JP2020007617A - Chromium free metal surface treatment agent, metal surface treatment method and metal base material - Google Patents

Abstract

To provide: a chromium free metal surface treatment agent, capable of forming a coating excellent in corrosion resistance, adhesion and chemical resistance to a metal base material; a metal surface treatment method using the chromium free metal surface treatment agent; and a metal substrate subjected to surface treatment.SOLUTION: The chromium free metal surface treatment agent includes at least one kind of resin selected from (A) multi-silyl functional silane, (B) an amino group containing silane coupling agent, (C) inorganic compound particles, and (D) an aqueous cation urethane resin and aqueous cation acrylic resin. A mass ratio (resin solid content/silicon) of silicon in the (A) component and the (B) component to a resin solid content in the (D) component is 1-5.SELECTED DRAWING: None

Description

  The present invention relates to a chromium-free metal surface treatment agent, a metal surface treatment method, and a metal substrate.

  Conventionally, as a surface treatment agent for imparting corrosion resistance to a metal substrate, a chromium-based metal surface treatment agent such as a chromate treatment agent or a phosphoric acid chromate treatment agent has been known and is still widely used at present. However, in view of recent trends in environmental regulations, there is a possibility that chromium's toxicity, particularly carcinogenicity, will limit its use in the future.

  Therefore, various chromium-free metal surface treatment agents exhibiting the same corrosion resistance as chromium-based metal surface treatment agents have been developed.

  For example, Patent Literature 1 discloses that as a chromium-free metal surface treatment agent for a precoated steel sheet (PCM), (a) a silane coupling agent and a hydrolysis condensate thereof are used in an amount of 0.01 to 1 liter per metal surface treatment agent. 100 g / L, (b) 0.05 to 100 g / L of water-dispersible silica (solid content), (c) 0.01 to 50 g / L of zirconium compound as zirconium ion and / or 0 to 0 of titanium compound as titanium ion. One containing 0.11 to 50 g / L is disclosed.

Japanese Patent No. 4393660

  By the way, when a film is formed on a metal substrate using a chromium-free metal surface treatment agent, the formed film is required to have, in addition to corrosion resistance, adhesion to a metal substrate and a top coat, chemical resistance, and the like. Is done. In particular, when manufacturing a pre-coated steel sheet (PCM), a surface treatment is performed before the metal base material is formed. Therefore, the processed part is required to exhibit corrosion resistance and adhesion.

  However, the conventional chromium-free metal surface treatment agent does not have sufficient corrosion resistance, adhesion, and chemical resistance of the formed film, and has room for improvement.

  The present invention has been made in view of the above circumstances, and provides a chromium-free metal surface treatment agent capable of forming a film having excellent corrosion resistance, adhesion, and chemical resistance on a metal substrate. With the goal. Another object of the present invention is to provide a metal surface treatment method using the chromium-free metal surface treatment agent, and a metal substrate that has been subjected to a surface treatment.

The present invention provides the following components (A), (B), (C) and (D);
(A) polysilyl functional silane (B) amino group-containing silane coupling agent (C) inorganic compound particles (D) at least one resin selected from aqueous cationic urethane resin and aqueous cationic acrylic resin, The present invention relates to a chromium-free metal surface treating agent having a mass ratio (resin solids / silicon) of silicon in the components (A) and (B) to resin solids in the component (D) in the range of 1 to 5.

  The mass ratio of the component (A) to the component (B) (the component (A) / the component (B)) is preferably in the range of 0.2 to 8.7.

  The component (A) is preferably 1,2-bis (triethoxysilyl) -ethane.

  The component (B) includes 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- (aminoethyl)- It is preferably at least one selected from the group consisting of 3-aminopropylmethyldimethoxysilane.

The component (C) is preferably at least one selected from zirconium compound particles and titanium compound particles.
The average particle diameter of the component (C) is preferably 1 μm or less.

