JP2005325401A - Surface treatment method for zinc or zinc alloy coated steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treatment method for zinc or zinc alloy coated steel where excellent corrosion resistance, coating adhesion or the like can be imparted to a zinc or zinc alloy coated steel component after chemical conversion treatment, and to provide zinc or zinc alloy coated steel obtained thereby. <P>SOLUTION: The surface treatment method for zinc or zinc alloy coated steel is composed of a process where a chemical film is formed on the surface of the metallic object to be treated by chemical conversion treatment reaction with a chemical conversion treatment agent comprising a zirconium-containing compound, a fluorine-containing compound, and at least one kind selected from the group consisting of aluminum ion, vanadium ion and magnesium ion. The chemical conversion treatment reaction is performed by cathode electrolytic treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a surface treatment method for zinc or zinc-based alloy plated steel material, and to a zinc or zinc-based alloy plated steel material obtained thereby.

Zinc-plated steel materials and zinc-based alloy-plated steel materials have conventionally been widely rust-proofed by chromate treatment using hexavalent chromate, etc., and are resistant to organic solvents, fingerprints, and scratches as needed. In order to impart lubricity and the like, a coating layer made of an organic resin has been formed on a chromate-treated film.

In recent years, against the background of increasing environmental problems, there has been a movement to omit chromate treatment that has been conventionally applied to galvanized steel materials and zinc-based alloy plated steel materials. Since the chromate-treated film itself has a high degree of corrosion resistance and paint adhesion, if the chromate treatment is not performed, these performances are expected to be significantly reduced. For this reason, it has been required that the surface of galvanized steel materials and zinc-based alloy plated steel materials be subjected to rust prevention treatment instead of chromate treatment to form a rust prevention film having good corrosion resistance and paint adhesion. It was.

In addition, when forming a galvanized steel material having a chemical conversion film obtained by chemical conversion treatment or a zinc-based alloy plated steel material, cracking or peeling of the chemical conversion film on the steel material may occur, such as cracking or peeling. When using a molded product having a chemical conversion film in which corrosion occurs, performance such as corrosion resistance and coating film adhesion may deteriorate. For this reason, it is desired to develop a surface treatment method that suppresses the occurrence of cracking, peeling, etc. when molded, and has performance such as excellent corrosion resistance and coating film adhesion even for molded products. Yes.

As a metal surface treatment method, Patent Documents 1 and 2 disclose a surface treatment method by an electrolytic reaction using a phosphate compound or a titanium-based treatment agent. However, these techniques are not surface treatment methods using a zirconium treating agent. Moreover, it does not provide a surface treatment method for the purpose of improving the corrosion resistance, coating film adhesion and the like.

Patent Document 3 contains (A) a compound containing at least one of Ti, Zr, Hf and Si, (B) a fluorine-containing compound as a source of HF, and Ti in the compound of component (A), The ratio K = A / B of the total molar weight A of the metal elements of Zr, Hf and Si to the molar weight B when all fluorine atoms in the fluorine-containing compound of the component (B) are converted to HF is 0.06. There is disclosed a metal surface treatment method in which a surface treatment composition in the range of ≦ K ≦ 0.18 is brought into contact with a metal surface.

However, when the chemical conversion treatment is performed by the surface treatment method disclosed herein, a large amount of excess fluorine and alkali metal are present in the solution. Therefore, even if an electrolytic voltage is applied to the material to be treated, the cathode Since the protective effect is difficult to obtain and a chemical conversion film containing a relatively large amount of fluoride is formed, the corrosion resistance cannot be sufficiently satisfied.

Therefore, as a surface treatment that replaces the chromate treatment, it is an environmentally preferable rust prevention treatment, and a surface treatment of a galvanized steel material or a zinc-based alloy plated steel material that can form a rust-proof film having good corrosion resistance and paint adhesion Development of a method was desired.

JP 2000-234200 A JP 2002-194589 A International Publication No. 02/103080 Pamphlet

In view of the above situation, the present invention provides a surface treatment method for zinc or zinc-based alloy plated steel that can impart high corrosion resistance and coating adhesion to the zinc or zinc-based alloy plated steel after chemical conversion treatment, and zinc obtained thereby. Or it aims at providing a zinc system alloy plating steel material.

