WO2015029757A1

WO2015029757A1 - Method for forming multilayer film

Info

Publication number: WO2015029757A1
Application number: PCT/JP2014/071096
Authority: WO
Inventors: 根本　幸宏; 松田　英樹; 飯島　英基
Original assignee: 関西ペイント株式会社
Priority date: 2013-08-30
Filing date: 2014-08-08
Publication date: 2015-03-05

Abstract

The present invention addresses the problem of providing: a method for forming a multilayer film that exhibits excellent finishing properties and corrosion resistance without affecting electrodeposition coatability even if part or all of a washing step is omitted after a chemical conversion treatment; and a coated article. The present invention provides a method for forming a multilayer film that comprises the following steps for forming a chemical conversion treatment film and an electrodeposition coating film on a metal object to be coated: a step (1) in which the metal object to be coated is immersed in a chemical conversion treatment liquid in order to form the chemical conversion treatment film; and a step (2) in which a part or all of a washing step is omitted and a cationic electrodeposition paint is used to perform electrodeposition coating of the metal object to be coated in order to form the electrodeposition coating film. The method for forming a multilayer film is characterized in that, when the total amount of resin solids is used as a reference, the cationic electrodeposition paint contains 40-88 mass% of an amino group-containing epoxy resin (A), 10-50 mass% of a blocked polyisocyanate (B), and 2-40 mass% of a pigment dispersion resin (C), and the quaternary ammonium salt concentration in the cationic electrodeposition paint is 0.03 mmol/g or less per resin solid content in the paint.

Description

Multi-layer coating formation method

[Cross-reference of related applications]
This application is filed in Japanese Patent Application No. 2013-180150 filed on August 30, 2013 and in Japanese Patent Application No. 2014-092916 filed on April 28, 2014 ( The entire disclosure of which is incorporated herein by reference).
The present invention is capable of electrodeposition coating without being affected by the solution adhered and / or deposited on the metal coating after chemical conversion treatment, even if a part or all of the water washing step is omitted after chemical conversion treatment. TECHNICAL FIELD The present invention relates to a method for forming a multilayer film that provides a coated article having excellent properties and corrosion resistance, and a coated article using the multilayer film formation method.

Conventionally, a chemical conversion treatment is performed on an industrial metal coating for the purpose of improving corrosion resistance and adhesion as a base treatment. However, the chemical conversion liquid contains a large amount of various ion components, and also contains a large amount of heavy metal components such as zinc, nickel, and manganese in order to improve the performance of the chemical conversion treatment film to be formed.

After performing the above chemical conversion treatment, if the electrodeposition coating is carried out using the cationic electrodeposition paint as it is, the excess chemical conversion solution that adheres to and deposits on the metal coating will be applied to the electrodeposition paintability, finish, and corrosion resistance. It is known to have an adverse effect.

Therefore, in a normal coating line, as shown in Fig. 1 below, "Degreasing-chemical conversion treatment-first water washing-second water washing-pure water water washing-electrodeposition coating-first water washing-second water washing-pure water water washing-baking drying As described above, a lot of man-hours and time are required for the washing process, and further, a large amount of equipment and costs are required for collecting, filtering, treating, and discarding the wastewater discharged in the washing process.

Patent Document 1 discloses a method for forming a multi-layered film that can reduce the process and save space by performing electrodeposition without performing water washing after the chemical conversion treatment. There is a description that even if the liquid is brought into the electrodeposition coating, which is the next step, a coated article having excellent finish and anticorrosion properties can be obtained without affecting the electrodeposition coating properties and coating film properties. However, depending on the composition of the electrodeposition paint, if the electrodeposition paint is used for the electrodeposition without washing with water, sufficient anticorrosion and finish may not be ensured.

Patent Document 2 defines a sodium ion concentration of an aqueous zinc nitrite solution used as an accelerator in a method of chemical conversion treatment by immersion treatment using an acidic zinc phosphate aqueous solution. In the paragraph [0016] of the specification, it is described that if the sodium ion concentration in the chemical conversion treatment tank is 10000 ppm by weight, a good chemical conversion treatment film can be obtained. The electrical conductivity also increases, the water washing process cannot be omitted, and it is difficult to save process and space.

In Patent Document 3, in the chemical conversion treatment method for obtaining a high-quality chemical conversion film, the electrical conductivity of the chemical conversion treatment liquid is 10 to 200 mS / cm (10,000 to 200,000 μS / cm) in paragraph [0063] of the specification. However, in the case of a chemical conversion treatment liquid with such a high electrical conductivity, a sufficient water washing process is essential, and the water washing process cannot be omitted. Is difficult.

JP 2009-149974 A JP 2001-323384 A Japanese Patent Laid-Open No. 6-2157

An object of the present invention is to provide a method for forming a multi-layer coating that enables process saving and space saving, and even if a part or all of the water washing process is omitted after the chemical conversion treatment, It is intended to provide a coated article that is excellent in finish and anticorrosion properties without affecting the surface.

As a result of earnest research, the present inventor has formed a chemical conversion treatment film on a metal object, and then electrodeposited, in a multilayer film forming method characterized by the fourth grade in a cationic electrodeposition paint. It has been found that by making the ammonium salt concentration within a specific range, it is possible to achieve both process saving, space saving and coating film performance, and the present invention has been completed.

That is, the present invention provides the following multilayer film forming method and coated article. Item 1. The following processes for forming a chemical conversion treatment film and an electrodeposition coating film on a metal object:
Step 1: a step of immersing a metal coating in a chemical conversion treatment solution to form a chemical conversion treatment film,
Step 2: In a multilayer film forming method including a step of forming an electrodeposition coating film by electrodeposition-coating the metal coating using a cationic electrodeposition coating,
The cationic electrodeposition coating composition is based on the total amount of resin solids, amino group-containing epoxy resin (A) 40 to 88 mass%, blocked polyisocyanate (B) 10 to 50 mass%, pigment dispersion resin (C) A method for forming a multilayer film, comprising 2 to 40% by mass, wherein the quaternary ammonium salt concentration in the cationic electrodeposition coating is 0.03 mmol / g or less per resin solid content in the coating.
Item 2. Item 2. The method for forming a multilayer film according to Item 1, wherein, in Step 2, part or all of the water washing step before electrodeposition coating is omitted.
Item 3. At least one resin used as the pigment dispersion resin (C) contains at least one selected from a sulfonium base and a tertiary ammonium base as a functional group, and is used as the pigment dispersion resin (C). Item 3. The method for forming a multilayer film according to Item 1 or 2, wherein a concentration of the quaternary ammonium salt per resin solid content of the total resin is 0.7 mmol / g or less.
Item 4. Any one of Items 1 to 3 above, wherein the conductivity of the solution adhering to and / or accumulating on the metal object is less than 10,000 μS / cm at the time of electrodeposition coating in Step 2 above. The method for forming a multilayer film according to claim 1.
Item 5. Item 5. The item according to any one of Items 1 to 4, wherein the sodium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution. A method for forming a multilayer film.
Item 6. Item 6. The item 1-5, wherein the potassium ion concentration of the solution adhering to and / or accumulating on the metal coating is less than 500 ppm, based on the mass of the solution. A method for forming a multilayer film.
Item 7. Item 7. The item according to any one of Items 1 to 6, wherein the calcium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution. A method for forming a multilayer film.
Item 8. Item 8. The magnesium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution, A method for forming a multilayer film.
Item 9. The chemical conversion treatment liquid is at least one metal compound selected from zirconium, titanium, cobalt, aluminum, vanadium, tungsten, molybdenum, copper, zinc, indium, bismuth, yttrium, iron, nickel, manganese, gallium, silver, and lanthanoid metal Item 9. The multilayer film formation according to any one of Items 1 to 8, wherein at least one metal compound component (M) comprising 30 to 20,000 ppm in terms of total metal amount (in terms of mass) is contained. Method.
Item 10. Item 10. The method for forming a multilayer film according to any one of Items 1 to 9, wherein the chemical conversion treatment solution contains a zirconium compound.
Item 11. Item 11. The multilayer coating formation according to any one of Items 1 to 10, wherein the chemical conversion treatment solution contains 0.01 to 40% by mass of a water-dispersible or water-soluble resin composition (P). Method.
Item 12. Item 12. The item 1 to item 11 above, wherein at least one selected from air blow, rocking, and rotation is performed on the metal object before the electrodeposition coating in step 2 is performed. A method for forming a multilayer film.
Item 13. 13. A coated article in which a multilayer coating is formed using the multilayer coating formation method according to any one of items 1 to 12.

