High-temperature-resistant anti-discoloration water-based copper protective agent, using method and copper workpiece

Abstract

The invention relates to a high-temperature-resistant anti-discoloration water-based copper protective agent, a using method and a copper workpiece, the copper protective agent is composed of 30%-65.5% of film forming matter, 0.1%-3% of solution stabilizer, 0.1%-1% of thickening agent, 0.1%-1% of flatting agent, 0.1%-1% of wetting agent and 30%-69% of deionized water, the film forming matter comprises lithium silicate aqueous solution, sodium silicate and sodium phosphate, and the solution stabilizer comprises sodium silicate and sodium phosphate. The stabilizer comprises a phosphoric acid aqueous solution and a boric acid aqueous solution, the thickening agent comprises sodium polyacrylate, the flatting agent is a polyether modified polysiloxane flatting agent, the wetting agent is a modified organic silicon wetting agent, and the corrosion inhibitor comprises sodium molybdate. When in use, a compact transparent protective layer is formed on the copper surface through the processes of copper piece pretreatment (sulfuric acid-hydrochloric acid-nitric acid polishing solution polishing treatment), protective agent dipping, centrifugal spin-drying and drying. Compared with the prior art, the protective layer enables the copper workpiece to be colorless and transparent after being treated at 250 DEG C for 6 hours, has no obvious color change, has excellent high-temperature-resistant and anti-discoloration performance, and is high in solid content and low in transportation cost.

Description

Technical Field

[0001] This invention relates to the field of corrosion protection and anti-discoloration treatment of non-ferrous metal copper surfaces, and in particular to a high-temperature resistant, anti-discoloration water-based copper protective agent, its application method, and copper workpieces. Background Technology

[0002] Metallic materials are widely used in daily life and engineering. Most metals are highly susceptible to corrosion by water vapor and corrosive media in the air. Statistics show that 20% to 40% of metal production is scrapped annually due to corrosion. Copper, due to its good thermal conductivity and excellent machinability, is widely used in wires, heat exchangers, and heat conductors. However, copper is easily corroded and discolored, especially at high temperatures, which greatly limits its service life and application range. Therefore, inhibiting copper discoloration has become an important research direction. Existing copper protection methods are divided into five main categories: organic coatings, inorganic plating, corrosion inhibitors, electrochemical protection, and alloying. Among these, copper-based corrosion inhibitors, with organic compounds as the main coating component, are difficult to withstand temperatures above 200°C and lack high-temperature stability. For example, patents CN111434801A and CN113106460A, while exhibiting high-temperature resistance up to 200°C, only maintain their non-discoloration time within 3-30 minutes, indicating that their high-temperature resistance still needs improvement.

[0003] Silicates, as one of the most abundant inorganic salt resources in nature, possess advantages such as low cost, abundant production, and environmental friendliness. Among them, water-soluble lithium silicate and sodium silicate are two key functional components, exhibiting high-temperature stability in their crystalline state. A solution of these two compounds in a specific ratio, after drying, can form a three-dimensional -Si-O-Si-reticulated framework on a metal surface, forming a film-forming mechanism. This framework can effectively fill microcracks in the copper matrix, and the embedded insoluble basic phosphate particles generated by sodium phosphate in an alkaline environment can further enhance the structural density and achieve microstructure reinforcement.

[0004] Chinese patent CN117230501A discloses a method for preparing a high-temperature resistant alkaline zinc-nickel plating sealant. The steps are as follows: the film-forming substance (accounting for 5-30% of the total solution formulation) is mainly composed of lithium silicate and sodium silicate, with the addition of inorganic salts such as sodium aluminate, sodium tungstate, sodium zincate, and sodium stannate. After dissolving in deionized water, a wetting agent, solution stabilizer, and sealing layer stabilizer are added. After immersion and drying, an alkaline zinc-nickel plating workpiece can form a protective coating. Workpieces using this sealant can withstand a dehydrogenation temperature of 200-250℃. However, the sodium tungstate contained in this patent formulation affects the dispersibility of the protective agent, resulting in a low solid content of the sealant, which can only be used in undiluted form, leading to higher transportation costs in practical applications. In addition, the low solid content system results in a slow film deposition rate during workpiece immersion, requiring extended immersion time to ensure film thickness, thus reducing production efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant, anti-discoloration water-based copper protective agent, its application method, and copper workpieces. The copper protective agent can effectively improve the high-temperature resistance of copper workpieces, has a high solids content, low transportation costs, and a short protective layer deposition time during use, which helps to reduce costs and improve production efficiency.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One objective of this invention is to provide a high-temperature resistant, anti-discoloration water-based copper protective agent, which comprises the following components by weight percentage:

[0008]

[0009] Preferably, the film-forming substance includes an aqueous solution of lithium silicate, sodium silicate, and sodium phosphate.

