JP6172976B2 - Electrodeposition coating composition - Google Patents

Description

  The present invention relates to an electrodeposition coating composition capable of providing a cured electrodeposition coating film having excellent corrosion resistance.

  Electrodeposition coating can be applied to the details even if the workpiece has a complicated shape, and can be applied automatically and continuously, especially in large and complex shapes such as automobile bodies. It has been widely put into practical use as an undercoating method for articles to be coated. Cationic electrodeposition coating is widely used as such electrodeposition coating. Cationic electrodeposition coating is a coating method performed by immersing an object to be coated as a cathode in a cationic electrodeposition coating composition and applying a voltage.

  Before the cationic electrodeposition coating, the article to be coated is often subjected to a chemical conversion treatment such as a zinc phosphate chemical conversion treatment. By performing this chemical conversion treatment, corrosion resistance and adhesion can be improved. However, since the chemical conversion composition used in the zinc phosphate chemical conversion treatment has a high metal ion concentration and is very reactive, it is not preferable from the viewpoints of economy and workability, such as costly wastewater treatment. Further, in the chemical conversion treatment using the zinc phosphate-based chemical conversion treatment composition, water-insoluble salts are generated along with the metal surface treatment, and are deposited as precipitates in the chemical conversion treatment tank. Such precipitates are generally called sludge, and the generation of costs 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 the zinc phosphate-based chemical conversion treatment composition, it is necessary to prepare the surface in advance, and there is a problem in production efficiency that the surface treatment process becomes complicated and long.

  In place of such a zinc phosphate-based chemical conversion treatment composition, methods using a zirconium-based chemical conversion treatment composition are being studied. However, the chemical conversion film formed by the zirconium-based chemical conversion treatment composition is thinner than the chemical conversion film formed by the zinc phosphate-based chemical conversion treatment composition, so the surface current becomes non-uniform during electrodeposition. Paint appearance and throwing power will be reduced. Zirconium-based chemical conversion treatment compositions can produce less sludge than zinc phosphate-based chemical conversion treatment compositions, but sludge generation is unavoidable due to the deposition principle of forming a film by etching the coating. . For this reason, it is possible to form a cured electrodeposition coating film having better corrosion resistance, adhesion, and excellent coating appearance for the purpose of supplementing the corrosion resistance of the conversion coating formed by the zirconium-based chemical conversion treatment composition. There is a need to develop electrodeposition coating compositions that can be made.

  JP 2008-115451 A (Patent Document 1) describes a zirconium compound and, if necessary, titanium, cobalt, vanadium, tungsten, molybdenum, zinc, aluminum, bismuth, At least one metal compound (A) selected from yttrium, lanthanoid metal, alkali metal and alkaline earth metal (A) is 30 to 5,000 ppm in terms of total metal (mass conversion), and resin component (B) The film forming agent characterized by containing 1-40 mass%, surfactant (C) 0.1-10 mass%, and water is described. However, this film forming agent is different from the electrodeposition coating composition of the present invention in that the surfactant (C) is contained.

  In JP 2009-149974 (Patent Document 2), Step 1: Step of forming a chemical conversion coating (F1) by immersing a metal substrate in a chemical conversion treatment liquid that is a film forming agent (1), Step 2 A step of forming an electrodeposition coating film (F2) by electrodeposition-coating a metal substrate using the film-forming agent (2) which is the cationic electrodeposition coating composition (I) without washing with water A method of forming a film, wherein the film forming agent (1) is zirconium, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, bismuth, yttrium, iron, nickel, manganese, gallium, silver, lanthanoid metal A method for forming a multilayer film is described in which at least one metal compound component (M) comprising at least one metal (m) compound selected from the group consisting of: However, the film-forming agent (1) containing the metal compound component (M) is different from the film-forming agent (2), which is an electrodeposition paint, and is different from the electrodeposition paint composition of the present invention. The configuration of the invention is different.

Moreover, these prior art documents are immersed in an electrodeposition bath to form a passivated film, and sludge generation is unavoidable due to the reaction of the chemical conversion film that etches the object to be coated. Another problem is a decrease in paintability associated with an increase in conductivity due to eluted iron ions.

JP 2008-115451 A JP 2009-149974 A

  The present invention solves the above-mentioned conventional problems, and its object is to provide an electrodeposition coating composition capable of providing a coating film having excellent corrosion resistance and excellent coating film appearance (coating film smoothness). To provide things.

The present invention
Dissolved metal compound (A) containing one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr (provided that the dissolved metal compound (A) Except for the case of using two kinds of a dissolved metal compound (A1) in which the metal is Zn and a dissolved metal compound (A2) in which the metal is Zr), an aminated resin (B), and a curing agent (C). And an electrodeposition coating composition comprising a metal nitrite (D),
The aminated resin (B) has a number average molecular weight of 1,000 to 5,000, an amine value of 20 to 100 mgKOH / g, and a hydroxyl value of 50 to 400 mgKOH / g.
The curing agent (C) is a blocked isocyanate curing agent,
The theoretical residual hydroxyl value is 50 to 350 mgKOH / g when the aminated resin (B) and the blocked isocyanate curing agent react at the time of heat curing in the electrodeposition coating film,
An electrodeposition coating composition is provided, which solves the above problems.

The present invention also provides the following aspects:
The said soluble metal compound (A) is zinc, and ion concentration is 0.01-0.3 mass%.
The electrodeposition coating composition is further a chelating acid (which is at least one selected from the group consisting of sulfonic acid, organic phosphonic acid, organic carboxylic acid, amino acid, aminocarboxylic acid, sugar acid and carboxyl group-containing vinyl resin) Including E).
The electrodeposition coating composition further contains an aminosilane compound (F).
The electrodeposition coating composition contains a plasticizer.
The metal species of the molten metal compound is one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, and Ni.

The electrodeposition coating composition of the present invention contains a specific metal species (specifically, Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr), and is applied to the electrodeposition bath. When a voltage is applied while the coating is immersed, the resin component is deposited on the coating and it takes a short time of about 5 seconds before the resin film is formed, but the metal is deposited first on the coating. An inorganic layer is formed. That is, when electrodeposition coating is performed using the electrodeposition coating composition of the present invention, an electrodeposited film in which an inorganic layer is formed on an object to be coated and a resin film is formed as an upper layer is obtained. Thereafter, the electrodeposition coating is obtained by heat-curing the electrodeposition coating. The present invention uses the dissolved metal compound (A) containing the specific metal, and the amount of the functional group in the coating film-forming resin and the By setting the relationship with the metal content in the dissolved metal compound (A) within a specific range, an electrodeposition coating film with significantly improved rust prevention can be obtained.

  In the electrodeposition coating composition of the present invention, particularly high corrosion resistance and adhesion can be achieved particularly when zinc is used as the metal of the dissolved metal compound (A). It is considered that zinc is likely to be deposited on the object to be coated and used in combination with the metal nitrite (D), and a uniform and dense electrodeposition film is formed.

  Furthermore, there is a problem that even if electrodeposition coating is applied to an object to be coated, an electrodeposition coating film having a film thickness sufficient to obtain corrosion resistance is difficult to be formed on the edge of the object to be coated, and this part is easily corroded. However, according to the present invention, the edge portion can be coated with a sufficient film thickness, and sufficient rust prevention can be obtained. In particular, when zinc is used, the zinc is likely to be deposited on the edge portion of the coating object, and the edge portion can be covered with an inorganic layer containing zinc, and the zinc in the inorganic layer is the upper layer. It is thought that it originates in being able to maintain sufficient film thickness which is hard to be attracted by moderately hydrogen-bonding with the hydroxyl group in the resin film formed as follows.

  By using the electrodeposition coating composition of the present invention, an electrode having good corrosion resistance and adhesion can be obtained simply by performing electrodeposition coating, even if the object to be coated is not subjected to zinc phosphate conversion treatment or zirconium conversion treatment in advance. A coated film can be obtained. The coating film formed using the electrodeposition coating composition of the present invention also has an advantage of excellent coating film smoothness. By using the electrodeposition coating composition of the present invention, it is possible to eliminate the steps of zirconium chemical conversion treatment and zinc phosphate chemical conversion treatment, and reduce the cost and labor required for maintenance management associated with these chemical conversion treatments. Can do. Furthermore, since no chemical conversion treatment is performed, the problem of sludge that always occurs in the chemical conversion treatment does not occur. Needless to say, the electrodeposition coating composition of the present invention can form an effective film even on an object to be coated that has undergone zirconium chemical conversion treatment or zinc phosphate chemical conversion treatment.

The electrodeposition coating composition of the present invention comprises a step of forming an electrodeposition film by applying a voltage after immersing an object to be coated, and a step of forming an electrodeposition film by heating and curing the electrodeposition film. Including electrodeposition coating methods.

Electrodeposition Coating Composition The electrodeposition coating composition of the present invention is a dissolved metal containing one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr Compound (A) (however, as the dissolved metal compound (A), a case where two kinds of a dissolved metal compound (A1) in which the metal is Zn and a dissolved metal compound (A2) in which the metal is Zr is used) is excluded. ), An aminated resin (B), a curing agent (C), and a metal nitrite (D). Hereinafter, each component will be described in detail.

Dissolved metal compound (A)
The electrodeposition coating composition of the present invention comprises a dissolved metal compound (A) (1) containing one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr. However, the dissolved metal compound (A) includes a case where two kinds of a dissolved metal compound (A1) in which the metal is Zn and a dissolved metal compound (A2) in which the metal is Zr are used.

