Aqueous chromium-free surface treatment agent, surface-treated metal, and surface treatment method

Abstract

This invention provides an aqueous chromium-free metal surface treatment agent capable of forming a high-strength, processable film on a metal substrate. The aqueous chromium-free surface treatment agent comprises a bifunctional silane compound (A), a monofunctional silane compound (B), and an alkynyldiol-based surfactant (C). Preferably, the concentration of the bifunctional silane compound (A) is in the range of 1–100 g / L, the concentration of the monofunctional silane compound (B) is in the range of 1–100 g / L, and the concentration ratio (A / B) of the bifunctional silane compound (A) to the monofunctional silane compound (B) is in the range of 0.1–5.

Description

Technical Field

[0001] This invention relates to water-based chromium-free surface treatment agents, surface-treated metals, and surface treatment methods. Background Technology

[0002] Previously, chromium-based metal surface treatment agents, such as chromate treatment agents and chromate phosphate treatment agents, were known as surface treatment agents for imparting corrosion resistance to metal substrates and are still widely used. However, given recent trends in environmental restrictions, the use of chromium-based metal surface treatment agents may be limited in the future due to the toxicity of chromium, particularly its carcinogenicity.

[0003] Therefore, various chromium-free metal surface treatment agents exhibiting corrosion resistance equivalent to chromium-based metal surface treatment agents have been developed. For example, Patent Document 1 discloses a composition for metal surface treatment containing a condensation reaction product of titanium compounds and / or zirconium compounds, aminosilanes, and polysilyl functional group silanes.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-068930 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] When forming a film on a metal substrate using a chromium-free metal surface treatment agent, such as when the metal substrate is used for pre-coating metal, the formed film requires not only corrosion resistance but also coating adhesion that can withstand high-intensity processing. However, the coating adhesion of conventional chromium-free metal surface treatment agents when subjected to high-intensity processing on surface-treated metal substrates is not satisfactory and has room for improvement. For example, the treatment agent described in Patent Document 1, which uses a silane coupling agent as its main component, causes paint shrinkage and cracking during coating when the metal substrate has a smooth surface, thus failing to form a uniform film on the metal surface and resulting in insufficient coating adhesion.

[0009] The present invention was made in view of the above circumstances, and its object is to provide an aqueous chromium-free metal surface treatment agent capable of forming a processable film with high strength on a metal substrate.

[0010] Methods for solving problems

[0011] (1) The present invention relates to an aqueous chromium-free surface treatment agent comprising a bifunctional silane compound (A), a monofunctional silane compound (B) and an alkynyl diol surfactant (C).

[0012] (2) The water-based chromium-free surface treatment agent according to (1), wherein the concentration of the above-mentioned bifunctional silane compound (A) is in the range of 1 to 100 g / L, the concentration of the above-mentioned monofunctional silane compound (B) is in the range of 1 to 100 g / L, and the concentration ratio (A / B) of the above-mentioned bifunctional silane compound (A) to the above-mentioned monofunctional silane compound (B) is in the range of 0.1 to 5.

[0013] (3) The water-based chromium-free surface treatment agent according to (1) or (2), wherein the concentration of the above-mentioned acetylenol-based surfactant (C) is in the range of 0.05 to 1 g / L.

[0014] (4) The water-based chromium-free surface treatment agent according to any one of (1) to (3), wherein the contact angle on the surface of the mirror-finished aluminum plate is less than 25 degrees.

[0015] (5) The water-based chromium-free surface treatment agent according to any one of (1) to (4), wherein it further comprises water-dispersible metal oxide particles (D), the average particle size of the water-dispersible metal oxide particles (D) is less than 150 nm, and the concentration of the water-dispersible metal oxide particles (D) is in the range of 1 to 20 g / L.

[0016] (6) The water-based chromium-free surface treatment agent according to any one of (1) to (5), wherein it further comprises a polyurethane resin (E), wherein the polyurethane resin (E) is at least one of a polyurethane water-dispersible resin and a polyurethane water-soluble resin, and the concentration of the polyurethane resin (E) is in the range of 1 to 20 g / L.

[0017] (7) The water-based chromium-free surface treatment agent according to any one of (1) to (6), wherein it further comprises a capped isocyanate resin (F) and the concentration of the capped isocyanate resin (F) is in the range of 1 to 20 g / L.

[0018] (8) The water-based chromium-free surface treatment agent according to any one of (1) to (7) has a pH range of 5 to 7.

[0019] (9) A surface-treated metal formed by forming a surface-treated film on the surface using any one of (1) to (8).

[0020] (10) A surface treatment method comprising a surface treatment film forming step of forming a surface treatment film by treating the surface of a coated object with any one of (1) to (8) using an aqueous chromium-free surface treatment agent.