[0010] Preferably, the mass ratio of the lithium silicate aqueous solution, sodium silicate, and sodium phosphate is 55-75:3-7:0.5-1.5.

[0011] More preferably, the mass ratio of the lithium silicate aqueous solution, sodium silicate, and sodium phosphate is 60:5:1.

[0012] Preferably, the solid content of the lithium silicate aqueous solution is 20-25% (by mass).

[0013] More preferably, the solid content of the lithium silicate aqueous solution is 23%.

[0014] In this invention, the film-forming material includes lithium silicate, sodium silicate, and sodium phosphate. The resulting film is transparent, uniform, and strong. The phosphate forms a basic phosphate in the film. This phosphate exists in the solution as small particles, which can effectively block the gaps on the surface of the copper part and also make the protective layer more stable. After being treated at 250°C for 6 hours, the film remains transparent, colorless, and does not peel off, and the surface of the copper workpiece remains intact and does not change color.

[0015] Preferably, the stabilizer includes an aqueous solution of phosphoric acid and an aqueous solution of boric acid.

[0016] Preferably, the volume ratio of the phosphoric acid aqueous solution to the boric acid aqueous solution is 1.5-2.5:0.5-1.5.

[0017] More preferably, the volume ratio of the phosphoric acid aqueous solution to the boric acid aqueous solution is 2:1.

[0018] Preferably, the mass fraction of the phosphoric acid aqueous solution is 38%-50%, and the concentration of the boric acid aqueous solution is 0.8-1.2 mol / L.

[0019] More preferably, the concentration of the boric acid aqueous solution is 1 mol / L.

[0020] In this invention, the stabilizers are phosphoric acid and boric acid, which act as stabilizers and pH adjusters to prevent precipitation in the solution due to excessive acidity or alkalinity. They also provide corrosion protection. The corrosion protection effect of phosphoric acid and boric acid is based on the core principle of "isolating the corrosive medium": phosphoric acid reacts with ions on the metal surface to form a dense phosphate passivation film; boric acid molecules can be adsorbed onto the metal surface to form an adsorption film. These two films together prevent the contact between the corrosive medium and the metal surface, thereby achieving the corrosion protection effect.

[0021] Preferably, the thickener comprises sodium polyacrylate.

[0022] In this invention, the thickener is sodium polyacrylate, which possesses highly efficient thickening properties and excellent suspension stability. On the one hand, it can effectively suspend the protective agent, preventing precipitation and clumping during storage, thereby extending the product's shelf life; on the other hand, while achieving a thickening effect, it can also significantly increase the amount of protective agent adhering during use, ensuring that the protective agent forms an effective film thickness after film formation.

[0023] Preferably, the leveling agent is a polyether-modified polysiloxane leveling agent.

[0024] More preferably, the polyether-modified polysiloxane leveling agent includes any one of a polydimethylsiloxane copolymer co-modified with long-chain alkyl groups and polyether or a polyether-modified polydimethylsiloxane.

[0025] In this invention, the leveling agent is a polyether-modified polysiloxane leveling agent. As an environmentally friendly leveling agent, it combines the excellent surface tension reduction ability of organosilicon with the good compatibility and foam stabilization and defoaming control capabilities of polyether segments, and exhibits excellent stability in alkaline environments. This leveling agent can effectively reduce the surface tension of the system, improve wettability, reduce the generation of surface defects such as pinholes and craters, and promote the uniform spreading of the protective agent on the copper surface, thereby achieving a smooth and even surface finish on the copper.

[0026] Preferably, the wetting agent is a modified organosilicon wetting agent.

[0027] More preferably, the modified organosilicon wetting agent includes 8241 wetting agent.

