A low-foam acid zinc plating additive and a preparation process thereof

Abstract

The application discloses a low-foam acid zinc plating additive and a preparation process thereof, and belongs to the technical field of electroplating additives. The additive comprises a low-foam softener and a water-based brightener. The low-foam softener comprises the following raw materials in percentage by mass: polyethylene imine 0.8-1.2%, monododecyl phosphate potassium 0.03-0.06%, water-soluble polyether amine 0.2-0.6%, and the balance is water. The water-based brightener comprises the following raw materials: 5-hydroxymethyl furfural 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 is water. The application optimizes the components in the additive, prepares a water-based formula, and the components are uniformly dispersed, the foam amount is low, and the plating layer 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, as an important part of metal surface treatment technology, 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, with the rapid development of manufacturing industry and the increasingly stringent environmental protection requirements, its limitations are increasingly prominent. 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 with 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:

[0007] A low-foam acid zinc plating additive, the additive comprising a low-foam softener and a water-based brightener;

[0008] The low-foam softener comprises the following raw materials in mass percentage:

[0009] Polyethyleneimine 0.8-1.2%, potassium monododecyl phosphate 0.03-0.06%, water-soluble polyetheramine 0.2-0.6%, and the balance being water.

[0010] The water-based brightener comprises the following raw materials:

[0011] 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.

[0012] In the low-foam softener, polyethyleneimine, as a cationic high-molecular polymer, forms directional arrangement on the cathode surface through electrostatic adsorption, refines the crystal grains, and the flexibility of the high-molecular chain buffers the internal stress of the plating layer, reduces the brittleness, and enhances the ductility of the plating layer. Potassium monododecyl phosphate has the properties of wetting, dispersion, and low foaming, reduces the surface tension, promotes the escape of H2, and eliminates the pores on the surface of the plated part. The water-soluble polyether amine provides steric hindrance effect, suppresses the generation of foam, has excellent foam suppression and dispersion stability, and enhances the plating solution coverage. Potassium monododecyl phosphate and the water-soluble polyether amine realize long-acting low foaming in cooperation.

[0013] The components in the water-based brightener have water solubility, can realize uniform dispersion in the plating solution, and 5-hydroxymethylfurfural has better water solubility than traditional o-chlorobenzaldehyde and benzoin ethyl acetal, 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 the five-membered ring structure and the presence of oxygen atoms make it more likely to react in an acidic environment, enhance the cathode polarization, promote the ordered deposition of zinc ions, and improve the gloss of the plating layer. L-cysteine salt is a sulfur-containing amino acid, which is adsorbed on the growth site through the -SH group to inhibit the rapid deposition and refine the crystal grains. 4-amino-2(1H)pyrimidinone is a heterocyclic ketone compound, and the pyrimidinone ring is adsorbed on the cathode protruding part through π electrons to inhibit the rapid deposition of zinc ions, realize microscopic leveling, and improve the brightness and leveling property in cooperation with 5-hydroxymethylfurfural. 4-amino-2(1H)pyrimidinone forms a sulfur-nitrogen synergistic adsorption layer with L-cysteine salt at the same time to improve the leveling degree. Sodium salicylate and citric acid as a composite complex buffer system stabilize the zinc ion concentration, avoid rapid deposition, and inhibit the local pH rise. Alpha-ketoglutaric acid can improve the coverage in the low area, and isoascorbic acid can prevent the darkening of the plating layer caused by the oxidation of metal ions (such as Fe 2+ ).

[0014] When the low-foam softener and the water-based brightener are used in cooperation, the long-chain skeleton of polyethyleneimine and the -SH group of L-cysteine and the amino group of pyrimidinone form a three-dimensional network adsorption layer, which makes the zinc ion deposition energy barrier increase and realizes ultra-fine grain. The sodium salicylate and citric acid in the brightener form an ion bond-hydrogen bond double network with polyethyleneimine to control the zinc ion deposition rate. The -SH bond of L-cysteine salt combines with the carbon impurities on the cast iron surface to realize micro-pore sealing, which can improve the density of the plating layer.

[0015] Further, the pH of the low-foam softener is 7-9; the pH of the aqueous brightener is 3.3-3.5. The low-foam softener and the aqueous brightener are divided into two parts of additives, the pH is distinguished, the premature failure of different components is prevented, and the effect is improved.

[0016] Further, the volume ratio of the low-foam softener and the aqueous brightener used in combination in the additive is (30-40):(1-3).

[0017] Further, the molecular weight of the polyethyleneimine is 10000-50000 Da.