  Further, the present invention provides a step of applying the chromium-free metal surface treatment agent to the surface of a metal substrate, and a step of drying the chromium-free metal surface treatment agent applied to the metal substrate to form a film, And a metal surface treatment method comprising:

  The present invention also relates to a metal substrate having a film of the chromium-free metal surface treatment agent.

  ADVANTAGE OF THE INVENTION According to this invention, the chromium-free metal surface treatment agent which can form the film excellent in corrosion resistance, adhesiveness, and chemical resistance with respect to a metal base material can be provided. Further, according to the present invention, it is possible to provide a metal surface treatment method using the chromium-free metal surface treatment agent and a metal substrate subjected to the surface treatment.

  Hereinafter, the chromium-free metal surface treatment agent, the metal surface treatment method, and the metal substrate according to the present embodiment will be described in detail.

<Chromium-free metal surface treatment agent>
The chromium-free metal surface treatment agent according to the present embodiment includes the following components (A), (B), (C), and (D);
(A) polysilyl functional silane (B) amino group-containing silane coupling agent (C) inorganic compound particles (D) containing at least one resin selected from aqueous cationic urethane resins and aqueous cationic acrylic resins; The mass ratio (solid resin / silicon) of silicon in component (B) to the solid resin in component (D) is in the range of 1 to 5.

  According to the chromium-free metal surface treatment agent according to the present embodiment, a film having excellent corrosion resistance, adhesion, and chemical resistance can be formed on a metal substrate. In particular, the film formed using the chromium-free metal surface treatment agent according to the present embodiment exhibits good corrosion resistance and adhesion even in the processed part. For this reason, the chromium-free metal surface treatment agent according to the present embodiment is suitable, for example, as a coating base when manufacturing a pre-coated steel sheet (PCM).

[(A) Polysilyl-functional silane]
Examples of the polysilyl-functional silane as the component (A) include a compound having a plurality of silyl groups capable of generating a silanol group by hydrolysis. Preferred polysilyl-functional silanes include, for example, compounds represented by the following formula (I).

In the formula (I), R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. Examples of the monovalent organic group include a hydrocarbon group such as an alkyl group, an alkenyl group, a cycloalkyl group, and an aryl group; a hydrocarbon group having a functional group such as a hydroxyl group, an epoxy group, and an amino group; and a methyl group. And an alkyl group having 1 to 4 carbon atoms such as an ethyl group.

  In the above formula (I), Y represents a divalent organic group or an amine. Examples of the divalent organic group include an alkylene group, an alkyleneoxy group, an alkylenethio group, and a group containing these groups as a partial structure, and an alkylene group is preferable. The bivalent organic group preferably has 2 to 30 carbon atoms, and more preferably 2 to 12 carbon atoms.

In the above formula (I), X ¹ and X ² each independently represent a hydrolyzable group. Examples of the hydrolyzable group include an alkoxy group having 1 to 4 carbon atoms, and a methoxy group or an ethoxy group is preferable.

  In the above formula (I), a and b each independently represent an integer of 0 to 2, and 0 ≦ a + b ≦ 2. Further, c and d each independently represent an integer of 0 to 2, and 0 ≦ c + d ≦ 2. Each of a + b and c + d is preferably 0 or 1.

  Specific examples of the polysilyl-functional silane represented by the above formula (I) include bis (trimethoxysilyl) methane, 1,2-bis (trimethoxysilyl) ethane, and 1,2-bis (triethoxysilyl) ethane 1,6-bis (trimethoxysilyl) hexane, 1,6-bis (triethoxysilyl) hexane, 1,8-bis (trimethoxysilyl) octane, 1,8-bis (triethoxysilyl) octane, , 9-bis (trimethoxysilyl) nonane, 1,9-bis (triethoxysilyl) nonane, bis (trimethoxysilyl) amine, bis (triethoxysilyl) amine, bis (trimethoxysilylmethyl) amine, bis ( Triethoxysilylmethyl) amine, bis (trimethoxysilylpropyl) amine, bis (triethoxysilylpropyl) amine And the like. Among these, 1,2-bis (triethoxysilyl) ethane is preferable from the viewpoint of safety in handling, corrosion resistance and adhesion of the obtained film.

