Bright silver plating additive composition and application method thereof in cyanide-free silver plating

Abstract

The invention belongs to the technical field of silver electroplating, and particularly relates to a bright silver plating additive composition and a use method thereof in cyanide-free silver plating. Comprising a main compounding agent with the mass concentration of 20-54 g / L, an auxiliary compounding agent with the mass concentration of 0.01-3.5 g / L, a compounding additive with the mass concentration of 0.05-0.65 g / L, an ionic surfactant with the mass concentration of 0.5-10 g / L, a nonionic surfactant with the mass concentration of 1-25 g / L and the balance of water. According to the bright silver plating additive composition, all the selected components are low-toxicity or non-toxic compounds, industrial production is easy to achieve, a plating layer is more complete, the brightness is improved, plating layer crystallization is more perfect, the brightness and adhesiveness of the plating layer are higher, the impurity removal effect is obvious, plating layer crystallization is more uniform and compact, the wear resistance of the plating layer is improved, and the service life of the plating layer is prolonged. And the adhesive force of the silver coating and the surface of the base body is improved, and the uniformity and the brightness of the coating surface are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electroplating silver, and in particular relates to a bright silver plating additive composition and a method for using the same in cyanide-free silver plating. Background Art

[0002] Precious metals are widely used in the electronics industry, medical field, aerospace, environmental protection field and optical field due to their stable chemical properties, good thermal and electrical conductivity, soft texture, high ductility and excellent antibacterial properties. However, due to its high price, choosing relatively cheap precious metal silver as electroplating material can save costs without reducing product quality.

[0003] Silver electroplating is still one of the mainstream technologies in the field of electroplating. The silver electroplating processes used at home and abroad are mostly cyanide silver plating with high current efficiency, good dispersion ability, strong covering ability, fine crystallization and good solution stability. However, cyanide is extremely toxic, and trace intake may also cause poisoning or even death. During the electroplating process, the cyanide tank needs to be covered and locked, and the use of cyanide also requires wearing special protective gear, which causes great inconvenience and operational safety hazards. At the same time, the wastewater and waste liquid need to be specially collected and uniformly treated. They can only be discharged after qualified treatment, otherwise it will cause great harm to the environment.

[0004] With the development of the times, the awareness of environmental protection is constantly improving. Cyanide silver plating will gradually withdraw from the stage of the times, and cyanide-free silver plating will become a mainstream in the new era. Many cyanide-free silver plating solution formulas that do not contain cyanide have sprung up like mushrooms after rain: ① Chinese patent document 202211196663.6 discloses a cyanide-free silver plating solution and a process method thereof, and the plating solution is mainly prepared by silver nitrate, sulfosalicylic acid, ammonium acetate, ammonium carbonate and water. ② Chinese patent document 201310471133.2 discloses a cyanide-free silver plating method, succinimide 80-100g / L, sodium tetraborate 10-40g / L, polyethylene glycol 0.2g / L, benzotriazole 0.02g / L, SeO2 0.06g / L, silver nitrate 40-70g / L, ammonia water to adjust the pH to 9-10. ③ Chinese patent document 201310451471.X discloses a cyanide-free silver plating solution and an electroplating method thereof, wherein the cyanide-free silver plating solution comprises 25 to 35 g / L of silver nitrate, 90 to 110 g / L of 2,4-imidazolidinedione or 2,4-imidazolidinedione substituted with any group on a heterocyclic ring, 60 to 90 g / L of carbonate, 30 to 40 g / L of pyrophosphate, 0.30 to 0.45 g / L of hydroxypropyl propargyl ether, 0.10 to 0.25 g / L of sodium o-sulfonate benzaldehyde and 0.15 to 0.30 g / L of N,N-bis(hydroxyethyl)ethylamine.

[0005] There are some problems with the prior art: Chinese patent document 202211196663.6 discloses a cyanide-free silver plating solution and a process method thereof. Although the plating solution has good stability and a long service life, the current density range is relatively narrow (0.1-0.3A / dm2). [See Chinese patent document 202211196663.6, page 2 (0022)], ammonia in the solution is volatile, the pH value is prone to change, and it is easy to cause production environmental pollution. Chinese patent document 201310471133.2 discloses a cyanide-free silver plating method. Although the pH value of the plating solution allows a wide range and the coating has high gloss, the succinimide complexing agent is easily hydrolyzed, the stability of the plating solution is poor, and the cost is high. Chinese patent document 201310451471.X discloses a cyanide-free silver plating solution and its electroplating method, [see page 2 of the specification (0021) for details, the current density is 0.3-0.5A / dm2], the current density range is narrow, and the brightness of the coating is not high. The existing cyanide-free silver plating formula has obvious shortcomings: ① poor appearance and adhesion of the silver plating layer; ② poor stability of the plating solution and short service life; ③ high cost of the silver plating solution and other major problems. Summary of the invention

