CN113818056B - Iminodisuccinic acid cyanide-free silver plating process additive and application method thereof - Google Patents

Abstract

The invention belongs to the electroplating technology, and relates to an iminodisuccinic acid cyanide-free silver plating process additive and a use method thereof. According to the invention, the nicotinic acid, the nicotinamide and the derivatives thereof are added into the plating solution to completely remove the network structure formed by the complexing agent in the plating solution, so that the conductivity and the stability of the plating solution are improved; the conductivity and stability of the iminodisuccinic acid plating solution and the quality of the silver plating layer are improved by adding the composite brightening agent mainly comprising iminodisuccinic acid-citric acid copolymer; meanwhile, all organic substances used by the additive are biodegradable materials, and the harm to the environment and human bodies is small.

Description

A kind of iminodisuccinic acid cyanide-free silver plating process additive and using method

technical field

The invention belongs to electroplating technology, and relates to an iminodisuccinic acid cyanide-free silver plating process additive and a use method.

Background technique

As the country's requirements for environmental protection are getting higher and higher, the cyanide electroplating process, which has serious safety hazards to the human body, needs to be replaced by the safe and environmentally friendly cyanide-free electroplating process. Although the current cyanide-free electroplating process already has thiosulfate system, sulfosalicylic acid system, NS silver plating system, nicotinic acid silver plating system, hydantoin system, iminodisuccinic acid system, etc., among which iminodisuccinic acid In the system, iminodisuccinic acid and its metal salts are used as complexing agents for metallic silver. In CN102021613A (electrolyte composition), it was first reported in 2009 that iminodisuccinic acid derivatives were used as complexing agents for cyanide-free silver plating. This patent pointed out that iminodisuccinic acid derivatives can be used as a separate metal silver ion complex It can also act synergistically with other complexing agents such as hydantoin. Iminodisuccinic acid and its metal salts are a new type of green and environmentally friendly alkaline complexing agent, which has the characteristics of phosphorus-free, non-toxic, pollution-free and easy to biodegrade. The chelating ability of magnesium, zinc and other transition metal ions is very strong, especially the chelating ability of copper, iron, manganese, nickel and other heavy metal elements exceeds that of common chelating agents such as EDTA. mixture. The current cyanide-free silver plating system of iminodisuccinic acid derivatives cannot be applied in large quantities. The main problems are as follows: when iminodisuccinic acid derivatives are used alone as silver plating additives, hydrogen bonds will be formed between complexing agents, which makes it difficult to form large volumes. Moving network structure, which will lead to poor conductivity of the plating solution, and then make the upper limit of available current density of the plating solution smaller; when iminodisuccinic acid derivatives are used in conjunction with auxiliary complexing agents such as hydantoin, because Hydantoin can form hydrogen bonds by itself in the plating solution, so the silver ions in the plating solution cannot completely generate composite silver ions with a molar ratio of two complexing agents of 1:1, and cannot completely remove the network structure in the plating solution. Moreover, hydantoins still have high potential safety hazards to the human body and the environment. Therefore, it is necessary to develop a completely environmentally friendly and efficient iminodisuccinic acid cyanide-free silver plating process. Among them, nicotinic acid, nicotinamide and their derivatives have low ability to form hydrogen bonds in the plating solution, and can be used as auxiliary complexing agents for breaking hydrogen bonds in the plating solution. In addition, when there is no brightener in the plating solution, the quality of the coating cannot meet the requirements, so it is necessary to improve the quality of the coating by adding a suitable brightener, and the copolymer of iminodisuccinic acid and citric acid is a good brightener .

Contents of the invention

The purpose of the invention is to: propose an environmentally friendly and efficient iminodisuccinic acid cyanide-free silver plating process additive, by adding nicotinic acid, nicotinamide and derivatives thereof to completely remove the network structure formed by the complexing agent in the plating solution, thereby improving The conductivity and stability of the plating solution; and the quality of the plating layer is improved by adding a composite brightener based on iminodisuccinic acid-citric acid copolymer. At the same time, all organic substances used in additives are biodegradable materials, which have little harm to the environment and human body.

The technical scheme of the present invention is: an iminodisuccinic acid cyanide-free silver plating process additive, comprising the following components:

a. Iminodisuccinic acid and its derivative co-complexing agent, including silver ion effective complexing components, ammonium sulfate, potassium hydroxide, potassium carbonate, solvent is water; the mass of silver ion effective complexing components and the total mass of the solution The percentage is 50～60%; The quality of ammonium sulfate and the percentage of total solution mass are 5～10%; The quality of potassium hydroxide and the percentage of solution total mass are 5～10%; The percentage is 5-10%, and the solvent is the mass balance of the solution;

b. Combined brightener, including polyethylene glycol 6000, iminodisuccinic acid-citric acid copolymer, alkyl glycoside, solvent is water; the percentage of the mass of polyethylene glycol 6000 and the total mass of the solution is 5-10% The mass of the iminodisuccinic acid-citric acid copolymer is 60-70% of the total mass of the solution; the mass of the alkyl glycoside is 20-35% of the total mass of the solution, and the solvent is the balance of the mass of the solution.