The multilayer film forming method of the present invention is a method by which a coated article having excellent finish and anticorrosion properties can be obtained without affecting the electrodeposition coating properties even if part or all of the washing step is omitted after the chemical conversion treatment. It is. The multilayer film forming method of the present invention can omit part or all of the water washing step, thus enabling process saving and space saving, and reducing various wastewater treatment facilities and waste. Can do.

In the present invention, the reason why it is possible to achieve both the omission of the water washing step (part or all of the steps to save the process and save space) and the finish and anticorrosiveness is not sure, but the following The reason can be considered.

First, as a main reason, when part or all of the washing step is omitted, the conductivity of the solution adhering / depositing on the metal coating is high (adhering to the surface of the metal coating at a high concentration) When the electrodeposition coating is carried out using a cationic electrodeposition paint containing a quaternary ammonium base-containing compound in the deposited state), the quaternary ammonium base and components of the chemical conversion liquid are aggregated, and the electrical conductivity is high. Since the component remains in the multilayer film, it is considered that the finish and / or anticorrosion properties are inferior. In particular, when an ionic component such as sodium ion, potassium ion, calcium ion and / or magnesium ion of the solution adhering / depositing on the metal coating is contained at a specific concentration or more, the tendency is more remarkable. In addition, the reason other than the above is that extra chemical conversion treatment liquid (including sodium ions, potassium ions, calcium ions, magnesium ions, etc.) adhering to and deposited on the object to be coated is brought into the electrodeposition paint tank as impurities. In such a case, there is a possibility that the quaternary ammonium base contained in the cationic electrodeposition paint and the above-mentioned contaminants aggregate to deteriorate the finish and anticorrosion properties.

Therefore, as a method for forming a multilayer film of the present invention, at least the following two points are considered effective when some or all of the water washing step is omitted.
(1) A compound having a quaternary ammonium base is not contained in the cationic electrodeposition coating as much as possible. Furthermore, the functional group of the pigment dispersion resin (C), which is one of the components of the cationic electrodeposition paint, contains at least one selected from sulfonium bases and tertiary ammonium bases, and can form a quaternary ammonium base. Do not contain as much as possible.
(2) The concentration of sodium ion, potassium ion, calcium ion and / or magnesium ion contained in the solution adhering to and depositing on the metal coating is suppressed to lower the conductivity.

FIG. 1 is a schematic view showing a conventional method for forming a multilayer film.

One preferred embodiment of the present invention is as follows.

In a multi-layer coating formation facility comprising a chemical conversion treatment tank and an electrodeposition paint tank, a metal coating is immersed in a chemical conversion treatment tank filled with a chemical conversion treatment solution, and the metal coating is performed with or without energization. A chemical conversion film is formed on the object. Next, the present invention relates to a multilayer film forming method in which part or all of the washing step is omitted and the electrodeposition coating is performed by dipping in an electrodeposition coating tank filled with a specific cationic electrodeposition coating.
Details will be described below.

The metal coating used in the multilayer film forming method of the present invention is not particularly limited as long as it is a metal coating capable of electrodeposition coating, cold-rolled steel sheet, galvannealed steel sheet Galvanized steel sheet, electrogalvanized steel double-layer plated steel sheet, organic composite plated steel sheet, Al material, Mg material, etc., and these may be used alone or in combination of two or more metals. Alternatively, even an object to be coated in which two or more kinds of metals are combined can be suitably used.
Further, the metal coating may be optionally subjected to degreasing, surface adjustment, water washing and the like.

Chemical conversion liquid The composition of the chemical conversion liquid used in the method for forming a multilayer film of the present invention includes the following metal compound component (M) and optionally a water-dispersible or water-soluble resin composition (P). Is done.

Metal compound component (M)
The chemical conversion treatment liquid used in the method for forming a multilayer film of the present invention preferably contains 30 to 20,000 ppm of the total amount of metal (in terms of mass) of the metal compound component (M) from the viewpoint of corrosion resistance and finish.

Examples of the metal compound component (M) include zirconium compounds, titanium, cobalt, aluminum, vanadium, tungsten, molybdenum, copper, zinc, indium, bismuth, yttrium, iron, nickel, manganese, gallium, silver, and lanthanoid metals ( Lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium). The metal compound component (M) preferably contains a zirconium compound. These can be used alone or in combination of two or more.

The zirconium compound used in the metal compound component (M) is a compound that generates a zirconium-containing ion such as a zirconium ion, an oxyzirconium ion, or a fluorozirconium ion. As a compound that generates a zirconium ion, for example, a compound that generates an oxyzirconium ion Zirconyl nitrate, zirconyl acetate, zirconyl sulfate, etc .; examples of compounds that generate fluorozirconium ions include zirconium hydrofluoric acid, sodium zirconium fluoride, potassium zirconium fluoride, lithium zirconium fluoride, and ammonium zirconium fluoride. It is done. Among these, zirconyl nitrate and zirconium ammonium fluoride are particularly preferable.

Examples of compounds that generate titanium ions include titanium chloride, titanium sulfate, and compounds that generate fluorotitanium ions. Examples include titanium hydrofluoric acid, sodium titanium fluoride, potassium titanium fluoride, lithium titanium fluoride, and titanium fluoride. Ammonium etc. are mentioned. Among these, ammonium titanium fluoride is particularly preferable.

Examples of the compound that generates cobalt ions include cobalt chloride, cobalt bromide, cobalt iodide, cobalt nitrate, cobalt sulfate, cobalt acetate, and cobalt ammonium sulfate. Of these, cobalt nitrate is particularly preferred.

Examples of the compound that generates aluminum ions include aluminum phosphate, aluminum nitrate, aluminum carbonate, aluminum sulfate, aluminum acetate, aluminum formate, aluminum oxalate, aluminum lactate, aluminum malonate, aluminum tartrate, and aluminum ascorbate. . Of these, aluminum sulfate is particularly preferred.

Examples of the compound that generates vanadium ions include lithium orthovanadate, sodium orthovanadate, lithium metavanadate, potassium metavanadate, sodium metavanadate, ammonium metavanadate, sodium pyrovanadate, vanadyl chloride, and vanadyl sulfate. Among these, ammonium metavanadate is particularly preferable.

Examples of compounds that generate tungsten ions include lithium tungstate, sodium tungstate, potassium tungstate, ammonium tungstate, sodium metatungstate, sodium paratungstate, ammonium pentatungstate, ammonium heptungstate, sodium phosphotungstate. And barium borotungstate. Among these, ammonium tungstate is particularly preferable.

Examples of compounds that generate molybdenum ions include lithium molybdate, sodium molybdate, potassium molybdate, ammonium heptamolybdate, calcium molybdate, magnesium molybdate, strontium molybdate, barium molybdate, phosphomolybdic acid, and phosphomolybdic acid. Examples thereof include sodium and zinc phosphomolybdate.

Examples of compounds that generate copper ions include copper sulfate, copper (II) nitrate trihydrate, copper (II) ammonium sulfate hexahydrate, cupric oxide, and copper phosphate.
Examples of the compound that generates zinc ions include zinc acetate, zinc lactate, and zinc oxide.

Examples of the compound that generates indium ions include indium ammonium nitrate.

Examples of compounds that generate bismuth ions include inorganic bismuth-containing compounds such as bismuth chloride, bismuth oxychloride, bismuth bromide, bismuth silicate, bismuth hydroxide, bismuth trioxide, bismuth nitrate, bismuth nitrite, and bismuth oxycarbonate. Bismuth lactate, triphenyl bismuth, bismuth gallate, bismuth benzoate, bismuth citrate, bismuth methoxyacetate, bismuth acetate, bismuth formate, and bismuth 2,2-dimethylolpropionate.

Examples of the compound that generates yttrium ions include yttrium nitrate, yttrium acetate, yttrium chloride, yttrium sulfamate, yttrium lactate, and yttrium formate.

Compounds that produce iron ions include iron (II) chloride, iron (III) chloride, iron (III) ammonium citrate, iron (III) ammonium oxalate, iron (III) nitrate, iron (III) fluoride, sulfuric acid Examples thereof include iron (III) and ammonium iron (III) sulfate.

Compounds that produce nickel ions include nickel chloride (II), nickel acetate (II), nickel citrate (II), nickel oxalate (II), nickel nitrate (II), nickel sulfamate (II), nickel carbonate ( II), nickel sulfate (II), nickel fluoride (II) soot and the like. Compounds that produce manganese ions include manganese acetate (II), manganese acetate (III), manganese oxalate (II), manganese nitrate (II), manganese carbonate (II), manganese sulfate (II), manganese sulfate (II) Ammonium etc. are mentioned.

Examples of the compound that generates gallium ions include gallium nitrate.

Examples of compounds that generate silver ions include silver acetate (I), silver chloride (I), silver nitrate (I), and silver sulfate (I).

