Low-foam acidic zinc plating additive and preparation process thereof

Abstract

The invention discloses a low-foam acidic zinc plating additive and a preparation process thereof, and belongs to the technical field of electroplating additives, the additive comprises a low-foam softening agent and a water-based brightener, and the low-foam softening agent comprises the following raw materials in percentage by mass: 0.8-1.2% of polyethyleneimine, 0.03-0.06% of monododecyl phosphate potassium, 0.2-0.6% of water-soluble polyether amine and the balance of water. The water-based brightener is prepared from the following raw materials: 0.6 to 1.2 percent of 5-hydroxymethylfurfural, 0.2 to 0.4 percent of L-cysteine salt, 0.1 to 0.15 percent of 4-amino-2 (1H) pyrimidone, 0.05 to 0.1 percent of sodium salicylate, 1 to 1.5 percent of citric acid, 0.3 to 0.5 percent of alpha-ketoglutaric acid, 0.2 to 0.4 percent of erythorbic acid and the balance of water. The water-based formula is prepared by optimizing the components in the additive, the components are uniformly dispersed, the foam amount is low, and the plating quality is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electroplating additives, and particularly relates to a low-foam acid zinc plating additive and a preparation process thereof. BACKGROUND

[0002] Zinc plating is an important part of metal surface treatment technology and is widely used in various fields such as automobiles, construction, electronics, aerospace, etc. Although the traditional zinc plating process meets the industrial demand to some extent, its limitations are increasingly prominent with the rapid development of manufacturing industry and the increasingly stringent environmental protection requirements. The traditional zinc plating process often has problems such as unstable plating layer quality, low electroplating efficiency, and serious environmental pollution, which is difficult to meet the demand of modern industry for efficient, environmentally friendly, and high-quality zinc plating layer.

[0003] High-performance acid zinc plating technology, as a new type of zinc plating process, has become an important way to solve the problems of traditional zinc plating process due to its high plating speed, high brightness, excellent ductility, and environmental protection. However, the research and application of high-performance acid zinc plating technology still face many challenges, such as optimization of additive formula, precise control of process parameters, and improvement of environmental performance.

[0004] Traditional acid zinc plating additives are mostly oily formulations, which cause serious pollution to the environment and harm the health of operators and the ecological environment during production, use, and disposal. In addition, in the prior art, the acid zinc plating additive has the problems of excessive foam and unstable plating solution during use, resulting in poor brightness and leveling quality of the plating layer surface. SUMMARY

[0005] The application provides a low-foam acid zinc plating additive and a preparation process thereof, which can solve the problem of excessive foam of the acid zinc plating additive in the prior art.

[0006] The object of the application can be achieved by the following technical solutions: A low-foam acid zinc plating additive, the additive comprising a low-foam softener and a water-based brightener; The low-foam softener comprises the following raw materials in terms of mass percentage: Polyethyleneimine 0.8-1.2%, potassium monododecyl phosphate 0.03-0.06%, water-soluble polyetheramine 0.2-0.6%, and the balance being water.

[0007] The water-based brightener comprises the following raw materials: 5-Hydroxymethylfurfural 0.6-1.2%, L-cysteine salt 0.2-0.4%, 4-amino-2(1H)pyrimidinone 0.1-0.15%, sodium salicylate 0.05-0.1%, citric acid 1-1.5%, alpha-ketoglutaric acid 0.3-0.5%, isoascorbic acid 0.2-0.4%, and the balance being water.

[0008] In the low-foam softener, polyethylene imine as a cationic polymer is adsorbed on the cathode surface to form a directional arrangement, refine the grain, and the flexibility of the polymer chain can buffer the internal stress of the coating layer, reduce brittleness, and enhance the ductility of the coating layer. Potassium monododecyl phosphate has the properties of wetting, dispersion and low foaming, and can promote H2 escape while reducing surface tension, and eliminate pores on the surface of the plated part. Water-soluble polyether amine provides steric hindrance effect to inhibit the generation of foam, has excellent foam inhibition and dispersion stability, and enhances the plating solution coverage. Potassium monododecyl phosphate and potassium monododecyl phosphate can achieve long-acting low foam.

