Electrodeposition sealing agent, composite structure, metal fitting and product

Abstract

The invention provides an electro-deposition sealing agent, a composite structure, a metal accessory and a product. The sealing agent is prepared from the following materials: epoxy resin, a reactive diluent, a hole sealing agent, a photoinitiator, an auxiliary agent and a solvent. The photoinitiator comprises a cationic photoinitiator; the hole sealing agent comprises an inorganic nanometer material, and the particle size of the inorganic nanometer material is 5 nm to 20 nm. The electrodeposition sealing agent provided by the invention permeates and fills pores existing in a gold plating layer, improves the compactness of the gold plating layer, also improves the hydrophobicity of the surface of the gold plating layer, effectively prevents a corrosive medium from being attached and permeated on the surface of the gold plating layer, improves the protection capability of the gold plating layer, prolongs the service life of the gold plating layer, and improves the service life of the gold plating layer. And the metal texture of the gold plating layer is not affected, and the excellent protection effect and decoration performance are achieved. The electro-deposition sealing agent provided by the invention is easy to construct and can be widely applied to surface treatment of metal products in the field of kitchens and baths.

Description

Technical Field

[0001] This application relates to the field of electroplating technology, and in particular to electrodeposition sealing agents, composite structures, metal fittings and products. Background Technology

[0002] As people's living standards continue to improve, traditional electroplating surface treatments can no longer meet their functional needs for products. Gold plating has a golden luster, an attractive appearance, and can enhance the decorative properties of products. Furthermore, gold is chemically stable and not easily corroded in environments such as the atmosphere, water, and most acids and alkalis. Therefore, gold plating can effectively improve the corrosion resistance of products and extend their service life. However, because electroplated gold layers are usually thin, nanoscale pores can easily form on the surface of the gold plating during the preparation process, leading to the penetration of corrosive media and causing plating corrosion, resulting in "white rust." This not only affects the appearance but also significantly reduces its protective performance and shortens the service life of the gold plating. Summary of the Invention

[0003] Therefore, it is necessary to provide an electrodeposition sealant that, when applied to a gold plating layer, can fill the pores and defects of the gold plating layer, significantly improve the density of the gold plating layer, reduce the permeability of corrosive media in the gold plating layer, thereby improving the corrosion resistance and service life of the gold plating layer, while also ensuring that the gold plating layer has a good decorative effect.

[0004] In a first aspect, this application provides an electrodeposition sealing agent, the materials for preparing the electrodeposition sealing agent including epoxy resin, reactive diluent, sealing agent, photoinitiator, additives and solvent;

[0005] The photoinitiator includes a cationic photoinitiator;

[0006] The sealing agent comprises inorganic nanomaterials with a particle size of 5nm-20nm.

[0007] Optionally, the materials used to prepare the electrodeposition sealing agent, by weight percentage, include:

[0008] Epoxy resin 30%-40%,

[0009] 10%-20% reactive diluent

[0010] Sealing agent 2%-5%,

[0011] Photoinitiator 3%-5%,

[0012] Additives 2%-10%, and

[0013] Solvent 30%-45%.

[0014] Optionally, the material used to prepare the electrodeposition sealing agent also satisfies at least one of the following characteristics (1) to (8):

[0015] (1) The epoxy equivalent of the epoxy resin is 160 g / eq-230 g / eq;

[0016] (2) The solid content of the epoxy resin is 95%-100% by mass;

[0017] (3) The average molecular weight of the epoxy resin is 360 g / mol-488 g / mol;

[0018] (4) The active diluent includes one or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, propenyl glycidyl ether, p-cresol glycidyl ether, glycidyl methacrylate, diglycidyl ether, ethylene glycol diglycidyl ether and resorcinol diglycidyl ether;

[0019] (5) The inorganic nanomaterials include one or more of nano-silicon-based oxides, nano-aluminum-based oxides, and nano-titanium-based oxides;

[0020] (6) The cationic photoinitiator includes one or more of iodonium salt photoinitiators and thionium salt photoinitiators;

[0021] (7) The additives include one or more of leveling agents and antioxidants;

[0022] Optionally, the leveling agent includes a silicone leveling agent;

[0023] Further optionally, the silicone leveling agent includes one or more of dimethylsiloxane, polyether-modified silicone, and polyester-modified silicone;

[0024] Optionally, the antioxidant includes hindered phenolic antioxidants;

[0025] (8) The solvent includes organic solvents;

[0026] Optionally, the organic solvent includes one or more of ethanol, acetone, N,N-dimethylformamide and N,N-dimethylacetamide.

[0027] Secondly, this application provides a method for preparing an electrodeposition sealing agent, comprising the following steps:

[0028] While the epoxy resin is being stirred, a photoinitiator, an active diluent, and a solvent are added and mixed to form a first dispersion.

[0029] Add an auxiliary agent to the first dispersion and mix to form a second dispersion;

[0030] Add a sealing agent to the second dispersion and mix to form an electrodeposition sealing agent.

[0031] Thirdly, this application also provides a composite structure, including a metal substrate and a nickel plating layer, a gold plating layer and a sealant layer sequentially stacked on the surface of the metal substrate;

[0032] The sealing layer is obtained by treating an electrodeposited sealing agent prepared by the method of preparing the electrodeposited sealing agent provided in the first aspect or the electrodeposited sealing agent provided in the second aspect.

[0033] Optionally, the composite structure also satisfies at least one of the features shown in (1) to (4) below:

[0034] (1) The metal substrate includes one or more of copper alloy, zinc alloy and stainless steel;

[0035] (2) The thickness of the nickel plating is 15μm-20μm;

[0036] (3) The nickel plating layer includes a semi-bright nickel layer and / or a fully bright nickel layer;

[0037] Optionally, the thickness of the semi-bright nickel layer is 5μm-7μm;

[0038] Optionally, the thickness of the all-bright nickel layer is 10μm-13μm;

[0039] Optionally, in the composite structure, the semi-bright nickel layer and the fully bright nickel layer are sequentially disposed on the surface of the metal substrate;

[0040] (4) The thickness of the gold plating layer is 0.3μm-0.4μm.

[0041] Optionally, the composite structure further includes a passivation layer disposed between the gold plating layer and the sealant layer;

[0042] Optionally, the passivation layer includes a potassium dichromate passivation layer and / or a chromic anhydride passivation layer;

[0043] Optionally, the thickness of the passivation layer is 200nm-500nm.

[0044] Fourthly, this application also provides a method for preparing a composite structure, comprising the following steps:

[0045] Prepare the metal substrate;

[0046] A first structure is prepared by placing a metal substrate in a nickel plating solution and forming a nickel plating layer on the surface of the metal substrate.

[0047] The first structure is placed in a gold plating solution for treatment, and a gold plating layer is formed on the surface of the first structure to prepare the second structure;

[0048] The second structure is placed in an electrodeposition sealing agent solution for treatment, and then photocured to form a sealing agent layer on the surface of the second structure, thereby preparing the composite structure provided in the third aspect;

[0049] Optionally, before the second structure is treated with an electrodeposition sealing agent, the second structure is placed in a passivation solution to form a passivation layer on the surface of the second structure.

