An additive composition for alkaline cyanide-free zinc plating and a method for preparing the same

Abstract

The application belongs to the technical field of electroplating additives, and discloses a kind of alkaline cyanide-free zinc plating additive composition and its preparation method, the additive is made of alkaline zinc plating open cylinder agent, brightener, purifier, adjusting agent according to specific ratio, each component synergistic effect, realize high bright, strong uniform plating, high stable cyanide-free zinc plating effect.Synthesize four kinds of single agent respectively during preparation, then mix uniformly according to proportion.The application solves the defects of existing alkaline cyanide-free zinc plating additive, such as weak uniform plating ability in low current area, insufficient brightness of plating layer, poor stability of plating solution, low impurity tolerance, etc.The uniform plating ability in low current area reaches more than 94%, the mirror surface brightness of plating layer is more than 96 levels, the tolerance to metal impurities is high, and the bonding force and thickness uniformity of plating layer are excellent.The product is cyanide-free and free of harmful heavy metals throughout the process, which is environmentally friendly and safe, can achieve the brightening and leveling effect of cyanide zinc plating, and has good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of electroplating additive technology, specifically relating to an alkaline cyanide-free zinc plating additive composition and its preparation method. Background Technology

[0002] In the field of metal surface protection, galvanizing is widely used for surface treatment of automotive parts, hardware products, electronic components, and air conditioning pipes for new energy vehicles due to its good corrosion resistance, strong adhesion, and moderate cost. Traditional galvanizing is mainly based on cyanide plating. This process has stable plating solutions, bright and fine coatings, and excellent uniform plating ability, and was once the mainstream choice for high-end electroplating. However, cyanide is a highly toxic substance, posing serious safety hazards during production. Moreover, cyanide-containing wastewater is difficult to treat and has significant environmental harm. The use of cyanide plating has been restricted, and alkaline cyanide-free galvanizing has become the mainstream alternative technology in the industry. Alkaline cyanide-free galvanizing has advantages such as being cyanide-free and environmentally friendly, having a simple plating solution composition, producing fine crystals in the coating, and being suitable for electroplating complex workpieces. It is currently a key development direction in the field of metal surface treatment, and additives, as core components, directly determine the performance of the plating solution and the quality of the coating.

[0003] Currently available alkaline cyanide-free zinc plating additives still suffer from numerous technical defects, failing to meet the demands of high-end manufacturing. Their low-current dispersion and uniform plating capabilities are weak, easily leading to problems such as darkening, missed plating, and uneven coverage in areas like deep holes, blind holes, and corners, making it impossible to guarantee consistent plating for complex parts. The plating brightness and leveling are also insufficient, mostly achieving only a semi-bright effect, far inferior to the mirror-like brightness of cyanide zinc plating, affecting product appearance and added value. Furthermore, some additives are prone to decomposition and precipitation during long-term use, resulting in poor plating solution stability and low impurity tolerance, requiring frequent maintenance and adjustments, increasing production costs. In addition, existing additives have limited functions, lacking synergistic functions such as impurity purification, oxidation resistance, and plating solution environment regulation, making them unsuitable for continuous industrial production. These problems severely restrict the application of alkaline cyanide-free zinc plating processes in high-end fields such as new energy vehicles. Therefore, developing a high-brightness, high-uniformity, and highly stable functional alkaline cyanide-free zinc plating additive has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] To address the problems mentioned in the background art, this invention proposes an alkaline cyanide-free zinc plating additive composition and its preparation method. By optimizing the alkaline zinc plating brightener components and its preparation process, a mirror-like bright coating effect can be achieved, with brightness increased by about 30% compared to existing products, reaching or even surpassing the brightness level of traditional cyanide zinc plating, significantly improving the product's appearance quality and added value.

[0005] The technical solution adopted by this invention to solve its technical problem is: to provide an alkaline cyanide-free zinc plating additive composition, comprising the following components in parts by weight:

[0006] 10-30 parts of alkaline zinc plating starter.

[0007] 5-20 parts of alkaline zinc plating brightener

[0008] 3-15 parts of alkaline zinc plating cleaning agent

[0009] 2-10 parts of alkaline zinc plating conditioner.