[0021] Invention Effects

[0022] According to the present invention, an aqueous chromium-free metal surface treatment agent is provided that can form a processable film on a metal substrate that can withstand high strength. Detailed Implementation

[0023] The following describes the water-based chromium-free surface treatment agent, surface-treated metal, and surface treatment method according to embodiments of the present invention. The present invention is not limited to the embodiments described below.

[0024] <Water-based Chromium-free Surface Treatment Agent>

[0025] The water-based chromium-free surface treatment agent of this embodiment comprises a bifunctional silane compound (A), a monofunctional silane compound (B), and an acetylenic diol surfactant (C). Additionally, it preferably comprises at least one of water-dispersible metal oxide particles (D), a polyurethane resin (E), and a capped isocyanate resin (F).

[0026] (Bifunctional silane compound (A))

[0027] A bifunctional silane compound (A) is a silyl compound having two silanol groups in one molecule or capable of being hydrolyzed to form silanol groups. Examples of bifunctional silane compounds (A) are those represented by the following formula (I).

[0028] [Chemistry 1]

[0029] (X 1 ) 3-a-b (R 1 ) a (R 2 ) b Si-Y-Si(R 3 ) c (R 4 ) d (X 2 ) 3-c-d …(I)

[0030] In the above formula (I), R 1 R 2 R 3 and R 4 Each of these groups independently represents a monovalent organic group having 1 to 30 hydrogen atoms or carbon atoms. Examples of such monovalent organic groups include hydrocarbon groups such as alkyl, alkenyl, cycloalkyl, and aryl groups, as well as hydrocarbon groups having functional groups such as hydroxyl, epoxy, and amino groups. Alkyl groups having 1 to 4 carbon atoms, such as methyl and ethyl groups, are preferred as monovalent organic groups.

[0031] In formula (I) above, Y represents a divalent organic group or an amine. Examples of divalent organic groups include alkylene, alkyleneoxy, alkylenethio, or groups containing the above-mentioned divalent organic groups as part of the structure. Alkylene is preferred as the above-mentioned divalent organic group. The number of carbon atoms in the above-mentioned divalent organic group is preferably 2 to 30, more preferably 2 to 12.

[0032] In the above formula (I), X 1 and X 2 Each can be independently represented by a hydrolyzable group. Examples of hydrolyzable groups include hydroxyl groups and alkoxy groups with 1 to 4 carbon atoms. X 1 and X 2 Preferably, it is hydroxyl-based. In X 1 and X 2 In the case of an alkoxy group, methoxy or ethoxy are preferred as the alkoxy group.

[0033] In equation (I) above, a and b each independently represent integers from 0 to 2, and 0 ≤ a + b ≤ 2. Additionally, c and d each independently represent integers from 0 to 2, and 0 ≤ c + d ≤ 2. Both a + b and c + d are preferably 0 or 1.

[0034] Specific examples of the bifunctional silane compound (A) shown in formula (I) above include bis(trimethoxysilyl)methane, 1,2-bis(trimethoxysilyl)ethane, 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, 1,9-bis(trimethoxysilyl)nonane, 1,9-bis(triethoxysilyl)nonane, bis(trimethoxysilyl)amine, bis(triethoxysilyl)amine, bis(trimethoxysilylmethyl)amine, bis(triethoxysilylmethyl)amine, bis(trimethoxysilylpropyl)amine, and bis(triethoxysilylpropyl)amine. From the perspectives of operational safety, corrosion resistance, and adhesion of the resulting film, 1,2-bis(triethoxysilyl)ethane is preferred.

[0035] Bifunctional silane compound (A) can be used alone or in combination with two or more. Furthermore, bifunctional silane compound (A) can be partially hydrolyzed or can be obtained through hydrolytic condensation.

[0036] The concentration of the bifunctional silane compound (A) in the water-based chromium-free metal surface treatment agent is preferably in the range of 1 to 100 g / L.

[0037] (Monofunctional silane compound (B))

[0038] Monofunctional silane compounds (B) are silane compounds having one silanol group in one molecule or being silanes that can be hydrolyzed to form a silanol group. Examples of monofunctional silane compounds (B) 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-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3- -Aminopropyltrimethoxysilane and other amino-containing silanes, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and other epoxy-containing silanes, trimethylsilanol, triethylsilanol and other monosilanol compounds, trimethylchlorosilane, triethylchlorosilane and other monochlorosilanes, trimethylmethoxysilane, trimethylethoxysilane and other monoalkoxysilanes, trimethylacetoxysilane and other monoacyloxysilanes, etc. Among these, amino-containing silanes are preferred, and 3-aminopropyltriethoxysilane is more preferred.

[0039] Monofunctional silane compounds (B) can be used alone or in combination of two or more. Furthermore, monofunctional silane compounds (B) can be partially hydrolyzed or can undergo hydrolytic condensation.

[0040] The concentration of the monofunctional silane compound (B) in the aqueous chromium-free metal surface treatment agent is preferably in the range of 1 to 100 g / L.

