voltage is lower than the lower limit, the amount of the resin film deposited is insufficient. When the voltage is higher than the upper limit, the resin film is excessively deposited, which is economically disadvantageous, and the finished appearance of the film may be impaired.

When shifting from the first step to the second step, there is no need to increase the voltage instantaneously, and even if it is increased slowly, the effect of the present invention is not impaired. In addition, the voltage need not always be constant in both the first step and the second step.

<Baking process>
Next, the baking process will be described. The baking method is not particularly limited, and examples thereof include a baking method in an oven. The baking temperature is, for example, 100 ° C. to 200 ° C. Further, although the baking time depends on the shape, size and material of the metal material to be treated, it is usually 10 to 30 minutes.

Next, the aqueous composition for metal surface treatment according to the present invention will be described in detail.

<< Aqueous composition for metal surface treatment >>
An aqueous composition for metal surface treatment according to the present invention is an aqueous composition for metal surface treatment containing a cationic resin emulsion, wherein the dispersoid of the cationic resin emulsion is an aminated product of a modified epoxy resin as a base resin, A blocked polyisocyanate as a curing agent and a tin compound having a specific structure as a curing catalyst (or as a co-catalyst) are essential, and the dispersion medium of the cationic resin emulsion contains Bi ions (for example, It corresponds to F2 agent used as an electrodeposition paint). Here, in the aqueous composition for metal surface treatment according to the present invention, for example, a pigment component can be arbitrarily blended. In this case, this pigment component corresponds to, for example, an F1 agent used as an electrodeposition paint. Hereinafter, each component will be described in detail.

<Composition component: Dispersoid of cationic resin emulsion>
(Composition component: Dispersoid of cationic resin emulsion / cationic resin)
* Ingredient The base resin according to the present invention essentially contains a base resin of a modified epoxy resin that is cationized with an amine as a cationic resin. Here, among the aminated products of modified epoxy resins, bisphenol type and novolac type modified epoxy resins are preferred, and bisphenol type is most preferred. The reason for using the modified component is as follows. Usually, when only these base resin components are used, the performance of the obtained film is not satisfied. Therefore, a method of adding and modifying a compound having a structure different from that of the base resin is employed. As an example, when a bisphenol A type epoxy resin that is not modified is used, the rigidity is very rich, but conversely, it lacks flexibility and sufficient performance cannot be obtained. Specifically, a film having both hardness and softness can be obtained by adding a polyol compound (detailed later) and the like.

Here, in order to impart cationicity to the resin, typically, a method of introducing an amino group into the resin skeleton (especially the terminal) (for example, in an epoxy resin, an amino group-containing compound is added to the terminal glycidyl group). Method). This will be described in detail later.

Hereinafter, an aminated product of a modified bisphenol type epoxy resin that is particularly suitable as a cationic resin will be described in detail. Here, a particularly preferred aminated product of a modified bisphenol A type epoxy resin is a modified resin, an epoxy resin having an epoxy equivalent of 180 to 2500, a primary and / or secondary amino group-containing compound, or bisphenol A as a raw material. It is an aminated product of a modified epoxy resin obtained by reacting them. Hereinafter, each component will be described.

* Raw material of modified epoxy resin of bisphenol A type First, a polyol compound is usually used as the modified resin. These are applied for the purpose of improving the plasticity of the epoxy resin. Specific examples thereof include polyol resins such as polyester polyol, polyether polyol, polyurethane polyol, and acrylic polyol, and aromatic condensed compounds having a hydroxyl group by adding phenol to the terminal. More specifically, polycaprolactone diol, polyethylene glycol, polypropylene glycol, xylene formaldehyde resin having a phenolic hydroxyl group and the like can be mentioned. The modification with these compounds is a technique that has been used conventionally since the hydroxyl groups of these compounds and the glycidyl ether portion of the epoxy resin can easily react. In the modified epoxy resin, these modified resins are contained in an amount of 5 to 30% by weight.

Next, as an epoxy resin having an epoxy equivalent of 180 to 2500, an epoxy resin obtained by a reaction between a polyphenol compound and an epihalohydrin, for example, epichlorohydrin, is particularly preferable from the viewpoint of the corrosion resistance of the coating film. Of these, bisphenol A diglycidyl ether obtained by reaction of bisphenol A and epichlorohydrin is most suitable. In addition, an epoxy resin obtained by polymerizing bisphenol A as a basic structure exhibits the same effect, and an epoxy equivalent having an epoxy equivalent of 180 to 2500, preferably 180 to 2000, more preferably 180 to 1500 is optimal. In the modified epoxy resin, these epoxy resins are contained in an amount of 5 to 30% by weight.

