CN110869534A

CN110869534A - Chemical conversion treatment agent, pretreatment method for coating, and metal member

Info

Publication number: CN110869534A
Application number: CN201880045512.6A
Authority: CN
Inventors: 岸将人; 上野峻之
Original assignee: Nippon Paint Surf Chemicals Co Ltd
Current assignee: Nippon Paint Surf Chemicals Co Ltd
Priority date: 2017-07-13
Filing date: 2018-07-12
Publication date: 2020-03-06
Also published as: US20200165741A1; WO2019013282A1; JP2019019356A

Abstract

The invention provides a chemical conversion treatment agent which has little burden on the environment and can ensure good corrosion resistance after coating regardless of the treatment object. A chemical conversion treatment agent comprising at least one (A) selected from the group consisting of zirconium, titanium and hafnium, at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof and a polymer thereof, fluorine (C), and a cationic polyurethane resin (D). (A) The content of (b) is 20 to 10000 ppm by mass in terms of metal conversion, and the pH of the chemical conversion treatment agent is preferably 1.5 to 6.5.

Description

Chemical conversion treatment agent, pretreatment method for coating, and metal member

Technical Field

The invention relates to a chemical conversion treatment agent, a pretreatment method before coating and a metal member.

Background

When the surface of a metal material is subjected to cationic electrodeposition coating, powder coating, or the like, chemical conversion treatment is generally performed to improve properties such as corrosion resistance and coating film adhesion. In recent years, the harmfulness of chromium has been pointed out in chromate treatment that has been used in chemical conversion treatment from the viewpoint of further improving the adhesion and corrosion resistance of the coating film, and it has been required to develop a chemical conversion treatment agent containing no chromium. As such chemical treatment, treatment using zinc phosphate is widely performed.

However, since the zinc phosphate-based treating agent has a high concentration of metal ions and acid and is very reactive, it is not economical and has poor workability in wastewater treatment. Further, with the metal surface treatment using a zinc phosphate-based treating agent, water-insoluble salts are generated and precipitated as precipitates. Such a precipitate is generally called sludge (slurry), and there is a problem that such sludge is removed and discarded, resulting in a cost. Further, since phosphate ions may cause environmental load due to eutrophication, it is preferable that the phosphate ions are not used because they require labor for waste liquid treatment. Further, when a metal surface treatment is performed using a zinc phosphate-based treating agent, surface conditioning is required, which also has a problem of lengthening the process.

As a metal surface treatment agent other than such a zinc phosphate-based treatment agent or chromate conversion treatment agent, a metal surface treatment agent composed of a zirconium compound is known. Such a metal surface treatment agent composed of a zirconium compound has excellent properties compared with the zinc phosphate-based chemical conversion treatment agent described above in terms of suppressing the generation of sludge.

However, a chemical film obtained by using a metal surface treatment agent composed of a zirconium compound has poor adhesion particularly to a coating film obtained by cationic electrodeposition coating, and is generally rarely used as a pretreatment step of cationic electrodeposition coating. In the metal surface treatment agent composed of the zirconium compound, the adhesion is improved and the corrosion resistance is improved by using a component such as phosphate ions in combination. However, in the case of using phosphate ions in combination, there is a problem of eutrophication as described above. In addition, when an iron-based substrate is treated with such a metal surface treatment agent, there is a problem that sufficient coating film adhesion and corrosion resistance after coating cannot be obtained.

Non-chromate metal surface treatment agents composed of a zirconium compound and an amino group-containing silane coupling agent are also known. However, such a non-chromate metal surface treatment agent is a coating type treatment agent for so-called use in the field of coil coating, and surface treatment using such a non-chromate metal surface treatment agent cannot be washed with water after treatment, and is not suitable for a treated object having a complicated shape.

Further, in some cases, it is necessary to perform surface treatment of all metals by one treatment on articles made of various metal materials such as automobile bodies and parts, including iron, zinc, and aluminum, and in such a case, it is also desired to develop a pretreatment method for coating which can be performed without problems. On the other hand, in coating other than cationic electrodeposition coating using powder coating, solvent coating, water-based coating, or the like, it is also desired to develop a pretreatment method capable of performing chemical conversion treatment without causing the above-described problems.

In order to solve the above-described problems, a pretreatment method for coating in which a treatment object is treated with a chemical conversion agent containing at least one selected from the group consisting of zirconium, titanium and hafnium, fluorine, and at least one selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof and a polymer thereof to form a chemical conversion coating film is known (for example, see patent document 1 described later).

