CN115304945B - Environment-friendly gold-plating protection liquid and preparation method thereof - Google Patents

Abstract

The application relates to the field of surface treatment, in particular to an environment-friendly gold-plating protective solution and a preparation method thereof. The composite material comprises the following raw materials in parts by weight: 980-1020 parts of water, 200-240 parts of emulsifying dispersant, 3-5 parts of azole organic matters, 3-5 parts of imidazole organic matters and 25-35 parts of mercapto long-chain organic matters; the mercapto long-chain organic matter is dodecyl mercaptan and/or hexadecyl mercaptan; the application has synergistic effect by compounding mercapto long-chain organic matters, azole organic matters and imidazole organic matters, so that the obtained gold-plating protective liquid is used for gold-plating products, can be self-assembled into a compact protective film on the surfaces of the gold-plating products, reduces the contact between the surfaces of the gold-plating products and air, improves the color-proof effect of the gold-plating products, and simultaneously has the advantages that the raw materials are non-toxic or nearly non-toxic substances, and the environmental protection of the protective liquid is improved.

Description

Environment-friendly gold-plating protection liquid and preparation method thereof

Technical Field

The application relates to the field of surface treatment, in particular to an environment-friendly gold-plating protective solution and a preparation method thereof.

Background

Gold plating is a decoration process, and is characterized in that a gold layer, silver layer, copper layer and the like are coated on the surface of an ornament, and because the gold plating product layer is contacted with air for a long time, phenomena such as oxygen and color change are easy to occur, therefore, white surface treatment and the like are generally adopted for treatment, so that a protective film is formed on the surface of the gold plating product layer, and common surface treatment comprises chemical passivation, electroplating and chemical film, wherein the chemical passivation is easy to produce heavy metal pollution such as nickel, chromium and the like, the electroplating process is complex, the chemical film is difficult to control, and the self-assembly mode is proposed to form the protective film.

The self-assembly process is not a simple superposition of weak acting forces among a large number of atoms, ions and molecules, but a plurality of bodies are spontaneously associated and gathered together to form a compact and orderly whole, and the self-assembly process is a complex synergistic effect of the whole. Molecular self-assembly is research on molecular self-assembly by utilizing LB film, and is an important research content of molecular engineering. For example, functional macromolecules are embedded into the surface of LB film by using biological affinity or bonding force between groups with the aid of a pen point of a Scanning Tunneling Microscope (STM), and immobilized by photopolymerization to form a functional film. The self-assembled protective film not only can protect gold-plated products, but also has the advantages of no environmental pollution, simple operation and the like.

However, the existing protective film formed by self-assembly has the phenomena of easy discoloration, darkening, easy abrasion and the like, so that the surface of the gold-plated product is easy to be discolored, and the attractiveness of the gold-plated product is affected.

Disclosure of Invention

In order to reduce the possibility of color change of gold-plated products, the application provides an environment-friendly gold-plated protection solution and a preparation method thereof.

In a first aspect, the application provides an environment-friendly gold-plating protective solution, which comprises the following raw materials in parts by weight:

980-1020 parts of water

200-240 parts of emulsifying dispersant

3-5 parts of azole organic matters

3-5 parts of imidazole organic matters

25-35 parts of sulfhydryl long-chain organic substances;

the mercapto long-chain organic matter is dodecyl mercaptan and/or hexadecyl mercaptan.

The raw materials and the weight parts of the raw materials are the preferred proposal of the application, and the mercapto long-chain organic matter is added, so that the mercapto long-chain organic matter can self-assemble on the surface of the gold-plated product to form a layer of nano-scale protective film, thereby isolating the surface of the gold-plated workpiece from being in direct contact with water vapor or oxide in the air, further achieving the anti-discoloration effect, and the film does not change the weldability, contact resistance and other functional characteristics of the gold-plated layer. The addition of the azole organic matters and the imidazole organic matters all play a synergistic effect with the mercapto long-chain organic matters, so that the obtained gold-plating protective solution is used for gold-plating products, is self-assembled into a compact protective film, further improves the anti-discoloration effect of the gold-plating products, and the emulsifying and dispersing agent has an emulsifying and dispersing effect, and the water has a diluting effect, so that the obtained protective solution is easy to form a stable protective film on the surface of the metal products, so that the gold-plating products are better protected, the possibility of discoloration of the gold-plating products is reduced, and the gold-plating products are attractive. The adopted raw materials are uniform and environment-friendly neutral raw materials, so that the environment is not easily influenced, and the environment friendliness of the gold-plating protective solution is improved.