[0041] The concentration ratio (A / B) of the bifunctional silane compound (A) to the monofunctional silane compound (B) is preferably in the range of 0.1 to 5, more preferably in the range of 0.25 to 2.5. When the concentration ratio (A / B) exceeds 5, the number and strength of hydrogen bonds at the interface between the film and the coating decrease, thereby reducing the adhesion between the film and the coating. When the concentration ratio (A / B) is less than 0.1, the hydrophilicity of the film increases, which easily leads to water permeation, resulting in reduced corrosion resistance and coating adhesion after coating.

[0042] (Alkynediol surfactant (C))

[0043] The acetylenol-based surfactant (C) is a nonionic surfactant with an acetylene group. By including the acetylenol-based surfactant (C) together with a bifunctional silane compound (A) and a monofunctional silane compound (B) in an aqueous chromium-free metal surface treatment agent, the wettability of the aqueous chromium-free metal surface treatment agent on the metal substrate to which it is coated can be improved. For example, the contact angle with the metal substrate can be adjusted to 25 degrees or less. This allows a uniform coating film to be formed on the metal substrate. Examples of acetylenol-based surfactants (C) include, for example, compounds represented by the following formula (II).

[0044] [Chemistry 2]

[0045]

[0046] In equation (II) above, R 5 and R 6 Each can independently represent a hydrogen atom or a methyl group. In formula (II) above, R 7 and R 8 Each can be represented independently as a hydrogen atom or an alkylene group. Examples of alkylene groups include ethylene and propylene. That is, alkynyl glycol surfactants (C) can be either alkylene oxide addition-type or non-alkylene oxide addition-type.

[0047] In the above formula (II), n and m each independently represent integers from 1 to 10.

[0048] Commercially available products can be used as the acetylenol-based surfactant (C) shown in formula (II) above. Examples of commercially available products include Surfynol (Surfynol 104, Surfynol 465, etc.) manufactured by Nissin Chemical Industries, Ltd., and the OLFINE series manufactured by Air Products. The acetylenol-based surfactant (C) can be used alone or in combination with two or more.

[0049] The concentration of the acetylenic diol surfactant (C) in the aqueous chromium-free metal surface treatment agent is preferably in the range of 0.05 to 1 g / L, more preferably in the range of 0 to 0.5 g.

[0050] (Water-dispersible metal oxide particles (D))

[0051] The water-dispersible metal oxide particles (D) are water-dispersible metal oxide particles such as Zr oxide, Ti oxide, Si oxide, Al oxide, Ce oxide, Nb oxide, Nd oxide, Sn oxide, and La oxide. By including water-dispersible metal oxide particles (D) in the water-based chromium-free metal surface treatment agent, the brittle fracture of the formed film can be suppressed, and the coating adhesion that can withstand high-intensity processing can be further improved. Zr oxide is preferred as the water-dispersible metal oxide particle (D). One type of water-dispersible metal oxide particle (D) can be used alone, or two or more types can be used in combination.

[0052] The concentration of water-dispersible metal oxide particles (D) in the water-based chromium-free metal surface treatment agent is preferably in the range of 1 to 20 g / L, more preferably in the range of 2 to 15 g.

[0053] The average particle size (median particle size D50 determined by dynamic light scattering) of the water-dispersible metal oxide particles (D) is preferably 150 nm or less, more preferably 10 nm to 120 nm.

[0054] (Polyurethane-based resin (E))

[0055] The polyurethane resin (E) is at least one of a polyurethane-based water-dispersible resin and a polyurethane-based water-soluble resin. That is, the polyurethane resin (E) has either water solubility or water dispersibility. By including the polyurethane resin (E) in the water-based chromium-free metal surface treatment agent, the brittle fracture of the formed film can be suppressed, and the coating adhesion that can withstand high-strength processing can be further improved. There is no particular limitation on the polyurethane resin (E); for example, it can be obtained by polymerizing a polyol compound and a polyisocyanate compound using conventionally known methods. One type of polyurethane resin (E) can be used alone, or two or more types can be used in combination.

[0056] There are no particular limitations on the polyol compounds mentioned above, and conventionally known synthetic raw materials can be used. Examples include polyester polyols, polyesteramide polyols, polyether polyols, polysulfide polyols, polycarbonate polyols, polyacetal polyols, polyolefin polyols, and polysiloxane polyols.

[0057] There are no particular limitations on the polyisocyanate compounds mentioned above, and conventionally known synthetic raw materials can be used. For example, aliphatic isocyanates, alicyclic diisocyanates, aromatic diisocyanates, and aromatic aliphatic diisocyanates can be cited.

[0058] The concentration of polyurethane resin (E) in the water-based chromium-free metal surface treatment agent, calculated based on the resin solids content, is preferably in the range of 1 to 20 g / L, more preferably in the range of 5 to 15 g.