In the lanthanoid metal compound, examples of the compound that generates lanthanum ions include lanthanum nitrate, lanthanum fluoride, lanthanum acetate, lanthanum boride, lanthanum phosphate, and lanthanum carbonate; Cerium (III), cerium chloride (III), cerium acetate (III), cerium oxalate (III), ammonium cerium nitrate (III), diammonium cerium nitrate (IV), etc .; Examples of compounds that produce praseodymium ions include nitric acid Praseodymium, praseodymium sulfate, praseodymium oxalate and the like; Examples of compounds that generate neodymium ions include neodymium nitrate and neodymium oxide.

Further, the metal compound component (M) is optionally selected from alkali metals (lithium, sodium, potassium, rubidium, cesium, francium) and alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, radium). It is also possible to contain at least one metal compound.

The metal compound component (M) used in the present invention preferably contains at least one zirconium compound and aluminum nitrate, and more preferably contains at least one zirconium compound.

Water-dispersible or water-soluble resin composition (P)
The chemical conversion treatment solution used in the multilayer film forming method of the present invention can optionally contain 0.01 to 40% by mass of a water-dispersible or water-soluble resin composition (P).

Examples of the water-dispersible or water-soluble resin composition (P) include cationic resin compositions that can be cationized in an aqueous medium such as amino group, ammonium base, sulfonium base, and phosphonium base in the molecule. It is done.

In addition, an anionic resin composition having a group that can be anionized in an aqueous medium such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group in the molecule. Examples of the resin include epoxy resin, acrylic resin, polybutadiene resin, alkyd resin, and polyester resin.

Among these functional groups, the cationic resin composition having an amino group in the molecule has no effect even if it is mixed into the cationic electrodeposition paint as a contaminant, and is coated with the chemical conversion treatment liquid. The coated metal object is also preferred for suppressing rusting while being transferred to the cationic electrodeposition coating tank and for improving the corrosion resistance of the resulting coated article. The cationic resin composition having an amino group is not particularly limited, but an amino group-containing epoxy resin, polyallylamine, Mannich modified aminated phenol resin, and the like are preferable, and these may be used alone or in combination of two. The above can be used in combination. The amine value of the resin is preferably in the range of 30 to 150 mg KOH / g resin solids, and more preferably in the range of 60 to 130 mg KOH / g resin solids.

The water-dispersible or water-soluble resin composition (P) can be used for the preparation of a chemical conversion treatment liquid by appropriately adding a neutralizing agent and dispersing in water with deionized water to give an emulsion.

As a component of the chemical conversion treatment solution, in addition to the above-mentioned resin, a resin or compound containing a hydroxyl group and an oxyethylene chain as a nonionic and highly polar functional group in the molecule, and capable of being dispersed in water or water-soluble in an aqueous medium Can be used. Specific examples of such resins and compounds include polyvinyl alcohol, polyoxyethylene, polyvinylpyrrolidone, polyoxypropylene, hydroxyethylcellulose, hydroxypropylmethylcellulose, and the like. These may be used alone or in combination of two or more. It can be used in combination.

When the chemical conversion treatment solution contains the resin composition (P), rusting on the object to be coated can be suppressed during the transfer to the electrodeposition coating tank.

Preparation of chemical conversion treatment solution used in the multilayer film forming method of adjusting the invention of the chemical conversion treatment solution is not particularly limited, for example, described below (1) can be carried out by the method to (3).
(1) Add metal compound component (M) to deionized water and / or water dispersible or water-soluble resin composition (P), add neutralizer as appropriate, and then add deionized water to adjust. how to.
(2) A method of adjusting the metal compound component (M) by adding deionized water and / or water-dispersed or water-soluble resin composition (P).
(3) A method in which a metal compound component (M) and / or a resin composition (P) dispersed in water or water-solubilized is added to a chemical conversion treatment solution prepared in advance, and deionized water is further added thereto for adjustment.

In the chemical conversion treatment liquid, the metal compound component (M) is generally 30 to 20,000 ppm, preferably 50 to 10,000 ppm, more preferably 100 to 5,000 ppm, and even more particularly preferable in terms of the total metal amount (in terms of mass). Is contained in an amount of 150 to 2,000 ppm, and the water-dispersible or water-soluble resin composition (P) is optionally added in an amount of 0.01 to 40% by mass, preferably 0. It can be contained in an amount of 02 to 10% by mass, more preferably 0.03 to 1% by mass. The pH is preferably in the range of 1.0 to 8.0, preferably 3.0 to 7.0.

In addition, as the chemical conversion treatment liquid used in the method for forming a multilayer film of the present invention (step 1), it is preferable that the sodium ion concentration contained in the chemical conversion treatment liquid is usually less than 2,000 ppm on a mass basis. is there. If the sodium ion concentration is higher than 2,000 ppm, the paintability, finish of the coating film, and anticorrosion in electrodeposition coating may be inferior when part or all of the washing step is omitted. The concentration of sodium ions contained in the chemical conversion treatment liquid is usually less than 2,000 ppm, preferably less than 1,000 ppm, more preferably less than 500 ppm, and even more preferably less than 100 ppm on a mass basis. Is preferred.

Examples of a route in which sodium ions are contained in the chemical conversion treatment liquid include, for example, water as a raw material, an accelerator (such as sodium nitrite), the above-described metal compound component (M), a neutralizing agent, and a degreasing agent used in the previous step. The thing brought in from a liquid and washing water etc. can be considered. For example, when the chemical conversion treatment solution is continuously used in a production line or the like, the chemical conversion treatment component gradually diminishes. Therefore, the concentration is usually adjusted by adding a replenishment solution as needed. However, impurity components (Na ions and the like) contained in a trace amount in the replenishing solution or components brought in from the previous process gradually accumulate in the chemical conversion treatment solution, which adversely affects performance. Further, when the impurity component adheres or accumulates on the object to be coated at a certain concentration or more and is brought into the electrodeposition paint bath as the next step, the performance is adversely affected. In the present application, even when continuous production is performed, good performance can be obtained by keeping the specific ion concentration of the chemical conversion treatment liquid below a certain level.

For the same reason as described above, the potassium ion concentration, calcium ion concentration, and magnesium ion concentration contained in the chemical conversion treatment liquid are also usually less than 2,000 ppm, preferably less than 1,000 ppm, on a mass basis. Yes, more preferably less than 500 ppm, still more preferably less than 100 ppm.

The preferable ranges of sodium ion concentration, potassium ion concentration, calcium ion concentration, and magnesium ion concentration contained in the chemical conversion treatment solution are particularly preferable ranges when all water washing steps are omitted.

In addition, about the sodium ion concentration in a chemical conversion liquid, potassium ion concentration, calcium ion concentration, and magnesium ion concentration, atomic absorption spectrometry using an atomic absorption analyzer (brand name: Zeeman atomic absorption photometer, the product made by HITACHI). It can ask for.

The methods for forming the conversion coating of the chemical conversion film is not particularly limited, for example, a metal object to be coated, the chemical conversion treatment tank filled with a chemical conversion treatment liquid, usually 10 to for 360 seconds, preferably 50 to A method (1) of immersing for 300 seconds, more preferably 70 to 240 seconds to form a chemical conversion coating on the metal coating, immersing the metal coating in a chemical conversion bath filled with a chemical conversion solution, Examples include a method (2) in which a metal coating is used as a cathode, and a current is normally applied at 1 to 50 V for 10 to 360 seconds, preferably 2 to 30 V for 30 to 180 seconds. In the method of the present invention, a multilayer film having suppression of appearance unevenness and high anticorrosion properties can be obtained even in the method (1) in which no energization is performed.

In addition, as a precipitation mechanism of a chemical conversion treatment film, a hydrolysis reaction occurs due to a pH increase in the vicinity of a metal object by immersion or energization, and the metal ion species in the chemical conversion treatment solution is hardly soluble (metal oxide And / or a part of the resin composition (P)) is deposited on the metal article to form a chemical conversion film containing the metal compound component (M) and / or the resin composition (P). The

In addition, the metal coating on which the chemical conversion film is formed is appropriately set before electrodeposition coating, and then immersed in a cation electrodeposition paint tank filled with the cation electrodeposition paint to perform electrodeposition coating. An electrodeposition coating film can be formed on the chemical conversion film. In that case, in this invention, a part or all of the water washing process conventionally performed 2 steps or more before electrodeposition coating can be abbreviate | omitted.