Next, bisphenol A is used to control the skeleton molecular weight of the epoxy resin. The epoxy equivalent can be controlled by this content (addition amount). In the modified epoxy resin, 5 to 30% by weight of bisphenol A is contained.

Next, the primary and / or secondary amino group-containing compound is a cationic component for introducing an amino group into the epoxy resin substrate to cationize the epoxy resin. The amine used here contains at least one active hydrogen that reacts with an epoxy group. Examples of the amino group-containing compound used for such purpose include mono- or di-alkylamines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine and the like. Alkanolamines such as monoethanolamine, diethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylaminoethanol; ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, Alkylene such as tetraethylenepentamine, pentaethylenehexamine, diethylaminopropylamine, diethylenetriamine, triethylenetetramine Riamin and ketimine of these polyamines; ethyleneimine, alkylene imine such as propylene imine; piperazine, a cyclic amine such as morpholine, and the like. In the modified epoxy resin, the primary and / or secondary amino group-containing compound is contained in an amount of 0.5 to 20% by weight.

* Method for producing aminated product of modified epoxy resin of bisphenol A type First, a predetermined amount of a modified resin and an epoxy resin are mixed and heated and stirred. The heating temperature is preferably 70 to 100 ° C. After each raw material is dissolved, a catalyst is added, the heating temperature is increased, and synthesis is performed. As the catalyst, a tertiary amine such as dimethylbenzylamine is usually used. The synthesis temperature is generally controlled at 120 ° C to 170 ° C.

By adjusting the synthesis temperature and time, a modified epoxy resin having a predetermined epoxy equivalent can be synthesized. The epoxy equivalent is calculated by the epoxy equivalent measurement defined in JIS K7236. The epoxy equivalent at this time is preferably 800 to 10,000, more preferably 800 to 5000, and most preferably 800 to 3000. As the epoxy equivalent increases, emulsification at the time of preparing the emulsion becomes more difficult.

Next, a primary and / or secondary amino group-containing compound is added to the synthesized modified epoxy resin. An aminated product of the modified epoxy resin can be obtained by adding a primary and / or secondary amino group-containing compound while maintaining the modified epoxy resin at 60 ° C. to 110 ° C. and performing synthesis for 1 to 3 hours.

* Cationization of the modified epoxy resin A neutralized acid is added to the aminated product of the modified epoxy resin, mixed with stirring, and diluted with water to prepare a resin emulsion having a predetermined concentration. As the neutralizing acid, formic acid, acetic acid, lactic acid, sulfamic acid and the like are used.

In this case, it is preferable to add a curing agent, a curing catalyst, an organic solvent, etc. before adding the neutralizing acid. By adding in advance in this way, a uniform emulsion can be obtained.

* Content of the cationic resin in the dispersoid The content of the cationic resin (especially the aminated product of the modified epoxy resin) in the dispersoid of the emulsion is based on the total weight of the dispersoid (total weight including the organic solvent). Is preferably 30 to 80% by weight.

(Composition component: Dispersoid of cationic resin emulsion / curing agent)
* Component The hardening | curing agent contained in the dispersoid of the cationic resin emulsion which concerns on this invention is block polyisocyanate. Block polyisocyanate is an addition reaction product of approximately the theoretical amount of a polyisocyanate compound and an isocyanate blocking agent. Examples of the polyisocyanate compound used here include tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate (usually referred to as “MDI”), Aromatic, aliphatic or alicyclic polyisocyanate compounds such as crude MDI, bis (isocyanate methyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate; cyclized polymers of these polyisocyanate compounds; Isocyanate biuret; ethylene glycol, propylene glycol, trimethylolpropane in excess of these isocyanate compounds Hexanetriol, and the like terminal isocyanate-containing compounds obtained by reacting a low molecular weight active hydrogen-containing compounds such as castor oil. These can be used alone or in combination of two or more.

On the other hand, the isocyanate blocking agent is blocked by adding to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound produced by the addition is stable at room temperature, but the baking temperature of the coating film (usually about 100). When heated to about 200 ° C., it is desirable that the blocking agent dissociates to regenerate free isocyanate groups.