[0059] (End-capped isocyanate resin (F))

[0060] End-capped isocyanate resins (F) are water-soluble resins that react with polyurethane resins (E) to form a cross-linked structure. End-capped isocyanate resins (F) are condensation polymers of compounds (monomers) that have at least one end-capped isocyanate group in one molecule and are end-capped with end-capping agents such as phenolic, alcoholic, oxime, active methylene, amide, carbamate, and sulfite.

[0061] End-capped isocyanate resins (F) are obtained by adding an end-capping agent to a compound having at least one isocyanate group in one molecule. Examples of compounds having at least one isocyanate group in one molecule include aliphatic diisocyanates such as hexamethylene diisocyanate (including trimers), tetramethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate; and aromatic diisocyanates such as 4,4'-methylenebis(cyclohexyl isocyanate); 4,4'-diphenylmethane diisocyanate; toluene diisocyanate; and phenyl dimethyl diisocyanate. End-capped isocyanate resins (F) can be used alone or in combination of two or more.

[0062] The concentration of the water-based chromium-free metal surface treatment agent of the end-capped isocyanate resin (F), calculated based on the resin solids content, is preferably in the range of 1 to 20 g / L, more preferably in the range of 5 to 15 g.

[0063] (Other compounds)

[0064] In addition to the components described above, the water-based chromium-free metal surface treatment agent of this embodiment may also contain other components. Examples of other components include crosslinking agents other than those mentioned above that promote resin curing, surface conditioners for leveling purposes, and defoamers for foam suppression purposes.

[0065] (pH of water-based chromium-free metal surface treatment agent)

[0066] The aqueous chromium-free metal surface treatment agent of this embodiment preferably has a pH range of 5 to 7. By setting the pH of the aqueous chromium-free metal surface treatment agent to below 7, its storage stability is further improved.

[0067] (Contact angle of water-based chromium-free metal surface treatment agent)

[0068] The water-based chromium-free metal surface treatment agent of this embodiment has a contact angle of less than 25 degrees on the surface of a mirror-finished aluminum plate. Therefore, it exhibits good wettability to the metal substrate to be coated, enabling the formation of a uniform film. Consequently, coating adhesion is improved. The mirror-finished aluminum plate can be polished using ultrafine abrasive materials until the surface roughness Rz is 0.05–0.2 μm, and then washed with a degreasing agent (e.g., Surfcleaner 155 manufactured by NIPPON PAINTSURF CHEMICALS) and water. The contact angle can be the static contact angle value measured using a contact angle meter (e.g., KRUSS DSA20E) in a constant temperature chamber set to 20°C.

[0069] <Surface Treatment Methods>

[0070] The surface treatment method of this embodiment includes a surface treatment film forming step, in which a surface treatment film is formed by treating a metal substrate, which is the object to be coated, using the water-based chromium-free metal surface treatment agent described in this embodiment. The surface treatment film forming step includes, for example, a coating step of applying the water-based chromium-free metal surface treatment agent to the surface of the metal substrate, which is the object to be coated, and a drying step of drying the metal substrate coated with the water-based chromium-free metal surface treatment agent to form the film.

[0071] (Coating process)

[0072] In the coating process, there are no particular limitations on the method of applying water-based chromium-free metal surface treatment agent to the metal substrate. Examples include roller coating, brush coating, roller coating, bar coating, and flow coating.

[0073] (Drying process)

[0074] There are no particular limitations on the drying method used in the drying process; known methods can be used. The drying temperature in the drying process, based on the peak metal temperature reached on the surface of the metal substrate, is preferably 60–90°C.

[0075] The coating and drying processes can be performed simultaneously. For example, a water-based chromium-free metal surface treatment agent can be applied to a preheated metal substrate, and then dried using residual heat.

[0076] Regarding the film amount of the water-based chromium-free metal surface treatment agent in the surface treatment film formation process, the film amount after drying is preferably 0.1–500 mg / m³. 2 More preferably, it is within the range of 1–250 mg / m³. 2 Within the range.

[0077] The surface treatment method of this embodiment can further apply a primer or top coat to a metal substrate that has a film formed by the surface treatment film forming process.

[0078] <Surface-treated metals>

[0079] The surface-treated metal in this embodiment is formed by using the water-based chromium-free surface treatment agent described in this embodiment to form a surface treatment film on the surface of a metal substrate, which is the object to be coated. The metal substrate is not particularly limited and can include aluminum sheets, stainless steel sheets, galvanized steel sheets, galvanized alloy steel sheets, molten galvanized steel sheets, and other galvanized steel sheets. Alternatively, after forming the surface treatment film on the aforementioned metal substrate, lamination processing can be performed using a laminated film.

[0080] Examples of aluminum sheets include 3000 series aluminum alloys, 4000 series aluminum alloys, 5000 series aluminum alloys, 6000 series aluminum alloys, and aluminum-plated steel sheets produced by electroplating, melt plating, vapor plating, etc.

[0081] Examples of stainless steel sheets include SUS 300 series stainless steel and SUS 400 series stainless steel.