In the present specification, “a part or all of the water washing step is omitted” means that at least one water washing step consisting of industrial water washing and / or clean water washing and pure water can be omitted. This can be appropriately handled according to the required coating film performance. For example, a water washing process in which industrial water washing and clean water washing are omitted and pure water washing is performed only once corresponds to “a part or all of the water washing process is omitted” and is preferable. Therefore, “to omit part or all of the water washing step” means, for example, (i) washing with industrial water washing and / or water washing, and (ii) washing with only pure water, Or (i) indicates that neither of (ii) is performed. In the present invention, although the steps (i) and (ii) are performed together, the amount of water used in each step is reduced so that the total amount of water used is the steps (i) and (ii). The method that is equivalent to omitting at least one of the above is substantially the same as omitting at least one of the steps (i) and (ii) from the viewpoint of the amount of water used. It is included in a method in which part or all of the washing step is omitted. In addition, as described above, the method of the present invention includes a water washing process in order to reduce the time and cost of the water washing process, including facilities and expenses for collecting, filtering, treating, and discarding the wastewater discharged in the water washing process. It relates to a method in which part or all of the method is omitted. Therefore, when the above formally corresponds to the above example, for example, the method of performing only the pure water cleaning of (ii) without performing (i) is equal to or more than performing (i) and (ii). It is clear that the method of sufficiently washing with pure water does not fall under the scope of the present invention and does not correspond to “a part of the washing process is omitted”. In addition, for example, conventionally, the water washing step of the object to be coated after the chemical conversion treatment has been performed in order to wash away the chemical conversion liquid, so that the chemical conversion liquid is sufficiently washed away from the object to be coated, Management is performed by measuring the electrical conductivity of the water after the final water washing step. For example, it is managed that the chemical conversion liquid has been sufficiently washed away from the object to be coated when the electric conductivity of the water after the water washing in the final water washing step becomes 50 μS / cm or less. Therefore, the water washing method in which the electric conductivity of the water after the final water washing step is lower than the electric conductivity of the water after the conventional water washing step does not fall under “Omit part or all of the water washing step”. it is obvious.

As the water washing method, there are an immersion method and a spray method (spray spray method, shower spray method), and any method can be suitably used in the present invention. From the viewpoint of reducing waste, a water washing step in which only spray-type water washing is performed is preferable, and a water washing step in which spray-type water washing is performed only once is more preferable. In the spray-type water washing, excess chemical conversion treatment liquid can be removed by spraying water on the surface of the coating material subjected to chemical conversion treatment for usually 1 to 120 seconds, preferably 2 to 60 seconds. As the spray-type water washing, when the shape of an object to be coated is complicated (for example, an automobile frame, etc.), it is not possible to spray directly on all surfaces, so that only the outer surface where the finished appearance is most important can be sprayed. it can. Therefore, “a part or all of the water washing step is omitted” includes, for example, a method including a step of spraying water for 120 seconds or less, preferably 60 seconds or less. The above method includes a method in which no water washing is performed.

Also, from the viewpoint of further process and space saving, wastewater treatment and waste reduction, all water washing processes such as industrial water washing, clean water washing and pure water washing, including immersion type and spray type, are omitted. It is particularly preferred.

The setting conditions performed before the electrodeposition coating are usually 0 to 80 ° C., preferably 5 to 50 ° C., more preferably 10 to 40 ° C., and usually 10 to 30 minutes, preferably 20 seconds to By applying a setting time of 20 minutes, more preferably 30 seconds to 15 minutes, it is possible to remove excess chemical conversion treatment liquid adhering to the metal object, and as a result, the electrodeposition coating property is good. A multi-layered film having excellent finish and / or anticorrosion properties can be formed.

Further, during the setting, the metal coating object is appropriately subjected to at least one selected from air blow, rocking, and rotation, thereby removing as much as possible the excess chemical conversion treatment liquid deposited and deposited on the metal coating object. be able to.

As the air blow, the air pressure on the surface of the object to be coated is usually 0.01 to 1.0 MPa, preferably 0.05 to 0.5 MPa, usually 1 second to 10 minutes, preferably 2 seconds to 3 minutes. By spraying air at a temperature of usually 0 to 80 ° C., preferably 10 to 60 ° C., the excess chemical conversion treatment liquid on the object to be coated can be removed.

Subsequently, the metal coating on which the obtained chemical conversion coating is formed is immersed in a cationic electrodeposition tank filled with a specific cationic electrodeposition coating, and energized to perform electrodeposition coating on the chemical conversion coating. .

In the present invention, by setting the quaternary ammonium salt concentration in the cationic electrodeposition coating within the above range, the electric conductivity of the solution adhering to and / or stagnating on the metal coating immediately before the electrodeposition coating is performed. Is 10,000 μS / cm or more (for example, 10,000 to 12,000 μS / cm), it is possible to obtain a multi-layered film having high anticorrosion properties by suppressing uneven appearance.

However, in the present invention, it is preferable that the conductivity of the solution adhering to and / or accumulating on the metal coating immediately before the electrodeposition coating is in a range of less than 10,000 μS / cm. More preferably, the range is higher than 60 μS / cm and lower than 7,000 μS / cm, more preferably higher than 60 μS / cm and lower than 5,000 μS / cm, and particularly preferably. The range is preferably higher than 60 μS / cm and lower than 2,000 μS / cm. In the present invention, “at the time of electrodeposition coating” means “just before electrodeposition coating”. And “immediately before electrodeposition coating” means that after performing the above-mentioned chemical conversion treatment, optionally washing with water, and before immersing the metal coating on which the chemical conversion treatment film is formed in the cationic electrodeposition bath. means.

In order to reduce the electrical conductivity, a sufficient water washing process is required, and it is difficult to save process and space. Moreover, when the electrical conductivity is high beyond the above range, the finish and anticorrosive properties of the resulting multilayer film are inferior.

The sodium ion concentration of the solution adhering to and / or staying on the metal coating immediately before electrodeposition coating is usually less than 500 ppm, preferably less than 200 ppm, based on the mass of the solution. More preferably, it is less than 100 ppm, more preferably less than 50 ppm, and still more preferably less than 10 ppm.

Similarly, the potassium ion concentration, calcium ion concentration, and magnesium ion concentration of the solution adhering to and / or accumulating on the metal object immediately before electrodeposition coating are usually less than 500 ppm on a mass basis. It is preferably less than 200 ppm, more preferably less than 100 ppm, even more preferably less than 50 ppm, and even more preferably less than 10 ppm.

Cationic electrodeposition paint The cationic electrodeposition paint used in the method for forming a multilayer film of the present invention (step 2) comprises, as a resin component, an amino group-containing epoxy resin (A), a blocked polyisocyanate (B), and a pigment dispersion resin (C The amino group-containing epoxy resin (A) is usually 40 to 88% by mass, preferably 45 to 80% by mass, more preferably 50 to 75% by mass, based on the total amount of resin solids. %, The blocked polyisocyanate (B) is usually 10 to 50% by mass, preferably 15 to 45% by mass, more preferably 20 to 40% by mass, and the pigment dispersion resin (C) is usually It is contained in the range of 2 to 40% by mass, preferably 3 to 30% by mass, more preferably 4 to 20% by mass. In the present invention, the concentration of the quaternary ammonium salt in the cationic electrodeposition coating is usually 0.03 mmol / g or less, preferably 0.02 mmol / g or less, based on the resin solid content in the coating. Preferably it is 0.01 mmol / g or less. If this range is exceeded, the quaternary ammonium base and the components of the chemical conversion solution are aggregated, resulting in poor finish and / or anticorrosive properties.

Amino group-containing epoxy resin (A)
The amino group-containing epoxy resin (A) can be obtained by reacting the epoxy resin (a1), the amine compound (a2), and optionally a modifier, for example, (1) epoxy resin and Adducts with primary amine compounds, secondary amine compounds, or primary and secondary mixed amine compounds (see, for example, US Pat. No. 3,984,299); (2) epoxy resin and ketiminated Adducts with amine compounds (see, for example, US Pat. No. 4,017,438); (3) Reactions obtained by etherification of epoxy resins with hydroxy compounds having primary amino groups ketiminated An amino group-containing epoxy resin such as a product (for example, see JP-A-59-43013) can be mentioned.

Epoxy resin (a1)
The epoxy resin (a1) used for the production of the amino group-containing epoxy resin (A) is a compound having at least one, preferably two or more epoxy groups in one molecule, and its molecular weight is generally at least 300, Preferably a number average molecular weight in the range of 400 to 4,000, more preferably in the range of 800 to 2,500 and an epoxy equivalent weight in the range of at least 160, preferably 180 to 2,500, more preferably 400 to 1,500. What has it is suitable, The epoxy resin obtained by reaction of a polyphenol compound and an epihalohydrin is especially preferable.

Examples of the polyphenol compound used for forming the epoxy resin (a1) include bis (4-hydroxyphenyl) -2,2-propane [bisphenol A] and bis (4-hydroxyphenyl) methane [bisphenol F]. Bis (4-hydroxycyclohexyl) methane [hydrogenated bisphenol F], 2,2-bis (4-hydroxycyclohexyl) propane [hydrogenated bisphenol A], 4,4′-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-tert-butyl-phenyl) -2,2-propane, bis (2-hydroxynaphthyl) methane Tetra (4-hydroxyphenyl) -1,1,2,2-ethane 4,4'-dihydroxydiphenyl sulfone, phenol novolak, and the like can be illustrated cresol novolak, they may be used in combination singly or two or more.