[0050] Optionally, the preparation method also satisfies at least one of the following (1) to (4):

[0051] (1) The process of treating the second structure in the electrodeposition sealing agent includes: treating the second structure in the electrodeposition sealing agent for 2 min-5 min, and then taking out the second structure for cleaning;

[0052] (2) The electrodeposition sealing agent solution is an electrodeposition sealing agent solution diluted with water to a concentration of 1%-5%;

[0053] (3) Ultraviolet light is used for photocuring;

[0054] Optionally, the wavelength of the ultraviolet light is 200nm-400nm;

[0055] Optionally, the intensity of the ultraviolet light is 1500 mW / cm². 2 -3000 mW / cm 2 ;

[0056] (4) The curing time is 30s-120s.

[0057] Fifthly, this application also provides a metal fitting, which includes the composite structure provided in the third aspect, or the composite structure prepared by the method for preparing the composite structure provided in the fourth aspect.

[0058] Compared with traditional technologies, the beneficial effects of the technical solution in this application include:

[0059] This application provides an electrodeposition sealant. The materials used to prepare the sealant include epoxy resin, reactive diluent, sealing agent, photoinitiator, additives, and solvent. The photoinitiator includes a cationic photoinitiator. The sealing agent comprises inorganic nanomaterials with a particle size of 5 nm-20 nm. The electrodeposition sealant provided by this application can penetrate and fill pores and defects in the gold plating structure, significantly reducing the porosity of the gold plating structure and improving its density. It also greatly enhances the hydrophobicity of the gold plating surface, effectively preventing the adhesion of corrosive media to the surface, thereby significantly reducing the penetration of corrosive media and improving the protective capability of the gold plating and the overall plating structure, while maintaining the metallic texture of the gold plating. Furthermore, the electrodeposition sealant provided by this application has excellent adhesion to the gold plating, increasing the protection time of the gold plating and extending the service life of the workpiece. The electrodeposition sealant provided by this application is easy to apply and can be widely used in the surface treatment of metal products in the kitchen and bathroom industry. Attached Figure Description

[0060] Figure 1 This is a SEM image of the composite structure surface sealant layer prepared in Example 5 of this application.

[0061] Figure 2 This is a SEM image of the composite structure surface sealing agent layer prepared in Comparative Example 1 of this application. Detailed Implementation

[0062] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0064] As used herein, "optional," "optional," and "optional" refer to either "with" or "without" parallel options. If multiple "optional" entries appear in a technical solution, each "optional" entry is independent unless otherwise specified and there are no contradictions or mutual constraints. The term "and / or" as used herein includes any and all combinations of one or more related listed items. Unless otherwise specified, "multiple," "multiple," etc., as used herein refer to a quantity greater than 2 or equal to 2; for example, "one or more" indicates one, two, or more than two. In open-ended technical features or solutions described herein using words such as "containing," "including," and "comprising," unless otherwise specified, additional members beyond the listed members are not excluded. This can be considered as providing both a closed-ended feature or solution consisting of the listed members and an open-ended feature or solution that includes additional members beyond the listed members.

[0065] In this application, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0066] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0067] While gold (Au) possesses excellent appearance, luster, and chemical stability, and is not easily corroded by air, water, or most acidic and alkaline environments, gold plating in electroplating processes is typically thin. This leads to the formation of nanoscale pores on the surface of the gold plating during preparation, allowing corrosive media to penetrate. Consequently, in certain environments, such as humid conditions or atmospheres containing corrosive gases, gold plating may still corrode or discolor, resulting in "white rust," which not only affects its appearance but also significantly reduces its protective performance and lifespan. Furthermore, as corrosive media penetrate through the pores and defects on the gold plating surface into the intermediate plating layer, they further corrode the intermediate layer, causing deep corrosion of the overall plating structure and significantly reducing its protective effect. Simultaneously, as corrosive media penetrate to the intermediate plating layer, a closed loop is formed between the gold plating layer and the intermediate plating layer in the electrolyte environment created by the corrosive media. The potential difference between the nickel plating layer and the gold plating layer satisfies the conditions for a galvanic cell reaction, thus triggering a micro-cell reaction. The micro-battery reaction causes the intermediate plating layer to gradually corrode and dissolve, reducing its thickness and significantly diminishing its protective effect on the base metal. As the intermediate plating layer corrodes, the gold plating may peel or flake due to the loss of underlying support, affecting its integrity and aesthetics, and also reducing the overall protective performance of the plating structure. Furthermore, as the intermediate plating layer corrodes, the base loses effective protection and becomes more susceptible to direct contact with corrosive media, leading to further corrosion. This results in a significant decrease in base properties such as strength and toughness, potentially impacting the lifespan and safety of the entire workpiece. In addition, as corrosion deepens, metal ions generated after corrosion can enter the surrounding environment, potentially polluting soil and water bodies and negatively impacting the ecosystem if left untreated. Moreover, damage to the gold plating layer can lead to the loss of precious gold, resulting in resource waste.

[0068] Traditional and inorganic sealants both have some problems. Inorganic sealants, in particular, form protective films that are prone to cracking and lack elasticity. Traditional sealants also have poor salt spray resistance; after passivation and sealant treatment, they are insufficient to provide effective protection for approximately 72 hours, making it difficult to meet further corrosion resistance requirements. Furthermore, after drying, traditional sealants can reduce the gloss of original metallic coatings, such as gold plating, resulting in a lack of metallic sheen and diminishing the decorative effect.

[0069] To overcome the problems of inorganic sealants causing the protective film to crack easily and lacking elasticity, and the fact that traditional sealants, after drying, result in a decrease in gloss compared to the original metallic coating, making the product lack a metallic feel and reducing its decorative effect, this application aims to provide an electrodeposition sealant to treat the surface of a gold plating layer, thereby improving the overall protective performance of the plating structure and enabling it to meet people's functional requirements for the product.

[0070] In a first aspect, this application provides an electrodeposition sealing agent, the materials for preparing the electrodeposition sealing agent including epoxy resin, reactive diluent, sealing agent, photoinitiator, additives and solvent;

[0071] The photoinitiator includes a cationic photoinitiator;

[0072] The sealing agent comprises inorganic nanomaterials with a particle size of 5nm-20nm.

[0073] The materials used in this application for preparing the electrodeposition sealing agent include epoxy resin, reactive diluent, sealing agent, additives, and solvent. Epoxy resin, as the main film-forming substance, provides good chemical corrosion resistance. However, epoxy resin has a high viscosity, resulting in poor flowability and permeability of the prepared electrodeposition sealing agent system. Therefore, this application reduces the viscosity of the epoxy resin and improves the adhesion between the electrodeposition sealing agent and the plating layer by adding a reactive diluent. This improves the flowability and permeability of the sealing agent system, making it easier to coat onto the electroplated surface. It also provides better dispersibility for the sealing agent, allowing it to better penetrate and fill the pores and defects in the gold plating layer, increasing the sealing agent layer formed on the gold plating surface, and improving the hardness, wear resistance, and corrosion resistance of the gold plating layer. The sealing agent in this application uses inorganic nanomaterials with a particle size of 5nm-20nm. On the one hand, the inorganic nanomaterials significantly reduce the hydrophobicity of the sealing agent layer. On the other hand, within this particle size range, it better fills the nanoscale pores of the gold plating layer, achieving a denser gold plating structure. This application utilizes a photoinitiator to achieve a sealing layer formed by photocuring the electrodeposited sealing agent during the treatment process. This improves the hardness, wear resistance, and corrosion resistance of the gold plating. Furthermore, the cationic photoinitiator enhances the hydrophobicity of the sealing layer, reducing the adhesion of corrosive media to the gold plating surface and further preventing penetration, thus improving the protective performance of the gold plating. The electrodeposited sealing agent provided in this application maintains a smooth and even surface on the gold plating, preserving its metallic texture and meeting functional requirements for the product.