[0010] Furthermore, the alkaline zinc plating starter comprises the following raw materials by weight percentage:

[0011] Deionized water 45%~58%,

[0012] 18%~25% cationic quaternary ammonium salt,

[0013] Methyl oxychloroethane 9%~14%,

[0014] Water-soluble cationic polymers 7%~12%,

[0015] Formaldehyde 4%~8%;

[0016] The cationic quaternary ammonium salt includes benzyltriethylammonium chloride, tetrabutylammonium bromide, or dodecyltrimethylammonium chloride; the water-soluble cationic polymer is polyquaternary ammonium salt-2.

[0017] Furthermore, the alkaline zinc plating brightener comprises the following raw materials by weight percentage:

[0018] Deionized water 48%~58%,

[0019] Sodium metabisulfite 10%~15%,

[0020] 18%~25% benzylpyridine carboxylic salt

[0021] Vanillin 10%~16%;

[0022] The benzylpyridine carboxylic salt is a 1-benzylpyridine-3-carboxylic acid salt.

[0023] Furthermore, the alkaline zinc plating purifying agent comprises the following raw materials by weight percentage:

[0024] Deionized water 68%~78%,

[0025] Tetrasodium EDTA 12%~18%,

[0026] Thiourea dioxide 9%~15%.

[0027] Furthermore, the alkaline zinc plating conditioner comprises the following raw materials by weight percentage:

[0028] 30%~40% deionized water

[0029] Sodium silicate 40%~50%,

[0030] Sodium potassium tartrate 15%~25%.

[0031] A method for preparing an alkaline cyanide-free zinc plating additive composition involves preparing an alkaline zinc plating starter, an alkaline zinc plating brightener, an alkaline zinc plating purifier, and an alkaline zinc plating conditioner, and then mixing the obtained reagents evenly according to the specified ratio to obtain the alkaline cyanide-free zinc plating additive composition.

[0032] Furthermore, the preparation of the alkaline zinc plating starter includes the following steps:

[0033] (1) Add deionized water to the reactor and control the temperature at 20℃-30℃;

[0034] (2) Add the cationic quaternary ammonium salt and stir for 30-40 minutes;

[0035] (3) Add methyl oxychloroethane and stir for 30-40 minutes until fully dissolved and mixed;

[0036] (4) Add water-soluble cationic polymer and stir for 20-30 minutes;

[0037] (5) Finally, add formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain alkaline zinc plating starter.

[0038] Furthermore, the preparation of the alkaline zinc plating brightener includes the following steps:

[0039] (1) Add deionized water to the reactor and heat to 80℃~100℃;

[0040] (2) Add sodium metabisulfite while stirring, and stir for 30 to 40 minutes until fully dissolved;

[0041] (3) Keep at 80℃~100℃, add vanillin while stirring, and keep at 80℃ for 120 minutes while stirring;

[0042] (4) Cool down to below 40°C, add benzylpyridine carboxylic acid salt while stirring, stir until the system is clear and uniform, cool to room temperature, and obtain alkaline zinc plating brightener.

[0043] Furthermore, the preparation of the alkaline zinc plating purifying agent includes the following steps:

[0044] (1) Add deionized water to the reactor and stir at room temperature;

[0045] (2) Add tetrasodium ethylenediaminetetraacetate and stir for 30 to 40 minutes until fully dissolved;

[0046] (3) Add thiourea dioxide and stir until completely dissolved and mixed to obtain an alkaline zinc plating purifier.

[0047] Furthermore, the preparation of the alkaline zinc plating conditioner includes the following steps:

[0048] (1) Add deionized water to the reactor and stir at room temperature;

[0049] (2) Add sodium silicate and stir for 30 to 40 minutes until fully dissolved;

[0050] (3) Add potassium sodium tartrate and stir until completely dissolved and mixed to obtain alkaline zinc plating conditioner.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] (1) By optimizing the components of alkaline zinc plating brightener and its preparation process, the present invention can achieve a mirror-like bright coating effect, with brightness increased by about 30% compared with existing products, reaching or even exceeding the brightness level of traditional cyanide zinc plating, significantly improving the appearance quality and added value of products.

