A metal plating process and its application

Abstract

The present application relates to C25D5, more particularly, the present application relates to a metal plating process and its application. The steps are as follows: (1) resin pretreatment; (2) coating preparation; (3) pre-impregnation treatment; (4) reduction; (5) electroplating. When the viscosity of epoxy resin is 800-1000MPa.s, the density of polyamide resin is 0.8-1.2g / cm3, not only the conductivity of the surface plating of the final electroplated product can be improved, but also the glossiness of the electroplated product is unexpectedly improved; in the present application, the roughening process does not use high oxidizing substances such as chromic anhydride, fluoride, sulfuric acid and other strong acids, and the activation process by adding noble metals such as titanium salt and tin salt is also used, which not only reduces the cost, but also is more environmentally friendly and reduces the pollution to the environment.

Description

Technical Field

[0001] This invention relates to C25D5, and more specifically, to a metal plating process and its application. Background Technology

[0002] Electroplating the surface of plastic products not only enhances their appearance but also improves the mechanical strength of the external structural layers, making them less prone to aging and thus extending their lifespan. Due to these advantages, the technology of using metal plating on plastic surfaces is becoming increasingly widespread.

[0003] Patent CN112048745A provides a process to improve the adhesion between the metallized coating on the surface of a plastic oscillator and the plastic substrate, and to improve the PIM value of the coating. This is achieved by combining chemical roughening with a strong acid containing fluoride and mechanical roughening, thus enhancing the adhesion between the plastic substrate and the surface metallized coating. Patent CN108588776A provides a nickel-free environmentally friendly electroplating process. By avoiding nickel-free treatment during electroplating, it eliminates the safety concerns associated with the presence of nickel ions, such as carcinogenicity and allergic reactions.

[0004] However, in existing technologies, roughening processes typically require the use of highly oxidizing substances such as strong acids like chromium anhydride, fluorides, and sulfuric acid, combined with activation processes using precious metals such as titanium salts and tin salts. This not only results in high costs but also causes significant environmental pollution. Summary of the Invention

[0005] To address the above problems, the first aspect of the present invention provides a metal plating process comprising the following steps: (1) resin pretreatment; (2) coating preparation; (3) pre-immersion treatment; (4) reduction; and (5) electroplating.

[0006] As a preferred technical solution of the present invention, step (1) specifically involves immersing the resin in an alkaline solution at 40-44°C for 2-4 minutes.

[0007] Preferably, step (1) specifically involves soaking 2-5g of resin in 40-70mL of alkaline solution at 40-44℃ for 2-4 minutes, then removing it and rinsing it with 250mL of distilled water to obtain substance A.

[0008] More preferably, the resin is ABS resin.

[0009] ABS (Acrylonitrile Butadiene Styrene) resin is a thermoplastic resin composed of acrylonitrile, butadiene, and styrene.

[0010] As a preferred embodiment of the present invention, the alkaline solution comprises an alkaline substance and an emulsifier.

[0011] Preferably, the alkaline solution comprises 95-132 parts by weight of alkaline substance and 2-3.5 parts by weight of emulsifier.

[0012] As a preferred embodiment of the present invention, the alkaline substance is selected from one or more of sodium hydroxide aqueous solution, sodium phosphate aqueous solution, and sodium bicarbonate aqueous solution.

[0013] Preferably, the sodium hydroxide aqueous solution is a 40 wt% sodium hydroxide aqueous solution; the sodium phosphate aqueous solution is a 40 wt% sodium phosphate aqueous solution; and the sodium bicarbonate aqueous solution is a 35 wt% sodium bicarbonate aqueous solution.

[0014] More preferably, the weight ratio of sodium hydroxide aqueous solution, sodium phosphate aqueous solution, and sodium bicarbonate aqueous solution is (40-60):(35-42):(20-30).

[0015] As a preferred technical solution of the present invention, the raw materials for the coating in step (2) include epoxy resin, polyamide resin, aluminum powder and solvent.