In the present specification, the dissolved metal compound (A) is one in which 0.1% by mass or more in terms of metal is dissolved in water at 20 ° C. adjusted to pH 4 with nitric acid. In the electrodeposition coating composition of the present invention, the dissolved metal compound (A) has the above-mentioned characteristics, so that the whole is dissolved in the electrodeposition coating composition, or a part is dissolved and the rest is dispersed. Exists. Here, dissolution refers to a state in which it is dissolved in a solvent and is uniform and a state in which it is finely dispersed. Specifically, it means a state in which precipitation does not occur when centrifugation is performed at 12,000 rpm for 30 minutes. When a part of the dissolved metal compound (A) is not dissolved but is dispersed in the electrodeposition coating composition of the present invention, the volume average particle diameter D50 is preferably 3 μm or less. Here, the volume average particle diameter D50 can be measured using a particle size measuring device such as a dynamic light scattering particle size analyzer (manufactured by Nikkiso Co., Ltd., “Nanotrack UPA150”). When the electrodeposition coating composition of the present invention contains such a dissolved metal compound (A), a cured electrodeposition coating film having excellent corrosion resistance can be obtained. In the initial stage of the electrodeposition coating process, the dissolved metal compound (A) gives adhesion to the electrodeposition coating film by forming a metal layer on the surface of the object in preference to the electrodeposition coating film. It is also taken into the coating film and improves the barrier property by improving the crosslinking density and glass transition temperature (Tg) of the coating film as an inorganic crosslinking agent during baking. For this reason, the cured electrodeposition coating film which has the outstanding corrosion resistance will be obtained.

Examples of the metal compound when the metal contained in the dissolved metal compound (A) is Ti include, for example, fluorinated titanic acid (H ₂ TiF ₆ ), ammonium titanium fluoride, and titanium sulfate. As the dissolved metal compound (A) when the metal contained in the dissolved metal compound (A) is Ti, fluorinated titanic acid is preferable.
In the dissolved metal compound (A) in the present invention, the metal component containing Ti does not include a pigment component generally used in white pigments such as titanium dioxide. The pigment component such as titanium dioxide hardly dissolves in the electrodeposition coating composition, and the condition that 0.1% by mass or more in terms of metal dissolves in 20 ° C. water adjusted to pH 4 with nitric acid described above. It is because it does not satisfy.

  Examples of the metal compound in the case where the metal contained in the dissolved metal compound (A) is Bi include, for example, bismuth hydroxide or bismuth oxide and organic materials such as lactic acid, methanesulfonic acid, DMPA (dimethylpropionic acid), or gluconic acid. Examples thereof include bismuth salts of organic acids obtained by previously mixing with an acid. When the metal contained in the dissolved metal compound (A) is Bi, the dissolved metal compound (A) is preferably bismuth lactate or bismuth salt of DMPA.

  Note that bismuth lactate, which is an example of the bismuth compound as the dissolved metal compound (A), or lactic acid and DMPA constituting the bismuth salt of DMPA are not included in the chelate acid (E) described below. This is because lactic acid and DMPA constituting the bismuth compound do not have the chelating ability required for chelating acid because they exist as counter anions of bismuth.

  Examples of the metal compound when the metal contained in the dissolved metal compound (A) is Zn include, for example, zinc oxide, zinc hydroxide, zinc acetate, zinc lactate, zinc nitrate, zinc methanesulfonate, zinc formate, and phosphoric acid. Zinc compounds such as zinc are listed. As the dissolved metal compound (A) when the metal contained in the dissolved metal compound (A) is Zn, zinc methanesulfonate and zinc oxide are preferable, and zinc methanesulfonate is particularly preferable. Since zinc methanesulfonate contains a chelating acid, it is excellent in electrodeposition paintability, and zinc oxide is excellent in electrodeposition paintability because it is difficult to increase the conductivity of the paint.

Zinc oxide, zinc hydroxide and zinc phosphate are partly dissolved as the dissolved metal compound (A) and partly present as fine particles. The volume average particle diameter D50 dispersed by the cationic dispersant is What becomes 3 micrometers or less is preferable. Here, as the cationic dispersant, for example, a dispersion resin having a cationic group, such as a modified epoxy resin having at least one kind selected from a quaternary ammonium group, a tertiary sulfonium group, and a primary amine group, and An aminosilane compound (F) etc. are mentioned. The volume average particle diameter D50 of zinc oxide, zinc hydroxide, zinc phosphate and the like dispersed with a cationic dispersant is 0.05 μm or more because the storage stability of the pigment dispersion paste is improved. preferable.

  Examples of the metal compound when the metal contained in the dissolved metal compound (A) is Zr include, for example, fluorinated zirconate; a salt of fluorinated zirconate such as potassium fluoride zirconate and ammonium fluoride zirconate; Zirconium oxide; zirconium nitrate; zirconium carbonate; zirconyl nitrate, zirconyl sulfate, zirconyl carbonate, zirconyl acetate, and the like. As the dissolved metal compound (A) when the metal contained in the dissolved metal compound (A) is Zr, fluorinated zirconic acid and zirconyl nitrate are preferable.

  Examples of metal compounds in the case where the metal contained in the dissolved metal compound (A) is Y, Nd, La, Ce, Ni, for example, oxides, hydroxides, acetates, lactic acids of Y, Nd, La, Ce Examples thereof include salts and nitrates. More preferably, Y, Nd, La, and Ce are nitrates, methanesulfonates in which oxides are dissolved with acids, and sulfamates.

The content of the dissolved metal compound (A) contained in the electrodeposition coating composition of the present invention is preferably 0.001 to 1% by mass in terms of metal element. Here, the “metal element conversion” is the metal element conversion coefficient (the coefficient for converting the metal compound amount into the metal element amount to the content of the dissolved metal compound (A), specifically, in the metal compound This is a value obtained by dividing the atomic weight of the metal element by the molecular weight of the metal compound) to obtain the target metal element amount. For example, when the dissolved metal compound (A) is a fluorinated zirconate ion, the metal element equivalent content of zirconium of the complex ion ZrF ₆ ²⁻ (molecular weight 205) 0.01% by mass is 0.01% by mass × ( It is calculated as 0.0044 mass% by calculation of 91 ÷ 205). When the content of the dissolved metal compound (A) is 0.001% by mass or more in terms of metal element, good corrosion resistance can be imparted to the article to be coated. Further, when the content of the dissolved metal compound (A) is 1% by mass or less, aggregation with the aminated resin is suppressed, and stability, corrosion resistance, and paintability are ensured. A more preferable range of the content of the dissolved metal compound (A) is 0.005 to 0.5% by mass.

When the metal of the dissolved metal compound (A) is zinc, even if it is a zinc compound that dissolves in the electrodeposition coating composition, a zinc compound that partially dissolves and partially exists as fine particles (zinc oxide, water Even in the case of zinc oxide and zinc phosphate, the ion concentration of zinc in the electrodeposition coating composition is preferably 0.01 to 0.3% by mass.

  In the electrodeposition coating composition, an organic tin curing catalyst such as dibutyltin dilaurate or dioctyltin oxide is generally used as a curing catalyst. On the other hand, since these organotin compounds have recently been regarded as problematic in toxicity and are being studied for use restrictions, it is preferable that the electrodeposition coating composition of the present invention does not contain an organotin curing catalyst. The electrodeposition coating composition of the present invention is characterized by having excellent heat-curing properties even when an organotin curing catalyst is not contained in the electrodeposition coating composition by including the dissolved metal compound (A). is there.

  The electrodeposition coating composition of the present invention preferably uses zinc (Zn) among the metal species of the dissolved metal compound (A). Zinc is a metal species that has been used for a long time. Precipitation improves when combined with a metal nitrite described later, so that an inorganic film containing uniform and dense zinc can be formed on the object to be coated. , Adhesion is also improved. In the electrodeposition coating composition of the present invention, zirconium (Zr) also has the same effect, but zirconium may have excessive interactions such as hydrogen bonding with functional groups in the coating film-forming resin. There is a problem that it is difficult to deposit on the object to be coated. Therefore, the dissolved metal compound (A) is preferably one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, and Ni. Since these metals do not excessively interact with the functional groups in the coating film-forming resin as compared with zirconium, they are favorably deposited on an object to be coated. In particular, zinc is most preferable because it has a good interaction with the functional group in the coating film-forming resin while being well deposited on the inorganic layer.

In addition, the dissolved metal compound of the present application not only forms an inorganic layer on the object to be coated, but it is inevitable that a slight amount is taken into the resin film. At this time, one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, and Ni are less likely to be mixed in the resin film as compared to zirconium. This is preferable because it hardly causes deterioration of the coating film appearance such as coating film defects due to mixing and deterioration of coating workability. In particular, zinc is most preferable because it is not easily taken into the resin film due to its moderate interaction with the functional group in the coating film-forming resin while being well deposited on the inorganic layer. On the other hand, zirconium, as described above, has a strong cohesive force and may easily become a coating film defect.

Aminated resin (B)
The electrodeposition coating composition of the present invention contains an aminated resin (B). This aminated resin (B) is a coating film forming resin constituting an electrodeposition coating film. As the aminated resin (B), a cation-modified epoxy resin obtained by modifying an oxirane ring in the resin skeleton with an organic amine compound is preferable. In general, a cation-modified epoxy resin is produced by ring-opening an oxirane ring in a starting material resin molecule by a reaction with a primary amine, a secondary amine, a tertiary amine, and / or an amine such as an acid salt thereof. A typical example of the starting material resin is a polyphenol polyglycidyl ether type epoxy resin which is a reaction product of a polycyclic phenol compound such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, cresol novolak, and epichlorohydrin. Examples of other starting material resins include oxazolidone ring-containing epoxy resins described in JP-A-5-306327. These epoxy resins can be prepared by reacting a diisocyanate compound or a bisurethane compound obtained by blocking an isocyanate group of a diisocyanate compound with a lower alcohol such as methanol or ethanol, and epichlorohydrin.

