Method for surface metallization of special engineering plastics

Abstract

The application discloses a special engineering plastic surface metallization method. The method comprises five steps of ultrasonic oil removal, roughening pretreatment, sensitization, activation and chemical plating, and forms a metallization method with good bonding force between the special engineering plastic and the metal layer through reagent composition and parameter control in each step. The copper plating layer prepared on the surface of the special engineering plastic is dense, bright red and smooth, and has good bonding force with copper, and the special engineering plastic metallization component has long service life and can be widely applied to various industries such as aerospace, petrochemical industry, electronic appliances, automobile and machinery, and has good market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of surface metallization treatment technology for non-metallic materials, and specifically relates to a method for surface metallization of special engineering plastics. Background Technology

[0002] With the development of modern industry, the requirements of the electronics industry for key components (housing, support frame, etc.) are gradually moving towards lightweighting, so plastic has become the best choice to replace traditional metal materials.

[0003] Glass fiber reinforced polyphenylene sulfide (PPS) composite special engineering plastics are widely used plastic materials due to their light weight, high mechanical strength, and high temperature resistance. However, single-performance plastic materials can no longer meet the needs of technological development. To save production costs and improve the overall performance of products, surface modification technology is used to metallize the surface of plastics, forming composite multifunctional materials with plastic as the matrix and a metal coating on the surface. After surface metallization, plastics exhibit excellent electrical, magnetic, and thermal conductivity, and can also improve mechanical and corrosion resistance to a certain extent. Therefore, they are widely used in aerospace, petrochemical, electronics, automotive machinery, and daily necessities manufacturing industries. Currently, there are many methods for surface metallization of plastics, such as traditional vacuum thermal evaporation deposition, vacuum evaporation, ion plating, sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), electrophoretic deposition (EPD), and electroless plating.

[0004] Among methods for metallizing plastic surfaces, electroless plating technology is widely used due to its advantages such as wide applicability, simple equipment, strong uniform plating ability, controllable deposition thickness, ability to change the coating color as needed, and low pollution. The electroless plating process is actually a chemical oxidation-reduction reaction, a chemical deposition process with electron transfer and no external power source. It utilizes a reducing agent to chemically reduce metal ions in solution onto the surface of a catalytically active object, forming a metal coating; it is also known as electroless plating or autocatalytic plating. Its biggest difference from electroplating is that two processes occur on the same surface: oxidation by the reducing agent and reduction of metal ions. Plastic surfaces need pretreatment to give them a certain level of activity before metallization can be possible. Due to the low surface roughness, low free energy, hydrophobic surface, and lack of active functional groups for adsorbing metal particles, polyphenylene sulfide (PPS) substrates are difficult to metallize, and the bonding strength between the prepared metal layer and the PPS substrate is weak. Generally, appropriate pretreatment of the PPS substrate is performed before electroless plating to obtain PPS-based metallized materials with different properties. The surface pretreatment method and the composition of the chemical plating solution for polyphenylene sulfide (PPS)-based plastics play a crucial role in their surface metallization process. Existing technology, ZL2020107665637, discloses a surface roughening and metallization method for PPS-based substrates. However, this method uses chromic acid to roughen the substrate, but hexavalent chromium solution has significant corrosive and carcinogenic properties, posing a considerable impact on the environment and human health, which severely limits its application. Summary of the Invention