Further, by adding dodecyl mercaptan and/or hexadecyl mercaptan, the dodecyl mercaptan and the hexadecyl mercaptan can be used as nonionic surfactants, organic synthesizers, bactericides, rust inhibitors and the like, when the prepared protective liquid is used for gold-plated products, a protective film can be formed on the surface of the gold-plated products in a self-assembly mode, and the protective film can reduce the air from entering into contact with the surface of the gold-plated products, reduce the possibility of color change of the gold-plated products and enable the gold-plated products to be attractive.

Preferably, the azole organic compound is benzotriazole.

The BTA can be used as a corrosion inhibitor and a metal antirust agent, and the BTA and metal atoms form covalent bonds and coordination bonds to replace each other to form chain polymers, and a multi-layer protective film is formed on the surface of the metal, so that the surface of the metal does not have oxidation-reduction reaction, does not generate hydrogen, has an anticorrosion effect, reduces the possibility of color change of the metal, can be used as an ultraviolet light absorber, and has a stabilizing effect on ultraviolet light sensitive products; therefore, by adding BTA, the obtained protective liquid is used for gold-plated products, a stable protective film can be formed on the gold-plated surfaces, the color change prevention effect is achieved, and the outer surfaces of the gold-plated products are attractive.

Preferably, the imidazole organic matter is 2-mercaptobenzimidazole.

The 2-mercaptobenzimidazole is simply called MB, is used as a brightening agent, can improve the gloss of the surface of a gold-plated product, and simultaneously plays a synergistic anti-aging and discoloration-resistant role with benzotriazole and mercapto long-chain organic matters, so that the phenomenon of discoloration on the surface of the gold-plated product is reduced. In addition, MB is a nontoxic raw material, and cannot influence the environment, so that the environmental protection of the protective solution is improved.

Preferably, the emulsifying dispersant is one or more of OP-10, AEO-9 and PEG.

The OP-10 has good emulsifying property, diffusivity, antistatic property and wettability, can uniformly disperse a raw material system of the protective liquid, and can ensure that the protective liquid has wettability, and when the OP-10 is used for treating a gold-plated product, the surface of the gold-plated product can be rapidly lubricated, so that a protective film is easily formed on the surface of the gold-plated product. In addition, the AEO-9 and the PEG can both enhance the dispersibility and the wettability of the protective liquid, and when the OP-10, the AEO-9 and the PEG are compounded, the wettability and the dispersibility of the protective liquid can be improved, so that when the protective liquid is used for a gold-plated product, a uniform and stable protective film is formed on the surface of the gold-plated product, the protective film has a better antirust effect on the gold-plated product, and the possibility of color change of the gold-plated product is reduced.

Wherein the molecular weight of PEG is 400-600, the HLB value of OP-10 is 14.5-17.5, and the HLB value of AEO-9 is 13.5-14.5.

Preferably, the adhesive also comprises 4-7 parts by weight of a complexing agent, wherein the complexing agent comprises the following raw materials in parts by weight:

15-25 parts of water

1-3 parts of silicon micropowder

Organosiloxane 4-7 parts

3.2-4.5 parts of PEG derivative

0.001-0.003 parts of ammonium persulfate.

Generally, in life, common gold-plated products are provided with outer box frames of mobile phones, computers, flat plates and the like, and the gold-plated products are inevitably scraped in the use process, so that protective films on the surfaces of the gold-plated products are worn or worn, and when the protective films are worn or worn, water in air easily enters into contact with the surfaces of the gold-plated products, so that the gold-plated products are easy to change color. Meanwhile, mobile phones, computers, flat plates and the like are easy to burn in the use process, so that the protective film is easy to change color, and the attractiveness of the gold-plated product is affected.

Therefore, the complexing agent has better wear resistance, adhesiveness and temperature resistance, and when the obtained protective liquid is used for a gold-plated product, the self-assembled protective film can be stabilized on the gold-plated product, the abrasion of the protective film is reduced, the temperature resistance of the protective film is improved, and the gold-plated product is difficult to change color and is attractive.