[0028] In this invention, the wetting agent reduces the surface tension of the liquid, helping the protective agent to better wet the substrate surface, and also promotes the protective agent to penetrate more fully into the coating cracks. Furthermore, it eliminates microbubbles and voids in the protective agent, resulting in a more uniform protective film formed after drying.

[0029] Preferably, the corrosion inhibitor comprises sodium molybdate.

[0030] In this invention, the corrosion inhibitor is sodium molybdate, which, as an environmentally friendly corrosion inhibitor, promotes the formation of a composite passivation film rich in molybdenum oxide / molybdate on the copper surface, significantly improving the corrosion resistance of copper.

[0031] The second objective of this invention is to provide a method for using the aforementioned high-temperature resistant, anti-discoloration water-based copper protective agent, comprising the following steps:

[0032] S1: Weigh the film-forming substance, stabilizer, thickener, leveling agent, wetting agent, and corrosion inhibitor according to the formula, and disperse them in deionized water to obtain a copper protectant;

[0033] S2: Immerse the copper workpiece in a copper protective agent at 5-40°C for 30-90 seconds, then remove the residual solution from the surface of the copper workpiece and dry it.

[0034] Preferably, step S1 involves weighing an aqueous solution of lithium silicate, sodium silicate, sodium phosphate, an aqueous solution of phosphoric acid, an aqueous solution of boric acid, sodium polyacrylate, a polyether-modified polysiloxane leveling agent, a modified organosilicon wetting agent, and sodium molybdate, and then dispersing them in deionized water to obtain a copper protectant.

[0035] More preferably, the solvent water content in the lithium silicate aqueous solution, phosphoric acid aqueous solution, and boric acid aqueous solution is not included in the deionized water content.

[0036] Preferably, in step S2, the immersion treatment time is 60 seconds.

[0037] Preferably, in step S2, residual solution on the surface of the copper workpiece is removed by dripping or centrifugation.

[0038] More preferably, in step S2, the centrifugation speed is 200-400 r / min.

[0039] More preferably, in step S2, the centrifugation includes rotating clockwise for 10s-30s and counterclockwise for 10s-30s at a centrifugation speed of 200-400r / min.

[0040] More preferably, the centrifugation time is adjusted according to the complexity of the parts.

[0041] More preferably, the centrifugation is carried out using a spin-drying centrifuge commonly used in the coatings industry.

[0042] More preferably, in step S2, the drying temperature is 90-120℃ and the drying time is 10-30 min.

[0043] In this invention, the drying temperature and the drying holding time are inversely proportional: a higher temperature can be used for a shorter time, and vice versa.

[0044] More preferably, in step S2, the drying temperature is 110°C and the drying time is 15 minutes.

[0045] Preferably, in step S2, before immersing the copper workpiece in the copper protectant, a pretreatment step is also included: treating the copper workpiece in a polishing solution, then rinsing it with deionized water and ultrasonicating it, and then drying it after ultrasonication.

[0046] More preferably, in step S2, the polishing solution is prepared by mixing any one of sulfuric acid, hydrochloric acid, OY-110 pickling brightener, clean water, and nitric acid or sodium nitrate solution in a volume ratio of 40:5:2:50-58:7 at a temperature of 5-40°C.

[0047] More preferably, the sulfuric acid is industrial grade sulfuric acid with a relative density d = 1.84.

[0048] More preferably, the hydrochloric acid is industrial grade hydrochloric acid with a relative density d = 1.18.

[0049] More preferably, the nitric acid is industrial grade nitric acid with a relative density d = 1.41.

[0050] More preferably, the concentration of the sodium nitrate solution is 65-75 g / L, and even more preferably 70 g / L.

[0051] More preferably, in step S2, the ultrasonic cleaning time is 30-120 seconds, and the ultrasonic power is 600W-1200W.

[0052] More preferably, if the surface of the copper workpiece already has no oxide or organic protective layer, it can be directly impregnated.

[0053] The third objective of this invention is to provide a copper workpiece containing a high-temperature resistant and anti-discoloration water-based copper protective layer, comprising a copper workpiece and a copper protective layer thereon. The copper protective layer is prepared on the copper workpiece using the high-temperature resistant and anti-discoloration water-based copper protective agent as described above. The copper protective layer has a -Si-O-Si- network structure and a thickness of 1-2 μm.

[0054] Preferably, the workpiece is made of copper or a copper-based alloy.