The silver ion effective complexing component refers to a reagent that can convert the silver ion in the plating solution into iminodisuccinic acid and its derivatives and the co-complexing agent silver ion effective complexing component to form a composite silver ion with a molar ratio of 1:1 .

The pH of the iminodisuccinic acid and its derivative co-complexing agent is 8.5-10.

The silver ion is effectively complexed into one or more of nicotinic acid, nicotinamide and derivatives thereof.

The pH of the combined brightener is 7.5-10.

The preparation method of the iminodisuccinic acid-citric acid copolymer in the combined brightener is to weigh 50g of iminodisuccinic acid, 10g of citric acid, and 20ml of water in a container, heat it to 80-100°C in a water bath, and react After 10 minutes, add an aqueous ammonia solution with pH = 11 to make the volume to 500ml.

The nicotinic acid, nicotinamide and derivatives thereof, iminodisuccinic acid-citric acid copolymer are all biodegradable materials.

The using method of the iminodisuccinic acid cyanide-free silver plating process additive, the iminodisuccinic acid and its derivatives co-complexing agent is added with the iminodisuccinic acid and its derivatives into the alkaline solution and stirred until completely dissolved, adjusted pH to alkaline; add silver salt solution dissolved in water, and stir until the solution is completely uniform; add combined brightener and buffer, and stir until completely dissolved; add water to volume, and adjust pH.

The silver salt solution is silver nitrate or silver methanesulfonate solution.

The buffering agent is one or more of carbonate, citrate and methanesulfonate.

The advantages of the present invention are: the present invention completely removes the network structure formed by the complexing agent in the plating solution by adding nicotinic acid, nicotinamide and their derivatives, thereby improving the conductivity and stability of the plating solution; The composite brightener based on acid-citric acid copolymer improves the conductivity and stability of the iminodisuccinic acid plating solution and the quality of the silver coating; at the same time, all organic substances used in additives are biodegradable materials, which are harmful to the environment and There is very little harm to the human body.

Detailed ways

The present invention will be described in further detail below.

An environmentally friendly and efficient iminodisuccinic acid cyanide-free silver plating process additive,

a. Iminodisuccinic acid and its derivative co-complexing agent (the solute is silver ion effective complexing component, ammonium sulfate, potassium hydroxide, potassium carbonate, the solvent is water, and the pH is 8.5-10. Among them, silver ion Effective complexation is divided into nicotinic acid, nicotinamide and its derivatives, the percentage of its mass to the total mass of the solution is 50-60%; the mass of ammonium sulfate to the percentage of the total mass of the solution is 5-10%; the mass of potassium hydroxide The percentage with the total mass of the solution is 5～10%; the percentage of the quality of potassium carbonate and the total mass of the solution is 5～10%, and the solvent is the solution mass surplus.)

B. combination brightener (its solute is Polyethylene Glycol 6000, iminodisuccinic acid-citric acid copolymer, alkyl glucoside, and solvent is water. The percentage of the mass of Polyethylene Glycol 6000 and the total mass of solution is 5～ 10%; the percentage of the mass of iminodisuccinic acid-citric acid copolymer to the total mass of the solution is 60-70%; the percentage of the mass of alkyl glycoside to the total mass of the solution is 20-35%, and the solvent is the balance of the mass of the solution The preparation method of the iminodisuccinic acid-citric acid copolymer is as follows: weigh 50g of iminodisuccinic acid, 10g of citric acid, and 20ml of water in a container, heat to 80-100°C in a water bath, and react for 10min. Add ammoniacal aqueous solution with pH = 11 to make the volume to 500ml.) The pH of the combined brightener is 7.5-10.

The working principle of the present invention is: nicotinic acid, nicotinamide and derivatives thereof have low ability to form hydrogen bonds in the plating solution, and can be used as auxiliary complexing agents for breaking hydrogen bonds in the plating solution; iminodisuccinic acid and citric acid The formed copolymer iminodisuccinic acid-citric acid copolymer can greatly improve the cathodic polarization ability of the plating solution, and make the plating layer bright and fine.

The preparation method of iminodisuccinic acid and its derivative co-complexing agent is: weigh iminodisuccinic acid and potassium hydroxide, then dissolve the weighed solute in water and stir until completely dissolved; then weigh the remaining solute and add Stir until dissolved; finally add water to volume.

The preparation method of the combined brightener is as follows: weigh all the solutes, add an appropriate amount of water and stir until dissolved.

The configuration method of the silver plating solution is: weigh iminodisuccinic acid and its derivatives, iminodisuccinic acid and its derivative co-complexing agent, add alkaline solution and stir until completely dissolved, adjust pH to alkaline; add Use water-dissolved silver salt solution, stir until the solution is completely uniform; add combined brightener, buffer and other substances, stir until completely dissolved; add water to constant volume, and adjust pH. The silver salt solution is silver nitrate or silver methanesulfonate solution; the buffer is one or more of carbonate, citrate, and methanesulfonate.

Example 1

The main salt formula of the electroplating solution is as follows: silver nitrate: 30g/L; potassium hydroxide: 50g/L; iminodisuccinic acid: 100g/L; potassium carbonate: 60g/L.

