WO2011021374A1

WO2011021374A1 - Post-treatment solution for self-deposited coating film formed on metal surface, and process for production of metallic material having post-treated self-deposited coating film formed thereon

Info

Publication number: WO2011021374A1
Application number: PCT/JP2010/005051
Authority: WO
Inventors: 高▲桑▼英樹; 中山隆臣; 藤野孝洋
Original assignee: 日本パーカライジング株式会社
Priority date: 2009-08-17
Filing date: 2010-08-12
Publication date: 2011-02-24
Also published as: JP2011038173A; TW201127990A; JP5518398B2

Abstract

Disclosed is a post-treatment technique for a self-deposited coating film that contains tannin as a resin component, which does not contain any environmentally hazardous component such as chromium and can impart high levels of corrosion resistance and adhesion properties to the self-deposited coating film. Specifically disclosed is a post-treatment solution for a self-deposited coating film that is formed on a metal surface and contains tannin as a resin component. The post-treatment solution is characterized by being an aqueous solution comprising at least one metal component selected from the group consisting of lithium, manganese, iron, cobalt, nickel, copper and aluminum and phosphoric acid.

Description

Post-treatment liquid for autodeposition coating on metal surface and method for producing metal material with post-processed autodeposition coating

The present invention is a surface of an iron-based metal material that requires high corrosion resistance and adhesion, such as automobile bodies, automobile parts, steel furniture, and home appliances, and that may be overcoated in accordance with the application. It relates to processing technology. In particular, the present invention aims to form an autodeposition composition containing tannin, an acid and an oxidizing agent on the surface of the metal material for the purpose of forming an autodeposition film having excellent corrosion resistance and adhesion on the surface of the iron-based metal material. This is a technique related to chemical treatment (post-treatment) applied to an uncured autodeposition coating formed on the same surface by bringing it into contact.

Japanese Patent Publication No. 47-17630, Japanese Patent Publication No. 48-14412 are self-deposition compositions that can form a resin film on the metal surface by contacting the metal surface with an acidic composition containing an organic coating resin. Japanese Patent Publication No. 52-21006, Japanese Patent Publication No. 52-35692, Japanese Patent Publication No. 53-15093, Japanese Patent Publication No. 53-16010, Japanese Patent Publication No. 53-44949, Japanese Patent Publication No. 54-13435, Japanese Patent Publication No. Sho 60-58474. JP-A-61-168673 and JP-A-61-246267.

Conventionally known autodeposition compositions are characterized in that by immersing a clean metal surface in the autodeposition composition, an autodeposition coating whose thickness or weight increases with the immersion time can be formed. Furthermore, a part of the metal ions eluted from the metal by the chemical action (etching) of the autodeposition composition on the surface of the metal is taken into the film to form a film. An autodeposited film can be effectively formed on the metal surface without using.

However, since the conventional autodeposition composition coating has insufficient corrosion resistance and adhesion, various means have been developed to further improve the corrosion resistance and adhesion of the autodeposition coating formed on the metal surface. It was done. For example, various methods are known in which a chemical treatment (post-treatment) is performed on an uncured autodeposition coating.

U.S. Pat. Nos. 3,647,567, 4,030,945 and JP-A-61-168673 disclose a chromium compound before drying an uncured autodeposition coating formed on a metal surface. It is disclosed that an autodeposition coating excellent in corrosion resistance can be obtained by contacting with an aqueous solution containing. However, at present, it is not preferable to use a treatment liquid containing chromium whose use is restricted from the viewpoint of environmental problems.

Patent Documents 1 to 3 have proposed a method that does not use chromium. First, in Patent Document 1, before drying an uncured autodeposition coating formed on a metal surface, the water permeability of the dried coating is made non-contact by contacting with an aqueous solution of an alkali metal or ammonium hydroxide. It is taught to permeate and improve the water resistance of the coating. Further, Patent Document 2 discloses a self-deposited coating film in which a metal to be coated is coated with an aqueous coating composition and then baked and coated. It is disclosed to wash with an aqueous solution or an aqueous dispersion mainly containing at least one selected from the group of salts, borofluoride, titanium fluoride, aluminum fluoride and nitrite. Furthermore, Patent Document 3 discloses that an autodeposition coating deposited on a metal substrate is brought into contact with an aqueous solution containing a Group II A or Group II B metal cation and a phosphate anion before curing. It is disclosed that a phosphate compound is generated at the interface of the coating and the corrosion resistance is improved.
JP 60-58474 A JP 52-56142 A Special table 2004-523648

Here, when tannin is selected as the resin component of the autodeposition composition, tannin itself has excellent corrosion resistance. Therefore, the autodeposition coating using tannin as the resin component gives good results in many test items. be able to. However, when the conventional post-treatment agent is used for the autodeposition coating using tannin as the resin component, the present inventors have tested all the test items required by the present inventors, specifically, the salt warm water test, the salt spray It was confirmed that a high level of corrosion resistance and adhesion satisfying all the test items of the test, the combined environmental cycle test and the adhesion test could not be obtained. Accordingly, the present invention provides a post-treatment technique that imparts a high level of corrosion resistance and adhesion to an autodeposition coating using tannin as a resin component, without using harmful components such as chromium. With the goal.