[0055] More preferably, the copper workpiece is a pure copper workpiece.

[0056] Preferably, the copper protective layer is colorless, transparent, uniform, and firmly bonded.

[0057] Preferably, the high-temperature resistant, anti-discoloration water-based copper protectant can form a network structure with -Si-O-Si- as the main component on the surface of the copper workpiece, which adheres to the surface of the workpiece and fully isolates the contact between gaseous and liquid substances and the surface layer of the workpiece, thereby achieving the effect of preventing copper discoloration.

[0058] Preferably, the copper protective layer remains transparent, colorless, and does not peel after being treated at 250°C for 6 hours, and the surface of the copper workpiece containing the copper protective layer remains intact and does not change color.

[0059] This invention provides a high-temperature resistant, anti-discoloration water-based copper protectant with inorganic lithium silicate / sodium silicate as the core component. It aims to replace existing models (mainly used for color protection of copper materials in atmospheric environments), overcome the technical bottleneck of insufficient temperature resistance of traditional organic anti-discoloration agents, and replace existing copper-based corrosion inhibitors containing organic matter that are not resistant to temperatures above 200°C.

[0060] This invention provides a high-temperature resistant, colorfast water-based copper protective agent. The agent comprises a film-forming substance (30%-65.5%), a solution stabilizer (0.1%-3%), a thickener (0.1%-1%), a leveling agent (0.1%-1%), a wetting agent (0.1%-1%), and deionized water (30%-69%). The film-forming substance is primarily lithium silicate, compounded with sodium silicate, sodium phosphate, etc., to form a -Si-O-Si- network structure film. Preparation involves copper pretreatment (polishing with sulfuric acid-hydrochloric acid-nitric acid polishing solution), impregnation with the protective agent, centrifugal drying, and drying at 110°C to form a dense, transparent protective layer on the copper surface. This protective agent is water-based and environmentally friendly, exhibiting significantly better temperature resistance than traditional organic coatings, and can withstand high temperatures of 200-300°C and 48 hours of salt spray testing without discoloration. Sodium molybdate, as an environmentally friendly corrosion inhibitor, promotes the formation of a composite passivation film rich in molybdenum oxide / molybdate on the copper surface, significantly improving the corrosion resistance of copper. Sodium phosphate forms basic phosphate particles that block plating gaps, and combined with a leveling agent, reduces surface tension, achieving uniform film formation. Examples show that the protective layer remains colorless and transparent after treatment at 250°C for 6 hours, exhibiting excellent tensile crack protection. It can be widely used for high-temperature environmental protection and decorative treatment of copper and alloy workpieces.

[0061] The existing technology (CN117230501A) produces a solution with a pH value between 11 and 12. However, when the pH is greater than 11, the solubility of sodium tungstate drops to below 30g Na2WO4 / 100g H2O. Simultaneously, under highly alkaline conditions, sodium tungstate readily forms stable polymeric tungstates (such as [WO4]2[W6O). 19 ] 4-This leads to a significant decrease in its solubility. This reduced solubility directly affects the dispersion performance of the protective agent, thus limiting the increase in the overall solid content of the system. Too low a solid content means a high proportion of solvent (such as water) and a low proportion of effective active ingredients, which not only increases transportation and storage costs but also weakens the performance and film-forming efficiency of the final film. This invention uses sodium molybdate as a corrosion inhibitor, which effectively increases the concentration of the protective agent, allowing the proportion of film-forming material to exceed 60%. This high-concentration protective agent can be diluted with water at a 1:1 ratio in practical applications, thereby significantly reducing transportation costs. Furthermore, the film formed by this invention has a fast deposition rate, requiring only 30-90 seconds of immersion treatment at 5-40°C, demonstrating excellent production efficiency.

[0062] Furthermore, this invention uses sodium polyacrylate as a thickener, which effectively increases the amount of protective agent remaining on the copper surface, thus thickening the protective layer. When used in conjunction with a chemical polishing pretreatment, this invention achieves even better protective effects.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] (1) The present invention uses lithium silicate, sodium silicate and sodium phosphate as film-forming substances, phosphoric acid and boric acid as stabilizers, sodium polyacrylate as thickener, sodium molybdate as corrosion inhibitor, and adds modified organosilicon wetting agent and polyether modified polysiloxane leveling agent, thereby providing a high temperature resistant and anti-discoloration water-based copper protective agent. This copper protective agent can effectively improve the high temperature resistance of copper workpieces, and has a high solid content. When used, the protective layer deposition time is short, which is conducive to reducing transportation costs and improving production efficiency.

