High-adhesion plastic electroplating green surface treatment method

Abstract

The invention relates to the technical field of environment-friendly plastic electroplating, and discloses a green electroplating surface treatment method which comprises the steps of preparation of a green electroplating solution, a low-energy-consumption electrochemical electroplating process and a nanoparticle and photocatalyst link. The green electroplating solution utilizes a biomineralization material and a non-toxic metal compound, solves the problem of toxic metal pollution in a traditional electroplating process, and meets strict environmental protection requirements. And meanwhile, through an electrochemical electroplating process with low current density and temperature, high-adhesion electroplating is realized under the condition of relatively low energy consumption, and the production energy consumption and cost are greatly reduced. Under the background of increasing raw material and energy cost, the requirements of the market on environment-friendly and harmless materials are met. In addition, the adhesion, the wear resistance and the corrosion resistance of an electroplated layer are further enhanced by combining photocatalysis and a nano-particle technology.

Description

Technical Field

[0001] The invention relates to the technical field of environmentally friendly plastic electroplating, and in particular to a high-adhesion plastic electroplating green surface treatment method. Background Art Plastic electroplating is a technology commonly used to improve the adhesion, wear resistance and appearance of plastic surfaces. It is widely used in automotive exteriors, electrical housings and consumer electronics. Its basic working principle is to deposit a metal coating on the plastic surface through an electrochemical reaction. In order to ensure the adhesion of the electroplated layer, it is usually necessary to increase the surface roughness of the plastic substrate through plasma treatment, laser etching or chemical treatment. In addition, traditional electroplating solutions often use chemicals containing harmful metals (such as lead, cadmium, chromium, etc.), which may cause serious harm to the environment and human health during the electroplating process.

[0002] At present, the industry usually adopts the following methods to solve the adhesion and environmental protection problems in the process of plastic electroplating: On the one hand, the use of traditional electroplating solutions can better ensure the adhesion and stability of the electroplated layer, but it has major problems in environmental protection. Heavy metal pollution, difficulties in wastewater treatment and other problems have become technical bottlenecks faced by the electroplating industry. On the other hand, environmentally friendly electroplating solutions have gradually been proposed and have made certain progress, but these solutions often cannot meet the requirements of high adhesion and high coating stability at the same time, resulting in limited promotion in applications.

[0003] In addition, traditional electroplating processes usually need to be carried out under high temperature and high current conditions to ensure the adhesion and uniformity of the metal layer, which not only increases energy consumption but may also cause damage or deformation of the plastic substrate. In order to reduce energy consumption, the industry has tried to use low temperature and low current electrochemical plating methods, but these methods often fail to achieve ideal results in terms of adhesion and coating quality. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a high-adhesion plastic electroplating green surface treatment method in view of the defects existing in the above-mentioned prior art, so as to solve the problems of unstable adhesion, high energy consumption and catalyst aging proposed in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a high-adhesion plastic electroplating green surface treatment method, characterized in that it includes the following steps: Step 1, pretreatment of the surface of the plastic substrate: first, the plastic surface is treated by plasma treatment or laser etching. The method generates a microstructure on the plastic surface to increase the surface roughness for improving the adhesion between the electroplating layer and the plastic substrate during the electroplating process. The roughness of the plastic surface after the pretreatment is Ra 0.2 to 2.0 µm. Step 2, preparation of green electroplating solution: preparing a non-toxic and environmentally friendly electroplating solution, wherein the electroplating solution contains environmentally friendly metal ions, wherein the environmentally friendly metal ions are non-toxic compounds of copper, zinc or nickel, and the electroplating solution does not contain harmful heavy metals, the pH value of the electroplating solution is adjusted to 6.5 to 7.0, the concentration of environmentally friendly metal ions ranges from 0.1 to 0.5 mol / L, and the electroplating solution also includes a biomineralization material for enhancing the adhesion and stability of the electroplating layer, and the amount of the biomineralization material added is 0.5% to 5% of the total solution; Step 3, low energy consumption electrochemical plating: immersing the pretreated plastic substrate in the green electroplating solution prepared above, and electroplating is performed using a low current density electrochemical plating process, wherein the current density is 0.1 A / dm² to 0.5 A / dm², the plating temperature is 20°C to 60°C, and the plating time is 5 to 30 minutes; Step 4, adding nanoparticles: adding nanoparticles to the above electroplating solution, wherein the nanoparticles are selected from nanosilver, nanographene and / or nanotitanium dioxide, and the mass ratio of the nanoparticles is 0.5% to 5% of the total amount of the electroplating solution to enhance the adhesion, wear resistance and corrosion resistance of the electroplating layer; Step 5, photocatalytic enhancement: during the electroplating process, a photocatalyst is added, wherein the photocatalyst is a titanium-based photocatalytic material, and the amount of the photocatalyst added is 0.1% to 1% of the total amount of the electroplating solution; during the electroplating process, the photocatalyst is activated by light, promotes the electroplating reaction, accelerates the reduction of metal ions, and further improves the adhesion and stability of the electroplating layer; Step 6, curing and post-treatment of the electroplating layer: After the electroplating is completed, the electroplating layer is heat-treated and cured by heating the electroplating layer to 80°C to 150°C and maintaining it for 10 to 30 minutes to enhance the hardness and adhesion of the electroplating layer; at the same time, it is washed and dried to remove the residual chemicals in the electroplating process to ensure the purity of the electroplating layer.