Specifically, the complexing agent is composed of raw materials such as silicon micropowder, organosiloxane, PEG derivative and the like, and the raw materials and the weight parts of the raw materials are all in a preferred range of the application. The particle size of the silicon micro powder is preferably 5-10nm, and the silicon micro powder is added to the gold-plated product, so that the gold-plated product has the advantages of good temperature resistance, acid and alkali corrosion resistance, stable chemical property, high hardness and the like, has the excellent properties of fracture resistance, impermeability, corrosion resistance, impact resistance, wear resistance and the like, is further used for protecting liquid, can enable a protecting film formed by the protecting liquid to have the properties of good wear resistance, corrosion resistance, temperature resistance and the like, reduces abrasion or break of the protecting film of the gold-plated product in the use process, and further reduces the contact of water and oxygen in the air with the surface of the gold-plated product, thereby reducing the possibility of color change of the surface of the gold-plated product and enabling the gold-plated product to be attractive.

In addition, the silica micropowder is a nontoxic and environment-friendly inorganic filler, so that the environment-friendly property of the protective solution is improved.

The organic siloxane has better coupling effect, can improve the compatibility of the silica powder and the polymer, can also improve the stability of a protective film formed by the protective solution on a gold-plated product, and can also improve the temperature resistance of the protective film and reduce the possibility of color change. The PEG derivative has good film forming property and dispersibility, so that the protective liquid can easily form a film on the surface of the gold-plated product, and can be easily dispersed, so that the surface of the gold-plated product forms a uniform protective film, and the gold-plated product can be better protected. And under the initiation of ammonium persulfate, the organic siloxane and the PEG derivative are compounded to form a macromolecular compound, when the protective solution is used for a gold-plated product, a stable protective film can be formed on the surface of the gold-plated product, and the film has better temperature resistance, wear resistance and discoloration resistance (the discoloration resistance means the possibility of difficult occurrence of discoloration).

Preferably, the organosiloxane consists of methoxy polyoxyethylene propyl trimethoxy silane, phenoxy propyl trimethoxy silane and gamma glycidoxy propyl trimethoxy silane in the weight ratio of (1.2-1.4): 1.5-1.8): 1.

Methoxy polyethylene oxide propyl trimethoxy silane, phenoxy propyl trimethoxy silane and gamma glycidoxy propyl trimethoxy silane can be used as polymerization monomers, and can play a better role in coupling, bonding, high temperature resistance and the like, so that the prepared protective solution has better high temperature resistance, discoloration resistance (possibility of difficult occurrence of discoloration), wear resistance and the like when used for gold plating products by compounding 1 in parts by weight of 1 to 1.4 of the methoxy polyethylene oxide propyl trimethoxy silane, the phenoxy propyl trimethoxy silane and the gamma glycidoxy propyl trimethoxy silane.

Preferably, the PEG derivative comprises the following components in parts by weight: (2.3-4.8).

The double-end carboxyl polyethylene glycol and the sulfhydryl polyethylene glycol carboxyl are used in a compound way, so that the synergistic effect is achieved, the film forming property and the dispersibility are better, and the molecular weight of the double-end carboxyl polyethylene glycol is 2000. The molecular weight of the sulfhydryl polyethylene glycol carboxyl is 3400-5000, and the thiol group has high affinity to the gold surface, and is widely used for gold nanoparticle or gold film modification. The carboxyl group (-COOH) can easily form a stable amide bond with the amino group, and can also form an ester bond with the hydroxyl group. When the weight ratio of the carboxyl groups of the double-end carboxyl polyethylene glycol and the sulfhydryl polyethylene glycol is 1: and (2.3-4.8) can be compounded with the organosiloxane to obtain a macromolecular compound when the macromolecular compound solution is used for a gold-plated product, and meanwhile, a protective film with good stability, color change resistance, good wear resistance and good temperature resistance is formed, so that the contact between the gold-plated product and air is reduced, the possibility of color change of the gold-plated product is reduced, and the gold-plated product is attractive.

Preferably, the complexing agent is prepared by the following method:

step 1: weighing and mixing the organic siloxane and water according to parts by weight, hydrolyzing for 15-30min to obtain a hydrolysate, and then weighing and uniformly mixing the silicon micropowder and the hydrolysate to obtain a mixture;

step 2: weighing the PEG derivative according to the weight parts, uniformly mixing the PEG derivative and the mixture, heating to 55-65 ℃, adding ammonia persulfate, reacting for 1-3 hours, heating to 100-105 ℃, and distilling under reduced pressure for 30-45min to obtain the complexing agent.