Further, as the epoxy resin (a1) obtained by the reaction of the polyphenol compound and epichlorohydrin, a resin represented by the following formula derived from bisphenol A is particularly preferable.

Here, n = 0 to 8 are preferable.

Examples of the commercially available epoxy resin (a1) include those sold by Mitsubishi Chemical Corporation under the trade names jER828EL, jER1002, jER1004, and jER1007.

Further, the bisphenol type epoxy resin is, for example, a resin obtained by condensing epichlorohydrin and bisphenol up to a high molecular weight in the presence of a catalyst such as an alkali catalyst, and optionally epichlorohydrin and bisphenol. Any of resins obtained by condensing into a low molecular weight epoxy resin in the presence of a catalyst and polyaddition reaction of the low molecular weight epoxy resin and bisphenol may be used.

In this specification, the number average molecular weight and the weight average molecular weight are the retention time (retention capacity) measured using a gel permeation chromatograph (GPC) and the retention time of a standard polystyrene with a known molecular weight measured under the same conditions. (Retention capacity) is a value obtained by converting to the molecular weight of polystyrene. Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” are used as columns. ”And“ TSKgel G-2000HXL ”(trade names, all manufactured by Tosoh Corporation), and can be measured under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, and detector RI. it can.

Amine compound (a2)
The amine compound (a2) which is a raw material of the amino group-containing epoxy resin (A) is not particularly limited as long as it is an amine compound having reactivity with the epoxy resin (a1). For example, monomethylamine, dimethylamine Mono-alkylamines such as monoethylamine, diethylamine, dipropylamine, dibutylamine, dihexylamine, dioctylamine, monoisopropylamine, diisopropylamine, monobutylamine, monooctylamine, methylbutylamine, dibutylamine; Monoethanolamine, N-methylethanolamine, N-ethylethanolamine, diethanolamine, mono (2-hydroxypropyl) amine, di (2-hydroxypropyl) amine, N-butylethanolamine Dipropanolamine, monomethylaminoethanol, N- (2-hydroxypropyl) ethylenediamine, 3-methylamine-1,2-propanediol, 3-tert-butylamino-1,2-propanediol, N-methylglucamine, Alkanolamines such as N-octylglucamine; polymethylenediamine, polyetherdiamine, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, dimethylaminopropylamine, diethylenetriamine, diethylaminopropylamine, dipropylenetriamine, Dibutylene triamine, bis (hexamethylene) triamine, bis (4-aminobutyl) amine, triethylenetetramine, tetraethylenepentamine, pen Alkylene polyamines such as ethylene hexaamine; aromatics such as mensendiamine, isophoronediamine, bis (4-amino-3-methylcyclohexyl) methane, metaxylylenediamine, metaphenylenediamine, naphthylenediamine, dimethylaminomethylbenzene, or Alicyclic polyamines; polyamines having a heterocyclic ring such as piperazine, 1-methylpiperazine, 3-pyrrolidinol, 3-piperidinol, 4-pyrrolidinol; 1 to 30 mol of an epoxy group-containing compound is added to 1 mol of the polyamine. Polyepoxy-added polyamine obtained by the above-described process; a polyamide resin molecule formed by condensation of the polyamine with an aromatic acid anhydride, cycloaliphatic acid anhydride, aliphatic acid anhydride, halogenated acid anhydride and / or dimer acid 1 or more inside Polyamide polyamines containing the above primary or secondary amines; ketiminated amines obtained by reacting one or more primary or secondary amines in the above polyamines with a ketone compound; Species can be used alone or in combination of two or more. The ketone compound for producing the ketiminated amine is not particularly limited as long as it reacts with the primary or secondary amine of the polyamine to form a ketimine compound and further hydrolyzes in the aqueous coating composition. For example, methyl isopropyl ketone (MIPK), diisobutyl ketone (DIBK), methyl isobutyl ketone (MIBK), diethyl ketone (DEK), ethyl butyl ketone (EBK), ethyl propyl ketone (EPK), dipropyl ketone (DPK) And methyl ethyl ketone (MEK). Of these, methyl isobutyl ketone (MIBK) is preferable. These ketones can be used alone or in combination of two or more.

The amine value of the amino group-containing epoxy resin (A) is preferably 40 to 80 mgKOH / g, more preferably 45 to 65 mgKOH / g, from the viewpoint of dryness unevenness and anticorrosion of the coating film.

Modifier The amino group-containing epoxy resin (A) may be optionally modified with a modifier. Such a modifier is not particularly limited as long as it is a resin or compound having reactivity with the epoxy resin (a1). For example, acetic acid, propionic acid, butyric acid, valeric acid, acrylic acid, oleic acid, glycolic acid, Acidic compounds such as lactic acid, benzoic acid, gallic acid, fatty acid, dibasic acid, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, n-octanol, 2-ethylhexanol, Monohydric alcohols such as dodecyl alcohol, stearyl alcohol, benzyl alcohol, polyols, polyether polyols, polyester polyols, polyamidoamines, polyisocyanate compounds, lactones such as γ-butyrolactone and ε-caprolactone, lactos such as ε-caprolactone Examples include compounds obtained by reacting polyisocyanates with polyisocyanate compounds, acrylic monomers, compounds obtained by polymerization reaction of acrylic monomers, xylene formaldehyde compounds, etc., and these can be used alone or in combination of two or more. .

The reaction with the above-mentioned epoxy resin (a1), amine compound (a2), and optional modifier is usually carried out in an appropriate organic solvent at about 80 to about 170 ° C., preferably about 90 to about The reaction can be performed at a temperature of 150 ° C. for about 1 to 6 hours, preferably about 1 to 5 hours.

Examples of the organic solvent include hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, and the like. Ketones; Amides such as dimethylformamide and dimethylacetamide; Alcohols such as methanol, ethanol, n-propanol and iso-propanol; Ether alcohols such as ethylene glycol monobutyl ether and diethylene glycol monoethyl ether; or these organic solvents Of the mixture.

The use ratio of the above modifier is not strictly limited, and can be appropriately changed depending on the use of the cationic electrodeposition coating composition, but from the viewpoint of improving finish and anticorrosion properties, amino group-containing A suitable range is 3 to 50% by weight, preferably 5 to 30% by weight, based on the solid content of the epoxy resin (A).

The amino group-containing epoxy resin (A) used in the present invention is not particularly limited. In addition to the above, an amino group-containing epoxy resin obtained by reacting an amino group-containing compound with an epoxy resin containing an oxazolidone ring ( For example, JP-A-5-306327); an amino group-containing modified epoxy resin obtained by reacting an epoxy resin having an alkylene oxide structure with an amino group-containing compound (for example, JP-A-2011-847723); A xylene formaldehyde resin-modified amino group-containing epoxy resin (for example, JP-A No. 2003-221547) obtained by reacting a xylene formaldehyde resin and an amino group-containing compound can also be optionally used as appropriate. Or in combination of two or more

Blocked polyisocyanate (B)
The blocked polyisocyanate (B) is a product obtained by an addition reaction between a polyisocyanate compound and an isocyanate blocking agent. As the polyisocyanate compound used in the blocked polyisocyanate (B), known compounds can be used without any particular limitation. For example, tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,2'- Aromatic polyisocyanate compounds such as diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, crude MDI [polymethylene polyphenylisocyanate]; alicyclic rings such as bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate Polyisocyanate compounds; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and methylene diisocyanate Compound; cyclic polymer or biuret of these polyisocyanate compounds; or combinations thereof.

From the viewpoint of improving anticorrosion properties, it is particularly preferable to use aromatic polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, crude MDI, and the like. preferable.

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

As the isocyanate blocking agent used in the blocked polyisocyanate (B), known ones can be used without particular limitation. For example, oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol, para-t-butylphenol Phenol compounds such as cresol; alcohol compounds such as n-butanol, 2-ethylhexanol, phenyl carbinol, methyl phenyl carbinol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, ethylene glycol, propylene glycol; ε-caprolactam Lactam compounds such as γ-butyrolactam; dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone And the like, and these can be used singly or in combination of two or more.