  The starting material resin can be used by extending the chain with a bifunctional polyester polyol, polyether polyol, bisphenol, dibasic carboxylic acid or the like before the ring-opening reaction of the oxirane ring with amines.

  Similarly, before the oxirane ring-opening reaction with amines, 2-ethylhexanol, nonylphenol, ethylene glycol is used for some oxirane rings for the purpose of adjusting molecular weight or amine equivalent and improving heat flow. Monohydroxy compounds such as mono-2-ethylhexyl ether, ethylene glycol mono n-butyl ether, and propylene glycol mono-2-ethylhexyl ether can also be added and used.

  Examples of amines that can be used for opening an oxirane ring and introducing an amino group include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine , N, N-dimethylbenzylamine, primary amines such as N, N-dimethylethanolamine, secondary amines or tertiary amines and / or their acid salts. Further, ketimine block primary amino group-containing secondary amine such as aminoethylethanolamine methyl isobutyl ketimine, diethylenetriamine diketimine can also be used. These amines must be reacted with at least an equivalent amount relative to the oxirane ring in order to open all the oxirane rings.

  The number average molecular weight of the aminated resin (B) is 1,000 to 5,000. When the number average molecular weight is 1,000 or more, physical properties such as solvent resistance and corrosion resistance of the obtained cured electrodeposition coating film are improved. On the other hand, when the number average molecular weight is 5,000 or less, the viscosity of the aminated resin can be easily adjusted to facilitate synthesis, and handling when emulsifying and dispersing the obtained aminated resin (B) is performed. Property is improved. The number average molecular weight of the aminated resin (B) is preferably in the range of 1,600 to 3,200.

  In addition, in this specification, a number average molecular weight is a number average molecular weight of polystyrene conversion measured by gel permeation chromatography (GPC).

  The amine value of the aminated resin (B) is in the range of 20 to 100 mgKOH / g. When the amine value of the aminated resin (B) is 20 mgKOH / g or more, the emulsion dispersion stability of the aminated resin (B) in the electrodeposition coating composition is improved. On the other hand, when the amine value is 100 mgKOH / g or less, the amount of amino groups in the cured electrodeposition coating film becomes appropriate, and there is no possibility of reducing the water resistance of the coating film. The amine value of the aminated resin (B) is preferably in the range of 20 to 80 mgKOH / g.

  The hydroxyl value of the aminated resin (B) is in the range of 50 to 400 mgKOH / g. When the hydroxyl value is 50 mgKOH / g or more, the cured electrodeposition coating film is cured well. On the other hand, when the hydroxyl value is 400 mgKOH / g or less, the amount of the hydroxyl group remaining in the cured electrodeposition coating film becomes appropriate, and there is no possibility of reducing the water resistance of the coating film. The hydroxyl value of the aminated resin (B) is preferably in the range of 100 to 300 mgKOH / g.

  In the electrodeposition coating composition of the present invention, an aminated resin having a number average molecular weight of 1,000 to 5,000, an amine value of 20 to 100 mgKOH / g, and a hydroxyl value of 50 to 400 mgKOH / g By using (B), there is an advantage that excellent corrosion resistance can be imparted to the article to be coated.

  In addition, as an amination resin (B), you may use together the amination resin from which an amine value and / or a hydroxyl value differ as needed. When two or more types of amine resins having different amine values and hydroxyl values are used in combination, the average amine value and average hydroxyl value calculated based on the mass ratio of the aminated resin to be used must be within the above numerical range. is there. The aminated resin (B) used in combination has an amine value of 20 to 50 mgKOH / g and a hydroxyl value of 50 to 300 mgKOH / g, and an amine value of 50 to 200 mgKOH / g. And combined use with an aminated resin having a hydroxyl value of 200 to 500 mgKOH / g is preferred. When such a combination is used, since the core part of the emulsion becomes more hydrophobic and the shell part becomes hydrophilic, there is an advantage that excellent corrosion resistance can be imparted.

  The aminated resin (B) may contain an amino group-containing acrylic resin, an amino group-containing polyester resin, or the like as necessary.

Curing agent (C)
The electrodeposition coating composition of the present invention uses a blocked isocyanate curing agent as the curing agent (C) in view of storage stability and coating performance. This curing agent (C) is also a coating film forming resin constituting the electrodeposition coating film. As the curing agent, at least one curing agent selected from the group consisting of organic curing agents such as melamine resins and phenol resins, silane coupling agents, and metal curing agents may be used in combination with the curing agent (C). The blocked isocyanate curing agent can be prepared by blocking polyisocyanate with a sealing agent.

  Examples of polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate (including trimers), tetramethylene diisocyanate, and trimethylhexamethylene diisocyanate, isophorone diisocyanate, and fats such as 4,4′-methylenebis (cyclohexyl isocyanate). Aromatic diisocyanates such as cyclic polyisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate and the like can be mentioned.

  Examples of sealants include monovalent alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol carbinol, methylphenyl carbinol; ethylene glycol mono Cellosolves such as hexyl ether and ethylene glycol mono 2-ethylhexyl ether; Polyether type terminal diols such as polyethylene glycol, polypropylene glycol and polytetramethylene ether glycol phenol; ethylene glycol, propylene glycol, 1,4-butanediol, etc. Polyester type terminal polyols obtained from diols of the above and dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, suberic acid and sebacic acid; para-t-butyl Phenols such as enol and cresol; oximes such as dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime and cyclohexanone oxime; and lactams represented by ε-caprolactam and γ-butyrolactam are preferably used. .

  The blocking ratio of the blocked isocyanate curing agent is preferably 100%. Thereby, there exists an advantage that the storage stability of an electrodeposition coating composition becomes favorable.

  In the electrodeposition coating composition of the present invention, when the curing agent (C) is a blocked isocyanate curing agent, the aminated resin (B) and the blocked isocyanate curing agent are heated and cured in the electrodeposition coating film. The condition is that the theoretical residual hydroxyl value in the case of reaction is 50 to 350 mgKOH / g. Here, the “theoretical residual hydroxyl value” means that when the electrodeposition coating obtained by electrodeposition coating is cured by heating, the aminated resin (B) reacts with the blocked isocyanate curing agent in the coating. The hydroxyl value derived from the remaining aminated resin (B) is meant.

  When the theoretical residual hydroxyl value satisfies 50 to 350 mgKOH / g, excellent corrosion resistance is exhibited in the cured electrodeposition coating film. In the cured electrodeposition coating film after the amination resin (B) and the blocked isocyanate curing agent have reacted by heat curing, the remaining hydroxyl group derived from the amination resin (B) and the dissolved metal compound (A ) Form a hydrogen bond, and this is presumed to be due to the improvement in coating film adhesion.

  The curing agent (C) which is a blocked isocyanate curing agent preferentially reacts with the primary amine of the aminated resin (B), and further reacts with a hydroxyl group to be cured. And in the electrodeposition coating film after the amination resin (B) and the blocked isocyanate curing agent reacted by heat curing, the remaining hydroxyl group derived from the amination resin (B) is dissolved with the dissolved metal compound (A). By interacting, it is thought that coating-film adhesiveness improves.

  The theoretical residual hydroxyl value in the case where the aminated resin (B) and the blocked isocyanate curing agent react during heat curing in the electrodeposition coating film is 1 with the hydroxyl value (mgKOH / g) of the aminated resin (B). The ratio of the mass of the aminated resin (B) to the sum of the mass of the aminated resin (B) and the mass of the curing agent (C) to the total of the secondary amine value (mgKOH / g) ((B) / (B) + (C)), the curing agent (C) with respect to the sum of the isocyanate group value (mgKOH / g) of the curing agent (C) and the mass of the aminated resin (B) and the mass of the curing agent (C). ) Mass ratio ((C) / (B) + (C)). For example, the primary amine value of the aminated resin is 17 mgKOH / g, the hydroxyl value is 240 mgKOH / g, the isocyanate group value of the curing agent is 252 mgKOH / g, and the mass of the aminated resin (B) is 4 with respect to the mass of the curing agent (C). If it is twice, the residual hydroxyl value is (17 + 240) × 0.8− (252 × 0.2) and is calculated as 155 mgKOH / g.

Nitrite metal salt (D)
The electrodeposition coating composition of the present invention preferably contains a metal nitrite (D) as the component (D). The nitrite metal salt (D) is different from the above-described dissolved metal compound (A), and is different from other additives described later. The nitrite metal salt is preferably a divalent metal salt of nitrous acid, and particularly preferably a calcium salt or zinc salt as the nitrite metal salt (D) from the viewpoint of paintability. In the present invention, by using the metal nitrite (D), the precipitation of the inorganic layer with the metal derived from the dissolved metal compound (A) on the object to be coated is promoted, so the adhesion is improved and the corrosion resistance is improved. There is an advantage of being excellent.
The electrodeposition coating composition of the present invention contains a metal nitrite (D). Since the nitrite metal salt (D) has a very strong oxidizing power, a smaller amount has an effect of promoting the precipitation of the inorganic layer. For this reason, since the cathode adhesion is particularly excellent, the corrosion resistance is improved.

In the present invention, by adding the metal nitrite (D), the deposition of the inorganic layer derived from the dissolved metal compound (A) is greatly promoted, and the amount of deposition of the inorganic layer on the surface of the coating is increased. The rust prevention property is improved. Further, since the action of hydrogen bonding between the inorganic layer and the resin is improved at the edge portion, the edge portion can be covered with an electrodeposition coating film having a sufficient film thickness, and the effect of inhibiting corrosion at the edge portion is greatly exhibited.