  One of these polysilyl functional silanes may be used alone, or two or more thereof may be used in combination. Further, the polysilyl-functional silane may be partially hydrolyzed and condensed.

  The content of the component (A) is not particularly limited, but is preferably 0.4 to 2.4% by mass in the total amount of the chromium-free metal surface treatment agent according to the present embodiment, and 0.6 to 1.7%. More preferably, it is mass%. When the content of the component (A) is 0.4% by mass or more, the corrosion resistance, adhesion to a metal substrate, and chemical resistance of the obtained film tend to be further improved. On the other hand, when the content of the component (A) is set to 2.4% by mass or less, the adhesion of the obtained film to the metal substrate tends to be improved.

[(B) Amino group-containing silane coupling agent]
As the amino group-containing silane coupling agent as the component (B), a conventionally known silane coupling agent having an amino group can be used without particular limitation. Specific examples of the amino group-containing silane coupling agent include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (Aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyl Examples include triethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and the like. Among these, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- (aminoethyl) -3-amino Propylmethyldimethoxysilane is preferred.

  One of these amino group-containing silane coupling agents may be used alone, or two or more thereof may be used in combination. Further, the amino group-containing silane coupling agent may be partially hydrolyzed and condensed.

  The content of the component (B) is not particularly limited, but the mass ratio of the component (A) to the component (B) (the component (A) / the component (B)) is in the range of 0.2 to 8.7. Is preferable, and it is more preferable that it is in the range of 0.5 to 3.0. By setting the mass ratio ((A) component / (B) component) to 0.2 or more, the corrosion resistance, adhesion to a metal substrate, and chemical resistance of the obtained film tend to be further improved. On the other hand, when the mass ratio (component (A) / component (B)) is 8.7 or less, the adhesion of the resulting film to the overcoat tends to be further improved.

[(C) inorganic compound particles]
Examples of the inorganic compound particles as the component (C) include zirconium compound particles and titanium compound particles. By containing a particulate inorganic compound, the corrosion resistance and chemical resistance of the resulting film tend to be improved as compared with the case of containing a non-particulate inorganic compound.

  Examples of the zirconium compound include zirconium oxide. Examples of the titanium compound include titanium oxide. One type of these inorganic compound particles may be used alone, or two or more types may be used in combination.

  The average particle size (D50) of the inorganic compound particles is preferably 1 μm or less, more preferably 10 to 300 nm.

  Commercially available products can also be used as the inorganic compound particles. Commercially available zirconium compound particles include “ZSL-20N”, “ZSL-10A”, “ZSL-10T”, “EP zirconium oxide”, “UEP zirconium oxide”, and “UEP-100 zirconium oxide” Manufactured by Ichizoku Kagaku Kogyo Co., Ltd.). Commercially available titanium compound particles include “CSB”, “CSB-M”, “SSP-25”, “SSP-20”, “SSP-M”, and “STA-100A” (all of which are Sakai Chemical Industries "DC-Ti", "DCN-Ti", "DCB-Ti" (above, manufactured by Fuji Titanium Industry Co., Ltd.);

  The content of the component (C) is not particularly limited, but is preferably 9.0 to 16.0% by mass based on the total solid content of the chromium-free metal surface treatment agent according to the present embodiment. By setting the content of the component (C) to 9.0% by mass or more, the chemical resistance of the obtained film tends to be improved. On the other hand, when the content of the component (C) is 16.0% by mass or less, the corrosion resistance of the obtained film and the adhesion to the metal substrate tend to be improved.

[(D) at least one resin selected from aqueous cationic urethane resins and aqueous cationic acrylic resins]
The aqueous cationic urethane resin and the aqueous cationic acrylic resin as the component (D) can be cationized in an aqueous medium such as a primary to tertiary amino group, an ammonium group, a sulfonium group, and a phosphonium group in the molecular structure. It has a cationic functional group. Specific examples of the cationic functional group include an amino group, a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group, a trimethylammonium group, and a triethylammonium group.