[0074] In some embodiments, the inorganic nanomaterials, with a particle size range of 5 nm to 20 nm, can better penetrate and fill the nanoscale pores in the gold plating structure, thereby improving the density and corrosion resistance of the gold plating. As a non-limiting example, the particle size of the inorganic nanomaterials includes, but is not limited to, 5 nm, 8 nm, 10 nm, 12 nm, 14 nm, 15 nm, 18 nm, 20 nm, or any combination thereof, and values ​​within that range.

[0075] In some embodiments, the materials used to prepare the electrodeposition sealing agent, by weight percentage, include:

[0076] Epoxy resin 30%-40%,

[0077] 10%-20% reactive diluent

[0078] Sealing agent 2%-5%,

[0079] Photoinitiator 3%-5%,

[0080] Additives 2%-10%, and

[0081] Solvent 30%-45%.

[0082] The materials for preparing electrodeposition sealing agents with the specific composition range provided in this application can better achieve compatibility, dispersibility, and flowability among the components, thus achieving good compatibility and better surface treatment of gold plating. While improving the surface protection effect of gold plating, it also ensures the gloss of gold plating.

[0083] The specific epoxy resin used in this application has a certain impact on the treatment effect of the electrodeposition sealing agent. Factors such as the epoxy equivalent and solid content of the epoxy resin may affect the viscosity, film-forming properties, and curing performance of the sealing agent system. In some embodiments, the epoxy equivalent of the epoxy resin is 160 g / eq-230 g / eq. Within this range, the sealing agent system can be provided with suitable viscosity, flowability, and curing characteristics. In some embodiments, the solid content of the epoxy resin is 95%-100%. Within this range, the epoxy resin has suitable viscosity and flowability, making it easier to handle during application and providing suitable flowability and penetration for the electrodeposition sealing agent of this application during application. In some embodiments, the average molecular weight of the epoxy resin is 360 g / mol-488 g / mol. Within this range, the epoxy resin has suitable flowability and film-forming properties, and after curing, a sealing agent layer with a suitable crosslinking density can be obtained. As a non-limiting example, the epoxy resins used in this application include, but are not limited to, bisphenol A type epoxy resin and / or bisphenol F type epoxy resin, which can better achieve the technical effects of this application. The type of bisphenol A epoxy resin includes one or more of E-51 and E-44.

[0084] The reactive diluent used in the electrodeposition sealant of this application has a certain influence on the flowability and mechanical properties of the sealant system. In some embodiments, the reactive diluent includes one or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, propylene glycidyl ether, p-cresol glycidyl ether, glycidyl methacrylate, diglycidyl ether, ethylene glycol diglycidyl ether, and resorcinol diglycidyl ether. On the one hand, the reactive diluent can adjust the viscosity, flowability, and permeability of the sealant system, improving the dispersibility and film uniformity of epoxy resin, sealing agent, etc. in the sealant system. On the other hand, the reactive diluent component has a specific functional group structure, which can form a specific cross-linking structure during photocuring, improving the density and hydrophobic effect of the sealant layer itself. Furthermore, the reactive diluent can also improve the bonding force between the electrodeposition sealant and the gold plating layer, improving adhesion and the mechanical properties of the gold plating layer, thereby extending the corrosion resistance time of the sealant layer. Furthermore, the use of one or more reactive diluents selected from butyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether can better achieve the technical effects of this application.

[0085] In some embodiments, the inorganic nanomaterials added to the materials used to prepare the electrodeposition sealing agent according to this application include one or more of nano-silicon-based oxides, nano-aluminum-based oxides, and nano-titanium-based oxides. As a non-limiting example, the inorganic nanomaterials include one or more of nano-silica, nano-alumina, and nano-titanium dioxide.

[0086] In some embodiments, the cationic photoinitiator includes one or more of iodonium salt photoinitiators and / or thiodonium salt photoinitiators. The use of a cationic photoinitiator in this application can significantly improve the hydrophobicity of the sealing layer after cross-linking and curing. By improving the hydrophobicity of the sealing layer, the adhesion of corrosive media to the gold plating surface is greatly reduced, thereby achieving a significant improvement in anti-corrosion performance. Furthermore, the use of iodonium salt photoinitiators and / or thiodonium salt photoinitiators in this application can better achieve the technical effects of this application. As a non-limiting example, the cationic photoinitiator is selected from one or more of triphenylthiodonium hexafluoroantimonate, triphenylthiodonium hexafluorophosphate, and diphenyliodonium hexafluorophosphate.

[0087] The materials used in this application for preparing the electrodeposition sealant also include additives to further enhance its performance. In some embodiments, the additives include one or more of leveling agents and antioxidants. Using leveling agents and defoamers in some embodiments can better improve the dispersion uniformity and application performance of the sealant system, ensuring a smooth and even gold plating surface after sealant treatment.

[0088] In some embodiments, the leveling agent comprises a silicone leveling agent. As a non-limiting example, the silicone leveling agent comprises one or more of dimethylsiloxane, polyether-modified silicone, and polyester-modified silicone. Furthermore, the use of dimethylsiloxane can better achieve the technical effects of this application.

[0089] In some embodiments, the antioxidant includes a hindered phenolic antioxidant, which can better improve the anti-aging properties of the electrodeposition sealant and extend the service life of the coating. As a non-limiting example, the hindered phenolic antioxidant includes one or more of Irganox 1076 and Irganox 1010.

[0090] In some embodiments, the solvent comprises an organic solvent. As a non-limiting example, the organic solvent includes one or more of ethanol, acetone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0091] The materials provided in this application for preparing electrodeposition sealing agents have good compatibility, dispersibility, and flowability among their components. When used for surface treatment of gold plating, they can fully penetrate into the pores of the gold plating structure to fill them, significantly improving the density and hydrophobicity of the gold plating. This effectively prevents the adhesion and penetration of corrosive media on the surface of the gold plating, greatly enhancing the corrosion resistance of the gold plating, extending the service life of the overall plating structure, and ensuring the gloss of the gold plating, thus meeting the multifunctional requirements of the product.

[0092] Secondly, this application also provides a method for preparing an electrodeposition sealing agent, comprising the following steps:

[0093] The electrodeposition sealing agent provided in the first aspect is prepared by mixing and stirring epoxy resin, reactive diluent, sealing agent, photoinitiator, additives and solvent.

[0094] The method for preparing the electrodeposition sealing agent of this application is simple and easy to operate. In some embodiments, the method for preparing the electrodeposition sealing agent includes:

[0095] S10. While the epoxy resin is being stirred, add the photoinitiator, reactive diluent, and solvent to form a first dispersion.

[0096] S11. Add an auxiliary agent to the first dispersion and mix to form a second dispersion;

[0097] S12. Add a sealing agent to the second dispersion and mix to form an electrodeposition sealing agent.