  The content of the metal nitrite (D) is preferably 0.001 to 0.2% by mass with respect to the total mass of the electrodeposition coating composition. More preferably, it is 0.01-0.06 mass%. Since the content of the metal nitrite (D) is 0.001% by mass or more, the deposition of the inorganic layer on the base material is promoted, so that the adhesion is improved and better corrosion resistance is obtained. There is. On the other hand, when it is 1% by mass or less, it is possible to achieve compatibility with the appearance of coating.

Plasticizer As described above, when the dissolved metal compound (A) is contained, the metal is deposited on the interface of the base material, and the metal derived from the dissolved metal compound (A) is taken into the resin film. Even if a metal is taken into the electrodeposition coating, the corrosion resistance of the electrodeposition coating is not reduced, but the amine resin (B), which is a coating-forming resin, in the resin coating and the metal are bonded by hydrogen bonding. Stress tends to be high and the physical properties of the coating film are likely to be hard. Therefore, in order to maintain necessary physical properties, it is desirable to improve the plasticity of the electrodeposition coating film by using a plasticizer in combination. As the plasticizer, the aminated resin may be plastically modified, the plastically modified aminated resin may be added as a secondary resin, or a plasticizer may be added.

The plasticizer is preferably an alkylene oxide adduct. Furthermore, an ethylene oxide adduct and a propylene oxide adduct are preferable. The addition method is not particularly limited, and for example, an ethylene oxide adduct, dimethylene triamine propylene oxide adduct, a reaction product of a diethylenetriamine propylene oxide adduct and an epoxy resin to bisphenol A or alcohol may be used.

  As content of a plasticizer, 0.1-25 mass% is preferable with respect to the total resin solid content of the film formation resin in an electrodeposition coating composition, More preferably, it is 1-10 mass%.

Chelating acid (E)
The electrodeposition coating composition of the present invention preferably contains a chelating acid (E). Examples of the chelating acid (E) include at least one selected from the group consisting of sulfonic acid, organic phosphonic acid, organic carboxylic acid, amino acid, aminocarboxylic acid, sugar acid, and carboxyl group-containing vinyl resin. By including the chelating acid (E) in the electrodeposition coating composition of the present invention, the metal ions derived from the dissolved metal compound (A) are chelated, the electrical conductivity is reduced, and the electrodeposition coating obtained by electrodeposition coating. There is an advantage that the appearance of the film is improved and a cured electrodeposition coating film having excellent corrosion resistance can be formed.

  Examples of the sulfonic acid as the chelating acid (E) include alkanesulfonic acid having 1 to 20 carbon atoms, phenolsulfonic acid, and aminosulfonic acid. The C1-C20 alkyl group which forms these sulfonic acids may have substituents, such as a hydroxyl group. Examples of preferable sulfonic acid include methanesulfonic acid, sulfamic acid, phenolsulfonic acid, p-toluenesulfonic acid, aminosulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and the like.

  Examples of the organic phosphonic acid as the chelating acid (E) include alkyl phosphonic acids having 1 to 20 carbon atoms, alkyl bisphosphonic acids having 1 to 20 carbon atoms, aromatic phosphonic acids having 6 to 20 carbon atoms, and 6 to 20 carbon atoms. And aromatic bisphosphonic acid. The C1-C20 alkyl group and C6-C20 aromatic group which form these phosphonic acids may have substituents, such as a hydroxyl group. Examples of preferable organic phosphonic acid include 1-hydroxyethylidene bisphosphonic acid.

  Examples of the organic carboxylic acid as the chelating acid (E) include fatty acids having 3 to 20 carbon atoms, aromatic carboxylic acids having 6 to 20 carbon atoms, oxocarboxylic acids having 2 to 20 carbon atoms, and dicarboxylic acids having 3 to 20 carbon atoms. Examples include acids and other organic carboxylic acids. The “organic carboxylic acid” here does not include an aminocarboxylic acid described later.

Examples of the fatty acid having 3 to 20 carbon atoms include propionic acid, butyric acid (butyric acid), dimethylpropionic acid (DMPA), isobutyric acid, valeric acid, isovaleric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, caprin Examples include acids, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, oleic acid and the like.
Examples of the aromatic carboxylic acid having 6 to 20 carbon atoms include salicylic acid, gallic acid, benzoic acid, phthalic acid, and cinnamic acid.

  Examples of oxocarboxylic acids having 2 to 20 carbon atoms, dicarboxylic acids having 3 to 20 carbon atoms and other organic carboxylic acids include pyruvic acid, oxalic acid, lactic acid, tartaric acid, maleic acid, fumaric acid, malonic acid, succinic acid, Examples include malic acid, citric acid, aconitic acid, glutaric acid, and adipic acid. Of these, dimethylpropionic acid and lactic acid are preferred.

  Examples of amino acids as the chelating acid (E) include aspartic acid, glutamic acid, glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, asparagine, glutamine, proline, phenylalanine, tyrosine, and tryptophan. Among these, aspartic acid and glycine are preferable.

  The aminocarboxylic acid as the chelating acid (E) is an acid having an amino group and a carboxyl group in the molecule and is a compound other than the above amino acids. Examples of aminocarboxylic acids include hydroxyethylethylenediamine triacetic acid (HEDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DPTA), triethylenetetraaminehexaacetic acid, and the like.

  The sugar acid as the chelating acid (E) is a sugar derivative having a carboxyl group obtained by oxidizing a monosaccharide. Examples of sugar acids include aldonic acid (such as gluconic acid, galactonic acid, and mannonic acid), uronic acid (such as glucuronic acid, galacturonic acid, and mannuronic acid), aldaric acid (such as glucaric acid, galactaric acid, and mannal acid), and iduronic acid. Glyceric acid, sialic acid, threonic acid, pangamic acid, ascorbic acid, muramic acid, lactobionic acid and the like.

  Examples of the carboxyl group-containing vinyl resin as the chelating acid (E) include a carboxyl group-containing polyvinyl alcohol resin. The carboxyl group-containing polyvinyl alcohol resin is produced, for example, by a method of copolymerizing a monomer such as acrylic acid together with a vinyl acetate monomer in the procedure for preparing polyvinyl alcohol, and then hydrolyzing the obtained polyvinyl acetate. be able to.

  Among these chelating acids (E), it is more preferable to use alkanesulfonic acid, organic phosphonic acid, organic carboxylic acid and / or amino acid, and methanesulfonic acid, dimethylpropionic acid or lactic acid to use chelating function and coating. This is particularly preferable from the viewpoint of less adverse effects due to adsorption to the membrane.

  In the present invention, the chelating acid (E) is preferably contained in the electrodeposition coating composition in an amount of 0.1 to 10 equivalents relative to the dissolved metal compound (A).

  When alkanesulfonic acid and / or organic phosphonic acid is included as chelating acid (E), the total number of equivalents of sulfone groups or phosphonic groups possessed by alkanesulfonic acid and / or organic phosphonic acid, and dissolved metal compound (A ) In an amount of 0.1: 1 to 10: 1 with respect to the number of moles of metal is preferably contained in the electrodeposition coating composition.

  When chelating acid (E) includes organic carboxylic acid, amino acid, aminocarboxylic acid, sugar acid and / or carboxyl group-containing vinyl resin, the total number of equivalents of carboxyl groups of these components and dissolved metal compound (A) It is preferable to contain in an electrodeposition coating material composition in the quantity used as the ratio with the number-of-moles of a metal of 0.1: 1-10: 1.

  By using the chelating acid (E) in an amount of 0.1 to 10 equivalents relative to the dissolved metal compound (A), the amount of metal ions derived from the dissolved metal compound (A) and the chelating acid (E) Thus, the precipitation of the inorganic layer containing the metal derived from the dissolved metal compound (A) can be improved, and the corrosion resistance is not impaired by the chelating acid (E), which is more excellent. There is an advantage that a cured electrodeposition coating film having corrosion resistance can be formed.

Aminosilane compound (F)
The electrodeposition coating composition of the present invention preferably contains an aminosilane compound (F). Examples of the aminosilane compound (F) include an aminosilane having at least one amino group in one molecule, and a hydrolysis condensate of aminosilane.

  Specific examples of aminosilane having at least one amino group in one molecule include N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and 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-aminopropyltrimethoxysilane, and N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride. “KBM-602”, “KBM-603”, “KBE-603”, “KBM-903”, “KBE-903”, “KBE-9103”, “KBM-603”, which are commercially available amino group-containing silane coupling agents "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.

  As the aminosilane compound (F), a hydrolysis condensate of aminosilane can also be used. By using a hydrolyzed condensate of aminosilane, there is an advantage that the adhesion of the electrodeposition coating film to the object can be improved. The molecular weight of the hydrolyzed condensate of aminosilane is not particularly limited, but a high molecular weight is preferable from the viewpoint of improving corrosion resistance. Here, the high molecular weight corresponds to that in which Si is three-dimensionally condensed by condensation. When the aminosilane is subjected to a hydrolytic condensation reaction, it is preferable that the aminosilane is reacted under a condition that the aminosilane is more easily hydrolyzed and condensed. The conditions under which aminosilane is more easily hydrolyzed and condensable include, for example, reaction conditions in which a solvent is an alcohol, and reaction conditions by blending aminosilane that results in cocondensation rather than single condensation as described above. In addition, by carrying out the reaction under a condition where the aminosilane concentration is relatively high, a hydrolyzed condensate can be obtained under a condition of higher molecular weight and higher condensation rate. Specifically, it is preferable to condense the aminosilane concentration in the range of 5 mass% or more and 50 mass% or less. The aminosilane may be co-condensed with an alkoxysilane having no amino group such as epoxy silane “KBM-403” (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) as necessary.

  By including the aminosilane compound (F) in the electrodeposition coating composition, there is an advantage that adhesion is improved and corrosion resistance is excellent by the action of the amino group of the aminosilane compound (F).