[0006] The invention aims to provide a bright silver plating additive composition and a method for using the same in cyanide-free silver plating, aiming to solve the technical problems in the prior art of poor appearance and adhesion of the silver plating layer, poor stability of the plating solution, short service life and high cost of the silver plating solution.

[0007] To achieve the above purpose, the bright silver plating additive composition provided by the embodiment of the present invention comprises a main compounding agent with a mass concentration of 20-54 g / L, an auxiliary compounding agent with a mass concentration of 0.01-3.5 g / L, a compounding additive with a mass concentration of 0.05-0.65 g / L, an ionic surfactant with a mass concentration of 0.5-10 g / L, a non-ionic surfactant with a mass concentration of 1-25 g / L, and the balance of water.

[0008] As an optional solution of the present invention, the main compounding agent is one or more of tea polyphenols, linoleic acid, and 1.6.7-trihydroxyxanthone.

[0009] As an optional solution of the present invention, the auxiliary compounding agent is one or more of N-(substituted thiazol-2-yl)-chrysanthemum amide, pterostilbene, and 4-bromoacetate.

[0010] As an optional solution of the present invention, the compounding additive is one or more of 4-thiazolidine-2-benzoyl urea, dithizone, and resveratrol.

[0011] As an optional solution of the present invention, the anionic surfactant is one or more of sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), and sodium hexadecyl sulfonate (AS).

[0012] As an optional solution of the present invention, the non-ionic surfactants are one or more of polyethylene glycol-400, polypropylene glycol-600, and Triton-100.

[0013] As an optional solution of the present invention, the water is one of deionized water, double distilled water and distilled water.

[0014] Based on the same inventive concept, the present application also provides a method for using the bright silver plating additive composition in cyanide-free silver plating, the method comprising the following steps:

[0015] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh the required mass concentration of 0.5-10 g / L of ionic surfactant and the mass concentration of 1-25 g / L of non-ionic surfactant in a container and stir until completely dissolved;

[0016] S2. Raise the temperature to 35-55°C, add the main compounding agent with the required mass concentration of 20-54g / L and the auxiliary compounding agent with the mass concentration of 0.01-3.5g / L, and stir until completely dissolved;

[0017] S3, adding the required mass concentration of 0.05-0.65g / L of the compounding additive to the above-mentioned stirred solution, and stirring until completely dissolved;

[0018] S4, maintaining the temperature at 35-55°C and stirring continuously for 2 hours to obtain a cyanide-free silver plating brightener composition stock solution;

[0019] A bright silver plating additive composition is prepared according to the above steps.

[0020] As an optional solution of the present invention, the amount of the cyanide-free silver plating brightener composition stock solution added to the cyanide-free silver plating solution is 8-20 g / L.

[0021] As an optional solution of the present invention, the preparation method of the cyanide-free silver plating solution is as follows:

[0022] In 500 mL of water, silver nitrate with a mass concentration of 40-80 g / L, potassium thiosulfate with a mass concentration of 200-300 g / L, potassium pyrosulfite with a mass concentration of 60-84 g / L, potassium sulfate with a mass concentration of 10-20 g / L, and boric acid with a mass concentration of 20-45 g / L are dissolved, and the prepared non-cyanide silver plating brightener composition stock solution with a mass concentration of 8-20 g / L is added under uniform stirring, the pH is adjusted to 4.2-5.0 with sulfuric acid, and water is added to adjust the pH to 1 L, the working temperature of the non-cyanide silver plating solution is maintained at 25-45° C., and the non-cyanide silver plating solution is obtained by uniform stirring.