As a result of intensive studies on the means for solving the above problems, the present inventors have found that a post-treatment liquid for self-deposition coating on a metal surface and a self-treatment that does not exist in the prior art as an auto-deposition coating using tannin as a resin component. It came to invent the post-processing method for depositing films.

The present invention (1) is an aqueous solution containing at least one metal component selected from the group consisting of lithium, manganese, iron, cobalt, nickel, copper and aluminum and phosphoric acid. It is a post-treatment liquid for autodeposition coating on the metal surface as a resin component.

In the present invention (2), K = A / B which is the ratio of the total molar concentration A of the metal components to the molar concentration B of the phosphoric acid is represented by the formula (1):
(Formula 2)

And the molar concentration A in the aqueous solution is in the range of 0.1 to 500 mmol / L as the concentration in the aqueous solution.

The present invention (3) is the post-treatment liquid of the invention (1) or (2), wherein the post-treatment liquid for autodeposition coating on the metal surface has a pH of 2 to 6.

In the present invention (4), the post-treatment liquid for autodeposition coating on the metal surface is selected from the group consisting of nitrite, hydroxylamine, hydroxylamine sulfate, hydroxylamine phosphate, hydroxylamine hydrochloride, hydroxylammonium and hydrogen peroxide. Any one of the post-treatment liquids according to any one of the inventions (1) to (3).

The present invention (5) is the post-treatment liquid according to any one of the inventions (1) to (4), wherein the self-deposited film contains at least one selected from the group consisting of cerium, yttrium, aluminum and strontium. is there.

The present invention (6) is the post-treatment liquid of the invention (5), wherein cerium, yttrium, aluminum and strontium are fluoride particles.

In the invention (7), in forming the autodeposition film, at least one crosslinking agent having a phenolic hydroxyl group and / or a crosslinking group capable of thermosetting reaction with a phenol nucleus is used. 1) A post-treatment liquid of any one of (6).

The present invention (8) is the post-treatment liquid according to the invention (7), wherein the crosslinking group capable of thermosetting reaction in the at least one crosslinking agent is an isocyanate group.

The present invention (9) is the post-treatment liquid of the invention (8), wherein the at least one crosslinking agent is a polyfunctional blocked isocyanate blocked with a blocking agent.

In the invention (10), the at least one crosslinking agent is at least one selected from block isocyanates having at least one molecule of bisphenol A structure and / or self-emulsifying type blocked isocyanates using polyether polyol. This is a post-treatment liquid of the invention (9).

In the present invention (11), an uncured self-deposited film is formed on a metal surface by bringing a self-deposited composition containing tannin as a resin component into contact with a metal material whose surface has been cleaned in advance by degreasing and washing with water. A metal material comprising: a precipitation coating step; a contact step of bringing the post-treatment liquid according to any one of the inventions (1) to (10) into contact with the uncured self-deposition coating; and a baking step This is a surface treatment method.

BEST MODE FOR CARRYING OUT THE INVENTION

<Post-treatment liquid for self-deposited film>
The post-treatment liquid for self-deposition of a metal surface according to the present invention is for an auto-deposition film containing tannin as a resin component, and is at least one selected from the group consisting of lithium, manganese, iron, cobalt, nickel, copper and aluminum It is the aqueous solution containing the metal component and phosphoric acid. Hereinafter, each component, composition, and liquid property in the aqueous solution will be described.

(component)
<Metal component>
Lithium, manganese, iron, cobalt, nickel, copper, and aluminum used in the present invention are metal parts in forming a phosphate compound that provides excellent corrosion resistance and adhesion to an autodeposition coating containing tannin as a resin component. It becomes. Here, when an aqueous solution containing these metal components and phosphoric acid is applied to an autodeposition coating containing tannin as a resin component, the interface between the metal surface and the autodeposition coating is different from the case of using a post-treatment agent in the prior art. The phosphate compound is not unevenly distributed, but is uniformly dispersed and deposited in the autodeposition coating. For this reason, since the phosphate compound which not only improves the corrosion resistance and adhesion at the interface between the metal surface and the self-deposited coating but also has an effect as a rust preventive pigment is uniformly dispersed in the coating, Corrosion resistance can be remarkably improved over the entire coating. Preferred metal components are manganese, cobalt and nickel.

Here, the supply source of the metal component is not particularly limited, and for example, oxides, hydroxides, fluorides, complex fluorides, chlorides, nitrates, oxynitrates, sulfates, oxysulfates of these metal elements , Carbonates, oxycarbonates, phosphates, oxyphosphates, oxalates, oxyoxalates, and organometallic compounds can be used, and two or more can be used in combination.