The present invention provides a chemical conversion treatment on a metal workpiece surface by a chemical conversion treatment with a chemical conversion treatment agent comprising a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. A surface treatment method for zinc or zinc-based alloy-plated steel material comprising a step of forming a film, wherein the chemical conversion treatment reaction is performed by cathode electrolytic treatment. is there.

In the cathode electrolysis treatment, the concentration of the zirconium-containing compound in the chemical conversion treatment agent is 100 to 10,000 ppm in terms of zirconium metal, and the ratio of the mass as the total zirconium metal to the mass of the total fluorine (zirconium amount / fluorine amount) is 0.2. It is preferable that the pH is adjusted to 1 to 6 and adjusted to 1 to 1.0.

The cathode electrolytic treatment is preferably performed by adjusting the concentration of at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions in the chemical conversion treatment agent to 50 to 500 ppm in terms of metal. .

The chemical conversion treatment agent further contains phosphate ions, and the cathode electrolytic treatment is performed by adjusting the concentration of the phosphate ions to 10 to 1000 ppm in terms of diphosphorus pentoxide. Is preferred.

It is preferable to perform the step of forming an organic film after the step of forming the chemical conversion film.
The present invention is also a zinc or zinc-based alloy plated steel material having a chemical conversion treatment film obtained by the surface treatment method for zinc or zinc-based alloy plated steel material.
Hereinafter, the present invention will be described in detail.

The surface treatment method for zinc or zinc-based alloy plated steel according to the present invention includes a chemical conversion treatment agent comprising a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. The chemical conversion film is formed by cathodic electrolytic treatment of the surface of the metal workpiece. When reacted by electrolytic treatment, it becomes a dense and uniform film as compared with a chemical conversion film by electroless treatment. For this reason, the molded product obtained by molding the zinc or zinc-based alloy-plated steel obtained by the surface treatment method of zinc or zinc-based alloy-plated steel has excellent performance such as corrosion resistance and paint adhesion. Can be granted.

When an electrolytic reaction is performed with the chemical conversion treatment agent, a corrosion-resistant chemical conversion film having extremely excellent corrosion resistance is obtained, and a corrosion resistance superior to that obtained by an electrolytic reaction of a conventional chemical conversion treatment agent is obtained. For this reason, use in a wide range is expected and preferable.

When a film is formed by electroless treatment, a zirconium-based chemical film containing a relatively large amount of fluorine is formed, and a film having poor corrosion resistance is formed. On the other hand, when electrolytically treating a chemical conversion treatment agent containing a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions, the main surface is a metal surface. In this case, a hydrogen generation reaction occurs and the material metal is protected like a cathode, so that it is not etched and no fluoride of the metal to be processed is generated. Therefore, in the vicinity of the metal surface, deposition of a relatively stable zirconium oxide film occurs due to the hydrolysis of zirconium complex ions, and a dense and stable protective film with a low fluorine content is formed. It is presumed that this can be improved.

The surface treatment method for zinc or zinc-based alloy plated steel according to the present invention includes a chemical conversion treatment agent comprising a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. The chemical conversion treatment reaction comprises a step of forming a chemical conversion film on the surface of the zinc or zinc-based alloy plated steel material, and the chemical conversion treatment reaction is carried out by cathode electrolytic treatment. Thereby, excellent performances such as corrosion resistance and paint adhesion can be imparted to a molded product obtained by molding the steel obtained by the surface treatment method for zinc or zinc-based alloy plated steel.

The zirconium-containing compound is not particularly limited as long as it is a compound containing zirconium, and examples thereof include fluorozirconic acid or its lithium, sodium, potassium, ammonium salt, zirconium fluoride, and zirconium oxide. These may be used alone or in combination of two or more.

The fluorine-containing compound is not particularly limited as long as it is a fluorine-containing compound. Besides the above-mentioned zirconium fluoride, etc., hydrofluoric acid, ammonium fluoride, ammonium hydrofluoride, sodium fluoride, fluoride A sodium hydrate etc. can be mentioned. These may be used alone or in combination of two or more.