According to the pretreatment method for coating, the coating method is not limited, and the same adhesion and corrosion resistance after coating as those obtained when a zinc phosphate chemical conversion treatment agent is used can be obtained. However, depending on the object to be treated and the application thereof, the obtained post-coating corrosion resistance is not sufficient.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-218070

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a chemical conversion treating agent which has a small burden on the environment and can ensure good corrosion resistance after coating regardless of the treatment target.

Means for solving the problems

The invention relates to a chemical conversion treatment agent, which comprises: at least one (A) selected from the group consisting of zirconium, titanium and hafnium; at least one (B) selected from the group consisting of amino group-containing silane coupling agents, hydrolysates thereof, and polymers thereof; fluorine (C); and a cationic urethane resin (D).

The content of (A) is preferably 20 to 10000 ppm by mass in total in terms of metal, and the pH of the chemical conversion treatment agent is preferably 1.5 to 6.5.

Preferably, the total content of the component (B) is 5 to 5000 mass ppm in terms of solid content concentration, the content of the component (D) is 5 to 5000 mass ppm in terms of solid content concentration, and the mass ratio ((B)/(D)) of the component (B) to the solid content (D) is 0.0002 to 5000.

Preferably, the coating composition further contains at least one adhesion and corrosion resistance imparting agent selected from the group consisting of magnesium ions, zinc ions, calcium ions, aluminum ions, gallium ions, indium ions, and copper ions.

The present invention also relates to a pretreatment for coating treatment for treating an object to be treated with the chemical conversion treatment agent.

The present invention also relates to a metal member treated by the pretreatment coating method.

Effects of the invention

According to the present invention, it is possible to provide a chemical conversion treatment agent that has a small burden on the environment and can ensure good post-coating corrosion resistance regardless of the treatment target.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.

(chemical treatment agent)

The chemical conversion treatment agent according to the present embodiment forms a chemical conversion coating on a metal surface as a treatment object, and provides a desired post-coating corrosion resistance. The metal to be treated is not particularly limited, and can be used for all metals such as iron, zinc, and aluminum. The chemical conversion treating agent according to the present embodiment is particularly preferably used for iron-based high-pressure steel sheets and hot-rolled steel sheets. Such iron-based high-pressure steel sheets and hot-rolled steel sheets are widely used for automobile chassis parts and the like, but since an oxide film is formed on the surface as described later, it is difficult to form a uniform chemical film on the surface.

The chemical conversion treatment agent according to the present embodiment is a chemical conversion treatment agent that does not substantially contain phosphate ions or harmful heavy metal ions, but can form a uniform chemical conversion coating on the surface of a high-pressure steel sheet or a hot-rolled steel sheet. Therefore, good corrosion resistance of the treated object after coating can be ensured.

The chemical conversion treatment agent according to the present embodiment contains at least one (a) selected from the group consisting of zirconium, titanium, and hafnium, at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof, fluorine (C), and a cationic urethane resin (D).

At least one (a) selected from the group consisting of zirconium, titanium and hafnium is a chemical conversion coating forming component, and by forming a chemical conversion coating containing at least one selected from the group consisting of zirconium, titanium and hafnium on a substrate, the corrosion resistance and wear resistance of the substrate can be improved, and the adhesion to a coating film can be further improved.

For example, when a surface treatment of a metal substrate is performed using a chemical conversion treatment agent containing zirconium, ZrF is attracted by metal ions eluted from the chemical conversion treatment agent by a dissolution reaction of the metal₆ ^2-The fluorine (2) also generates a zirconium hydroxide or oxide due to an increase in the interface pH, and it is considered that the zirconium hydroxide or oxide precipitates on the surface of the substrate. As described above, the chemical conversion treatment agent in the present embodiment is a reactive chemical conversion treatment agent, and therefore can be used for immersion treatment of an object to be treated having a complicated shape. Further, when the surface treatment is carried out by using the chemical conversion treatment agent, chemical reaction can be obtainedSince the chemical conversion coating film is firmly adhered to the object to be treated, the chemical conversion coating film may be washed with water after the treatment.

The source of the zirconium is not particularly limited, and may be K₂ZrF₆Alkali metal fluorozirconates; (NH)₄)₂ZrF₆Isofluorozirconates; h₂ZrF₆Soluble fluorozirconate such as fluorozirconic acid; zirconium fluoride; zirconia, and the like.

The supply source of the titanium is not particularly limited, and examples thereof include alkali metal fluorotitanate, (NH)₄)₂TiF₆Isofluorotitanate; h₂TiF₆Soluble fluorotitanates such as isofluorotitanic acid; titanium fluoride; titanium oxide, and the like.

The source of the hafnium is not particularly limited, and examples thereof include H₂HfF₆Isofluorohafnic acid; hafnium fluoride, and the like.