[0098] In some embodiments, the stirring speed of step S10, step S11 and / or step S12 is 150 rpm to 350 rpm.

[0099] The electrodeposition sealant provided in this application is simple to prepare and can fully achieve uniform dispersion of each component in the sealant system. The prepared sealant has good flowability and permeability.

[0100] Thirdly, this application also provides a composite structure, including a metal substrate and a nickel plating layer, a gold plating layer and a sealant layer sequentially stacked on the surface of the metal substrate;

[0101] The sealing layer is obtained by treating an electrodeposited sealing agent prepared by the method of preparing the electrodeposited sealing agent provided in the first aspect or the electrodeposited sealing agent provided in the second aspect.

[0102] The composite structure provided in this application is a multi-layered structure with excellent bonding and adhesion between the layers, achieving superior protection of the metal material through the overall coating structure. Furthermore, the electrodeposition sealant of this application is used to fill the gold plating surface to form a sealant layer, which greatly improves the density and surface hydrophobicity of the gold plating, thereby preventing the adhesion and penetration of corrosive media into the nickel plating. This effectively prevents the nickel plating from being corroded and dissolved by corrosive media, inhibits the micro-battery reaction formed between the nickel and gold plating layers, enhances the stability and protective capability of the overall coating structure, and extends the service life of the composite structure.

[0103] As a non-limiting example, the metal substrate includes one or more of copper alloys, zinc alloys, and stainless steel.

[0104] In some embodiments, the thickness of the gold plating is 0.3 μm to 0.4 μm. As a non-limiting example, it includes, but is not limited to, 0.3 μm, 0.31 μm, 0.32 μm, 0.33 μm, 0.34 μm, 0.35 μm, 0.36 μm, 0.37 μm, 0.38 μm, 0.39 μm, 0.4 μm, or any range formed by both of the foregoing and values ​​within that range.

[0105] In some embodiments, the thickness of the nickel plating is 15 μm-20 μm. As a non-limiting example, it includes, but is not limited to, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any combination thereof and values ​​within that range.

[0106] In some embodiments, the nickel plating includes a semi-bright nickel layer and / or a fully bright nickel layer.

[0107] In some embodiments, the thickness of the semi-bright nickel layer is 5 μm-7 μm. As a non-limiting example, it includes, but is not limited to, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm or any combination thereof and values ​​within that range.

[0108] In some embodiments, the thickness of the all-bright nickel layer is 10 μm-13 μm. As a non-limiting example, it includes, but is not limited to, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm or any of the foregoing ranges and values ​​within that range.

[0109] In some embodiments, the semi-bright nickel layer and the fully bright nickel layer are sequentially disposed on the surface of the metal substrate. To better understand the stacking of the semi-bright nickel layer and the fully bright nickel layer, specifically: the semi-bright nickel layer is disposed near the metal substrate, and the fully bright nickel layer is disposed near the gold plating layer. This application utilizes the potential difference created by the semi-bright nickel layer and the fully bright nickel layer to form a micro-cell effect. When the corrosive medium penetrates the bright nickel layer and reaches the interface, the bright nickel with the more negative potential acts as the anode and corrodes preferentially, while the semi-bright nickel with the more positive potential acts as the cathode and is protected, thereby delaying the corrosion of the base metal. This application further delays the corrosion of the base metal by sequentially disposing the semi-bright nickel layer and the fully bright nickel layer on the surface of the metal substrate, thereby utilizing the micro-cell effect formed by the two nickel layers.

[0110] In some embodiments, a semi-bright nickel layer and a fully bright nickel layer are sequentially disposed on the surface of the metal substrate in the composite structure.

[0111] In some embodiments, the composite structure further includes a passivation layer disposed between the gold plating layer and the sealant layer, which can further improve the corrosion resistance of the composite structure. As a non-limiting example, the passivation layer includes a potassium dichromate passivation layer and / or a chromic anhydride passivation layer.

[0112] In some embodiments, the thickness of the passivation layer is 200nm-500nm. As a non-limiting example, it includes, but is not limited to, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, or any combination thereof and values ​​within that range.

[0113] The composite structure provided in this application has excellent corrosion resistance and can exhibit the luster of gold, thus possessing excellent protective and decorative properties.

[0114] Fourthly, this application also provides a method for preparing a composite structure, comprising the following steps:

[0115] S20. Prepare the metal substrate.

[0116] S21. The metal substrate is placed in a nickel plating solution for treatment, and a nickel plating layer is formed on the surface of the metal substrate to prepare the first structure.

[0117] S22. The first structure is placed in a gold plating solution for treatment to form a gold plating layer on the surface of the first structure, thereby preparing the second structure.

[0118] S23. The second structure is placed in an electrodeposition sealing agent solution for treatment, and then photocured to form a sealing agent layer on the surface of the second structure, thereby preparing the composite structure provided in the third aspect.

[0119] In some embodiments, step S21 includes: treating a metal substrate in a semi-bright nickel plating solution and then treating it in a fully bright nickel plating solution, thereby sequentially forming a semi-bright nickel plating layer and a fully bright nickel plating layer on the surface of the metal substrate to prepare a first structure.

[0120] In some embodiments, step S21, where the metal substrate is placed in a nickel plating solution for treatment, includes electroplating.

[0121] In some embodiments, the electroplating process parameters in step S21 are: current density 2A / dm². 2 -5A / dm 2 Temperature 50℃-60℃, pH 3.8-4, and time 10min-40min.

[0122] In some embodiments, in step S21, the nickel plating solution comprises nickel sulfate, nickel chloride, and boric acid. Further, the nickel plating solution comprises 260 g / L-280 g / L nickel sulfate, 40 g / L-50 g / L nickel chloride, and 40 g / L-45 g / L boric acid.

[0123] In some embodiments, in step S21, the nickel plating solution further includes additives, which include one or more of 1,4-butynediol, sodium dodecyl sulfate, and saccharin. In some embodiments, in step S21, the nickel plating solution includes additives at a concentration of 0.01 g / L to 1.8 g / L. Optionally, the concentration of 1,4-butynediol in the nickel plating solution is 0.1 g / L to 0.5 g / L. Optionally, the concentration of sodium dodecyl sulfate in the nickel plating solution is 0.01 g / L to 0.1 g / L. Optionally, the concentration of saccharin in the nickel plating solution is 0.5 g / L to 1.2 g / L.

[0124] In some embodiments, in step S21, the first structure includes a semi-bright nickel plating layer and a fully bright nickel plating layer formed sequentially on the surface of a metal substrate.

[0125] In some embodiments, in step S21, the metal substrate is treated in a semi-bright nickel plating solution to form a semi-bright nickel plating layer on the surface of the metal substrate, and then the structure is treated in a fully bright nickel plating solution to prepare the first structure.

[0126] In some embodiments, the semi-bright nickel plating bath comprises nickel sulfate, nickel chloride, boric acid, 1,4-butynediol, and sodium dodecyl sulfate. Further, the semi-bright nickel plating bath comprises 260 g / L-280 g / L nickel sulfate, 40 g / L-50 g / L nickel chloride, 40 g / L-45 g / L boric acid, 0.1 g / L-0.5 g / L 1,4-butynediol, and 0.01 g / L-0.1 g / L sodium dodecyl sulfate.