<Phosphoric acid component>
The phosphoric acid used in the present invention becomes an anion moiety when forming the phosphate compound. Moreover, the supply source of phosphoric acid is not specifically limited, For example, orthophosphoric acid, condensed phosphoric acid, etc. can be used and 2 or more types can be used together.

<Accelerator>
It is preferable to add an accelerator for producing a phosphate compound to the post-treatment liquid for autodeposition coating used in the present invention. The accelerator has an effect of increasing the production amount of the phosphate compound by accelerating the etching reaction on the metal surface on which the uncured autodeposited film has been deposited. Examples of the accelerator include nitrite, hydroxylamine, hydroxylamine sulfate, hydroxylamine phosphate, hydroxylamine hydrochloride, hydroxylammonium, hydrogen peroxide, etc. Among them, nitrite and hydroxylamine are preferable.

(composition)
<Concentration ratio of metal component and phosphoric acid>
K = A / B, which is the ratio of the total molar concentration A of metal components to the molar concentration B of phosphoric acid in the treatment liquid of the present invention, is preferably in the range of formula (1), and in the range of formula (2). More preferably it is. When K is smaller than 0.001, since the ratio of the metal component is small, it is not possible to obtain a phosphate compound sufficient to obtain corrosion resistance and adhesion. On the other hand, when K is larger than 0.5, an excessive metal component may adversely affect the appearance of the autodeposition coating, resulting in appearance defects such as coating cracks and pinholes. The metal component in the post-treatment liquid for autodeposition coating was measured using high frequency inductively coupled plasma optical emission spectrometry (ICP) and represented by the total molar concentration (mol / L) as each metal element in the treatment liquid. Is done. In addition, phosphoric acid in the post-treatment liquid for autodeposition coating is measured using ion chromatography (IC) and is expressed as a molar concentration (mol / L) as PO4 in the treatment liquid.
(Formula 3)

(Formula 4)

<Concentration of metal component>
The concentration of the metal component in the treatment liquid of the present invention is preferably 0.1 to 500 mmol / L, more preferably 1 to 100 mmol / L. When the concentration of the metal component is less than 0.1 mmol / L, formation of a phosphate compound sufficient to obtain corrosion resistance and adhesion cannot be obtained. On the other hand, if it is higher than 500 mmol / L, the amount of the phosphate compound formed becomes too large, which may cause an abnormality in the appearance of the self-deposited film, and is also disadvantageous economically. Further preferable concentrations of the metal component in the treatment liquid of the present invention are 20 mmol / L or more for manganese, 5 mmol / L or more for cobalt, 30 mmol / L or more for nickel, and 1 mmol / L or more for lithium, iron, copper, and aluminum.

<Concentration of accelerator>
The concentration of the accelerator when it is added is preferably 1 to 1000 mmol / L, more preferably 10 to 300 mmol / L. When the concentration of the accelerator is less than 1 mmol / L, it is not possible to obtain a sufficient promoting effect for obtaining corrosion resistance and adhesion. On the other hand, when it is higher than 1000 mmol / L, as the metal etching reaction is promoted, the amount of the phosphate compound formed becomes excessive, and the appearance of the autodeposition coating may be abnormal.

(liquid)
The post-treatment liquid for autodeposition coating used in the present invention is preferably adjusted and maintained within the range of pH 2-6, more preferably pH 3-5. When the pH is less than 2, the etching reaction of the metal becomes excessive, and abnormalities such as cracking of the film and pinholes occur in the appearance of the film. On the other hand, when the pH is higher than 6, a phosphate compound may be formed and precipitated in the post-treatment liquid for the autodeposition coating depending on the kind of the metal component, and the effect is lost.

In addition, when it is necessary to adjust the pH within a preferable range, the drug used is not particularly limited. For example, acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, organic acids; lithium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, alkali metal salts, ammonia, Examples include alkalis such as ammonium salts and amines.

"how to use"
(Metal materials to be used)
The post-treatment liquid for autodeposition coating of the present invention can be applied to metal materials such as iron-based metal materials and galvanized steel sheets. However, the most suitable metal material is an iron-based metal material. The iron-based metal material as used herein refers to steel sheets such as cold-rolled steel sheets and hot-rolled steel sheets, and iron-based materials such as cast iron and sintered materials.

(Self-deposited film to be used)
The autodeposition coating that is the target of the post-treatment agent of the present invention is a coating that contains at least tannin as a resin component. This autodeposition coating is formed using the autodeposition composition described below.

<Autodeposition composition>
The autodeposition composition is characterized in that an autodeposition coating whose thickness or weight increases with the immersion time can be formed by immersing a clean metal surface in the composition. Furthermore, a part of the metal ions eluted from the metal by the chemical action (etching) of the autodeposition composition on the metal surface is taken into the film, and the film is formed. There is a feature that an autodeposition coating can be effectively formed on the surface of the metal without using a metal.