[0053] (2) The starter agent in the additive composition of the present invention is a cationic quaternary ammonium salt, methyl oxychloroethane and a water-soluble cationic polymer, which can form a stable adsorption film on the cathode surface, improve the metal ion discharge process, make the coating more uniformly distributed in the low current density area, and improve the plating capacity in the low potential area by about 40%, effectively solving the problems of missed plating, darkening and uneven coverage that are common in existing products on complex workpiece surfaces.

[0054] (3) In this invention, the purifying agent can effectively complex metal impurity ions in the plating solution, reducing the impact of impurities on the coating quality; the adjusting agent has antioxidant and calcium and magnesium ion removal effects, preventing the oxidative decomposition of plating solution components, significantly improving the long-term operational stability of the plating solution, and reducing maintenance frequency and cost.

[0055] (4) All components of this invention are free of cyanide and harmful heavy metals, making it suitable for high-end fields such as air conditioning pipes for new energy vehicles, automotive parts, and electronic components. It has good environmental friendliness and industrial application prospects.

[0056] (5) The present invention combines the starter, brightener, purifier and adjuster in a specific ratio. The components have a good synergistic effect, which not only ensures the rapid brightening and leveling of the coating, but also stabilizes the plating solution, purifies impurities and adjusts the plating solution environment, forming a complete and stable alkaline cyanide-free zinc plating additive system that meets the needs of continuous and large-scale production. Attached Figure Description

[0057] Figure 1A comparison chart showing the electroplating effects of commercially available conventional alkaline cyanide-free zinc plating additives and the alkaline cyanide-free zinc plating additive of this invention on high-carbon black steel. Figure 2 The image shows the effect of electroplating using the alkaline cyanide-free zinc plating additive of this invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Example 1:

[0060] (1) Preparation of alkaline zinc plating starter

[0061] Weigh the following by weight percentage: 52% deionized water, 22% benzyltriethylammonium chloride, 12% methyl oxychloroethane, 29% polyquaternium salt-2, and 5% formaldehyde. Add the deionized water to the reactor and control the temperature at 25°C; add the benzyltriethylammonium chloride and stir for 35 minutes; add the methyl oxychloroethane and stir for 35 minutes until fully dissolved and mixed; add the polyquaternium salt-2 and stir for 25 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0062] (2) Preparation of alkaline zinc plating brightener

[0063] Weigh the following by mass percentage: 53% deionized water, 12% sodium metabisulfite, 21% 1-benzylpyridine-3-carboxylate, and 14% vanillin. Add the deionized water to the reaction vessel and heat to 90°C; add the sodium metabisulfite while stirring, and stir for 35 minutes until fully dissolved; maintain the temperature at 90°C, add the vanillin, and stir for 120 minutes; cool to 35°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0064] (3) Preparation of alkaline zinc plating purifying agent

[0065] Weigh the following by mass percentage: 73% deionized water, 15% tetrasodium ethylenediaminetetraacetate, and 12% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 35 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0066] (4) Preparation of alkaline zinc plating modifier

[0067] Weigh the following by weight percentage: 35% deionized water, 45% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 35 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating conditioner.

[0068] (5) Preparation of additive composition

[0069] Weigh out the following components by weight: 20 parts of alkaline zinc plating starter, 12 parts of alkaline zinc plating brightener, 9 parts of alkaline zinc plating purifier, and 6 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0070] like Figure 1 and Figure 2 As shown, a comparative plating test was conducted using high-carbon black steel as the test substrate, and the alkaline cyanide-free zinc plating additive composition prepared in Example 1 was used for electroplating. Figure 1 The middle right half is a commercially available alkaline cyanide-free zinc plating additive electroplating sample. The workpiece has a black base material and the corresponding low current area of ​​the plating layer is grayish and dark, the plating layer is unevenly bright, and the corners and deep recesses have prominent plating defects and hazy surface. Figure 1 The left half shows the electroplating sample of the additive composition of this invention. The high-carbon black-skinned workpieces of the same batch exhibit a mirror-like bright coating overall. The coating is uniform and full in low-current areas, corners, and corresponding parts of the black-skinned substrate, without any dullness or missed plating defects. For high-carbon black-skinned, difficult-to-plate substrates, the brightener of this invention, relying on the synergistic advantages of the combined use of a plating starter, purifier, and modifier, demonstrates a significant breakthrough in achieving smooth and bright plating on these substrates. The electroplating performance improvement trend is similar for other conventional steel substrates. Figure 2 The electroplated finished product with the additive of this invention is shown separately. The entire plate has a smooth, mirror-like coating with consistent thickness and no pitting or color difference, further proving that the coating of this additive has excellent appearance and overall performance, and is suitable for the industrial mass production of complex and difficult-to-plate workpieces.