[0005] The purpose of this invention is to provide a simple, efficient, environmentally friendly method for metallizing the surface of special engineering plastics, which results in high surface roughness, good hydrophilicity, and strong adhesion between the chemically plated copper layer and the substrate.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A method for metallizing the surface of special engineering plastics, comprising the following steps: (1) Ultrasonic degreasing: The special engineering plastic substrate is placed in an ultrasonic cleaner for degreasing treatment for 10~20 min; the special engineering plastic is glass fiber reinforced polyphenyl sulfide; the degreasing agent used contains the following components: sodium phosphate 20 g / L, sodium hydroxide 10 g / L, sodium carbonate 30 g / L, emulsifier 2 ml / L, and water; the ultrasonic degreasing treatment temperature is 50~60℃; (2) Pretreatment before roughening: The degreased special engineering plastic substrate is placed in roughening solution A for 10-30 min, then transferred to roughening solution B for 5-15 min, and finally transferred to roughening solution C for 30-40 min. (3) Sensitization: The special engineering plastic substrate treated in step (2) is placed in the sensitization solution for 3-5 minutes; the sensitization solution contains the following components: 10 g / L stannous chloride, 40 mL / L hydrochloric acid, and water; (4) Activation: The sensitized special engineering plastic substrate is placed in an activation solution for 5-10 min; the activation solution contains the following components: palladium chloride 0.3-0.6 g / L, hydrochloric acid 2-5 ml / L, and water; (5) Chemical plating: The activated special engineering plastic substrate is placed in a copper plating solution for chemical plating.

[0007] Preferably, in step (2), the roughening solution A contains the following components: sulfuric acid 10-16 mL / L, glacial acetic acid 10-16 mL / L, citric acid 5-15 mL / L, formic acid 5-15 mL / L, and the balance being water; the roughening solution B contains sulfuric acid 20-40 mL / L, sodium sulfate 0.5-2 g / L, calcium sulfate 1.2-2 g / L, and water; the roughening solution C contains modified lignin 1-2 g / L, cellulose nanocrystals 0.5 g / L, sodium dodecylbenzenesulfonate 0.3 g / L, polyvinylpyrrolidone 1 g / L, and sulfuric acid 30 mL / L.

[0008] Preferably, the modified lignin is prepared by the following method: a. 100 mL of lignin aqueous solution, 5 g of sodium hydroxide, and 30 mL of hydrogen peroxide are mixed and reacted in a water bath at 65 °C for 2 h. After the reaction is completed, the mixture is dialyzed at room temperature for 10 h, with deionized water replaced every 5 h. After dialyzing, the resulting solution is dried in an oven at 95 °C for 12 h to obtain a solid powder; b. 5 g of the solid powder obtained in step a is dissolved in 100 mL of deionized water, then polyethyleneamine is added to adjust the pH of the solution to 10-12, and then 3 g of formaldehyde is added dropwise. The mixture is heated and stirred for 6 h. The mixture is poured into excess isobutanol and allowed to stand for 10-15 minutes. The precipitate is then separated by centrifugation and dried in an oven at 90 °C for 12 h to obtain the modified lignin.

[0009] Preferably, the concentration of the lignin aqueous solution in step a is 0.1 g / mL; and the mass ratio of the solid powder to polyethyleneamine in step b is 1 g: 0.05 g.

[0010] Preferably, the copper plating solution comprises the following components by mass percentage: 1-3% copper sulfate, 5-8% disodium EDTA, 15-25% sodium potassium tartrate, 15-20% triethanolamine, 0.5-0.8% formaldehyde, 3-5% sodium hydroxide, 0.3-0.5% potassium ferrocyanide, 0.1-0.2% aminopyridine, 0.1-0.2% sodium 3-mercapto-1-propanesulfonate, 0.5-0.8% polyethylene glycol, 0.3%-0.5% regulator, and the balance being pure water.

[0011] Preferably, the regulator is composed of 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 2:1.

[0012] Preferably, in step (2), the treatment temperature of roughening solution A is 30-40℃; the treatment temperature of roughening solution B is 50-60℃; and the treatment temperature of roughening solution C is 45℃.

[0013] Preferably, the sensitization temperature is 40~45℃.

[0014] Preferably, the activation temperature is 30~35℃.

[0015] Preferably, the electroless plating temperature is 45~50℃, the pH is 12.5, and the time is 5-8min.

[0016] All raw materials used in this invention were purchased commercially.