In the surface treatment method for zinc or zinc-based alloy-plated steel material, the chemical conversion treatment agent contains at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. Thereby, performance, such as corrosion resistance of a molded product obtained by shape | molding the steel material after a chemical conversion process, and coating-film adhesiveness, can be improved more.

The compound serving as a source of aluminum ions contained in the chemical conversion treatment agent used in the surface treatment method for zinc or zinc-based alloy plated steel is not particularly limited. For example, aluminum fluoride, aluminum oxide, aluminum sulfate, Examples thereof include aluminates such as aluminum silicate and sodium aluminate. These may be used alone or in combination of two or more.

The compound that is a source of vanadium ions contained in the chemical conversion treatment agent used in the surface treatment method for zinc or zinc-based alloy plated steel is not particularly limited. For example, ammonium metavanadate, ammonium vanadate, pentoxide Examples thereof include divanadium, potassium hexafluorovanadate, ammonium hexafluorovanadate, and the like. These may be used alone or in combination of two or more.

The source of magnesium ions contained in the chemical conversion treatment agent used in the surface treatment method for zinc or zinc-based alloy plated steel is not particularly limited. For example, magnesium hydrogen phosphate, magnesium carbonate, magnesium oxide, hydroxide A magnesium etc. can be mentioned. These may be used alone or in combination of two or more.

It is preferable that the chemical conversion treatment agent used by the surface treatment method of the said zinc or zinc type alloy plating steel materials contains an aluminum ion. Thereby, performance, such as corrosion resistance of a molded product obtained by shape | molding the steel material after a chemical conversion process, and coating-film adhesiveness, can be improved more.

In the cathode electrolytic treatment in the present invention, the chemical conversion treatment agent in the treatment bath is adjusted to have a lower limit of 50 ppm and an upper limit of 500 ppm in terms of metal, at least one concentration selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. Is preferably performed. When it is less than 50 ppm, when the steel material after the chemical conversion treatment is molded, there is a possibility that performance such as corrosion resistance and paint adhesion of the molded product may not be improved. Even if it exceeds 5000 ppm, these performance improvements may not be observed. The lower limit is more preferably 100 ppm, and the upper limit is more preferably 400 ppm. In addition, the said metal conversion density | concentration is a density | concentration of the total amount of aluminum ion, vanadium ion, and magnesium ion.

In the surface treatment method for zinc or zinc-based alloy-plated steel material of the present invention, the cathode electrolytic treatment has a concentration of the zirconium-containing compound in the chemical conversion treatment agent as a lower limit of 100 ppm in terms of zirconium metal, an upper limit of 10000 ppm, The total fluorine content (zirconium amount / fluorine amount) is preferably adjusted so that the lower limit is 0.2, the upper limit is 1.0, and the pH is lower limit 1 and upper limit 6. By performing the cathode electrolytic treatment with such adjustment, a chemical conversion film having a relatively small fluorine content can be formed, and therefore the corrosion resistance of the molded product can be further improved.

In the cathode electrolytic treatment, as a method for adjusting the concentration of the zirconium-containing compound and the amount of zirconium / fluorine to the specified range, for example, the total zirconium concentration in the chemical conversion treatment agent is determined by using an atomic absorption analyzer. Can be adjusted by supplying the zirconium-containing compound and the fluorine-containing compound into the treatment bath while measuring using an ion chromatograph. Moreover, as a method of adjusting the said pH to the said regulation range, it can adjust, for example by supplying nitric acid or ammonium hydroxide in a processing bath, measuring using a pH meter.

In the cathode electrolytic treatment in the present invention, the chemical conversion treatment agent in the treatment bath is preferably adjusted such that the concentration of the zirconium-containing compound is in the range of a lower limit of 100 ppm and an upper limit of 10,000 ppm in terms of zirconium metal. When it is less than 100 ppm, when the steel material after the chemical conversion treatment is formed, the performance of the molded product such as corrosion resistance and paint adhesion may be deteriorated. Moreover, when it mixes exceeding 10,000 ppm, the effect beyond it cannot be expected and it is uneconomical. The lower limit is more preferably 500 ppm, and the upper limit is more preferably 5000 ppm.