[0009] The components in the water-based brightener have water solubility and can be uniformly dispersed in the plating solution. 5-hydroxymethyl furfural has better water solubility than traditional o-chlorobenzaldehyde and benzoin ethyl ether, and its raw material is derived from biomass, which can reduce the dependence on petroleum resources. As an aldehyde brightener, the furan ring has high reactivity, and its five-membered ring structure and the presence of oxygen atoms make it more likely to react in an acidic environment, enhancing cathode polarization, promoting the ordered deposition of zinc ions, and improving the gloss of the coating. L-cysteine salt is a sulfur-containing amino acid that is adsorbed on the growth site through the -SH group to inhibit rapid deposition and refine the grain. 4-amino-2(1H) pyrimidinone is a heterocyclic ketone compound, and the pyrimidinone ring is adsorbed on the cathode protrusion site through π electrons to inhibit rapid deposition of zinc ions and achieve micro-leveling. It can improve the brightness and leveling of 5-hydroxymethyl furfural. 4-amino-2(1H) pyrimidinone forms a sulfur-nitrogen synergistic adsorption layer with L-cysteine salt to improve the leveling degree. Sodium salicylate and citric acid as a complex complexing buffer system can stabilize the concentration of zinc ions, prevent rapid deposition, and inhibit local pH rise. Alpha-ketoglutaric acid can improve the coverage of low areas, and erythorbic acid can prevent the darkening of the coating caused by the oxidation of metal ions (such as Fe 2+ ).

[0010] When the low-foam softener and the water-based brightener are used together, the long-chain skeleton of polyethylene imine and the -SH group of L-cysteine and the amino group of pyrimidinone form a three-dimensional network adsorption layer, which increases the deposition energy barrier of zinc ions and realizes ultra-fine grain. The sodium salicylate and citric acid in the brightener form an ion-hydrogen bond double network with polyethylene imine to control the deposition rate of zinc ions. The -SH bond of L-cysteine salt bonds with carbon impurities on the cast iron surface to achieve micro-pore closure and improve the density of the coating.

[0011] Further, the pH of the low-foam softener is 7-9, and the pH of the water-based brightener is 3.3-3.5. The low-foam softener and the water-based brightener are divided into two parts of additives, and the pH is distinguished to prevent premature failure of different components and improve the effect.

[0012] Further, the volume ratio of the low-foam softener and the water-based brightener in the additive is (30-40):(1-3).

[0013] Further, the molecular weight of the polyethylene imine is 10000-50000 Da.

[0014] Further, the water-soluble polyether amine is polyether amine D230 and polyether amine D400.

[0015] Further, the L-cysteine salt is L-cysteine hydrochloride monohydrate.

[0016] Further, the mass ratio of the potassium monododecyl phosphate and the water-soluble polyether amine is 1:8-10. The potassium monododecyl phosphate can reduce the surface tension of the plating solution, form a thinner liquid film, and the long chain of the polyether amine is inserted into the foam liquid film to destroy the elasticity of the film, thereby achieving self-defoaming.

[0017] Further, the mass ratio of the 5-hydroxymethylfurfural, the L-cysteine salt and the 4-amino-2(1H) pyrimidinone is 1:(0.3-0.4):(0.1-0.2). The L-cysteine salt is preferentially adsorbed on the high active site to inhibit the excessive growth of zinc, the 5-hydroxymethylfurfural enhances the cathode polarization to promote the ordered deposition of zinc ions, the 4-amino-2(1H) pyrimidinone is stacked on the surface of the adsorption layer in a planar ring structure to inhibit the formation of coarse crystals, and there is a dynamic synergistic effect among the three to control the deposition rate of zinc ions and improve the gloss.

[0018] Further, the mass ratio of the alpha-ketoglutaric acid and the isoascorbic acid is 1.2-1.5:1.

[0019] The application also provides a preparation process of the low-foam acid zinc plating additive. Step one, preparing the low-foam softener: adding polyethylene imine into deionized water, stirring and dissolving, adding water-soluble polyether amine, stirring and dissolving at a temperature of 30-40 DEG C, and adding potassium monododecyl phosphate in the form of spray and stirring and mixing uniformly to form the low-foam softener.

[0020] Step two, preparing the water-based brightener: adding citric acid and alpha-ketoglutaric acid into deionized water, stirring and dissolving, adding sodium salicylate, ultrasonic dissolving, adding L-cysteine salt and 4-amino-2(1H) pyrimidinone, mixing, adding 5-hydroxymethylfurfural and isoascorbic acid under light-proof conditions, stirring and dissolving to obtain the water-based brightener.

[0021] The application has the following beneficial effects: (1) The water-based formula is prepared by optimizing the components in the additive, compared with the traditional oil-phase formula, no organic solvent is needed, the components have good solubility in water, can be uniformly dispersed, the amount of active agent is reduced, the amount of foam in the zinc plating stirring is reduced, and the compactness of the plating layer is improved.

