JP2008088551A - Method of treating surface of metal base performed as pretreatment for cation electrodeposition coating, metal surface treatment composition used therefor, metallic material having excellent sticking property in electrodeposition coating, and method of coating metal base - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic surface treatment composition, in cation electrodeposition coating, capable of improving a sticking property of a metal base without depending on the kind of a metal base, to provide a method of treating the surface of a metallic base using the metallic surface treatment composition, to provide a metallic material treated by the method for treating a metallic surface, and to provide a method of coating a metal base. <P>SOLUTION: The metallic surface treatment composition for forming a rust preventive film having the sticking property in electrodeposition coating before cation electrodeposition coating, on a metal base having a plurality of curved parts, contains zirconium ions and/or titanium ions, and a stabilizer for suppressing the elution of the components in the rust preventive film upon the cation electrodeposition coating. The method of treating a metallic surface uses the composition. The metallic material which is treated therewith, and the method of coating a metal base are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the cationic electrodeposition coating applied to a metal substrate having a plurality of curved portions, the present invention is a metal surface treatment method performed as a pretreatment for cationic electrodeposition coating in order to form a rust-preventive film having excellent throwing power, The present invention relates to a metal surface treatment composition used in the metal surface treatment method, a metal material excellent in throwing power of a cationic electrodeposition paint, and a method for coating a metal substrate.

  Cationic electrodeposition coating is applied to metal substrates (coating objects) that have multiple curved parts such as curved surfaces and bag parts obtained by bending metal plates, and joints between metal plates. Can be applied. In addition, since it can be applied automatically and continuously, it has been widely put into practical use as an undercoating method for metal substrates having a large number of curved surfaces and bag portions, particularly for automobile bodies. Cationic electrodeposition coating is performed by immersing an object to be coated in a cationic electrodeposition coating composition as a cathode and applying a voltage.

  The deposition of the coating film in the process of cationic electrodeposition coating is due to an electrochemical reaction, and when a voltage is applied, the components in the electrodeposition coating material migrate to the surface of the object to be coated by electrophoresis. A coating film is deposited on the surface. Since the deposited coating has insulating properties, the electrical resistance of the coating increases as the deposition of the coating proceeds and the thickness of the coating increases in the electrodeposition coating process.

  As a result, the deposition of the coating film on the part decreases, and instead, the deposition of the coating film on the undeposited part starts. In this way, the coating film is deposited sequentially on the undeposited portion, and the electrodeposition coating of the entire article to be coated is completed. In this specification, the property that a continuous electrodeposition coating film is formed by sequentially depositing an insulating coating film on an undeposited portion of a metal base material that is an object to be coated is called throwing power.

  In cationic electrodeposition coating, as described above, an insulating coating film is sequentially formed on the surface of the object to be coated, so theoretically it has infinite throwing power, and all of the object to be coated is present. A coating film can be uniformly formed on the portion.

  However, even when the coating film is deposited on the surface of the object to be coated, if the electrical resistance of the coating film does not increase for some reason, the throwing power of the electrodeposition coating material is remarkably lowered. For this reason, unevenness occurs in the film thickness, which greatly affects the corrosion resistance.

  When cationic electrodeposition coating is applied to a metal substrate, surface treatment is usually performed for the purpose of improving various properties such as corrosion resistance and coating film adhesion. From the standpoint that coating film adhesion and corrosion resistance can be further improved, phosphoric acid chromate surface treatment compositions that have been used in surface treatments in recent years have been affected by the harmful effects of chromium on the environment. There are concerns. For this reason, zinc phosphate-based surface treatment compositions have been used as surface treatment agents that do not contain chromium (see, for example, Patent Document 1).

  However, zinc phosphate-based surface treatment compositions are not preferable from the viewpoints of economy and workability, such as high costs for wastewater treatment because of their high metal ion concentration and acid concentration and very high reactivity. Furthermore, in the chemical conversion treatment with a zinc phosphate-based surface treatment agent, water-insoluble salts are generated along with the metal surface treatment, and are deposited as precipitates in the chemical treatment tank. Such precipitates are generally called sludge, and the cost associated with the removal and disposal of sludge is regarded as a problem. In addition, phosphate ions may cause environmental load such as eutrophication of rivers and oceans. In addition, in the surface treatment with a zinc phosphate-based surface treatment composition, it is necessary to adjust the surface, and there is a problem in production efficiency that the surface treatment process is complicated and long. .

  Metal surface treatment agents composed of zirconium compounds and / or titanium compounds have been known as surface treatment compositions to replace such phosphate chromate or zinc phosphate surface treatment compositions.

  For example, Patent Document 2 discloses a water-based surface treatment liquid for surface-treating metal materials selected from iron-based materials, zinc-based materials, aluminum-based materials, and magnesium-based materials individually or in combination of two or more thereof. And containing at least one compound selected from a zirconium compound and a titanium compound as the metal element in an amount of 5 ppm to 5000 ppm, a free fluorine ion of 0.1 ppm to 100 ppm, and a pH of 2 to 6. A metal surface treatment solution is disclosed. According to this treatment liquid for surface treatment, a ferrous material, a zinc-based material, an aluminum-based material, and a magnesium-based material that do not contain sludge in a treatment bath that does not contain environmentally harmful components, which is impossible with the prior art. It is said that a surface treatment film having excellent corrosion resistance after coating can be deposited on a metal surface composed of two or four kinds of system materials simultaneously or individually.

  Patent Document 3 discloses a pre-coating method for treating a workpiece with a chemical conversion treatment agent to form a chemical conversion film, and the chemical conversion treatment agent is selected from the group consisting of zirconium, titanium, and hafnium. There is disclosed a coating pretreatment method characterized by comprising at least one selected from the group consisting of at least one fluorine and an amino group-containing silane coupling agent, a hydrolyzate thereof, and a polymer thereof. According to this coating pretreatment method, since no zinc phosphate-based treatment agent is used, the load on the environment is small, and the conventional pretreatment with a chemical conversion treatment agent made of zirconium is not suitable. However, a chemical conversion film having excellent coating film adhesion can be formed.

  Patent Document 4 discloses a chemical conversion treatment agent comprising at least one selected from the group consisting of zirconium, titanium, and hafnium, fluorine, an adhesion imparting agent, and a chemical conversion reaction accelerator, wherein the adhesion imparting agent is zinc , Manganese and cobalt ions selected from the group consisting of at least one metal ion (A), alkaline earth metal ion (B), Periodic Table Group 3 metal ion (C), copper ion (D), silicon-containing Compound (E), water-soluble resin (F) such as polyvinylamine and / or polyallylamine, water-soluble epoxy compound (G) having an amino group, and silane coupling agent and / or hydrolyzate thereof (H) At least one selected from the group, and the chemical reaction accelerator is nitrite ion, nitro group-containing compound, hydroxylamine sulfate, persulfate ON, sulfite ion, hyposulfite ion, peroxide, iron (III) ion, iron citrate compound, bromate ion, perchlorate ion, chlorate ion, chlorite ion, ascorbic acid, citric acid, tartaric acid And a chemical conversion treatment agent characterized in that it is at least one selected from the group consisting of malonic acid, succinic acid, and salts thereof, and the amount of the chemical reaction accelerator is 1 ppm to 5000 ppm. . According to this chemical conversion treatment agent, it is possible to obtain a chemical conversion film having good performance by suppressing unevenness of the chemical conversion film due to unevenness in the amount of the film deposited on the substrate. Furthermore, by improving the stability of the chemical conversion film, a chemical conversion film excellent in coating film adhesion is formed even on an iron-based substrate that has been unsuitable for pretreatment with a chemical conversion treatment agent made of zirconium or the like. be able to.

Further, Patent Document 5 discloses (A) a compound containing at least one element selected from the group consisting of Ti, Zr, Hf, and Si, (B) a compound containing Y and / or a lanthanoid element, and ( C) Nitric acid and / or nitric acid compound, and the ratio of the total mass concentration B of the Y and / or lanthanoid elements in the component (B) to the total mass concentration A of the elements in the component (A) A certain K1 = B / A is 0.05 ≦ K1 ≦ 50, and is a ratio of the total mass concentration C in terms of NO ₃ of nitrogen atoms in the component (C) to the total mass concentration A K2 = C / A treatment solution for surface treatment of a metal containing iron and / or zinc, wherein A is 0.01 ≦ K2 ≦ 200, and the total mass concentration A is 10 ppm ≦ A ≦ 10000 ppm, and further ethylenediaminetetraacetic acid, Glucon Contains 1 ppm to 1000 ppm of at least one selected from the group consisting of acids, heptogluconic acid, glycolic acid, citric acid, succinic acid, fumaric acid, aspartic acid, tartaric acid, malonic acid, malic acid, salicylic acid, and salts thereof A surface treatment liquid is disclosed. According to this surface treatment liquid, it is supposed that a surface treatment film having excellent corrosion resistance after coating can be deposited on the surface of a metal material in a treatment bath that does not contain components harmful to the environment.
Japanese Patent No. 30886623 JP 2004-190121 A Japanese Patent Application Laid-Open No. 2004-218070 JP 2004-218075 A JP 2006-161117 A

  However, in the zirconium-based surface treatment composition of Patent Document 2, depending on the type of the metal substrate, in the cationic electrodeposition coating after the surface treatment, a coating film cannot be formed uniformly, resulting in uneven film thickness. There was a problem that occurred. In addition, there is a problem that a uniform film is difficult to be formed on an SPC steel plate or a high-tensile steel plate having a high silicon content, and the corrosion resistance is inferior to that of zinc phosphate. In the case where the coating film cannot be formed uniformly, the electrodeposition coating effect cannot be obtained at a portion where the coating film is not sufficiently formed, causing a decrease in corrosion resistance. In addition, accumulation of iron ions eluted from the iron-based metal base material in the treatment bath causes problems such as generation of sludge and deterioration of corrosion resistance.

  On the other hand, it is possible to increase the coating amount over the entire surface of the metal substrate by increasing the voltage, but this is not preferable in terms of cost. In addition, there is a problem that pinholes and craters are generated, resulting in poor appearance. The reason for this is thought to be that spark discharge is likely to occur in hydrogen gas because zinc steel sheet has a lower discharge voltage of hydrogen gas generated on the substrate side during cationic electrodeposition coating than iron steel sheet. Yes.