[0017] The adhesion strength between the surface of polyphenylene sulfide (PPS)-based specialty engineering plastics and the coating depends on two factors: surface roughness, which is the primary factor affecting the adhesion between the coating and the substrate; and the dipole interaction between the PPS-based specialty engineering plastic surface and the deposited metal layer. These two aspects must be well-matched to maximize the adhesion between the polymer and the deposited metal layer. Different surface roughening methods can produce different surface roughnesses for the PPS-based specialty engineering plastics, while different chemical plating solution compositions can form different metal layer structures with the substrate surface. Therefore, both surface roughening methods and chemical plating solution compositions play a crucial role in the metallization process of PPS-based specialty engineering plastics.

[0018] The stability of an electroless copper plating solution and the copper deposition rate are two contradictory aspects. Generally speaking, increasing the copper deposition rate decreases the stability of the plating solution, resulting in a porous, rough, and dull-colored coating. Conversely, decreasing the copper deposition rate increases the stability of the plating solution, resulting in a dense and bright coating. The goal is to obtain an electroless copper plating solution with a certain plating rate, high stability, and good coating quality. The deposition rate and stability of the plating solution are crucial for the practical application of electroless copper plating technology in production.

[0019] In this invention, aminopyridine and potassium ferrocyanide are used as stabilizers and promoters in the copper plating solution. On the one hand, they promote the electroless copper plating reaction; on the other hand, they bind the cuprous ions generated during the disproportionation reaction in the electroless copper plating process, ensuring the quality of the electroless copper layer and making the deposition reaction of electroless copper more stable. The lone pair electrons on the N atom of aminopyridine can act as electron donors, and the delocalized large π bond is an electron acceptor, thus favoring copper deposition to a certain extent. As the concentration of aminopyridine continues to increase, its competitive adsorption on the electrode surface becomes dominant, hindering the adsorption of other substances and reducing the deposition rate. Furthermore, aminopyridine reacts with Cu... + The complexation effect will reduce Cu 2+ The rate of transfer of the second electron during the reduction process stabilizes the plating solution. The modifier in this invention contains a specific ratio of 3-hydroxyquinoline and sodium lauryl sulfate; their synergistic effect effectively controls the deposition rate of metallic copper to prevent it from becoming too slow, while also improving the quality of the surface deposit.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1) The roughening pretreatment method of this invention employs three different roughening solutions for continuous treatment. Roughening solutions A and B create micro-roughened structures of varying degrees on the surface of the glass fiber reinforced polyphenylene sulfide substrate to enhance its adhesion to metallic copper. Roughening solution C, a compounded solution, allows modified lignin containing various hydrophilic functional groups such as phenolic hydroxyl, alcoholic hydroxyl, amino, and carboxyl groups to be adsorbed onto the substrate surface through physical action. Furthermore, the modified lignin exhibits strong adhesion to metallic copper. 2+ It has good adsorption properties, preventing excessive Cu. 2+ The formation of a large amount of Cu(OH)₂ precipitate results in a loose, rough, and dark-colored coating surface, while also making it difficult to control the copper deposition rate. Simultaneously, cellulose nanocrystals are adsorbed onto the substrate surface, and the synergistic effect of these two processes improves the surface energy and wettability of the glass fiber reinforced polyphenylene sulfide (PVPS) substrate. The combined use of the three roughening solutions allows for good adhesion between the PVPS substrate surface and the metal layer, extending the service life of the metallized PVPS material. The copper layer formed by the method described in this invention exhibits good adhesion to the PVPS; no peeling is observed in a 100-cross cross-section test with a 1mm spacing, and no peeling of the adhesive is observed after the cross-section test.

[0021] 2) The chemical copper plating solution of the present invention contains a specific ratio of regulator, which, in conjunction with other components, can effectively prevent Cu from being deposited. + The disproportionation reaction that occurs forms tiny copper particles that regulate the deposition rate of metallic copper, preventing the deposition rate from being too slow or too fast, which would affect the performance of the copper plating layer. When the two components are mixed in a specific ratio, they can work together to form a dense and bright metallic copper layer, improving the surface quality of the deposited layer. Attached Figure Description

[0022] Figure 1 The figure shows the test results of the plating solution stability and deposition rate of this invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to specific embodiments, but is not limited thereto. In the embodiments of the present invention, the workpiece used is a 25 mm × 40 mm glass fiber reinforced polyphenyl sulfide substrate.