[0082] Examples of galvanized steel sheets include galvanized steel sheets, galvanized nickel steel sheets, galvanized iron steel sheets, galvanized chromium steel sheets, galvanized aluminum alloy steel sheets, galvanized titanium steel sheets, galvanized magnesium steel sheets, galvanized manganese steel sheets, and other galvanized electroplated, melt-plated, vapor-plated steel sheets, as well as galvanized or zinc-based alloy steel sheets.

[0083] As a laminated film, a resin film may be used, for example. Examples of resin films used include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polycarbonate (PC), triacetyl cellulose (TAC), polyvinyl chloride (PVC), polyester, polyolefin, polyphenylene sulfide (PPS), and acrylic thermoplastic resins. There are no particular limitations on the lamination process for stacking the above-mentioned laminated films; examples include dry lamination and extrusion lamination.

[0084] Example

[0085] The present invention will now be described in more detail based on embodiments, but the present invention is not limited to these embodiments.

[0086] <Preparation of Water-Based Chromium-Free Surface Treatment Agent>

[0087] [Example 1]

[0088] According to the concentrations listed in Table 1, components (A), (B), and (C) were mixed and stirred in ion-exchanged water to obtain the water-based chromium-free surface treatment agent of Example 1. As the bifunctional silane (A), pre-hydrolyzed 1,2-bis(triethoxysilyl)ethane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBE-3026") was used; as the monofunctional silane (B), 3-aminopropylethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBE-903") was used; and as the activator (C), Surfynol 104 (acetylenic diol surfactant, ethylene oxide addition type) manufactured by Air Products was used.

[0089] [Examples 2-21, Comparative Examples 1-5]

[0090] In Example 19, a pre-hydrolyzed bis(triethoxysilyl)amine (Dynasylan 1124, manufactured by EVONIC) was used as the bifunctional silane (A). In Example 20, 3-epoxypropoxytriethoxysilane (KBE-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the monofunctional silane (B). In Example 21, Surfynol 465 (acetylenic diol surfactant, ethylene oxide non-addition type), manufactured by Air Products, was used as the surfactant (C). In Comparative Example 4, Newcol 1000 (alkyl ether surfactant), manufactured by Nippon Emulsifier Co., Ltd., was used as the surfactant (C). In Comparative Example 5, a treatment agent containing hexavalent chromium (Surfcoat NRC 300, manufactured by NIPPON PAINT SURFCHEMICALS) was used instead of an aqueous chromium-free surface treatment agent. All other aspects were the same as in Example 1.

[0091] <Preparation of the Experimental Board>

[0092] Using the surface treatment agents of Examples 1-21 and Comparative Examples 1-5, surface treatment was performed on 3000 series and 5000 series aluminum plates (manufactured by Testpanel Corporation, Japan, with a plate thickness of 0.35 mm) as metal substrates, as shown in Table 1. The surface treatment was performed in the following order: After spray degreasing the aluminum plate with Surfcleaner 155 (manufactured by NIPPON PAINT SURFCHEMICALS Corporation) as an alkaline degreasing agent at 60°C for 10 seconds, it was spray-washed with water and dried. Then, the surface treatment agent was applied to the aluminum plate using a bar coater #3 and dried at PMT (peak metal temperature) of 80°C. In Comparative Example 5, the chromium adhesion amount after degreasing, washing, and drying was 30 mg / m³. 2The coating was applied using a bar coater and dried at PMT 60°C. On aluminum plates that had undergone surface treatment using the above method, a thermosetting acrylic clear coat (Nippon Paint Industrial Coatings, Superlack D1F R-37 Gold Matte AP) was applied to achieve a dry film thickness of 5 μm. The plates were then sintered and dried at PMT 250°C for 50 seconds to obtain the test panels of Examples 1-21 and Comparative Examples 1-5.

[0093] <Evaluation>

[0094] [Seamless fit after one bend]

[0095] Under 20°C conditions, the test plate was bent 180° without any spacer in the middle (0TT), or two 0.35mm aluminum plates were sandwiched in the middle and bent 180° (2TT). The tape was peeled off the bent section three times, and the degree of peeling was observed with a 20x magnifying glass. The results were evaluated according to the following criteria. A score of 4 or higher was considered acceptable. The results are shown in Table 1.

[0096] 5: No peeling; 4.5: 1-10% peeling; 4: 11-20% peeling; 3.5: 21-30% peeling; 3: 31-40% peeling; 2.5: 41-50% peeling; 2: 51-60% peeling; 1.5: 61-70% peeling; 1: 71-80% peeling; 0.5: 81-90% peeling; 0: 91-100% peeling.

[0097] [Second-time bending for a tight seal]

[0098] After immersing the test plate in boiling water for 2 hours, it was placed indoors for 24 hours. Similar to the test plate's single-bend tightness, the plate was evaluated under the same criteria at 0TT and 2TT conditions. A score of 3.5 or higher was considered acceptable. The results are shown in Table 1.