[0023] The bright silver plating additive composition and the method for using the bright silver plating additive composition in cyanide-free silver plating provided by the embodiments of the present invention have at least one of the following technical effects:

[0025] 1. The components selected for the bright silver plating additive composition provided by the present invention are all low-toxic or non-toxic compounds, and the preparation steps are simple, and it is easy to realize industrial production;

[0026] 2. The bright silver plating additive composition prepared by the present invention adopts a main compounding agent that is a compound containing S, N, and O di-coordinate atoms, which can form a chelate complex with Ag+ and has a five-membered ring or a six-membered ring structure. Due to the chelate ring effect, the complex is more stable, the electrochemical deposition rate of Ag+ is slowed down, the larger the crystal particles, the more perfect the crystals, the more complete the coating, and the higher the brightness;

[0027] 3. The bright silver plating additive composition prepared by the present invention adopts the synergistic effect of auxiliary complexing agents to further enhance the stability of the complex, so that the crystallization of the coating is more perfect, the brightness and adhesion of the coating are higher, and at the same time, the cathode polarization effect can be increased, and the operable current density range can be widened (0.5-10A / dm2);

[0028] 4. The bright silver plating additive composition prepared by the present invention combines the additive with the impurity ions in the plating solution to form a complex, which improves the potential of the impurity metal, has a significant impurity removal effect, makes the coating crystal more uniform and dense, and improves the wear resistance of the coating;

[0029] 5. The bright silver plating additive composition prepared by the present invention has an anionic surfactant that wets the substrate surface in the plating solution, and the cation is more likely to approach the substrate (material) surface, thereby improving the adhesion between the silver plating layer and the substrate surface, and further improving the uniformity of the plating surface and the brightness of the plating layer;

[0030] 6. The bright silver plating additive composition of the present invention can make the coating mirror-bright and can achieve the same or better brightness effect as cyanide silver plating. The coating performance test found that the coating after electroplating with the bright cyanide-free silver plating solution is not easy to change color, has low brittleness, good adhesion, and can meet the coating requirements of different application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0032] Figure 1 A schematic diagram of test results of a cyanide-free silver plating solution prepared using the bright silver plating additive composition provided by an embodiment of the present invention.

[0033] Figure 2 The bright silver plating additive composition of Examples 1-5 is formulated into a cyanide-free silver plating solution and the actual picture of the electroplating experiment of Comparative Example 1.

[0034] Figure 3 The bright silver plating additive compositions of Examples 1-5 are formulated into cyanide-free silver plating solutions and the adhesion test results of Comparative Example 1.

[0035] Figure 4 The SEM morphology of the coatings prepared from the bright silver plating additive compositions of Examples 1-5 into cyanide-free silver plating solutions and the electroplating experiment of Comparative Example 1.

[0036] Figure 5 The bright silver plating additive compositions of Examples 1-5 are formulated into cyanide-free silver plating solutions and the potassium sulfide test results of Comparative Example 1. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0038] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0041] Embodiment 1:

[0042] A bright silver plating additive composition and a method for using the same in cyanide-free silver plating, comprising the following steps:

[0043] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh sodium dodecylbenzene sulfonate (SDBS) with a required mass concentration of 0.5 g / L and polyethylene glycol-400 with a mass concentration of 1 g / L, and stir in a container until completely dissolved;

[0044] S2, heating to 35°C, adding tea polyphenols with a required mass concentration of 20 g / L and 4-bromoacetate with a mass concentration of 0.1 g / L, and stirring until completely dissolved;

[0045] S3, adding 4-thiazolidine-2-benzoyl urea with a required mass concentration of 0.05 g / L to the above stirred solution, and stirring until completely dissolved;

[0046] S4, maintaining the temperature at 35°C and stirring continuously for 2 hours to obtain the original (concentrated) solution of the cyanide-free silver plating brightener composition;

[0047] A bright silver plating additive composition is prepared according to the above steps.

[0048] The bright silver plating additive composition stock solution of the present invention is added in an amount of 8-20 g / L in a cyanide-free silver plating solution.

[0049] Preparation of non-cyanide silver plating solution: dissolve silver nitrate with a mass concentration of 40 g / L, potassium thiosulfate with a mass concentration of 200 g / L, potassium pyrosulfite with a mass concentration of 60 g / L, potassium sulfate with a mass concentration of 10 g / L, and boric acid with a mass concentration of 20 g / L in about 500 mL of water, add the non-cyanide silver plating brightener composition stock solution with a mass concentration of 8 g / L prepared above under stirring, adjust the pH to 4.2 with sulfuric acid, add water to 1 L, keep the working temperature of the plating solution at 25° C., and stir evenly to obtain a bright non-cyanide silver plating solution;

[0050] Hall cell plating: clean the standard 267mL Hall cell, add a pure silver plate as the anode, accurately measure 250mL of the prepared bright cyanide-free silver plating solution, and add it to the prepared Hall cell.