[0024] Example 1 A method for metallizing the surface of special engineering plastics, comprising the following steps: (1) Ultrasonic degreasing: The special engineering plastic substrate is placed in an ultrasonic cleaner for degreasing treatment for 10~20 min; the special engineering plastic is glass fiber reinforced polyphenyl sulfide; the degreasing agent used contains the following components: sodium phosphate 20 g / L, sodium hydroxide 10 g / L, sodium carbonate 30 g / L, emulsifier OP-10 2 ml / L, and water; the ultrasonic degreasing treatment temperature is 50~60℃; (2) Pretreatment before roughening: The degreased special engineering plastic substrate is placed in roughening solution A and treated at 30-40℃ for 10-30 min, then transferred to roughening solution B and treated at 50-60℃ for 5-15 min, and finally transferred to roughening solution C and treated at 55℃ for 30-40 min. (3) Sensitization: The special engineering plastic substrate treated in step (2) is placed in the sensitization solution and treated at 40~45℃ for 3~5 min; the sensitization solution contains the following components: 10 g / L stannous chloride, 40 mL / L hydrochloric acid, and water; (4) Activation: The sensitized special engineering plastic substrate is placed in the activation solution and activated at 30~35℃ for 5~10min; the activation solution contains the following components: palladium chloride 0.3g / L, hydrochloric acid 2ml / L, and water; (5) Chemical plating: The activated special engineering plastic substrate is placed in the copper plating solution, the temperature is adjusted to 45℃, the pH is 12.5, and the chemical plating time is 5-8 minutes to obtain a workpiece with a uniform coating.

[0025] In step (2), the roughening solution A contains the following components: 10 mL / L sulfuric acid, 10 mL / L glacial acetic acid, 5 mL / L citric acid, 5 mL / L formic acid, and the remainder is water; the roughening solution B contains 20 mL / L sulfuric acid, 0.5 g / L sodium sulfate, 1.2 g / L calcium sulfate, and water; the roughening solution C contains 1 g / L modified lignin, 0.5 g / L cellulose nanocrystals, 0.3 g / L sodium dodecylbenzenesulfonate, 1 g / L polyvinylpyrrolidone, and 30 mL / L sulfuric acid. The modified lignin was prepared by the following method: a. 100 mL of lignin aqueous solution, 5 g of sodium hydroxide, and 30 mL of hydrogen peroxide were mixed and reacted in a water bath at 65 °C for 2 h. After the reaction was completed, the mixture was dialyzed at room temperature for 10 h, with the deionized water replaced every 5 h. After the dialyzed solution was completed, it was placed in an oven and dried at 95 °C for 12 h to obtain a solid powder; b. 5 g of the solid powder obtained in step a was dissolved in 100 mL of deionized water, and then 0.25 g of polyethyleneamine was added. The pH of the solution was adjusted to 10-12 using sodium hydroxide and / or hydrochloric acid. Then, 3 g of formaldehyde was added dropwise, and the mixture was heated and stirred for 6 h. The mixture was poured into excess isobutanol and allowed to stand for 10-15 minutes. The precipitate was separated by centrifugation and placed in an oven and dried at 90 °C for 12 h to obtain the modified lignin.

[0026] The copper plating solution has the following composition by mass percentage: 1% copper sulfate, 5% disodium EDTA, 15% sodium potassium tartrate, 15% triethanolamine, 0.5% formaldehyde, 3% sodium hydroxide, 0.3% potassium ferrocyanide, 0.1% aminopyridine, 0.1% sodium 3-mercapto-1-propanesulfonate, 0.5% polyethylene glycol, 0.3% regulator, and the balance being pure water; the regulator is composed of 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 2:1.