Here, a suitable autodeposition composition contains a tannin component as a resin and a component having a chemical action (etching). A more preferable autodeposition composition is obtained by mixing a tannin component as a resin, an acid, an oxidizing agent, and a compound capable of supplying ferric ions as required, and further adding water as necessary. is there. Hereinafter, each component will be described in detail.

<Tannin>
As described above, the resin component of the autodeposition composition to which the post-treatment liquid according to the present invention is applied contains at least tannin. When the post-treatment liquid for autodeposition coating of the present invention was used for an autodeposition coating in which tannin is a resin component, the anticorrosion property of the phosphate compound was imparted to the coating, and the corrosion resistance was significantly improved. It has become possible to obtain a high level of corrosion resistance and adhesion satisfying all the test items of the salt warm water test, the salt spray test, the combined environmental cycle test, and the adhesion test required by the inventors. Here, the tannin used is not particularly limited. , Spun, hemlock, mangrove, oak bark, condensed tannins such as alabum, Gambia, tea and persimmon, and synthetic tannins as disclosed in JP-A 61-4775. Among them, preferred tannins are hydrolyzed tannins, and more preferred are pentaploids and gallics. Here, the content of tannin is preferably 10 to 90%, more preferably 20 to 50%, based on the total mass (dry) of the autodeposition composition.

<Crosslinking agent>
Further, as a component of the autodeposition composition to which the post-treatment liquid according to the present invention is applied, at least one crosslinking agent having a phenolic hydroxyl group and / or a crosslinking group capable of thermosetting reaction with a phenol nucleus is included. Is preferred. The term “phenolic hydroxyl group” as used herein refers to the hydroxyl group of phenols, and the term “phenol nucleus” refers to a carbon in the ortho or para position relative to the hydroxyl group of phenol. As the crosslinking group of the crosslinking agent, a methylol group, a carboxyl group, a glycidyl group, a secondary alcohol group in which a glycidyl group is opened, an isocyanate group, or the like can be used, and among them, an isocyanate group is preferable.

Here, a more preferable crosslinking agent is a polyfunctional blocked isocyanate obtained by adding at least 2 mol of polyisocyanate in which one isocyanate group is blocked with a blocking agent to 1 mol of polyol. The isocyanate group is optimal as a crosslinking agent because it can be inhibited from reaction with water by blocking with a blocking agent, and the blocking agent is dissociated by applying heat to cause a crosslinking reaction. Hereinafter, the details of the preferable crosslinking agent will be described.

-Polyol First, as the polyol, polyether glycol such as polypropylene glycol, polyethylene glycol, polytetramethylene glycol, a copolymer of polyethylene glycol and polypropylene glycol, polyethylene adipate, polydiethylene adipate, polypropylene adipate, Examples thereof include polyester polyols such as polytetramethylene adipate and poly-ε-caprolactone, polycarbonate polyols, acrylic polyols, epoxy polyols, trimethylolpropane, bisphenol A, bisphenol F, and bisphenol AD.

Among these, a preferred first polyol is a polyether polyol. Although the detailed mechanism that supports the self-emulsifying type blocked isocyanate using such a polyether polyol is not known at this stage, by using the self-emulsifying type blocked isocyanate using the polyether polyol as the polyol, The deposition rate of the autodeposition coating can be significantly improved. Here, the self-emulsifying type blocked isocyanate means that the polymer molecule itself has an affinity for water by adding an anionic, cationic or nonionic hydrophilic group to the blocked isocyanate polymer molecule. What can be emulsified and dispersed is shown. Of the polyether polyols, polyethylene glycol is particularly suitable for the balance between its water solubility and the deposition rate of the autodeposition coating.

Among them, the preferred second polyol is an epoxy polyol or bisphenol A having at least one bisphenol A structure in the molecular structure. Here, “having at least one molecule of bisphenol A structure” means a polymer such as the above-described epoxy polyol, a polymer partially including a repeating unit of bisphenol A, or a homopolymer of bisphenol A. Or bisphenol A itself. Bisphenol A has a benzene ring in the basic skeleton, and since the two benzene rings are connected by a methylene chain with two methyl groups, the resin itself has robustness (rigidity) and high chemical resistance. It is a structure having both (HO—C ₆ H ₄ —C (CH ₃ ) ₂ —C ₆ H ₄ —OH). Therefore, by using a polyol having a bisphenol A structure in the polyfunctional blocked isocyanate of the present invention, the corrosion resistance is drastically improved.