  The aqueous cationic urethane resin and the aqueous cationic acrylic resin are preferably added to the chromium-free metal surface treatment agent in the form of an emulsion finely dispersed in water.

  As the aqueous cationic urethane resin, a polyether polyol, a polyester polyol, a polycarbonate polyol, a polycaprolactone polyol, a polyol such as castor oil polyol, and an aliphatic, alicyclic, or an urethane resin obtained by polymerizing an aromatic polyisocyanate. Examples of the polyol include those obtained by using a polyol substituted with a cationic functional group such as a primary to tertiary amino group and an ammonium group.

  Commercial products can also be used as the aqueous cationic urethane resin. Commercially available water-based cationic urethane resins include “F-2667D”, “Superflex 650” (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.); “Techcoat WH-1515” (manufactured by Keishin Kasei Co., Ltd.); Is mentioned.

  Examples of the water-based cationic acrylic resin include a copolymer of a (meth) acrylate having a cationic functional group such as an amino group-containing (meth) acrylate and a quaternary ammonium group-containing (meth) acrylate, and another polymerizable unsaturated monomer. Coalescence. Examples of the amino group-containing (meth) acrylate include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N-methylaminoethyl (meth) acrylate, and N-methylaminopropyl ( (Meth) acrylate and the like. Examples of the quaternary ammonium group-containing (meth) acrylate include (meth) acryloyloxyethyltrimethylammonium chloride.

  Commercial products can also be used as the aqueous cationic acrylic resin. Examples of commercially available water-based cationic acrylic resins include “UW-550CS” and “UW-600” (all manufactured by Taisei Fine Chemical Co., Ltd.); “ACE-6” (manufactured by Murayama Chemical Laboratory Co., Ltd.); .

Among the aqueous cationic urethane resin and the aqueous cationic acrylic resin, an aqueous cationic urethane resin having a double bond in the structure is preferable. Since the aqueous cationic urethane resin having a double bond in the molecular structure has relatively high hydrophobicity, the corrosion resistance of the resulting film, the adhesion to the top coat, and the like tend to be further improved.
In addition, as a commercial item of the water-based cationic urethane resin which has a double bond in a structure, "F-2667D" (made by Dai-ichi Kogyo Seiyaku Co., Ltd.) etc. is mentioned.

  The component (D) is contained in an amount such that the mass ratio of the silicon in the components (A) and (B) to the resin solids in the component (D) (resin solids / silicon) is in the range of 1 to 5. You. By setting the mass ratio (resin solids / silicon) to 1 or more, the corrosion resistance, adhesion, and chemical resistance (particularly, alkali resistance) of the obtained film tend to be further improved. On the other hand, by setting the mass ratio (resin solids / silicon) to 5 or less, the chemical resistance (particularly, acid resistance) of the obtained film tends to be further improved.

  The chromium-free metal surface treatment agent according to the present embodiment may further contain a resin other than the aqueous cationic urethane resin and the aqueous cationic acrylic resin. However, the content of the other resin is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 0% by mass, based on the total amount of the resin.

[Other ingredients]
The chromium-free metal surface treatment agent according to the present embodiment may further contain other components in addition to the above components. Other components include a resin crosslinking agent for accelerating the curing of the resin, a surface conditioner used for leveling, and an antifoaming agent used for foam control.

[PH of chromium-free metal surface treatment agent]
The pH of the chromium-free metal surface treatment agent according to the present embodiment is preferably 7 or less, and more preferably 4 to 7. By adjusting the pH of the chromium-free metal surface treatment agent to 7 or less, the storage stability is further improved, and the chemical resistance (particularly, alkali resistance) of the obtained film tends to be further improved.

<Metal surface treatment method>
The metal surface treatment method according to the present embodiment includes a step of applying the chromium-free metal surface treatment agent according to the above-described embodiment to the surface of a metal substrate (hereinafter, also referred to as an “applying step”); (Hereinafter, also referred to as “drying step”) for drying the chromium-free metal surface treatment agent applied to the coating.