In the cathode electrolytic treatment in the present invention, the chemical conversion treatment agent in the treatment bath is composed of the mass as total zirconium metal (total mass of all zirconium as zirconium metal contained in the chemical conversion treatment agent) and the mass of total fluorine (chemical conversion treatment). The ratio (zirconium amount / fluorine amount) to the total mass of all fluorine contained in the agent is preferably adjusted to a lower limit of 0.2 and an upper limit of 1.0. If it is less than 0.2, the amount of fluorine becomes excessive, and the formation of a chemical conversion film by the cathode electrolytic treatment may be hindered. Moreover, since a chemical conversion film having a relatively large amount of fluorine is formed, the corrosion resistance and coating film adhesion of the molded product may be deteriorated. If it exceeds 1.0, the amount of total fluorine becomes insufficient, and precipitation of the metal salt may occur. The lower limit is more preferably 0.25, and the upper limit is more preferably 0.8.

In the cathode electrolytic treatment in the present invention, the chemical conversion treatment agent in the treatment bath is preferably adjusted to have a pH within a range of a lower limit of 1 and an upper limit of 6. When the pH is less than 1, there is a possibility that performance such as corrosion resistance and coating film adhesion of a molded product obtained by molding the steel after the chemical conversion treatment may not be observed. A pH exceeding 6 is not preferable because a sufficient amount of film cannot be obtained. The lower limit is preferably 2, and the upper limit is more preferably 5.

The chemical conversion treatment agent used in the surface treatment method of the zinc or zinc-based alloy plated steel material is at least one selected from the group consisting of the zirconium-containing compound, the fluorine-containing compound, the aluminum ion, vanadium ion, and magnesium ion. In addition, it is preferable that the phosphor further contains a phosphate ion. Thereby, performance, such as corrosion resistance of a molded product obtained by shape | molding the steel material after chemical conversion treatment, and coating-film adhesiveness, can be improved more.

In the chemical conversion treatment agent used in the surface treatment method of the zinc or zinc-based alloy plated steel material, the source of phosphate ions is not particularly limited. For example, phosphoric acid, ammonium phosphate, sodium phosphate or potassium phosphate And alkali metal phosphates such as alkali phosphates such as calcium phosphate and magnesium phosphate, and condensed phosphates. These may be used alone or in combination of two or more.

When the chemical conversion treatment agent used in the surface treatment method of the zinc or zinc-based alloy plated steel material contains phosphate ions, the concentration of the phosphate ions is calculated in terms of diphosphorus pentoxide. It is preferable to adjust the lower limit to 10 ppm and the upper limit to 1000 ppm. If it is less than 10 ppm, there is a possibility that performance such as corrosion resistance and coating film adhesion of the molded product will not be improved. Even if it exceeds 1000 ppm, there is a possibility that these performances are not improved. The lower limit is more preferably 50 ppm, and the upper limit is more preferably 700 ppm.

In the surface treatment method of the zinc or zinc-based alloy plated steel material, when the chemical conversion film is formed by electrolytic treatment using the chemical conversion treatment agent, in particular, the chemical conversion treatment agent contains a zirconium-containing compound, a fluorine-containing compound, and aluminum ions. In the case of containing phosphate ions, as a synergistic effect of including these, it is possible to remarkably improve performance such as corrosion resistance and coating film adhesion of a molded product obtained by molding the steel material after chemical conversion treatment. it can.

In addition to the above components, the chemical conversion treatment agent used in the surface treatment method for zinc or zinc-based alloy-plated steel is a metal ion such as titanium, manganese, silicon, zinc, iron, molybdenum, and trivalent chromium; tannic acid, Contains other rust inhibitors such as imidazoles, triazines, guanines, hydrazines, biguanides, phenolic resins, silane coupling agents, colloidal silica, amines, phosphoric acid; surfactants; chelating agents; resins, etc. It may be a thing.

In the surface treatment method for zinc or zinc-based alloy plated steel material of the present invention, the cathode electrolytic treatment is an electrolytic treatment by using an object to be treated as a cathode.