  In the electrodeposition coating composition of the present invention, when the aminosilane compound (F) is used, the mass of the aminosilane compound (F) with respect to the total mass of the electrodeposition coating composition is within the range of 0.001 to 0.5% by mass. Preferably there is. The effect by using an aminosilane compound (F) is acquired because content of an aminosilane compound (F) is 0.001 mass% or more. Moreover, when the content of the aminosilane compound (F) is 0.5% by mass or less, an effect of improving the corrosion resistance according to the content is obtained, which is economically advantageous. When the aminosilane compound (F) is used as a cation dispersant for the dissolved metal compound (A) or a pH adjuster, the total amount including them is preferably within the above range.

Other ingredients
Pigment The electrodeposition coating composition of the present invention may contain a pigment usually used in electrodeposition coating compositions. Examples of pigments include commonly used inorganic pigments, for example, colored pigments such as titanium white, carbon black and bengara; extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica and clay; phosphoric acid And iron, aluminum phosphate, calcium phosphate, aluminum tripolyphosphate, and rust preventive pigments such as aluminum phosphomolybdate and zinc aluminum phosphomolybdate. When these pigments are contained in the electrodeposition coating composition, the amount of the pigment is preferably 1 to 30% by mass with respect to the resin solid content of the electrodeposition coating composition.

  When a pigment is used as a component of an electrodeposition paint, generally the pigment is previously dispersed in an aqueous solvent at a high concentration to form a paste (pigment dispersion paste). This is because the pigment is in a powder form, and it is difficult to disperse in a single step in a low concentration uniform state used in the electrodeposition coating composition. Such a paste is generally called a pigment dispersion paste.

  The pigment dispersion paste is prepared by dispersing a pigment together with a pigment dispersion resin in an aqueous solvent. As the pigment dispersion resin, a pigment dispersion resin having a cationic group such as a modified epoxy resin having at least one selected from a quaternary ammonium group, a tertiary sulfonium group, and a primary amine group can be used. As the aqueous solvent, ion-exchanged water or water containing a small amount of alcohol is used. Generally, the pigment dispersion resin is used in an amount of 20 to 100 parts by mass of the resin solid content ratio with respect to 100 parts by mass of the pigment. After the pigment dispersion resin and the pigment are mixed, the pigment is dispersed using a normal dispersing device such as a ball mill or a sand grind mill until the pigment particle size in the mixture reaches a predetermined uniform particle size. A paste can be obtained.

Other Additives The electrodeposition coating composition of the present invention is an organic coating such as ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monoethyl hexyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, and propylene glycol monophenyl ether. Surfactants such as solvents, anti-drying agents, antifoaming agents, viscosity modifiers such as acrylic resin fine particles, anti-foaming agents, inorganic rust inhibitors such as vanadium salts, copper, iron, manganese, magnesium, calcium salts, etc. Conventional paint additives may be added as necessary. In addition to these, known auxiliary complexing agents, buffering agents, smoothing agents, stress relaxation agents, brighteners, semi-brightening agents, antioxidants, ultraviolet absorbers and the like may be blended depending on the purpose.

Other coating film-forming resin components The electrodeposition coating composition of the present invention is not limited to the above-mentioned aminated resin (B), but may be an aminated resin not corresponding to the above-mentioned aminated resin (B), and / or other A film-forming resin component may be included. Examples of other film forming resin components include acrylic resin, polyester resin, urethane resin, butadiene resin, phenol resin, xylene resin, and the like. Phenol resins and xylene resins are preferred as other film-forming resin components that can be included in the electrodeposition coating composition. Examples of the phenol resin and xylene resin include xylene resins having 2 or more and 10 or less aromatic rings.

  In the present specification, the “resin solid content” means the solid mass of all solid contents of the coating film-forming resin contained in the electrodeposition coating composition. Specifically, it means the total amount of the solid content mass of the aminated resin (B), the curing agent (C), and other coating film-forming resin components as required, contained in the electrodeposition coating composition.

  The resin solid content of the electrodeposition coating composition is preferably 1 to 30% by mass with respect to the electrodeposition coating composition. When the resin solid content of the electrodeposition coating composition is less than 1% by mass, the amount of electrodeposition coating film deposited decreases, and it may be difficult to ensure sufficient corrosion resistance. Moreover, when the resin solid content of an electrodeposition coating composition exceeds 30 mass%, there exists a possibility that throwing power and coating appearance may worsen.

Preparation of electrodeposition coating composition The electrodeposition coating composition of the present invention comprises an emulsion containing an aminated resin (B) and a curing agent (C), a pigment dispersion paste as required, and a dissolved metal compound (A). And a nitrite metal salt (D), a chelate acid (E), an aminosilane compound (F), a plasticizer, and the like, and can be prepared by mixing.

  In preparing the electrodeposition coating composition, the aminated resin (B) is neutralized with a neutralizing acid to improve dispersibility and form an emulsion. Organic acids such as formic acid, acetic acid and lactic acid are used as the neutralizing acid used for neutralization of the aminated resin (B). In the present invention, it is more preferable to neutralize and disperse the aminated resin (B) using formic acid. When formic acid is used as a neutralizing acid for neutralizing and dispersing the aminated resin (B), there is an advantage that the throwing power is excellent because the degree of dissociation is high.

  The amount of the neutralizing acid used is in the range of 10 to 25 mg equivalent to 100 g of resin solid content including the aminated resin (B), the curing agent (C) and the coating film forming resin as required. Is preferred. The lower limit is more preferably 15 mg equivalent, and the upper limit is more preferably 20 mg equivalent. When the amount of the neutralizing acid is 10 mg equivalent or more, the affinity for water is sufficient and the dispersion in water is good. On the other hand, when the amount of the neutralizing acid is 25 mg equivalent or less, the amount of electricity required for the precipitation becomes appropriate, and the depositability and throwing power of the paint solids become good.

  The amount of the curing agent (C) reacts with active hydrogen-containing functional groups such as primary amino group, secondary amino group, and hydroxyl group in the aminated resin (B) at the time of curing to give a good cured coating film. A sufficient amount is required. A preferable amount of the curing agent (C) is 90/10 to 50 in terms of a solid content mass ratio of the aminated resin (B) and the curing agent (C) (aminated resin (B) / curing agent (C)). / 50, more preferably in the range of 80/20 to 65/35. By adjusting the solid content mass ratio of the aminated resin (B) and the curing agent (C), the fluidity and curing speed of the coating film (deposition film) during film formation are improved, and the coating appearance is improved.

  The electrodeposition coating composition comprises a resin emulsion in which an aminated resin (B), a curing agent (C) and other coating-forming resin components as necessary are dispersed using a neutralizing acid, a pigment dispersion paste, and It can be prepared by adding and mixing the dissolved metal compound (A), metal nitrite (D), chelate acid (E), aminosilane compound (F), plasticizer and the like. The dissolved metal compound (A) may be added together with the pigment as a dispersion paste.

  The electrodeposition coating composition of the present invention preferably has a pH of 2-6. Moreover, it is preferable that the milligram equivalent (MEQ (A)) of the acid with respect to 100 g of resin solid content of an electrodeposition coating composition is 40-120. In addition, the milligram equivalent (MEQ (A)) of the acid with respect to 100 g of the resin solid content of the electrodeposition coating composition can be adjusted by the amount of neutralized acid and the amount of free acid.

  Here, MEQ (A) is an abbreviation for mg equivalent (acid), and is the sum of mg equivalents of all acids per 100 g of solid content of the paint. This MEQ (A) is prepared by accurately weighing about 10 g of the electrodeposition coating composition and dissolving it in about 50 ml of a solvent (THF: tetrahydrofuran), and then performing potentiometric titration using a 1/10 N NaOH solution. The amount of acid contained in the coating composition can be quantified and measured. The pH of the electrodeposition coating composition can be measured using a commercially available pH meter having a temperature correction function.

  The electrodeposition coating composition of the present invention preferably contains substantially no tin compound or lead compound. In the present specification, “the electrodeposition coating composition is substantially free of both a tin compound and a lead compound” means that the concentration of the lead compound contained in the electrodeposition coating composition does not exceed 50 ppm as a lead metal element, And it means that the concentration of the organic tin compound does not exceed 50 ppm as a tin metal element. In the electrodeposition coating composition of the present invention, the dissolved metal compound (A) containing one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr Is included. Therefore, it is not necessary to use a lead compound or an organic tin compound as a curing catalyst. Thereby, the electrodeposition coating composition which does not contain any of a tin compound and a lead compound can be prepared.

Electrodeposition coating and electrodeposition coating formation
Coatings Various coatings that can be energized can be used as coatings for applying the electrodeposition coating composition of the present invention. Examples of coatings that can be used include cold-rolled steel sheets, hot-rolled steel sheets, stainless steel, electrogalvanized steel sheets, hot-dip galvanized steel sheets, zinc-aluminum alloy plated steel sheets, zinc-iron alloy plated steel sheets, zinc-magnesium alloy based plating. Examples of the coating material include steel plates, zinc-aluminum-magnesium alloy-plated steel plates, aluminum-plated steel plates, aluminum-silicon alloy-plated steel plates, and tin-based plated steel plates.

  The electrodeposition coating composition of the present invention can be suitably used in coating using an object to be coated having a chemical conversion film formed from a zirconium chemical conversion treatment composition. In an electrodeposition coating using a general electrodeposition coating composition, a zinc phosphate chemical conversion treatment is performed on an object to be coated before electrodeposition coating. By applying this chemical conversion treatment to the article to be coated, the corrosion resistance of the formed coating film is improved, and the adhesion between the article to be coated and the coating film is further improved. While the chemical conversion treatment before electrodeposition coating has such advantages, there is a problem of sludge generation when using a zinc phosphate chemical conversion treatment agent. In addition, when the chemical conversion treatment is performed using the zinc phosphate chemical conversion treatment agent, cleaning after the chemical conversion treatment is indispensable, so that the coating process becomes complicated, and the cost of installing the equipment and the maintenance cost are generated.