  In addition, the pre-painting treatment method of Patent Document 3 is not limited to a painting method, has a low environmental impact, and can be applied to all metals such as iron, zinc, aluminum, etc. before coating. Although a treatment method is disclosed, there is no disclosure or suggestion about the problems related to the corrosion resistance and electrodeposition property of the chemical conversion film alone.

  Patent Document 4 discloses a chemical conversion treatment agent containing a hydroxy acid such as ascorbic acid, citric acid, tartaric acid and the like as a stabilizer that suppresses elution of components in the anticorrosive film during cationic electrodeposition coating in the present invention. It is disclosed. However, these hydroxy acids have been used to obtain a chemical conversion film having good performance by suppressing unevenness of the chemical conversion film due to the uneven amount of the film deposited on the substrate. Furthermore, by improving the stability of the chemical conversion film, it is possible to form a chemical conversion film excellent in coating film adhesion even on an iron-based substrate that has been conventionally unsuitable for pretreatment with a chemical conversion treatment agent composed of zirconium or the like. It was used for. Therefore, the chemical conversion treatment agent described in Patent Document 4 is not used for improving the throwing power at the time of cationic electrodeposition coating, and if added, the problem of throwing power is still apparent at the time of filing. It was not converted.

  Patent Document 5 discloses a treatment liquid for surface treatment containing a hydroxy acid, an amino acid, an aminocarboxylic acid, and / or an aromatic acid. As the hydroxy acid, gluconic acid, heptogluconic acid, glycolic acid, citric acid is disclosed. , Tartaric acid, malonic acid, and malic acid, aspartic acid as amino acid, ethylenediaminetetraacetic acid as aminocarboxylic acid, and salicylic acid as aromatic acid are disclosed. However, the above compound is added as a chelating agent for preventing the metal ions eluted in the surface treatment composition from becoming sludge, and the components in the chemical conversion film obtained by the surface treatment are eluted. It is not used to prevent itself.

  The present invention has been made in view of the above problems, and an object of the present invention is a metal surface treatment method using a metal surface treatment composition containing zirconium and / or titanium ions, and further corrosion resistance is obtained. A metal surface treatment method capable of forming a rust-proof coating that can improve the throwing power regardless of the type of metal substrate in cationic electrodeposition coating, and the metal surface used in this metal surface treatment method It is providing the processing method, the metal material processed by this metal surface treatment method, and the coating method of a metal base material.

  When the zirconium-based and titanium-based metal surface treatment composition is used as a metal substrate, the present inventors do not form a coating film uniformly in the subsequent cationic electrodeposition coating, that is, the throwing power decreases. I encountered the problem of doing. The said problem was remarkable when it used for ferrous metal base materials, such as a SPC steel plate. Based on this knowledge, the present inventors have conducted extensive research, and as a result, the cause of the reduction in throwing power is that the film resistance of the anticorrosive film is significantly greater than the film resistance of the conventionally known zinc phosphate-based film. I found out that it was mainly due to low. Furthermore, the present inventors have found that the cause of the reduction in throwing power is that the components in the rust preventive coating are eluted from the rust preventive coating during cationic electrodeposition coating, and the dissolved components enter the electrodeposited coating. It has been found that this is because it acts electrolytically and also reduces the coating resistance of the electrodeposition coating.

  Furthermore, a metal for pretreatment of cationic electrodeposition coating, comprising zirconium ions and / or titanium ions, an adhesion-imparting agent, and a stabilizer that suppresses elution of components in the rust-preventive coating during cationic electrodeposition coating. Discovered that when a metal substrate is treated with the surface treatment composition, the throwing power and corrosion resistance in the subsequent electrodeposition coating are improved, and the bath stability of the metal surface treatment composition is improved, and the present invention is completed. It came to do. Specifically, the present invention provides the following.

  (1) A metal surface treatment method for forming a rust-preventive film having excellent electrodeposition-preventing property before cationic electrodeposition coating on a metal substrate having a plurality of curved portions, the metal surface treatment The method comprises a cationic electrodeposition coating comprising zirconium ions and / or titanium ions, an adhesion-imparting agent, and a stabilizer that suppresses elution of components in the rust preventive film during the cationic electrodeposition coating. Using a metal surface treatment composition for pretreatment, a metal surface treatment method characterized by forming a rust preventive film excellent in throwing power on the metal substrate, the adhesion imparting agent, A metal surface treatment method that is at least one selected from the group consisting of (A) a silicon-containing compound, (B) an adhesion-imparting metal ion, and (C) an adhesion-imparting resin.

  (2) The stabilizer is at least one selected from the group consisting of hydroxy acids, amino acids, aminocarboxylic acids, aromatic acids, phosphonic acid compounds, sulfonic acid compounds, and polyvalent anions. The metal surface treatment method as described.

  (3) The metal surface treatment method according to (2), wherein the amino acid is at least one selected from the group consisting of alanine, glycine, glutamic acid, aspartic acid, histidine, phenylalanine, proline, tyrosine, and salts thereof. .

  (4) The aminocarboxylic acid is diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraaminehexaacetic acid (TTHA), 1,3-propanediaminetetraacetic acid (PDTA), 1,3 -Diamino-6-hydroxypropanetetraacetic acid (DPTA-OH), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA), dicarboxymethylglutamic acid (CMGA), and ( The metal surface treatment method according to (2), which is at least one selected from the group consisting of S, S) -ethylenediamine disuccinic acid (EDDS).

  (5) The polyvalent anion is at least one selected from the group consisting of phosphoric acid, condensed phosphoric acid, phosphonic acid, lignin, tannins, phenolic compounds, polyacrylic acid, and saccharides. Metal surface treatment method.

  (6) The (A) silicon-containing compound is at least one selected from the group consisting of silica, silicofluoride, water-soluble silicate compound, silicate ester, alkyl silicate, and silane coupling agent ( The metal surface treatment method according to any one of 1) to (4).

  (7) The silane coupling agent is at least one selected from the group consisting of an aminosilane having at least one amino group in one molecule and a hydrolysis polycondensation product of the aminosilane, in the metal surface treatment composition. The total content of the zirconium ions and / or titanium ions is 10 ppm or more and 10,000 ppm or less in terms of a metal element, and the total content of the aminosilane and / or the hydrolyzed polycondensate of the aminosilane in the metal surface treatment composition. Is 1 ppm or more and 2000 ppm or less in terms of silicon element, and the ratio of the total content of zirconium element and / or titanium element to the total content of silicon element contained in the aminosilane and / or hydrolysis polycondensate of aminosilane Is 0.5 or more and 500 or less Metal surface treatment method according to 6).

  Here, the “total content” refers to the total mass of the solid content of the compound, the element and the ion contained in the metal surface treatment composition, and any of the compounds is contained. Including the case where the amount is zero.

“Metal element conversion” refers to a metal element conversion coefficient (a coefficient for converting a metal compound amount into a metal element amount to the metal compound content. Specifically, the atomic weight of the metal element in the metal compound Is obtained by dividing the value by the molecular weight of the metal compound.) To obtain the target metal element amount. For example, the metal element equivalent concentration of zirconium of complex ion ZrF ₆ ²⁻ (molecular weight 205) 100 ppm is calculated to be 44 ppm by calculation of 100 × (91/205). Similarly, the silicon element equivalent concentration of 100 ppm of aminopropyltrimethoxysilane (molecular weight 179) is calculated as 16 ppm by the calculation of 100 × (28/179).

  (8) The (B) adhesion-imparting metal ion is at least one metal ion selected from the group consisting of magnesium, zinc, calcium, aluminum, gallium, indium, copper, iron, manganese, nickel, cobalt, and silver. The metal surface treatment method according to any one of (1) to (7).

  (9) The metal surface treatment according to any one of (1) to (8), wherein the (C) adhesion-imparting resin is at least one selected from the group consisting of a polyamine compound, a blocked isocyanate compound, and a melamine resin. Method.

［式（３）中、Ｒ^１は炭素数１から６のアルキレン基であり、Ｒ^２は下記化学式（４）から（６）で表される置換基であり、Ｒ^３はヒドロキシル基、炭素数１から６のアルコキシ基、又は炭素数１から６のアルキル基である。］

［式（６）中、Ｒ^６は水素原子、炭素数１から６のアミノアルキル基、又は炭素数１から６のアルキル基であり、Ｒ^７は、水素原子、又は炭素数１から６のアミノアルキル基である。］ (10) The polyamine compound is a polyamine compound having at least one selected from the group consisting of structural units represented by the following chemical formulas (1), (2), and (3): The ratio of the total content of zirconium element and / or titanium element to the mass of the compound is the metal surface treatment method according to (9), which is 0.1 to 100.

[In the formula (3), R ¹ is an alkylene group having 1 to 6 carbon atoms, R ² is a substituent represented by the following chemical formulas (4) to (6), R ³ is a hydroxyl group, An alkoxy group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms; ]

[In the formula (6), R ⁶ is a hydrogen atom, an aminoalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms, and R ⁷ is a hydrogen atom or an amino acid having 1 to 6 carbon atoms. It is an alkyl group. ]

  (11) The metal surface treatment method according to any one of (1) to (10), wherein the stabilizer has a reducing property, and an oxidation-reduction potential (ORP) of the metal surface treatment composition is 450 mV or less. .

  (12) Furthermore, the metal surface treatment method according to any one of (1) to (11), wherein the pH is 1.5 or more and 6.5 or less.

(13) Furthermore, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, persulfuric acid, phosphoric acid, hydrochloric acid, bromic acid, chloric acid, hydrogen peroxide, HMnO ₄ , HVO ₃ , H ₂ WO ₄ , and H ₂ MoO ₄ , and The metal surface treatment method according to any one of (1) to (12), comprising at least one oxidizing agent selected from the group consisting of these salts.

  (14) In order to form a rust-preventing film with excellent electrodeposition on the metal base material having a plurality of curved portions before the cationic electrodeposition coating, any one of (1) to (13) The metal surface treatment composition used for the metal surface treatment method of description.

  (15) The rust preventive film contains a metal element that is eluted from the metal base material and taken into the rust preventive film, and insolubilized by a stabilizer that prevents elution of metal ions from the rust preventive film, A metal material having a plurality of curved portions excellent in throwing power of an electrodeposition paint used for cationic electrodeposition coating, formed by the surface treatment method according to any one of (1) to (13).