Examples of the blocking agent satisfying such requirements include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenols such as phenol, para-t-butylphenol and cresol Compounds; aliphatic alcohols such as n-butanol and 2-ethylhexanol; aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; ether alcohol compounds such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether Can be mentioned. These blocking agents can be used alone or in combination of two or more. In addition, in order to efficiently advance the dissociation and curing reaction of the blocking agent, and to generate the intended curing reaction product, a part of the isocyanate group is added to the modified epoxy resin skeleton in advance, and the remaining isocyanate A method of blocking a group with a blocking agent is used.

* Content of blocked polyisocyanate in the dispersoid The block polyisocyanate in the dispersoid of the emulsion is preferably 5 to 40% by weight based on the total weight of the dispersoid (total weight including the organic solvent). is there.

(Composition component: Dispersoid of cationic resin emulsion / tin compound)
* Component The tin compound contained in the dispersoid of the cationic resin emulsion according to the present invention contains a tin compound represented by Formula 1. In the present invention, the use of the tin compound alone represented by formula 1 is not limited, but a tin compound such as a dibutyltin compound having a m of 3 or less, a solid tin compound, other curing catalysts, Can be used in combination.

As described above, the dispersoid of the resin emulsion is composed of a cationic resin, a curing agent, a curing catalyst, an organic solvent, and the like. For improving the precipitation of Bi, hydrophobic / hydrophilicity in components other than the cationic resin is used. Therefore, a compound having m of 4 or more shown in Formula 1 is preferable. Furthermore, a tin compound having a high hydrophobicity m of 7 or more is preferable, and among them, a dioctyl tin compound having a high catalytic ability of m 7 is most preferable. The upper limit is 12, for example.

In addition, compounds having n of 11 or more are not suitable because they have poor compatibility with the resin, resulting in poor stability of the emulsion, insufficient curability, and generation of repellency and blisters.

Here, from the viewpoints of improving the precipitation of Bi and preventing the occurrence of repellency and bumps, a particularly preferred combination of m and n is 4 ≦ m ≦ 10 (more preferably 6 ≦ m ≦ 8) and 0 ≦ n ≦ 5 (more preferably, 0 ≦ n ≦ 3). A more preferable combination is a total number of m and n of 7 to 10, and a most preferable combination is a total of m and n of 7 (for example, dialkyltin diacetate). For example, as shown in Examples and Comparative Examples, dioctyltin diacetate (m = 7, n) having high hydrophobicity compared to the case of using dibutyltin diacetate (m = 3, n = 0) having low hydrophobicity. = 0), the Bi precipitation is dramatically improved.

* Mechanism of action By the way, as described above, when a tin compound having a specific structure as described above is used in a specific system, the precipitation mechanism of Bi is dramatically improved and the occurrence of repellency and bumps can be prevented. Is considered as follows.

In consideration of the composition of the dispersoid component in the cationic resin emulsion, the aminated product of the modified epoxy resin can obtain an affinity with water as a medium due to the cationization ability of the amine moiety that it has (emulsification). ). On the other hand, the blocked polyisocyanate that is a curing agent and the tin compound that is a curing catalyst have low affinity with water due to chemical structural characteristics, and are difficult to exist on the surface of the dispersoid, and are likely to exist inside the dispersoid. . That is, it can be easily expected to have a core-shell structure in which an aminated product of a modified epoxy resin is used as a shell and a blocked polyisocyanate or tin compound is used as a core.

In this case, the surface state of the dispersoid changes depending on the hydrophobicity / hydrophilicity of the core component. The higher the hydrophobicity of the core component, the more difficult it is to exist near the surface of the dispersoid, and the more the core component is, the lower the hydrophobicity, the closer to the surface of the dispersoid.

Under normal conditions (electroless), even if a stable emulsion state is realized by sufficient cationization in the aminated product of the modified epoxy resin, it has a low affinity with water, but a component with low hydrophobicity. Is present in the vicinity of the surface of the dispersoid, the instability of the emulsion increases due to subtle changes in cationization at the substrate interface during the first step.

Specifically, even in a low-voltage electrolysis state (first step), the emulsion is concentrated, the degree of instability increases, and in some cases, precipitation of a resin component that is a dispersoid may occur.

In the present invention, if the resin component is deposited in the low-voltage electrolysis state, Bi deposition is hindered, which is inconvenient. In other words, compared with a tin compound having low hydrophobicity, Bi precipitation is made difficult to be inhibited by using a tin compound having high hydrophobicity that can exist in the core portion. That is, Bi precipitation property improves.