[0022] (2) The additive of the present application is composed of a neutral and slightly alkaline low-foam softener and an acidic water-based brightener, wherein different types of active agents are selected in the low-foam softener, the polyethyleneimine with high molecular chain is used to improve the ductility and flexibility of the plating layer, and the potassium monododecyl phosphate and the water-soluble polyetheramine are matched to improve the wettability while having the self-foam characteristics, so that a large amount of bubbles will not be generated even under air stirring and connection of the filtering device, and the process applicability is improved.

[0023] (3) The brightener of the present application combines the synergistic effect of 5-hydroxymethyl furfural, L-cysteine salt and 4-amino-2(1H) pyrimidinone to improve the brightness of the plating layer, control the deposition rate of zinc ions, and help to obtain a bright, flat and ductile zinc plating layer with compact crystal and excellent corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0024] The present application will be further described below in conjunction with the drawings.

[0025] Figure 1 is the air stirring effect diagram of the bath solution prepared by the additive of Example 1 of the present application; Figure 2 is the air stirring effect diagram of the bath solution prepared by the additive of Comparative Example 6 of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Example 1 A low-foam acidic zinc plating additive, the additive comprises a low-foam softener and a water-based brightener; The low-foam softener comprises the following raw materials in mass percentage: polyethyleneimine (molecular weight 10000-50000 Da) 1.0%, potassium monododecyl phosphate 0.05%, polyetheramine D230 0.4%, and the balance is water; The water-based brightener comprises the following raw materials: 5-hydroxymethylfurfural 1.0%, L-cysteine hydrochloride monohydrate 0.3%, 4-amino-2(1H)pyrimidinone 0.12%, sodium salicylate 0.08%, citric acid 1.2%, alpha-ketoglutaric acid 0.4%, erythorbic acid 0.3%, and the balance being water.

[0028] The preparation process of the additive is as follows: Step one, preparation of low-foaming softener: polyethyleneimine is added to deionized water, stirred and dissolved, polyetheramine D230 is added, the temperature is raised to 35°C, stirred and dissolved, potassium monododecyl phosphate is added in the form of spray, stirred and mixed uniformly to form a low-foaming softener, and the pH is 7-9.

[0029] Step two, preparation of water-based brightener: citric acid and alpha-ketoglutaric acid are added to deionized water, stirred and dissolved, sodium salicylate is added, ultrasonically dissolved, L-cysteine hydrochloride monohydrate and 4-amino-2(1H)pyrimidinone are added, mixed, 5-hydroxymethylfurfural and erythorbic acid are added under light-proof conditions, stirred and dissolved to obtain a water-based brightener, and the pH is 3.3-3.5.

[0030] Example 2-3 The difference from Example 1 is only that the proportion of polyethyleneimine in the low-foaming softener is different, and the other steps and conditions are the same as those in Example 1. The specific proportions are shown in Table 1.

[0031] Table 1 Example 4-5 The difference from Example 1 is only that the proportion of potassium monododecyl phosphate and polyetheramine D230 in the low-foaming softener is different, and the other steps and conditions are the same as those in Example 1. The specific proportions are shown in Table 2.

[0032] Table 2 Example 6-7 The difference from Example 1 is only that the proportion of raw materials in the water-based brightener is different, and the other steps and conditions are the same as those in Example 1. The specific proportions are shown in Table 3.

[0033] Table 3 Comparative Example 1 The difference from Example 1 is only that o-chlorobenzaldehyde is used instead of 5-hydroxymethylfurfural in this comparative example. The other conditions and steps are the same as those in Example 1.

[0034] Comparative Example 2 The difference from Example 1 is only that benzylidene acetone is used instead of 4-amino-2(1H)pyrimidinone in this comparative example. The other conditions and steps are the same as those in Example 1.

[0035] Comparative Example 3 The difference between Example 1 and this comparative example is that o-chlorobenzene formaldehyde is used instead of 5-hydroxymethyl furfural and benzyl propyl ketone is used instead of 4-amino-2(1H) pyrimidinone. Other conditions and steps are the same as Example 1.

[0036] Comparative Example 4 The difference between Example 1 and this comparative example is that L-cysteine hydrochloride monohydrate is not added. Other conditions and steps are the same as Example 1.

[0037] Comparative Example 5 The difference between Example 1 and this comparative example is that potassium monododecyl phosphate is not added in the low-foaming softener. Other conditions and steps are the same as Example 1.

[0038] Comparative Example 6 The difference between Example 1 and this comparative example is that polyether amine D230 is not added in the low-foaming softener. Other conditions and steps are the same as Example 1.

[0039] The additives prepared in the above examples and comparative examples are added to the acid zinc plating solution for hanging plating and barrel plating to form a bath, as shown in Table 4: Table 4 The carbon steel parts are plated with the above bath, and the test results are shown in Table 5.