[0071] Example 2:

[0072] (1) Preparation of alkaline zinc plating starter

[0073] Weigh the following by weight percentage: 45% deionized water, 25% tetrabutylammonium bromide, 14% methyl oxychloroethane, 12% polyquaternium salt-2, and 4% formaldehyde. Add the deionized water to the reactor and control the temperature at 20°C; add the tetrabutylammonium bromide and stir for 40 minutes; add the methyl oxychloroethane and stir for 40 minutes until fully dissolved and mixed; add the polyquaternium salt-2 and stir for 30 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0074] (2) Preparation of alkaline zinc plating brightener

[0075] Weigh the following by mass percentage: 48% deionized water, 15% sodium metabisulfite, 25% 1-benzylpyridine-3-carboxylate, and 12% vanillin. Add the deionized water to the reaction vessel and heat to 80°C; add the sodium metabisulfite while stirring, and stir for 40 minutes until fully dissolved; maintain the temperature at 80°C, add the vanillin, and stir for 120 minutes; cool to 30°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0076] (3) Preparation of alkaline zinc plating purifying agent

[0077] Weigh the following by mass percentage: 68% deionized water, 18% tetrasodium ethylenediaminetetraacetate, and 14% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 40 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0078] (4) Preparation of alkaline zinc plating modifier

[0079] Weigh the following by weight percentage: 30% deionized water, 50% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 40 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating modifier.

[0080] (5) Preparation of additive composition

[0081] Weigh out the following components by weight: 10 parts of alkaline zinc plating starter, 5 parts of alkaline zinc plating brightener, 3 parts of alkaline zinc plating purifier, and 2 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0082] Example 3:

[0083] (1) Preparation of alkaline zinc plating starter

[0084] Weigh the following by weight percentage: 58% deionized water, 18% dodecyltrimethylammonium chloride, 9% methyl oxychloroethane, 27% polyquaternium salt, and 8% formaldehyde. Add the deionized water to the reactor and control the temperature at 30°C; add the dodecyltrimethylammonium chloride and stir for 30 minutes; add the methyl oxychloroethane and stir for 30 minutes until fully dissolved and mixed; add the polyquaternium salt and stir for 20 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0085] (2) Preparation of alkaline zinc plating brightener

[0086] Weigh the following by mass percentage: 58% deionized water, 10% sodium metabisulfite, 18% 1-benzylpyridine-3-carboxylate, and 14% vanillin. Add the deionized water to the reaction vessel and heat to 100°C; add the sodium metabisulfite while stirring, and stir for 30 minutes until fully dissolved; maintain the temperature at 100°C, add the vanillin, and stir for 120 minutes; cool to 40°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0087] (3) Preparation of alkaline zinc plating purifying agent

[0088] Weigh the following by mass percentage: 78% deionized water, 12% tetrasodium ethylenediaminetetraacetate, and 10% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 30 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0089] (4) Preparation of alkaline zinc plating modifier

[0090] Weigh the following by weight percentage: 40% deionized water, 40% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 30 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating modifier.

[0091] (5) Preparation of additive composition

[0092] Weigh out the following components by weight: 30 parts of alkaline zinc plating starter, 20 parts of alkaline zinc plating brightener, 15 parts of alkaline zinc plating purifier, and 10 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0093] Example 4:

[0094] (1) Preparation of alkaline zinc plating starter

[0095] Weigh the following by weight percentage: 50% deionized water, 20% benzyltriethylammonium chloride, 11% methyl oxychloroethane, 10% polyquaternium salt-2, and 9% formaldehyde. Add the deionized water to the reactor and control the temperature at 25°C; add benzyltriethylammonium chloride and stir for 35 minutes; add methyl oxychloroethane and stir for 35 minutes until fully dissolved and mixed; add polyquaternium salt-2 and stir for 25 minutes; finally, add formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0096] (2) Preparation of alkaline zinc plating brightener