In the surface treatment method for zinc or zinc-based alloy plated steel material, the cathode electrolytic treatment preferably has a voltage of a lower limit of 0.1V and an upper limit of 40V. If it is less than 0.1 V, a sufficient protective chemical conversion film cannot be obtained, and there is a possibility that performance such as corrosion resistance and coating film adhesion of parts cannot be improved. If it exceeds 40V, the increase in the coating amount is saturated, which is disadvantageous in terms of energy, and there is a risk that problems such as burnout of parts may occur. The lower limit is more preferably 1V, and the upper limit is more preferably 30V.

In the surface treatment method for zinc or zinc-based alloy plated steel material, the cathode electrolytic treatment preferably has a current of 0.01 A / dm ^{2 as} a lower limit and 100 A / dm ^{2 as} an upper limit. If it is less than 0.01 A / dm ² , a sufficient protective chemical conversion film cannot be obtained, and there is a possibility that performance such as corrosion resistance and coating film adhesion of parts will not be improved. If it exceeds 100 A / dm ² , the effect of increasing the coating amount is saturated, which is disadvantageous in terms of energy, and there is a risk that problems such as burnout of parts may occur. The lower limit is more preferably 0.1 A / dm ² , and the upper limit is more preferably 80 A / dm ² .

In the surface treatment method for zinc or zinc-based alloy plated steel, the treatment time for the cathode electrolytic treatment is preferably a lower limit of 0.5 seconds and an upper limit of 60 seconds. If the time is less than 0.5 seconds, a sufficient protective chemical conversion film cannot be obtained, and there is a possibility that performance such as corrosion resistance and coating film adhesion of parts cannot be improved. If it exceeds 60 seconds, the effect of increasing the coating amount is saturated, which may be disadvantageous in terms of energy.

In the surface treatment method for zinc or zinc-based alloy plated steel material, the treatment temperature of the cathode electrolytic treatment is preferably a lower limit of 20 ° C. and an upper limit of 80 ° C. If it is less than 20 ° C., a sufficient protective chemical conversion film cannot be obtained, and there is a possibility that performance such as corrosion resistance and coating film adhesion of parts cannot be improved. If it exceeds 80 ° C., the effect of increasing the coating amount is saturated, which may be disadvantageous in terms of energy. The lower limit of the treatment temperature is not particularly controlled, and the treatment can be performed at room temperature.

In the cathode electrolytic treatment in the zinc or zinc-based alloy plated steel surface treatment method, the electrode used as the counter electrode is not particularly limited as long as it is an electrode that does not dissolve in the chemical conversion treatment agent. For example, stainless steel, nickel, platinum-plated titanium , Platinum plated niobium, oxide electrode, carbon and the like.

The surface treatment method for zinc or zinc-based alloy-plated steel material of the present invention may perform a step of forming an organic coating after performing the above-described step of forming a chemical conversion coating. When performing the process of forming the said organic membrane | film | coat, performance, such as corrosion resistance of a molded article obtained by shape | molding the steel material after chemical conversion treatment, and coating-film adhesiveness, can be improved more.

In the surface treatment method of the zinc or zinc-based alloy plated steel material, the treatment agent used in the step of forming the organic film is not particularly limited, and examples thereof include an aqueous resin. The aqueous resin means a water-soluble resin or a water-dispersible resin. The aqueous resin is not particularly limited, and examples thereof include an aqueous acrylic resin, an aqueous urethane resin, an aqueous polyester resin, an aqueous epoxy resin, an aqueous phenol resin, an aqueous olefin resin, and an aqueous ionomer resin. These may be used alone or in combination of two or more.

The metal workpiece to which the surface treatment method for zinc or zinc-based alloy plated steel of the present invention is applied is zinc or zinc-based alloy plated steel. By applying it to zinc or zinc-based alloy-plated steel materials, it is possible to further improve performances such as corrosion resistance and coating film adhesion of molded products obtained by molding the steel materials after chemical conversion treatment.