  On the other hand, the electrodeposition coating composition of the present invention is a coating film excellent in corrosion resistance even when a coating film is formed using a coating having a chemical conversion film formed by the zirconium chemical conversion treatment composition. It has the characteristic that can be formed. By using the electrodeposition coating composition of the present invention, it is possible to reduce the cost and labor required for sludge treatment and the like accompanying zinc phosphate chemical conversion treatment.

  As the zirconium chemical conversion treatment composition, a zirconium chemical conversion treatment composition usually used by those skilled in the art can be used. As a specific example of the zirconium chemical conversion treatment composition, for example, at least one selected from the group consisting of zirconium, titanium and hafnium, fluorine, and a zirconium chemical conversion treatment composition containing an adhesion and corrosion resistance imparting agent such as a water-soluble polyamine resin Such as things.

  In addition, you may remove foreign materials, such as a rust preventive oil and a processing oil which adhered to the to-be-coated object, using an alkaline degreasing liquid and / or washing water before a zirconium chemical conversion treatment as needed.

Electrodeposition process Electrodeposition is usually carried out by applying a voltage of 50 to 450 V between the object to be coated as the cathode and the anode. If the applied voltage is less than 50V, electrodeposition may be insufficient, and if it exceeds 450V, the coating film may be destroyed and an abnormal appearance may be obtained. At the time of electrodeposition coating, the bath temperature of the coating composition is usually adjusted to 10 to 45 ° C.

  The electrodeposition coating process includes a process of immersing an object to be coated in an electrodeposition coating composition, and a process of applying a voltage between the object to be coated as a cathode and an anode to deposit a film. Moreover, although the time which applies a voltage changes with electrodeposition conditions, generally it can be made into 2 to 5 minutes.

  The film thickness of the electrodeposition coating film after baking is preferably 5 to 40 μm, more preferably 10 to 25 μm. If the film thickness is less than 5 μm, the corrosion resistance may be insufficient. On the other hand, if it exceeds 40 μm, it leads to waste of paint.

  The electrodeposition coating film obtained as described above is baked by baking it at 120 to 260 ° C., preferably 140 to 220 ° C. for 10 to 30 minutes after completion of the electrodeposition process or after washing with water. A cured cured electrodeposition coating is formed.

  The electrodeposition coating composition of the present invention has an advantage that excellent corrosion resistance can be obtained even when electrodeposition coating is performed using an object to be coated having a chemical conversion coating formed by a zirconium chemical conversion treatment composition. The electrodeposition coating composition of the present invention contains a specific dissolved metal compound (A) and has a theoretical residual hydroxyl value of 50 to 350 mgKOH / g when reacting at the time of heat curing in the electrodeposition coating film. It has that characteristic. And by this feature, in the cured electrodeposition coating film after the aminated resin (B) and the blocked isocyanate curing agent have reacted by heat curing, the remaining hydroxyl group derived from the aminated resin (B) and the dissolved metal compound (A) forms a hydrogen bond, thereby providing excellent adhesion in a cured electrodeposition coating film, resulting in excellent corrosion resistance and a coating with a high coating smoothness. There is an advantage that a film is obtained.

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Production Example 1-A Production of Aminated Resin (Resin A) 92 parts of methyl isobutyl ketone, 940 parts of bisphenol A type epoxy resin (trade name DER-331J, manufactured by Dow Chemical Company), 350 parts of bisphenol A, 30 parts of octylic acid, dimethyl 2 parts of benzylamine was added, the temperature in the reaction vessel was kept at 120 ° C., and the reaction was continued until the epoxy equivalent reached 820 g / eq, followed by cooling until the temperature in the reaction vessel reached 110 ° C. Next, 160 parts of diethanolamine was added and reacted at 110 ° C. for 1 hour to obtain an aminated resin (cation-modified epoxy resin: resin A).

  The number average molecular weight of this resin was 2,600, the amine value was 58 mgKOH / g, and the hydroxyl value was 310 mgKOH / g.

Production Example 1-B Production of Aminated Resin (Resin B) 92 parts of methyl isobutyl ketone, 940 parts of bisphenol A type epoxy resin (trade name DER-331J, manufactured by Dow Chemical Company), 350 parts of bisphenol A, 95 parts of octylic acid, dimethyl 2 parts of benzylamine was added, the temperature in the reaction vessel was maintained at 120 ° C., and the reaction was continued until the epoxy equivalent reached 1170 g / eq, followed by cooling until the temperature in the reaction vessel reached 110 ° C. Then, a mixture of 82 parts of diethylenetriamine diketimine (a methyl isobutyl ketone solution having a solid content of 73%), 26 parts of N-methylethanolamine and 60 parts of diethanolamine was added and reacted at 110 ° C. for 1 hour to give an aminated resin (cationic). Modified epoxy resin: Resin B) was obtained.

  The number average molecular weight of this resin was 2,600, the amine value was 58 mgKOH / g (of which the amine value derived from the primary amine was 17 mgKOH / g), and the hydroxyl value was 240 mgKOH / g.

Production Example 1-C Production of Aminated Resin (Resin C) 92 parts of methyl isobutyl ketone, 940 parts of bisphenol A type epoxy resin (trade name DER-331J, manufactured by Dow Chemical Company), 350 parts of bisphenol A, 25 parts of octylic acid, dimethyl 2 parts of benzylamine was added, the temperature in the reaction vessel was maintained at 120 ° C., and the reaction was continued until the epoxy equivalent reached 800 g / eq, and then the reaction vessel was cooled to 110 ° C. Then, a mixture of 160 parts of diethanolamine and 190 parts of an adduct of 37 mol of diethylenetriaminepropion oxide was added and reacted at 110 ° C. for 1 hour to obtain an aminated resin (cation-modified epoxy resin: resin C).

  The number average molecular weight of this resin was 3,300, the amine value was 58 mgKOH / g (of which the amine value derived from the primary amine was 5 mgKOH / g), and the hydroxyl value was 270 mgKOH / g.

Production Example 1-E Production of Aminated Resin (Resin E) 92 parts of methyl isobutyl ketone, 940 parts of bisphenol A type epoxy resin (trade name DER-331J, manufactured by Dow Chemical Company), 390 parts of bisphenol A, 80 parts of octylic acid, dimethyl 2 parts of benzylamine was added, the temperature in the reaction vessel was kept at 120 ° C., and the reaction was continued until the epoxy equivalent reached 1400 g / eq, followed by cooling until the temperature in the reaction vessel reached 110 ° C. Subsequently, a mixture of 100 parts of diethanolamine and 120 parts of a 37 mol adduct of diethylenetriaminepropion oxide was added and reacted at 110 ° C. for 1 hour to obtain an aminated resin (cation-modified epoxy resin: resin E).

  The number average molecular weight of this resin was 3,300, the amine value was 37 mgKOH / g (of which the amine value derived from primary amine was 3 mgKOH / g), and the hydroxyl value was 240 mgKOH / g.

Production Example 1-F Production of aminated resin (resin F) A reaction vessel equipped with a stirrer, decanter, nitrogen introduction tube, thermometer and dropping funnel was charged with a bisphenol A type epoxy resin (trade name DER) having an epoxy equivalent of 188 g / eq. -331J, manufactured by Dow Chemical Co., Ltd.), 2,400 parts, 141 parts of methanol, and 168 parts of methyl isobutyl ketone were stirred and dissolved uniformly at 40 ° C., and then 2,4- / 2,6-tolylene diisocyanate ( When 80 parts of 80/20 mass ratio mixture) was added dropwise over 30 minutes, heat was generated and the temperature rose to 70 ° C. To this was added 5 parts of N, N-dimethylbenzylamine, the temperature in the reaction vessel was raised to 120 ° C., and the reaction was continued at 120 ° C. for 3 hours until the epoxy equivalent reached 500 g / eq while distilling off methanol. It was. Further, 644 parts of methyl isobutyl ketone, 341 parts of bisphenol A and 413 parts of 2-ethylhexanoic acid were added, and the reaction container was maintained at a temperature of 120 ° C. until the epoxy equivalent reached 1070 g / eq. The inner temperature was cooled to 110 ° C. Next, a mixture of 241 parts of diethylenetriamine diketimine (a methyl isobutyl ketone solution having a solid content of 73%) and 192 parts of N-methylethanolamine was added and reacted at 110 ° C. for 1 hour, whereby an aminated resin (cation-modified epoxy resin: Resin F) was obtained.

The number average molecular weight of this resin was 2,100, the amine value was 74 mgKOH / g (of which the amine value derived from the primary amine was 16 mgKOH / g), and the hydroxyl value was 160 mgKOH / g. Moreover, it was confirmed from the measurement of an infrared absorption spectrum etc. that the resin has an oxazolidone ring (absorption wave number: 1750 cm ⁻¹ ).

Production Example 2-1 Production of Blocked Isocyanate Curing Agent (1) 1680 parts of hexamethylene diisocyanate (HDI) and 732 parts of MIBK were charged into a reaction vessel and heated to 60 ° C. A solution obtained by dissolving 346 parts of trimethylolpropane in 1067 parts of MEK oxime was added dropwise at 60 ° C. over 2 hours. Further, after heating at 75 ° C. for 4 hours, in the measurement of IR spectrum, it was confirmed that the absorption based on the isocyanate group disappeared, and after standing to cool, 27 parts of MIBK was added to add a blocked isocyanate curing agent (1 ) The isocyanate group value was 252 mgKOH / g.

