Production process optimization method for limited control of harmful substances in electroplated bright silver product

Abstract

The invention relates to the technical field of silver electroplating, in particular to a production process optimization method for limiting and controlling harmful substances in a silver bright electroplating product, which comprises the following steps: pretreating by using a composite degreaser containing 3-8% of sodium hydroxide, polyether modified siloxane and sodium ethylene diamine tetra (methylene phosphonic acid), pickling, adding benzotriazole, and activating a mercapto-benzothiazole-containing accelerant; the electroplating solution contains 80-120 g / L of silver nitrate, 30-50 g / L of sodium thiosulfate, 5-15 g / L of ascorbic acid, 2-5 g / L of polyethylene glycol, 10-20 g / L of sodium citrate and 1-3 g / L of 2-amino-5-sulfydryl-1, 3, 4-thiadiazole, and alternating pulse current is adopted; in the post-treatment, a trivalent chromium passivation solution and nano silicon dioxide composite silane are used for sealing, and low-temperature plasma treatment is combined. Through the composite degreaser, the additive and alternating pulse current, harmful substances such as lead, cadmium and mercury are lower than the European Union RoHS standard, phthalate is smaller than 0.1%, the corrosion resistance is enhanced through nano-composite silane sealing, and hexavalent chromium is replaced by trivalent chromium passivation to reduce toxicity.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating process optimization and harmful substance control, and in particular to a production process optimization method for controlling the limit of harmful substances in electroplated bright silver products. Background Art

[0002] In modern industrial production, electroplated bright silver products are widely used in electronics, home appliances, automobiles, accessories and many other fields due to their excellent decorative properties, corrosion resistance and conductivity. However, with the increasing global environmental awareness and increasingly stringent environmental regulations in various countries, the limited control of harmful substances in electroplated bright silver products has become an important challenge facing the industry.

[0003] At present, there are still many problems in the production process of electroplating bright silver. Traditional electroplating solution formulas often use compounds containing heavy metals, such as silver nitrate and chromate. These substances may remain on the surface of the product or be released into the environment during the production process, posing a potential threat to human health and the ecological environment. For example, heavy metals such as lead, cadmium, and mercury are biologically toxic and can be enriched through the food chain, seriously endangering human health; hexavalent chromium is listed as a Class I carcinogen by the International Agency for Research on Cancer, and is highly irritating and carcinogenic to the skin and respiratory tract.

[0004] In terms of production technology, traditional electroplating parameter control is relatively extensive. The unreasonable setting of parameters such as current density, temperature, and pH value can easily lead to unstable coating quality and the inclusion of harmful substances. At the same time, the imperfection of post-processing technology, such as poor passivation and sealing treatment, cannot effectively block the migration and release of harmful substances. In addition, the existing process lacks real-time monitoring and dynamic control of harmful substances, making it difficult to ensure that products continue to meet environmental standards.

[0006] On the other hand, consumers have higher and higher requirements for the environmental performance of products, and green and safe electroplating products have become the mainstream trend in the market. Therefore, there is an urgent need for a production process optimization method that can effectively control the content of harmful substances in electroplated bright silver products and improve the environmental performance of products.

[0007] In the existing technology, although there are some studies and patents on electroplating process optimization, most of them focus on improving the performance of the coating, and there is a lack of systematic research on the control of harmful substances. For example, some patents reduce the use of certain harmful substances by improving the formula of the electroplating solution, but do not optimize the entire production process; although the adjustment of some process parameters improves the quality of the coating, the control effect on harmful substances is limited.

[0008] In summary, the existing bright silver electroplating production process has obvious deficiencies in the control of harmful substances, and cannot meet the increasingly stringent environmental protection laws and market demands. Therefore, the present invention provides a production process optimization method for controlling harmful substances in bright silver electroplating products, aiming to achieve effective control of harmful substances and improve the environmental performance and market competitiveness of products by optimizing the plating solution formula, controlling the electroplating process parameters, improving the post-processing steps, and introducing an online monitoring system. Summary of the invention

[0009] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a production process optimization method for controlling the limit of harmful substances in electroplated bright silver products.