In the surface treatment method of the zinc or zinc-based alloy plated steel material, examples of the zinc or zinc-based alloy plated steel material include galvanized steel sheet, zinc-nickel plated steel sheet, zinc-iron plated steel sheet, zinc-chromium plated steel sheet, zinc -Zinc-type electroplating such as an aluminum-plated steel plate, a zinc-titanium-plated steel plate, a zinc-magnesium-plated steel plate, a zinc-manganese-plated steel plate, hot-dip plated steel plate, and the like.

The surface of the zinc or zinc-based alloy plated steel material can be subjected to degreasing treatment, post-degreasing water washing treatment, pickling treatment, pickling water washing treatment and the like before the cathode electrolytic treatment with the chemical conversion treatment agent.

The degreasing treatment is performed to remove oil and dirt adhering to the surface of the base material, and usually with a degreasing agent such as phosphorus-free and nitrogen-free degreasing cleaning liquid at about 30 to 55 ° C. for about several minutes. Immersion treatment is performed. If desired, a preliminary degreasing process can be performed before the degreasing process.

The post-degreasing rinsing treatment is performed by spraying once or more with a large amount of rinsing water in order to wash the degreasing agent after the degreasing treatment.

As the pickling treatment, for example, immersion treatment is usually performed for several minutes at 30 to 60 ° C. with an acid detergent such as hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid containing these oxidizing agents, or a mixed acid solution thereof. Examples of the oxidizing agent include nitric acid, nitrous acid, chloric acid, potassium permanganate, manganese dioxide, and iron sulfate. The water washing treatment after the pickling can be performed by a conventionally known method. Moreover, you may perform a water washing process after a cathode electrolytic process.

The present invention is also a zinc or zinc-based alloy plated steel material having a chemical conversion treatment film obtained by the surface treatment method for zinc or zinc-based alloy plated steel material. The zinc or zinc-based alloy-plated steel material of the present invention has excellent corrosion resistance and coating adhesion when a corrosion-resistant primer coating such as cationic electrodeposition coating, powder coating, and thermosetting resin is further formed on the chemical conversion film. It is. The coating that can be performed on the zinc or zinc-based alloy plated steel of the present invention is not particularly limited, and examples thereof include cationic electrodeposition coating, powder coating, and roll coating. The cationic electrodeposition coating is not particularly limited, and a conventionally known cationic electrodeposition coating made of an aminated epoxy resin, an aminated acrylic resin, a sulfoniumated epoxy resin, or the like can be applied.

The surface treatment method for zinc or zinc-based alloy plated steel according to the present invention includes a chemical conversion treatment agent comprising a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. Is a method comprising a step of forming a chemical conversion film by cathodic electrolytic treatment. Therefore, performance, such as corrosion resistance of a molded product obtained by shaping | molding the steel material after chemical conversion treatment, and coating-film adhesiveness, can be improved. In addition, since a metal such as hexavalent chromium is not used, it is also a preferable method in terms of environment. In particular, when a chemical conversion treatment agent containing a zirconium-containing compound, a fluorine-containing compound, aluminum ions, and phosphate ions is used, the synergistic effect exerted by these compounds improves the corrosion resistance of the molded article and the coating film adhesion. In particular, performance such as property can be improved.

Since the surface treatment method of the zinc or zinc-based alloy plated steel material of the present invention has the above-described configuration, the corrosion resistance and coating of the molded product obtained by molding the zinc or zinc-based alloy plated steel material after the chemical conversion treatment are performed. Performances such as film adhesion can be improved.

EXAMPLES Hereinafter, although an Example is hung up and demonstrated in more detail, this invention is not limited only to these Examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Examples 1-8, Comparative Examples 1-2
(Preparation of chemical conversion treatment agent)
As a zirconium-containing compound and a fluorine-containing compound, zirconic hydrofluoric acid, zircon ammonium fluoride, aluminum nitrate, ammonium hexafluorovanadate, magnesium nitrate, phosphoric acid are added, ion-exchanged water is added, and a chemical conversion treatment agent as shown in Table 1 Was prepared.