The hydrophobicity of the tin compound greatly contributes to its structure, particularly the numerical value of m in Formula 1. The larger the value of m, the higher the hydrophobicity and the more it exists in the core portion, that is, it is difficult to inhibit the Bi precipitation, and the Bi precipitation is improved.

The dialkyl tin difatty acid ester represented by Formula 1 is liquid at room temperature and has excellent compatibility with the resin. In addition, there is no occurrence of repellency or flutter due to these.

When the resin is deposited by electrolysis and the dispersoid of the emulsion is united, the tin compound present on the outermost surface comes into contact with moisture, and in that case, the dialkyltin difatty acid ester in contact with moisture Is preferably hydrolyzed to easily form a dialkyltin oxide. That is, in addition to the easy removal of the fatty acid moiety, it is preferably a fatty acid root that is easy to move to the aqueous phase after removal (high hydrophilicity). Thereby, the excess component contained in a coating film reduces by moving to the water phase side, and implement | achieves sclerosis | hardenability improvement and corrosion resistance improvement. From this viewpoint, it is preferable that n is equal to or less than the above-described numerical value. On the other hand, the higher fatty acid ester portion and the like are not easily hydrolyzed and are likely to remain in the coating film, which may cause a decrease in curability and a decrease in corrosion resistance. For example, in evaluating curability, after pressing a gauze that has been enriched with acetone and reciprocating, and visually checking the appearance of the coating film, if there are components that do not contribute to curing, Since the component is dissolved in acetone, the appearance of the coating film is confirmed on the appearance of the coating film.

* Content of tin compound in the dispersoid of the emulsion If the content of tin compound is too high, it is economically disadvantageous. In addition, the core part of the core-shell structure becomes a huge structure, and the balance with the shell part having the ability to emulsify cannot be achieved. The lack of a shell portion that wraps around the enormous core portion to form an emulsion makes it easier for the emulsion to agglomerate and coalesce, making it impossible to take the state of a resin emulsion.

Therefore, the ratio with the resin component that becomes the shell portion is also important. The amount of tin compound in the dispersoid of the emulsion is preferably 0.05 to 3% by weight as Sn based on the total weight of the dispersoid (total weight including the organic solvent). 2% by weight is more preferable, and 0.05 to 1% by weight is most preferable.

In addition, the amount of tin compounds in the aqueous composition for metal surface treatment or the dispersoid can be grasped as the amount of Sn. When heated at a high temperature of about 600 ° C. for a long time, the components such as the resin are burned, and all the tin compounds are in a tin oxide state. The tin oxide obtained here is dissolved with hot concentrated sulfuric acid or the like to prepare an aqueous solution, and this is subjected to ICP emission analysis or ICP mass spectrometry, whereby the Sn amount can be measured.

<Composition component: Dispersion medium of cationic resin emulsion>
(Composition component: dispersion medium / liquid medium of cationic resin emulsion)
As the liquid medium of the aqueous composition for metal surface treatment according to the present invention (the liquid medium as the dispersion medium of the cationic resin emulsion), an aqueous medium is preferable, and water is more preferable. When the liquid medium is water, the liquid medium may contain an aqueous solvent other than water (for example, water-soluble alcohols) (for example, 10% by weight based on the weight of the total liquid medium). Less than).

(Composition component: dispersion medium of cationic resin emulsion / trivalent bismuth ion)
Bi ion as used in the field of this invention refers to the Bi component which does not solidify in a composition, specifically comprises a chelate by aminopolycarboxylic acid etc. which will be described later, and is in a completely dissolved state. The ions are present in the dispersion medium of the emulsion.

The Bi ion supply source is not particularly limited as long as it is a trivalent bismuth compound. For example, inorganic bismuth compounds such as bismuth nitrate, bismuth phosphate, bismuth sulfate, bismuth oxide, and bismuth hydroxide, fluoride Examples thereof include halogenated bismuth compounds such as bismuth, bismuth chloride, bismuth bromide, and bismuth iodide, and organic acid bismuth compounds such as bismuth acetate, bismuth formate, bismuth lactate, and bismuth citrate.

In the present invention, aminopolycarboxylic acid may be contained. Aminopolycarboxylic acid is a general term for chelating agents having an amino group and a plurality of carboxyl groups in the molecule. The aminopolycarboxylic acid can contain the aminopolycarboxylic acid in order to make the trivalent Bi ions in the composition more water-soluble. Specific examples include EDTA (ethylenediaminetetraacetic acid), HEDTA (hydroxyethylethylenediaminetriacetic acid), NTA (nitrilotriacetic acid), DTPA (diethylenetriaminepentaacetic acid), TTHA (triethylenetetraminehexaacetic acid), and the like. From the viewpoint of chelate stability with ions, EDTA, HEDTA, and NTA are more preferable.