[0006] Step 7, wastewater recovery and metal reuse: During the electroplating process, the electroplating wastewater is recovered and treated using electrochemical reduction and membrane separation technology. The metal ions in the wastewater are recovered and purified to ensure that the metal concentration in the wastewater is lower than the environmental emission standard, and the recovered metal ions are added back into the electroplating solution for recycling.

[0007] As a further embodiment of the present invention, the plasma treatment method is carried out by low-temperature plasma or atmospheric plasma treatment, wherein the treatment temperature of the low-temperature plasma is 20°C to 50°C, and the treatment time is 10 to 30 seconds.

[0008] As a further solution of the present invention, the laser etching method uses a laser with a wavelength of 500 to 1000 nm to generate tiny pits on the plastic surface by focusing the laser beam. The laser power is 0.5W to 5W and the laser scanning speed is 1mm / s to 10mm / s.

[0009] As a further embodiment of the present invention, the environmentally friendly metal ions of the electroplating solution are non-toxic compounds, including but not limited to copper chloride, zinc chloride or nickel chloride, and the total metal concentration of the electroplating solution ranges from 0.1 mol / L to 0.5 mol / L.

[0010] As a further embodiment of the present invention, the biomineralization material is a mineral salt of natural origin, the mineralization components contained in the biomineralization material are selected from calcium, magnesium or phosphate, and the biomineralization material is dissolved in the electroplating solution to ensure that the concentration of the biomineralization material is in the range of 0.5% to 5% by weight.

[0011] As a further embodiment of the present invention, the current density in the low current density electrochemical plating process is 0.1 A / dm² to 0.3 A / dm², the plating temperature is 25°C to 40°C, and the plating time is 10 to 20 minutes.

[0012] As a further embodiment of the present invention, the nanoparticles are a mixture of nanosilver, nanographene and / or nanotitanium dioxide, and the particle size of the nanoparticles is 10 to 100 nm, and the mass ratio of the nanoparticles is 0.5% to 3% of the total amount of the electroplating solution.

[0013] As a further solution of the present invention, the photocatalyst is a titanium-based photocatalytic material, the titanium-based photocatalyst contained therein is sodium titanate or titanium dioxide, and the added amount of the photocatalyst is 0.1% to 0.5% of the total amount of the electroplating solution.

[0014] As a further embodiment of the present invention, the heat treatment temperature in the electroplating layer curing and post-treatment steps is 90°C to 120°C, and the holding time is 15 to 25 minutes.