[0127] In some embodiments, the electroplating process parameters of the semi-bright nickel plating solution are: current density 2A / dm³. 2 -5A / dm 2 Temperature 50℃-60℃, pH 3.8-4, and time 10min-20min.

[0128] In some embodiments, the composition of the full-brightness nickel plating bath includes nickel sulfate, nickel chloride, boric acid, 1,4-butynediol, sodium dodecyl sulfate, and saccharin. Further, the composition of the semi-brightness nickel plating bath includes 260 g / L-280 g / L nickel sulfate, 40 g / L-50 g / L nickel chloride, 40 g / L-45 g / L boric acid, 0.1 g / L-0.5 g / L 1,4-butynediol, 0.01 g / L-0.1 g / L sodium dodecyl sulfate, and 0.5 g / L-1.2 g / L saccharin.

[0129] In some embodiments, the electroplating process parameters of the all-bright nickel plating solution are: current density 2A / dm³. 2 -5A / dm 2 Temperature 50℃-60℃, pH 3.8-4, and time 30min-40min.

[0130] In some embodiments, step S22, treating the first structure in a gold plating solution, includes electroplating.

[0131] In some embodiments, in step S22, the gold plating solution comprises potassium gold cyanide. Further, the concentration of potassium gold cyanide added to the gold plating solution is 1 g / L-10 g / L.

[0132] In some embodiments, in step S22, the gold plating solution further comprises additives. Optionally, the additives include ammonium citrate. Further, the gold plating solution comprises additives at a concentration of 20 g / L to 60 g / L.

[0133] In some embodiments, in step S22, the electroplating process parameters are: current density 0.1 A / dm³. 2 -1A / dm 2Temperature 75℃-85℃, pH 5.5-5.8, and time 1 min-10 min.

[0134] In some embodiments, before the second structure is treated with an electrodeposition sealing agent, the second structure in step S22 is placed in a passivation solution to form a passivation layer on the surface of the second structure.

[0135] In some embodiments, the passivation solution comprises potassium dichromate and phosphoric acid. Further, the passivation solution comprises 25 g / L-35 g / L potassium dichromate and 8 mL / L-12 mL / L phosphoric acid.

[0136] In some embodiments, the process parameters for treating the second structure in a passivation solution include: a temperature of 20°C-30°C and a time of 25°C-35°C.

[0137] In some embodiments, in step S23, the treatment of the second structure in a sealing agent includes an electroplating process.

[0138] In some embodiments, step S23 includes: placing the second structure in an electrodeposition sealing agent for 2-5 minutes, then removing the second structure for cleaning, and then performing photocuring to form a sealing agent layer on the surface of the second structure.

[0139] In some embodiments, step S23 uses ultraviolet light for photocuring.

[0140] In some embodiments, the wavelength of the ultraviolet light is 200nm-400nm. As a non-limiting example, it includes, but is not limited to, 200nm, 275nm, 300nm, 325nm, 365nm, 400nm, or any combination thereof and values ​​within that range.

[0141] In some embodiments, the intensity of the ultraviolet light is 1500 mW / cm². 2 -3000 mW / cm 2 As a non-limiting example, including but not limited to 1500 mW / cm² 2 1800 mW / cm 2 2000 mW / cm 2 2200 mW / cm 2 2500 mW / cm 2 2800 mW / cm 2 3000 mW / cm 2 Or the range formed by either of the above and the values ​​within that range.

[0142] In some embodiments, the photocuring is performed by irradiation with a high-pressure mercury lamp.

[0143] In some embodiments, the photocuring time is 30s-120s. As a non-limiting example, it includes, but is not limited to, 30s, 45s, 60s, 80s, 100s, 120s, or any of the foregoing ranges and values ​​within those ranges.

[0144] In some embodiments, the electrodeposition sealing agent solution in step S23 is an aqueous solution of the electrodeposition sealing agent provided in the first aspect diluted with pure water to a concentration of 1%-5%.

[0145] In some embodiments, the processing temperature of step S23 is 40°C-45°C. As a non-limiting example, it includes, but is not limited to, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, or any range formed by both of the foregoing and values ​​within that range.

[0146] Furthermore, the cleaning temperature for the second structure is 45°C-50°C. As a non-limiting example, it includes, but is not limited to, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, or any combination thereof and values ​​within that range.

[0147] Furthermore, the solvent used to clean the second structure is pure water.

[0148] Furthermore, the cleaning time for the second structure is 0.5 min to 3 min. As a non-limiting example, it includes, but is not limited to, 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, or any combination thereof and values ​​within that range.

[0149] Furthermore, the drying temperature is 80°C-90°C. As a non-limiting example, it includes, but is not limited to, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, or any range formed by both of the foregoing and values ​​within that range.

[0150] Furthermore, the drying time is 40 min to 60 min. As a non-limiting example, it includes, but is not limited to, 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min, 60 min or any of the foregoing ranges and values ​​within those ranges.

[0151] The method for preparing the composite structure provided in this application is simple and can achieve a tight bond between the layers, thereby improving the corrosion resistance and protective effect of the composite structure.

[0152] Fifthly, this application also provides a metal fitting, which includes the composite structure provided in the third aspect, or the composite structure prepared by the method for preparing the composite structure provided in the fourth aspect.

[0153] Sixthly, this application also provides an article of manufacture comprising the metal fittings provided in the fifth aspect.

[0154] In some embodiments, the article includes kitchen and bathroom products.

[0155] It should be noted that experimental methods in the following embodiments of this application, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the embodiments are commercially available products, or can be prepared by those skilled in the art using known methods.

[0156] The types and sources of some of the raw materials and reagents involved in the specific embodiments of this application are as follows:

[0157] The low molecular weight bisphenol A type epoxy resin E-51 (618) was purchased from Jiangsu Congzhong Chemical Co., Ltd.

[0158] The low molecular weight bisphenol A type epoxy resin E-44 (6101) was purchased from Jiangsu Congzhong Chemical Co., Ltd.

[0159] The bisphenol F type epoxy resin was purchased from Jiangsu Congzhong Chemical Co., Ltd., model number EP06331-312.

[0160] Nano silica (10 nm particle size, model SS-S10, purchased from Hangzhou Jikang New Materials Co., Ltd.), nano silica (30 nm particle size, model SS-S50, purchased from Hangzhou Jikang New Materials Co., Ltd.), nano aluminum oxide (15 nm particle size, model JR14W, purchased from Xuancheng Jingrui Nanotechnology Co., Ltd.), and nano titanium dioxide (20 nm particle size, model VK-TA18H, purchased from Xuancheng Jingrui Nanotechnology Co., Ltd.)

[0161] Triphenylthionium hexafluoroantimonate (CAS No.: 57840-38-7), Triphenylthionium hexafluorophosphate (CAS No.: 57835-99-1), Diphenyliodonium hexafluorophosphate (CAS No.: 58109-40-3).

[0162] Example 1

[0163] This embodiment provides an electrodeposition sealing agent and its preparation method, as detailed below:

[0164] Materials used to prepare electrodeposition sealing agents, by mass percentage, include:

[0165] Low molecular weight bisphenol A type epoxy resin E-51 (618) 200 g

[0166] Butyl glycidyl ether 85 g

[0167] Nano aluminum oxide 25 g

[0168] Diphenyliodonium hexafluorophosphate 15 g

[0169] 15 g of dimethylsiloxane, and

[0170] 160 g of acetone.