The source of at least one selected from the group consisting of zirconium, titanium and hafnium preferably has ZrF as a source thereof, from the viewpoint of high film-forming ability₆ ^2-、TiF₆ ^2-、HfF₆ ^2-A compound of at least one of the group consisting of.

The total content of at least one selected from the group consisting of zirconium, titanium and hafnium contained in the chemical conversion agent according to the present embodiment is preferably within a range of a lower limit of 20 mass ppm and an upper limit of 10000 mass ppm in terms of metal. If the amount is less than 20 mass ppm, the performance of the resultant chemical conversion coating is insufficient, and if it exceeds 10000 mass ppm, further effects cannot be expected, which is economically disadvantageous. The lower limit is more preferably 50 mass ppm, and still more preferably 100 mass ppm. The upper limit is more preferably 2000 mass ppm, and still more preferably 500 mass ppm.

At least one (B) selected from the group consisting of amino group-containing silane coupling agents, hydrolysates thereof, and polymers thereof is a compound having at least one amino group in the molecule and a siloxane bond. The adhesion between the chemical conversion coating and the coating film is improved by the action of at least one (B) selected from the group consisting of the amino group-containing silane coupling agent, the hydrolysate thereof, and the polymer thereof.

The reason why such an effect is produced is presumed to be: hydrolyzing to hydrolyze silanol-forming groups and to cause hydrogen bond adsorption with the surface of the metal substrate; and the adhesion of the chemical film to the metal substrate is improved by the action of the amino group. It can be considered that: at least one (B) selected from the group consisting of amino group-containing silane coupling agents, hydrolysates thereof, and polymers thereof contained in the chemical conversion coating film as described above has an effect of improving the mutual adhesion by acting on both the metal base material and the coating film.

The amino group-containing silane coupling agent is not particularly limited, and examples thereof include known silane coupling agents such as N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethyl-butylene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N, N-bis [3- (trimethoxysilyl) propyl ] ethylenediamine. KBM-602, KBM-603, KBE-603, KBM-903, KBE-9103, KBM-573 (manufactured by shin-Etsu chemical Co., Ltd.) and XS1003 (manufactured by Zhisuo Co., Ltd.) which are commercially available amino group-containing silane coupling agents can also be used.

The hydrolysate of the amino group-containing silane coupling agent can be produced by a conventionally known method, for example, a method in which the amino group-containing silane coupling agent is dissolved in ion-exchanged water and is adjusted to be acidic with an arbitrary acid. As the hydrolysate of the amino group-containing silane coupling agent, a commercially available product such as KBP-90 (manufactured by shin-Etsu chemical Co., Ltd.: active ingredient 32%) can be used.

The polymer of the amino group-containing silane coupling agent is not particularly limited, and examples thereof include commercially available products such as SILA ACE S-330(γ -aminopropyltriethoxysilane; available from Najksol corporation) and SILA ACE S-320(N- (2-aminoethyl) -3-aminopropyltrimethoxysilane; available from Najksol corporation).

The amount of at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof blended in the chemical conversion agent according to the present embodiment is preferably within a range of a lower limit of 5 mass ppm and an upper limit of 5000 mass ppm in total in terms of a solid content concentration. When the amount is less than 5 ppm by mass, sufficient coating film adhesion cannot be obtained. If it exceeds 5000 mass ppm, further effects cannot be expected, which is economically disadvantageous. The lower limit is more preferably 10 mass ppm, and still more preferably 50 mass ppm. The upper limit is more preferably 1000 mass ppm, and still more preferably 500 mass ppm.

Fluorine (C) functions as an etchant for the substrate. The source of fluorine (C) is not particularly limited, and examples thereof include fluorides such as hydrofluoric acid, ammonium fluoride, fluoroboric acid, ammonium bifluoride, sodium fluoride, and sodium hydrogen fluoride. Examples of the complex fluoride include hexafluorosilicate, and specific examples thereof include fluorosilicic acid, zinc fluorosilicate, manganese fluorosilicate, magnesium fluorosilicate, nickel fluorosilicate, iron fluorosilicate, calcium fluorosilicate, and the like.

The cationic urethane resin (D) forms a uniform chemical film on the surface of the metal to be treated. The cationic urethane resin (D) is a urethane resin having a cationic functional group, and examples of the cationic functional group include an amino group, an ammonium salt group, a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group, a trimethylamino group, and a triethylamino group, and among them, a quaternary ammonium salt group is preferable.

The polyol, isocyanate component and polymerization method of the polyurethane resin constituting the cationic polyurethane resin (D) are not particularly limited, and conventionally known components and methods can be used.