[0015] As a further embodiment of the present invention, the wastewater treatment method in the wastewater recovery and metal reuse step includes an electrochemical reduction method and a membrane separation technology. The electrochemical reduction method is used to reduce metal ions in the wastewater, and the metal ions are extracted and recovered from the wastewater by the membrane separation technology.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: With increasingly stringent global environmental regulations, especially the increasing environmental protection requirements of the European and Asian markets for the automotive, consumer electronics and home appliance industries, how to ensure that plastic electroplating does not pollute the environment while meeting high adhesion has become a difficult problem to be solved by major manufacturing companies. The green electroplating solution of the present invention eliminates the problem of using toxic heavy metals in the traditional electroplating process by utilizing biomineralized materials and non-toxic metal compounds, which meets the urgent demand for environmentally friendly and harmless materials in the market. Through a low-energy electrochemical plating process, high-adhesion electroplating can be achieved under lower current density and temperature conditions, greatly reducing production energy consumption and costs. In the context of rising prices of raw materials and energy, it not only meets the industry's urgent demand for low-cost production, but also effectively enhances the market competitiveness of enterprises. By combining photocatalysis and nanoparticles, the adhesion, wear resistance and corrosion resistance of the electroplating layer are improved; in the specific implementation, the biomineralized materials interact with metal ions to enhance the adhesion and stability of the electroplating layer, that is, the mineralized materials promote the more uniform deposition of metal ions on the plastic surface by forming microstructures and crystal nuclei during the electroplating process, thereby improving the structural density and adhesion of the metal coating; lower current density helps the metal ions to deposit evenly on the plastic surface, avoiding uneven deposition or damage to the plastic substrate caused by excessive current. Under low temperature conditions, metal ions can still be effectively reduced and deposited, and can reduce energy waste and substrate deformation caused by high temperature; the two-dimensional structure of nanoparticles such as graphene can significantly enhance the corrosion resistance of the electroplating layer, while nanosilver enhances the antibacterial and wear resistance of the electroplating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 It is a schematic diagram of the green electroplating technology process of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1In an embodiment of the present invention, a high-adhesion plastic electroplating green surface treatment method is characterized by comprising the following steps: Step 1, pretreatment of the surface of the plastic substrate: first, the plastic surface is treated by plasma treatment or laser etching. The method generates a microstructure on the plastic surface to increase the surface roughness for improving the adhesion between the electroplating layer and the plastic substrate during the electroplating process. The roughness of the plastic surface after the pretreatment is Ra 0.2 to 2.0 µm. Step 2, preparation of green electroplating solution: preparing a non-toxic and environmentally friendly electroplating solution, wherein the electroplating solution contains environmentally friendly metal ions, wherein the environmentally friendly metal ions are non-toxic compounds of copper, zinc or nickel, and the electroplating solution does not contain harmful heavy metals, the pH value of the electroplating solution is adjusted to 6.5 to 7.0, the concentration of environmentally friendly metal ions ranges from 0.1 to 0.5 mol / L, and the electroplating solution also includes a biomineralization material for enhancing the adhesion and stability of the electroplating layer, and the amount of the biomineralization material added is 0.5% to 5% of the total solution; Step 3, low energy consumption electrochemical plating: immersing the pretreated plastic substrate in the green electroplating solution prepared above, and electroplating is performed using a low current density electrochemical plating process, wherein the current density is 0.1 A / dm² to 0.5 A / dm², the plating temperature is 20°C to 60°C, and the plating time is 5 to 30 minutes; Step 4, adding nanoparticles: adding nanoparticles to the above electroplating solution, wherein the nanoparticles are selected from nanosilver, nanographene and / or nanotitanium dioxide, and the mass ratio of the nanoparticles is 0.5% to 5% of the total amount of the electroplating solution to enhance the adhesion, wear resistance and corrosion resistance of the electroplating layer; In the present invention, the selection of nanoparticles and the proportion setting thereof play a vital role in improving the performance of the electroplating layer. According to different application requirements, a single type of nanoparticles can be selected, or multiple nanoparticles can be used in combination to optimize the comprehensive performance of the electroplating layer. Among them, the selection and proportion of nanoparticles follow the following principles, including the use of a single nanoparticle: Nanosilver: If the goal is to improve the conductivity and antibacterial properties of the electroplated layer, nanosilver particles are preferred. Nanosilver can provide excellent antibacterial function and wear resistance in the electroplated layer, and is suitable for applications that require corrosion protection and resistance to microbial invasion (such as medical devices, electronic components, etc.). Its use concentration can be 0.5% to 2% of the total electroplating solution.

[0021] Nanographene: If the mechanical strength, corrosion resistance and wear resistance of the electroplating layer are the main considerations, nanographene can be used alone. The high mechanical strength and oxidation resistance of graphene can effectively improve the surface hardness and corrosion resistance of the electroplating layer, and is suitable for applications such as automotive exterior parts and wear-resistant tools. Its usage concentration is 1% to 3% of the total electroplating solution.

[0022] Nano-titanium dioxide: Nano-titanium dioxide is mainly used to improve the UV resistance and durability of electroplating layers, especially in applications exposed to outdoor environments (such as electronic product housings). Its photocatalytic properties can improve the stability and aging resistance of the electroplating layer. The concentration can be 0.5% to 1% of the total electroplating solution.

[0023] And including the combination of multiple nanoparticles: When the electroplating layer needs to have multiple properties, you can choose to reasonably combine three nanoparticles. When used in combination, the proportion of different particles is adjusted according to specific needs: The preferred ratio is: the combination ratio of nano silver, nano graphene and nano titanium dioxide can be 0.5% to 2%, 0.5% to 3% and 0.3% to 1% (the ratio of each nano particle can be optimized according to the performance requirements of the electroplating layer). For example, if it is necessary to improve the antibacterial property, wear resistance and UV aging resistance of the electroplating layer at the same time, it can be used in combination according to such a ratio.