  In the application step, the above-described chromium-free metal surface treatment agent according to the present embodiment is applied to a metal substrate.

Examples of the metal substrate include hot-dip galvanized steel, electrogalvanized steel, aluminum-zinc alloy-plated steel, aluminum, and stainless steel.
The method for applying the chromium-free metal surface treatment agent to the metal material is not particularly limited, and examples thereof include roll coater coating, brush coating, roller coating, bar coater coating, and flow coating.

  In the drying step, the chromium-free metal surface treatment agent applied to the metal substrate is dried to form a film.

  The drying temperature is preferably, for example, 50 to 150 ° C, and more preferably 60 to 100 ° C.

  The applying step and the drying step may be performed simultaneously and in parallel. For example, a chromium-free metal surface treatment agent may be applied to a previously heated metal base material, and the chromium-free metal surface treatment agent may be dried using residual heat.

Coating weight of the coating, for example, it is preferably from 0.01 to 1.0 g / ^{m 2,} and more preferably 0.04 to 0.6 / ^{m 2.} When the amount of adhesion is 0.01 g / m ² or more, corrosion resistance and chemical resistance tend to be further improved. When the amount of adhesion is 1.0 g / m ² or less, corrosion resistance (particularly, corrosion resistance in a processed portion) and adhesion tend to be further improved.

  In the case of manufacturing a pre-coated steel sheet (PCM), for example, after a primer coating is applied on the formed film, a top coating can be applied. As both the primer coating and the top coating, a chrome-free coating is preferable.

<Metal base material>
The metal base material according to the present embodiment has the chromium-free metal surface treatment agent film according to the present embodiment described above. The metal substrate according to the present embodiment can be obtained by the above-described metal surface treatment method according to the present embodiment.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Preparation of chrome-free metal surface treatment agent>
[Examples 1 to 17, 24 to 33, Comparative Examples 1 to 14]
The type and amount (unit: g) of the component (A) shown in Tables 1 and 2 were mixed with 100 g of ion-exchanged water, and the pH was adjusted to 6 with acetic acid. By mixing and stirring the component (B), the component (C), and the component (D) in order in the obtained solution, each chromium-free metal surface of Examples 1 to 17, 24 to 33, and Comparative Examples 1 to 14 was obtained. A treating agent was obtained.

[Examples 18 to 23]
The type and amount (unit: g) of the component (A) shown in Table 1 were mixed with 100 g of ion-exchanged water, and the pH was adjusted to 6 with acetic acid. The component (B), the component (C), and the component (D) were sequentially mixed and stirred into the obtained solution. Furthermore, each chromium-free metal surface treating agent of Examples 18 to 23 was obtained by adjusting the pH to the one shown in Table 1 using acetic acid or 25% by mass aqueous ammonia.

The abbreviations in Tables 1 and 2 are as follows.
(Polysilyl-functional silane)
A1: 1,2-bis (triethoxysilyl) ethane ("KBE-3026", manufactured by Shin-Etsu Chemical Co., Ltd.)
A2: Vinyl trimethoxysilane ("KBM-1003" manufactured by Shin-Etsu Chemical Co., Ltd.)

(Silane coupling agent)
B1: 3-Aminopropyltriethoxysilane (“KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd.)
B2: 3-Aminopropyltrimethoxysilane ("KBM-903" manufactured by Shin-Etsu Chemical Co., Ltd.)
B3: N-2- (aminoethyl) -3-aminopropyltrimethoxysilane ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.)
B4: N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane ("KBM-602" manufactured by Shin-Etsu Chemical Co., Ltd.)
B5: Vinyltrimethoxysilane ("KBM-1003" manufactured by Shin-Etsu Chemical Co., Ltd.)
B6: 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.)