[0016] Preferably, the weight ratio of epoxy resin, polyamide resin, aluminum powder and solvent is (0.5-0.85):(0.6-0.95):(2.5-4.3):(3-8).

[0017] Preferably, the aluminum powder has a diameter of 17-29 μm and an iron content of <0.3 wt%.

[0018] Preferably, the solvent is xylene.

[0019] As a preferred embodiment of the present invention, the epoxy resin has a viscosity of 800-1000 MPa·s at 25°C.

[0020] In a preferred embodiment of the present invention, the polyamide resin has a density of 0.8-1.2 g / cm³. 3 .

[0021] Preferably, step (2) specifically involves mixing the raw materials for the coating according to a weight ratio, stirring, and obtaining the coating. 1.3-2.8g of the coating is applied to the surface of substance A using a coating applicator and cured at 25°C for 7-10 hours to obtain substance B.

[0022] Through extensive experiments, the applicant discovered that adding epoxy resin of a specific viscosity and polyamide resin of a specific density during coating preparation—specifically, the epoxy resin viscosity being 800-1000 MPa·s and the polyamide resin density being 0.8-1.2 g / cm³—is effective. 3This process not only improves the conductivity of the final electroplated product's surface coating but also unexpectedly enhances its gloss. The applicant speculates that this may be due to the combined effect of epoxy resin of a specific viscosity and polyamide resin of a specific density, which improves the fluidity of the coating material, thereby affecting the dispersion of the various substances in the coating and significantly increasing the bonding force between molecules. This change in bonding force also facilitates the loading of graphene oxide onto the resin during the pre-immersion treatment in step (3), ultimately resulting in a denser coating structure in the electroplated product obtained in step (5), thereby reducing the resistance value and improving its conductivity. Furthermore, it increases the stability of the coating, allowing it to maintain a good gloss for a longer period of time.

[0023] As a preferred embodiment of the present invention, the prepreg solution includes unbranched alcohols, branched alcohols, and ketones.

[0024] Preferably, the weight ratio of unbranched alcohol, branched alcohol, and ketone is (1-4):(2-3):1. More preferably, the unbranched alcohol is ethanol; the branched alcohol is isopropanol; and the ketone is cyclohexanone.

[0025] As a preferred embodiment of the present invention, the prepreg is obtained by modification with graphene oxide.

[0026] Preferably, step (3) specifically involves preparing a 50-100 mL solution 1 from unbranched alcohols, branched alcohols, and ketones in a weight ratio. Solution 1 is then diluted with 2-3.4 times its weight of distilled water to obtain solution 2. Graphene oxide powder is then added to solution 2 to achieve a concentration of 3.6-4.4 mg / mL, thus obtaining a pre-impregnation solution. Substance B is then immersed in the pre-impregnation solution for 5-20 minutes to obtain substance C.

[0027] Preferably, step (4) involves immersing substance C in 20-100 mL of a 40-45 mg / mL ascorbic acid solution, reacting for 0.6-0.8 h in a water bath at 80 °C, removing the substance, and vacuum drying it at 50 °C for 6-8 h to obtain substance D.

[0028] Preferably, step (5) specifically involves electroplating different metal coatings onto material D in an electroplating tank using an electroplating machine.

[0029] Further preferred, step (5) involves electroplating a copper layer onto material D in an electroplating tank using an electroplating machine: (1) Preparing the electroplating solution: The electroplating solution is prepared by adding 70wt% sodium hydroxide solution to the electroplating pre-preparation solution and adjusting the pH to 11.5. The electroplating pre-preparation solution includes a saturated copper sulfate aqueous solution, a saturated potassium sodium tartrate aqueous solution, and a 36-36.5wt% formaldehyde aqueous solution. The volume ratio of the saturated copper sulfate aqueous solution, the saturated potassium sodium tartrate aqueous solution, and the 36-36.5wt% formaldehyde aqueous solution is (11-13):(13.4-13.8):(10-20); (2) Electroplating: The electroplating solution is placed in the electroplating machine to electroplat material D at a temperature of 25-30℃ for 40-70 minutes to obtain the electroplated product.