[0065] (2) The present invention is an environmentally friendly water-based protective agent. The copper protective layer prepared on the surface of copper workpiece using this protective agent has excellent anti-rust and high temperature resistance properties. It can withstand high temperature of 200-300℃ for ten hours without discoloration of the copper.

[0066] (3) The surface of the copper workpiece treated with the protective agent of this invention exhibits excellent leveling properties, effectively avoiding defects such as orange peel and shrinkage cavities. The film thickness between 1 and 2 micrometers has little impact on the substrate size. The film surface displays a uniform color with no visual difference from the substrate, and the film thickness uniformity is good.

[0067] (4) The present invention uses sodium molybdate as a corrosion inhibitor, which can promote the formation of a composite passivation film rich in molybdenum oxide / molybdate on the copper surface, significantly improving the corrosion resistance of copper; on the other hand, sodium molybdate can effectively increase the concentration of the protective agent, increase the solid content of the protective agent, reduce transportation costs, and at the same time make the film deposition rate fast when using the protective agent to prepare a protective layer on the surface of copper workpieces, and the immersion treatment at 5-40℃ for 30-90s is sufficient, thereby effectively improving production efficiency.

[0068] (5) In this invention, lithium silicate is the main component, and sodium silicate, sodium phosphate and other components are compounded to form a -Si-O-Si- network structure film. The film is transparent, uniform and firm. Phosphate can effectively block the gaps in the coating. Phosphoric acid can react with ions on the metal surface to generate a dense phosphate passivation film. Boric acid molecules can be adsorbed on the metal surface to form an adsorption film. These two films together prevent the contact between the corrosive medium and the metal surface, thereby achieving the anti-corrosion effect.

[0069] (6) In this invention, sodium polyacrylate has efficient thickening properties and suspension stability, and can also increase the amount of protective agent adhering when used, ensuring that the protective agent forms an effective film thickness after film formation; polyether modified polysiloxane leveling agent and modified organosilicon wetting agent can both effectively reduce the surface tension of the system and improve wettability. At the same time, the former can reduce surface defects such as pinholes and pinholes, while the latter can promote the protective agent to penetrate into the coating cracks more fully, so that the protective film formed after the protective agent is dried is more uniform.

[0070] (7) Before immersing the copper workpiece in the copper protective agent, the present invention requires copper workpiece pretreatment and polishing treatment with sulfuric acid-hydrochloric acid-nitric acid polishing liquid. After polishing treatment, the high temperature resistance and corrosion protection effect of the copper protective agent on the copper workpiece can be further improved. Attached Figure Description

[0071] Figure 1 The figures show the actual images of the copper sheet samples in Example 1 and Comparative Examples 1-3 before and after baking at 110℃ for 12 hours. In the figures, A1-D1 are the actual images of Example 1 and Comparative Examples 1-3 before baking at 110℃ for 12 hours, and A2-D2 are the actual images of Example 1 and Comparative Examples 1-3 after baking at 110℃ for 12 hours.

[0072] Figure 2 The images show the unprotected copper sheet (A) in Comparative Example 1 and the copper sheet protected with the protective agent in Example 1 after being baked at 250°C for 6 hours (B, C).

[0073] Figure 3 The image shows the metallographic structure of the pure copper surface of the copper sheet protected with the protective agent in Example 2 at 50x magnification.

[0074] Figure 4 The image shows the metallographic structure of the pure copper surface of the copper sheet protected with the protective agent in Example 3 at 50x magnification.

[0075] Figure 5 The protective agent was prepared according to the formulations in Example 1 and Comparative Example 4. Detailed Implementation

[0076] This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiment.

[0077] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0078] A high-temperature resistant, anti-discoloration water-based copper protective agent, comprising the following components by weight percentage:

[0079]

[0080] The film-forming substance includes an aqueous solution of lithium silicate, sodium silicate, and sodium phosphate; the stabilizer includes an aqueous solution of phosphoric acid and an aqueous solution of boric acid; the thickener includes sodium polyacrylate; the leveling agent is a polyether-modified polysiloxane leveling agent; the wetting agent is a modified organosilicon wetting agent; and the corrosion inhibitor includes sodium molybdate.