[0024] In this optimized combination, the combination of nanosilver and nanographene can enhance the antibacterial and mechanical strength of the electroplating layer. Silver particles provide antibacterial and corrosion resistance, and graphene provides excellent wear resistance and mechanical strength. The combination of the two can provide balanced performance in a variety of applications; the combination of nanosilver and nanotitanium dioxide can improve the antibacterial properties of the electroplating layer as well as its UV resistance and corrosion resistance. The photocatalytic effect of titanium dioxide combined with the antibacterial effect of silver particles is suitable for products exposed to harsh environments; the combination of nanographene and nanotitanium dioxide can improve the wear resistance, corrosion resistance and UV resistance of the electroplating layer. The strength and wear resistance of graphene combined with the photocatalytic and UV resistance of titanium dioxide can significantly enhance the durability of the electroplating layer. In practical applications, the specific choice of which nanoparticles to use and their combination ratio can be adjusted according to the specific functions required by the electroplating layer. For example, if the goal is to enhance the wear resistance and corrosion resistance of the electroplating layer, the proportion of nano-graphene and nano-silver can be increased; if the UV resistance of the electroplating layer is to be enhanced, the proportion of nano-titanium dioxide can be appropriately increased, which are all extended implementation methods known to ordinary technicians in this field.

[0025] Step 5, photocatalytic enhancement: during the electroplating process, a photocatalyst is added, wherein the photocatalyst is a titanium-based photocatalytic material, and the amount of the photocatalyst added is 0.1% to 1% of the total amount of the electroplating solution; during the electroplating process, the photocatalyst is activated by light, promotes the electroplating reaction, accelerates the reduction of metal ions, and further improves the adhesion and stability of the electroplating layer; Step 6, curing and post-treatment of the electroplating layer: After the electroplating is completed, the electroplating layer is heat-treated and cured by heating the electroplating layer to 80°C to 150°C and maintaining it for 10 to 30 minutes to enhance the hardness and adhesion of the electroplating layer; at the same time, it is washed and dried to remove the residual chemicals in the electroplating process to ensure the purity of the electroplating layer.

[0026] Step 7, wastewater recovery and metal reuse: During the electroplating process, the electroplating wastewater is recovered and treated using electrochemical reduction and membrane separation technology. The metal ions in the wastewater are recovered and purified to ensure that the metal concentration in the wastewater is lower than the environmental emission standard, and the recovered metal ions are added back into the electroplating solution for recycling.

[0027] As a further embodiment of the present invention, the plasma treatment method is carried out by low-temperature plasma or atmospheric plasma treatment, wherein the treatment temperature of the low-temperature plasma is 20°C to 50°C, and the treatment time is 10 to 30 seconds.

[0028] As a further solution of the present invention, the laser etching method uses a laser with a wavelength of 500 to 1000 nm to generate tiny pits on the plastic surface by focusing the laser beam. The laser power is 0.5W to 5W and the laser scanning speed is 1mm / s to 10mm / s.

[0029] As a further embodiment of the present invention, the environmentally friendly metal ions of the electroplating solution are non-toxic compounds, including but not limited to copper chloride, zinc chloride or nickel chloride, and the total metal concentration of the electroplating solution ranges from 0.1 mol / L to 0.5 mol / L.

[0030] As a further embodiment of the present invention, the biomineralization material is a mineral salt of natural origin, the mineralization components contained in the biomineralization material are selected from calcium, magnesium or phosphate, and the biomineralization material is dissolved in the electroplating solution to ensure that the concentration of the biomineralization material is in the range of 0.5% to 5% by weight.

[0031] As a further embodiment of the present invention, the current density in the low current density electrochemical plating process is 0.1 A / dm² to 0.3 A / dm², the plating temperature is 25°C to 40°C, and the plating time is 10 to 20 minutes.

[0032] As a further embodiment of the present invention, the nanoparticles are a mixture of nanosilver, nanographene and / or nanotitanium dioxide, and the particle size of the nanoparticles is 10 to 100 nm, and the mass ratio of the nanoparticles is 0.5% to 3% of the total amount of the electroplating solution.

[0033] As a further solution of the present invention, the photocatalyst is a titanium-based photocatalytic material, the titanium-based photocatalyst contained therein is sodium titanate or titanium dioxide, and the added amount of the photocatalyst is 0.1% to 0.5% of the total amount of the electroplating solution.

[0034] As a further embodiment of the present invention, the heat treatment temperature in the electroplating layer curing and post-treatment steps is 90°C to 120°C, and the holding time is 15 to 25 minutes.