[0099] [Length of filamentous rust]

[0100] The cross-sectioned test plate was placed in a 2L beaker containing 50mL of concentrated hydrochloric acid. After being exposed to hydrochloric acid vapor for 10 minutes, it was placed in a constant temperature and humidity chamber at 40℃ and RT82%. After 250 hours, the length and number of fragments (number of filamentous rust pieces) of the rust starting from the cut were measured, and the total length of the filamentous rust was calculated. A length less than 2mm was considered acceptable. The results are shown in Table 1.

[0101] [SST (Saline Spray Test)]

[0102] The cross-sectioned test plate was immersed in a salt spray corrosion tester as shown in JIS Z2317 for 1000 hours. The average blister width of corrosion on one side starting from the cut and the average blister width of corrosion starting from the end face (upper burr edge, lower burr edge) were measured. A blister width of less than 1 mm was considered acceptable. The results are shown in Table 1.

[0103] [CCT (Combined Cyclic Corrosion Test)]

[0104] The cross-sectioned test plate was placed in a composite cyclic corrosion tester as shown in JIS K 5621 for 1000 hours. The average blister width of corrosion on one side starting from the cut and the average blister width of corrosion starting from the end face (upper burr, lower burr) were measured. A blister width of less than 1 mm was considered acceptable. The results are shown in Table 1.

[0105] [Contact Angle Measurement]

[0106] The surface treatment agents of Examples 1-21 and Comparative Examples 1-4 were used in an automatic contact angle meter (KRUSS DSA20E) to measure the static contact angle of the treatment agents dropped onto an aluminum plate in a constant temperature room at 20°C. The aluminum plate used was polished to a surface roughness Rz of 0.05-0.2 μm using an ultrafine particle polishing machine. The surface was then degreased with a degreasing agent (NIPPON PAINT SURF CHEMICALS Surfcleaner 155) at 60°C for 30 seconds, followed by rinsing with water. A contact angle below 25°C was considered acceptable. The results are shown in Table 1.

[0107] [Table 1]

[0108]

[0109] [Examples 22-38, Comparative Examples 6-9]

[0110] Further, metal oxide particles (D) of the types and amounts shown in Table 2 were added. In Comparative Example 9, a treatment agent containing hexavalent chromium (manufactured by NIPPON PAINT SURF CHEMICALS, Surfcoat NRC 300) was used instead of the water-based chromium-free surface treatment agent. Except as described above, the surface treatment agent was prepared in the same manner as in Example 1. The average particle size (D50) of the metal oxide particles (D) shown in Table 2 is as follows.

[0111] ZrO2: 80nm; TiO2: 10nm; SiO2: 9nm; CeO2: 15nm; Nb2O5: 4nm; SnO2: 2nm; Al2O3: 50nm.

[0112] <Preparation of the Experimental Board>

[0113] The galvanized 55wt% aluminum alloy steel sheet (GL) (manufactured by Testpanel Co., Ltd., Japan, sheet thickness 0.35mm) as the metal substrate was surface-treated in the same manner as in Example 1 and Comparative Example 5. An epoxy polyester primer (manufactured by Nippon Paint Industrial Coatings, NSC 5610NC PRIMER) was applied to the GL steel sheet that had undergone the surface treatment method described above using a bar coater to achieve a dry film thickness of 5μm. The sheet was then sintered and dried at PMT 215°C. Next, a polyester topcoat (manufactured by Nippon Paint Industrial Coatings, S / C 490HQ 1C4661) was applied to achieve a dry film thickness of 15μm using a bar coater. The sheet was then sintered and dried at PMT 230°C to obtain the test panels of Examples 22-38 and Comparative Examples 6-9.

[0114] <Evaluation>

[0115] [Seam tightness after 1 bend, seam tightness after 2 bends]

[0116] The tests were conducted following the same procedures as in Examples 1-21 and Comparative Examples 1-5, and the results were evaluated according to the following criteria. A score of 4 or higher was considered acceptable, and the results are shown in Table 2.

[0117] 5: No cracks; 4: Cracks on the entire surface of the machined part; 3: Peeling area is less than 20% of the machined part; 2: Peeling area is more than 20% and less than 80% of the machined part; 1: Peeling area is more than 80% of the machined part.

[0118] [SST (Salt Spray Test), CCT (Combined Cyclic Corrosion Test)]

[0119] The tests and evaluations were conducted following the same procedures as in Examples 1-21 and Comparative Examples 1-5. The corrosion resistance of the machined parts was further evaluated using the SST test. For the corrosion resistance of the machined parts, the percentage of white rust area on the coated surface after the SST test (2TT) was visually evaluated according to the following criteria.

[0120] 5: Rust-free; 4.5: 0–10%; 4: 11–20%; 3.5: 21–30%; 3: 31–40%; 2.5: 41–50%; 2: 51–60%; 1.5: 61–70%; 1: 71–80%; 0.5: 81–90%; 0: 91–100%.