  (16) By the metal surface treatment method according to any one of (1) to (13), a metal surface treatment step for forming a rust preventive film excellent in throwing power of the electrodeposition paint on the metal substrate; An electrodeposition coating step of electrodepositing a cationic electrodeposition coating containing a modified epoxy resin and a curing agent on the metal substrate on which the anticorrosive film is formed. Painting method.

  Since the metal surface treatment method of the present invention is a metal surface treatment method using a zirconium and / or titanium-based metal surface treatment composition that is substantially free of phosphate ions, it may give an environmental load. The surface treatment can be performed on the metal base material with little. Moreover, the said metal surface treatment method can form the rust preventive film which has the outstanding corrosion resistance on a metal base material. Furthermore, since the metal surface treatment composition used in the metal surface treatment method is added with an adhesion-imparting agent and a stabilizer that suppresses elution of components in the rust preventive coating during cationic electrodeposition coating, cationic electrodeposition coating Occasionally, when a voltage is applied, electrolyte generation due to elution of components of the rust preventive film is suppressed. As a result, there is no cause for lowering the film resistance of the anticorrosive film and the film resistance of the electrodeposition coating film, and thus excellent cationic electrodeposition coating performance is provided.

  The surface of the object to be coated may have a defective portion where a rust preventive film is not formed for some reason, but the stabilizer that suppresses the elution of the rust preventive film is adsorbed on the metal substrate of the defective portion and is dense. Corrosion resistance is improved in order to form a simple rust preventive film. Since the stabilizer further has a reducing and chelating effect, it suppresses oxidation of iron (II) ions generated in the treatment bath to iron (III) ions, and further chelates iron ions. Suppresses the formation of iron sludge in the treatment bath and improves the bath life.

  Hereinafter, embodiments of the present invention will be described in detail.

<< Metallic surface treatment method >>
In the present embodiment, the metal substrate is subjected to a surface treatment using a metal surface treatment composition containing zirconium ions and / or titanium ions, an adhesion imparting agent, and a stabilizer. The surface treatment method for performing the surface treatment of the metal substrate is not particularly limited, and can be performed by bringing a surface treatment liquid containing the metal surface treatment composition according to the present embodiment into contact with the metal substrate. That is, the surface treatment method according to the present embodiment includes a treatment liquid contact step in which a metal surface treatment liquid containing a metal surface treatment composition is contacted. As an example of the surface treatment method, an immersion method, a spray method, a roll coating method, a pouring treatment method, and the like can be given.

  Acids and bases that can be used for pH adjustment in preparing the metal surface treatment liquid are not particularly limited, but the acids include nitric acid, sulfuric acid, and organic acids, and the bases include sodium hydroxide, ammonia, and amines. Can be preferably used.

  The treatment temperature in the surface treatment is preferably in the range of 20 ° C. or more and 70 ° C. or less, and more preferably in the range of 30 ° C. or more and 50 ° C. or less. If it is less than 20 ° C., there is a possibility that sufficient film formation may not be performed, and there is a disadvantage that it is necessary to adjust the temperature by introducing a cooling device or the like in the summer. It is only economically disadvantageous.

  The treatment time in the surface treatment is preferably in the range of 2 seconds to 1100 seconds, more preferably in the range of 30 seconds to 120 seconds. If it is less than 2 seconds, it is inconvenient because a sufficient amount of film cannot be obtained, and if it exceeds 1100 seconds, it is meaningless because an effect cannot be obtained even if the amount of film is further increased.

<Metallic surface treatment composition>
The metal surface treatment composition used in the metal surface treatment method according to the present embodiment is a metal surface treatment composition used when forming a rust preventive film on a metal substrate for applying cationic electrodeposition coating, Zirconium ions and / or titanium ions, an adhesion-imparting agent, and a stabilizer that suppresses elution of components in the rust-preventive coating during cationic electrodeposition coating. In addition, the metal surface treatment composition according to the present embodiment may include free fluorine ions, an oxidizing agent, an additive, and the like as necessary. The metal surface treatment composition according to this embodiment can act as a throwing power improver. The adhesion-imparting agent is an essential component for obtaining an excellent rust preventive film, but depending on the application, there may be a case where a high degree of rust preventive ability is not required. In such a case, since the problem of throwing power with electrodeposition is mainly solved by a stabilizer, the metal surface treatment composition of the present embodiment does not include the adhesion-imparting agent at all in order to reduce the cost. It does not have to be included.

[Zirconium ions and / or titanium ions]
Zirconium ions and / or titanium ions contained in the metal surface treatment composition are rust preventive film forming components. By forming a rust preventive film containing zirconium and / or titanium on the metal substrate, the corrosion resistance and wear resistance of the metal substrate can be improved.

  Although it does not specifically limit as a supply source of a zirconium ion, For example, fluoride zirconate; salt of fluoride zirconate, such as potassium fluoride zirconate and ammonium fluoride zirconate; zirconium fluoride; zirconium oxide; Zirconium oxide colloid; zirconyl nitrate; and zirconium carbonate.

  Although it does not specifically limit as a supply source of a titanium ion, For example, Fluorotitanic acid; Salts of fluorinated titanic acids, such as potassium fluoride titanate and ammonium fluoride titanate; Titanium fluoride; Titanium oxide; And titanium alkoxide.

  The total content of zirconium ions and / or titanium ions in the metal surface treatment composition according to this embodiment is preferably in the range of 10 ppm to 10000 ppm in terms of metal element, and is in the range of 50 ppm to 5000 ppm. More preferably. If it is less than 10 ppm, a sufficient rust preventive film cannot be obtained on the metal substrate. On the other hand, if it exceeds 10,000 ppm, no further effect can be expected, which is economically disadvantageous.

[Adhesion imparting agent]
The metal surface treatment composition according to this embodiment further contains an adhesion promoter. The adhesion imparting agent is at least one selected from the group consisting of (A) silicon-containing compounds, (B) adhesion imparting metal ions, and (C) adhesion imparting resins. By containing these compounds, the adhesion of the coating film and the corrosion resistance after coating are remarkably improved.

((A) silicon-containing compound)
The (A) silicon-containing compound is not particularly limited and includes, for example, silica such as water-dispersible silica; silicofluorides such as silicic hydrofluoric acid, ammonium silicofluoride, and sodium silicofluoride; sodium silicate, potassium silicate, and silicic acid. Water-soluble silicate compounds such as lithium acid; silicic acid esters; alkyl silicates such as diethyl silicate; and silane coupling agents. The content of the silicon-containing compound in the metal surface treatment composition is preferably 1 ppm to 5000 ppm, and more preferably 20 ppm to 2000 ppm. When the content of the silicon-containing compound is less than 1 ppm, the corrosion resistance of the resulting rust preventive film is lowered, which is not preferable. If it exceeds 5000 ppm, further improvement in the effect cannot be expected, which is economically disadvantageous, and the adhesion after coating may be reduced.

(silica)
Although it does not specifically limit as a silica, Since water dispersibility in a metal surface treatment composition is high, a water dispersible silica can be used preferably. The water-dispersible silica is not particularly limited, and examples thereof include spherical silica, chain silica, and aluminum-modified silica that are low in impurities such as sodium. The spherical silica is not particularly limited. For example, “Snowtex N”, “Snowtex O”, “Snowtex OXS”, “Snowtex UP”, “Snowtex XS”, “Snowtex AK”, “Snow” Colloidal silica such as “Tex OUP”, “Snowtex C”, and “Snowtex OL” (both trade names, manufactured by Nissan Chemical Industries, Ltd.), “Aerogel” (trade name, manufactured by Nippon Aerogel Co., Ltd.), etc. Examples thereof include fumed silica. The chain silica is not particularly limited. For example, “Snowtex PS-M”, “Snowtex PS-MO”, “Snowtex PS-SO” (all trade names, manufactured by Nissan Chemical Industries, Ltd.), etc. Examples thereof include silica sols. Examples of the aluminum-modified silica include commercially available silica sols such as “Adelite AT-20A” (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.). The silicon-containing compound may be used alone, but exhibits an excellent effect when used in combination with (B) an adhesion-imparting metal ion and / or (C) an adhesion-imparting resin.

(Silane coupling agent)
The silane coupling agent is particularly preferably an aminosilane having at least one amino group in one molecule. The aminosilane may be either a hydrolysis polycondensate containing a monomer or a dimer, but the hydrolysis polycondensation product of aminosilane is preferred from the viewpoint that it can be washed with water before cationic electrodeposition coating.

(Aminosilane)
Since aminosilane having at least one amino group in one molecule has an amino group, it is considered that it contributes to improvement in adhesion when incorporated in a rust preventive film. Specific examples of the aminosilane having at least one amino group in one molecule include N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and N- (2-aminoethyl) -3-aminopropyltrimethoxy. Silane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl- Butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, and the like. Since these compounds are excellent in adsorption to a metal substrate and adhesion to an electrodeposition coating film, the corrosion resistance after coating is improved. Commercially available amino group-containing silane coupling agents "KBM-403", "KBM-602", "KBM-603", "KBE-603", "KBM-903", "KBE-903", ""KBE-9103","KBM-573","KBP-90" (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.), "XS1003" (trade names, manufactured by Chisso Corporation) and the like can be used.

(Aminosilane hydrolysis polycondensate)
The metal surface treatment composition according to the present embodiment may contain a hydrolyzed polycondensate of aminosilane. Since the hydrolyzed polycondensate of aminosilane acts on both the surface of the metal substrate and the coating film formed thereafter, the adhesion between them can be improved. The molecular weight of the hydrolyzed polycondensate of aminosilane is not particularly limited, but a higher molecular weight is preferable because it tends to be incorporated into a hydroxide or oxide of zirconium and / or titanium. For this reason, when making aminosilane react by hydrolysis polycondensation reaction, it is preferable to make it react on conditions on which aminosilane is more easily hydrolyzed and polycondensed. Conditions under which aminosilane is more easily hydrolyzed and more easily polycondensed include, for example, reaction conditions in which the solvent is an aqueous solvent containing a catalyst such as alcohol and acetic acid, and co-condensation rather than single condensation as described above. Reaction conditions depending on the aminosilane composition. Further, by reacting under a condition where the aminosilane concentration is relatively high, a hydrolyzed polycondensate can be obtained under a higher molecular weight and higher polycondensation rate. Specifically, it is preferable to perform polycondensation when the aminosilane concentration is in the range of 5 mass% to 50 mass%.