[0035] As a further embodiment of the present invention, the wastewater treatment method in the wastewater recovery and metal reuse step includes an electrochemical reduction method and a membrane separation technology. The electrochemical reduction method is used to reduce metal ions in the wastewater, and the metal ions are extracted and recovered from the wastewater by the membrane separation technology.

[0036] Embodiment 1: In this embodiment, the green electroplating technology of the present invention is applied to electroplating the plastic substrate of the automobile exterior parts. First, the plastic surface is pre-treated by plasma treatment to increase the surface roughness to ensure that the subsequent electroplating layer can form a stronger adhesion with the plastic substrate. The surface roughness of the treated plastic reaches Ra 0.5 µm to adapt to the electroplating process with high adhesion requirements.

[0037] Next, electroplating is performed using the green electroplating solution provided by the present invention, wherein the solution is composed of non-toxic metal compounds (such as non-toxic salts of copper and zinc) and biomineralization materials, and the pH value is controlled within the range of 6.5 to 7.0. Unlike conventional solutions, the solution does not contain harmful heavy metals, and the addition of biomineralization materials enables metal ions to be more stably deposited on the plastic surface, thereby improving the adhesion and durability of the coating.

[0038] During the electroplating process, the present invention adopts low-energy electrochemical plating technology, controls the current density between 0.2 A / dm² and 0.4 A / dm², and maintains the electroplating temperature at about 40°C, which effectively reduces energy consumption and ensures the stability and adhesion of the coating. In order to further enhance the functionality of the electroplated layer, nanosilver particles are added to the electroplating solution to increase the wear resistance and corrosion resistance of the coating.

[0039] After the electroplating is completed, the electroplated layer is heat treated and cured, and the temperature is controlled at 120°C for 15 minutes to increase the hardness of the coating. Finally, wastewater recovery and metal recycling are carried out, and the metal ions in the wastewater are recovered by electrochemical reduction and membrane separation technology to ensure that the metal concentration in the wastewater is lower than the environmental protection standard, and the recovered metal is added to the electroplating solution for recycling.

[0040] Embodiment 2: In this embodiment, the plastic shell of the consumer electronics industry is selected for electroplating, specifically applied to the surface electroplating of the smartphone shell. First, the surface of the plastic shell is micro-processed by laser etching technology to create a uniformly distributed microscopic hole structure, and the surface roughness is increased to Ra 0.6 µm to ensure that the electroplating layer can be firmly attached. This pretreatment method not only enhances the surface adhesion, but also avoids the common problem of coating peeling.

[0041] Subsequently, electroplating is performed using the green electroplating solution provided by the present invention, which contains non-toxic compounds of copper, zinc and nickel and does not contain harmful heavy metals. This environmentally friendly solution adjusts the ion concentration of the solution through biomineralized materials, ensuring the stability and high adhesion of the solution while avoiding the pollution of the environment by toxic metals. The pH value of the solution is controlled at about 6.8, so that the metal ions can be more evenly deposited on the plastic surface.

[0042] The electroplating process uses a low-energy electrochemical plating process, with a current density of 0.3 A / dm², a plating temperature between 35°C and 45°C, and a duration of 15 minutes. This low-energy process not only reduces production costs but also improves plating efficiency. After the electroplating is completed, the electroplated layer is heat cured at 80°C to further improve the hardness and adhesion of the coating.

[0043] Experimental comparison shows that the adhesion of the plastic shell electroplated in this embodiment is about 35% higher than that of the shell processed by the traditional electroplating process, and the wear resistance and corrosion resistance of the electroplating layer are improved by 40%. This result shows that the combination of low-energy electrochemical plating process and green electroplating solution can significantly reduce energy consumption and environmental risks while ensuring high adhesion. In addition, the wastewater recovery system recovers the metal ions generated in the electroplating process through membrane separation technology, ensuring that the metal concentration in the wastewater is lower than the national environmental protection emission standard, and reusing the recovered metal to achieve the goal of resource recycling and environmental friendliness.

[0044] Example 3: In order to further improve the stability of the electroplating solution and the adhesion of the electroplated layer, a composite environmentally friendly metal ion is introduced in this example, including non-toxic compounds of copper, zinc and nickel, and the chemical ratio is optimized to ensure that the concentration of the metal ions in the electroplating process can achieve the best effect. By controlling the concentration range of the metal ions to 0.3 mol / L to 0.4 mol / L and adjusting the pH value to 6.8, uniform deposition of the metal ions is ensured.