[0010] (II) Technical solution A production process optimization method for limiting the control of harmful substances in electroplated bright silver products comprises the following steps: S1, pretreatment stage: first use a solution containing a composite degreasing agent to remove oil at 40-60°C for 5-10 minutes, wherein the composite degreasing agent is composed of 3-8% sodium hydroxide by mass, 2-6% non-ionic surfactant polyether modified siloxane, and 1-3% chelating agent sodium ethylenediaminetetramethylenephosphonate; then use a sulfuric acid solution with a volume fraction of 10-20%, and add 0.5-2g / L corrosion inhibitor benzotriazole, and pickle for 2-5 minutes; finally, use a hydrochloric acid solution with a concentration of 5-10g / L, and add 0.1-0.5g / L accelerator mercaptobenzothiazole at the same time, and activate for 1-3min. The accelerator accelerates the activation process of the substrate surface; the structural formula of the mercaptobenzothiazole is The following reactions occur during the activation process: Me represents the substrate metal to be plated; S2, optimization of plating solution formula: the plating solution includes the following components: silver nitrate: 80-120g / L; sodium thiosulfate: 30-50g / L; ascorbic acid: 5-15g / L; polyethylene glycol: 2-5g / L; sodium citrate: 10-20g / L; additive: 1-3g / L, the additive is 2-amino-5-mercapto-1,3,4-thiadiazole, which can form a stable adsorption film on the surface of the plated piece, inhibiting the co-deposition of harmful substances, and its structure is: The reaction formula is: Deionized water: the balance, wherein sodium thiosulfate and silver nitrate undergo a complex reaction, and the reaction formula is: Form a stable complex, reduce the presence of free silver ions, thereby reducing the precipitation rate of silver and improving the uniformity and stability of the coating; S3, electroplating process parameter control: During the electroplating process, alternating pulse current is used for electroplating, the pulse frequency is 100-500Hz, the duty cycle is 20-50%, the positive pulse current density is controlled at 0.5-2.0A / dm², the negative pulse current density is controlled at 0.1-0.5A / dm², the electroplating temperature is 25-35℃, the pH value is adjusted to 6.0-7.0, and the electroplating time is 15-30min. The alternating pulse current can effectively improve the crystal structure of the coating and reduce the inclusion of harmful substances; S4, post-treatment stage: After the electroplating is completed, use deionized water at 20-30°C for 2-5 minutes; then use a solution containing a passivator for passivation for 1-3 minutes. The passivator consists of 3-8g / L chromium nitrate, 1-3g / L oxalic acid and 0.5-2g / L sodium fluoride. The following reactions occur during the passivation process: The formed passivation film has good corrosion resistance and barrier effect on harmful substances. Finally, a solution containing a nano-composite silane coupling agent is used for sealing treatment for 3-8 minutes. The nano-composite silane coupling agent is composited with nano-silicon dioxide and gamma-aminopropyltriethoxysilane.

[0011] Preferably, 0.1-0.5 g / L of sodium dodecyl sulfate is added to the electroplating solution as a surfactant, which can reduce the surface tension of the plating solution and improve the surface quality of the plated layer.

[0012] Preferably, during the electroplating process, the plating solution is circulated and filtered in combination with ultrasonic oscillation, with an ultrasonic frequency of 20-40 kHz and a circulation flow rate of 5-10 L / min, so as to further improve the uniformity and stability of the plating solution and reduce the enrichment of harmful substances in the plating solution.

[0013] Preferably, after the passivation for 1-3 minutes in the S4 post-treatment stage, micro-arc oxidation treatment is also performed, the micro-arc oxidation voltage is 200-400V, and the treatment time is 5-15 minutes, which can form a ceramic oxide film on the surface of the plated part to enhance the protection against harmful substances.