(Total content of aminosilane and / or hydrolyzed polycondensate of aminosilane)
The total content of aminosilane and / or hydrolyzed polycondensate of aminosilane is preferably 1 ppm or more and 2000 ppm or less, more preferably 10 ppm or more and 200 ppm or less in terms of silicon element. When the total content is less than 1 ppm, the adhesiveness is lowered, and when the total content exceeds 2000 ppm, no further effect can be expected, which is economically disadvantageous.

(Mass ratio of zirconium element and / or titanium element to silicon element contained in aminosilane and / or aminosilane hydrolysis polycondensate)
The mass ratio of zirconium element and / or titanium element contained in the metal surface treatment composition with respect to silicon element contained in aminosilane and / or aminosilane hydrolysis condensate is preferably 0.5 or more and 500 or less. When the mass ratio is less than 0.5, the formation of a rust preventive film with zirconium and / or titanium is hindered, so that the adhesion and corrosion resistance are lowered. When the mass ratio exceeds 500, the aminosilane and / or aminosilanized hydrolyzed polycondensate is not sufficiently taken into the rust preventive film, so that sufficient adhesion cannot be ensured.

((B) adhesion imparting metal ion)
By adding (B) adhesion imparting metal ions to the metal surface treatment composition according to this embodiment, the corrosion resistance and adhesion of the rust preventive film can be improved. Examples of the adhesion-imparting metal ions include at least one selected from the group consisting of magnesium, zinc, calcium, aluminum, gallium, indium, copper, iron, manganese, nickel, cobalt, and silver. Among these, aluminum ions are preferable because they can further improve the corrosion resistance and adhesion of the anticorrosive film. The content of the adhesion imparting metal ion in the metal surface treatment composition is preferably 1 ppm to 5000 ppm, more preferably 20 ppm to 2000 ppm. If it is less than 1 pp, the corrosion resistance of the resulting rust-preventing film is lowered, which is not preferable. If it exceeds 5000 ppm, no further improvement in the effect is observed, which is economically disadvantageous, and the adhesion may decrease after coating.

((C) adhesion imparting resin)
(C) The adhesion imparting resin is at least one selected from the group consisting of a polyamine compound, a blocked isocyanate compound, and a melamine resin. By containing these compounds, the adhesion of the coating film is remarkably improved. The content of the adhesion imparting resin in the metal surface treatment composition is preferably 1 ppm or more and 5000 ppm or less, and more preferably 20 ppm or more and 2000 ppm or less. If it is less than 1 ppm, the corrosion resistance of the resulting rust-preventing film is lowered, which is not preferable. If it exceeds 5000 ppm, no further effect is observed, which is economically disadvantageous, and the adhesion after coating may be reduced.

(Polyamine compound)
The polyamine compound contained in the metal surface treatment composition according to this embodiment is a polymer compound having a plurality of amino groups (preferably primary amino groups) in one molecule. Since this polyamine compound containing an amino group acts on both a rust preventive film and a coating film formed thereafter, the adhesion between them can be improved. The molecular weight of the polyamine compound is not particularly limited, but is preferably 150 or more and 500000 or less, and more preferably 5000 or more and 70000 or less. When the molecular weight is less than 150, a rust preventive film having sufficient coating film adhesion cannot be obtained, which is not preferable. If the molecular weight exceeds 500,000, film formation may be hindered.

［式（３）中、Ｒ^１は炭素数１から６のアルキレン基であり、Ｒ^２は下記化学式（４）から（６）で表される置換基であり、Ｒ^３はヒドロキシル基、炭素数１から６のアルコキシ基、又は、炭素数１から６のアルキル基である。］

［式（６）中、Ｒ^６は水素原子、炭素数１から６のアミノアルキル基、又は炭素数１から６のアルキル基であり、Ｒ^７は、水素原子、又は炭素数１から６のアミノアルキル基である。］ (Structural formula of polyamine compound)
An example of the polyamine compound is a polyamine compound having the following structure. That is, this polyamine compound is a compound having at least one of structural units represented by the following chemical formulas (1), (2), and (3).

[In the formula (3), R ¹ is an alkylene group having 1 to 6 carbon atoms, R ² is a substituent represented by the following chemical formulas (4) to (6), R ³ is a hydroxyl group, An alkoxy group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms; ]

[In the formula (6), R ⁶ is a hydrogen atom, an aminoalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms, and R ⁷ is a hydrogen atom or an amino acid having 1 to 6 carbon atoms. It is an alkyl group. ]

  The polyamine compound is excellent in the effect of improving the adhesiveness, and is therefore a polyvinylamine resin composed of the structural unit represented by the chemical formula (1), and a polyallylamine composed of the structural unit represented by the chemical formula (2). A polysiloxane composed of a resin and a structural unit represented by the chemical formula (3) is preferable. Examples of polysiloxanes include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl)- 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3- Mention may be made of aminopropyltrimethoxysilane and hydrolysis polycondensates of N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, and salts thereof.

  The polyvinylamine resin is not particularly limited, and for example, a commercially available polyvinylamine resin such as “PVAM-0595B” (trade name, manufactured by Mitsubishi Chemical Corporation) can be used. The polyallylamine resin is not particularly limited, and examples thereof include “PAA-01”, “PAA-10C”, “PAA-H-10C”, and “PAA-D-41HCl” (all trade names, Nittobo Co., Ltd.). Commercially available polyallylamine resin such as (manufactured) can be used. Moreover, you may use 2 or more types together among polyvinylamine resin, polyallylamine resin, and polysiloxane.

  The ratio of the content of zirconium element and / or titanium element to the mass of the polyamine compound is preferably from 0.1 to 100, and more preferably from 0.5 to 20. When the content ratio is less than 0.1, sufficient corrosion resistance and adhesion cannot be obtained. If the content ratio exceeds 100, cracks are likely to occur in the rust preventive film, making it difficult to obtain a uniform film.

(Blocked isocyanate compound)
The blocked isocyanate compound is not particularly limited, but is a tolylene diisocyanate blocked with a blocking agent such as phenol, alcohol, oxime, active methylene, acid amide, carbamate, and sulfite. Isomers; aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate; araliphatic diisocyanates such as xylylene diisocyanate; isophorone diisocyanate; and alicyclic diisocyanates such as 4,4′-dicyclohexylmethane diisocyanate; And aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate.

(Melamine resin)
Specific examples of the melamine resin include a methyl ether type having a methoxy group, “Cymel 303”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 370”, and “Cymel 385” (all Trade name, manufactured by Mitsui Cyanamid Co., Ltd.), "Summar M40S", "Summar M50S", and "Summar M100" (all trade names, manufactured by Sumitomo Chemical Co., Ltd.). Examples of the butyl ether type having a butoxy group include “Uban 20SE60”, “Uban 20SE125”, and “Uban 20SE128” (all trade names, manufactured by Mitsui Toatsu Chemical Co., Ltd.), “Super Becamine G821”, and “Super Becamine J820” (all trade names, manufactured by Dainippon Ink & Chemicals, Inc.), “My Coat 506”, “My Coat 508” (all trade names, manufactured by Mitsui Cyanamid Co., Ltd.), etc. It is done. Furthermore, as the mixed ether type melamine, “Cymel 325”, “Cymel 328”, “Cymel 254”, “Cymel 266”, “Cymel 267”, “Cymel 285”, and “Cymel 1141” (all trade names are Mitsui). Cyanamid Co., Ltd.), “Nicarak MX-40”, “Nicarak MX-45” (both trade names, manufactured by Mitsui Chemicals, Inc.) and the like.

  As the adhesion-imparting agent, it is preferable to use (A) a silicon-containing compound, and it is particularly preferable from the viewpoint of performance to use (A) a silicon-containing compound and (B) an adhesion-imparting metal ion. Preferred (A) silicon-containing compounds are silane coupling agents, and aminosilane hydrolyzed polycondensates are particularly preferred. Moreover, as (B) adhesion imparting metal ions used in combination when (A) a silicon-containing compound is used as the adhesion imparting agent, aluminum ions are preferable. That is, as the adhesion-imparting agent, a combination of (A) a silane coupling agent as a silicon-containing compound and (B) an aluminum ion as an adhesion-imparting metal ion is preferable. A combination of the condensate and (B) an aluminum ion as the adhesion-imparting metal ion is particularly preferable. A film made of aluminum is formed even on a portion where a rust preventive film made of zirconium is not formed due to the presence of aluminum ions, and a plurality of amino groups of aminosilane hydrolysis polycondensate are present in the film. Excellent coating film adhesion is obtained.

[Stabilizer]
The metal surface treatment composition according to the present embodiment contains a stabilizer that suppresses elution of components in the rust preventive coating during cationic electrodeposition coating. As described above, the film resistance of the rust preventive film obtained by treatment with a zirconium-based and / or titanium-based surface treatment composition is smaller than that of a conventionally known zinc phosphate-based film. In addition, when a cationic electrodeposition coating is applied to a metal substrate on which a rust-preventive film containing zirconium and / or titanium is formed, the components in the rust-preventive film are present under alkaline conditions in the vicinity of the metal substrate that becomes the cathode. Elutes and acts as an electrolyte. Since this electrolyte tends to permeate into the electrodeposition coating film, the coating resistance of the electrodeposition coating film is lowered, and the throwing power of the electrodeposition coating is remarkably reduced. The stabilizer suppresses the elution of the rust preventive film component, and adsorbs to the defective part of the rust preventive film (the part where the metal substrate is exposed), thereby increasing the corrosion resistance of the film and improving the corrosion resistance. Since the stabilizer further has a chelating power, for example, iron (II) ions are stabilized, the generation of sludge such as iron oxide is suppressed, and the life of the treatment bath is consequently increased.

  In order to prevent a decrease in coating resistance of the electrodeposition coating film due to the formation of electrolyte during electrodeposition coating, the metal surface treatment composition according to the present embodiment captures the eluted ions, etc., and insolubilizes or stabilizes it. Contains possible stabilizers. Specific examples of the stabilizer include at least one selected from the group consisting of hydroxy acids, amino acids, aminocarboxylic acids, aromatic acids, phosphonic acid compounds, sulfonic acid compounds, and polyvalent anions. .

  In addition, a stabilizer is added to a surface treatment composition of a commonly used zirconium and / or titanium type, and used to prepare a surface treatment composition that can improve throwing power during cationic electrodeposition coating. Also good.