[0027] Example 2 A method for metallizing the surface of special engineering plastics, comprising the following steps: (1) Ultrasonic degreasing: The special engineering plastic substrate is placed in an ultrasonic cleaner for degreasing treatment for 10~20 min; the special engineering plastic is glass fiber reinforced polyphenyl sulfide; the degreasing agent used contains the following components: sodium phosphate 20 g / L, sodium hydroxide 10 g / L, sodium carbonate 30 g / L, emulsifier OP-10 2 ml / L, and water; the ultrasonic degreasing treatment temperature is 50~60℃; (2) Pretreatment before roughening: The degreased special engineering plastic substrate is placed in roughening solution A and treated at 30-40℃ for 10-30 min, then transferred to roughening solution B and treated at 50-60℃ for 5-15 min, and finally transferred to roughening solution C and treated at 55℃ for 30-40 min. (3) Sensitization: The special engineering plastic substrate treated in step (2) is placed in the sensitization solution and treated at 40~45℃ for 3~5 min; the sensitization solution contains the following components: 10 g / L stannous chloride, 40 mL / L hydrochloric acid, and water; (4) Activation: The sensitized special engineering plastic substrate is placed in the activation solution and activated at 30~35℃ for 5~10min; the activation solution contains the following components: palladium chloride 0.5g / L, hydrochloric acid 4ml / L, and water; (5) Chemical plating: The activated special engineering plastic substrate is placed in the copper plating solution, the temperature is adjusted to 47℃, the pH is 12.5, and the chemical plating time is 5-8 minutes to obtain a workpiece with a uniform coating.

[0028] In step (2), the roughening solution A contains the following components: 14 mL / L sulfuric acid, 13 mL / L glacial acetic acid, 10 mL / L citric acid, 10 mL / L formic acid, and the remainder is water; the roughening solution B contains 30 mL / L sulfuric acid, 1 g / L sodium sulfate, 1.5 g / L calcium sulfate, and water; the roughening solution C contains 1.5 g / L modified lignin, 0.5 g / L cellulose nanocrystals, 0.3 g / L sodium dodecylbenzenesulfonate, 1 g / L polyvinylpyrrolidone, and 30 mL / L sulfuric acid.

[0029] The modified lignin was prepared by the following method: a. 100 mL of lignin aqueous solution, 5 g of sodium hydroxide, and 30 mL of hydrogen peroxide were mixed and reacted in a water bath at 65 °C for 2 h. After the reaction was completed, the mixture was dialyzed at room temperature for 10 h, with the deionized water replaced every 5 h. After the dialyzed solution was completed, it was placed in an oven and dried at 95 °C for 12 h to obtain a solid powder; b. 5 g of the solid powder obtained in step a was dissolved in 100 mL of deionized water, and then 0.25 g of polyethyleneamine was added. The pH of the solution was adjusted to 10-12 using sodium hydroxide and / or hydrochloric acid. Then, 3 g of formaldehyde was added dropwise, and the mixture was heated and stirred for 6 h. The mixture was poured into excess isobutanol and allowed to stand for 10-15 minutes. The precipitate was separated by centrifugation and placed in an oven and dried at 90 °C for 12 h to obtain the modified lignin.

[0030] The copper plating solution has the following composition by mass percentage: 2% copper sulfate, 6% disodium EDTA, 20% sodium potassium tartrate, 18% triethanolamine, 0.7% formaldehyde, 4% sodium hydroxide, 0.4% potassium ferrocyanide, 0.15% aminopyridine, 0.15% sodium 3-mercapto-1-propanesulfonate, 0.7% polyethylene glycol, 0.4% regulator, and the balance being pure water; the regulator is composed of 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 2:1.