The preparation method is simple to operate and high in production efficiency, in the step 1, the organic siloxane is fully hydrolyzed by mixing with water, the hydrolyzed solution is mixed with the silicon micro powder (the inophilic groups in the hydrolyzed solution are combined with the silicon micro powder, the organic siloxane is excessive in dosage, and after part of inophilic groups are combined with the silicon micro powder, the rest inophilic groups are stably adhered to the surface of a gold-plated product during self-assembly film forming), so that a mixture is obtained; and (2) compounding the PEG derivative in the step (2) with a mixture under the action of ammonium persulfate, and then carrying out reduced pressure distillation to obtain a complexing agent. The composite agent is added with raw materials such as silicon micropowder, organic siloxane, PEG derivative and the like, so that when the prepared protective solution is used for gold-plated products, the formed film has better wear resistance, temperature resistance, discoloration resistance and the like, and the gold-plated products are likely to be discolored.

In a second aspect, the application provides a preparation method of an environment-friendly gold-plating protective solution, which adopts the following technical scheme: weighing the emulsifying dispersant according to parts by weight, heating to 50-80 ℃, adding the azole organic matters, the imidazole organic matters and the mercapto long-chain organic matters, and stirring uniformly while adding water to obtain the protection liquid.

The preparation method has the advantages of simple operation and high production efficiency, and the prepared protective liquid is used for forming the protective film of the gold-plated product, has a good anti-discoloration effect, and needs to be diluted with water by 1:10 when being used for the gold-plated product.

Preferably, the protective liquid is prepared by adding water into the complexing agent, and stirring uniformly the complexing agent, the azole organic matter, the imidazole organic matter and the mercapto long-chain organic matter.

The protective liquid prepared by the method can reduce the phenomena of color change, abrasion and the like on the surface of a gold-plated product when being used for the gold-plated product. The produced protective film has wear resistance, temperature resistance, discoloration resistance and the like, and further reduces the possibility of discoloration of gold-plated products.

In summary, the application has the following beneficial effects:

1. the application has synergistic effect by compounding mercapto long-chain organic matters, azole organic matters and imidazole organic matters, so that the obtained gold-plating protective liquid is used for gold-plating products, can self-assemble a compact protective film on the surfaces of the gold-plating products, reduces the contact between the surfaces of the gold-plating products and air, improves the color-proof effect of the gold-plating products, and meanwhile, the adopted raw materials are uniform and environment-friendly neutral raw materials, thereby being not easy to influence the environment and improving the environmental protection of the gold-plating protective liquid. Further, the mercapto long-chain organic matter is dodecyl mercaptan and/or hexadecyl mercaptan; the dodecyl mercaptan and the hexadecyl mercaptan can form a protective film on the surface of the gold-plated product, so that air is reduced from entering into contact with the surface of the gold-plated product, and the possibility of color change of the gold-plated product is reduced.

2. The complexing agent prepared from the raw materials such as the silicon micropowder, the organic siloxane and the PEG derivative can enable the protective film formed by the protective solution to have better performances such as wear resistance, corrosion resistance, temperature resistance and the like, reduce abrasion or abrasion of the protective film of the gold-plated product in the use process, further reduce the entry of water and oxygen in the air into contact with the surface of the gold-plated product, and further reduce the possibility of color change on the surface of the gold-plated product.

3. By compounding methoxy polyethylene oxide propyl trimethoxy silane, phenoxy propyl trimethoxy silane and gamma glycidoxy propyl trimethoxy silane, the compatibility of silicon micropowder and polymer can be improved, so that the prepared protective solution forms a stable protective film on the surface of a gold-plated product, and the film has better temperature resistance, wear resistance and discoloration resistance, and the possibility of discoloration of the gold-plated product is reduced.

Detailed Description

The present application will be described in further detail with reference to examples.

Examples

Example 1

An environment-friendly gold-plating protective solution comprises the following preparation methods:

2000g OP-10 is weighed and heated to 60 ℃, 30g benzotriazole, 30g 2-mercaptobenzimidazole and 250g dodecyl mercaptan are added, 9800g water is added, and the mixture is stirred uniformly to obtain a protection solution.