Iminodisuccinic acid and its derivative co-complexing agent: 300ml/L (niacin 500g/L; ammonium sulfate 80g/L; potassium hydroxide 80g/L; potassium carbonate 80g/L).

Combined brightener: 15ml (polyethylene glycol 6000 20g/L, iminodisuccinic acid-citric acid copolymer 200g/L, alkyl glycoside 40g/L).

Example 2

The main salt formula of the electroplating solution is as follows: silver nitrate: 30g/L; potassium hydroxide: 50g/L; iminodisuccinic acid: 100g/L; potassium carbonate: 60g/L.

Iminodisuccinic acid and its derivatives co-complexing agent: 300ml/L (nicotinamide 550g/L; ammonium sulfate 60g/L; potassium hydroxide 80g/L; potassium carbonate 60g/L)

Combined brightener: 15ml (polyethylene glycol 6000 20g/L, iminodisuccinic acid-citric acid copolymer 250g/L, alkyl glycoside 40g/L).

Example 3

The main salt formula of the electroplating solution is as follows: silver nitrate: 30g/L; potassium hydroxide: 50g/L; iminodisuccinic acid: 100g/L; potassium carbonate: 60g/L.

Iminodisuccinic acid and its derivatives co-complexing agent: 300ml/L (nicotinic acid 200g/L; nicotinamide 250g/L; ammonium sulfate 60g/L; potassium hydroxide 80g/L; potassium carbonate 60g/L)

Combined brightener: 15ml (polyethylene glycol 6000 20g/L, iminodisuccinic acid-citric acid copolymer 250g/L, alkyl glycoside 40g/L)

Performance test results of the coatings in Examples 1, 2, and 3 above: the coatings are smooth in appearance, showing semi-bright silvery white with a slight metallic luster, fine and uniform crystallization, and no nodules, burrs, bubbling, cracks and other defects. Take 304 stainless steel and plate it with silver according to this process, the thickness of the coating is 8-12 μm, and conduct a cross-cut test according to the scratch method to check the brittleness of the silver coating. The experimental results are graded from 0 to 1.

Claims (7)

1. an iminodisuccinic acid cyanide-free silver plating process additive, is characterized in that, comprises following component: a. iminodisuccinic acid co-complexing agent, including silver ion effective complexing composition, ammonium sulfate, potassium hydroxide, potassium carbonate, solvent is water; the percentage of the quality of silver ion effective complexing composition and the total mass of solution is 50 ~60%; the percentage of the mass of ammonium sulfate to the total mass of the solution is 5 ~ 10%; the percentage of the mass of potassium hydroxide to the total mass of the solution is 5 ~ 10%; the percentage of the mass of potassium carbonate to the total mass of the solution is 5 ~ 10%, the solvent is the mass balance of the solution; b. Combination of brighteners, including polyethylene glycol 6000, iminodisuccinic acid-citric acid copolymer, alkyl glycoside, solvent is water; the percentage of the mass of polyethylene glycol 6000 and the total mass of the solution is 5~10% ; The quality of iminodisuccinic acid-citric acid copolymer and the percentage of total solution mass are 60～70%; The quality of alkyl glucoside and the percentage of solution total mass are 20～35%, and solvent is the solution mass balance; The preparation method of aminodisuccinic acid-citric acid copolymer: Weigh 50g iminodisuccinic acid, 10g citric acid, 20ml water in a container, heat to 80~100℃ in a water bath, react for 10min, then add pH=11 The ammoniacal aqueous solution is fixed to 500ml; The silver ion effective complexing component refers to the reagent that can convert the silver ion in the plating solution into an iminodisuccinic acid co-complexing agent silver ion effective complexing component to form a composite silver ion with a molar ratio of 1:1; The effective complexation of silver ions is divided into one or a combination of nicotinic acid and nicotinamide. 2. iminodisuccinic acid cyanide-free silver plating process additive according to claim 1, is characterized in that, the pH of iminodisuccinic acid co-complexing agent is 8.5～10. 3. iminodisuccinic acid cyanide-free silver plating process additive according to claim 2, is characterized in that, the pH of combination brightener is 7.5～10. 4. The iminodisuccinic acid cyanide-free silver plating process additive according to claim 1, characterized in that, nicotinic acid, nicotinamide, and iminodisuccinic acid-citric acid copolymer are all biodegradable materials. 5. according to the using method of iminodisuccinic acid cyanide-free silver-plating process additive described in any one of claim 1-4, it is characterized in that, iminodisuccinic acid is added to alkaline solution and stirred until fully dissolved, and the pH is adjusted to Alkaline; add silver salt solution dissolved in water, and stir until the solution is completely uniform; add combined brightener and buffer, and stir until completely dissolved; add water to volume, and adjust pH. 6. the using method of iminodisuccinic acid cyanide-free silver plating process additive according to claim 5, is characterized in that, described silver salt solution is silver nitrate or silver methanesulfonate solution. 7. the using method of iminodisuccinic acid cyanide-free silver-plating process additive according to claim 5, is characterized in that, described buffering agent is wherein one of carbonate, citrate, methanesulfonate or Several kinds.