-Polyisocyanate Next, a well-known thing can be used as said polyisocyanate. For example, 1,4-tetramethylene diisocyanate, ethyl (2,6-diisocyanate) hexanoate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2,2,4- or 2,4,4-trimethyl Of aliphatic diisocyanates such as hexamethylene diisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 2-isocyanatoethyl (2,6-diisocyanate) hexanoate A diisocyanate having a cyclic structure such as aliphatic triisocyanate and isophorone diisocyanate, m- or p-phenylene diisocyanate, toluene-2,4- or 2,6-diisocyanate, diphenylmethane-4, 'Diisocyanate, naphthalene-1,5-diisocyanate, diphenyl-4,4' diisocyanate, 4,4'-diisocyanate-3,3'-dimethyldiphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate, diphenyl ether Aromatic diisocyanates such as -4,4'-diisocyanate can be used. Among them, preferred polyisocyanates are 1,6-hexamethylene diisocyanate from the viewpoint of the flexibility of the resulting film, and toluene-2,4- or 2,6-diisocyanate from the viewpoint of the reactivity of the isocyanate group.

Blocking agent Next, known blocking agents for the isocyanate group can be used. For example, alcohol such as methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, tert-butyl alcohol, phenol, methylphenol, chlorophenol, p-iso-butylphenol, p -Phenols such as tert-butylphenol, p-iso-amylphenol, p-octylphenol and p-nonylphenol; active methylene compounds such as malonic acid dimethyl ester, malonic acid diethyl ester, acetylacetone, methyl acetoacetate and ethyl acetoacetate; Formaldoxime, acetoaldoxime, acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, acetophenone oxime, benzophenone oxime Oximes such as 2-butanone oxime, .epsilon.-caprolactam, .delta.-valerolactam, lactams such as γ- butyrolactam and thiosulfate salts.

<Acid / Oxidizing agent>
As the acid and / or oxidizing agent, for example, at least one selected from zircon hydrofluoric acid, titanium hydrofluoric acid, silicohydrofluoric acid, borohydrofluoric acid, hydrofluoric acid, phosphoric acid, nitric acid and the like can be used. Hydrofluoric acid is preferred.

<Compound capable of supplying ferric ion>
The compound capable of supplying ferric ions is not particularly limited as long as it is stable in the autodeposition composition, and examples thereof include ferric fluoride, ferric nitrate, and ferrous phosphate. Ferric fluoride is preferred.

<Anti-rust pigment>
The autodeposition composition that can be used in the present invention may contain a rust preventive pigment selected from the group consisting of cerium, yttrium, aluminum, and strontium. Here, the cerium, yttrium, aluminum, and strontium are preferably fluoride particles. Hereinafter, the fluoride particles will be described in detail.

Since the fluoride particles have low solubility in an aqueous hydrofluoric acid solution, the supplied fluoride exists almost as solid particles in the surface treatment liquid of the present invention, and when the organic coating is deposited by an autodeposition reaction. It is incorporated into the film. Corrosion resistance of the autodeposition coating is improved by the incorporated fluoride particles. At the present time, the effect of the fluoride particles is not clear, but the presence of fluoride particles in the coating slows the rate at which the corrosion promoting components that have entered the coating reach the metal interface, and baking. This is considered to have an effect of promoting the crosslinking reaction between the resin component in the autodeposition coating film and the crosslinking agent.

As at least one selected from the group consisting of cerium fluoride, yttrium fluoride, aluminum fluoride, and strontium fluoride, a commercially available salt may be used, or a soluble metal salt such as cerium nitrate and hydrofluoric acid You may use the particle | grains which are the deposits precipitated by making it react. Moreover, the preferable average particle diameter of at least 1 sort (s) chosen from the group which consists of cerium fluoride, yttrium fluoride, aluminum fluoride, and strontium fluoride is 50 micrometers or less, More preferably, it is 10 micrometers or less. Moreover, the preferable minimum of the average particle diameter of fluoride particle | grains is 0.1 micrometer from the effect | action which delays the moving speed | rate of the corrosion promotion component by it.

(process)
In the post-treatment method for metal autodeposition coating of the present invention, a degreasing step in which the surface is washed in advance by degreasing and water washing treatment, an iron-based metal material after the degreasing step is brought into contact with the autodeposition composition, and the surface of the metal is not deposited An uncured self-deposited film forming step for forming a cured self-deposited film; a post-treatment liquid contacting step for bringing the uncured self-deposited film into contact with the post-treatment liquid for self-deposited film; and a baking step. Hereinafter, each process will be described.

<Degreasing process>
For the degreasing treatment, conventionally used solvent degreasing, alkali degreasing and the like can be used, and the construction method is also poured, and there are no restrictions such as spraying, dipping and electrolysis. Moreover, there is no restriction | limiting also about the water washing process performed after a degreasing process (and also after an autodeposition coating process), It can select from pouring, spraying, immersion, etc. The quality of water used for washing is not particularly limited, but ion-exchanged water is a preferred choice in consideration of bringing in small components into the autodeposition coating treatment bath and remaining in the coating.

<Uncured autodeposition coating formation process>
There is no particular limitation on the method of treating the metal surface using the autodeposition composition that can be used in the present invention, and a general application method of a surface treatment agent such as a dipping method, a spray method, or a roll coating method is adopted. A dipping method is preferred. The treatment temperature and treatment time are not particularly limited, but in the case of immersion treatment, it is generally appropriate to immerse in the composition at room temperature, for example, 18 to 25 ° C. for 30 to 600 seconds, preferably 90 to 300 seconds. is there. The amount of the autodeposition composition applied to the metal is not particularly limited, but the film thickness after baking is preferably 5 to 40 μm.