[0121] The acceptance criteria for the SST and CCT tests shown in Table 2 are as follows: SST (corrosion resistance of machined parts): 4 or higher; SST (cutting parts): 1 or lower; SST (upper and lower end face): 7 or lower; CCT (cutting parts): 0.7 or lower; CCT (upper and lower end face): 3 or lower.

[0122] [Table 2]

[0123]

[0124] [Examples 39-56, Comparative Examples 10-13]

[0125] Except for the addition of metal oxide particles (D), polyurethane resin (E) (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., SUPERFLEX 650), and end-capped isocyanate resin (F) (manufactured by Lanxess Solutions Japan, Inc., Aqua BI220) of the types and amounts shown in Table 3, the preparation of the surface treatment agent and the fabrication of the test plates were carried out in the same manner as in Examples 22-38 and Comparative Examples 6-9.

[0126] [Table 3]

[0127]

[0128] <Evaluation>

[0129] Except that the conditions for the SST and CCT tests were changed from 1000hr to 1500hr, the evaluations were conducted under the same conditions as in Examples 22-38 and Comparative Examples 6-9. The results are shown in Table 4. It should be noted that the acceptance criteria for the SST and CCT tests shown in Table 4 are as follows: SST (corrosion resistance of machined parts): 3.5 or higher; SST (cut parts): 1.5 or lower; SST (upper and lower end faces): 6.1 or lower; CCT (cut parts): 0.7 or lower; CCT (upper and lower end faces): 3.5 or lower.

[0130] [Table 4]

[0131]

[0132] [Examples 57-74, Comparative Examples 14-17]

[0133] Further additions of the types and amounts of metal oxide particles (D), polyurethane resin (E), and end-capped isocyanate resin (F) shown in Table 5 were made. In Example 65, Al2O3 with an average particle size (D50) of 100 nm was used as the metal oxide particles (D). Otherwise, the surface treatment agent was prepared in the same manner as in Examples 22-38 and Comparative Examples 6-9. In the preparation of the test plates, the metal substrate was molten galvanized steel sheet (GI) (manufactured by Testpanel Co., Ltd., Japan, with a thickness of 0.35 mm). After spray washing, the plate was immersed in a nickel sulfate-based surface conditioner (NP conditioner 700, pH 3.0, 60°C) for 5 seconds. Otherwise, the plate was prepared according to the same steps as in Examples 22-38 and Comparative Examples 6-9.

[0134] [Table 5]

[0135]

[0136] <Evaluation>

[0137] [stability]

[0138] The liquid stability of the surface treatment solution after being prepared and left to stand in a constant temperature chamber at 40°C for 3 months was evaluated visually according to the following criteria: 1: No problem; 2: Slight turbidity.

[0139] Except as described above, the evaluation was conducted under the same conditions as in Examples 22-38 and Comparative Examples 6-9. The results are shown in Table 6. It should be noted that the acceptance criteria for the SST and CCT tests shown in Table 6 are as follows: SST (corrosion resistance of machined parts): 3.5 or higher; SST (cut parts): 6.0 or lower; SST (upper and lower end face): 6.1 or lower; CCT (cut parts): 0.7 or lower; CCT (upper and lower end face): 3.5 or lower.

[0140] [Table 6]

[0141]

[0142] [Examples 75-92, Comparative Examples 18-21]

[0143] Further, metal oxide particles (D), polyurethane resin (E), and end-capped isocyanate resin (F) of the types and amounts shown in Table 7 were added. In Example 83, Al2O3 with an average particle size (D50) of 140 nm was used as the metal oxide particles (D). The metal substrate was a stainless steel plate (304 in Table 7 represents SUS 304, and 430 represents SUS 430) (manufactured by Testpanel Corporation of Japan, with a plate thickness of 0.35 mm). Otherwise, the preparation of the surface treatment agent and the fabrication of the test plate were carried out in the same manner as in Examples 22-38 and Comparative Examples 6-9.

[0144] [Table 7]

[0145]

[0146] <Evaluation>

[0147] Except that the SST and CCT were set to 1500hr, the evaluation was conducted in the same manner as in Examples 57-74 and Comparative Examples 14-17. The results are shown in Table 8. It should be noted that the acceptance criteria for the SST and CCT tests shown in Table 8 are as follows: SST (corrosion resistance of machined parts): 4.0 or higher; SST (cut parts): 1.0 or lower; SST (upper and lower end face): 0.5 or lower; CCT (cut parts): 0 or lower; CCT (upper and lower end face): 0.5 or lower.