Examples 2 to 3

Examples 2-3 differ from example 1 in that: the amounts of the raw materials used are different, and are shown in Table 1;

TABLE 1 raw materials used in examples 1-3 (g)

Example 4

Example 4 differs from example 1 in that: the environment-friendly gold-plating protective solution is prepared by weighing 2000g of OP-10, heating to 60 ℃, adding 30g of benzotriazole, 30g of 2-mercaptobenzimidazole, 250g of dodecyl mercaptan and 4kg of complexing agent, and stirring uniformly while adding 9800g of water.

Wherein the complexing agent is prepared by the following method:

step 1: 1.3kg of methoxy polyethylene oxide propyl trimethoxy silane, 1.62kg of phenoxy propyl trimethoxy silane, 1.08kg of gamma glycidoxypropyl trimethoxy silane and 15kg of water are weighed and mixed, and are stirred and hydrolyzed for 15min to obtain a hydrolysate, and then 1kg of silicon micropowder and all the obtained hydrolysates are weighed and uniformly mixed to obtain a mixture.

Step 2: weighing 0.97kg of double-end carboxyl polyethylene glycol and 2.23kg of sulfhydryl polyethylene glycol carboxyl, putting the double-end carboxyl polyethylene glycol and the 2.23kg of sulfhydryl polyethylene glycol carboxyl into a reaction kettle together with all the mixture obtained in the step 1, sealing and uniformly mixing, heating to 55 ℃, adding 0.001kg of ammonium persulfate, reacting for 1h, heating to 100 ℃, starting reduced pressure distillation for 30min, and completely evaporating water to obtain the complexing agent.

Examples 5 to 6

Examples 5-6 differ from example 4 in that: the amounts of the raw materials used are different, and are shown in Table 2;

TABLE 2 raw materials used (kg) for examples 4 to 6

Comparative example

Comparative example 1

Comparative example 1 differs from example 1 in that: the imidazole organic matter is replaced by mercapto long-chain organic matter in equivalent.

Comparative example 2

Comparative example 2 is different from example 1 in that: the imidazole organic matter is replaced by mercapto long-chain organic matter in equivalent.

Comparative example 3

Comparative example 3 differs from example 4 in that: the silicon micropowder is replaced by talcum powder in equal quantity.

Comparative example 4

Comparative example 4 differs from example 4 in that: the double-end carboxyl polyethylene glycol is replaced by sulfhydryl polyethylene glycol carboxyl in an equivalent way.

Comparative example 5

Comparative example 5 differs from example 4 in that: the gamma glycidoxypropyl trimethoxysilane is replaced by phenoxypropyl trimethoxysilane in equal amount.

Performance test

The protective liquid prepared in examples 1-6 and comparative examples 1-5 was exchanged with water at a ratio of 1:10 to obtain a working liquid, the gold-plated product was put into the working liquid, immersed for 30 minutes, then the workpiece was taken out, rinsed with clear water, air-dried, and then put into an oven at 50 ℃ for drying for 30 minutes to obtain a gold-plated product, and the following performance test was performed.

Detection method/test method

1) Salt fog performance

Taking a gold-plated product which is not treated by the protective liquid as a blank control group, and then putting the blank control group and the gold-plated product obtained after the treatment by the protective liquid prepared in the examples 1-6 and the comparative examples 1-5 into a salt spray tester together for detecting the performance of the gold-plated product, wherein the test temperature of the salt spray tester is 37 ℃, and the solution in the salt spray tester is sodium chloride solution with the mass fraction of 5%; the sample is placed at an inclination of 45 degrees, and is observed in each two hours, when the sample is observed, the sample is not touched by hands, and the time of occurrence of color change is recorded, wherein the test time of a blank control group is denoted as A0, the rest is denoted as AX, the calculation of the color change resistance rate is performed, the color change resistance rate is = (AX-A0/A0) is 100%, the higher the yellow resistance rate is, the higher the color change resistance rate of the formed protective film is, the color change is not easy to occur, otherwise, the lower the color change resistance rate is, the color change is easy to occur, and specific data are shown in a table 3;

2) Wear resistance

The gold-plated products obtained after the treatment of the protective solutions prepared in examples 1 to 6 and comparative examples 1 to 5 were subjected to abrasion resistance test by an abrasion resistance tester, wherein the friction load was 5N, the friction speed was 43r/min, the friction area was 50 x 150mm, and the number of times of friction was 500. After the test is completed, the test is put into a salt spray tester for detection (the detection condition is the same as 1), the color change time is recorded, and similarly, a gold-plated product which is not treated by the protective liquid is taken as a blank control group and is taken as a control group, and the color change resistance rate is calculated, wherein the test is the same as the color change resistance rate test in the 1), and the specific data are shown in table 3.