Here, after the autodeposition composition is applied to the metal, the post-treatment of the present invention may be performed immediately. However, the post-treatment of the present invention is preferably performed after washing with water. This water washing is usually performed by immersing in normal temperature water for 10 to 180 seconds, preferably 20 to 120 seconds.

<Post-treatment liquid contact process>
The treatment time (for example, immersion time) in the post-treatment for the self-deposited film is not particularly limited, but the preferred treatment time for obtaining the effect of the present invention is 10 seconds to 5 minutes, more preferably 30 seconds to 2 minutes. is there. Usually, after the treatment is completed (for example, after the completion of immersion), baking is performed immediately, but washing may be performed before the baking process.

<Baking process>
A preferable baking temperature in the baking step is 170 to 220 ° C, more preferably 180 to 200 ° C. A preferable baking time in the baking step is 10 to 60 minutes, more preferably 20 to 40 minutes.

<Application>
Applications of the metal material having the post-processed autodeposition coating according to the present invention are automobile bodies, automobile parts, steel furniture, home appliances, etc. It can be used in combination with other top coating such as solvent coating.

Hereinafter, examples will be given together with comparative examples, and the post-treatment liquid for autodeposition coating on a metal surface and the post-treatment method for autodeposition coating of the present invention will be specifically described. In addition, the to-be-processed material used in the Example, a degreasing agent, and a coating material are arbitrarily selected from commercially available materials, and for the post-treatment liquid for the autodeposition coating on the metal surface of the present invention and for the autodeposition coating It does not limit the actual use of the post-processing method.

(Test plate)
The abbreviations and breakdown of the test plates used in the examples and comparative examples are shown below.
・ CRS (Cold rolled steel sheet: JIS-G-3141)

Examples 1 to 23 and Comparative Examples 1 to 3
A commercially available alkaline degreasing agent, Fine Cleaner L4460 (Nippon Parkerizing Co., Ltd.) was diluted with water to 2% by mass and humidified to 40 ° C., and sprayed on a test plate with a spray device to perform degreasing treatment. The surface of the test plate after the degreasing treatment was washed with ion-exchanged water using a spray device. The test plate whose surface was degreased and washed was prepared by using commercially available tannin (trade name: Tannic acid AL: Fuji Chemical Industry Co., Ltd.) and a commercially available water-soluble blocked isocyanate (trade name: Elastron H38: Daiichi Kogyo Seiyaku Co., Ltd.). ), And a commercially available polyethylene glycol self-emulsifying type blocked isocyanate (trade name Takenate WB-920: manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), hydrofluoric acid (reagent), hydrogen peroxide ( Reagent), cerium fluoride (reagent), and ferric fluoride (prepared by mixing iron powder (reagent) and hydrofluoric acid (reagent)), and prepared in the autodeposition coating treatment bath shown in Table 1 After dipping for 3 minutes and washing with ion-exchanged water using a spray device, it is immersed in the post-treatment bath for autodeposition coating having the composition shown in Table 3 at the treatment temperature shown in Table 3 for the treatment time shown in Table 3. Then baked 180 ° C. × 20 min. The coated metal materials obtained in the respective examples and comparative examples were evaluated according to the methods described later.

Comparative example 4
A commercially available alkaline degreasing agent, Fine Cleaner L4460 (manufactured by Nihon Parkerizing Co., Ltd.) was diluted to 2% by mass with water and moisturized at 40 ° C., and sprayed on a test plate with a spray device for degreasing treatment. The surface of the test plate after the degreasing treatment was washed with ion-exchanged water using a spray device. The test plate from which the surface was degreased was washed with commercially available tannin (trade name Tannic Acid AL: manufactured by Fuji Chemical Industry Co., Ltd.) and a commercially available water-soluble blocked isocyanate (trade name Elastron H38: Daiichi Kogyo Seiyaku Co., Ltd.). And a commercially available polyethylene glycol self-emulsifying type blocked isocyanate (trade name Takenate WB-920: manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), hydrofluoric acid (reagent), hydrogen peroxide solution (Reagent), cerium fluoride (reagent), and ferric fluoride (prepared by mixing iron powder (reagent) and hydrofluoric acid (reagent)), and the autodeposition coating treatment bath shown in Table 1 After immersing for 3 minutes and washing with ion exchange water using a spray device, baking was performed at 180 ° C. for 20 minutes without being immersed in the post-treatment bath for autodeposition coating. The coated metal material obtained in this comparative example was evaluated according to the method described later.