[0081] The method of using the protective agent includes the following steps:

[0082] S1: Weigh the film-forming substance, stabilizer, thickener, leveling agent, wetting agent, and corrosion inhibitor according to the formula, and disperse them in deionized water to obtain a copper protectant;

[0083] S2: Immerse the copper workpiece in a copper protective agent at 5-40℃ for 30-90 seconds, then remove the residual solution from the surface of the copper workpiece and dry it.

[0084] In step S2, before immersing the copper workpiece in the copper protective agent, a pretreatment step is also included: the copper workpiece is treated in a polishing solution, then rinsed with deionized water and ultrasonicated, and then dried after ultrasonication.

[0085] The polishing solution is prepared by mixing sulfuric acid, hydrochloric acid, OY-110 pickling brightener, clean water, and any one of nitric acid or sodium nitrate solution in a volume ratio of 40:5:2:50-58:7 at a temperature of 5-40℃.

[0086] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0087] The copper workpieces in the following examples and comparative examples are made of pure copper sheets.

[0088] Example 1

[0089] The raw materials and their weight contents used in the protective agent of this embodiment are as follows: 60 ml of lithium silicate aqueous solution (solid content 23%), 5 g of sodium silicate, 1 g of sodium phosphate, 2 ml of phosphoric acid aqueous solution (mass fraction 38%-50%), 1 ml of boric acid aqueous solution (1 mol / L), 0.16 g of sodium polyacrylate, 0.2 g of leveling agent Flowsuper 2321 (polydimethylsiloxane copolymer co-modified with long-chain alkyl and polyether), 0.2 g of wetting agent 8241, 1 g of sodium molybdate, and 36 ml of water. In this embodiment, the film-forming substance content exceeds 60%, and it is diluted with water at a ratio of 1:1 before use.

[0090] The protective agent should be used according to the following steps:

[0091] (1) Copper pretreatment: The polished copper material is treated in polishing liquid and then rinsed and dried with deionized water (if the copper surface is free of oxides or organic protective layer, it can directly enter the closed immersion step).

[0092] (2) Use of protective agent

[0093] Mix the prepared protective agent with water in a 1:1 ratio and stir thoroughly until the protective agent becomes colorless and transparent.

[0094] Immerse the copper workpiece in the 5-40℃ range for 40 seconds, drain it after removal from the immersion tank, spin dry the remaining solution on the surface using a centrifuge, and dry it at 110℃ for 15 minutes.

[0095] The film formed in this embodiment exhibits excellent water irreversibility and good density. When the protected copper workpiece is baked in a muffle furnace at 250°C for 6 hours, the copper sheet shows no significant discoloration (e.g., ...). Figure 2 (As shown).

[0096] Example 2

[0097] (1) Preparation of protective agent

[0098] The raw materials and weight contents of the protective agent used in this embodiment are as follows: 30ml lithium silicate, 2.5g sodium silicate, 0.5g sodium phosphate, 1ml phosphoric acid, 0.5ml boric acid, 0.1g sodium polyacrylate, 0.2g Flowsuper 2330 (polyether modified polydimethylsiloxane), 0.2g 8241 wetting agent, 0.5g sodium molybdate, 68ml water, and the concentrations of lithium silicate, phosphoric acid, and boric acid are the same as in Example 1;

[0099] (2) Use of protective agent

[0100] Copper pretreatment: The polished copper material is treated in a polishing solution, then rinsed and dried with deionized water (if the copper surface is free of oxides or organic protective layers, it can directly proceed to the closed immersion step).

[0101] Immerse the copper workpiece in the 5-40℃ range for 30 seconds, drain it after removal from the immersion tank, spin dry the remaining solution on the surface using a centrifuge, and dry it at 110℃ for 15 minutes.

[0102] The formed protective layer exhibits excellent water irreversibility, good density, high temperature resistance, transparency, and colorfastness. When the protected copper sheet is baked in a muffle furnace at 250℃ for 6 hours, the copper sheet shows no obvious color change.