Resin for pigment dispersion (C)
In the pigment dispersion resin (C), at least one resin used as the pigment dispersion resin contains at least one selected from sulfonium base and tertiary ammonium base as a functional group, and the pigment dispersion resin ( The concentration of quaternary ammonium salt per resin solid content obtained by adding all the resins used as C) is usually 0.7 mmol / g or less, preferably 0.5 mmol / g or less, more preferably 0.3 mmol. If it is / g or less, More preferably, if it is the range of 0.1 mmol / g or less, a well-known thing can be used. For example, an epoxy resin or acrylic resin having a hydroxyl group and a cationic group, a surfactant, or a tertiary ammonium salt type epoxy resin, a quaternary ammonium salt type epoxy resin, a tertiary sulfonium salt type epoxy resin, a quaternary sulfonium salt type An epoxy resin, a quaternary phosphonium base type epoxy resin, etc. are mentioned, These can be used individually by 1 type or in combination of 2 or more types.

In addition, the tertiary ammonium base described in the present invention is a functional group that is tertiary by neutralizing one part or all of the tertiary amino group with an acid.

A pigment dispersion paste can be obtained by dispersing the pigment with the pigment dispersion resin (C).

Other components of the cationic electrodeposition coating The cationic electrodeposition coating of the present invention is optionally made by reacting an epoxy resin with a polyhydric alcohol as a resin component other than the above (A), (B) and (C). Known products such as a modified epoxy resin having substantially no amino group and a polyester resin obtained by reacting a polybasic acid and a polyhydric alcohol can be contained.
When the cationic electrodeposition paint contains a modified epoxy resin and / or a polyester resin, the content is usually 3 based on the total solid content of 100 parts by weight of the components (A), (B) and (C). It is in the range of ˜50 parts by mass, preferably 10 to 45% by mass.

The above cationic electrodeposition coating is optionally further obtained by sufficiently mixing various additives such as a surfactant and a surface conditioner, water, an organic solvent, a neutralizing agent, etc., and making it water-soluble or water-dispersed. Can do.

As the neutralizing agent, known organic acids and inorganic acids can be used without particular limitation, and formic acid, lactic acid, acetic acid or a mixture thereof is particularly preferable.

As the pigment dispersion paste, pigments such as colored pigments, rust preventive pigments and extender pigments are dispersed in advance in fine particles, for example, a pigment dispersion resin (C), a neutralizing agent and pigments are blended. The pigment dispersion paste can be prepared by dispersing in a dispersion mixer such as a ball mill, sand mill, or pebble mill.

The pigments can be used without particular limitation, for example, colored pigments such as titanium oxide, carbon black, bengara, etc .; extender pigments such as clay, mica, barita, calcium carbonate, silica; aluminum phosphomolybdate, aluminum tripolyphosphate, And anticorrosive pigments such as zinc oxide (zinc white).

Furthermore, a bismuth compound can be included for the purpose of inhibiting corrosion. Examples of the bismuth compound include bismuth oxide, bismuth hydroxide, basic bismuth carbonate, bismuth nitrate, bismuth silicate, and organic acid bismuth such as bismuth lactate and bismuth salicylate.

Also, for the purpose of improving coating film curability, for example, organic tin compounds such as dibutyltin dibenzoate, dioctyltin oxide, dibutyltin oxide and the like can be used.

Electrodeposition coating The cationic electrodeposition paint used in the method for forming a multilayer film according to the present invention (step 2) omits part or all of the water-washing process on the metal coating on which the chemical conversion treatment film has been formed. can do. In the electrodeposition coating, generally, a cationic electrodeposition paint is diluted with deionized water or the like, and the solid content concentration is about 5 to 40% by mass, preferably 8 to 25% by mass, and the pH is 1.0 to 1.0%. A coating bath in the range of 9.0, preferably 3.0 to 7.0 is prepared, and further, the substrate is energized as a cathode under conditions of a bath temperature of 15 to 35 ° C. and a load voltage of 100 to 400 V. be able to.

After electrodeposition coating, in order to remove the cationic electrodeposition paint that has usually adhered to the object, ultrafiltration (UF filtrate), reverse osmosis permeate (RO water), industrial water, pure water, etc. Thoroughly washed with water.

The film thickness of the electrodeposition coating film obtained by applying the cationic electrodeposition coating is not particularly limited, but is generally 5 to 40 μm, preferably 10 to 30 μm, based on the dry coating film. Can be within range. The coating film is baked and dried at a temperature of 110 to 200 ° C., preferably 140 to 180 ° C., on the surface of the coating using a drying facility such as an electric hot air dryer or a gas hot air dryer. The time can be set by heating the electrodeposition coating film for 10 to 180 minutes, preferably 20 to 60 minutes. A cured coating film can be obtained by baking and drying.

Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples, but the present invention is not limited thereto. In each example, “part” means mass part, “%” means mass%, and “ppm” means mass ppm.

Manufacture example 1 of chemical conversion treatment liquid
While the deionized water was vigorously stirred with a disper, hexafluorozirconic acid and aluminum nitrate, calcium nitrate and potassium nitrate previously diluted with deionized water were blended.

Furthermore, it dilutes using clean water and / or deionized water, and mix | blends nitric acid, sodium nitrate, ammonium nitrate, magnesium nitrate, hydrofluoric acid, ammonia, and / or sodium hydroxide, and finally pH is 3. 8. The chemical conversion solution X-1 was obtained by adjusting the metal elements to 600 ppm zirconium ions, 120 ppm aluminum ions, 85 ppm sodium ions, 85 ppm potassium ions, 85 ppm calcium ions, and 85 ppm magnesium ions. It was.

Production Examples 2-31
Except for the composition shown in Table 1 below, compounding was conducted in the same manner as in Production Example 1 to obtain chemical conversion liquids X-2 to 31.

In addition, all the compounding quantities in a table | surface are solid content concentration (ppm) of a mass unit.
(Note 1) P-1: PAA-01 (trade name, manufactured by Nitto Boseki Co., Ltd., polyallylamine, weight average molecular weight 1,600)
(Note 2) P-2: Mannich-modified aminated phenol resin [Into a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, Marcalinker S-2P (trade name, manufactured by Maruzen Petrochemical Co., Ltd., Poly- 120 parts of 4-vinylphenol) and 120 parts of ethylene glycol monobutyl ether were added and the temperature was raised to 90 ° C. to dissolve poly-4-vinylphenol. Subsequently, 35 parts of monomethyl ether amine, 40 parts of 37% formalin and 10 parts of ethylene glycol monobutyl ether were added and reacted at 90 ° C. for 4 hours, and then ethylene glycol monobutyl ether was further added to adjust the solid content to 40%. ].

Production Example 32
Zinc ion: 1,500ppm
Nickel ion: 500ppm
Phosphate ion: 13,500ppm
Fluorine ion: 500ppm
Nitrate ion: 6,000ppm
Nitrite ion: 100ppm
Sodium ion: 85ppm
Calcium ion: 85ppm
Potassium ion: 85ppm
Magnesium ion: 85ppm
A chemical conversion solution X-32 having the above composition was prepared.

Production Example 33
Zinc ion: 1,500ppm
Nickel ion: 500ppm
Phosphate ion: 13,500ppm
Fluorine ion: 500ppm
Nitrate ion: 6,000ppm
Nitrite ion: 100ppm
Sodium ion: 300ppm
Calcium ion: 300ppm
Potassium ion: 300ppm
Magnesium ion: 300ppm
A chemical conversion solution X-33 having the above composition was prepared.

Production and production example 34 of amino group-containing epoxy resin (A)
To a flask equipped with a stirrer, thermometer, nitrogen inlet tube and reflux condenser, add 1200 parts of jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin), 500 parts of bisphenol A and 0.2 part of dimethylbenzylamine. The reaction was continued at 130 ° C. until the epoxy equivalent was 850.

Next, 160 parts of diethanolamine and 65 parts of a ketimine product of diethylenetriamine and methyl isobutyl ketone were added and reacted at a temperature of 120 to 130 ° C. for 3 hours. Then, 480 g of ethylene glycol monobutyl ether was added, and an amino group having a solid content of 80% was added. A contained epoxy resin A-1 was obtained.

Production and production example 35 of blocked polyisocyanate (B)
In a reaction vessel, 270 parts of Cosmonate M-200 (trade name, manufactured by Mitsui Chemicals, Crude MDI, NCO group content: 31.3%) and 127 parts of methyl isobutyl ketone were added and heated to 70 ° C. In this, 236 parts of ethylene glycol monobutyl ether was added dropwise over 1 hour, and then the temperature was raised to 100 ° C., sampled over time while maintaining this temperature, and absorption of unreacted isocyanate groups by infrared absorption spectrum measurement As a result, it was confirmed that blocked polyisocyanate B-1 having a resin solid content of 80% was obtained.