<Composition component: Other ingredients>
In the composition of the present invention, additives usually used in the paint field such as a pigment, an organic solvent, a pigment dispersant, and a surfactant can be further applied as necessary. Examples of the pigment include colored pigments such as titanium white and carbon black, extender pigments such as clay, talc, and barita, and rust preventive pigments such as aluminum tripolyphosphate and zinc phosphate. In the above description, the components in the dispersoid of the cationic resin emulsion (cationic resin, blocked polyisocyanate, tin compound) and the components in the dispersion medium (liquid medium, bismuth ions) have been described. It means that it exists in the dispersoid or dispersion medium, and does not mean that it exists only in the dispersoid or only in the dispersion medium. For example, even if a part of the cationic resin is dissolved in a small amount in the dispersion medium, it is within the scope of the present invention.

<Composition of composition>
Next, the composition of the aqueous composition for metal surface treatment according to the present invention will be described. First, the metal surface treatment aqueous composition according to the present invention can be adjusted to a desired concentration by appropriately diluting a high concentration product with water. Hereinafter, the suitable concentration of each component in the aqueous composition will be described.

(Cationic resin in aqueous composition)
The composition preferably contains 5-30% by weight (solid content) of the cationic resin, more preferably 5-20% by weight, and more preferably 5-15% by weight based on the total weight of the composition. % Is included.

(Blocked isocyanate in aqueous composition)
The composition contains 2 to 20 wt% (solid content) of blocked isocyanate, more preferably 2 to 15 wt%, more preferably 2 to 10 wt% based on the total weight of the composition.

(Tin compound in aqueous composition)
The content of the tin compound in the composition is preferably 0.01 to 1% by weight, more preferably 0.01 to 0.5% by weight as the Sn amount, Most preferred is ˜0.2% by weight. If the content of the tin compound is too low, the expected curing catalyst ability will be reduced and the curability will not be satisfied, and if the acetone reciprocation test is performed as described above, it will be confirmed that the coating has been peeled off. It becomes.

(Trivalent Bi ion in aqueous composition)
The composition contains 100 to 5000 ppm of trivalent Bi ions. More preferred is 500 to 4000 ppm, and most preferred is 1000 to 3000 ppm. If the Bi ion concentration is too low, it is disadvantageous for the precipitation of Bi. If the Bi ion concentration is too high, the electrical conductivity of the composition becomes too high, and the coverage of the film on a metal material having a complicated shape deteriorates, and Bi adheres. Excessive amount may impair film adhesion. The Bi ion concentration in the composition can be determined by solid-liquid separation of the composition using an ultracentrifuge, and the liquid phase can be quantified using high frequency inductively coupled plasma emission spectrometry (ICP) or atomic absorption spectrometry (AA). .

<Physical properties of aqueous composition for metal surface treatment>
(PH)
The pH of the aqueous composition for metal surface treatment according to the present invention is not particularly limited, but is usually adjusted to 2.0 to 7.0, preferably 3.0 to 6.5. Can do.

(temperature)
The temperature of the aqueous composition for metal surface treatment according to the present invention is not particularly limited, but when the film is deposited by electrolytic treatment, it is usually used within the range of 15 to 40 ° C, preferably 20 to 35 ° C. Can do.

≪Metal surface treatment film≫
The metal surface treatment film according to the present invention is obtained by the treatment method of the present invention using the aqueous composition for metal surface treatment of the present invention. Here, Bi which exists in a film | membrane exists with the form of a metal and an oxide. Bi deposited by cathodic electrolysis is basically reduced Bi metal Bi, but a part of it is oxidized in particular in the coating baking process to become an oxide. In addition, when a high voltage is applied in the second step, Bi stabilization by the aminopolycarboxylic acid is insufficient due to an increase in pH on the surface of the film, so that it also precipitates as oxidized Bi especially on the film surface side.