As the cationic polyurethane resin (D), commercially available products such as F2667D (available concentration 25% from first Industrial pharmaceutical Co., Ltd.), SUPERFLEX 620 (available concentration 30% from first Industrial pharmaceutical Co., Ltd.), SUPERFLEX650 (available concentration 26% from first Industrial pharmaceutical Co., Ltd.) and the like can be used.

If the cationic urethane resin (D) is contained only in the chemical conversion agent, a desired effect such as corrosion resistance after coating cannot be obtained, but when the cationic urethane resin (D) is contained in the chemical conversion agent together with at least one (B) selected from the group consisting of the amino group-containing silane coupling agent, the hydrolysate thereof, and the polymer thereof, a uniform chemical conversion coating film can be formed on the surface of the metal to be treated, and a desired corrosion resistance after coating of the metal member to be treated can be ensured.

Further, the cationic polyurethane resin (D) is preferably used without inhibiting the functions of the amino group-containing silane coupling agent, the hydrolysate thereof, and the polymer (B) thereof, because it does not compete with at least one selected from the group consisting of the amino group-containing silane coupling agent, the hydrolysate thereof, and the polymer (B) thereof.

The amount of the cationic urethane resin (D) to be incorporated in the chemical conversion treatment agent according to the present embodiment is preferably within a range of a lower limit of 5 mass ppm and an upper limit of 5000 mass ppm in terms of a solid content concentration. When the amount is less than 5 ppm by mass, sufficient coating film adhesion cannot be obtained. If it exceeds 5000 mass ppm, further effects cannot be expected, which is economically disadvantageous. The lower limit is more preferably 10 mass ppm, and still more preferably 50 mass ppm. The upper limit is more preferably 1000 mass ppm, and still more preferably 500 mass ppm.

In the chemical conversion treatment agent according to the present embodiment, the mass ratio ((B)/(D)) of at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof to the cationic polyurethane resin (D) is preferably 0.0002 to 5000. By setting the mass ratio ((B)/(D)) to the above range, it is possible to obtain an ideal post-coating corrosion resistance of the treatment object having the chemical film formed thereon. The mass ratio ((B)/(D)) is more preferably 0.01 to 100, and still more preferably 0.5 to 2.

The chemical conversion treatment agent according to the present embodiment preferably contains substantially no phosphate ions. The fact that phosphate ions are not substantially contained means that phosphate ions are not sufficiently contained to function as a component in the chemical conversion treatment agent, and since the chemical conversion treatment agent used in the present embodiment does not substantially contain phosphate ions, phosphorus that causes an environmental burden is not substantially used, and generation of sludge such as iron phosphate, zinc phosphate, or the like generated when a zinc phosphate-based treatment agent is used can be suppressed.

The chemical conversion treatment agent according to the present embodiment preferably has a pH within a range of a lower limit of 1.5 and an upper limit of 6.5. If the amount is less than 1.5, the film is excessively etched and a sufficient film cannot be formed. If the amount exceeds 6.5, etching is insufficient and a good film cannot be obtained. The lower limit is more preferably 2.0, and the upper limit is more preferably 5.5. The lower limit is more preferably 2.5, and the upper limit is more preferably 5.0. In order to adjust the pH of the chemical conversion agent according to the present embodiment, an acidic compound such as nitric acid or sulfuric acid, and a basic compound such as sodium hydroxide, potassium hydroxide, or ammonia may be used.

The chemical conversion treatment agent according to the present embodiment preferably further contains at least one selected from the group consisting of magnesium ions, zinc ions, calcium ions, aluminum ions, gallium ions, indium ions, and copper ions as an adhesion and corrosion resistance imparting agent. By containing the above adhesion and corrosion resistance imparting agent, a chemical film having further excellent adhesion and corrosion resistance can be obtained.

The content of at least one selected from the group consisting of magnesium ion, zinc ion, calcium ion, aluminum ion, gallium ion, indium ion and copper ion is preferably within a range of a lower limit of 1 mass ppm and an upper limit of 5000 mass ppm. If the content is less than the lower limit, a sufficient effect cannot be obtained, which is not preferable. If the content exceeds the upper limit, further improvement in the effect cannot be observed, which is economically disadvantageous and may lower the adhesion after coating. The lower limit is more preferably 25 mass ppm, and the upper limit is more preferably 3000 mass ppm.

The chemical conversion treatment agent may be used in combination with any other component as required, in addition to the above components. Examples of the usable component include silica and the like. By adding such a component, the corrosion resistance after coating can be improved.