[0014] Preferably, the nanocomposite silane coupling agent used in the sealing treatment is subjected to low-temperature plasma treatment after coating, with a plasma treatment power of 50-200W, a treatment time of 2-5min, and a treatment temperature of 30-60°C, which can improve the bonding force between the silane coupling agent and the surface of the plated part and enhance the sealing effect.

[0015] Preferably, in the preparation process of the electroplating solution, silver nitrate is first dissolved in deionized water, and then sodium thiosulfate, ascorbic acid, polyethylene glycol, sodium citrate and additives are added in sequence, stirred evenly, and then the pH value is adjusted to a specified range.

[0016] Preferably, the oil removal treatment in the pretreatment stage adopts ultrasonic assisted oil removal with an ultrasonic power of 100-300W, which can improve the oil removal efficiency and effect.

[0017] Preferably, the electroplating solution is filtered before use, with a filtering accuracy of 0.1-0.5 μm, so as to remove impurity particles in the plating solution and ensure the quality of the plating layer.

[0018] Preferably, during the entire production process, an online monitoring system is used to monitor the content of harmful substances in the plating solution in real time. When the content of harmful substances exceeds a set threshold, a plating solution purification device is automatically started for treatment. The plating solution purification device uses a combination of ion exchange resin and activated carbon adsorption.

[0019] Preferably, the contents of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in the electroplated bright silver product are all lower than the limit values ​​specified in EU RoHS Directive 2011 / 65 / EU and its amending Directive (EU) No. 2015 / 863, and the content of phthalates is less than 0.1%.

[0020] 3. Beneficial technical effects Compared with the prior art, the present invention has the following beneficial effects: 1. By optimizing the plating solution formula and using composite degreasing agents and nitrogen-containing heterocyclic compound additives, the use and residue of harmful substances are reduced. Sodium thiosulfate forms a stable complex with silver nitrate, which reduces the concentration of free silver ions and the precipitation rate of silver, thereby reducing the co-deposition of other harmful substances. The additives form an adsorption film on the surface of the plated parts, which inhibits the co-deposition of harmful substances. The content of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in the products are all lower than the limit values ​​specified in the EU RoHS Directive, and the content of phthalates is less than 0.1%.

[0021] 2. The use of alternating pulse current for electroplating improves the crystal structure of the coating, improves the density and corrosion resistance of the coating. The use of pulse current makes the coating more uniform and delicate, reduces the pores and defects in the coating, thereby enhancing the decorativeness and functionality of the product.

[0022] 3. During the entire production process, the emission of harmful substances and environmental pollution are reduced by using environmentally friendly chemical reagents, optimizing process parameters and improving post-processing steps. The passivation agent uses trivalent chromium salt instead of hexavalent chromium, which greatly reduces the use of carcinogens in the passivation process; the use of nano-composite silane coupling agent enhances the sealing effect and reduces the migration and release of harmful substances.

[0023] 4. The application of technologies such as ultrasonic assisted oil removal, circulation filtration combined with ultrasonic oscillation has improved the oil removal efficiency and the uniformity of the plating solution, shortened the production time, and the introduction of the online monitoring system has realized real-time monitoring of the content of harmful substances in the plating solution, timely discovered and dealt with problems, avoided the production of unqualified products, and improved production efficiency and product qualification rate.

[0024] 5. By optimizing process parameters and using environmentally friendly chemical reagents, the waste of raw materials and subsequent processing costs are reduced. The amount of additives used is small, but the effect is significant, which reduces the cost of electroplating solution; the application of online monitoring system reduces the rework cost caused by unqualified products.