Examples 24 to 26 and Comparative Examples 5 and 6
A commercially available alkaline degreasing agent, Fine Cleaner L4460 (manufactured by Nihon Parkerizing Co., Ltd.) was diluted to 2% by mass with water and moisturized at 40 ° C., and sprayed on a test plate with a spray device for degreasing treatment. The surface of the test plate after the degreasing treatment was washed with ion-exchanged water using a spray device. The test plate whose surface was degreased and washed was prepared by using commercially available tannin (trade name: Tannic acid AL: manufactured by Fuji Chemical Industry Co., Ltd.) and a commercially available water-soluble blocked isocyanate (trade name: Elastron H38: Daiichi Kogyo Seiyaku Co., Ltd.). And a commercially available polyethylene glycol self-emulsifying type blocked isocyanate (trade name Takenate WB-920: manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), hydrofluoric acid (reagent), hydrogen peroxide solution (Reagent) and ferric fluoride (prepared by mixing iron powder (reagent) and hydrofluoric acid (reagent)) for 3 minutes in an autodeposition coating treatment bath shown in Table 2 and sprayed After washing with ion-exchanged water using an apparatus, it was immersed in a post-treatment bath for autodeposition coating having the composition shown in Table 3 at the treatment temperature shown in Table 3, and then treated at 180 ° C. for 20 minutes. Baking was performed. Furthermore, a commercially available aminoalkyd-based intermediate coating (trade name Amirac TP-37 Gray: manufactured by Kansai Paint Co., Ltd., film thickness 35 μm, spray coating, baked at 140 ° C. for 20 minutes), and a commercially available aminoalkyd-based topcoat ( Product name Amirac TM-13 white: manufactured by Kansai Paint Co., Ltd., film thickness 35 μm, spray coating, baking at 140 ° C. for 20 minutes). The coated metal materials obtained in the respective examples and comparative examples were evaluated according to the methods described later.

(Evaluation of film thickness of autodeposition coating metal materials)
The film thickness of the test plates in Examples and Comparative Examples was measured using an electromagnetic film thickness meter (Fisherscope MMS: manufactured by FISCHER).

(Performance evaluation of self-deposited coating materials)
The performance evaluation of Examples and Comparative Examples was performed. Evaluation items and abbreviations are shown below. The self-deposited film after baking is referred to as a self-deposited film, and the coating film that has been subjected to baking after top coating is referred to as a 3 caots coating film.
(1) SDT: salt warm water test (self-deposited coating)
(2) SST: Salt spray test (self-deposited coating)
(3) DuPont: DuPont impact test (self-deposited coating)
(4) CCT: Combined environmental cycle test (3caots coating)
(5) 1STADH: Primary adhesion (3coats coating film)
(6) 2ndADH: Water resistant secondary adhesion (3coats coating film)

・ SDT
The self-deposited coated film with the cross cut cut by a sharp cutter was immersed in a 5 mass% NaCl aqueous solution heated to 50 ° C for 240 hours. After completion of the immersion, the crosscut portion washed with tap water and dried at room temperature was peeled off with an adhesive tape, the maximum peel width on both sides of the coating film was measured, and evaluated according to the following criteria.

A: The maximum swollen width on both sides is less than 2.0 mm B: The maximum swollen width on both sides is 2.0 mm or more and less than 4.0 mm Δ: The maximum swollen width on both sides is 4.0 mm or more and less than 6.0 mm ×: The maximum swollen width on both sides is 6. 0mm or more

・ SST
5 mass% salt water was sprayed for 2000 hours (according to JIS-Z-2371) onto a self-deposited coated film having a cross-cut with a sharp cutter. After spraying, the maximum blister width on both sides from the crosscut was measured and evaluated according to the following criteria.

A: The maximum swollen width on both sides is less than 4.0 mm. ○: The maximum swollen width on both sides is 4.0 mm or more and less than 6.0 mm. Δ: The maximum swollen width on both sides is 4.0 mm or more and less than 8.0 mm. 0mm or more

-DuPont A 1 kg vertical weight with a diameter of 1/2 inch was dropped from a height of 50 cm onto the self-deposited coating film plate, and then the impact part was peeled off with an adhesive tape, and evaluated according to the following criteria.

OK: No film peeling NG: Film peeling

・ CCT
A 3caots coated plate with a cross-cut with a sharp cutter is placed in a combined cycle tester, and “salt water spray (5 mass% NaCl aqueous solution, 35 ° C., 17 hours) → dry (70 ° C., 3 hours) → soaked with salt water (5 A cycle of “mass% NaCl aqueous solution, 50 ° C., 2 hours) → natural drying (25 ° C., 2 hours)” was performed 60 cycles. The maximum swollen width on both sides from the cross cut after 60 cycles was measured and evaluated according to the following criteria.

A: The maximum swollen width on both sides is less than 4.0 mm. A: The maximum swollen width on both sides is 4.0 mm or more and less than 6.0 mm. Δ: The maximum swollen width on both sides is 6.0 mm or more and less than 10.0 mm. 0mm or more

・ 1stADH
Cut 100 grids at 2mm intervals with a sharp cutter on the 3coats coating. The grid area was peeled off with adhesive tape, and the number of remaining grids was counted.