[0171] The preparation method of the electrodeposition sealing agent includes:

[0172] First, low molecular weight bisphenol A epoxy resin (E-51 (618)) was poured into a container and then placed in a magnetic stirrer and stirred at 200 rpm. Then, butyl glycidyl ether, diphenyliodonium hexafluorophosphate, and acetone were added and stirred for 10 min. Dimethylsiloxane was added dropwise to the above solution, and after sealing, the mixture was stirred at the same speed for 25 min. Finally, nano-alumina was slowly added and stirred at the same speed for 60 min to ensure that the nano-alumina was evenly dispersed in the sealing agent, thus preparing the electrodeposition sealing agent.

[0173] Example 2

[0174] This embodiment provides an electrodeposition sealing agent and its preparation method, as detailed below:

[0175] The materials used to prepare the electrodeposition sealing agent, by weight percentage, include:

[0176] Low molecular weight bisphenol A type epoxy resin E-44 (6101) 150g

[0177] 100g of phenyl glycidyl ether

[0178] 10 g of nano-silica

[0179] 25 g of triphenylthionium hexafluoride phosphate

[0180] 15 g of dimethylsiloxane, and

[0181] 200 g of N,N-dimethylformamide.

[0182] The preparation method of the electrodeposition sealing agent is basically the same as that in Example 1.

[0183] Example 3

[0184] This embodiment provides an electrodeposition sealing agent and its preparation method, as detailed below:

[0185] The materials used to prepare the electrodeposition sealing agent, by weight percentage, include:

[0186] Bisphenol F type epoxy resin EP06331-312 175 g

[0187] 100 g of benzyl glycidyl ether

[0188] 15 g of nano titanium dioxide

[0189] Triphenylthionium hexafluoroantimonate 15g

[0190] 10g of dimethylsiloxane, and

[0191] 185g of ethanol.

[0192] The preparation method of the electrodeposition sealing agent is basically the same as that in Example 1.

[0193] Example 4

[0194] This embodiment provides an electrodeposition sealing agent and its preparation method, as detailed below:

[0195] The materials used to prepare the electrodeposition sealing agent, by weight percentage, include:

[0196] Low molecular weight bisphenol A type epoxy resin E-51 (618) 175 g

[0197] 50g of butyl glycidyl ether

[0198] 10 g of nano-alumina

[0199] Diphenyliodonium hexafluorophosphate 15 g

[0200] 50 g of dimethylsiloxane, and

[0201] 200 g of acetone.

[0202] The preparation method of the electrodeposition sealing agent is basically the same as that in Example 1.

[0203] Example 5

[0204] This embodiment provides a composite structure and its preparation method, as detailed below:

[0205] The copper alloy substrate undergoes a pre-plating treatment process, namely electroplating cleaning, which aims to remove impurities such as grease and dirt from the surface of the copper alloy substrate.

[0206] The cleaned copper alloy substrate was placed in a semi-bright nickel plating bath for anti-corrosion layer deposition. The main components of the semi-bright nickel plating bath were: nickel sulfate 260 g / L, nickel chloride 50 g / L, boric acid 40 g / L, 1,4-butynediol 0.3 g / L, and sodium dodecyl sulfate 0.01 g / L. The deposition process parameters were: current density 3 A / dm³. 2 A semi-bright nickel plating layer with a thickness of 6 μm ± 0.5 μm was formed on the surface of a copper alloy substrate at a temperature of 53℃, pH of 4, and a time of 12 min. The aforementioned structure was then placed in a fully bright nickel plating bath for anti-corrosion layer deposition. The main components of the fully bright nickel plating bath were: nickel sulfate 260 g / L, nickel chloride 50 g / L, boric acid 40 g / L, saccharin 0.8 g / L, 1,4-butynediol 0.4 g / L, and sodium dodecyl sulfate 0.06 g / L. The process parameters were: current density 3 A / dm³. 2 A fully bright nickel coating with a thickness of 12μm±0.5μm was formed on the surface of the semi-bright nickel coating by using a temperature of 53℃, pH 3.8 and a time of 25 min.

[0207] The copper alloy substrate containing the nickel plating layer was placed in a gold plating bath for gold deposition. The main components of the plating bath were potassium gold cyanide (6 g / L) and ammonium citrate (50 g / L). The process parameters were: current density 0.5 A / dm³. 2 A gold plating layer with a thickness of 0.35μm±0.2μm was formed on the surface of the fully bright nickel plating by setting the temperature to 80℃, pH to 5.6, and time to 5 min.

[0208] The copper alloy substrate containing nickel and gold plating was placed in a passivation solution. The passivation solution consisted of 30 g / L potassium dichromate and 10 mL / L phosphoric acid. The process parameters were 25°C and 30 s, forming a passivation layer with a thickness of 300 nm ± 50 nm on the surface of the gold plating.

[0209] The copper alloy substrate containing the nickel plating, gold plating, and passivation layer was completely immersed in an electrodeposition sealing agent solution (prepared by mixing the electrodeposition sealing agent prepared in Example 1 with pure water at 45°C in a ratio of 30 mL: 970 mL) for 3 minutes. Then, the copper alloy substrate was removed and immersed in pure water at 45°C for 0.5 minutes, followed by rinsing in pure water at room temperature for 1.5 minutes. The cleaned copper alloy substrate was then irradiated under a high-pressure mercury lamp (main wavelength 365 nm) with a light intensity of 2000 mW / cm². 2 Photocuring was performed for 60 seconds to form a sealing agent layer on the surface of the passivation layer, thus obtaining a composite structure.

[0210] Example 6

[0211] This embodiment provides a composite structure and its preparation method. The difference from Example 5 is that the copper alloy substrate containing nickel plating, gold plating and passivation layer is placed in different electrodeposition sealing agent solutions. The electrodeposition sealing agent solution in this embodiment is prepared by mixing the electrodeposition sealing agent prepared in Example 1 with pure water at 45°C in a ratio of 50mL:950mL. The rest of the preparation method is basically the same as that in Example 5.

[0212] Example 7

[0213] This embodiment provides a composite structure and its preparation method. The difference from Example 5 is that the copper alloy substrate containing nickel plating, gold plating and passivation layer is placed in different electrodeposition sealing agent solutions. The electrodeposition sealing agent solution in this embodiment is prepared by mixing the electrodeposition sealing agent prepared in Example 1 with pure water at 45°C in a ratio of 10mL:990mL. The rest of the preparation method is basically the same as that in Example 5.

[0214] Example 8

[0215] This embodiment provides a composite structure and its preparation method. The difference from Example 5 is that the electrodeposition sealing agent is the electrodeposition sealing agent prepared in Example 2, while the rest of the preparation method is basically the same as that in Example 5.

[0216] Example 9

[0217] This embodiment provides a composite structure and its preparation method. The difference from Example 5 is that the electrodeposition sealing agent is the electrodeposition sealing agent prepared in Example 3, while the rest of the preparation method is basically the same as that in Example 5.

[0218] Example 10

[0219] This embodiment provides a composite structure and its preparation method. The difference between this embodiment and Example 5 is that the electrodeposition sealing agent is the electrodeposition sealing agent prepared in Example 4, while the rest of the preparation method is basically the same as in Example 5.