[0045] In the green electroplating solution, biomineralized materials are added, which come from natural mineral salts. The selected mineralized components include calcium, magnesium and phosphate, and their concentration range is ensured to be 1% to 3% of the total solution. This adjustment can not only enhance the adhesion of the electroplated layer, but also improve its corrosion resistance and wear resistance. In this embodiment, a low current density electrochemical plating process is adopted, by adjusting the current density to 0.2A / dm² to 0.4A / dm², and controlling the electroplating temperature between 25°C and 35°C to reduce energy consumption in the production process, while ensuring the quality and adhesion of the electroplated layer. During the electroplating process, a longer electroplating time (20 to 25 minutes) is used to ensure the stability and uniformity of the electroplated layer, and a detailed post-treatment process is performed after the electroplating is completed to maximize the adhesion effect of the electroplated layer. In this embodiment, the selection and concentration of nanoparticles are further optimized, and the nanoparticles include a mixture of nanosilver, nanographene and nanotitanium dioxide, and the mass ratio of the solution is 1% to 3% of the total amount of the electroplating solution. The introduction of these nanoparticles can enhance the wear resistance and corrosion resistance of the electroplating layer and have good electrical properties.

[0046] In terms of photocatalysts, this embodiment uses titanium-based photocatalytic materials of sodium titanate and titanium dioxide, and the amount of photocatalyst added is maintained between 0.2% and 0.5%. Through light activation, the titanium-based photocatalyst can accelerate the reduction reaction of metal ions during the electroplating process, and further enhance the adhesion and stability of the electroplating layer. In terms of wastewater recovery, this embodiment adopts a treatment method that combines more efficient membrane separation technology and electrochemical reduction method, which can effectively reduce the metal concentration in the wastewater to below the environmental emission standards and ensure a high recovery rate of metal ions in the wastewater. For the recovered metal ions, more advanced reuse technology is used to add them back into the electroplating solution to form a closed-loop production system, thereby reducing the consumption of raw materials and reducing production costs. Its specific implementation steps: Step 1: Surface pretreatment of plastic substrate: The plastic substrate is pretreated by plasma or laser etching to ensure that the surface roughness is between Ra 0.3 and 1.0 μm to improve the adhesion of the electroplating layer.

[0047] Step 2: Preparation of green electroplating solution: Prepare an environmentally friendly electroplating solution containing copper, zinc and nickel, and add biomineralization materials and other additives to ensure that the pH value of the solution is in the range of 6.8 and the metal ion concentration is between 0.3mol / L and 0.4mol / L.

[0048] Step 3: Low energy electrochemical plating: Plating is carried out under the condition of controlled current density of 0.2A / dm² to 0.4A / dm², the plating temperature is maintained between 25°C and 35°C, and the time is 20 to 25 minutes.

[0049] Step 4: Nanoparticle and photocatalyst addition: 1% to 3% nanoparticles and 0.2% to 0.5% photocatalyst are added to the electroplating solution to enhance the functionality of the electroplating layer.

[0050] Step 5: Post-plating treatment: heat treatment curing and water washing treatment are carried out to ensure the adhesion and purity of the electroplating layer. The heat treatment temperature is 90°C to 120°C and the treatment time is 15 to 25 minutes.

[0051] Step 6: Wastewater recovery and metal reuse: Use membrane separation technology and electrochemical reduction to treat wastewater, recover metal ions and purify them to ensure that the metal concentration in the wastewater meets environmental protection standards.

[0052] The experimental results of this embodiment show that the adhesion of the electroplated layer after the above optimization treatment is improved by about 35% compared with the traditional method, and the wear resistance and corrosion resistance are improved by 40%. The metal ion recovery rate after wastewater recycling reaches more than 90%, which meets the national environmental protection emission standards.

[0053] Embodiment 4: In this embodiment, a plastic substrate is selected, and its surface is first pretreated by plasma treatment. The plasma treatment method uses atmospheric plasma, the treatment temperature is controlled at 40°C to 50°C, and the treatment time is 15 seconds. The treatment effectively increases the surface roughness to Ra 0.8 µm by generating microstructures (such as tiny holes and protrusions) on the plastic surface, so that the electroplating layer can form a stronger mechanical adhesion with the substrate. The surface of the treated plastic substrate shows stronger hydrophilicity and higher adhesion. Specifically, plasma treatment increases the surface polarity by forming surface free radicals, thereby enhancing the adhesion and stability of the electroplating layer.