[0051] The standard brass Hastelloy sheet was electrolytically degreased with 5A current for 1 minute and then rinsed with deionized water. It was then activated with 1g / L hydrochloric acid and cleaned with deionized water. It was then placed in the cathode for electroplating and bubbling. The current density was 0.5A / dm 2 , the electroplating time is 5min;

[0052] Coating performance test: The coating has a silvery white appearance; the coating has slight peeling in the 100-grid test, and the peeling area is less than 5%; the scanning electron microscope shows that the coating is amorphous crystalline particles with uneven arrangement and many pits on the surface; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 18 minutes to change color.

[0053] The test results are detailed in the attached Figure 1 The table shown.

[0054] Embodiment 2:

[0055] A bright silver plating additive composition and a method for using the same in cyanide-free silver plating, comprising the following steps:

[0056] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh the required sodium dodecylbenzene sulfonate (SDBS) with a mass concentration of 1.5 g / L, sodium dodecyl sulfate (SDS) with a mass concentration of 0.5 g / L, sodium hexadecyl sulfonate (AS) with a mass concentration of 0.5 g / L, polyethylene glycol-400 with a mass concentration of 2 g / L, polypropylene glycol-600 with a mass concentration of 1 g / L, and Triton-100 with a mass concentration of 1 g / L, and stir in a container until completely dissolved;

[0057] S2, heating to 40°C, adding 25g / L tea polyphenols, 2g / L linoleic acid, 3g / L 1.6.7-trihydroxyxanthone, 0.01g / L N-(substituted thiazol-2-yl)-chrysanthemumamide, 0.5g / L pterostilbene, and 0.25g / L 4-bromoacetate, and stirring until completely dissolved;

[0058] S3, adding 4-thiazolidine-2-benzoyl urea with a required mass concentration of 0.1 g / L, dithizone with a mass concentration of 0.05 g / L, and resveratrol with a mass concentration of 0.05 g / L to the above stirred solution, and stirring until completely dissolved;

[0059] S4, maintaining the temperature at 40°C and stirring continuously for 2 hours to obtain the original (concentrated) solution of the cyanide-free silver plating brightener composition;

[0060] A bright silver plating additive composition is prepared according to the above steps.

[0061] The bright silver plating additive composition stock solution of the present invention is added in an amount of 8-20 g / L in a cyanide-free silver plating solution.

[0062] Preparation of non-cyanide silver plating solution: dissolve silver nitrate with a mass concentration of 50 g / L, potassium thiosulfate with a mass concentration of 225 g / L, potassium pyrosulfite with a mass concentration of 66 g / L, potassium sulfate with a mass concentration of 12.5 g / L, and boric acid with a mass concentration of 26.25 g / L in about 500 mL of water, add the non-cyanide silver plating brightener composition stock solution with a mass concentration of 11 g / L prepared above under stirring, adjust the pH to 4.4 with sulfuric acid, add water to 1 L, keep the working temperature of the plating solution at 30° C., and stir evenly to obtain a bright non-cyanide silver plating solution;

[0063] Hall cell plating: clean the standard 267mL Hall cell, add a pure silver plate as the anode, accurately measure 250mL of the prepared bright cyanide-free silver plating solution, and add it to the prepared Hall cell.

[0064] The standard brass Hastelloy sheet was electrolytically degreased with 5A current for 1 minute and then rinsed with deionized water. It was then activated with 1g / L hydrochloric acid and cleaned with deionized water. It was then placed in the cathode for electroplating and bubbling. The current density was 2.875A / dm 2 , the electroplating time is 4min;

[0065] Coating performance test: The coating is silvery white in appearance; the coating has no shedding phenomenon in the 100-grid test; the scanning electron microscope shows that the coating crystal particles are uniform and the coating surface is relatively smooth; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 25 minutes to change color.

[0066] The test results are detailed in the attached Figure 1 Table shown.

[0067] Embodiment 3:

[0068] A bright silver plating additive composition and a method for using the same in cyanide-free silver plating, comprising the following steps:

[0069] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh 2.5 g / L sodium dodecylbenzene sulfonate (SDBS), 1 g / L sodium dodecyl sulfate (SDS), 1.3 g / L sodium hexadecyl sulfonate (AS), 3 g / L polyethylene glycol-400, 4 g / L polypropylene glycol-600, and 4 g / L Triton-100 in a container and stir until completely dissolved.