[0097] Weigh the following by weight percentage: 55% deionized water, 13% sodium metabisulfite, 20% 1-benzylpyridine-3-carboxylate, and 12% vanillin. Add the deionized water to the reaction vessel and heat to 85°C; add the sodium metabisulfite while stirring, and stir for 35 minutes until fully dissolved; maintain the temperature at 85°C, add the vanillin, and stir for 120 minutes; cool to 35°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0098] (3) Preparation of alkaline zinc plating purifying agent

[0099] Weigh the following by mass percentage: 70% deionized water, 16% tetrasodium ethylenediaminetetraacetate, and 14% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 35 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0100] (4) Preparation of alkaline zinc plating modifier

[0101] Weigh the following by weight percentage: 32% deionized water, 48% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 35 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating conditioner.

[0102] (5) Preparation of additive composition

[0103] Weigh out the following components by weight: 15 parts of alkaline zinc plating starter, 8 parts of alkaline zinc plating brightener, 6 parts of alkaline zinc plating purifier, and 4 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0104] Example 5:

[0105] (1) Preparation of alkaline zinc plating starter

[0106] Weigh the following by weight percentage: 55% deionized water, 21% tetrabutylammonium bromide, 10% methyl oxychloroethane, 28% polyquaternium salt-2, and 6% formaldehyde. Add the deionized water to the reactor and control the temperature at 28°C; add the tetrabutylammonium bromide and stir for 32 minutes; add the methyl oxychloroethane and stir for 32 minutes until fully dissolved and mixed; add the polyquaternium salt-2 and stir for 22 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0107] (2) Preparation of alkaline zinc plating brightener

[0108] Weigh the following by mass percentage: 50% deionized water, 14% sodium metabisulfite, 22% 1-benzylpyridine-3-carboxylate, and 14% vanillin. Add the deionized water to the reaction vessel and heat to 95°C; add the sodium metabisulfite while stirring, and stir for 32 minutes until fully dissolved; maintain the temperature at 95°C, add the vanillin, and stir for 120 minutes; cool to 38°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0109] (3) Preparation of alkaline zinc plating purifying agent

[0110] Weigh the following by mass percentage: 75% deionized water, 14% tetrasodium ethylenediaminetetraacetate, and 11% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 32 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0111] (4) Preparation of alkaline zinc plating modifier

[0112] Weigh the following by weight percentage: 38% deionized water, 42% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 32 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating conditioner.

[0113] (5) Preparation of additive composition

[0114] Weigh out the following components by weight: 25 parts of alkaline zinc plating starter, 15 parts of alkaline zinc plating brightener, 12 parts of alkaline zinc plating purifier, and 8 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0115] Example 6:

[0116] (1) Preparation of alkaline zinc plating starter

[0117] Weigh the following by weight percentage: 48% deionized water, 23% dodecyltrimethylammonium chloride, 13% methyl oxychloroethane, 29% polyquaternium salt-2, and 7% formaldehyde. Add the deionized water to the reactor and control the temperature at 22°C; add the dodecyltrimethylammonium chloride and stir for 38 minutes; add the methyl oxychloroethane and stir for 38 minutes until fully dissolved and mixed; add the polyquaternium salt-2 and stir for 28 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0118] (2) Preparation of alkaline zinc plating brightener

[0119] Weigh the following by mass percentage: 52% deionized water, 11% sodium metabisulfite, 23% 1-benzylpyridine-3-carboxylate, and 14% vanillin. Add the deionized water to the reaction vessel and heat to 90°C; add the sodium metabisulfite while stirring, and stir for 38 minutes until fully dissolved; maintain the temperature at 90°C, add the vanillin, and stir for 120 minutes; cool to 32°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0120] (3) Preparation of alkaline zinc plating purifying agent

[0121] Weigh the following by mass percentage: 72% deionized water, 17% tetrasodium ethylenediaminetetraacetate, and 11% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 38 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0122] (4) Preparation of alkaline zinc plating modifier

[0123] Weigh the following by weight percentage: 34% deionized water, 46% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 38 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating modifier.