Bi coating weight is preferably 20 ~ 500mg / ^{m 2,} more preferably 30 ~ 400mg / ^{m 2,} and most preferably 50 ~ 300mg / ^{m 2.} If the amount of Bi deposited is too low, sufficient corrosion resistance cannot be obtained. If it is too high, improvement in corrosion resistance can no longer be expected, and film adhesion may be impaired. The amount of Bi attached can be quantified by fluorescent X-ray analysis. The “metal Bi adhesion amount” and “oxidized Bi adhesion amount” in the claims and in the present specification are values determined by the fluorescent X-ray analysis. In addition, the presence of hydroxides cannot be denied as other forms, but when quantified as “metal Bi” or “oxidized Bi” by the measurement method, the numerical value is “metal Bi adhesion amount” or “oxidized Bi”. It shall be referred to as “attachment amount”.

The total film thickness of the obtained film is preferably 5 to 40 μm, more preferably 5 to 30 μm, and most preferably 7 to 25 μm. If it is too thin, sufficient corrosion resistance cannot be obtained, and if it is too thick, not only is it economically disadvantageous, but the throwing power may be lowered. The film thickness can be measured by an electromagnetic induction type film thickness meter if the base metal is a magnetic metal, or by an eddy current film thickness meter if the base metal is a non-magnetic metal.

More Bi in the coating must be present on the base metal side than the coating surface. Specifically, the Bi adhesion amount B on the metal material side from the center of the film thickness is a Bi adhesion distribution in which the total Bi adhesion amount: 55% or more (B / A ≧ 55%) with respect to A. preferable. It is more preferably 58% or more, and most preferably 60% or more. If it is too low, sufficient corrosion resistance cannot be obtained. Note that if it exceeds 90%, the Bi concentration on the surface side of the film is extremely lowered and the function of Bi as a curing catalyst is lost.

The Bi adhesion distribution in the film can be measured by performing a line analysis on the film cross section using EPMA. The position of the base metal / film interface and the film surface is specified from the backscattered electron image taken at the same time, and the integrated value of Bi intensity in the film by EPMA line analysis: the integrated value of only the base metal side from the center of A and film thickness: B can be obtained and B / A can be calculated.

Preparation of blocked isocyanate Cosmonate M200 (manufactured by Mitsui Chemicals): methyl isobutyl ketone: 115.6 g was added to 678.4 g, the temperature was raised to 70 ° C., and then diethylene glycol monoethyl ether: 706.0 g was slowly added dropwise. After completion of the dropping, the temperature was raised to 90 ° C. The reaction was carried out at 90 ° C. for 12 hours to obtain a blocked isocyanate. When infrared absorption spectrum measurement was performed, absorption derived from unreacted isocyanate groups was not observed, and it was confirmed that the isocyanate was completely blocked.

Preparation of 30% Quaternary Salt Type Epoxy Resin A 1000 ml separable flask equipped with a thermometer, a condenser, and a stirrer was mixed with epoxy resin / jER # 828 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 180): 134.9 g, bisphenol A : 80.94 g and 0.1 g of dimethylbenzylamine were added, and the reaction was performed at 130 ° C. until an epoxy equivalent of 1200 was reached. After completion of the reaction, 71.7 g of butyl cellosolve was added, 13.16 g of dimethylaminoethanol and 14.79 g of 90% lactic acid were added, and the reaction was carried out at 90 ° C. for 1 hour. After the reaction, 613.36 g of deionized water was added dropwise over about 1 hour with vigorous stirring to produce a quaternary salt type epoxy resin having a solid content of 30%.

Production of cationic resin emulsion Production Example 1
A 1000 ml separable flask equipped with a thermometer, a condenser, and a stirrer was mixed with epoxy resin / jER # 828 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 180): 114.0 g, polycaprolactone diol / Placcel 208 (Daicel Chemical Co., Ltd.) as a modified resin. 41.5 g, bisphenol A: 45.6 g, and 0.1 g of dimethylbenzylamine were added, and the reaction was performed at 130 ° C. until the epoxy equivalent was 1000. After completion of the reaction, 55.5 g of butyl cellosolve was added, and 12.6 g of diethanolamine and 8.0 g of diethylenetriamine ketimine were added, and the reaction was carried out at 90 ° C. for 2 hours. Blocked isocyanate: 105.5 g, dioctyltin diacetate (Neostan U820 manufactured by Nitto Kasei Kogyo Co., Ltd.): 3.2 g and acetic acid 5.4 g were added and stirred until uniform, and then deionized water 578. 0.1 g was added dropwise over about 1 hour with vigorous stirring to obtain a cationic resin emulsion (A1) having a solid concentration of 33%.