(Hydroxy acid)
Hydroxy acid is a general term for carboxylic acids having both hydroxyl groups, and is sometimes called hydroxycarboxylic acid, oxyacid, alcoholic acid, or the like. In this embodiment, a water-soluble compound having at least one carboxyl group and at least one hydroxyl group in one molecule can be used. Specifically, ascorbic acid, citric acid, malonic acid, gluconic acid, tartaric acid, and lactic acid can be preferably used.

(amino acid)
As amino acids, in addition to various natural amino acids and synthetic amino acids, synthetic amino acids having at least one amino group and at least one acid group (such as a carboxyl group or a sulfonic acid group) in one molecule can be widely used. Among these, selected from the group consisting of alanine, glycine, glutamic acid, aspartic acid, histidine, phenylalanine, asparagine, arginine, glutamine, cysteine, leucine, lysine, proline, serine, tryptophan, valine, and tyrosine, and salts thereof. At least one can be preferably used. In addition, when an amino acid has an optical isomer, any of L-form, D-form, and racemate can be suitably used.

(Aminocarboxylic acid)
As aminocarboxylic acids, compounds having both amino group and carboxyl group functional groups in one molecule other than the above amino acids can be widely used. Among these, diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraaminehexaacetic acid (TTHA), 1,3-propanediaminetetraacetic acid (PDTA), 1,3-diamino-6-hydroxy Propane 4 acetic acid (DPTA-OH), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethyl glycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA), dicarboxymethyl glutamic acid (CMGA), and (S, S) -ethylenediamine At least one selected from the group consisting of disuccinic acid (EDDS) and salts thereof can be preferably used. Further, ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) can be used. However, since they are toxic and have low biodegradability, careful attention is required when used. It should be noted that nitrilotriacetic acid sodium salt, which is a sodium salt of NTA, can be suitably used because it is considered that the above problems are few.

(Aromatic acid)
Specific examples of the aromatic acid include phenolic compounds containing at least one phenolic hydroxyl group in one molecule. Examples of the phenolic compound include compounds having two or more phenolic hydroxyl groups such as catechol, gallic acid, pyrogallol, and tannic acid, or phenolic compounds having these as a basic skeleton (for example, flavonoids, tannins, and catechins). Examples include polyphenol compounds, polyvinylphenol, water-soluble resols, novolac resins, and lignin. Among these, tannin, gallic acid, catechin, and pyrogallol are particularly preferable. The flavonoid is not particularly limited, and examples thereof include flavone, isoflavone, flavonol, flavanone, flavanol, anthocyanidin, aurone, chalcone, epigallocatechin gallate, gallocatechin, theaflavin, soybean in, genistin, rutin, and myricitrin.

(Phosphonic acid compound)
Examples of phosphonic acid compounds include 1-hydroxyethylidene-1,1-diphosphonic acid-2-phosphobutanone-1,2,4-tricarboxylic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), and 2- Organic phosphonic acid compounds such as phosphobutanone-1,2,4-tricarboxylic acid are preferably used. The phosphonic acid compounds may be used alone or in combination.

(Sulfonic acid compound)
As the sulfonic acid, at least one selected from the group consisting of metasulfonic acid, isethisulfonic acid, taurine, naphthalene disulfonic acid, amino naphthalene disulfonic acid, sulfosalicylic acid, naphthalene sulfonic acid formaldehyde condensate, alkyl naphthalene sulfonic acid, and salts thereof Can be used.

  When a sulfonic acid compound is used, the paintability and corrosion resistance of the metal substrate after the surface treatment can be improved. The mechanism is not clear, but there are two possible reasons.

  First, silica segregated material or the like is present on the surface of a metal substrate such as a steel plate, and the surface composition is non-uniform, so that there are portions that are difficult to be etched in the surface treatment. However, it is presumed that by adding a sulfonic acid compound, such a portion that is difficult to be etched can be etched, and as a result, a uniform rust preventive film is easily formed on the surface of the object to be coated. That is, it is assumed that the sulfonic acid compound acts as an etching accelerator.

  The other is that during the surface treatment, hydrogen gas that may be generated by the chemical conversion reaction may interfere with the reaction at the interface, and the sulfonic acid compound removes the hydrogen gas as a depolarization action and promotes the reaction. Presumed to be.

  Of these sulfonic acid compounds, taurine is preferred because it has both an amino group and a sulfone group. The content of the sulfonic acid compound is preferably 0.1 ppm or more and 10,000 ppm or less, and more preferably 1 ppm or more and 1000 ppm or less. If the content is less than 0.1 ppm, the effect of adding the sulfonic acid compound cannot be sufficiently obtained, and if it exceeds 10,000 ppm, precipitation of zirconium and / or titanium may be inhibited.

(Multivalent anion)
The polyvalent anion is not particularly limited, and for example, at least one selected from the group consisting of phosphoric acid, condensed phosphoric acid, phosphonic acid, lignin, tannins, phenolic compounds, polyacrylic acid, and saccharides. Can be used. Among these, examples of tannins include gallotannin, ellagitannin, and catechin, and examples of saccharides include glucose, maltose, and fructose. Among the above polyvalent anions, condensed phosphoric acid, polyacrylic acid, and catechin are preferably used.

  As the stabilizer, the throwing power can be improved by using any of the above hydroxy acid, amino acid, aminocarboxylic acid, aromatic acid, phosphonic acid compound, sulfonic acid compound, and polyvalent anion. In a mode using only hydroxy acids such as citric acid, gluconic acid and ascorbic acid known as chelating agents as stabilizers, it is difficult to satisfy both throwing power and corrosion resistance. It is preferable to use one or more of amino acids, aminocarboxylic acids, aromatic acids, phosphonic acid compounds, sulfonic acid compounds, and polyvalent anions.

  Among these, as the stabilizer, amino acids, aminocarboxylic acids, and sulfonic acid compounds are used as stabilizers in that they have excellent effects of improving throwing power and corrosion resistance when the silicon-containing compound (A) is used as the adhesion-imparting agent. Any one or two or more of these are preferably used, and sulfonic acid compounds that are particularly excellent in the effect of improving throwing power and corrosion resistance are particularly preferable.

  In addition, when (A) a silicon-containing compound and (B) an adhesion-imparting metal ion are used in combination as the adhesion-imparting agent, any one or two of amino acids, aminocarboxylic acids, and sulfonic acid compounds are used as stabilizers. By using more than seeds, throwing power and corrosion resistance are particularly improved.

  As a combination of the adhesion-imparting agent and the stabilizer, as the adhesion-imparting agent, (A) hydrolysis polycondensate of aminosilane which is a silicon-containing compound, (B) aluminum ion of adhesion-imparting metal ion, and stability As the agent, any one or more of amino acids, aminocarboxylic acids, and sulfonic acid compounds can be used. Among these, a combination with a sulfonic acid compound is particularly preferable.

(Amount of stabilizer added)
The amount of the stabilizer added to the metal surface treatment composition according to the present embodiment is preferably in the range of 0.1 ppm to 10000 ppm, and more preferably in the range of 1 ppm to 1000 ppm. When the concentration of the stabilizer is less than 0.1 ppm, it is not preferable because the effect due to the addition of the stabilizer cannot be sufficiently obtained. When the concentration exceeds 10000 ppm, the formation of the rust preventive film is inhibited. It is not preferable.

(Reducing chelating ability of stabilizer)
The stabilizer preferably has a reducing chelating power. By having reducibility, iron (II) ions eluted in the surface treatment bath can be suppressed from being oxidized to iron (III) ions, and sludge generation can be suppressed. Further, the generated iron (III) ion is chelated and stabilized. This increases the bath life of the surface treatment bath. Examples of the stabilizer having a reducing chelating power include lactic acid, ascorbic acid, and citric acid. These stabilizers may be used independently and may use 2 or more types together.

[Free fluorine ion]
The metal surface treatment composition according to the present embodiment can further contain free fluorine ions. The free fluorine ions serve as an etching agent for the metal substrate and a complexing agent for zirconium and / or titanium. The supply source of free fluorine ions is not particularly limited, but for example, a fluoride such as hydrofluoric acid, ammonium fluoride, boron fluoride acid, ammonium hydrogen fluoride, sodium fluoride, and sodium hydrogen fluoride. Can be mentioned. It is also possible to use a complex fluoride as a supply source, for example, hexafluorosilicate, specifically, silicofluoric acid, zinc silicofluoride, manganese silicofluoride, silicohydrofluoric acid. Examples thereof include magnesium, nickel silicohydrofluoride, iron silicohydrofluorate, and calcium silicohydrofluorate.

  The free fluorine ion concentration is preferably 0.01 ppm or more and 100 ppm or less, more preferably 0.1 ppm or more and 20 ppm or less when measured with a fluorine ion sensitive electrode. If the concentration of the free fluorine ions is less than 0.01 ppm, there is a possibility that the composition becomes unstable and precipitates are formed, and the etching power is lowered, and there is a possibility that the film is not sufficiently formed. On the other hand, if the concentration of free fluorine ions exceeds 100 ppm, etching becomes excessive, and there is a possibility that the formation of the rust preventive film is not sufficiently performed.

[PH]
The pH of the metal surface treatment composition used in the present embodiment is preferably in the range of 1.5 or more and 6.5 or less, more preferably in the range of 2.0 or more and 5.5 or less, More preferably, it is in the range of 2.5 to 5.0. If the pH is less than 1.5, etching may be excessive and sufficient film formation may not be possible, or the coating amount and film thickness may be uneven, which may adversely affect the appearance of coating. On the other hand, if it exceeds 6.5, etching becomes insufficient and a good film cannot be obtained.

  In addition, pH of a metal surface treatment composition can be adjusted using basic compounds, such as acidic compounds, such as nitric acid and a sulfuric acid, and sodium hydroxide, potassium hydroxide, and ammonia.

[Oxidant]
The metal surface treatment composition according to the present embodiment can also contain an oxidizing agent for promoting the formation of a rust preventive film. Examples of the oxidizing agent that can be contained in the metal surface treatment composition include nitric acid, nitrous acid, sulfuric acid, sulfurous acid, persulfuric acid, phosphoric acid, hydrochloric acid, bromic acid, chloric acid, hydrogen peroxide, HMnO ₄ , HVO ₃ , H ₂ WO _4, and _H 2 MoO _4, and can include at least one selected from the group consisting of salts.