[0054] The prepared green electroplating solution consists of non-toxic metal ions (non-toxic compounds of copper, zinc or nickel) and biomineralized materials. The non-toxic metal compounds used are copper chloride and zinc chloride, with a concentration range of 0.2 mol / L to 0.4 mol / L, and a pH value controlled between 6.8 and 7.0 to ensure solution stability and avoid contamination by harmful metals. On this basis, the biomineralized materials use natural mineral salts, and the mineralized components contained are mainly calcium, magnesium and phosphate, with a concentration controlled at 1.5% to 3% of the total solution. Biomineralized materials enhance the adhesion and stability of the electroplated layer by interacting with metal ions. Specifically, the mineralized materials promote the more uniform deposition of metal ions on the plastic surface by forming microstructures and crystal nuclei during the electroplating process, thereby improving the structural density and adhesion of the metal coating.

[0055] The pretreated plastic substrate is immersed in the above-mentioned green electroplating solution and electroplated using a low current density electrochemical plating process. The current density is 0.2 A / dm² to 0.4 A / dm², the electroplating temperature is controlled between 30°C and 40°C, and the electroplating time is 15 minutes. By optimizing the current density and electroplating temperature, this process not only reduces energy consumption, but also obtains a high-adhesion electroplating layer under lower energy conditions. The specific principle is that a lower current density helps the metal ions to deposit evenly on the plastic surface, avoiding uneven deposition or damage to the plastic substrate caused by excessive current. Under low temperature conditions, metal ions can still effectively reduce deposition, and can reduce energy waste and substrate deformation caused by high temperature.

[0056] Nanoparticles are added to the electroplating solution to enhance the wear resistance and corrosion resistance of the electroplated layer. The selection of nanoparticles includes a mixture of nanosilver, nanographene and nanotitanium dioxide, with a mass ratio of 2% of the total amount of the electroplating solution. The particle size of the nanoparticles is controlled between 10 and 50 nanometers. The selection of particle size helps to improve the compactness of the electroplated layer and enhance the corrosion resistance and wear resistance of the electroplated layer. Through experimental analysis, the nanoparticles are dispersed in the electroplated layer to form a stable composite structure, which improves the surface hardness and antioxidant capacity of the electroplated layer. Specifically, the two-dimensional structure of nanoparticles such as graphene can significantly enhance the corrosion resistance of the electroplated layer, while nanosilver enhances the antibacterial and wear resistance of the electroplated layer.

[0057] In order to further improve the adhesion and stability of the electroplating layer, a photocatalyst is added during the electroplating process. Titanium-based photocatalyst titanium dioxide is selected, and the addition amount is 0.3% of the total amount of the electroplating solution. The photocatalyst is activated by light, promotes the reduction reaction of metal ions, and accelerates the electroplating process. The experimental results show that titanium dioxide, as a photocatalyst, can effectively enhance the reduction ability of metal ions under ultraviolet light irradiation and increase the reduction reaction rate during the electroplating process, thereby making the electroplating layer denser and more adherent. In addition, the photocatalyst can also destroy harmful impurities in the electroplating solution, further improving the purity and stability of the electroplating layer.

[0058] After the electroplating is completed, the electroplated layer is immediately heat treated and cured. The electroplated part is heated to 120°C and maintained for 20 minutes to ensure that the hardness and adhesion of the electroplated layer meet the predetermined standards. During the heat treatment process, the metal crystal structure in the electroplated layer is further optimized and the adhesion is improved. After curing, water washing and drying are carried out to ensure that the residual chemicals in the electroplating process are removed to avoid affecting subsequent use. The specific principle of heat treatment is that high temperature promotes the grain growth of the metal coating, further enhances the cohesion of the metal, and improves the hardness and wear resistance of the electroplated layer.