[0070] S2, heating to 45°C, adding 30 g / L tea polyphenols, 4 g / L linoleic acid, 5 g / L 1.6.7-trihydroxyxanthone, 0.13 g / L N-(substituted thiazol-2-yl)-chrysanthemumamide, 1 g / L pterostilbene, and 0.5 g / L 4-bromoacetate, and stirring until completely dissolved;

[0071] S3, adding 4-thiazolidine-2-benzoyl urea with a required mass concentration of 0.15 g / L, dithizone with a mass concentration of 0.075 g / L, and resveratrol with a mass concentration of 0.15 g / L to the above stirred solution, and stirring until completely dissolved;

[0072] S4, maintaining the temperature at 45°C and stirring continuously for 2 hours to obtain the original (concentrated) solution of the cyanide-free silver plating brightener composition;

[0073] A bright silver plating additive composition is prepared according to the above steps.

[0074] The amount of the non-cyanide silver plating brightener composition stock solution added to the non-cyanide silver plating solution is 8-20 g / L.

[0075] Preparation of non-cyanide silver plating solution: dissolve silver nitrate with a mass concentration of 60 g / L, potassium thiosulfate with a mass concentration of 250 g / L, potassium pyrosulfite with a mass concentration of 72 g / L, potassium sulfate with a mass concentration of 15 g / L, and boric acid with a mass concentration of 32.5 g / L in about 500 mL of water, add the non-cyanide silver plating brightener composition stock solution with a mass concentration of 14 g / L prepared above under stirring, adjust the pH to 4.6 with sulfuric acid, add water to 1 L, maintain the working temperature of the plating solution at 35° C., and stir evenly to obtain a bright non-cyanide silver plating solution;

[0076] Hall cell plating: clean the standard 267mL Hall cell, add a pure silver plate as the anode, accurately measure 250mL of the prepared bright cyanide-free silver plating solution, and add it to the prepared Hall cell.

[0077] The standard brass Hastelloy sheet was electrolytically degreased at 5A current for 1 minute and then rinsed with deionized water. It was then activated with 1g / L hydrochloric acid and cleaned with deionized water. It was then placed in the cathode for electroplating and bubbling. The current density was 5.25A / dm 2 , the electroplating time is 3min;

[0078] Coating performance test: The coating has a silvery white appearance; the coating has no shedding phenomenon in the 100-grid test; the scanning electron microscope shows that the coating crystal particles are evenly arranged, and the coating surface is smooth and flat; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 30 minutes for color change.

[0079] The test results are detailed in the attached Figure 1 Table shown.

[0080] Embodiment 4:

[0081] A bright silver plating additive composition and a method for using the same in cyanide-free silver plating, comprising the following steps:

[0082] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh 3.5 g / L sodium dodecylbenzene sulfonate (SDBS), 1.5 g / L sodium dodecyl sulfate (SDS), 2.1 g / L sodium hexadecyl sulfonate (AS), 4 g / L polyethylene glycol-400, 7 g / L polypropylene glycol-600, and 7 g / L Triton-100 in a container and stir until completely dissolved.

[0083] S2, heating to 50°C, adding 35g / L tea polyphenols, 6g / L linoleic acid, 8g / L 1.6.7-trihydroxyxanthone, 0.34g / L N-(substituted thiazol-2-yl)-chrysanthemumamide, 1.5g / L pterostilbene, 0.75g / L 4-bromoacetate, and stirring until completely dissolved; S3, adding 0.2g / L 4-thiazolidine-2-benzoyl urea, 0.1g / L dithizone, and 0.25g / L resveratrol to the above stirred solution, and stirring until completely dissolved;

[0084] S4, maintaining the temperature at 50°C and stirring continuously for 2 hours to obtain the original (concentrated) solution of the cyanide-free silver plating brightener composition;

[0085] A bright silver plating additive composition is prepared according to the above steps.

[0086] The bright silver plating additive composition stock solution of the present invention is added in an amount of 8-20 g / L in a cyanide-free silver plating solution.