<Metal base material>
Although it does not specifically limit as a metal base material used in the surface treatment method which concerns on this embodiment, For example, an iron-type metal base material, an aluminum-type metal base material, a zinc-type metal base material, etc. are mentioned. Can do.

  In addition, the surface treatment method according to the present embodiment is a combination of a plurality of types of metal substrates such as an iron-based metal substrate, an aluminum-based metal substrate, and a zinc-based metal substrate (joint portions and contact portions between different metals). It is also possible to apply to a metal substrate made of In particular, automobile bodies and parts for automobiles are composed of various metal substrates such as iron, zinc, and aluminum. However, according to the metal surface treatment method of this embodiment, sufficient substrate concealability and adhesion are achieved. A rust-proof film having the properties can be formed, and good corrosion resistance can be imparted.

  It does not specifically limit as an iron-type metal base material used as a metal base material which concerns on this embodiment, For example, a cold-rolled steel plate, a hot-rolled steel plate, a mild steel plate, a high-tensile steel plate etc. can be mentioned. Moreover, it does not specifically limit as an aluminum-type metal base material, For example, aluminum plating steel plates, such as 5000 series aluminum alloy, 6000 series aluminum alloy, and aluminum-type electroplating, hot dipping, vapor deposition plating, etc. are mentioned. Can do. In addition, the zinc-based metal substrate is not particularly limited, and examples thereof include zinc-based electrical materials such as galvanized steel sheets, zinc-nickel plated steel sheets, zinc-titanium plated steel sheets, zinc-magnesium plated steel sheets, and zinc-manganese plated steel sheets. Examples thereof include zinc, zinc-based alloy-plated steel sheets, and the like such as plating, hot dipping, and vapor-deposited steel sheets. There are various grades of high-strength steel sheets depending on strength and manufacturing method, and examples include JSC400J, JSC440P, JSC440W, JSC590R, JSC590T, JSC590Y, JSC780T, JSC780Y, JSC980Y, and JSC1180Y.

<Rust prevention film amount>
In the case of an iron-based metal substrate, the coating amount of the antirust coating formed by the surface treatment method according to this embodiment is preferably 10 mg / m ² or more in terms of metal elements of zirconium and / or titanium, and 20 mg / M ² or more is more preferable, and 30 mg / m ² or more is still more preferable. When the coating amount of the rust preventive coating is less than 10 mg / m ² , sufficient corrosion resistance cannot be obtained.

In any metal material, there is no particular upper limit to the coating amount of the rust preventive coating, but if the coating amount is too large, cracks are likely to occur in the rust preventive coating, making it difficult to obtain a uniform coating. In this respect, the coating amount of the rust preventive coating formed by the metal surface treatment method of the present embodiment is preferably 1 g / m ² or less in terms of metal elements of zirconium and / or titanium, and is 800 mg / m ² or less. More preferably.

<Metal material>
The metal material formed by forming a rust preventive film on a metal substrate by the surface treatment method according to the present embodiment contains a compound containing a metal element eluted from the metal substrate during the surface treatment in the rust preventive film. ing. This compound containing a metal element is insolubilized by the action of a stabilizer contained in the metal surface treatment composition, and has a structure that does not elute metal ions even in an alkaline environment during cationic electrodeposition coating. For this reason, when the cationic electrodeposition coating is performed using the metal material of the present embodiment, the electric resistance value of the rust preventive film does not decrease, so that the coating film can be formed uniformly and the throwing power is improved. be able to.

<< Cationic electrodeposition coating >>
<Cationic electrodeposition paint>
As the cationic electrodeposition coating that can be used in the cationic electrodeposition coating, conventionally known ones can be used and are not particularly limited, but modified epoxy such as aminated epoxy resin, aminated acrylic resin, and sulfoniumated epoxy resin. A known cationic electrodeposition paint containing a resin, a curing agent, and a sealing agent can be applied.

  It does not specifically limit as a modified | denatured epoxy resin which concerns on this embodiment, A conventionally well-known thing can be used. Preferably, an amine-modified epoxy resin and an oxazolidone ring-containing epoxy resin produced by opening an epoxy ring of a bisphenol-type epoxy resin with an amine are used. A typical example of the bisphenol type epoxy resin which is a raw material of the modified epoxy resin is a bisphenol A type or bisphenol F type epoxy resin. As the former commercial product, “Epicoat 828” (trade name, manufactured by Yuka Shell Epoxy, epoxy equivalent 180 to 190), “Epicoat 1001” (trade name, manufactured by Yuka Shell Epoxy, epoxy equivalent 450 to 500), And “Epicoat 1010” (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent of 3000 to 4000). The latter commercially available product is “Epicoat 807” (trade name, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent of 170). ) Etc.

  The cationic electrodeposition paint of this embodiment preferably further contains a curing agent. It does not specifically limit as a hardening | curing agent, A conventionally well-known thing can be used. Preferably, a blocked isocyanate curing agent obtained by blocking polyisocyanate with a sealing agent is used. Examples of polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and 4,4′-methylenebis (cyclohexyl isocyanate); and Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate may be mentioned.

  It is preferable that the cationic electrodeposition paint of this embodiment further contains a sealant. Sealing agents include monovalent alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol carbinol, and methylphenyl carbinol; ethylene glycol monohexyl Cellosolves such as ether and ethylene glycol mono-2-ethylhexyl ether; phenols such as phenol, para-t-butylphenol, and cresol; dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, and cyclohexanone oxime And lactams represented by ε-caprolactam and γ-butyrolactam.

<Cation electrodeposition coating method>
Cationic electrodeposition coating is usually performed by applying a voltage of 50 V or more and 450 V or less between the object to be coated and the anode. When the applied voltage is less than 50V, electrodeposition is insufficient, and when it exceeds 450V, the coating film is destroyed and an abnormal appearance is obtained. The time for applying the voltage varies depending on the electrodeposition conditions, but generally it is preferably 2 minutes or more and 4 minutes or less.

  The coating film thus obtained is cured by being baked (heat treatment) as it is or after being washed with water after completion of the electrodeposition process. The baking (heat treatment) conditions are preferably 120 ° C. or higher and 260 ° C. or lower, and more preferably 140 ° C. or higher and 220 ° C. or lower. The baking (heat treatment) time is preferably 10 minutes or longer and 30 minutes or shorter.

<Management method of bath life of metal surface treatment composition>
The metal surface treatment composition of the present embodiment can increase the bath life by containing a compound having a reducing chelating power as a stabilizer. That is, when the stabilizer has a reducing chelating power, generation of sludge accompanying oxidation of iron (II) ions can be prevented, and the bath life can be increased. Such a bath life management method can be carried out by suppressing the oxidation-reduction potential (ORP) of the metal surface treatment composition to 450 mV or less. Specifically, for example, a compound such as lactic acid, ascorbic acid, and citric acid may be added so as to be 1 ppm to 10,000 ppm. The oxidation-reduction potential can be measured by an oxidation-reduction measuring instrument such as “Redox Measuring Instrument-D22” (trade name, manufactured by HORIBA, Ltd.).

<Example 1>
[Metal base material]
A commercially available cold-rolled steel sheet (SPC, Nippon Test Panel, 70 mm × 150 mm × 0.8 mm) was prepared as a metal substrate.

[Pretreatment of metal substrate]
Using “Surf Cleaner EC92” (trade name, manufactured by Nippon Paint Co., Ltd.) as an alkaline degreasing agent, the metal substrate was degreased at 40 ° C. for 2 minutes. This was immersed and washed in a water washing tank, and then spray washed with tap water for about 30 seconds.

[Preparation of metal surface treatment composition]
Zirconic acid 40% as zirconium is 500 ppm in terms of metal element, and “KBE903” (3-aminopropyl-triethoxysilane, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) as an adhesion promoter is 200 ppm in active ingredient concentration, stabilizer. HIDA was added to 200 ppm and adjusted to pH 4 with NaOH to obtain a metal surface treatment composition.
As KBE903, 5 parts by mass of KBE903 is uniformly dropped over 60 minutes from a dropping funnel into a mixed solvent of 45 parts by mass of deionized water and 50 parts by mass of ethanol (solvent temperature: 25 ° C.). Was reacted for 24 hours at 25 ° C. under a nitrogen atmosphere, and then the ethanol was evaporated by reducing the pressure of the reaction solution. The hydrolyzed polycondensate of KBE903 containing 5% active ingredient (hereinafter referred to as “KBE903 polycondensate A”). Was used.

  The ORP of the obtained metal surface treatment composition is 308 mV, the ratio of the content of zirconium element to the total content of silicon element contained in aminosilane and / or hydrolysis polycondensate of aminosilane (Zr / Si ratio) is It was 20. The surface treatment was performed at 40 ° C. for 60 seconds.

<Example 2>
“KBM603” (N-2- (aminoethyl) -3-aminopropyl-trimethoxysilane, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) as an adhesiveness imparting agent is 200 ppm in active ingredient concentration, and aspartic acid is used as a stabilizer. A metal surface treatment composition was prepared according to the method described in Example 1 except that 100 ppm was used and zirconium was used in an amount of 250 ppm in terms of metal element.

  The KBM603 is a hydrolyzed polycondensate of KBM603 (hereinafter referred to as “KBM603 polycondensate”) that has been hydrolyzed and polycondensed in advance in the same manner as in Example 1 except that KBM603 is used instead of KBE903. Used).

  The metal surface treatment composition had an ORP of 356 mV and a Zr / Si ratio of 10. The surface treatment was performed under the same conditions as described in Example 1.

<Example 3>
“PAA-H-10C” (polyallylamine resin, trade name, manufactured by Nitto Boseki Co., Ltd.) as an adhesion imparting agent is used at 50 ppm, zinc nitrate is used at 500 ppm, citric acid is used at 50 ppm as a stabilizer, and zirconium is a metal element. A metal surface treatment composition was prepared according to the method described in Example 1 except that the pH was adjusted to 3.5 using 700 ppm in terms of conversion. The ORP of the metal surface treatment composition was 295 mV. The surface treatment was performed at 35 ° C. for 90 seconds.