< pretreatment method for coating >

The chemical conversion treatment in the pretreatment before coating method according to the present embodiment is not particularly limited, and may be performed by bringing a chemical conversion treatment agent into contact with a metal surface under normal treatment conditions. The treatment temperature in the chemical conversion treatment is preferably within a range of 20 ℃ at the lower limit and 70 ℃ at the upper limit. The lower limit is more preferably 30 ℃ and the upper limit is more preferably 50 ℃. The formation time in the formation treatment is preferably within a range of 5 seconds in the lower limit and 1200 seconds in the upper limit. The lower limit is more preferably 30 seconds, and the upper limit is more preferably 120 seconds. The chemical conversion treatment method is not particularly limited, and examples thereof include a dipping method, a spraying method, a roll coating method, and the like.

In the pretreatment for coating according to the present embodiment, the surface of the metal base material is preferably subjected to degreasing treatment and degreasing and post-washing treatment with water before the chemical conversion treatment, and is preferably subjected to chemical conversion and post-washing treatment with water after the chemical conversion treatment.

The degreasing treatment is a step for removing oil and stains adhering to the surface of the substrate, and is a dipping treatment performed at 30 to 55 ℃ for several minutes using a degreasing agent such as a phosphorus-free and nitrogen-free degreasing cleaning liquid. The degreasing treatment may be performed before the degreasing treatment as needed.

The post-degreasing water-washing treatment is a treatment performed by performing one or more spraying treatments using a large amount of water-washing water in order to wash the degreaser after the degreasing treatment.

The post-formation water washing treatment is carried out once or more so as not to adversely affect the adhesion, corrosion resistance, and the like after various subsequent coatings. In this case, the final water washing is suitably performed using pure water. In the post-formation washing treatment, either spray washing or immersion washing may be used, or washing may be performed by a combination of these methods.

The post-formation water-washing treatment may be followed by drying according to need by a known method, and then various coatings may be applied.

The pretreatment method for coating according to the present embodiment can eliminate the surface conditioning treatment required in the method for treatment with a zinc phosphate-based chemical conversion treatment agent which has been put into practical use in the past, and therefore, chemical conversion treatment of a metal base material can be performed in a smaller number of steps.

The metal substrate to be treated in the present embodiment is not particularly limited, and examples thereof include iron-based substrates, aluminum-based substrates, and zinc-based substrates. The iron, aluminum, and zinc-based substrates refer to iron-based substrates in which the substrate is made of iron and/or an alloy thereof, aluminum-based substrates in which the substrate is made of aluminum and/or an alloy thereof, and zinc-based substrates in which the substrate is made of zinc and/or an alloy thereof.

The pretreatment coating method according to the present embodiment is particularly preferably used for iron-based high-pressure steel sheets and hot-rolled steel sheets.

Since an oxide film having fine irregularities is formed on the surface of the hot-rolled steel sheet, and the oxide film is further porous with a large number of pores, it is difficult to coat the surface with a uniform chemical conversion coating. When the chemical conversion coating formed on the surface is not uniform, a potential difference is generated between the coated portion and the uncoated portion, and a uniform electrodeposition coating film cannot be formed when electrodeposition coating is performed. Therefore, in the conventional pretreatment method for coating using a chemical conversion treatment agent composed of zirconium or the like, the post-coating corrosion resistance equivalent to that of a zinc phosphate-based chemical conversion treatment agent cannot be ensured. In addition, since the high-pressure steel sheet similarly has an oxide film having fine irregularities formed on the surface thereof and contains a large amount of different metals, the potential difference becomes further large, and as a result, the coating with the chemical film becomes more uneven, and it becomes more difficult to ensure the corrosion resistance after coating.

However, according to the method of pretreatment before coating according to the present embodiment, a uniform chemical conversion coating can be formed even on an iron-based high-pressure steel sheet or a hot-rolled steel sheet, and the post-coating corrosion resistance equivalent to that of a chemical conversion treatment agent containing phosphate ions can be ensured. The mechanism for obtaining such an effect is not clear, but the reason is considered as follows: for example, the interaction between the cationic group of the cationic urethane resin (D) contained in the chemical conversion treatment agent and the surface of the steel sheet causes the concave portions and pores of the oxide film to be preferentially covered with the cationic urethane resin (D).