[0103] Example 3

[0104] (1) Preparation of protective agent

[0105] The raw materials and weight contents of the protective agent used in this embodiment are as follows: 36 ml lithium silicate, 3 g sodium silicate, 0.6 g sodium phosphate, 1 ml phosphoric acid, 0.5 ml boric acid, 0.1 g sodium polyacrylate, 0.1 g leveling agent Flowsuper 2321 (long-chain alkyl and polyether co-modified polydimethylsiloxane copolymer), 0.2 g 8241 wetting agent, 0.5 g sodium molybdate, 62 ml water, and the concentrations of lithium silicate, phosphoric acid, and boric acid are the same as in Example 1;

[0106] (2) Use of protective agent

[0107] The copper workpiece is immersed in the solution between 5-40℃ for 60 seconds. After being removed from the tank, it is dripped dry and the residual solution on the surface is spun dry using a centrifuge. It is then dried at 60℃ for 10 minutes and then formed into a film at 110℃ for 15 minutes.

[0108] The formed protective layer exhibits excellent water irreversibility, good density, high temperature resistance, transparency, and colorfastness. When the protected copper sheet is placed in a muffle furnace at 200℃ and baked for 6 hours, the copper sheet shows no obvious color change.

[0109] Example 4

[0110] (1) Preparation of protective agent

[0111] The raw materials and weight contents of the protective agent used in this embodiment are as follows: 35ml lithium silicate, 3g sodium silicate, 0.4g sodium phosphate, 0.8ml phosphoric acid, 0.4ml boric acid, 0.1g sodium polyacrylate, 0.1g leveling agent Flowsuper 2321 (long-chain alkyl and polyether co-modified polydimethylsiloxane copolymer), 0.2g 8241 wetting agent, 0.5g sodium molybdate, 64ml water, and the concentrations of lithium silicate, phosphoric acid, and boric acid are the same as in Example 1;

[0112] (2) Use of protective agent

[0113] Immerse the copper workpiece in the 5-35℃ range for 60 seconds, drain it after removal from the immersion tank, spin dry the remaining solution on the surface using a centrifuge, and dry it at 110℃ for 20 minutes.

[0114] The formed protective layer exhibits excellent water irreversibility, good density, high temperature resistance, transparency, and colorfastness. When the protected copper sheet is placed in a muffle furnace at 200℃ and baked for 6 hours, the copper sheet shows no obvious color change.

[0115] Comparative Example 1

[0116] The copper sheet is left untreated.

[0117] Comparative Example 2

[0118] (1) Preparation of protective agent

[0119] This comparative example uses commercially available copper anti-discoloration agent A, JC-3000 copper protectant from Hubei Jinfeiang Technology Co., Ltd.

[0120] (2) Use of protective agent

[0121] The usage method is the same as in Example 1.

[0122] Comparative Example 3

[0123] (1) Preparation of protective agent

[0124] This comparative example uses commercially available copper anti-discoloration agent B, Dongguan Hill Metal Materials Co., Ltd., and Kaiton KD-8049 copper protectant.

[0125] (2) Use of protective agent

[0126] The usage method is the same as in Example 1.

[0127] like Figure 1 As shown, from left to right, the copper sheet is as follows: unprotected copper sheet in Comparative Example 1, copper sheet protected with protective agent in Example 1, copper sheet protected with commercially available copper anti-tarnishing agent A in Comparative Example 2, and copper sheet protected with commercially available copper anti-tarnishing agent B in Comparative Example 3. The first row shows the copper sheets before baking at 110°C, and the second row shows the copper sheets after baking at 110°C for 12 hours. Figure 1 As can be seen, after the copper sheet was protected with the protective agent of Example 1 of the present invention, the copper sheet did not show obvious color change after being baked at a high temperature of 110°C for 12 hours, while Comparative Examples 1-3 all showed discoloration. The high temperature resistance of the protective agent of the present invention is superior to that of water-based or organic copper protective agents on the market.

[0128] Figure 2 The image shows the actual copper sheet after baking at 250°C for 6 hours, compared to the unprotected copper sheet in Comparative Example 1 and the copper sheet protected with the protective agent in Example 1. Figure 2 It can be seen that after the copper workpiece is protected by the protective agent of Example 1 of the present invention, the copper workpiece can be baked at a high temperature of 250°C for 6 hours without obvious color change, and Comparative Example 1 has no obvious color change.