[0124] (5) Preparation of additive composition

[0125] Weigh out the following components by weight: 18 parts of alkaline zinc plating starter, 10 parts of alkaline zinc plating brightener, 8 parts of alkaline zinc plating purifier, and 5 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0126] Example 7:

[0127] (1) Preparation of alkaline zinc plating starter

[0128] Weigh the following by weight percentage: 53% deionized water, 19% benzyltriethylammonium chloride, 12% methyl oxychloroethane, 11% polyquaternium salt-2, and 5% formaldehyde. Add the deionized water to the reactor and control the temperature at 26°C; add the benzyltriethylammonium chloride and stir for 34 minutes; add the methyl oxychloroethane and stir for 34 minutes until fully dissolved and mixed; add the polyquaternium salt-2 and stir for 24 minutes; finally, add the formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain the alkaline zinc plating starter.

[0129] (2) Preparation of alkaline zinc plating brightener

[0130] Weigh the following by mass percentage: 56% deionized water, 12% sodium metabisulfite, 19% 1-benzylpyridine-3-carboxylate, and 13% vanillin. Add the deionized water to the reaction vessel and heat to 88°C; add the sodium metabisulfite while stirring, and stir for 34 minutes until fully dissolved; maintain the temperature at 88°C, add the vanillin, and stir for 120 minutes; cool to 36°C, add the 1-benzylpyridine-3-carboxylate, and stir until the system is clear and homogeneous; cool to room temperature to obtain the alkaline zinc plating brightener.

[0131] (3) Preparation of alkaline zinc plating purifying agent

[0132] Weigh the following by mass percentage: 76% deionized water, 13% tetrasodium ethylenediaminetetraacetate, and 11% thiourea dioxide. Add the deionized water to the reaction vessel and stir at room temperature; add the tetrasodium ethylenediaminetetraacetate and stir for 34 minutes until fully dissolved; add the thiourea dioxide and stir until completely dissolved and mixed to obtain the alkaline zinc plating purifying agent.

[0133] (4) Preparation of alkaline zinc plating modifier

[0134] Weigh the following by weight percentage: 36% deionized water, 44% sodium silicate, and 20% potassium sodium tartrate. Add the deionized water to the reaction vessel and stir at room temperature; add the sodium silicate and stir for 34 minutes until fully dissolved; add the potassium sodium tartrate and stir until completely dissolved and mixed to obtain the alkaline zinc plating modifier.

[0135] (5) Preparation of additive composition

[0136] Weigh out the following components by weight: 22 parts of alkaline zinc plating starter, 14 parts of alkaline zinc plating brightener, 10 parts of alkaline zinc plating purifier, and 7 parts of alkaline zinc plating conditioner. Mix and stir evenly to obtain an alkaline cyanide-free zinc plating additive composition.

[0137] Table 1 shows the performance test results for Examples 1-7.

[0138]

[0139] This invention, through optimization of the formulation and precise control of the preparation process of alkaline zinc plating starter, brightener, purifying agent, and conditioning agent, yields a series of alkaline cyanide-free zinc plating additive compositions. Performance test data from Examples 1 to 7 show that the obtained additives achieve a plating uniformity of 94%–96% in the low current range, a mirror brightness level of 96–98, and a current efficiency of 86%–89%. It enables continuous 24-hour production with stable operation for ≥330 days per year. It also improves the performance of Fe... 3+The product exhibits impurity tolerance up to 150 mg / L, with coating adhesion reaching grade 5B without peeling, and thickness uniformity of 92%~95%. Overall, the product combines advantages such as high brightness, strong uniform plating, high stability, and resistance to impurities. It effectively solves problems such as darkening in low-area areas, missed plating, insufficient brightness, and easy decomposition of plating solutions associated with existing cyanide-free zinc plating additives. Environmentally friendly, cyanide-free, and non-toxic, it can completely replace cyanide zinc plating systems. Suitable for large-scale electroplating production of high-end precision components such as air conditioning pipes for new energy vehicles, automotive parts, and electronic components, it possesses excellent practical performance and broad industrialization prospects.

[0140] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An alkaline, cyanide-free zinc plating additive composition, characterized in that, The components include the following parts by weight: 10-30 parts of alkaline zinc plating starter. 5-20 parts of alkaline zinc plating brightener 3-15 parts of alkaline zinc plating cleaning agent 2-10 parts of alkaline zinc plating conditioner.