In the chemical conversion coating obtained by the pretreatment before coating method according to the present embodiment, the coating amount is preferably 0.1mg/m as the total amount of metals contained in the chemical conversion coating agent²Upper limit of 500mg/m²In the range of. If it is less than 0.1mg/m²It is not preferable because a uniform chemical conversion coating cannot be obtained. If it exceeds 500mg/m²Further effects cannot be obtained, which is disadvantageous in terms of economy. The lower limit is more preferably 5mg/m²The upper limit is more preferably 200mg/m²。

< Metal Member >

The metal base material treated by the pretreatment before coating is subjected to laser processing, press processing, or the like, to obtain a metal member which is subjected to forming processing according to various uses. Alternatively, the pretreatment coating method may be applied to a metal member which has been molded in advance. The application of the metal member according to the present embodiment is not particularly limited, but examples of the metal member for an automobile include a door, a hood, a roof, a hood, a fender, a trunk, and the like. Further, metal members used for motorcycles, buses, bicycles, and the like can be cited. In the above-described applications where high post-coating corrosion resistance is required, it is preferable to use a metal member treated by the pre-coating treatment method according to the present embodiment from the viewpoint of safety and appearance.

The coating that can be applied to the metal member treated by the pretreatment coating method is not particularly limited, and conventionally known coatings such as cationic electrodeposition coating, solvent coating, water-based coating, and powder coating can be used for the coating. For example, the cationic electrodeposition paint is not particularly limited, and conventionally known cationic electrodeposition paints made of an aminated epoxy resin, an aminated acrylic resin, a sulfonium epoxy resin, or the like can be applied. In particular, since at least one selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof is blended in the chemical conversion agent, a cationic electrodeposition coating material comprising a resin having a functional group that is reactive with or compatible with an amino group is preferable in order to further improve the adhesion between the electrodeposition coating film and the chemical conversion coating film.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within a range in which the object of the present invention can be achieved are also included in the present invention.

Examples

Next, the present invention will be described in further detail based on examples, but the present invention is not limited thereto. Unless otherwise specified, "ppm" described in examples and comparative examples means "mass ppm".

< example 1 >

A commercially available cold-rolled steel sheet (SPC270, manufactured by Testpanel, Japan, 70 mm. times.150 mm. times.0.8 mm) was used as a substrate, and pre-coating treatment was performed under the following conditions.

(1) Pretreatment before coating

Degreasing treatment: the resultant was impregnated with 2% by mass of "SURF CLEANER 53" (degreaser available from Japan SURF CHEMICALS Co., Ltd.) at 40 ℃ for 2 minutes.

And (3) water washing treatment after degreasing: the spray treatment was carried out with tap water for 30 seconds.

Formation treatment: a chemical conversion treatment agent having a zirconium (A) concentration of 100 mass ppm, an amino group-containing silane coupling agent (B) concentration of 100 mass ppm and a cationic polyurethane resin (D) concentration of 100 mass ppm was prepared by using fluorozirconic acid and KBM-603(N-2 (aminoethyl) 3-aminopropyltrimethoxysilane: available from shin-Etsu chemical Co., Ltd.) as the amino group-containing silane coupling agent, and F2667D (available from first Industrial pharmaceutical Co., Ltd.: available concentration of 25%) as the cationic polyurethane resin. The pH was adjusted to 4 using sodium hydroxide. The temperature of the chemical conversion treatment agent was adjusted to 40 ℃, and the base material was subjected to immersion treatment for 60 seconds. The amount of the coating film in the initial stage of the treatment was 13.4mg/m²。

And (3) washing treatment after formation: the spray treatment was carried out with tap water for 30 seconds. Further, the spray treatment was carried out for 10 seconds with ion-exchanged water. Then, electrodeposition coating was performed in a wet state. The coating amount was analyzed by drying the cold-rolled steel sheet after the water washing treatment in an electric drying furnace at 80 ℃ for 5 minutes, and then using "zsxprimus II" (X-ray analyzer, manufactured by physics, inc.) as the total amount of metals contained in the chemical conversion treatment agent.

(2) Coating of

1m of formation treatment agent per 1L²After the treatment of the cold-rolled steel sheet, electrodeposition coating was performed so that the dry film thickness became 20 μm using "POWERNICS 310" (cationic electrodeposition coating manufactured by Nippon Paint Industrial Coatings), and the steel sheet was baked by heating at 170 ℃ for 20 minutes after washing to prepare a test sheet.

< examples 2 to 7 >

Test panels were produced in the same manner as in example 1 except that the metal base material was changed to cold rolled steel sheet (SPC780, manufactured by japanese Testpanel, 70mm × 150mm × 0.8mm), hot rolled steel sheet (SPH270, SPH440, SPH590, manufactured by japanese Testpanel, 70mm × 150mm × 0.8mm), galvanized steel sheet (GA270, manufactured by japanese Testpanel, 70mm × 150mm × 0.8mm), and 6000 series aluminum sheet (manufactured by japanese Testpanel, 70mm × 150mm × 0.8mm), as shown in table 1.