[0030] The second aspect of the present invention provides an application of a metal plating process, which is applied in the fields of protective decoration and corrosion prevention.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] Adding specific alkaline substances and controlling their proportions, especially adding aqueous solutions of sodium hydroxide, sodium phosphate, and sodium bicarbonate, and maintaining a weight ratio of (40-60):(35-42):(20-30), facilitates more thorough surface degreasing of ABS resin during initial treatment, simplifies subsequent steps, and results in electroplated products with excellent low-temperature and high-temperature stability. When the viscosity of the epoxy resin is 800-1000 MPa·s and the density of the polyamide resin is 0.8-1.2 g / cm³, the desired effect is achieved. 3 This process not only improves the conductivity of the final electroplated product's surface coating but also unexpectedly enhances its gloss. During pre-immersion treatment, controlling the weight ratio of unbranched alcohols, branched alcohols, and ketones to (1-4):(2-3):1 allows for a good synergistic effect with the aluminum powder (17-29 μm in diameter) used in the coating. This facilitates trace electron transfer between copper and aluminum during electroplating, further improving the stability of the final electroplated product. In this invention, the roughening process avoids the use of highly oxidizing substances such as chromic anhydride, fluorides, and sulfuric acid, and also avoids activation processes involving the addition of precious metals like titanium and tin salts. This not only reduces costs but is also more environmentally friendly, minimizing pollution. Detailed Implementation

[0033] Example

[0034] The raw materials used in the preparation of the compositions in the examples were all commercially available. The emulsifier was purchased from Haian Petrochemical (TX-10), the epoxy resin was purchased from Phoenix (6101, viscosity at 25°C: 850-920 MPa·s), and the polyamide resin was purchased from Guoshibang (GSB, density: 1.01 g / cm³). 3 Aluminum powder was purchased from Shengtong, with a diameter of 19-21μm and an iron content of <0.1wt%. ABS resin was purchased from Chi Mei in Taiwan, grade PC-365. Graphene oxide powder was purchased from Yuanye, model S28018. Ascorbic acid was purchased from Shandong Hedun New Material Co., Ltd.

[0035] Example 1

[0036] This example provides a metal plating process with the following steps: (1) resin pretreatment; (2) coating preparation; (3) pre-immersion treatment; (4) reduction; (5) electroplating.

[0037] Step (1) specifically involves immersing 2.5g of resin in 50mL of alkaline solution at 42℃ for 2.5min, then removing it and rinsing it with 250mL of distilled water to obtain substance A. The resin is ABS resin.

[0038] The alkaline solution comprises 114 parts by weight of alkaline substance and 2.8 parts by weight of emulsifier.

[0039] Alkaline substances include aqueous solutions of sodium hydroxide, sodium phosphate, and sodium bicarbonate. The weight ratio of these solutions is 50:39:25.

[0040] The sodium hydroxide aqueous solution is a 40 wt% sodium hydroxide aqueous solution; the sodium phosphate aqueous solution is a 40 wt% sodium phosphate aqueous solution; the sodium bicarbonate aqueous solution is a 35 wt% sodium bicarbonate aqueous solution.

[0041] The raw materials for the coating in step (2) include epoxy resin, polyamide resin, aluminum powder and solvent.

[0042] The weight ratio of epoxy resin, polyamide resin, aluminum powder, and solvent is 0.7:0.8:3:4.5. The solvent is xylene.

[0043] Step (2) specifically involves mixing the raw materials for the coating according to the weight ratio, stirring, and obtaining the coating. 1.5g of the coating is applied to the surface of substance A through a coating applicator and cured at 25°C for 9 hours to obtain substance B.