<Example 4>
15 parts by weight of “KBE903” (manufactured by Shin-Etsu Chemical Co., Ltd.) and 15 parts by weight of “KBE603” (N-2- (aminoethyl) -3-aminopropyltriethoxysilane, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) From a dropping funnel to 70 parts by weight of deionized water (solvent temperature: 25 ° C.) as a solvent uniformly over 60 minutes, followed by a reaction at 25 ° C. for 24 hours in a nitrogen atmosphere, A hydrolyzed polycondensate of organosilane (hereinafter referred to as “KBE903-KBE603 cocondensate”) was obtained. Example 1 except that this “KBE903-KBE603 cocondensate” was used at an active ingredient concentration of 300 ppm as an adhesion-imparting agent, 200 ppm of TTHA was used as a stabilizer, and 700 ppm of zirconium was used in terms of metal elements. A metal surface treatment composition was prepared according to the method described. The metal surface treatment composition had an ORP of 305 mV and a Zr / Si ratio of 19. The surface treatment was performed at 35 ° C. for 90 seconds.

<Example 5>
Implemented except that "KBE603" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as an adhesiveness imparting agent at an active ingredient concentration of 300 ppm, silicic acid was used at an active ingredient concentration of 50 ppm, and histidine was used as a stabilizer at 150 ppm. The metal surface treatment composition was adjusted according to the method described in Example 1. The metal surface treatment composition had an ORP of 311 mV and a Zr / Si ratio of 13. The surface treatment was performed at 40 ° C. for 90 seconds.

  The KBE 603 is a hydrolyzed polycondensate of KBE 603 previously polycondensed in the same manner as in Example 1 except that KBE 603 is used instead of KBE 903 (hereinafter referred to as “KBE 603 polycondensate”). Was used.

<Example 6>
Except for using 30 ppm of "PAA-H-10C" (polyallylamine resin, trade name, manufactured by Nitto Boseki Co., Ltd.) as an adhesion-imparting agent, 200 ppm of DTPA as a stabilizer, and 250 ppm of zirconium in terms of metal element. In accordance with the method described in Example 1, a metal surface treatment composition was prepared. The ORP of the metal surface treatment composition was 290 mV. The surface treatment was performed at 40 ° C. for 90 seconds.

<Example 7>
“KBE903 polycondensate A” is used at 150 ppm in terms of active ingredient concentration as an adhesion-imparting agent, “Hishicolin THPS” (phosphonium, trade name, manufactured by Nippon Chemical Industry Co., Ltd.) is used as a stabilizer at 100 ppm, and zirconium is converted into a metal element. A metal surface treatment composition was prepared according to the method described in Example 1 except that 250 ppm was used. The Zr / Si ratio was 13. The surface treatment was performed at 40 ° C. for 90 seconds.

<Example 8>
30 parts by weight of “KBE903” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is uniformly added from a dropping funnel to a mixed solvent of 35 parts by weight of deionized water and 35 parts by weight of isopropyl alcohol (solvent temperature: 25 ° C.) over 60 minutes. It was dripped in. This was reacted at 25 ° C. for 24 hours under a nitrogen atmosphere. Thereafter, the reaction solution was depressurized to evaporate isopropyl alcohol to obtain an organosilane hydrolyzed polycondensate (hereinafter referred to as “KBE903 polycondensate B”) having an active ingredient of 30%. As an adhesion-imparting agent, a metal surface treatment composition was prepared according to the method described in Example 1, except that this KBE903 polycondensate was used at an active ingredient concentration of 150 ppm and gallic acid 100 ppm was used as a stabilizer. went. The Zr / Si ratio was 43.

<Example 9>
“PAA-H-10C” (polyallylamine resin, trade name, manufactured by Nitto Boseki Co., Ltd.) is used at 50 ppm as an adhesion promoter, and “PO40” (reducing sugar, trade name, manufactured by Towa Kasei Kogyo Co., Ltd.) is used as a stabilizer. A metal surface treatment composition was prepared according to the method described in Example 1 except that 200 ppm was used and that 700 ppm zirconium was used in terms of metal element. The surface treatment was performed at 40 ° C. for 90 seconds.

<Example 10>
The method described in Example 1 except that “colloidal silica OXS” (colloidal silica, trade name, manufactured by Nissan Chemical Industries, Ltd.) was used at an active ingredient concentration of 200 ppm, and tyrosine was used at 200 ppm as a stabilizer. The metal surface treatment composition was prepared according to the above. The surface treatment was performed under the same conditions as described in Example 1.

<Example 11>
“KBE903 polycondensate A” is used as an adhesion-imparting agent at 200 ppm, magnesium nitrate is used at 500 ppm, sodium salt of NTA is used as a stabilizer at 150 ppm, and zirconium is used at 250 ppm in terms of a metal element, and the pH is 3.5. A metal surface treatment composition was prepared according to the method described in Example 1 except that the point was adjusted to. The Zr / Si ratio was 10. The surface treatment was performed under the same conditions as described in Example 1.

<Example 12>
Mixing of 15 parts by weight of “KBE903” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), 15 parts by weight of “KBE603” (product name, manufactured by Shin-Etsu Chemical Co., Ltd.), 35 parts by weight of deionized water and 35 parts by weight of ethanol After dropping uniformly into a solvent (solvent temperature: 25 ° C.) with a dropping funnel over 60 minutes, the mixture was reacted at 25 ° C. for 24 hours in a nitrogen atmosphere. Thereafter, the reaction solution was depressurized to evaporate isopropyl alcohol to obtain an organosilane hydrolysis polycondensate (hereinafter referred to as “KBE903-KBE603 cocondensate B”) having an active ingredient of 30%. This "KBE903-KBE603 cocondensate B" is used as an adhesion-imparting agent in an active ingredient concentration of 200 ppm, aluminum hydroxide 500 ppm, hydrofluoric acid 1100 ppm, glycine 100 ppm, and zirconium as a metal. A metal surface treatment composition was prepared according to the method described in Example 1 except that 700 ppm was used in terms of element. The Zr / Si ratio was 28. The surface treatment was performed under the same conditions as described in Example 1.

<Example 13>
As zirconium, zircon hydrofluoric acid was used at 250 ppm in terms of metal element, modified polyallylamine was used as an adhesion-imparting agent at 50 ppm, HEDTA was used at 150 ppm as a stabilizer, and sodium nitrite was used as an additive at 100 ppm, with a pH of 3 A metal surface treatment composition was prepared according to the method described in Example 1 except that the amount was adjusted to .5. The surface treatment was performed under the same conditions as described in Example 1.

  The modified polyallylamine is 1% by weight of “PAA10C” (polyallylamine, effective concentration 10%, trade name, manufactured by Nitto Boseki Co., Ltd.) and “KBM403” (3-glycidoxypropyl- Trimethoxysilane, effective concentration 100%, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed at a weight ratio of 1: 0.5, and the mixture was reacted at a reaction temperature of 25 ° C. and a reaction time of 60 minutes.

<Example 14>
"KBE903 polycondensate A" is used as an adhesion-imparting agent at an active ingredient concentration of 200 ppm, lactic acid is used as a stabilizer at 100 ppm, polyhexamethylene biguanidine acetate (biguanide) is used as an additive at 100 ppm, and zirconium is metal A metal surface treatment composition was prepared according to the method described in Example 1 except that 700 ppm was used in terms of element. The Zr / Si ratio was 28. The surface treatment was performed under the same conditions as described in Example 1.

<Example 15>
The method described in Example 1 except that “KBE903 polycondensate B” was used as an adhesion promoter at an active ingredient concentration of 150 ppm, phenylalanine was used as a stabilizer at 150 ppm, and ascorbic acid was used as an additive at 100 ppm. According to the above, a metal surface treatment composition was prepared. The Zr / Si ratio was 27. The surface treatment was performed under the same conditions as described in Example 1.

<Example 16>
Except for using “KBE903 polycondensate A” as an adhesiveness imparting agent in an active ingredient concentration of 150 ppm, 200 ppm of methanesulfonic acid as a stabilizer, 200 ppm of aluminum ions as an additive, and 250 ppm of zirconium in terms of metal elements, According to the method described in Example 1, a metal surface treatment composition was prepared. The Zr / Si ratio was 13. The surface treatment was performed under the same conditions as described in Example 1. Note that aluminum nitrate was used as a supply source of aluminum ions.

<Example 17>
Except for adjusting the pH to 3.5 using “KBE603 polycondensate A” as an adhesiveness imparting agent at an active ingredient concentration of 200 ppm, using citric acid as a stabilizer at 50 ppm, zirconium as a metal element in terms of 700 ppm, and According to the method described in Example 1, a metal surface treatment composition was prepared. The surface treatment was performed at 35 ° C. for 90 seconds.

<Comparative Example 1>
A metal surface treatment composition was prepared according to the method described in Example 1 except that the stabilizer was not used. The ORP was 459 mV and the Zr / Si ratio was 20. The surface treatment was performed at 40 ° C. for 90 seconds.

<Comparative example 2>
A metal surface treatment composition was prepared according to the method described in Example 1 except that the adhesion promoter and the stabilizer were not used. The surface treatment was performed at 40 ° C. for 90 seconds.

<Comparative Example 3>
According to the method described in Example 1, except that the adhesion imparting agent and the stabilizer were not used, sodium nitrite was used as an additive at 100 ppm, and zirconium was used at 250 ppm in terms of a metal element. Prepared. The ORP was 567 mV. The surface treatment was performed at 40 ° C. for 90 seconds.

<Comparative Example 4>
As described in Example 1, except that 50 ppm of “PAA-10C” (polyallylamine resin, manufactured by Nitto Boseki Co., Ltd.) was used as an adhesion-imparting agent, 100 ppm of magnesium nitrate was used as an additive, and no stabilizer was used. According to the method, the metal surface treatment composition was prepared. The surface treatment was performed at 40 ° C. for 90 seconds.

<Comparative Example 5>
The metal surface treatment composition was adjusted according to the method described in Example 1 except that zirconium was not used, 200 ppm of HIDA was used as a stabilizer, and no adhesion promoter was used. The surface treatment was performed at 40 ° C. for 90 seconds.

<Comparative Example 6 (Reference Example)>
As the surface treatment agent, a zinc phosphate surface treatment agent ("Surffine GL1 / Surfdyne 6350", trade name, manufactured by Nippon Paint Co., Ltd.) was used, and the surface treatment was performed at 35 ° C for 90 seconds. The pretreatment prior to the surface treatment was performed according to the method described in Example 1.