[0220] Example 11

[0221] This embodiment provides a composite structure and its preparation method. The difference between this embodiment and Example 5 lies in the materials used to prepare the electrodeposition sealing agent. By mass percentage, the materials used to prepare the electrodeposition sealing agent in this embodiment include:

[0222] Low molecular weight bisphenol A type epoxy resin E-44 (6101) 130 g

[0223] 90 g of phenyl glycidyl ether

[0224] 50 g of nano-silica

[0225] 15 g of triphenylthionium hexafluoride phosphate

[0226] 15 g of dimethylsiloxane, and

[0227] 200 g of N,N-dimethylformamide.

[0228] The preparation method of the electrodeposition sealing agent is basically the same as that in Example 1, and the preparation method of the composite structure is basically the same as that in Example 5.

[0229] Example 12

[0230] This embodiment provides a composite structure and its preparation method. The difference between this embodiment and Example 5 lies in the particle size of the sealing agent in the electrodeposition sealing agent. In this embodiment, the particle size of the nano-alumina is 2 nm. The preparation method of the electrodeposition sealing agent is basically the same as that of Example 1, and the preparation method of the composite structure is basically the same as that of Example 5.

[0231] Example 13

[0232] This embodiment provides a composite structure and its preparation method. The difference between this embodiment and Embodiment 5 lies in the electrodeposition sealing agent treatment process. The electrodeposition sealing agent treatment process in this embodiment is as follows:

[0233] The copper alloy substrate containing nickel plating, gold plating, and passivation layer prepared in Example 5 was completely immersed in an electrodeposition sealing agent solution (prepared by mixing the electrodeposition sealing agent prepared in Example 1 with pure water at 45°C in a ratio of 30 mL: 970 mL) for 1 min. The copper alloy substrate was then removed, rinsed in pure water at 45°C for 0.5 min, and then rinsed in pure water at room temperature for 1.5 min. The cleaned copper alloy substrate was then irradiated under a high-pressure mercury lamp (main wavelength 365 nm) with a light intensity of 1500 mW / cm². 2 Photocuring was performed for 30 seconds to form a sealing agent layer on the surface of the passivation layer, thus obtaining a composite structure.

[0234] The remaining steps are basically the same as in Example 5.

[0235] Comparative Example 1

[0236] This comparative example provides a composite structure and preparation method. The composite structure in this comparative example is prepared without any electrodeposition sealing agent treatment. The remaining steps are the same as in Example 5. The composite structure prepared in this comparative example is a copper alloy substrate and a semi-bright nickel plating layer, a fully bright nickel plating layer, a gold plating layer and a passivation layer formed sequentially on the surface of the copper alloy substrate.

[0237] Comparative Example 2

[0238] This comparative example provides a composite structure and its preparation method. The electrodeposition sealing agent used in the preparation process of the composite structure in this comparative example is different.

[0239] The difference between the electrodeposition sealing agent used in this comparative example and that in Example 1 is that the photoinitiator is replaced with an equal amount of free radical photoinitiator (ethyl benzoylformate) instead of diphenyliodonium hexafluorophosphate, while the other materials and contents used to prepare the electrodeposition sealing agent are the same as in Example 1.

[0240] The remaining preparation steps of the composite structure in this comparative example are the same as those in Example 5. The composite structure prepared in this comparative example is a copper alloy substrate, and a semi-bright nickel plating layer, a fully bright nickel plating layer, a gold plating layer, a passivation layer and a sealing agent layer formed sequentially on the surface of the copper alloy substrate.

[0241] Comparative Example 3

[0242] This comparative example provides a composite structure and its preparation method. The electrodeposition sealing agent used in the preparation process of the composite structure in this comparative example is different.

[0243] The difference between the electrodeposition sealant used in this comparative example and that in Example 1 is that the particle size of the nano-alumina is 30 nm, while the composition and content of the other electrodeposition sealant are the same as in Example 1.

[0244] The remaining preparation steps of the composite structure in this comparative example are the same as those in Example 5. The composite structure prepared in this comparative example is a copper alloy substrate, and a semi-bright nickel plating layer, a fully bright nickel plating layer, a gold plating layer, a passivation layer and a sealing agent layer formed sequentially on the surface of the copper alloy substrate.

[0245] Experimental Example 1

[0246] The composite structures prepared in Examples 5-13 and Comparative Examples 1-3 were subjected to performance tests. The test indicators included porosity, corrosion resistance, salt spray resistance, water contact angle, and appearance. The specific test methods are as follows:

[0247] (1) Porosity: Based on the principle of chemical reaction between potassium ferrocyanide and the base metal under the gold plating, if there are pores in the gold plating, the potassium ferrocyanide solution will react with the base metal through the pores to generate a blue copper ferrocyanide precipitate. The porosity is assessed by observing the number and size of the blue spots on the filter paper. After thoroughly wetting the filter paper with tweezers in the potassium ferrocyanide solution, remove it and attach it to the gold plating surface of the composite structure sample, ensuring that the filter paper adheres tightly to the gold plating surface and avoiding the formation of bubbles and wrinkles. Keep the filter paper on the sample surface for a period of time (generally 15-30 minutes) to allow the potassium ferrocyanide to react fully with the base metal. After the reaction is complete, remove the filter paper and let it dry. Observe the blue spots on the filter paper against a white background.

[0248] (2) Corrosion performance: Electrochemical tests were conducted on the composite structure samples using an RST5200 electrochemical workstation. A three-electrode testing system was used, with the working electrode being a nickel electrode (1cm). 2 The counter electrode was a platinum electrode, and the reference electrode was a saturated calomel electrode. The test solution was a 0.5M H₂SO₄ solution at room temperature. The potential-time curve test duration was 3400 s; the polarization curve test scan rate was 2 mV / s; the electrochemical impedance spectroscopy amplitude was 7 mV / s, and the frequency was 0.01 Hz-10 Hz.

[0249] (3) Salt spray resistance: In the AASS salt spray test, a certain amount of glacial acetic acid needs to be added to the 3.5% sodium chloride solution to make the pH value of the solution reach 3.1-3.3. Fix the composite structure sample on the sample rack in the test chamber and ensure that the sample placement angle meets the standard requirements. Generally, the flat sample should be at an angle of 15°-30° to the vertical direction, and the test surface should be exposed to the salt spray as much as possible. Pour the prepared salt solution into the solution tank of the salt spray test chamber, start the test chamber, and start the salt spray generator. At the same time, set the temperature of the test chamber to 35℃±2℃. Test time setting: Determine the appropriate test time according to the sample's usage environment and requirements. After the test, take out the sample, rinse it with clean water, and then let it air dry at room temperature or dry it with a hair dryer or other equipment. Evaluation methods include visual inspection, corrosion rating, measurement of the quality or thickness of corrosion products, etc. For example, the degree of corrosion is divided into different levels according to the percentage of the corrosion area to the total area, from level 10 (no corrosion) to level 0 (severe corrosion). For example, a grade of 10 indicates that there is no corrosion at all and the surface condition is the same as before the test; while a grade of 0 indicates that the corrosion area exceeds 95% and the sample has been severely damaged.