Regarding the types of the base materials shown in tables 1 and 2, SPC denotes the cold-rolled steel sheet, SPH denotes the hot-rolled steel sheet, GA denotes the galvanized steel sheet, and AL denotes the 6000-series aluminum sheet.

< examples 8 to 13 >

Test sheets were produced in the same manner as in example 1, except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, and the silane coupling agent (B) concentration and the cationic urethane resin (D) concentration were 1 mass ppm, 5 mass ppm, and 50 mass ppm, respectively, as shown in table 1.

< examples 14 and 15 >

Test plates were produced in the same manner as in example 1 except that SUPERFLEX 620 (product of first industrial pharmaceutical company, effective concentration 30%) or SUPERFLEX650 (product of first industrial pharmaceutical company, effective concentration 26%) was used as the cationic polyurethane resin (D) as the metal base material as the hot-rolled steel sheet as shown in table 1.

< examples 16 to 21 >

Test plates were produced in the same manner as in example 1 except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, KBM-603(N-2 (aminoethyl) 3-aminopropyltrimethoxysilane: 100% in effective concentration, manufactured by shin-Etsu chemical Co., Ltd.) or KBM-903 (3-aminopropyltrimethoxysilane: 100% in effective concentration, manufactured by shin-Etsu chemical Co., Ltd.) was used as the silane coupling agent (B), and the silane coupling agent (B) and the cationic polyurethane resin (D) were used in concentrations shown in Table 1.

< examples 22 to 25 >

Test pieces were produced in the same manner as in example 1 except that KBE-903 (3-aminopropyltriethoxysilane: available concentration 100%: manufactured by shin-Etsu chemical Co., Ltd.) or XS1003(N, N-bis [3- (trimethoxysilyl) propyl ] ethylenediamine: available concentration 50%: manufactured by Nissan Seikagaku Co., Ltd.) was used as the silane coupling agent (B) and the cationic urethane resin (D) were used at the concentrations shown in Table 1, as shown in Table 1, with the zirconium (A) concentration being 500 mass ppm, the metal base material being the cold-rolled steel sheet or the hot-rolled steel sheet.

< examples 26 to 37 >

Test sheets were produced in the same manner as in example 1, except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, zinc nitrate (Zn) was used as the adhesion and corrosion resistance imparting material, and the zirconium (a) concentration, the silane coupling agent (B), and the cationic urethane resin (D) were set to the concentrations shown in tables 1 and 2, as shown in tables 1 and 2.

< examples 38 to 41 >

Test sheets were produced in the same manner as in example 1, except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, and the silane coupling agent (B) and the cationic urethane resin (D) were used at concentrations shown in table 2, as shown in table 2.

< comparative examples 1 to 8 >

Test sheets were produced in the same manner as in example 1, except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, and the silane coupling agent (B) or the cationic urethane resin (D) was used in the concentrations shown in table 2, as shown in table 2.

< reference example 1 >

A test plate was produced in the same manner as in example 1, except that the chemical conversion treatment agent was prepared without including the cationic urethane resin (D).

< reference examples 2 and 3 >

As shown in Table 2, test pieces were obtained in the same manner as in example 1 except that the metal base material was the cold-rolled steel sheet or the hot-rolled steel sheet, after degreasing and washing treatment, surface conditioning was performed at room temperature for 30 seconds using SURFFINE GL1 (manufactured by PAINT SURF CHEMICALS Co., Ltd.) and chemical conversion treatment was performed by using SURFMINE SD-6350 (zinc phosphate chemical conversion treatment agent manufactured by PAINT SURF CHEMICALS Co., Ltd.) in place of the chemical conversion treatment agent and immersion treatment was performed at 35 ℃ for 2 minutes.

The test boards of examples 1 to 41, comparative examples 1 to 8, and reference examples 1 to 3 obtained as described above were used to carry out the following evaluation tests.

[ Secondary adhesion test (SDT) ]

After scribing two parallel longitudinal cutting lines up to the substrate on the resulting test panel, the panel was immersed in a 5% NaCl aqueous solution at 50 ℃ for 480 hours. Then, the cut portion was peeled off with tape, and the peeling of the paint was observed. The peeled state was evaluated according to the following evaluation criteria, and an evaluation of 2 or more was regarded as passed. The results are shown in tables 1 and 2.

1: without peeling

2: slight peeling

3: peeling width of 3mm or more

[ Salt Spray Test (SST) ]

After the cross-cut line up to the substrate was scribed on the resulting test panel, a 5% aqueous NaCl solution was continuously sprayed for 240 hours in a saline spray tester maintained at 35 ℃. Then, the expanded width from the cut portion was measured. The above-mentioned expansion width was equal to or less than that of the zinc phosphate surface-treating agents shown in reference examples 2 and 3. The results are shown in tables 1 and 2.