[0129] Figure 3 This is a metallographic image of the pure copper surface of the copper sheet protected with the protective agent in Example 2, magnified at 50x. Figure 4 The image shows the metallographic image of the pure copper surface of the copper sheet protected by the protective agent in Example 3 at 50x magnification. It can be seen from the image that after the protective agent is cured, a continuous and uniform film layer is formed on the surface of the workpiece. After curing, no local accumulation (protrusion height > 2 μm) or undissolved residue (particle size > 5 μm) is observed in the film layer.

[0130] Comparative Example 4

[0131] The difference between this comparative example and Example 1 is that sodium molybdate is replaced with an equal amount of sodium tungstate.

[0132] Figure 5 The protective agent (undiluted) prepared according to the formulations in Example 1 and Comparative Example 4, such as Figure 5 As shown, bottle 1 is Example 1 (using sodium molybdate), and bottle 2 is Comparative Example 4 (using sodium tungstate). It can be clearly observed that under high concentration conditions, the protective agent, sodium tungstate, as a corrosion inhibitor, does not dissolve sufficiently, and precipitation occurs in the solution after several days. This comparison demonstrates that sodium molybdate is key to achieving "high concentration formulation," while sodium tungstate leads to decreased concentration and poor dispersibility, failing to realize the economic advantages of this invention.

[0133] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-temperature resistant, anti-discoloration water-based copper protective agent, characterized in that, By mass percentage, it includes the following components:

2. The high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 1, characterized in that, The film-forming substance includes an aqueous solution of lithium silicate, sodium silicate, and sodium phosphate, wherein the mass ratio of the aqueous solution of lithium silicate, sodium silicate, and sodium phosphate is 55-75:3-7:0.5-1.5, and the solid content of the aqueous solution of lithium silicate is 20-25%.

3. The high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 1, characterized in that, The stabilizer comprises an aqueous solution of phosphoric acid and an aqueous solution of boric acid, wherein the volume ratio of the aqueous solution of phosphoric acid to the aqueous solution of boric acid is 1.5-2.5:0.5-1.5, wherein the mass fraction of the aqueous solution of phosphoric acid is 38%-50%, and the concentration of the aqueous solution of boric acid is 0.8-1.2 mol / L.

4. The high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 1, characterized in that, The thickener includes sodium polyacrylate, and the leveling agent is a polyether-modified polysiloxane leveling agent.

5. The high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 1, characterized in that, The wetting agent is a modified organosilicon wetting agent.

6. The high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 1, characterized in that, The corrosion inhibitor includes sodium molybdate.

7. A method of using the high-temperature resistant, anti-discoloration water-based copper protective agent according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Weigh the film-forming substance, stabilizer, thickener, leveling agent, wetting agent, and corrosion inhibitor according to the formula, and disperse them in deionized water to obtain a copper protectant; S2: Immerse the copper workpiece in a copper protective agent at 5-40°C for 30-90 seconds, then remove the residual solution from the surface of the copper workpiece and dry it.

8. The method of using the high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 7, characterized in that, In step S2, the residual solution on the surface of the copper workpiece is removed by drip drying or centrifugal drying. The centrifugal drying speed is 200-400 r / min. The drying temperature is 90-120℃ and the drying time is 10-30 min.

9. The method of using the high-temperature resistant, anti-discoloration water-based copper protective agent according to claim 7, characterized in that, In step S2, before immersing the copper workpiece in the copper protective agent, a pretreatment step is also included: the copper workpiece is treated in a polishing solution, then rinsed with deionized water and ultrasonicated, and then dried after ultrasonication. The polishing solution is prepared by mixing sulfuric acid, hydrochloric acid, OY-110 pickling brightener, clean water, and any one of nitric acid or sodium nitrate solution in a volume ratio of 40:5:2:50-58:7 at a temperature of 5-40℃. The duration of the ultrasound is 30-120 seconds, and the ultrasound power is 600W-1200W.

10. A copper workpiece containing a high-temperature resistant, colorfast, water-based copper protective layer, characterized in that, The invention includes a copper workpiece and a copper protective layer thereon. The copper protective layer is prepared on the copper workpiece using a high-temperature resistant, anti-discoloration water-based copper protective agent as described in any one of claims 1-6. The copper protective layer has a -Si-O-Si- network structure and a thickness of 1-2 μm.

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