Production Example 2-2 Production of Blocked Isocyanate Curing Agent (2) 1,340 parts of 4,4′-diphenylmethane diisocyanate and 277 parts of MIBK were charged into a reaction vessel and heated to 80 ° C., and then 226 parts of ε-caprolactam was added to butyl cellosolve. What was dissolved in 944 parts was dripped at 80 degreeC over 2 hours. Furthermore, after heating at 100 degreeC for 4 hours, in the measurement of IR spectrum, it confirmed that the absorption based on an isocyanate group disappeared, and after standing to cool, MIBK349 parts were added and block isocyanate hardening | curing agent (2) was obtained (solid). Min 80%). The isocyanate group value was 251 mgKOH / g.

Production Example 3 Production of Pigment Dispersion Resin 385 parts of bisphenol A type epoxy resin, 120 parts of bisphenol A, 95 parts of octylic acid, 2-ethyl-4-methyl in a reaction vessel equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe and a thermometer 1 part of imidazole 1% solution was charged, reacted at 160-170 ° C. for 1 hour under a nitrogen atmosphere, then cooled to 120 ° C., and then methyl isobutyl ketone solution of 2-ethylhexanolated half-blocked tolylene diisocyanate (solid content 95 %) 198 parts were added. After maintaining the reaction mixture at 120-130 ° C. for 1 hour, ethylene glycol mono n-butyl ether 157 was added. And it cooled to 85-95 degreeC and made it uniform. Next, 277 parts of diethylenetriamine diketimine (a methyl isobutyl ketone solution having a solid content of 73%) was added and stirred at 120 ° C. for 1 hour, and 13 parts of ethylene glycol mono-n-butyl ether was added to produce an aminated resin. Next, 18 parts of ion-exchanged water and 8 parts of formic acid were added, the aminated resin was mixed and stirred for 15 minutes, 200 parts of ion-exchanged water was mixed, and a resin solution of pigment-dispersed resin (number average molecular weight 2,200) ( Resin solid content 25%) was obtained.

Production Examples 4-A to C, 4-E, 4-F Electrodeposition Paint Resin Emulsions (EmA) to (EmC), (EmE), (EmF) Production of Resin (Resin A) Obtained in Production Example 1-A 350 g (solid content), 75 g (solid content) of the blocked isocyanate curing agent (1) obtained in Production Example 2-1 and 75 g (solid content) of the curing agent (2) were mixed, and ethylene glycol mono-2-ethylhexyl was mixed. Ether was added to 3% (15 g) based on solids. Next, neutralize by adding methanesulfonic acid to a neutralization rate of 80%, add ion-exchanged water to dilute slowly, and then remove methyl isobutyl ketone under reduced pressure to a solid content of 36%. Thus, an electrodeposition paint resin emulsion (EmA) was obtained.
Further, instead of the resin (resin A) obtained in Production Example 1-A, the resins (Resin B), (Resin C), (Resin E) obtained in Production Examples 1-B, C, E, and F, respectively, Electrodeposition paint resin emulsions (EmB), (EmC), (EmE), and (EmF) were obtained in the same manner except that (Resin F) was used.

Production Example 4-D Production of Electrodeposition Paint Resin Emulsion (EmD ) 400 g (solid content) of resin (resin A) obtained in Production Example 1-A and blocked isocyanate curing agent (1) obtained in Production Example 2-1. 50 g (solid content) and curing agent (2) 50 g (solid content) were mixed, and ethylene glycol mono-2-ethylhexyl ether was added to 3% (15 g) based on the solid content. Next, neutralize by adding methanesulfonic acid to a neutralization rate of 80%, add ion-exchanged water to dilute slowly, and then remove methyl isobutyl ketone under reduced pressure to a solid content of 36%. Thus, an electrodeposition coating resin emulsion (EmD) was obtained.

Production Example 5-1 Production of Pigment Dispersion Paste 1 for Electrodeposition Paint Using a sand mill, based on the formulation shown in the following Table 1 including the pigment dispersion resin obtained in Production Example 3, the obtained mixture was obtained at 40 ° C. Dispersion was carried out until the volume average particle diameter D50 was 0.6 μm, and pigment dispersion paste 1 (solid content 49%) was obtained. The volume average particle diameter D50 is measured by diluting the dispersion with ion-exchanged water so that the signal level is suitable using a laser Doppler particle size analyzer (manufactured by Nikkiso Co., Ltd., “Microtrac UPA150”). The particle diameter D50 was measured.

Production Example 5-2 Production of Pigment Dispersion Paste 2 for Electrodeposition Paint Based on the formulation shown in Table 2, the obtained mixture was dispersed at 40 ° C. until the volume average particle diameter D50 was 0.6 μm, and prepared. Pigment dispersion paste 2 (solid content 49%) was obtained.

Example 1
119 g of ion exchange water, 32.6 g of zinc oxide (reagent), 110 g of 70% methanesulfonic acid (manufactured by BASF) were added to a stainless steel container, and stirred at 60 ° C. for 1 hour to prepare zinc methanesulfonate having a zinc concentration of 10%. .

Next, organosilane hydrolysis-condensation product 1 includes 15 parts by mass of “KBE903” (3-aminopropyltriethoxysilane, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), “KBE603” (N-2- (amino 15 parts by weight of ethyl) -3-aminopropyltriethoxysilane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and 70 parts by weight of ion-exchanged water (solvent temperature: 25 ° C.) as a solvent over 60 minutes. Then, a hydrolyzed condensate (hereinafter referred to as KBE903-KBE603 co-condensate) of 30% active ingredient obtained by reacting at 25 ° C. for 24 hours under a nitrogen atmosphere was used.

Next, hydrolyzed condensate 2 of organosilane was “KBE903” (3-aminopropyltriethoxysilane, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), 15 parts by mass, and “KBE403” (3-glycidoxypropyl). 15 parts by mass of trimethoxysilane (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise from a dropping funnel as 60 parts by mass of ion-exchanged water (solvent temperature: 25 ° C.) as a solvent, and then 10% of 70% methanesulfonic acid was added. A hydrolytic condensate (hereinafter referred to as KBE903-KBM403 co-condensate) of 30% active ingredient obtained by adding part by mass and reacting at 25 ° C. for 24 hours under a nitrogen atmosphere was used.

To the stainless steel container, 1022 g of ion-exchanged water and 20 g of zinc methanesulfonate (expressed as “MSAZn” in Table 3) having a zinc concentration of 10% as a dissolved metal compound (A) were added. Next, 1.3 g of hydrolyzed condensate of organosilane (referred to as “organosiloxane condensate” in Table 3) is added, 1.3 g of 30% calcium nitrite (manufactured by Nissan Chemical Industries) is added, Next, 833 g of the electrodeposition paint resin emulsion (EmA) of Production Example 4-A and 122 g of the pigment (Pigment Dispersion Paste 1 of Production Example 5-1) were added, and then aged at 40 ° C. for 16 hours to obtain an electrodeposition paint composition. Formed. Table 3 below shows the blending amount of the electrodeposition coating composition, but describes the relative ratio with respect to 100 parts by mass of the solid content.

A cold-rolled steel plate (JIS G3141, SPCC-SD) was immersed in Surf Cleaner EC90 (manufactured by Nippon Paint Co., Ltd.) at 50 ° C. for 2 minutes for degreasing treatment. After deionized water washing, a necessary amount of 2-ethylhexyl glycol is added to the obtained electrodeposition coating composition so that the film thickness of the electrodeposition coating film after curing is 15 μm, and then all the cold-rolled steel sheets are buried. Immediately after that, voltage application is started, voltage is applied under the condition that the voltage is increased for 30 seconds, and reaches 180V and then held for 150 seconds, thereby forming an uncured electrodeposition film on the object to be coated (cold rolled steel sheet). Precipitated. The uncured electrodeposition film thus obtained was heat-cured at 160 ° C. for 15 minutes to obtain an electrodeposition coated plate having an electrodeposition film.

  The obtained electrodeposition coating film was evaluated for edge corrosion test, salt water immersion test (SDT), cycle corrosion test (CCT), coating film properties, coating appearance and stability. The results are shown in Table 3.

Edge corrosion test The evaluation of this test was performed by immersing an L-type spare blade (LB10K: manufactured by Olfa Co., Ltd.) for 2 minutes at 50 ° C. in Surf Cleaner EC90 (manufactured by Nippon Paint Co., Ltd.). After degreasing and washing with deionized water, the paints of Examples and Comparative Examples were electrodeposited under the same conditions as the above electrodeposition coating to form a cured electrodeposition coating film, and then subjected to a salt spray test 35 ° C. × 168 h test The number of rust at the tip of the L-type dedicated replacement blade was examined. In Example 20, a L-type exclusive blade (LB10K: manufactured by Olfa Co., Ltd.) was immersed in Surf Cleaner EC90 (manufactured by Nippon Paint Co., Ltd.) at 50 ° C. for 2 minutes for degreasing treatment, and zinc phosphate chemical conversion treatment was performed. After forming a cured electrodeposition coating film by electrodeposition-coating the paint of Example 20 on this, the number of rusts on the tip of the L-type exclusive blade after the salt spray test 35 ° C. × 168 h test was examined. .
Evaluation criteria ◎: Less than 5 ○: 5 or more and less than 10 ○ △: 10 or more and less than 20 Δ: 20 or more and less than 50 ×: 50 or more