[0025] 6. The electroplated bright silver products produced by the present invention comply with the requirements of EU RoHS and REACH regulations, can smoothly enter the international market, and enhance the market competitiveness of the products. Meanwhile, the environmental performance and high quality of the products also meet the needs of consumers for green and safe products, and help enterprises establish a good brand image. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a production process optimization method; Figure 2 is the fitting curve of the corrosion degree of the embodiment and the comparative example changing with the salt spray test time (h); Figure 3 It is a bar chart comparing the production efficiency of the embodiment and the comparative example. DETAILED DESCRIPTION

[0027] Example 1 Degreasing treatment in the pretreatment stage: Immerse the substrate to be plated in a composite degreasing agent solution consisting of 3-8% sodium hydroxide, 2-6% polyether modified siloxane and 1-3% sodium ethylenediaminetetramethylenephosphonate. Treat at 40-60°C for 5-10 minutes, during which ultrasonic assisted degreasing is used with an ultrasonic power of 100-300W to improve degreasing efficiency and effect.

[0028] Pickling treatment: Place the degreased substrate in a 10-20% sulfuric acid solution, add 0.5-2g / L benzotriazole as a corrosion inhibitor, and treat for 2-5 minutes to remove the oxide film and impurities on the substrate surface.

[0029] Activation treatment: Immerse the pickled substrate in a hydrochloric acid solution with a concentration of 5-10g / L, and add 0.1-0.5g / L of mercaptobenzothiazole as an accelerator for 1-3min. Preparation of electroplating solution The formula of the electroplating solution is as follows: 80-120g / L silver nitrate, 30-50g / L sodium thiosulfate, 5-15g / L ascorbic acid, 2-5g / L polyethylene glycol, 10-20g / L sodium citrate, 1-3g / L additive (2-amino-5-mercapto-1,3,4-thiadiazole), and the balance is deionized water. During the electroplating process, alternating pulse current is used for electroplating. The pulse frequency is 100-500Hz, the duty cycle is 20-50%, the positive pulse current density is controlled at 0.5-2.0A / dm², the negative pulse current density is controlled at 0.1-0.5A / dm², the electroplating temperature is 25-35℃, the pH value is adjusted to 6.0-7.0, and the electroplating time is 15-30min.

[0030] Post-treatment stage water washing treatment: After the electroplating is completed, the plated parts are washed with deionized water. The water temperature is controlled at 20-30℃ and the washing time is 2-5min to remove the residual plating solution on the surface of the plated parts.

[0031] Passivation treatment: Immerse the washed plated parts in a passivation solution consisting of 3-8 g / L chromium nitrate, 1-3 g / L oxalic acid and 0.5-2 g / L sodium fluoride for 1-3 min.

[0032] Sealing treatment: immerse the passivated plated parts in a solution containing a nano-composite silane coupling agent, which is a compound of nano-silicon dioxide and γ-aminopropyltriethoxysilane, for 3-8 minutes. After coating, perform low-temperature plasma treatment, with a plasma treatment power of 50-200W, a treatment time of 2-5 minutes, and a treatment temperature of 30-60°C.

[0033] Test results After testing, the contents of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in the electroplated bright silver product produced in Example 1 are all lower than the limits specified in EU RoHS Directive 2011 / 65 / EU and its revised Directive (EU) No. 2015 / 863, and the content of phthalates is less than 0.1%. The density and corrosion resistance of the coating are significantly improved, and the surface is uniform and fine without obvious defects.

[0034] Example 2 Pretreatment stage oil removal treatment: Similar to Example 1, but the mass fraction of sodium hydroxide in the composite oil remover is 5%, polyether modified siloxane is 4%, and sodium ethylenediaminetetramethylenephosphonate is 2%. The treatment is carried out at 50°C for 8 minutes, and ultrasonic assisted oil removal is also used, with an ultrasonic power of 200W.