[0031] Example 3 A method for metallizing the surface of special engineering plastics, comprising the following steps: (1) Ultrasonic degreasing: The special engineering plastic substrate is placed in an ultrasonic cleaner for degreasing treatment for 10~20 min; the special engineering plastic is glass fiber reinforced polyphenyl sulfide; the degreasing agent used contains the following components: sodium phosphate 20 g / L, sodium hydroxide 10 g / L, sodium carbonate 30 g / L, emulsifier OP-10 2 ml / L, and water; the ultrasonic degreasing treatment temperature is 50~60℃; (2) Pretreatment before roughening: The degreased special engineering plastic substrate is placed in roughening solution A and treated at 30-40℃ for 10-30 min, then transferred to roughening solution B and treated at 50-60℃ for 5-15 min, and finally transferred to roughening solution C and treated at 55℃ for 30-40 min. (3) Sensitization: The special engineering plastic substrate treated in step (2) is placed in the sensitization solution and treated at 40~45℃ for 3~5 min; the sensitization solution contains the following components: 10 g / L stannous chloride, 40 mL / L hydrochloric acid, and water; (4) Activation: The sensitized special engineering plastic substrate is placed in the activation solution and activated at 30~35℃ for 5~10min; the activation solution contains the following components: palladium chloride 0.6g / L, hydrochloric acid 5ml / L, and water; (5) Chemical plating: The activated special engineering plastic substrate is placed in the copper plating solution, the temperature is adjusted to 50℃, the pH is 12.5, and the chemical plating time is 5-8 minutes to obtain a workpiece with a uniform coating.

[0032] In step (2), the roughening solution A contains the following components: 16 mL / L sulfuric acid, 16 mL / L glacial acetic acid, 15 mL / L citric acid, 15 mL / L formic acid, and the remainder is water; the roughening solution B contains 40 mL / L sulfuric acid, 2 g / L sodium sulfate, 2 g / L calcium sulfate, and water; the roughening solution C contains 2 g / L modified lignin, 0.5 g / L cellulose nanocrystals, 0.3 g / L sodium dodecylbenzenesulfonate, 1 g / L polyvinylpyrrolidone, and 30 mL / L sulfuric acid.

[0033] The modified lignin was prepared by the following method: a. 100 mL of lignin aqueous solution, 5 g of sodium hydroxide, and 30 mL of hydrogen peroxide were mixed and reacted in a water bath at 65 °C for 2 h. After the reaction was completed, the mixture was dialyzed at room temperature for 10 h, with the deionized water replaced every 5 h. After the dialyzed solution was completed, it was placed in an oven and dried at 95 °C for 12 h to obtain a solid powder; b. 5 g of the solid powder obtained in step a was dissolved in 100 mL of deionized water, and then 0.25 g of polyethyleneamine was added. The pH of the solution was adjusted to 10-12 using sodium hydroxide and / or hydrochloric acid. Then, 3 g of formaldehyde was added dropwise, and the mixture was heated and stirred for 6 h. The mixture was poured into excess isobutanol and allowed to stand for 10-15 minutes. The precipitate was separated by centrifugation and placed in an oven and dried at 90 °C for 12 h to obtain the modified lignin.

[0034] The copper plating solution has the following composition by mass percentage: 3% copper sulfate, 8% disodium EDTA, 25% sodium potassium tartrate, 20% triethanolamine, 0.8% formaldehyde, 5% sodium hydroxide, 0.5% potassium ferrocyanide, 0.2% aminopyridine, 0.2% sodium 3-mercapto-1-propanesulfonate, 0.8% polyethylene glycol, 0.5% regulator, and the balance being pure water.

[0035] The regulator is composed of 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 2:1.

[0036] Comparative Example 1 A method for metallizing the surface of special engineering plastics, the method and steps of which are basically the same as those in Example 3, the only difference being that the roughening liquid C is composed of 0.5 g / L cellulose nanocrystals, 0.3 g / L sodium dodecylbenzenesulfonate, 1 g / L polyvinylpyrrolidone, and 30 ml / L sulfuric acid.

[0037] Comparative Example 2 A method for metallizing the surface of special engineering plastics, the method and steps are basically the same as in Example 3, the only difference is that the roughening liquid C is composed of 2g / L modified lignin, 0.3g / L sodium dodecylbenzenesulfonate, 1g / L polyvinylpyrrolidone, and 30ml / L sulfuric acid.

[0038] Comparative Example 3 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the roughening solution C is composed of sodium dodecylbenzenesulfonate 0.3g / L, polyvinylpyrrolidone 1g / L, and sulfuric acid 30ml / L.