(Inorganic compound)
C1: Zirconium compound particles (“ZSL-20N”, manufactured by Daiichi Rare Element Chemical Co., Ltd., particle size: 60 to 105 nm, solid content concentration: 20% by mass)
C2: titanium compound particles (Sakai Chemical Industry Co., Ltd., “CSB-M”, particle size: 7 nm, solid content concentration: 30% by mass)
C3: zirconium compound particles (“EP zirconium oxide” manufactured by Daiichi Rare Element Chemical Co., Ltd., average particle size: 1.5 to 2.5 μm, solid content concentration: 100% by mass)
C4: Zirconium compound (Daiichi Rare Element Chemical Co., Ltd., “Zircosol AC-7”, solid content concentration: 20% by mass)
C5: silica particles (manufactured by ADEKA Corporation, "Adelite AT-20A", particle size: 10 to 20 nm, solid content concentration: 20% by mass)

(resin)
D1: Water-based cationic urethane resin (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “F-2667D”, solid content concentration: 25% by mass)
D2: water-based cationic urethane resin (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Superflex 650”, solid content concentration: 26% by mass)
D3: water-based cationic acrylic resin (“UW-550CS”, manufactured by Taisei Fine Chemical Co., Ltd., solid content concentration: 34% by mass)
D4: water-based anionic urethane resin (manufactured by ADEKA Corporation, “HUX-320”, solid content concentration: 32% by mass)
D5: aqueous nonionic urethane resin (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Superflex 500M”, solid content concentration: 45% by mass)
D6: Water-based anionic acrylic resin (manufactured by Seiden Chemical Co., Ltd., "AD-7", solid content concentration: 39% by mass)

<Evaluation>
Using the chromium-free metal surface treatment agents of Examples 1 to 33 and Comparative Examples 1 to 14, the corrosion resistance, adhesion, chemical resistance, and storage stability were evaluated as follows. The results are shown in Tables 3 and 4.

[Preparation of test plate]
The steel sheets shown in Tables 3 and 4 were degreased by spraying at 60 ° C. for 1 minute using an alkaline degreaser (“Surf Cleaner 155” manufactured by Nippon Paint Surf Chemicals Co., Ltd.). The degreased steel sheet was washed with water and then dried. Next, the chromium-free metal surface treatment agents of Examples 1 to 33 and Comparative Examples 1 to 14 were applied to the surface of the steel sheet using a bar coater so that the amount of the coating film becomes the value shown in Tables 1 and 2. Was baked and dried until the temperature reached 90 ° C. Next, a chrome-free primer coating and a top coating (both manufactured by Nippon Paint Industrial Coatings Co., Ltd.) were applied, respectively, to obtain a coated steel sheet.

[Evaluation of corrosion resistance]
A 5 w / v% saline solution at 35 ° C was sprayed on the painted surface of the painted steel plate. After 1000 hours from the spraying of the saline solution, the corrosion resistance was evaluated by visually checking the ratio (%) of the area where white rust was generated. The evaluation was performed on both the flat portion and the bent portion where the bending process (2T process) was performed with two plates interposed therebetween.
The evaluation criteria are as follows. A pass was given if the evaluation criteria were 3 or more.
-Evaluation criteria-
4 points: No white rust occurred 3 points: The area where white rust was generated was less than 10% 2 points: The area where white rust was generated was 10% or more and less than 30% 1 point: White rust was generated Area is 30% or more

[Evaluation of adhesion]
The coated steel plate was subjected to a 180 ° bending process (0T process). Then, after applying a tape to the painted surface of the bent portion, the tape was peeled off, and the adherence was evaluated by visually checking the percentage (%) of the area where the paint was peeled off.
The evaluation criteria are as follows. A score of 3 or more on this evaluation standard was considered a pass.
-Evaluation criteria-
4 points: No peeling 3 points: Peeled area is less than 25% 2 points: Peeled area is 26% or more and less than 50% 1 point: Peeled area is 50% or more