Production Example 2
In Production Example 1, 1.6 g of dioctyltin diacetate and 1.6 g of dibutyltin diacetate (Neostan U200 manufactured by Nitto Kasei Kogyo Co., Ltd.) are used instead of dioctyltin diacetate, and a similar reaction is performed. A cationic resin emulsion (A2) was obtained.

Production Example 3
In Production Example 1, instead of dioctyltin diacetate, 3.2 g of dioctyltin dilaurate (Neostan U810 manufactured by Nitto Kasei Kogyo Co., Ltd.) is used, and a similar reaction is performed to obtain a cationic resin emulsion (A3). It was.

Production Example 4
In Production Example 1, instead of dioctyltin diacetate, 3.2 g of dibutyltin diacetate (Neostan U200 manufactured by Nitto Kasei Kogyo Co., Ltd.) was used, and the same reaction was carried out to obtain a cationic resin emulsion (A4). Obtained.

Production Example 5
In Production Example 1, 3.2 g of dioctyltin distearate (Neostan U500 manufactured by Nitto Kasei Kogyo Co., Ltd.) is used instead of dioctyltin diacetate, and a cationic resin emulsion (A5) is obtained by performing the same reaction. It was.

Preparation of pigment dispersion paste Production Example 6
To 16.6 parts of 30% quaternary salt type epoxy resin, 7.0 parts of purified clay, 0.3 part of carbon black, 3.0 parts of tertiary zinc phosphate and deionized water were added. Dispersion was carried out for 20 hours to obtain a pigment dispersion paste having a solid content of 50% by weight.

Preparation of Bi ionic liquid HEDTA: 13.3 g was dissolved in distilled water: 500 g and heated to 60 ° C., then bismuth nitrate pentahydrate: 23.2 g was added and stirred until the solid content was completely dissolved. . Distilled water was further added so that the total amount finally became 1.0 L, and Bi ion aqueous solution was produced.

Examples 1-3 and Comparative Examples 1-2
Preparation of Composition A pigment dispersion paste and an aqueous Bi ion solution having an inorganic solid content of 4.0% by weight were blended in a resin emulsion having an amount of solid content of 16.0% by weight in the combinations shown in Table 1. Example 1 To 3 and Comparative Examples 1 to 2 (Bi concentration in the composition: 1000 ppm; pH: 6.0; Cationic resin in the dispersoid: 58 wt%; Block isocyanate in the dispersoid: 27% by weight). Each concentration was adjusted by diluting with deionized water.

Electrolytic conditions After electrolysis at 8V for 90 seconds as an electrolytic step (1), an electrolytic treatment was immediately performed at 180V for 180 seconds as an electrolytic step (2).

Preparation of test plate A cold rolled steel plate: SPCC (JIS 3141) 70 × 150 × 0.8 mm (hereinafter abbreviated as SPC) was used as a test plate, and its surface was preliminarily a strong alkaline degreasing agent “FC-E2001” manufactured by Nihon Parkerizing Co., Ltd. Was degreased by spraying for 120 seconds. After the degreasing treatment, it was washed with spray water for 30 seconds, immersed in the compositions shown in Examples and Comparative Examples, and subjected to cathode electrolytic treatment under the electrolytic conditions shown in Examples and Comparative Examples. The test plate after completion of electrolysis was immediately rinsed with deionized water for 30 seconds and baked at 180 ° C. for 20 minutes in an electric oven.

Investigation of film characteristics The film characteristics of the film deposited on the test plate were investigated by the following method.
Film thickness measurement: Measured using an electromagnetic induction film thickness meter.
Bi adhesion amount: quantified by fluorescent X-ray spectroscopic analysis.
Bi adhesion distribution: Sample cross section was analyzed by EPMA line analysis. See below for specific methods.

The distribution distribution of Bi in the film was analyzed using EPMA. The metal material after the film treatment was fixed with an embedded resin, the cross section was polished, and a line analysis profile of Bi was obtained from the base metal direction to the deposited film surface direction. A line analysis profile is an average value of characteristic X-ray intensity calculated in an arbitrary width in the one-dimensional direction of an analysis area based on mapping analysis data, and can be interpreted as a line analysis having a width. The measurement conditions are as follows.

Measuring instrument: EPMA-1610 type manufactured by Shimadzu Corporation Electron gun: CeB6 cathode type Beam current: 50 nA, beam voltage: 15 kV, beam diameter: 1 μmφ or less Integration count: once, sampling time per point: 100 ms
Spectroscopic crystal: PET (Bi Mα)

The position of the interface between the base metal and the film and the surface of the film is identified from the backscattered electron image taken at the same time, and the integrated value of Bi intensity in the film: A and the integrated value only on the base metal side from the center of the film thickness: B are obtained, B / A was calculated. For reference, FIG. 2 shows the analysis result of the film obtained in Example 1 as a representative profile.