Production and Production Example 36 for Pigment Dispersing Resin (C)
To a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin) 1010 parts, bisphenol A 390 parts, Placcel 212 (trade name, polycaprolactone) Diol, Daicel Chemical Industries, Ltd., 240 parts by weight average molecular weight 1,250) and 0.2 parts dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent was about 1090. Next, 150 parts of ethylene glycol monobutyl ether, 105 parts of diethanolamine and 34 parts of N-methylethanolamine were added and reacted at 140 ° C. until the epoxy group disappeared. Next, ethylene glycol monobutyl ether was added to adjust the solid content to obtain a pigment-dispersing resin C-1 containing a tertiary ammonium base having a solid content of 60%.

Production Example 37
In a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, 450 parts of nonylphenol, CNE195LB (trade name, manufactured by Changchun Japan Co., Ltd., cresol type novolac epoxy resin, glycidyl etherified product of novolac type phenol resin) 960 parts Was gradually heated with mixing and stirring, and reacted at 160 ° C. for 2 hours. Next, 430 parts of ε-caprolactone was charged, and the temperature was raised to 170 ° C. and reacted for 2 hours. Subsequently, 200 parts of ethylene glycol monobutyl ether, 105 parts of diethanolamine and 124 parts of N-methylethanolamine were reacted until the epoxy group disappeared. Next, ethylene glycol monobutyl ether was added to adjust the solid content to obtain a pigment-dispersing resin C-2 containing a tertiary ammonium base having a solid content of 60%.

Production Example 38
To a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin) 1010 parts, bisphenol A 390 parts, Placcel 212 (trade name, polycaprolactone) Diol, Daicel Chemical Industries, Ltd., 240 parts by weight average molecular weight 1,250) and 0.2 parts dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent was about 1090. Next, 200 parts of ethylene glycol monobutyl ether, 122 parts of thiodiglycol, 200 parts of dimethylolpropionic acid and 100 parts of deionized water were added and reacted at 75 ° C. until the epoxy group disappeared. Next, propylene glycol monomethyl ether was added to adjust the solid content to obtain a pigment-dispersing resin C-3 containing a tertiary sulfonium base having a solid content of 60%.

Production Example 39
To a flask equipped with a stirrer, thermometer, dropping funnel and reflux condenser, jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin) 1010 parts, bisphenol A 390 parts, Placcel 212 (trade name, polycaprolactone) Diol, Daicel Chemical Industries, Ltd., 240 parts by weight average molecular weight 1,250) and 0.2 parts dimethylbenzylamine were added and reacted at 130 ° C. until the epoxy equivalent was about 1090. Next, 134 parts of dimethylethanolamine and 150 parts of a 90% strength lactic acid aqueous solution were added and reacted at 90 ° C. until the epoxy group disappeared. Next, propylene glycol monomethyl ether was added to adjust the solid content to obtain a pigment dispersion resin C-4 containing a quaternary ammonium base having a solid content of 60%. The concentration of the quaternary ammonium salt of the pigment dispersing resin C-4 is 0.78 mmol / g.

Production Example 40
To the flask was added 696 parts of tolylene diisocyanate (TDI) and 304 parts of methyl isobutyl ketoxime (MIBK), the temperature was raised to 60 ° C., 520 parts of 2-ethylhexyl alcohol was added dropwise, and the reaction was continued until the NCO value was 110.5. A partially blocked isocyanate A having a resin solid content of 80% was obtained.

Next, 380 parts of this partially blocked isocyanate A was taken, 89 parts of dimethylethanolamine was added dropwise at 70 ° C., and the reaction was carried out until substantially no NCO was obtained. After dilution with 34.75 parts of ethylene glycol monobutyl ether, 90% Neutralized with 100 parts of lactic acid to obtain 80% lactic acid neutralized amino group-containing blocked isocyanate B.
To another flask, 1125 parts of jER828EL (trade name, manufactured by Mitsubishi Chemical Corporation, epoxy resin, epoxy equivalent 188), 456 parts of bisphenol A and 1.1 parts of triphenylphosphonium iodide are added, and epoxy equivalent at 170 ° C. After reacting to 790, it was diluted with 279 parts of MIBK, then added with 760 parts of the above partially blocked isocyanate A, and reacted at 100 ° C. until substantially no NCO was present.

Next, 630 parts of ethylene glycol monobutyl ether was added and cooled to 80 ° C., and 860 parts of 80% lactic acid neutralized amino group-containing blocked isocyanate B was added and reacted until the acid value became 1 mg KOH / g or less, and then propylene glycol monomethyl Ether was added to adjust the solid content to obtain pigment dispersing resin C-5 containing a quaternary ammonium base having a solid content of 60%. The concentration of the quaternary ammonium salt of the pigment dispersing resin C-5 is 0.48 mmol / g.

Production and production example 41 of pigment dispersion paste
8.3 parts of pigment dispersion resin C-1 having a solid content of 60% obtained in Production Example 36 (5 parts of solid content), 14.5 parts of titanium oxide, 7.0 parts of purified clay, 0.3 part of carbon black, 1 part of dioctyltin oxide, 1 part of bismuth hydroxide and 20.3 parts of deionized water were added and dispersed in a ball mill for 20 hours to obtain a pigment dispersion paste PP-1 having a solid content of 55%.

Production Examples 42 to 53
Except for the composition shown in Table 2 below, blending was conducted in the same manner as in Production Example 41 to produce a pigment dispersion paste, and pigment dispersion pastes PP-2 to 13 having a solid content of 55% were produced.

In addition, all the compounding quantities in a table | surface are the values of resin solid content.

Cationic electrodeposition coating production and production example 54
83.8 parts of amino group-containing epoxy resin A-1 obtained in Production Example 34 (67 parts of solid content) and 35 parts of blocked polyisocyanate B-1 obtained in Production Example 35 (28 parts of solid content) were mixed. Further, 13 parts of 10% acetic acid was blended and stirred uniformly, and then dripped in about 15 minutes with vigorous stirring of deionized water to obtain an emulsion having a solid content of 34%.
Next, 294 parts of the emulsion (100 parts of solid content), 52.4 parts of the 55% pigment dispersion paste PP-1 obtained in Production Example 41 (28.8 parts of solid content), and 350 parts of deionized water were added. A cationic electrodeposition paint Y-1 having a solid content of 20% was produced.

Production Examples 55-71
Except for the composition shown in Table 3 below, blending was conducted in the same manner as in Production Example 54 to produce a cationic electrodeposition paint, and cationic electrodeposition paints Y-2 to 18 having a solid content of 20% were produced.

In addition, all the compounding quantities in a table | surface are the values of solid content.

Test plate production Example 1
The test plate Z-1 was produced by the following steps 1-1 to 2-3.

Process 1 (Degreasing-Surface adjustment-Chemical conversion treatment)
Step 1-1: 2.0% by mass of “Fine Cleaner L4460” (manufactured by Nihon Parkerizing Co., Ltd., alkaline degreasing agent) is adjusted to a temperature of 43 ° C., and a cold-rolled steel sheet (70 mm × 150 mm × 0.8 mm) is 120 Degreasing was performed by dipping for 2 seconds.
Step 1-2: Surface adjustment is performed by immersing the steel sheet in a 0.15% aqueous solution of “preparene 4040N” (manufactured by Nihon Parkerizing Co., Ltd., surface conditioner) for 30 seconds, and then using pure water. For 30 seconds.
Step 1-3: The chemical conversion treatment solution X-1 obtained in Production Example 1 was adjusted to a temperature of 43 ° C. and the steel sheet was immersed for 120 seconds to perform chemical conversion treatment.

Process 2 (Washing-electrodeposition coating-baking drying)
Step 2-1: The steel sheet on which the chemical conversion film obtained in Step 1 was formed was immersed in pure water for 30 seconds and washed with water. (Equivalent to the water washing step II described later)
Step 2-2: The cationic electrodeposition paint Y-1 obtained in Production Example 54 was adjusted to a temperature of 28 ° C., and the steel sheet was immersed in a bath of the cationic electrodeposition paint, and 250 V, 180 seconds (30 seconds) Electrodeposition coating was carried out under the conditions of the rising voltage).
Step 2-3: The steel sheet is washed with water by immersing it for 120 seconds once with clean water and once with pure water, and then baked and dried by an electric dryer at 170 ° C. for 20 minutes. As a result, a test plate Z-1 having a multi-layer coating having a dry film thickness of 24 μm was obtained.

Examples 2 to 56, Comparative Examples 1 to 10
Test plates Z-2 to 66 were obtained in the same manner as in Example 1 except that the chemical conversion treatment liquid, the water washing step and / or the cationic electrodeposition coating composition shown in Table 4 below were used. Moreover, since the evaluation test of the appearance unevenness and the anticorrosion property was performed on the obtained test plate as finish, the evaluation results are also shown in Table 4 below. In addition, the detail of the water washing process used by the Example and the comparative example, the ion concentration measuring method, the electrical conductivity measuring method, and the evaluation method of external appearance nonuniformity and anticorrosion property (560 hours, 840 hours) are shown below.