[0250] (4) Water contact angle: The water contact angle of the sample surface was measured using a contact angle meter (OCA20, Germany). The test method was the pendant drop method, which involves placing a water droplet on the sample surface and taking an image of the sample surface using a microscope to study the hydrophilicity and hydrophobicity of the obtained sample. The amount of each water droplet was 5 μL. Three parallel samples were selected for each type of sample for measurement.

[0251] (5) Appearance: When observed with the naked eye, the surface should be free of pits, bubbles, wrinkles, cracks, peeling or corrosion, and slight color changes and loss of gloss are not allowed.

[0252] The results obtained using the above-described testing method are shown in Table 1 and Appendix. Figure 1 Appendix Figure 2 As shown.

[0253] Table 1: Performance test results of the composite structure

[0254]

[0255] See appendix Figure 1 and attached Figure 2 SEM characterization results show that the electrodeposition sealant provided in this application can fill the pores of the gold plating layer, improving its density. Simultaneously, the use of inorganic nanomaterials with a particle size of 5nm-20nm gives the gold plating layer a large water contact angle and good hydrophobicity, significantly reducing the adhesion and penetration of corrosive media on the gold plating layer surface, thus improving its protective capability and service life. Furthermore, the gloss of the gold plating layer surface is not significantly affected. In contrast, gold plating layers not treated with the electrodeposition sealant of this application have high porosity and small contact angles. Moreover, the sealant system of this application requires the use of a specific type of photoinitiator to achieve the technical effects described herein. The particle size of the inorganic nanomaterials in the sealant system exceeding 20nm can, to some extent, reduce the effectiveness of the electrodeposition sealant. Therefore, the electrodeposition sealant of this application can significantly improve the corrosion resistance of the gold plating layer.

[0256] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0257] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An electrodeposition sealing agent, characterized in that, Materials used to prepare electrodeposition sealing agents include epoxy resin, reactive diluent, sealing agent, photoinitiator, additives, and solvent; The photoinitiator includes a cationic photoinitiator; The sealing agent comprises inorganic nanomaterials with a particle size of 5nm-20nm.

2. The electrodeposition sealing agent according to claim 1, characterized in that, Materials used to prepare electrodeposition sealing agents, by mass percentage, include: Epoxy resin 30%-40%, 10%-20% reactive diluent Sealing agent 2%-5%, Photoinitiator 3%-5%, Additives 2%-10%, and Solvent 30%-45%.

3. The electrodeposition sealing agent according to claim 1, characterized in that, The materials used to prepare the electrodeposition sealing agent also satisfy at least one of the following characteristics (1) to (8): (1) The epoxy equivalent of the epoxy resin is 160 g / eq-230 g / eq; (2) The solid content of the epoxy resin is 95%-100% by mass; (3) The average molecular weight of the epoxy resin is 360 g / mol-488 g / mol; (4) The active diluent includes one or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, propenyl glycidyl ether, p-cresol glycidyl ether, glycidyl methacrylate, diglycidyl ether, ethylene glycol diglycidyl ether and resorcinol diglycidyl ether; (5) The inorganic nanomaterials include one or more of nano-silicon-based oxides, nano-aluminum-based oxides, and nano-titanium-based oxides; Optionally, the nano-silicon-based oxide includes nano-silicon dioxide; Optionally, the nano-aluminum-based oxide includes nano-aluminum oxide; Optionally, the nano-titanium-based oxide includes nano-titanium dioxide; (6) The cationic photoinitiator includes one or more of iodonium salt photoinitiators and thionium salt photoinitiators; Optionally, the iodonium salt photoinitiator includes diphenyliodonium hexafluorophosphate; Optionally, the thionium salt photoinitiator includes one or more of triphenylthionium hexafluoroantimonate, triphenylthionium hexafluorophosphate, and others. (7) The additives include one or more of leveling agents and antioxidants; Optionally, the leveling agent includes a silicone leveling agent; Further optionally, the silicone leveling agent includes one or more of dimethylsiloxane, polyether-modified silicone, and polyester-modified silicone; Optionally, the antioxidant includes hindered phenolic antioxidants; (8) The solvent includes organic solvents; Optionally, the organic solvent includes one or more of ethanol, acetone, N,N-dimethylformamide and N,N-dimethylacetamide.

4. The method for preparing the electrodeposition sealing agent according to any one of claims 1 to 3, characterized in that, Includes the following steps: While the epoxy resin is being stirred, a photoinitiator, an active diluent, and a solvent are added and mixed to form a first dispersion. Add an auxiliary agent to the first dispersion and mix to form a second dispersion; Add a sealing agent to the second dispersion and mix to form an electrodeposition sealing agent.

5. A composite structure, characterized in that, It includes a metal substrate and a nickel plating layer, a gold plating layer, and a sealant layer sequentially stacked on the surface of the metal substrate; the sealant layer is formed by electrodeposition of the sealant as described in any one of claims 1 to 3.

6. The composite structure according to claim 5, characterized in that, The composite structure also satisfies at least one of the following features (1) to (4): (1) The metal substrate includes one or more of copper alloy, zinc alloy and stainless steel; (2) The thickness of the nickel plating is 15μm-20μm; (3) The nickel plating layer includes a semi-bright nickel layer and / or a fully bright nickel layer; Optionally, the thickness of the semi-bright nickel layer is 5μm-7μm; Optionally, the thickness of the all-bright nickel layer is 10μm-13μm; Optionally, in the composite structure, the semi-bright nickel layer and the fully bright nickel layer are sequentially stacked on the surface of the metal substrate; (4) The thickness of the gold plating layer is 0.3μm-0.4μm.

7. The composite structure according to claim 5, characterized in that, The composite structure also includes a passivation layer, which is stacked between the gold plating layer and the sealant layer; Optionally, the passivation layer includes a potassium dichromate passivation layer and / or a chromic anhydride passivation layer; Optionally, the thickness of the passivation layer is 200nm-500nm.

8. The method for preparing the composite structure according to any one of claims 5 to 7, characterized in that, Includes the following steps: Prepare the metal substrate; A first structure is prepared by placing a metal substrate in a nickel plating solution and forming a nickel plating layer on the surface of the metal substrate. The first structure is placed in a gold plating solution for treatment, and a gold plating layer is formed on the surface of the first structure to prepare the second structure; The second structure is placed in an electrodeposition sealing agent solution for treatment, and then photocured to form a sealing agent layer on the surface of the second structure, thus preparing a composite structure. Optionally, before the second structure is treated with an electrodeposition sealing agent, the second structure is placed in a passivation solution to form a passivation layer on the surface of the second structure.

9. The method for preparing the composite structure according to claim 8, characterized in that, The preparation method also satisfies at least one of the following (1) to (4): (1) The process of treating the second structure in the electrodeposition sealing agent includes: treating the second structure in the electrodeposition sealing agent for 2 min-5 min, and then taking out the second structure for cleaning; (2) The electrodeposition sealing agent solution is an electrodeposition sealing agent solution diluted with water to a concentration of 1%-5%; (3) Ultraviolet light is used for photocuring; Optionally, the wavelength of the ultraviolet light is 200nm-400nm; Optionally, the intensity of the ultraviolet light is 1500 mW / cm². 2 -3000 mW / cm 2 ; (4) The curing time is 30s-120s.

10. A metal fitting, characterized in that, The metal fittings include the composite structure described in any one of claims 5 to 7.

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