[0039] Comparative Example 4 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution does not contain any modifier.

[0040] Comparative Example 5 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains only 3-hydroxyquinoline as the modifier.

[0041] Comparative Example 6 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains only sodium lauryl sulfate as the modifier.

[0042] Comparative Example 7 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 4:1.

[0043] Comparative Example 8 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 3:1.

[0044] Comparative Example 9 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains 3-hydroxyquinoline and sodium lauryl sulfate in a 1:1 mass ratio as the regulator.

[0045] Comparative Example 10 A method for metallizing the surface of special engineering plastics is basically the same as that in Example 3, except that the copper plating solution contains 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 1:2.

[0046] Performance testing The adhesion between the surface coating and the substrate was tested using the cross-cut adhesion test on the workpieces prepared in Examples 1-3 and Comparative Examples 1-10. Visual inspection was performed to check for any missed or excessive coating on the surface of each workpiece. The ductility of the coating was tested using a TH-8201A tensile testing machine, and the tensile strength of the coating was tested using a tension testing machine. The test results are shown in Table 1.

[0047] Table 1 Test Results To further illustrate the technical effects of the present invention, the relationship between the stability of the plating solution and the deposition rate in the methods of Examples 1-3 and Comparative Examples 1-10 was also investigated. The stability of the plating solution was tested using a catalytic ink acceleration test. The effective component of this ink is K ions, which, after activation treatment, exhibit good catalytic activity. 1 mL of ink was accurately measured and diluted to 1000 mL as the accelerating ink for this experiment. At 45°C, 10 mL of accelerating ink was added dropwise to 50 mL of plating solution, and the decomposition of the plating solution was observed. The time taken for a large amount of copper powder to be produced in the plating solution was recorded as the stabilization time of the plating solution. The deposition rate of the deposited plastic was determined using the weight gain method. The copper deposition rate was measured at 45°C and pH = 12.5, after 20 min of plating. The deposition rate v (μm / h) of the coating was calculated using the following formula: v = △W × 10 4 / ( ρSt) In the formula, △W represents the mass difference before and after plating, in grams; P represents the density of copper, 8.93 g / cm³. 3 S is the surface area, in cm² 2 T represents the plating time, in hours. Specific test results are as follows: Figure 1 As shown in the data. Figure 1It can be seen that the plating solutions in Examples 1-3 of this invention have good stability, with an average deposition rate of 7.70 μm / h and an average stabilization time of 31.97 min. Compared with Examples 1-3, Comparative Examples 1-3 show no significant changes in either plating solution stability or deposition rate. However, Comparative Examples 4-6 exhibit poor plating solution stability and a faster deposition rate, easily forming uneven copper particles and resulting in a loose and rough coating surface. Data from Comparative Examples 7-10 show that as the amount of 3-hydroxyquinoline in the regulator decreases, the stabilization time of the plating solution initially increases and then decreases, while the deposition rate initially slows and then accelerates. This is because the stability of the electroless copper plating solution and the copper deposition rate are inherently contradictory. A faster copper deposition rate leads to decreased plating solution stability, resulting in a loose, rough, and dark-colored coating surface; conversely, a slower copper deposition rate increases plating solution stability, resulting in a dense and bright coating. The regulator in this invention works synergistically to adjust the copper plating rate, so that the plating solution remains stable even when the copper plating rate is relatively high. The resulting copper plating layer is bright and dense, and the plating layer has good adhesion to the glass fiber reinforced polyphenyl sulfide substrate. This is a good method for metallizing the surface of special engineering plastics and is suitable for industrial production and promotion.