[0035] Pickling treatment: the volume fraction of sulfuric acid solution is 15%, the amount of benzotriazole added is 1g / L, and the treatment time is 3min. Activation treatment: the concentration of hydrochloric acid solution is 8g / L, the amount of mercaptobenzothiazole added is 0.3g / L, the treatment time is 2min, the concentration of silver nitrate prepared in the plating solution is 100g / L, sodium thiosulfate is 40g / L, ascorbic acid is 10g / L, polyethylene glycol is 3g / L, sodium citrate is 15g / L, and the additive is 2g / L; the electroplating process pulse frequency is 300Hz, the duty cycle is 30%, the positive pulse current density is 1.0A / dm², the negative pulse current density is 0.3A / dm², the electroplating temperature is 30℃, the pH value is 6.5, and the electroplating time is 20min.

[0036] Post-treatment stage: water washing: water temperature 25℃, washing time 3min.

[0037] Passivation treatment: the concentration of chromium nitrate is 5g / L, oxalic acid is 2g / L, sodium fluoride is 1g / L, and the treatment time is 2min.

[0038] Sealing treatment: the mass fraction of nano-silica is 10%, the concentration of γ-aminopropyltriethoxysilane is 3 g / L, and the treatment time is 5 min; the low-temperature plasma treatment power is 100 W, and the treatment time is 3 min.

[0039] Test results The harmful substance content of the electroplated bright silver product produced in Example 2 also complies with the EU RoHS standard, the coating quality is good, the surface is smooth, and the corrosion resistance and conductivity reach a high level.

[0040] Example 3 Degreasing treatment in the pretreatment stage: the mass fraction of sodium hydroxide in the composite degreasing agent is 8%, polyether-modified siloxane is 6%, and sodium ethylenediaminetetramethylenephosphonate is 3%; the treatment is carried out at 60°C for 10 minutes, and the ultrasonic power is 300W.

[0041] Pickling treatment: the volume fraction of sulfuric acid solution is 20%, the addition amount of benzotriazole is 2g / L, and the treatment time is 5min.

[0042] Activation treatment: The concentration of hydrochloric acid solution is 10g / L, the amount of mercaptobenzothiazole added is 0.5g / L, and the treatment time is 3min. The concentration of silver nitrate prepared in the plating solution is 120g / L, sodium thiosulfate is 50g / L, ascorbic acid is 15g / L, polyethylene glycol is 5g / L, sodium citrate is 20g / L, and the additive is 3g / L. The electroplating process pulse frequency is 500Hz, the duty cycle is 50%, the positive pulse current density is 2.0A / dm², the negative pulse current density is 0.5A / dm², the electroplating temperature is 35℃, the pH value is 7.0, and the electroplating time is 30min.

[0043] Post-treatment stage: water washing: water temperature 30℃, washing time 5min.

[0044] Passivation treatment: the concentration of chromium nitrate is 8g / L, oxalic acid is 3g / L, sodium fluoride is 2g / L, and the treatment time is 3min.

[0045] Sealing treatment: the mass fraction of nano-silica is 15%, the concentration of γ-aminopropyltriethoxysilane is 5g / L, and the treatment time is 8min; the low-temperature plasma treatment power is 200W, and the treatment time is 5min.

[0046] The test results show that the harmful substance content of the electroplated bright silver products produced in Example 3 is lower than the EU RoHS standard, and the density and corrosion resistance of the coating are further improved, which can meet higher application requirements.

[0047] Comparative Example Oil removal in the pretreatment stage: Use traditional sodium hydroxide solution with a concentration of 10 g / L at 50°C for 10 min without using ultrasonic assisted oil removal.

[0048] Pickling treatment: Use a sulfuric acid solution with a volume fraction of 15%, without adding corrosion inhibitor, and the treatment time is 5 minutes.

[0049] Activation treatment: using 8g / L hydrochloric acid solution, without adding accelerator, the treatment time is 5min. The plating solution contains only 100g / L silver nitrate, 40g / L sodium thiosulfate, 10g / L ascorbic acid, 3g / L polyethylene glycol, 15g / L sodium citrate, without adding additives. The electroplating process uses direct current for electroplating, the current density is 1.0A / dm², the electroplating temperature is 30℃, the pH value is 6.5, and the electroplating time is 30min.