<Evaluation method>
(Attachment)
The throwing power was evaluated by the “four-sheet box method” described in Japanese Patent Laid-Open No. 2000-038525. That is, as shown in FIG. 1, the four metal materials subjected to the surface treatment in Examples 1 to 17 and Comparative Examples 1 to 6 are arranged in parallel with an interval of 20 mm in a standing state, and the lower and bottom surfaces of both sides A box 10 was prepared in which was sealed with an insulator such as cloth adhesive tape. The metal materials 1, 2, and 3 excluding the metal material 4 were provided with through holes 5 having a diameter of 8 mm in the lower part.

  The box 10 was immersed in an electrodeposition coating container 20 filled with a cationic electrodeposition paint. In this case, the cationic electrodeposition paint penetrates into the inside of the box 10 only from each through hole 5.

  While stirring the cationic electrodeposition paint with a magnetic stirrer, the metal materials 1 to 4 were electrically connected, and the counter electrode 21 was arranged so that the distance from the metal material 1 was 150 mm. Cathode electrodeposition coating was performed by applying a voltage using each of the metal materials 1 to 4 as a cathode and the counter electrode 21 as an anode. The coating was performed by raising the voltage to a voltage at which the film thickness of the coating film formed on the A surface of the metal material 1 reached 20 μm within 5 seconds from the start of application, and then maintaining the voltage for 175 seconds. The bath temperature at this time was adjusted to 30 ° C.

  After the metal materials 1 to 4 after painting are washed with water, they are baked at 170 ° C. for 25 minutes, and after air cooling, the film thickness of the coating film formed on the A surface of the metal material 1 closest to the counter electrode 21 and the counter electrode 21 The film thickness of the coating film formed on the G surface of the farthest metal material 4 was measured, and the throwing power was evaluated by the ratio of film thickness (G surface) / film thickness (A surface). It can be evaluated that the greater the value, the better the throwing power. The results are shown in Table 1.

(Sludge observation)
Chemical conversion treatment was carried out in Examples and Comparative Examples, and after 30 days at room temperature, turbidity (generation of sludge) in the chemical conversion treatment agent was compared visually to evaluate workability according to the following criteria. The results are shown in Table 1.
◎: Transparent liquid ○: Slightly turbid △: Turbid ×: Precipitate (sludge) generated

(Coating amount)
About the test plate obtained by the Example and the comparative example, the amount of Zr in a rust prevention film and the amount of Si were measured. The measurement was performed by fluorescent X-ray analysis. The results are shown in Table 1.

(Secondary adhesion test (SDT))
Two longitudinally parallel cuts reaching the substrate were put on the test plates obtained in Examples and Comparative Examples, and immersed in a 5% NaCl aqueous solution at 50 ° C. for 480 hours. Next, after washing with water and air drying, the adhesive tape “L-Pac LP-24” (manufactured by Nichiban Co., Ltd.) was brought into close contact with the cut portion, and the adhesive tape was peeled off rapidly. The size of the maximum width (one side) of the paint adhering to the peeled adhesive tape was measured. A similar test was performed on a galvanized steel sheet (GA) and an aluminum sheet (Al) which were surface-treated and electrodeposited. The results are shown in Table 1 (unit: mm).

(Cycle corrosion test (CCT))
The edges and back surfaces of the test plates obtained in the examples and comparative examples were tape-sealed, and a cross-cut flaw (foil reaching the metal) was inserted with a cutter, and a CCT test was performed under the following conditions.

  That is, a 5% NaCl aqueous solution kept at 35 ° C. was continuously sprayed for 2 hours in a salt spray tester kept at 35 ° C. and humidity 95%. Subsequently, it was dried for 4 hours under the conditions of 60 ° C. and humidity of 20 to 30%. This was repeated three times over 24 hours to make one cycle, and the swelling width (both sides) of the coating film was measured after 200 cycles. A similar test was performed on a galvanized steel sheet (GA) and a high-tensile steel sheet (HT) which were surface-treated and electrodeposited. The results are shown in Table 2 (unit: mm).

(SST)
35 ° C., 5% NaCl aqueous solution was continuously sprayed, the swelling width after 30 days was measured (mm), and the rust generation state of the edge portion was visually evaluated. The results are shown in Table 2.
◎: No rust ○: Almost no rust △: Rust is generated in some places ×: Many rust is generated

(Corrosion resistance)
About the test board obtained by the Example and the comparative example, the resistance value of the corrosion resistance was measured with 5% NaCl aqueous solution using "potentistat HZ-3000" (brand name, Hokuto Denko Co., Ltd. make). The results are shown in Table 2.

(Primary wet)
The test plates obtained in Examples and Comparative Examples were left for 1 hour in an atmosphere having a temperature of 50 ° C. and a humidity of 95%, and the ratio (%) of the rust area to the entire area was measured. The results are shown in Table 2.

It is a perspective view which shows an example of the box used when evaluating throwing power. It is drawing which shows typically evaluation of throwing power.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal material 2 Metal material 3 Metal material 4 Metal material 5 Through-hole 10 Box 20 Electrodeposition coating container 21 Counter electrode

Claims (16)

A metal surface treatment method for forming a rust-preventive film with excellent electrodeposition-preventing property before cationic electrodeposition coating on a metal substrate having a plurality of curved portions,
The metal surface treatment method includes:
Zirconium ions and / or titanium ions;
An adhesion-imparting agent;
A stabilizer for suppressing elution of components in the rust-preventive coating during the cationic electrodeposition coating, and a metal surface treatment composition for pretreatment of the cationic electrodeposition coating on the metal substrate. It is a metal surface treatment method characterized by forming a rust preventive film excellent in throwing power,
The adhesion imparting agent is a metal surface treatment method that is at least one selected from the group consisting of (A) a silicon-containing compound, (B) an adhesion imparting metal ion, and (C) an adhesion imparting resin.   The metal according to claim 1, wherein the stabilizer is at least one selected from the group consisting of hydroxy acids, amino acids, aminocarboxylic acids, aromatic acids, phosphonic acid compounds, sulfonic acid compounds, and polyvalent anions. Surface treatment method.   The metal surface treatment method according to claim 2, wherein the amino acid is at least one selected from the group consisting of alanine, glycine, glutamic acid, aspartic acid, histidine, phenylalanine, proline, tyrosine, and salts thereof.   The aminocarboxylic acid is diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetraaminehexaacetic acid (TTHA), 1,3-propanediaminetetraacetic acid (PDTA), 1,3-diamino- 6-hydroxypropanetetraacetic acid (DPTA-OH), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA), dicarboxymethylglutamic acid (CMGA), and (S, S The metal surface treatment method according to claim 2, which is at least one selected from the group consisting of:) -ethylenediamine disuccinic acid (EDDS).   The metal surface treatment according to claim 2, wherein the polyvalent anion is at least one selected from the group consisting of phosphoric acid, condensed phosphoric acid, phosphonic acid, lignin, tannins, phenolic compounds, polyacrylic acid, and sugars. Method.   The (A) silicon-containing compound is at least one selected from the group consisting of silica, silicofluoride, water-soluble silicate compound, silicate ester, alkyl silicate, and silane coupling agent. 5. The metal surface treatment method according to any one of 4 above. The silane coupling agent is at least one selected from the group consisting of an aminosilane having at least one amino group in one molecule and a hydrolysis polycondensate of the aminosilane,
The total content of the zirconium ions and / or titanium ions in the metal surface treatment composition is 10 ppm or more and 10,000 ppm or less in terms of metal element,
The total content of the aminosilane and / or hydrolysis polycondensate of aminosilane in the metal surface treatment composition is 1 ppm or more and 2000 ppm or less in terms of silicon element,
The ratio of the total content of zirconium element and / or titanium element to the total content of silicon element contained in the aminosilane and / or hydrolyzed polycondensate of aminosilane is 0.5 or more and 500 or less. The metal surface treatment method as described in 2.   The (B) adhesion imparting metal ion is at least one metal ion selected from the group consisting of magnesium, zinc, calcium, aluminum, gallium, indium, copper, iron, manganese, nickel, cobalt, and silver. The metal surface treatment method according to any one of 1 to 7.   The metal surface treatment method according to claim 1, wherein the (C) adhesion imparting resin is at least one selected from the group consisting of a polyamine compound, a blocked isocyanate compound, and a melamine resin. The polyamine compound is a polyamine compound having at least one selected from the group consisting of structural units represented by the following chemical formulas (1), (2), and (3) at least partially, and the mass of the polyamine compound The metal surface treatment method according to claim 9, wherein the ratio of the total content of zirconium element and / or titanium element is 0.1 to 100.

[In the formula (3), R ¹ is an alkylene group having 1 to 6 carbon atoms, R ² is a substituent represented by the following chemical formulas (4) to (6), R ³ is a hydroxyl group, An alkoxy group having 1 to 6 carbon atoms or an alkyl group having 1 to 6 carbon atoms; ]

[In the formula (6), R ⁶ is a hydrogen atom, an aminoalkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms, and R ⁷ is a hydrogen atom or an amino acid having 1 to 6 carbon atoms. It is an alkyl group. ]   11. The metal surface treatment method according to claim 1, wherein the stabilizer has a reducing property, and an oxidation-reduction potential (ORP) of the metal surface treatment composition is 450 mV or less.   Furthermore, the metal surface treatment method in any one of Claim 1 to 11 whose pH is 1.5 or more and 6.5 or less. Furthermore, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, persulfuric acid, phosphoric acid, hydrochloric acid, bromic acid, chloric acid, hydrogen peroxide, HMnO ₄ , HVO ₃ , H ₂ WO ₄ , and H ₂ MoO ₄ , and salts thereof The metal surface treatment method according to any one of claims 1 to 12, comprising at least one oxidizing agent selected from the group consisting of:   The metal surface treatment according to any one of claims 1 to 13, in order to form a rust-preventive film having excellent electrodepositing property before cationic electrodeposition coating on a metal substrate having a plurality of curved portions. Metal surface treatment composition used in the method.   The rust preventive film contains a metal element eluted from the metal base material and taken into the rust preventive film, and insolubilized by a stabilizer that prevents elution of metal ions from the rust preventive film, A metal material having a plurality of curved portions excellent in throwing power of an electrodeposition paint used for cationic electrodeposition coating, which is formed by the surface treatment method according to any one of 1 to 13. A metal surface treatment step for forming a rust preventive film having excellent throwing power of the electrodeposition paint on the metal substrate by the metal surface treatment method according to any one of claims 1 to 13,
An electrodeposition coating step of electrodepositing a cationic electrodeposition coating containing a modified epoxy resin and a curing agent on the metal substrate on which the anticorrosive film is formed. Painting method.

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