Salt water immersion test (SDT)
The cured electrodeposition coated plate using cold-rolled steel sheet is scratched with a small cutter knife so as to reach the object to be coated, and this coated plate is immersed in 5% saline at 50 ° C. for 480 hours. Then, rust and blister generation from the linear scratches were observed and evaluated. The evaluation criteria are as follows.
Evaluation standard ◎: No rust or blisters ○: Maximum width of rust or blisters is less than 2.5 mm from the cut (both sides)
○ △: The maximum width of rust or swelling is 2.5mm or more and less than 5mm from the cut part (both sides)
Δ: The maximum width of rust or swelling is 5 mm or more and less than 10 mm from the cut part (both sides)
Δ: The maximum width of rust or swelling is 10 mm or more and less than 15 mm from the cut part (both sides)
X: The maximum width of rust or blister is 15mm or more from the cut part (both sides)

Cycle Corrosion Test (CCT)
The coating film of the electrodeposition coating plate after curing using a cold-rolled steel plate was cut with a knife so as to reach the substrate, and JASO M609-91 “Automobile Material Corrosion Test Method” was performed 60 cycles. Thereafter, the occurrence of rust and blistering from the crosscut portion was observed to evaluate the corrosion resistance in accordance with the actual corrosive environment. The evaluation criteria are as follows.
Evaluation standard ◎: Maximum width of rust or swelling is less than 5mm from the cut part (both sides)
○: The maximum width of rust or swelling is 5 mm or more and less than 7.5 mm from the cut part (both sides)
○ △: Maximum width of rust or swelling is 7.5 mm or more and less than 10 mm from the cut part (Both sides) △: Maximum width of rust or swelling is 10 mm or more and less than 12.5 mm (Both sides) from the cut part
Δ: The maximum width of rust or swelling is 12.5 mm or more and less than 15 mm from the cut part (both sides)
X: The maximum width of rust or blister is 15mm or more from the cut part (both sides)

Cured electrodeposition coating properties evaluation (film properties)
A small cutter knife is vertically applied to the electrodeposition coating plate having a cured electrodeposition coating film obtained from the above examples and comparative examples, and 11 parallel lines that reach the object to be coated are drawn at intervals of 2 mm, Eleven equidistant parallel lines perpendicular to these parallel lines were drawn at 2 mm intervals, and 100 squares of 2 mm square surrounded by four straight lines were engraved. Next, the test piece was immersed in ion exchange water at 50 ° C. for 480 hours. After immersion, wipe off the water of the test piece, and then press the adhesive tape (ELPACK LP-24 manufactured by Nichiban Co., Ltd.) (width 24 mm) without any bubbles in the cut part of the test coating film, and then pull it rapidly. It was. Based on the presence or absence of peeled grids, the following criteria were used for evaluation.
Evaluation criteria ○: No peeling ×: With peeling

Cured electrodeposition coating appearance (paint appearance)
About the electrodeposition coating plate which has the cured electrodeposition coating film obtained from the said Example and comparative example, the presence or absence of abnormality in a coating-film external appearance was judged visually. The evaluation criteria were as follows.
Evaluation Criteria A: Very uniform coating appearance B: Uniform coating appearance B: Appears if there is some unevenness, but almost uniform coating as a whole Appearance △: Unevenness is visually recognized x: Appearance of the coating is clearly uneven

Stability of electrodeposition coating composition (stability)
In a state where the electrodeposition coating composition was left standing or stirred, the state of the coating composition was visually determined to evaluate the stability. The evaluation criteria were as follows. The term “stable” as used herein means that the pigment does not settle within 15 minutes after the stirring is stopped.
Evaluation criteria ○: Stable when the electrodeposition coating composition is left standing ○ △: Although it is not stable when the electrodeposition coating composition is left still, it is stabilized immediately by stirring again Δ: Electric It is stable when the coating composition is continuously stirred. X: It is not stabilized even when the electrodeposition coating composition is continuously stirred.

Examples 2 to 23 and Comparative Examples 1 to 5
An electrodeposition coating composition was formed with the formulation shown in Table 3. For the obtained electrodeposition coating composition or electrodeposition coated plate, the same five items as in Example 1 were evaluated. The results are shown in Table 3.

  In Table 3, reagents were used for fluorinated titanic acid, yttrium nitrate, zirconic fluoride, aspartic acid, and nickel acetate.

  MSA bismuth of Example 5 was prepared by adding 202 g of ion-exchanged water, 2.6 g of bismuth hydroxide (reagent), and 4.1 g of 70% methanesulfonic acid (manufactured by BASF) to a stainless steel container and stirring at 60 ° C. for 1 hour. did. The bismuth concentration was 1% by mass.

  In Examples 15 to 16 and 23, the pigment dispersion paste 2 prepared in Production Example 5-2 was used.

  In Example 2, a mixture of Pigment Dispersion Paste 1 prepared in Production Example 5-1: Pigment Dispersion Paste 2 prepared in Production Example 5-2 = 5: 5 (mass ratio) was used. In Example 14, a mixture of Pigment Dispersion Paste 1 prepared in Production Example 5-1: Pigment Dispersion Paste 2 produced in Production Example 5-2 = 9: 1 (mass ratio) was used.

  The BPAEO adduct used in Example 19 was a plasticizer and was an ethylene oxide adduct (BPAEO adduct) of bisphenol A (manufactured by New Pole BPE-60 Sanyo Chemical Industries).

The value of the dissolved metal compound (A) in Table 3 is a metal element equivalent value. For example, in zinc oxide, a finely dispersed material is used as an electrodeposition coating composition, and the electrodeposition coating composition is centrifuged at 12000 rpm × 30 minutes with a centrifuge (H-200N: manufactured by Kokusan Centrifuge Co., Ltd.). The concentration of the dissolved metal compound (A) relative to the electrodeposition coating composition was calculated by measuring the concentration of the supernatant liquid with fluorescent X-rays (ZSX Primus: manufactured by Rigaku Corporation).

  All of the coated products obtained by applying the electrodeposition coating compositions of the examples had excellent CCT test results and were confirmed to have excellent corrosion resistance. The coated products of the examples were further excellent in coating film smoothness (coating appearance) and the stability of the electrodeposition coating composition. These examples also show that the electrodeposition coating composition of the present invention can form an electrodeposition coating film having excellent performance even on an object to be coated (untreated) that has not been subjected to chemical conversion treatment. In particular, in Examples other than Example 9, an electrodeposition coating film having excellent corrosion resistance was obtained despite the heating at a low temperature of 140 ° C. or lower.

In addition, when a chemical conversion treatment such as a zinc phosphate chemical conversion treatment in which a film grows from a crystal nucleus as a base point, the chemical conversion film is not sufficiently formed on the edge portion of the object to be coated. However, according to Example 20, even when an L-type spare blade subjected to zinc phosphate conversion treatment was used, the edge portion was obtained by using the electrodeposition coating composition of the present invention. It was found that corrosion in the glass was extremely difficult to occur and an excellent rust prevention effect was obtained.

  Comparative Examples 1 and 2 using an electrodeposition coating composition not containing the dissolved metal compound (A) had poor CCT test results and poor corrosion resistance.

  Comparative Example 3 is an example in which a metal nitrite (D), that is, calcium nitrite is not used, and defects are observed in the edge corrosion test and CCT.

  Comparative Example 4 is an example in which zinc is used as the metal of the dissolved metal compound (A), but the theoretical residual hydroxyl group in the case where the amine value resin and the blocked isocyanate curing agent react at the time of heat curing in the electrodeposition coating film. The value was less than 50, the CCT test result was bad, and the corrosion resistance was poor.

  Comparative Example 5 is an example in which a zinc phosphate chemical conversion treatment is applied to the article to be coated, but the dissolved metal compound (A) and the nitrite metal salt (D) are not blended, and the edge corrosivity is poor.

  By using the electrodeposition coating composition of the present invention, a coating film having excellent edge rust resistance can be obtained. Further, even when a steel sheet that is not subjected to chemical conversion treatment is used, there is an advantage that a coating film excellent in corrosion resistance, adhesion, and coating film smoothness (coating appearance) can be obtained. By using the electrodeposition coating composition of the present invention, it is possible to effectively use a steel sheet that is not subjected to chemical conversion treatment, and it is possible to reduce labor and cost spent for chemical conversion treatment.

Claims (6)

Dissolved metal compound (A) containing one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, Ni and Zr (provided that the dissolved metal compound (A) Except for the case of using two kinds of a dissolved metal compound (A1) in which the metal is Zn and a dissolved metal compound (A2) in which the metal is Zr), an aminated resin (B), and a curing agent (C). And an electrodeposition coating composition comprising a metal nitrite (D),
The aminated resin (B) has a number average molecular weight of 1,000 to 5,000, an amine value of 20 to 100 mgKOH / g, and a hydroxyl value of 50 to 400 mgKOH / g.
The curing agent (C) is a blocked isocyanate curing agent,
When the metal nitrite (D) is calcium nitrite or zinc nitrite, and the aminated resin (B) and the blocked isocyanate curing agent react during heat curing in the electrodeposition coating film The theoretical residual hydroxyl value in is 90 to 350 mg KOH / g.
Electrodeposition paint composition.   The electrodeposition coating composition according to claim 1, wherein the soluble metal compound (A) is zinc and has an ion concentration of 0.01 to 0.3% by mass.   The electrodeposition coating composition is further a chelating acid (which is at least one selected from the group consisting of sulfonic acid, organic phosphonic acid, organic carboxylic acid, amino acid, aminocarboxylic acid, sugar acid and carboxyl group-containing vinyl resin) The electrodeposition coating composition according to claim 1 or 2, comprising E).   The electrodeposition coating composition according to any one of claims 1 to 3, wherein the electrodeposition coating composition further contains an aminosilane compound (F).   The electrodeposition coating composition according to any one of claims 1 to 4, wherein the electrodeposition coating composition contains a plasticizer.   6. The metal species of the dissolved metal compound is one or more metals selected from the group consisting of Ti, Bi, Zn, Y, Nd, La, Ce, and Ni. Electrodeposition coating composition.