[0050] Post-treatment stage Water washing treatment: water temperature 25℃, water washing time 5min. Passivation treatment: use traditional hexavalent chromium passivation solution (potassium dichromate concentration 10g / L), treatment time 5min.

[0051] Sealing treatment: using common silane coupling agent solution with a concentration of 3 g / L and a treatment time of 5 min, without low-temperature plasma treatment.

[0052] The test results show that the hexavalent chromium content in the electroplated bright silver product produced in the comparative example is 800 mg / kg, exceeding the 600 mg / kg limit stipulated in the EU RoHS Directive; the phthalate content is 0.2%, also exceeding the limit of 0.1%; there are obvious defects on the surface of the coating, the density and corrosion resistance are poor, and the conductivity is not as good as the embodiment product.

[0053] By comparing the above embodiments and comparative examples, it can be seen that the production process optimization method for limiting harmful substances in electroplated bright silver products of the present invention has significant advantages in harmful substance control, coating quality, environmental protection performance, etc., and can effectively meet the requirements of modern industrial production for environmental protection and product performance.

[0054] Coating performance comparison table: Compare Projects Example 1 Example 2 Example 3 Comparative Example Coating thickness (μm) 15 16 17 14 Porosity (pcs / cm²) 2 3 4 10 Salt spray test time (h) 500 480 450 300 Adhesion (cross-hatch method) Level 0 Level 0 Level 0 Level 2 Conclusion: The coating thickness of the embodiment is thicker, the porosity is lower, the salt spray test time is significantly extended, and the adhesion reaches the highest level 0 standard. The coating performance of the comparative example is obviously poor, the porosity is high, the salt spray test time is short, and the adhesion is also low, indicating that the process of the present invention can effectively improve the quality and corrosion resistance of the coating.

[0055] Comparison table of harmful substances content: Test items Example 1 Example 2 Example 3 Comparative Example Lead (mg / kg) ND ND ND ND Cadmium (mg / kg) ND ND ND ND Mercury (mg / kg) ND ND ND ND Hexavalent chromium (mg / kg) ND ND ND 800 Polybrominated biphenyls (mg / kg) ND ND ND ND Polybrominated diphenyl ethers (mg / kg) ND ND ND ND Phthalate esters (%) 0.05 0.06 0.07 0.2 Conclusion: Lead, cadmium, mercury, polybrominated biphenyls and polybrominated diphenyl ethers were not detected in the examples, and the contents of hexavalent chromium and phthalates were far below the limits of the EU RoHS directive. The contents of hexavalent chromium and phthalates in the control examples exceeded the standards by 33% and 100%, respectively, indicating that the control effect of the process of the present invention on harmful substances is significantly better than that of the traditional process.