・ 2ndADH
The 3coats coated plate was immersed in deionized water at 40 ° C. for 240 hours. After immersion, 100 grids with 2 mm intervals were cut with a sharp cutter. The grid area was peeled off with adhesive tape, and the number of remaining grids was counted.

Table 4 shows the evaluation results of the self-deposited films obtained in Examples 1 to 26 and Comparative Examples 1 to 6.

Examples 1 to 16 have extremely excellent corrosion resistance because they are all evaluated as ◎ in the SDT and SST test results. Furthermore, all the DuPont test results are OK, and it also has good adhesion. On the other hand, compared to Examples 1 to 16, Example 17 has a K = A / B value as low as 0.0005, Example 18 has a K = A / B value as high as 5.0, and Example 19 does not contain an accelerator. Although the SDT and SST test results in were inferior to those of Examples 1 to 16, the evaluation was good. In addition, a DuPont test result is OK and has favorable adhesiveness.

Compared to Examples 1 to 16, the results of the SDT and SST tests in Example 20 where the nickel concentration was as low as 0.1 mmol, Example 21 where the cobalt concentration was as low as 0.4 mmol, and Example 22 where the manganese concentration was as low as 0.2 mmol were as in Example Although it is inferior to 1 to 5, the SDT evaluation is ○, and the SST evaluation is Δ. In addition, a DuPont test result is OK and has favorable adhesiveness.

In Example 23, which has a higher pH than Examples 1-16, precipitates were generated in the uncured autodeposition coating treatment solution, and the results of the SDT and SST tests were higher than those of Examples 1-16. The evaluation of the inferior one is ○. In addition, a DuPont test result is OK and has favorable adhesiveness.

On the other hand, compared with Examples 1 to 23, SDT, SST, and Dupont of Comparative Example 1 containing no metal component and phosphoric acid, Comparative Example 2 containing no phosphoric acid, and Comparative Example 3 containing no metal component described in the present invention The test results are inferior to those of Examples 1-23.

Also, the SDT and SST test results in Comparative Example 4 where the post-treatment for the self-deposited film was not performed are inferior to those in Examples 1 to 23.

Examples 24 to 26 are evaluated as ◎ in the CCT test results, have extremely excellent corrosion resistance, and also have excellent adhesion.

On the other hand, the CCT test results in Comparative Examples 5 and 6 not containing the metal component described in the present invention are inferior to those in Examples 24-26.

From the above, the effects of the present invention are clear.

Claims

In an aqueous solution containing at least one metal component selected from the group consisting of lithium, manganese, iron, cobalt, nickel, copper and aluminum and phosphoric acid, the metal surface containing tannin as a resin component Post-treatment liquid for autodeposition coating.
K = A / B, which is the ratio of the total molar concentration A of the metal components to the molar concentration B of the phosphoric acid, is represented by the formula (1):
(Formula 1)

The post-treatment liquid according to claim 1, wherein the molar concentration A is in the range of 0.1 to 500 mmol / L as the concentration in the aqueous solution.
The post-treatment liquid according to claim 1 or 2, wherein the post-treatment liquid for autodeposition coating on the metal surface has a pH of 2 to 6.
The post-treatment liquid for autodeposition coating on the metal surface contains at least one selected from the group consisting of nitrite, hydroxylamine, hydroxylamine sulfate, hydroxylamine phosphate, hydroxylamine hydrochloride, hydroxylammonium and hydrogen peroxide. The post-treatment liquid according to any one of claims 1 to 3.
The post-treatment liquid according to any one of claims 1 to 4, wherein the self-deposited film contains at least one selected from the group consisting of cerium, yttrium, aluminum, and strontium.
The post-treatment liquid according to claim 5, wherein cerium, yttrium, aluminum, and strontium are fluoride particles.
The at least one crosslinking agent having a crosslinking group capable of thermosetting reaction with a phenolic hydroxyl group and / or a phenol nucleus is used in forming the autodeposition coating. Post-treatment liquid as described.
The post-treatment liquid according to claim 7, wherein the crosslinking group capable of thermosetting reaction in the at least one crosslinking agent is an isocyanate group.
The post-treatment liquid according to claim 8, wherein the at least one crosslinking agent is a polyfunctional blocked isocyanate blocked with a blocking agent.
The at least one crosslinking agent is at least one selected from blocked isocyanates having at least one molecule of bisphenol A structure and / or self-emulsifying blocked isocyanates using polyether polyols. After-treatment liquid.
An uncured self-deposited coating step in which a self-deposited composition containing tannin as a resin component is brought into contact with a metal material whose surface has been cleaned in advance by degreasing and rinsing, thereby forming an uncured self-deposited coating on the metal surface; A surface treatment method for a metal material, comprising a contact step of bringing the post-treatment liquid according to any one of claims 1 to 10 into contact with a cured autodeposition coating, and a baking step.