[0148] [Table 8]

[0149]

[0150] [Examples 93-112, Comparative Examples 22-25]

[0151] Except for the addition of metal oxide particles (D), polyurethane resin (E), and end-capped isocyanate resin (F) of the types and amounts shown in Table 9, the surface treatment agent was prepared in the same manner as in Examples 22-38 and Comparative Examples 6-9. In the preparation of the test plates, Surfcleaner 155 (manufactured by NIPPON PAINT SURF CHEMICALS) was used as an alkaline degreasing agent. The GI or GL plates shown in Table 9 (both manufactured by Testpanel, Japan, with a thickness of 0.35 mm) were spray-degreased at 60°C for 10 seconds, followed by spray washing. Then, they were immersed in a cobalt ion-based alkaline surface conditioner (NP conditioner 200, pH 11, 60°C) for 5 seconds, washed with water, and dried at PMT 80°C. Afterward, the treatment agent with the described components was applied to the GI or GL plates using a bar coater #3 and dried at PMT (peak metal temperature) 80°C. After surface treatment, a polyurethane adhesive was applied, and then an acrylic laminate (a 50 μm thick polypropylene film) was pressed onto it with a roller. The film was heated and bonded at 230°C to obtain the test panels of Examples 93-112 and Comparative Examples 22-25.

[0152] [Table 9]

[0153]

[0154] <Evaluation>

[0155] [One-time fit test (Erwin's cup test)]

[0156] A grid pattern was cut into the test plate using a cutting machine. After extrusion, the tape was peeled off to 8 mm using an Ellis cupping tester. The tape peel test was conducted according to JIS Z0237:2009. The degree of tape peel was evaluated according to the following criteria, with a score of 4 or higher considered acceptable. The results are shown in Table 10.

[0157] 5: No peeling; 4.5: 1-10% peeling; 4: 11-20% peeling; 3.5: 21-30% peeling; 3: 31-40% peeling; 2.5: 41-50% peeling; 2: 51-60% peeling; 1.5: 61-70% peeling; 1: 71-80% peeling; 0.5: 81-90% peeling; 0: 91-100% peeling

[0158] [Two tightness tests (Erwin's cup test)]

[0159] As a pre-processing step, a grid pattern was cut into the test plate using a cutting machine. After being extruded to 6 mm using an Ellis cupping tester, the plate was immersed in boiling water at 98°C for 1 hour, followed by tape peeling in the extrusion section. The degree of tape peeling was evaluated in the same manner as in the first adhesion test. The results are shown in Table 10.

[0160] In addition to the above, SST and CCT were evaluated at 1000hr. The results are shown in Table 10. It should be noted that the acceptance criteria for the SST and CCT tests shown in Table 10 are as follows: SST (cut section): 5.0 or less; SST (end face, top and bottom): 6.0 or less; CCT (cut section): 2 or less; CCT (end face, top and bottom): 3.5 or less.

[0161] [Table 10]

[0162]

[0163] The results of the above embodiments and comparative examples confirm that the water-based chromium-free metal surface treatment agent of the embodiments has excellent coating adhesion compared with the surface treatment agent of the comparative examples, and can form a film on the metal substrate that can withstand high strength processing.

Claims

1. An aqueous chromium-free surface treatment agent comprising a bifunctional silane compound (A), a monofunctional silane compound (B), and an acetylenic diol-based surfactant (C), wherein, The concentration of the acetylenic diol surfactant (C) is in the range of 0.05~0.4 g / L, and the concentration ratio of the bifunctional silane compound (A) to the monofunctional silane compound (B), i.e., A / B, is in the range of 0.1~5.

2. The water-based chromium-free surface treatment agent according to claim 1, wherein, The concentration of the bifunctional silane compound (A) is in the range of 1~100 g / L. The concentration of the monofunctional silane compound (B) is in the range of 1 to 100 g / L.

3. The water-based chromium-free surface treatment agent according to claim 1 or 2, wherein, The contact angle on the surface of the mirror-finished aluminum plate is less than 25 degrees.

4. The water-based chromium-free surface treatment agent according to claim 1 or 2, wherein, It further comprises water-dispersible metal oxide particles (D), the average particle size of which is less than 150 nm, and the concentration of which is in the range of 1 to 20 g / L.

5. The water-based chromium-free surface treatment agent according to claim 1 or 2, wherein, The product further comprises a polyurethane resin (E), wherein the polyurethane resin (E) is at least one of a polyurethane water-dispersible resin and a polyurethane water-soluble resin, and the concentration of the polyurethane resin (E) is in the range of 1 to 20 g / L.

6. The water-based chromium-free surface treatment agent according to claim 1 or 2, wherein, It further comprises a capped isocyanate resin (F), wherein the concentration of the capped isocyanate resin (F) is in the range of 1 to 20 g / L.

7. The water-based chromium-free surface treatment agent according to claim 1 or 2, wherein, pH range of 5 to 7.

8. A surface-treated metal, which is formed on the surface by using the water-based chromium-free surface treatment agent according to claim 1 or 2 to form a surface treatment film.

9. A surface treatment method comprising a surface treatment film forming step of forming a surface treatment film by treating the surface of a workpiece with the water-based chromium-free surface treatment agent according to claim 1 or 2.

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