[0044] The prepreg solution includes unbranched alcohols, branched alcohols, and ketones. The weight ratio of unbranched alcohols, branched alcohols, and ketones is 2:2.5:1. The unbranched alcohol is ethanol; the branched alcohol is isopropanol; and the ketone is cyclohexanone.

[0045] The prepreg solution was obtained by modifying it with graphene oxide.

[0046] Step (3) specifically involves preparing a 70 mL solution 1 from unbranched alcohols, branched alcohols, and ketones in a specific weight ratio. 2.5 times the volume of distilled water is added to solution 1 to obtain solution 2. Then, graphene oxide powder is added to solution 2 to achieve a concentration of 3.8 mg / mL, thus obtaining a pre-impregnation solution. Substance B is then immersed in the pre-impregnation solution for 12 minutes to obtain substance C.

[0047] Step (4) involves immersing substance C in 40 mL of a 42 mg / mL ascorbic acid solution, reacting it in a water bath at 80°C for 0.7 h, removing it, and vacuum drying it at 50°C for 7 h to obtain substance D.

[0048] Step (5) Electroplating copper coating on material D in an electroplating tank using an electroplating machine: (1) Preparing the electroplating solution: The electroplating solution is prepared by adding 70wt% sodium hydroxide solution to the electroplating pre-preparation solution and adjusting the pH to 11.5. The electroplating pre-preparation solution includes saturated copper sulfate aqueous solution, saturated potassium sodium tartrate aqueous solution and 36wt% formaldehyde aqueous solution. The volume ratio of saturated copper sulfate aqueous solution, saturated potassium sodium tartrate aqueous solution and 36wt% formaldehyde aqueous solution is 12:13.6:15; (2) Electroplating: The electroplating solution is placed in the electroplating machine to electroplat material D at a temperature of 25℃ for 55min to obtain the electroplated product.

[0049] Example 2

[0050] This example provides a metal coating process. Unlike Example 1, step (1) involves immersing 2.6g of resin in 60mL of alkaline solution at 40℃ for 4 minutes, then rinsing with 250mL of distilled water to obtain substance A. The resin is ABS resin. In step (2), the weight ratio of the coating raw materials—epoxy resin, polyamide resin, aluminum powder, and solvent—is 0.6:0.7:2.6:4. Step (3) involves preparing 50mL of solution 1 (unbranched alcohol, branched alcohol, and ketone organic compounds) by weight ratio. Solution 1 is then diluted with twice the amount of distilled water to obtain solution 2. Graphene oxide powder is then added to solution 2 to achieve a concentration of 3.6mg / mL, resulting in a pre-impregnation solution. Substance B is immersed in the pre-impregnation solution for 20 minutes to obtain substance C. Step (4) involves immersing substance C in 50 mL of a 44 mg / mL ascorbic acid solution, reacting it in a water bath at 80°C for 0.6 h, removing it, and vacuum drying it at 50°C for 6 h to obtain substance D.

[0051] Example 3

[0052] This example provides a metal coating process. Unlike Example 1, in step (2), the weight ratio of the coating raw materials—epoxy resin, polyamide resin, aluminum powder, and solvent—is 0.8:0.95:4:6. Specifically, step (3) involves preparing a 60 mL solution 1 from unbranched alcohols, branched alcohols, and ketones in a specific weight ratio. Three times the volume of distilled water is added to solution 1 to obtain solution 2. Then, graphene oxide powder is added to make the concentration of graphene oxide powder in solution 2 4 mg / mL, resulting in a pre-impregnation solution. Substance B is immersed in the pre-impregnation solution for 20 min to obtain substance C.

[0053] Example 4

[0054] This example provides a metal plating process, which differs from Example 1 in that the weight ratio of sodium hydroxide aqueous solution, sodium phosphate aqueous solution, and sodium bicarbonate aqueous solution is 20:40:25.

[0055] Example 5

[0056] This example provides a metal plating process, which differs from Example 1 in that the weight ratio of epoxy resin, polyamide resin, aluminum powder and solvent is 0.6:1.3:3:4.5.