[0087] Preparation of non-cyanide silver plating solution: dissolve silver nitrate with a mass concentration of 70 g / L, potassium thiosulfate with a mass concentration of 275 g / L, potassium pyrosulfite with a mass concentration of 78 g / L, potassium sulfate with a mass concentration of 17.5 g / L, and boric acid with a mass concentration of 38.75 g / L in about 500 mL of water, add the non-cyanide silver plating brightener composition stock solution with a mass concentration of 17 g / L prepared above under stirring, adjust the pH to 4.8 with sulfuric acid, add water to 1 L, keep the working temperature of the plating solution at 40° C., and stir evenly to obtain a bright non-cyanide silver plating solution;

[0088] Hall cell plating: clean the standard 267mL Hall cell, add a pure silver plate as the anode, accurately measure 250mL of the prepared bright cyanide-free silver plating solution, and add it to the prepared Hall cell.

[0089] The standard brass Hastelloy sheet was electrolytically degreased with 5A current for 1 minute and then rinsed with deionized water. It was then activated with 1g / L hydrochloric acid and cleaned with deionized water. It was then placed in the cathode for electroplating and bubbling. The current density was 8.125A / dm 2 , the electroplating time is 2min;

[0090] Coating performance test: The coating has a silvery white appearance; the coating has no shedding phenomenon in the 100-grid test; the scanning electron microscope shows that the coating crystal particles are evenly arranged, and the coating surface is smooth and flat; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 30 minutes for color change.

[0091] The test results are detailed in the attached Figure 1 Table shown.

[0092] Embodiment 5:

[0093] A bright silver plating additive composition and a method for using the same in cyanide-free silver plating, comprising the following steps:

[0094] S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh 4.5 g / L sodium dodecylbenzene sulfonate (SDBS), 2 g / L sodium dodecyl sulfate (SDS), 3 g / L sodium hexadecyl sulfonate (AS), 5 g / L polyethylene glycol-400, 10 g / L polypropylene glycol-600, and 10 g / L Triton-100 in a container and stir until completely dissolved.

[0095] S2, heating to 55°C, adding 40g / L tea polyphenols, 4g / L linoleic acid, 3g / L 1.6.7-trihydroxyxanthone, 0.46g / L N-(substituted thiazol-2-yl)-chrysanthemumamide, 2g / L pterostilbene, and 1g / L 4-bromoacetate, stirring until completely dissolved;

[0096] S3, adding 4-thiazolidine-2-benzoyl urea with a required mass concentration of 0.25 g / L and resveratrol with a mass concentration of 0.3 g / L to the above stirred solution, and stirring until completely dissolved;

[0097] S4, maintaining the temperature at 55°C and stirring continuously for 2 hours to obtain the original (concentrated) solution of the cyanide-free silver plating brightener composition;

[0098] A bright silver plating additive composition is prepared according to the above steps.

[0099] The bright silver plating additive composition stock solution of the present invention is added in an amount of 8-20 g / L in a cyanide-free silver plating solution.

[0100] Preparation of non-cyanide silver plating solution: dissolve silver nitrate with a mass concentration of 80 g / L, potassium thiosulfate with a mass concentration of 300 g / L, potassium pyrosulfite with a mass concentration of 84 g / L, potassium sulfate with a mass concentration of 20 g / L, and boric acid with a mass concentration of 45 g / L in about 500 mL of water, add 20 g / L of the non-cyanide silver plating brightener composition stock solution prepared above under stirring, adjust the pH to 5.0 with sulfuric acid, add water to 1 L, keep the working temperature of the plating solution at 45° C., and stir evenly to obtain a bright non-cyanide silver plating solution;

[0101] Hall cell plating: clean the standard 267mL Hall cell, add a pure silver plate as the anode, accurately measure 250mL of the prepared bright cyanide-free silver plating solution, and add it to the prepared Hall cell.

[0102] The standard brass Hastelloy sheet was electrolytically degreased with 5A current for 1 minute and then rinsed with deionized water. It was then activated with 1g / L hydrochloric acid and cleaned with deionized water. It was then placed in the cathode for electroplating and bubbling. The current density was 10A / dm 2 , the electroplating time is 1min;

[0103] Coating performance test: The coating is silvery white in appearance; the coating has no shedding phenomenon in the 100-grid test; the scanning electron microscope shows that the coating crystallization is uneven and the crystal particles are densely arranged; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 25 minutes to change color.

[0104] The test results are detailed in the attached Figure 1 Table shown.

[0105] Comparative Example:

[0106] The cyanide-free silver plating solution prepared by the steps of Example 3 of a cyanide-free silver plating method disclosed in Chinese patent document 201310471133.2 was subjected to a comparative test of electroplating coating with the bright cyanide-free silver plating solution of the present invention.