3) High temperature resistance test

The gold-plated products obtained after the treatment of the protective liquid prepared in examples 1-6 and comparative examples 1-5 are put into a baking oven at 100 ℃ for 2 hours, taken out, observed whether the surfaces of the gold-plated products have the phenomena of color change and the like, and recorded, wherein specific data are shown in table 3;

TABLE 3 Experimental data for examples 1-6 and comparative examples 1-5

As can be seen from the combination of examples 1-3 and comparative examples 1-2 and the combination of Table 3, the abrasion resistance and the salt fog performance of examples 1-6 are better than those of comparative examples 1-2, and the temperature resistance is also better than that of comparative examples 1-2, which shows that when imidazole organic matters, mercapto long-chain organic matters and imidazole organic matters are used in a compounding manner, the synergistic effect can be better, so that the protective film prepared from the protective solution has better discoloration resistance.

Comparative examples 4 to 6 and comparative examples 3 to 5 show that when the fine silica powder is replaced with talc powder, the discoloration resistance after the abrasion test is reduced, thereby indicating that the abrasion resistance by the fine silica powder is better, and in addition, the discoloration resistance is better when the double-end carboxyl polyethylene glycol and the like and the mercapto polyethylene glycol carboxyl are used in combination. When gamma glycidoxypropyl trimethoxysilane, phenoxypropyl trimethoxysilane and methoxy polyethylene oxide propyl trimethoxysilane are compounded for use, the wear resistance, the discoloration resistance and the like of the protective film prepared by the protective solution are better.

Comparing examples 1-3 with examples 4-6, it can be seen that the salt fog performance and the wear resistance of examples 1-3 are inferior to those of examples 4-6, which shows that the application can effectively improve the wear resistance, discoloration resistance and the like of the formed protective film when the protective liquid is used for gold-plated products by adding the complexing agent, reduce the possibility of discoloration of the gold-plated products, and make the gold-plated products beautiful.

The application is not limited by the explanation, and one skilled in the art can make modifications to the present embodiment without creative contribution as required after reading the present specification, but is protected by patent law as long as it is within the scope of the claims of the present application.

Claims (1)

1. The environment-friendly gold-plating protection solution is characterized by comprising the following raw materials in parts by weight:

980-1020 parts of water

200-240 parts of emulsifying dispersant

3-5 parts of azole organic matters

3-5 parts of imidazole organic matters

25-35 parts of sulfhydryl long-chain organic substance

4-7 parts of complexing agent;

the mercapto long-chain organic matter is dodecyl mercaptan and/or hexadecyl mercaptan;

the azole organic matter is benzotriazole;

the imidazole organic matter is 2-mercaptobenzimidazole;

the emulsifying dispersant is one or more of OP-10, AEO-9 and PEG;

the complexing agent comprises the following raw materials in parts by weight:

15-25 parts of water

1-3 parts of silicon micropowder

Organosiloxane 4-7 parts

3.2-4.5 parts of PEG derivative

0.001-0.003 parts of ammonium persulfate;

the organosiloxane consists of methoxy polyoxyethylene propyl trimethoxy silane, phenoxy propyl trimethoxy silane and gamma glycidoxy propyl trimethoxy silane in the weight ratio of (1.2-1.4) (1.5-1.8) to 1;

the PEG derivative comprises the following components in parts by weight: (2.3-4.8);

the complexing agent is prepared by the following method:

step 1: weighing and mixing the organic siloxane and water according to parts by weight, hydrolyzing for 15-30min to obtain a hydrolysate, and then weighing and uniformly mixing the silicon micropowder and the hydrolysate to obtain a mixture;

step 2: weighing the PEG derivative according to the weight parts, uniformly mixing the PEG derivative and the mixture, heating to 55-65 ℃, adding ammonia persulfate, reacting for 1-3 hours, heating to 100-105 ℃, and distilling under reduced pressure for 30-45min to obtain the complexing agent.