[0048] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for metallizing the surface of special engineering plastics, characterized in that, It includes the following steps: (1) Ultrasonic degreasing: The special engineering plastic substrate is placed in an ultrasonic cleaner for degreasing treatment for 10~20 min; the special engineering plastic is glass fiber reinforced polyphenyl sulfide; the degreasing agent used contains the following components: sodium phosphate 20 g / L, sodium hydroxide 10 g / L, sodium carbonate 30 g / L, emulsifier 2 ml / L, and water; the ultrasonic degreasing treatment temperature is 50~60℃; (2) Pretreatment before roughening: The degreased special engineering plastic substrate is placed in roughening solution A for 10-30 min, then transferred to roughening solution B for 5-15 min, and finally transferred to roughening solution C for 30-40 min. (3) Sensitization: The special engineering plastic substrate treated in step (2) is placed in the sensitization solution for 3-5 minutes; the sensitization solution contains the following components: 10 g / L stannous chloride, 40 mL / L hydrochloric acid, and water; (4) Activation: The sensitized special engineering plastic substrate is placed in an activation solution for 5-10 min; the activation solution contains the following components: palladium chloride 0.3-0.6 g / L, hydrochloric acid 2-5 ml / L, and water; (5) Chemical plating: The activated special engineering plastic substrate is placed in a copper plating solution for chemical plating.

2. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, In step (2), the roughening solution A contains the following components: sulfuric acid 10-16 mL / L, glacial acetic acid 10-16 mL / L, citric acid 5-15 mL / L, formic acid 5-15 mL / L, and the balance is water; the roughening solution B contains sulfuric acid 20-40 mL / L, sodium sulfate 0.5-2 g / L, calcium sulfate 1.2-2 g / L, and water; the roughening solution C contains modified lignin 1-2 g / L, cellulose nanocrystals 0.5 g / L, sodium dodecylbenzenesulfonate 0.3 g / L, polyvinylpyrrolidone 1 g / L, and sulfuric acid 30 mL / L.

3. The method for metallizing the surface of special engineering plastics according to claim 2, characterized in that, The modified lignin was prepared by the following method: a. 100 mL of lignin aqueous solution, 5 g of sodium hydroxide, and 30 mL of hydrogen peroxide were mixed and reacted in a water bath at 65 °C for 2 h. After the reaction was completed, the mixture was dialyzed at room temperature for 10 h, with the deionized water replaced every 5 h. After the dialyzed solution was completed, it was placed in an oven and dried at 95 °C for 12 h to obtain a solid powder; b. 5 g of the solid powder obtained in step a was dissolved in 100 mL of deionized water, and then polyethyleneamine was added to adjust the pH of the solution to 10-12. Then 3 g of formaldehyde was added dropwise, and the mixture was heated and stirred for 6 h. The mixture was poured into excess isobutanol and allowed to stand for 10-15 minutes. The precipitate was separated by centrifugation and placed in an oven and dried at 90 °C for 12 h to obtain the modified lignin.

4. The method for metallizing the surface of special engineering plastics according to claim 3, characterized in that, In step a, the concentration of the lignin aqueous solution is 0.1 g / mL; in step b, the mass ratio of the solid powder to polyethyleneamine is 1:0.

05.

5. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, The copper plating solution has the following composition by mass percentage: copper sulfate 1-3%, disodium EDTA 5-8%, potassium sodium tartrate 15-25%, triethanolamine 15-20%, formaldehyde 0.5-0.8%, sodium hydroxide 3-5%, potassium ferrocyanide 0.3-0.5%, aminopyridine 0.1-0.2%, sodium 3-mercapto-1-propanesulfonate 0.1-0.2%, polyethylene glycol 0.5-0.8%, regulator 0.3-0.5%, and the balance being pure water.

6. The method for metallizing the surface of special engineering plastics according to claim 5, characterized in that, The regulator is composed of 3-hydroxyquinoline and sodium lauryl sulfate in a mass ratio of 2:

1.

7. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, In step (2), the treatment temperature of roughening solution A is 30-40℃; the treatment temperature of roughening solution B is 50-60℃; and the treatment temperature of roughening solution C is 65℃.

8. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, The sensitization temperature is 40~45℃.

9. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, The activation temperature is 30~35℃.

10. The method for metallizing the surface of special engineering plastics according to claim 1, characterized in that, The electroless plating temperature is 45~50℃, the pH is 12.5, and the time is 5-8 minutes.

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