[0107] Coating performance test: The coating has a yellowish appearance; the coating has fallen off in the 100-grid test, and the falling area is less than 5%; the scanning electron microscope shows that the coating crystals are amorphous crystalline particles, arranged irregularly, with several large pits on the surface and many pores; the coating is immersed in the protective agent working solution for 10 seconds, taken out, washed with water, blown dry, and tested with 2% potassium sulfide for 12 minutes to change color. Figure 1 In the table shown, the appearance color is measured visually; the heat resistance is the color change and peeling phenomenon after baking at 300°C for 1 hour; the adhesion is measured with reference to GB / T9286-2021; the gloss is measured visually; the vulcanization test concentration is 2% and the test temperature is 28°C.

[0108] pass Figure 1 The test results in the table show that the bright silver plating additive composition disclosed by the present invention and the method of using the same in cyanide-free silver plating can make the plating layer brighter and more bonded, and can meet the needs of different application fields.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bright silver plating additive composition, characterized in that: The invention comprises a main compounding agent with a mass concentration of 20-54 g / L, an auxiliary compounding agent with a mass concentration of 0.01-3.5 g / L, a compounding additive with a mass concentration of 0.05-0.65 g / L, an ionic surfactant with a mass concentration of 0.5-10 g / L, a non-ionic surfactant with a mass concentration of 1-25 g / L and the balance of water.

2. A bright silver plating additive composition according to claim 1, characterized in that: The main compounding agent is one or more of tea polyphenols, linoleic acid and 1.6.7-trihydroxyxanthone.

3. A bright silver plating additive composition according to claim 1, characterized in that: The auxiliary compounding agent is one or more of N-(substituted thiazole-2-yl)-chrysanthemum amide, pterostilbene, and 4-bromoacetate phenyl.

4. A bright silver plating additive composition according to claim 1, characterized in that: The compounding additive is one or more of 4-thiazolidine-2-benzoyl urea, dithizone and resveratrol.

5. A bright silver plating additive composition according to claim 1, characterized in that: The anionic surfactant is one or more of sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), and sodium hexadecyl sulfonate (AS).

6. A bright silver plating additive composition according to claim 1, characterized in that: The non-ionic surfactant is one or more of polyethylene glycol-400, polypropylene glycol-600 and Triton-100.

7. A bright silver plating additive composition according to claim 1, characterized in that: The water is one of deionized water, double distilled water and distilled water.

8. A method for using the bright silver plating additive composition according to any one of claims 1 to 7 in cyanide-free silver plating, characterized in that: The method comprises the following steps: S1. Measure 1 / 3 of the predetermined volume of deionized water, weigh the required mass concentration of 0.5-10 g / L of ionic surfactant and the mass concentration of 1-25 g / L of non-ionic surfactant in a container and stir until completely dissolved; S2. Raise the temperature to 35-55°C, add the main compounding agent with the required mass concentration of 20-54g / L and the auxiliary compounding agent with the mass concentration of 0.01-3.5g / L, and stir until completely dissolved; S3, adding the required mass concentration of 0.05-0.65g / L of the compounding additive to the above-mentioned stirred solution, and stirring until completely dissolved; S4, maintaining the temperature at 35-55°C and stirring continuously for 2 hours to obtain a cyanide-free silver plating brightener composition stock solution; A bright silver plating additive composition is prepared according to the above steps.

9. A bright silver plating additive composition according to claim 8, characterized in that: The amount of the non-cyanide silver plating brightener composition stock solution added to the non-cyanide silver plating solution is 8-20 g / L.

10. A bright silver plating additive composition according to claim 9, characterized in that: The cyanide-free silver plating solution preparation method is as follows: In 500 mL of water, silver nitrate with a mass concentration of 40-80 g / L, potassium thiosulfate with a mass concentration of 200-300 g / L, potassium pyrosulfite with a mass concentration of 60-84 g / L, potassium sulfate with a mass concentration of 10-20 g / L, and boric acid with a mass concentration of 20-45 g / L are dissolved, and the prepared non-cyanide silver plating brightener composition stock solution with a mass concentration of 8-20 g / L is added under uniform stirring, the pH is adjusted to 4.2-5.0 with sulfuric acid, and water is added to adjust the pH to 1 L, the working temperature of the non-cyanide silver plating solution is maintained at 25-45° C., and the non-cyanide silver plating solution is obtained by uniform stirring.

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