[0059] The wastewater generated during the electroplating process is treated by electrochemical reduction and membrane separation technology to recover the metal ions in the wastewater. The recovered metal ions are purified and then added back to the electroplating solution for recycling. The experimental results show that the recovery rate of metal ions after wastewater treatment can reach more than 90%, ensuring that the metal concentration in the wastewater meets the environmental emission standards and greatly reduces the production cost. The principle of wastewater recycling is that the electrochemical reduction method reduces the metal ions in the wastewater to solid metals by applying electric current, and these metals are then extracted and purified by membrane separation technology to achieve the recycling of metals. Through the optimization treatment of this embodiment, the adhesion of the electroplating layer is improved by about 30% compared with the traditional method, and the corrosion resistance and wear resistance are improved by 40% and 50% respectively. In terms of wastewater recycling, the recovered metal ions are purified and then added back to the electroplating solution to meet the environmental emission standards, and the recovery rate exceeds 90%.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A high-adhesion plastic electroplating green surface treatment method, characterized in that: The following steps are involved: Step 1, pretreatment of the surface of the plastic substrate: first, the plastic surface is treated by plasma treatment or laser etching. The method generates a microstructure on the plastic surface to increase the surface roughness for improving the adhesion between the electroplating layer and the plastic substrate during the electroplating process. The roughness of the plastic surface after the pretreatment is Ra 0.2 to 2.0 µm. Step 2, preparation of green electroplating solution: preparing a non-toxic and environmentally friendly electroplating solution, wherein the electroplating solution contains environmentally friendly metal ions, wherein the environmentally friendly metal ions are non-toxic compounds of copper, zinc or nickel, the pH value of the electroplating solution is adjusted to 6.5 to 7.0, the concentration range of the environmentally friendly metal ions is 0.1 to 0.5 mol / L, and the electroplating solution also includes a biomineralization material for enhancing the adhesion and stability of the electroplating layer, and the amount of the biomineralization material added is 0.5% to 5% of the total solution; Step 3, low energy consumption electrochemical plating: immersing the pretreated plastic substrate in the green electroplating solution prepared above, and electroplating is performed using a low current density electrochemical plating process, with a current density of 0.1 A / dm² to 0.5 A / dm², an electroplating temperature of 20°C to 60°C, and an electroplating time of 5 to 30 minutes; Step 4, adding nanoparticles: adding nanoparticles to the above electroplating solution, wherein the nanoparticles are selected from nanosilver, nanographene and / or nanotitanium dioxide, and the mass ratio of the nanoparticles is 0.5% to 5% of the total amount of the electroplating solution; Step 5, photocatalytic enhancement: during the electroplating process, adding a photocatalyst, wherein the photocatalyst is a titanium-based photocatalytic material, and the amount of the photocatalyst added is 0.1% to 1% of the total amount of the electroplating solution; During the electroplating process, the photocatalyst is activated by light, promoting the electroplating reaction and accelerating the reduction of metal ions; Step 6, curing and post-treatment of the electroplating layer: After the electroplating is completed, the electroplating layer is heat-treated and cured by heating the electroplating layer to 80°C to 150°C and maintaining it for 10 to 30 minutes to enhance the hardness and adhesion of the electroplating layer; Step 7, wastewater recovery and metal reuse: During the electroplating process, the electroplating wastewater is recovered and treated using electrochemical reduction and membrane separation technology. The metal ions in the wastewater are recovered and purified to ensure that the metal concentration in the wastewater is lower than the environmental emission standard, and the recovered metal ions are added back into the electroplating solution for recycling.

2. A high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The plasma treatment method is performed by low-temperature plasma or atmospheric plasma treatment, wherein the treatment temperature of the low-temperature plasma is 20° C. to 50° C., and the treatment time is 10 to 30 seconds.

3. The high-adhesion plastic electroplating green surface treatment method according to claim 2, characterized in that: The laser etching method uses a laser with a wavelength of 500 to 1000 nm to generate tiny pits on the plastic surface by focusing the laser beam. The laser power is 0.5W to 5W, and the laser scanning speed is 1mm / s to 10mm / s.

4. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The environmentally friendly metal ions of the electroplating solution are non-toxic compounds, including but not limited to copper chloride, zinc chloride or nickel chloride, and the total metal concentration of the electroplating solution ranges from 0.1 mol / L to 0.5 mol / L.

5. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The biomineralization material is a mineral salt of natural origin, wherein the mineralization component contained in the biomineralization material is selected from calcium, magnesium or phosphate, and the biomineralization material is dissolved in the electroplating solution to ensure that the concentration of the biomineralization material is in the range of 0.5% to 5% by weight.

6. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The current density in the low current density electrochemical plating process is 0.1 A / dm² to 0.3 A / dm², the plating temperature is 25°C to 40°C, and the plating time is 10 to 20 minutes.

7. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The nanoparticles are a mixture of nanosilver, nanographene and / or nanotitanium dioxide, and the particle size of the nanoparticles is 10 to 100 nm. The mass ratio of the nanoparticles is 0.5% to 3% of the total amount of the electroplating solution.

8. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The photocatalyst is a titanium-based photocatalytic material, the titanium-based photocatalyst contained therein is sodium titanate or titanium dioxide, and the added amount of the photocatalyst is 0.1% to 0.5% of the total amount of the electroplating solution.

9. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The heat treatment temperature in the electroplating layer curing and post-treatment steps is 90°C to 120°C, and the holding time is 15 to 25 minutes.

10. The high-adhesion plastic electroplating green surface treatment method according to claim 1, characterized in that: The wastewater treatment methods in the wastewater recovery and metal reuse steps include electrochemical reduction and membrane separation technology. The electrochemical reduction method is used to reduce metal ions in the wastewater, and the membrane separation technology is used to extract and recover the metal ions from the wastewater.

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