[Preparation of test plate]
A 70 mm × 150 mm × 0.8 mm EG bonde steel material (manufactured by Nippon Test Panel) was degreased by immersion for 30 seconds at 70 ° C. using a 3% aqueous solution of an alkaline degreasing agent (Surf Cleaner 322N8, Nippon Paint). After spraying with tap water for 30 seconds and washing with water, a pickling treatment agent (NP Conditioner 2000, Nippon Paint) 25% aqueous solution was used for immersion at 70 ° C. for 30 seconds for pickling. After spraying with tap water for 30 seconds and washing with water, the prepared chemical conversion treatment agent was subjected to cathodic electrolysis using SUS304 as a counter electrode under the conditions shown in Table 1.

In Comparative Example 1, immersion treatment was performed under the conditions shown in Table 1. In the base layer coating type chromate treatment of Comparative Example 2, 60% aqueous solution of NRC300 (manufactured by Nippon Paint Co., Ltd.) is applied so as to have a predetermined adhesion amount and dried so that the steel material arrival temperature becomes 60 ° C. in 5 seconds. A test plate was prepared.

The amount of zirconium in the coating (mg / m ² ) and the mass ratio of F / Zr in the coating were analyzed using “XRF1700” (Shimadzu X-ray fluorescence analyzer).

In the cathode electrolytic treatment, the concentration of the chemical conversion treatment agent in the treatment bath as zirconium metal, the mass ratio of zirconium / fluorine, and the pH were adjusted to the values shown in Table 1 as follows. .
The total zirconium concentration in the chemical conversion treatment agent in the treatment bath was measured using an atomic absorption spectrometer NOVA-A330 manufactured by Rigaku, and the total fluorine concentration was measured using an ion chromatograph DX-120 manufactured by Nippon Dionex Co., Ltd. It was adjusted by replenishing hydrofluoric acid into the treatment bath. Moreover, the pH of the chemical conversion treatment agent in the treatment bath was adjusted by supplying nitric acid or ammonium hydroxide to the treatment bath while measuring using a pH meter D-24 manufactured by Horiba.

[Evaluation of physical properties of test plate]
The test plate was evaluated for corrosion resistance by the following evaluation method, and the results are shown in Table 1.
<Corrosion resistance>
Based on JIS Z 2371, a 5% salt spray test (24, 48, 72, 120, 167, 215 hours) was performed, and the rust generation rate of the treated plate was examined after the test. The rust generation area on the surface of the treated plate was visually evaluated according to the following evaluation criteria.
10: No white rust generation 9: White rust generation area less than 10% 8: Less than 20% 7: Less than 30% 6: Less than 40% 5: Less than 50% 4: Less than 60% 3: 3: 70 Less than% 2: Less than 80% 1: Less than 90%

From Table 1, the test plate obtained in the example was excellent in corrosion resistance as compared with the test plate obtained in the comparative example.

Examples 9-16, Comparative Examples 3-4
[Preparation of test plate]
An organic film coating agent (SC7510 (solid content: 18%, manufactured by Nippon Paint Co., Ltd.)) is applied to each steel material that has been subjected to the electrolytic conversion treatment as described above with a bar coater so as to have a predetermined adhesion amount, A test plate was prepared by baking so that the steel material temperature reached 150 ° C. in 20 seconds, and the coating amount (mg / m ² ) of the organic coating was “RC142 type” (LECO total carbon analyzer). And analyzed.

[Evaluation of physical properties of test plate]
The test plate was evaluated for acid resistance, corrosion resistance, alkali resistance, paint adhesion, and film adhesion. The results are shown in Examples 11 to 20 and Comparative Examples 3 to 4 in Table 2. Evaluation was performed according to the following method.

<Acid resistance>
0.5 ml of a 1% aqueous acetic acid solution was dropped on the test plate with a dropper and allowed to stand at 55 ° C. in a 90% humidity atmosphere for 48 hours, and the appearance of the coating film was evaluated according to the following evaluation criteria.
◎: No change ○: Blackening area is less than 10% △: 10% or more and less than 30% ×: 30% or more

<Corrosion resistance>
The flat part of the test plate, and the end face part and the back face part of the processed part extruded 7 mm by the Erik Sentester are sealed with tape, sprayed with 5% saline at 35 ° C, and the white rust occurrence area ratio after 240 hours is determined. Evaluation was performed according to the following evaluation criteria.
◎: No white rust occurrence ○: White rust occurrence area is less than 10% △: 10% or more and less than 30% ×: 30% or more