[0056] Production efficiency and cost comparison table: Compare Projects Example 1 Example 2 Example 3 Comparative Example Production cycle (h) 1.5 1.6 1.8 2.5 Raw material cost (yuan / piece) 2.5 2.6 2.7 2.0 Pass rate (%) 98 97 96 90 Conclusion: The production cycle of the embodiment is shortened by 28%-40% compared with the traditional process. Although the cost of raw materials is slightly increased, the qualified rate is increased by 6-8 percentage points. In summary, the process of the present invention significantly improves production efficiency while ensuring product quality, and has obvious comprehensive cost advantages.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A production process optimization method for limiting the control of harmful substances in electroplated bright silver products, characterized by: The following steps are involved: S1, pretreatment stage: first use a solution containing a composite degreasing agent to remove oil at 40-60°C for 5-10 minutes, wherein the composite degreasing agent is composed of 3-8% sodium hydroxide by mass, 2-6% nonionic surfactant polyether modified siloxane, and 1-3% chelating agent sodium ethylenediaminetetramethylenephosphonate; then use a sulfuric acid solution with a volume fraction of 10-20%, and add 0.5-2g / L corrosion inhibitor benzotriazole, and pickle for 2-5 minutes; finally, use a hydrochloric acid solution with a concentration of 5-10g / L, and add 0.1-0.5g / L accelerator mercaptobenzothiazole, and activate for 1-3 minutes; S2, plating solution formula optimization: The plating solution includes the following components: Silver nitrate: 80-120g / L; Sodium thiosulfate: 30-50g / L; Ascorbic acid: 5-15g / L; Polyethylene glycol: 2-5g / L; sodium citrate: 10-20g / L; additive: 1-3g / L, the additive is 2-amino-5-mercapto-1,3,4-thiadiazole, which can form a stable adsorption film on the surface of the plated part, in which sodium thiosulfate and silver nitrate undergo a complex reaction; S3, electroplating process parameter control: During the electroplating process, alternating pulse current is used for electroplating, the pulse frequency is 100-500Hz, the duty cycle is 20-50%, the positive pulse current density is controlled at 0.5-2.0A / dm², the negative pulse current density is controlled at 0.1-0.5A / dm², the pH value is adjusted to 6.0-7.0, and the electroplating time is 15-30min; S4 post-treatment stage: after the electroplating is completed, use deionized water at 20-30°C for washing time of 2-5 minutes; then use a solution containing a passivator for passivation for 1-3 minutes, the passivator is composed of 3-8g / L chromium nitrate, 1-3g / L oxalic acid and 0.5-2g / L sodium fluoride, and finally use a solution containing a nano-composite silane coupling agent for sealing treatment for 3-8 minutes, the nano-composite silane coupling agent is a composite of nano-silicon dioxide and γ-aminopropyltriethoxysilane.

2. The production process optimization method according to claim 1, characterized in that: 0.1-0.5 g / L of sodium dodecyl sulfate is also added into the electroplating solution as a surfactant.

3. The production process optimization method according to claim 1, characterized in that: During the electroplating process, the plating solution is circulated and filtered in combination with ultrasonic oscillation, and the ultrasonic frequency is 20-40kHz and the circulation flow rate is 5-10L / min.

4. The production process optimization method according to claim 1, characterized in that: After the passivation of the S4 post-treatment stage for 1-3 minutes, micro-arc oxidation treatment is performed, and the micro-arc oxidation voltage is 200-400V and the treatment time is 5-15 minutes.

5. The production process optimization method according to claim 1, characterized in that: The nano composite silane coupling agent is subjected to low temperature plasma treatment after coating, and the plasma treatment power is 50-200W, the treatment time is 2-5min, and the treatment temperature is 30-60°C.

6. The production process optimization method according to claim 1, characterized in that: In the preparation process of the electroplating solution, silver nitrate is first dissolved in deionized water, and then sodium thiosulfate, ascorbic acid, polyethylene glycol, and sodium citrate are added in sequence, mixed evenly, and the pH value is adjusted to a specified range.

7. The production process optimization method according to claim 1, characterized in that: The oil removal treatment in the pretreatment stage adopts ultrasonic assisted oil removal, and the ultrasonic power is 100-300W.

8. The production process optimization method according to claim 1, characterized in that: The electroplating solution is filtered before use, and the filtering accuracy is 0.1-0.5 μm.

9. The production process optimization method according to claim 1, characterized in that: During the entire production process, an online monitoring system is used to monitor the content of harmful substances in the plating solution in real time. When the content of harmful substances exceeds the set threshold, the plating solution purification device is automatically started for treatment. The plating solution purification device uses a combination of ion exchange resin and activated carbon adsorption.

10. The production process optimization method according to claim 1, characterized in that: The contents of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers in the electroplated bright silver products are all below the limit values, and the content of phthalates is less than 0.1%.

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