[ composite Cycle Corrosion Test (CCT) ]

After the cross cutting line up to the substrate was scribed on the resulting test panel, a composite cyclic corrosion test was performed. As to the test method, the composite test was carried out for 100 cycles in accordance with the regulations of JASO M609-91. After the test, the expanded width from the cut portion was measured. The above-mentioned expansion width was equal to or less than that of the zinc phosphate surface-treating agents shown in reference examples 2 and 3. The results are shown in tables 1 and 2.

[ Table 1]

[ Table 2]

As is clear from the comparison between examples 1 to 41 and comparative examples 1 to 5, 7 and 8, the metal substrates treated with the chemical conversion treatment agents of examples 1 to 41 were superior in secondary adhesion (SDT) to the metal substrates treated with the chemical conversion treatment agents of comparative examples 1 to 5, 7 and 8. From the results, it was confirmed that when the chemical conversion treatment agent contains at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof, it is possible to impart a desired post-coating corrosion resistance to the metal substrate treated with the chemical conversion treatment agent.

Further, since the metal substrates treated with the chemical conversion treatment agents of comparative examples 1 and 3 and the metal substrates treated with the chemical conversion treatment agents of comparative examples 7 and 8 did not have satisfactory secondary adhesion (SDT), it was confirmed that, when the chemical conversion treatment agent did not contain at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof, it was not satisfactory even if the content of the cationic urethane resin (D) was increased, and by using the cationic urethane resin (D) in combination with at least one (B) selected from the group consisting of an amino group-containing silane coupling agent, a hydrolysate thereof, and a polymer thereof, it was possible to impart satisfactory post-coating corrosion resistance to the metal substrates treated with the chemical conversion treatment agents.

As is clear from comparison of examples 1 to 41 with comparative example 6, the metal substrates treated with the chemical conversion treatment agents of examples 1 to 41 were superior to the metal substrates treated with the chemical conversion treatment agent of comparative example 6 in the results of the composite Cycle Corrosion Test (CCT). From the results, it was confirmed that when the cationic urethane resin (D) is contained in the chemical conversion treatment agent, a desired post-coating corrosion resistance can be imparted to the metal substrate treated with the chemical conversion treatment agent.

As is clear from comparison between examples 1 to 41 and reference examples 1 to 3, the metal substrates treated with the chemical conversion treatment agents of examples 1 to 41 showed results of Salt Spray Test (SST) and combined Cycle Corrosion Test (CCT) equal to or higher than those of the metal substrates treated with the chemical conversion treatment agents of reference examples 1 to 3. From the results, it was confirmed that the metal base material treated with the chemical conversion treatment agent of the present invention had excellent post-coating corrosion resistance equal to or more than the metal base material treated by the conventional pre-coating treatment method used for the cold-rolled steel sheet of reference example 1 and the conventional zinc phosphate-treated metal base materials of reference examples 2 to 3.

Further, as is clear from comparison of examples 1 to 7, the metal substrates treated with the chemical conversion treating agents of examples 1 to 7 all had excellent post-coating corrosion resistance. From the results, it was confirmed that the chemical conversion treatment agent of the present invention can ensure excellent post-coating corrosion resistance regardless of the treatment target.

Claims

1. A chemical conversion treatment agent comprising: at least one (A) selected from the group consisting of zirconium, titanium and hafnium; at least one (B) selected from the group consisting of amino group-containing silane coupling agents, hydrolysates thereof, and polymers thereof; fluorine (C); and a cationic urethane resin (D).

2. The chemical conversion treatment agent according to claim 1, wherein the content of (A) is 20 to 10000 ppm by mass in total in terms of metal,

the pH value of the chemical conversion treatment agent is 1.5-6.5.

3. The chemical conversion treating agent according to claim 1 or 2, wherein the content of (B) is 5 to 5000 ppm by mass in total in terms of solid content,

the content of (D) is 5-5000 mass ppm in terms of solid content concentration,

the mass ratio of the solid component of (B) to the solid component of (D), (B)/(D), is 0.0002 to 5000.

4. The chemical conversion treatment agent according to any one of claims 1 to 3, further containing at least one adhesion and corrosion resistance imparting agent selected from the group consisting of magnesium ions, zinc ions, calcium ions, aluminum ions, gallium ions, indium ions, and copper ions.

5. A pretreatment method for coating, comprising treating a material to be treated with the chemical conversion treating agent according to any one of claims 1 to 4.

6. A metal member treated by the pretreatment coating method according to claim 5.