Bi precipitation property: As Bi precipitation property, the time required for the Bi precipitation amount to reach 50 mg / m ² was evaluated from the result of fluorescent X-ray spectroscopic analysis over time. Evaluation criteria were within 45 seconds: A, 45-60 seconds: B, 60 seconds or more: X. The results are shown in Table 1, and the transition of the precipitation amount is shown in FIG. In the Bi precipitation test, electrolysis was performed at 8 V for 30, 60, and 90 seconds, washed with deionized water, and then air-dried.

Coating film curability: Gauze with plenty of acetone was pressed against a resin-coated plate produced by cathodic electrolysis, and after 30 reciprocations, the appearance of the coating film was visually confirmed. The evaluation criteria were as follows: no mark: ◎, mark: ◯, visible state: x. The results are shown in Table 1.

Resin deposition time (resin deposition property): Electrolytic treatment was performed at 15 V for 90 seconds, and the time when a decrease in current value was observed was determined as the time when coating film resistance was expressed, that is, the time when resin deposition occurred. The processing time up to was defined as resin deposition time. The results are shown in Table 1.

Hashiki, Futsu: The presence or absence was confirmed visually.

Adhesiveness: 100 square grid cuts with a width of 1 mm were put on the coating film, and the portion was extruded with an Eriksen tester. After extrusion, tape peeling was performed, and the number of cells remaining without peeling was counted. Extrusion distance: 4 mm Remaining mass number 80-100: A, 80-60: A, 60-20: A, 20-0: X

As is clear from Table 1, the compositions according to the examples can improve the precipitation of Bi, prevent deterioration of the appearance of the coating film such as repellency and blistering, and have excellent coating film curability and adhesion. It was confirmed that That is, it was confirmed that the compositions according to the examples can form a film in the same bath and can form a film satisfying important properties as a film. On the other hand, it can be seen that the composition according to the comparative example is remarkably inferior in any property and cannot be used as a practical product.

Claims (10)

1. An aqueous composition for metal surface treatment containing a cationic resin emulsion, wherein the dispersoid of the cationic resin emulsion comprises an aminated product of a modified epoxy resin, a block polyisocyanate, and a formula 1:
   

   

   (Wherein, in Formula 1, m is 4 or more, n is 0 or more and 10 or less), and the dispersion medium of the cationic resin emulsion contains Bi ions. An aqueous composition for surface treatment.
2. M in Formula 1 is 7 or more, The aqueous composition for metal surface treatment of Claim 1 characterized by the above-mentioned.
3. M in Formula 1 is 7, The aqueous composition for metal surface treatment of Claim 1 or 2 characterized by the above-mentioned.
4. The aqueous composition for metal surface treatment according to claim 3, wherein m in Formula 1 is 7 and n is 0.
5. The aqueous composition for metal surface treatment according to any one of claims 1 to 4, wherein the content of the tin compound in the whole composition is 0.01 to 1% by weight as Sn amount.
6. The aqueous composition for metal surface treatment according to any one of claims 1 to 5, which is a composition used for a multistage energization method in the same bath.
7. A metal material to be treated is immersed in the aqueous composition according to any one of claims 1 to 6, and a film is deposited on the metal material in an electrolytic treatment process using the metal material to be treated as a cathode. Metal surface treatment method.
8. In the electrolytic treatment step, the metal material having a cleaned surface is immersed in the aqueous composition according to any one of claims 1 to 6 or while the metal material is used as a cathode. A first step of electrolysis at a voltage of 15 V or less for 10 to 120 seconds, and a second step of electrolysis for 30 to 300 seconds at a voltage of 50 to 400 V, which is carried out in the same bath following the first step. The metal surface treatment method according to claim 7, wherein:
9. A method for producing a coated metal material, comprising the electrolytic treatment step according to claim 7 or 8.
10. 10. A film obtained by the production method according to claim 9, wherein the metal Bi and the oxidized Bi adhere as 20 to 250 mg / m ² as Bi, the total film thickness is 5 to 40 μm, and the metal material from the center of the film thickness A metal surface treatment film characterized in that the Bi adhesion amount on the side: B is a Bi adhesion distribution that is 55% or more (B / A ≧ 55%) with respect to the total Bi adhesion amount: A.

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