<Alkali resistance>
The test plate was immersed in a 2% aqueous solution of 55 ° C alkaline degreasing agent (Surf Cleaner 53, Nippon Paint) for 2 minutes with stirring, then sealed with tape, and sprayed with 5% saline at 35 ° C for 120 hours. The subsequent white rust generation area ratio was evaluated according to the following evaluation criteria.
◎: No white rust occurrence ○: White rust occurrence area is less than 10% △: 10% or more and less than 30% ×: 30% or more

<Film adhesion>
Filament tape (manufactured by Slion Co., Ltd.) was applied to the test plate, and after standing for 3 days under the conditions of 40 ° C. and humidity 80%, the tape was forcibly peeled off, and the coating state was evaluated according to the following evaluation criteria.
◎: No peeling ○: Peeling area ratio is less than 10% Δ: Peeling area ratio is 10% or more and less than 50% ×: Peeling area ratio is 50% or more

<Coating adhesion>
A melamine alkyd paint (Super Rack 100, manufactured by Nippon Paint Co., Ltd.) was applied to the test plate surface with a bar coater to a dry film thickness of 20 μm, and baked at 120 ° C. for 25 minutes to prepare a coated plate. Next, immerse the coating plate in boiling water for 30 minutes, leave it for 24 hours, then extrude the coating plate with an elixir tester for 7 mm, apply a commercially available adhesive tape to the extrusion, and forcibly peel the coating state. Evaluation was performed according to the following evaluation criteria.
◎: No peeling ○: Peeling area ratio is less than 10% Δ: Peeling area ratio is 10% or more and less than 50% ×: Peeling area ratio is 50% or more

As is clear from the results of the examples from Table 2, the coated zinc or zinc-based alloy-plated steel material on which the film is formed by the method of the present invention has primary corrosion resistance, corrosion resistance after alkaline degreasing, film adhesion, and coating adhesion. It was excellent.

The surface treatment method for zinc or zinc-based alloy-plated steel material of the present invention can form a film excellent in coating adhesion, corrosion resistance, acid resistance, alkali resistance, and solvent resistance without using chromium. It can be suitably applied to zinc or zinc-based alloy plated steel.

Claims (6)

A chemical conversion film is formed on the surface of the metal object by a chemical conversion treatment with a chemical conversion treatment agent containing a zirconium-containing compound, a fluorine-containing compound, and at least one selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions. A surface treatment method of zinc or zinc-based alloy plated steel material comprising a process,
The chemical conversion treatment reaction is performed by cathodic electrolytic treatment, and the surface treatment method of zinc or zinc-based alloy plated steel material. In the cathode electrolysis treatment, the concentration of the zirconium-containing compound in the chemical conversion treatment agent is 100 to 10,000 ppm in terms of zirconium metal, and the ratio of the mass as the total zirconium metal to the mass of the total fluorine (zirconium amount / fluorine amount) is 0.2 to The method for surface treatment of zinc or zinc-based alloy plated steel according to claim 1, wherein the surface treatment is performed at 1.0 and pH is adjusted to 1-6. The cathode electrolytic treatment is performed by adjusting at least one concentration selected from the group consisting of aluminum ions, vanadium ions, and magnesium ions in the chemical conversion treatment agent to 50 to 500 ppm in terms of metal. 2. The surface treatment method for zinc or zinc-based alloy plated steel according to 2. The chemical conversion treatment agent further contains phosphate ions,
The surface treatment method for zinc or zinc-based alloy-plated steel material according to claim 1, 2 or 3, wherein the cathode electrolytic treatment is performed by adjusting the concentration of the phosphate ions to 10 to 1000 ppm in terms of diphosphorus pentoxide. . The method for surface treatment of zinc or zinc-based alloy plated steel according to claim 1, 2, 3, or 4, wherein the step of forming an organic coating is performed after the step of forming a chemical conversion coating. A zinc or zinc-based alloy-plated steel material having a chemical conversion coating obtained by the surface treatment method for zinc or zinc-based alloy-plated steel material according to claim 1, 2, 3, 4 or 5.