[0057] Performance testing:

[0058] 1. Gloss Test: Fifty people were randomly selected and divided into five groups, numbered 1-5. Group 1 observed the electroplated product obtained in Example 1, Group 2 observed the electroplated product obtained in Example 2, and so on. The gloss of the electroplated products was scored out of 10 points, with higher scores indicating better gloss. The average score of each group was taken, and the results are shown in Table 1.

[0059] Table 1

[0060] Group score 1 9.5 2 9.0 3 9.3 4 8.1 5 7.8

[0061] 2. Resistance Value Test: The electroplated products obtained in Examples 1-5 were subjected to resistance value tests according to GB / T 6146-2010. Resistance values ​​R < 1Ω were classified as Grade 1, 1Ω ≤ R ≤ 1.5Ω as Grade 2, and 1.5Ω < R ≤ 2Ω as Grade 3. The results are shown in Table 2.

[0062] Table 2

[0063]

[0064]

[0065] 3. Low-temperature stability test: After the electroplated products obtained in Examples 1-5 were placed at -5℃ for 30 days, they were taken out and left to stand at 25℃ for 24 hours. The results are shown in Table 3.

[0066] Table 3

[0067] Example Appearance 1 No paint film peeling or separation 2 No paint film peeling or separation 3 No paint film peeling or separation 4 No paint film peeling or separation 5 Paint film peeling and separation

[0068] 4. High-temperature stability test: After the electroplated products obtained in Examples 1-5 were placed at 35°C for 30 days, they were taken out and left to stand at 25°C for 24 hours. The results are shown in Table 4.

[0069] Table 4

[0070] Example Appearance 1 No paint film peeling or separation 2 No paint film peeling or separation 3 No paint film peeling or separation 4 Paint film peeling and separation 5 No paint film peeling or separation

[0071] 5. Thermal cycling test: The electroplated products obtained in Examples 1-5 were subjected to 1000 cycles at -5 to 35°C, with each temperature range of 35°C and -5°C lasting for 15 minutes. The results are shown in Table 5.

[0072] Table 5

[0073] Example Appearance 1 No whiskers, smooth 2 No whiskers, smooth 3 No whiskers, smooth 4 No whiskers, with pits 5 It has whiskers and pits.

Claims

1. A metal plating process, characterized in that, The steps are as follows: (1) Resin pretreatment: Immerse ABS resin in an alkaline solution at 40-44℃ for 2-4 minutes. The alkaline solution is composed of sodium hydroxide aqueous solution, sodium phosphate aqueous solution, sodium bicarbonate aqueous solution in a weight ratio of (40-60):(35-42):(20-30) and emulsifier; (2) Coating preparation; (3) Prepreg treatment; (4) Reduction; (5) Electroplating; The raw materials for the coating in step (2) include epoxy resin, polyamide resin, aluminum powder, and solvent. The weight ratio of epoxy resin, polyamide resin, aluminum powder, and solvent is (0.5-0.85):(0.6-0.95):(2.5-4.3):(3-8). The aluminum powder has a diameter of 17-29 μm and an iron content of <0.3 wt%. The epoxy resin has a viscosity of 800-1000 MPa·s at 25°C, and the polyamide resin has a density of 0.8-1.2 g / cm³. 3 ; The prepreg solution was obtained by modifying it with graphene oxide; The sodium hydroxide aqueous solution is a 40 wt% sodium hydroxide aqueous solution; the sodium phosphate aqueous solution is a 40 wt% sodium phosphate aqueous solution; and the sodium bicarbonate aqueous solution is a 35 wt% sodium bicarbonate aqueous solution.

2. The metal plating process according to claim 1, characterized in that, The prepreg solution includes unbranched alcohols, branched alcohols, and ketones.

3. An application of the metal plating process according to claim 1 or 2, characterized in that, The metal plating process is applied in the fields of protective decoration and corrosion prevention.

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