2. The alkaline cyanide-free zinc plating additive composition according to claim 1, characterized in that, The alkaline zinc plating starter comprises the following raw materials by weight percentage: Deionized water 45%~58%, 18%~25% cationic quaternary ammonium salt, Methyl oxychloroethane 9%~14%, Water-soluble cationic polymers 7%~12%, Formaldehyde 4%~8%; The cationic quaternary ammonium salt includes benzyltriethylammonium chloride, tetrabutylammonium bromide, or dodecyltrimethylammonium chloride; the water-soluble cationic polymer is polyquaternary ammonium salt-2.

3. The alkaline cyanide-free zinc plating additive composition according to claim 1, characterized in that, The alkaline zinc plating brightener comprises the following raw materials by weight percentage: Deionized water 48%~58%, Sodium metabisulfite 10%~15%, 18%~25% benzylpyridine carboxylic salt Vanillin 10%~16%; The benzylpyridine carboxylic salt is a 1-benzylpyridine-3-carboxylic acid salt.

4. The alkaline cyanide-free zinc plating additive composition according to claim 1, characterized in that, The alkaline zinc plating purifying agent comprises the following raw materials by mass percentage: Deionized water 68%~78%, Tetrasodium EDTA 12%~18%, Thiourea dioxide 9%~15%.

5. The alkaline cyanide-free zinc plating additive composition according to claim 1, characterized in that, The alkaline zinc plating modifier comprises the following raw materials by weight percentage: 30%~40% deionized water Sodium silicate 40%~50%, Sodium potassium tartrate 15%~25%.

6. A method for preparing an alkaline, cyanide-free zinc plating additive composition, characterized in that, Alkaline zinc plating starter, alkaline zinc plating brightener, alkaline zinc plating purifier, and alkaline zinc plating conditioner are prepared separately, and then the obtained reagents are mixed evenly according to the ratio to obtain the alkaline cyanide-free zinc plating additive composition.

7. The method for preparing an alkaline cyanide-free zinc plating additive composition according to claim 6, characterized in that, The preparation of the alkaline zinc plating starter includes the following steps: (1) Add deionized water to the reactor and control the temperature at 20℃-30℃; (2) Add the cationic quaternary ammonium salt and stir for 30-40 minutes; (3) Add methyl oxychloroethane and stir for 30-40 minutes until fully dissolved and mixed; (4) Add water-soluble cationic polymer and stir for 20-30 minutes; (5) Finally, add formaldehyde and stir for 60 minutes until completely dissolved and mixed to obtain alkaline zinc plating starter.

8. The method for preparing an alkaline cyanide-free zinc plating additive composition according to claim 6, characterized in that, The preparation of the alkaline zinc plating brightener includes the following steps: (1) Add deionized water to the reactor and heat to 80℃~100℃; (2) Add sodium metabisulfite while stirring, and stir for 30 to 40 minutes until fully dissolved; (3) Keep at 80℃~100℃, add vanillin while stirring, and keep at 80℃ for 120 minutes while stirring; (4) Cool down to below 40°C, add benzylpyridine carboxylic acid salt while stirring, stir until the system is clear and uniform, cool to room temperature, and obtain alkaline zinc plating brightener.

9. The method for preparing an alkaline cyanide-free zinc plating additive composition according to claim 6, characterized in that, The preparation of the alkaline zinc plating purifying agent includes the following steps: (1) Add deionized water to the reactor and stir at room temperature; (2) Add tetrasodium ethylenediaminetetraacetate and stir for 30 to 40 minutes until fully dissolved; (3) Add thiourea dioxide and stir until completely dissolved and mixed to obtain an alkaline zinc plating purifier.

10. The method for preparing an alkaline cyanide-free zinc plating additive composition according to claim 6, characterized in that, The preparation of the alkaline zinc plating conditioner includes the following steps: (1) Add deionized water to the reactor and stir at room temperature; (2) Add sodium silicate and stir for 30 to 40 minutes until fully dissolved; (3) Add potassium sodium tartrate and stir until completely dissolved and mixed to obtain alkaline zinc plating conditioner.

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