[0040] Table 5 The barrel plating bath of Example 1-7, Comparative Example 5 and Comparative Example 6 is subjected to a foam test. 50 mL of the bath is injected into a 250 mL graduated cylinder with a stopper, and the shaking and foaming method is tested by shaking 50 times up and down. The foam volume of 11 groups of baths after standing for 0 min, 2 min, 4 min and 6 min after foaming is recorded, and the results are shown in Table 6.

[0041] Table 6 As can be seen from Table 5, the additives prepared in the examples and the comparative examples are added to the acidic galvanizing electroplating solution to adjust the performance of the plating solution. As the main softening agent, the polyethyleneimine is added in reduced amount in Example 2, and the dispersion capacity of the plating solution is reduced. In Example 3, the amount of polyethyleneimine is increased compared with Example 1, and due to the properties of the high molecular polymer, the viscosity of the bath solution is increased, which is not conducive to zinc plating. In Example 4 and Example 5, the ratio of potassium monododecyl phosphate and polyetheramine in the softening agent is adjusted based on Example 1. Compared with the ratio in Example 1, the ratio in Example 1 is optimal, and the effect is the best. In Example 1, Example 5 and Example 6, the ratio of the water-based brightener is slightly adjusted, and the bath solution detection results of Example 6 and Example 7 are not as good as those of Example 1. In combination of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, the effect of the present application is better than that of the main brightener component used in the traditional additives. As can be seen from the amount of foam in Example 1, Comparative Example 4 and Comparative Example 5, the use of potassium monododecyl phosphate and water-soluble polyetheramine in the softening agent can achieve the effect of suppressing and eliminating foam, as shown in Figure 1 The effect of air stirring of the bath solution of Example 1 in the Hull cell is shown in Figure 2 The air stirring effect of the bath solution of Comparative Example 6 is shown in

[0042] It should be noted that the relational terms herein such as first and second, and the like are used merely to distinguish one entity or action from another entity or action, without necessarily requiring or implying that there is any such actual relationship or order between such entities or actions. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0043] Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, alternatives, and variations can be made thereto without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A low-foaming acidic zinc plating additive, characterized in that, The additives include low-foaming softeners and water-based brighteners; The low-foaming softener comprises the following raw materials by weight percentage: Polyethyleneimine 0.8-1.2%, potassium monododecyl phosphate 0.03-0.06%, water-soluble polyetheramine 0.2-0.6%, balance being water; The water-based brightener comprises the following raw materials: 5-Hydroxymethylfurfural 0.6-1.2%, L-cysteine ​​0.2-0.4%, 4-amino-2(1H)pyrimidinone 0.1-0.15%, sodium salicylate 0.05-0.1%, citric acid 1-1.5%, α-ketoglutarate 0.3-0.5%, isoascorbic acid 0.2-0.4%, balance being water.

2. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The low-foaming softener has a pH of 7-9; the water-based brightener has a pH of 3.3-3.

5.

3. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The volume ratio of the low-foaming softener and the water-based brightener used in the additive is (30-40):(1-3).

4. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The molecular weight of the polyethyleneimine is 10,000-50,000 Da.

5. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The water-soluble polyetheramines are polyetheramine D230 and polyetheramine D400.

6. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The L-cysteine ​​salt is L-cysteine ​​hydrochloride monohydrate.

7. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The mass ratio of potassium monododecyl phosphate to water-soluble polyetheramine is 1:8-10.

8. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The mass ratio of 5-hydroxymethylfurfural, L-cysteine ​​salt and 4-amino-2(1H)pyrimidinone is 1:(0.3-0.4):(0.1-0.2).

9. The low-foaming acidic zinc plating additive according to claim 1, characterized in that, The mass ratio of α-ketoglutarate to isoascorbic acid is 1.2-1.5:

1.

10. A preparation process for a low-foaming acidic zinc plating additive as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Prepare low-foaming softener: Add polyethyleneimine to deionized water and stir to dissolve. Add water-soluble polyetheramine, heat to 30-40℃ and stir to dissolve. Add potassium monododecyl phosphate in spray form and stir to mix evenly to form low-foaming softener. Step 2: Preparation of water-based brightener: Add citric acid and α-ketoglutaric acid to deionized water, stir to dissolve, then add sodium salicylate, sonicate to dissolve, then add L-cysteine ​​salt and 4-amino-2(1H)pyrimidinone, mix, then add 5-hydroxymethylfurfural and isoascorbic acid under light-protected conditions, stir to dissolve, and obtain water-based brightener.

Images