[Evaluation of chemical resistance]
a) Evaluation of Acid Resistance The coated steel sheet was immersed in a 5% w / v sulfuric acid aqueous solution at 25 ° C. for 24 hours, and the acid resistance was determined by visually checking the area (%) of the area where the coating film swelled. evaluated.
The evaluation criteria are as follows. A pass was given if the evaluation criteria were 3 or more.
-Evaluation criteria-
4 points: no swelling 3 points: swelling area is less than 25% 2 points: swelling area is 25% or more and less than 50% 1 point: swelling area is 50% or more

b) Evaluation of alkali resistance The coated steel sheet was immersed in a 5% w / v% sodium hydroxide aqueous solution at 25 ° C. for 24 hours, and the area (%) of the area where the coating film swelled was visually checked to determine the resistance. The alkalinity was evaluated.
The evaluation criteria are as follows. A pass was given if the evaluation criteria were 3 or more.
-Evaluation criteria-
4 points: no swelling 3 points: swelling area is less than 25% 2 points: swelling area is 25% or more and less than 50% 1 point: swelling area is 50% or more

[Evaluation of storage stability]
Storage stability by storing the chromium-free metal surface treatment agents of Examples 1 to 33 and Comparative Examples 1 to 14 in a thermostat at 40 ° C for 3 months and visually observing the state of gelation and precipitation. Was evaluated.
The evaluation criteria are as follows. A pass was given when the evaluation criteria were 2 points.
-Evaluation criteria-
2 points: No gelation or precipitation is observed 1 point: Gelation or precipitation is observed

The abbreviations in Tables 3 and 4 are as follows.
(steel sheet)
GL: Aluminum zinc alloy plated steel sheet (Al: 55% by mass)
GI: Hot dip galvanized steel sheet GF: Aluminum zinc alloy coated steel sheet (Al: 5% by mass)
EG: Electrogalvanized steel sheet SUS: Stainless steel sheet AL: Aluminum sheet

  As shown in Tables 3 and 4, selected from (A) polysilyl functional silane, (B) amino group-containing silane coupling agent, (C) inorganic compound particles, and (D) aqueous cationic urethane resin and aqueous cationic acrylic resin. Chromium-free containing at least one of the following components, and having a mass ratio (silicon solids / silicon) of silicon in the components (A) and (B) to resin solids in the component (D) of 1 to 5: Examples 1 to 33 using the metal surface treating agent were excellent in all of corrosion resistance, adhesion, chemical resistance, and storage stability. On the other hand, in Comparative Examples 1 to 14 using a chromium-free metal surface treatment agent that does not satisfy some requirements, at least one of the evaluations of corrosion resistance, adhesion, chemical resistance, and storage stability was performed in Example 1. ~ 33.

Claims (8)

The following components (A), (B), (C) and (D);
(A) a polysilyl functional silane (B) an amino group-containing silane coupling agent (C) an inorganic compound particle (D) containing at least one resin selected from an aqueous cationic urethane resin and an aqueous cationic acrylic resin,
A chromium-free metal surface treatment agent having a mass ratio (silicon solids / silicon) of silicon in the components (A) and (B) to resin solids in the component (D) in the range of 1 to 5.   The chromium-free metal surface treating agent according to claim 1, wherein a mass ratio of the component (A) to the component (B) (the component (A) / the component (B)) is in a range of 0.2 to 8.7. .   The chromium-free metal surface treatment agent according to claim 1 or 2, wherein the component (A) is 1,2-bis (triethoxysilyl) ethane.   The component (B) comprises 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- (aminoethyl)- The chromium-free metal surface treatment agent according to any one of claims 1 to 3, which is at least one member selected from the group consisting of 3-aminopropylmethyldimethoxysilane.   The chromium-free metal surface treatment agent according to any one of claims 1 to 4, wherein the component (C) is at least one selected from zirconium compound particles and titanium compound particles.   The chromium-free metal surface treatment agent according to any one of claims 1 to 5, wherein the average particle size of the component (C) is 1 µm or less. A step of applying the chromium-free metal surface treatment agent according to any one of claims 1 to 6 to the surface of a metal substrate,
Drying the chromium-free metal surface treatment agent applied to the metal substrate to form a film,
A metal surface treatment method comprising:   A metal substrate having a coating of the chromium-free metal surface treatment agent according to claim 1.