<Washing process>
The water washing step (Step 2-1) used in Examples and Comparative Examples is shown. From the viewpoint of shortening the process, it is preferable that the process is short. From the viewpoint of environment and economy, it is more preferable that the process uses less washing water. In the following water washing steps II to V, part or all of the water washing step is omitted as compared with the conventional water washing step I.
Water-washing step I: After the chemical conversion treatment, a conventional type in which the article to be coated is subjected to 30-second immersion water washing once using clean water and then once to 30-second immersion water washing using pure water. It is a water washing process (two or more immersion water washings), and the process is the longest.
Water washing step II: After the chemical conversion treatment, the object to be coated is subjected to a 30-second immersion water washing once using pure water, which is a water washing step rather than a conventional water washing step (two or more immersion water washings). Is partially omitted.
Water washing step III: After chemical conversion treatment, a process of spraying water for 3 seconds using pure water on the object to be coated, which is a step more than the conventional water washing step (two or more times of immersion type water washing). A part of the process is omitted, and the process is slightly shorter than the one-time immersion water washing in the water washing process II.
Water washing step IV: After the chemical conversion treatment, there is no water washing step, and then air blowing for 10 seconds (room temperature, air pressure on the surface of the object to be coated: 0.2 MPa) to the object to be coated. Short and no waste water from washing water.
Washing process V: After the chemical conversion treatment, there is no washing process, the process is the shortest, and no waste water of washing water is produced.

<Ion concentration>
In the above examples and comparative examples, a test plate immediately before electrodeposition coating was prepared separately, put in a container in a vertical state, covered and left for 1 hour. Next, the test plate was taken out, and the ion concentration of the solution accumulated in the lower part of the container was measured. The ion concentration was measured using an atomic absorption analyzer (trade name: Zeeman atomic absorption photometer, manufactured by HITACHI). In addition, when the quantity required for the measurement of electrical conductivity could not be secured with one test plate, the required quantity was secured using a plurality of test plates.

<Conductivity>
Electrical conductivity (μS / cm) was measured using a sample similar to the above ion concentration. The conductivity was measured using CONACTIVITY METER DS-12 (manufactured by Horiba, Ltd.).

<Appearance unevenness>
The appearance of the obtained test plate was observed, and the appearance unevenness was evaluated as the finish of the multilayer coating. About evaluation, it evaluated by the following references | standards from A (very good) to F (poor). A to D are acceptable levels as finish, and E and F are unacceptable.
A: It has a very uniform appearance.
B: It has a uniform appearance.
C: Although visually recognized as slightly uneven, it has a substantially uniform appearance.
D: Although unevenness is visually recognized, it is a pass level because it is concealed if a top coat is applied on the multilayer coating.
E: Appearance is uneven and slightly poor. Moreover, even if a top coat is applied on the multilayer film, it is not concealed.
F: Appearance is clearly uneven and defective. Moreover, even if a top coat is applied on the multilayer film, it is not concealed.

<Anti-corrosion (560 hours)>
Cross-cut scratches are made on the multilayer coating with a cutter knife so as to reach the base of the test plate, and this is subjected to a salt spray test at 35 ° C. for 560 hours in accordance with JIS Z-2371. The width was measured. About evaluation, it evaluated by the following references | standards from A (very good) to F (poor). A to D are acceptable levels as corrosion resistance (560 hours), and E and F are unacceptable.
A: The maximum width of rust and swelling is 2.0 mm or less (one side) from the cut part, and the corrosion resistance is very good.
B: The maximum width of rust and blisters exceeds 2.0 mm from the cut part, and is 2.5 mm or less (one side), and the corrosion resistance is good.
C: The maximum width of rust and blisters exceeds 2.5 mm from the cut portion, and is 3.0 mm or less (one side), and the corrosion resistance is slightly good.
D: The maximum width of rust and blisters exceeds 3.0 mm from the cut portion, and is 3.5 mm or less (one side), and the corrosion resistance is normal (passed level or higher).
E: The maximum width of rust and blisters exceeds 3.5 mm from the cut part and is 4.0 mm or less (one side), and the corrosion resistance is slightly poor.
F: The maximum width of rust and blistering exceeds 4.0 mm from the cut part (one side), and the corrosion resistance is poor.

<Anti-corrosion (840 hours)>
A cross-cut flaw is made on the multilayer film with a cutter knife so as to reach the substrate of the test plate, and this is subjected to a 35 ° C. salt spray test for 840 hours in accordance with JIS Z-2371. The width was measured. About evaluation, it evaluated by the following references | standards from A (very good) to G (very bad). A to E are acceptable levels as corrosion resistance (840 hours), and F and G are unacceptable.
A: The maximum width of rust and swelling is 2.0 mm or less (one side) from the cut part, and the corrosion resistance is very good.
B: The maximum width of rust and blisters exceeds 2.0 mm from the cut part, and is 2.5 mm or less (one side), and the corrosion resistance is good.
C: The maximum width of rust and blisters exceeds 2.5 mm from the cut portion, and is 3.0 mm or less (one side), and the corrosion resistance is slightly good.
D: The maximum width of rust and blisters exceeds 3.0 mm from the cut portion, and is 3.5 mm or less (one side), and the corrosion resistance is normal (passed level or higher).
E: The maximum width of rust and blisters exceeds 3.5 mm from the cut part and is 4.0 mm or less (one side), and the corrosion resistance is slightly poor.
F: The maximum width of rust and blisters exceeds 4.0 mm from the cut part, and is 5.0 mm or less (one side), and the corrosion resistance is poor.
G: The maximum width of rust and swelling exceeds 5.0 mm from the cut part (one side), and the corrosion resistance is very poor.

Claims

The following processes for forming a chemical conversion treatment film and an electrodeposition coating film on a metal object:
Step 1: a step of immersing a metal coating in a chemical conversion treatment solution to form a chemical conversion treatment film,
Step 2: In a multilayer film forming method including a step of forming an electrodeposition coating film by electrodeposition-coating the metal coating using a cationic electrodeposition coating,
The cationic electrodeposition coating composition is based on the total amount of resin solids, amino group-containing epoxy resin (A) 40 to 88 mass%, blocked polyisocyanate (B) 10 to 50 mass%, pigment dispersion resin (C) A method for forming a multilayer film, comprising 2 to 40% by mass, wherein the quaternary ammonium salt concentration in the cationic electrodeposition coating is 0.03 mmol / g or less per resin solid content in the coating.
The method for forming a multilayer film according to claim 1, wherein in step 2, part or all of the water washing step before electrodeposition coating is omitted.
At least one resin used as the pigment dispersion resin (C) contains at least one selected from a sulfonium base and a tertiary ammonium base as a functional group, and is used as the pigment dispersion resin (C). The method for forming a multilayer film according to claim 1 or 2, wherein the concentration of the quaternary ammonium salt per resin solid content of the total resin is 0.7 mmol / g or less.
4. The electric conductivity of the solution adhering to and / or staying on the metal object during the electrodeposition coating in the step 2 is less than 10,000 μS / cm. The method for forming a multilayer film according to claim 1.
The sodium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution, according to any one of claims 1 to 4. A method for forming a multilayer film.
The potassium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution, according to any one of claims 1 to 5. A method for forming a multilayer film.
The calcium ion concentration of the solution adhering to and / or stagnating on the metal coating object is less than 500 ppm, based on the mass of the solution, according to any one of claims 1 to 6. A method for forming a multilayer film.
The magnesium ion concentration of the solution adhering to and / or stagnating on the metal coating is less than 500 ppm, based on the mass of the solution, according to any one of claims 1 to 7. A method for forming a multilayer film.
The chemical conversion treatment solution is at least one metal compound selected from zirconium, titanium, cobalt, aluminum, vanadium, tungsten, molybdenum, copper, zinc, indium, bismuth, yttrium, iron, nickel, manganese, gallium, silver, and lanthanoid metals. The multilayer film formation according to any one of claims 1 to 8, characterized in that it contains at least one metal compound component (M) consisting of 30 to 20,000 ppm in terms of total metal amount (in terms of mass). Method.
The method for forming a multilayer film according to any one of claims 1 to 9, wherein the chemical conversion treatment solution contains a zirconium compound.
The multilayer coating film formation according to any one of claims 1 to 10, wherein the chemical conversion treatment solution contains 0.01 to 40% by mass of a water-dispersible or water-soluble resin composition (P). Method.
The at least one selected from air blow, rocking, and rotation is performed on the metal object before the electrodeposition coating in the step 2 is performed. A method for forming a multilayer film.
A coated article formed with a multilayer coating using the multilayer coating formation method according to any one of claims 1 to 12.