[0018] Further, the water-soluble polyetheramine is polyetheramine D230 and polyetheramine D400.

[0019] Further, the L-cysteine salt is L-cysteine hydrochloride monohydrate.

[0020] Further, the mass ratio of the potassium monododecyl phosphate and the water-soluble polyetheramine 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 polyetheramine inserts into the foam liquid film, destroys the elasticity of the film, and realizes self-defoaming.

[0021] 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, inhibits the excessive growth of zinc, the 5-hydroxymethylfurfural enhances the cathode polarization effect, promotes the ordered deposition of zinc ions, the cathode polarization effect, promotes the ordered deposition of zinc ions, the 4-amino-2(1H) pyrimidinone is stacked on the surface of the adsorption layer in a planar cyclic structure, inhibits the formation of coarse crystals, and there is a dynamic synergistic effect among the three, controls the deposition rate of zinc ions, and improves the gloss.

[0022] Further, the mass ratio of the alpha-ketoglutaric acid and the erythorbic acid is 1.2-1.5:1.

[0023] The application also provides a preparation process of the low-foam acid zinc plating additive.

[0024] Step one, preparing the low-foam softener: adding polyethyleneimine into deionized water, stirring and dissolving, adding water-soluble polyetheramine, stirring and dissolving at a temperature of 30-40℃, adding potassium monododecyl phosphate in the form of spraying, and stirring and mixing uniformly to form the low-foam softener.

[0025] Step two, preparation of water-based brightener: add citric acid and alpha-ketoglutaric acid into deionized water, after stirring and dissolving, add sodium salicylate, ultrasonic dissolution, then add L-cysteine salt and 4-amino-2(1H) pyrimidinone, mix, then add 5-hydroxymethyl furfural and erythorbic acid under light-proof condition, after stirring and dissolving, obtain water-based brightener.

[0026] The beneficial effects of the present application are:

[0027] (1) The present application optimizes the components in the additive, and prepares a water-based formula, which does not need to use organic solvents compared with traditional oil-based formula, the components have good solubility in water, can be uniformly dispersed, reduces the amount of active agent, reduces the amount of foam in galvanizing stirring, and improves the compactness of the plated layer.

[0028] (2) The additive of the present application is composed of neutral and slightly alkaline low-foam softener and 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 plated layer, and the potassium monododecyl phosphate and water-soluble polyether amine are matched, which has self-defoaming characteristics while improving wettability, and a large amount of bubbles will not be generated even under air stirring and connection of filtering device, thereby improving the process applicability.

[0029] (3) The brightener of the present application combines synergistic effect of 5-hydroxymethyl furfural, L-cysteine salt and 4-amino-2(1H) pyrimidinone to improve the brightness of the plated layer, control the deposition rate of zinc ions, and help to obtain a zinc plated layer with brightness, flatness and good ductility, compact crystal and excellent corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be further described below in conjunction with the drawings.

[0031] Figure 1 is the air stirring effect diagram of the bath solution prepared by the additive of Example 1 of the present application;

[0032] 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

[0033] 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 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.

[0034] Example 1

[0035] A low-foam acidic zinc plating additive, the additive comprising a low-foam softener and an aqueous brightener;

[0036] The low-foam softener comprises the following raw materials in percentage by mass:

[0037] Polyethyleneimine (molecular weight 10000-50000 Da) 1.0%, potassium monododecyl phosphate 0.05%, polyetheramine D230 0.4%, and the balance being water;

[0038] The aqueous brightener comprises the following raw materials:

[0039] 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.

[0040] The preparation process of the additive is as follows:

[0041] Step one, preparing the low-foam softener: add polyethyleneimine into deionized water, stir and dissolve, add polyetheramine D230, heat to 35°C, stir and dissolve, add potassium monododecyl phosphate in the form of spray, stir and mix uniformly to form the low-foam softener, and the pH is 7-9.

[0042] Step two, preparing the aqueous brightener: add citric acid and alpha-ketoglutaric acid into deionized water, stir and dissolve, then add sodium salicylate, ultrasonic dissolve, then add L-cysteine hydrochloride monohydrate and 4-amino-2(1H)pyrimidinone, mix, then add 5-hydroxymethylfurfural and erythorbic acid under light-proof condition, stir and dissolve to obtain the aqueous brightener, and the pH is 3.3-3.5.

[0043] Example 2-3

[0044] The difference from Example 1 is only that the proportion of polyethyleneimine in the low-foam softener is different, and other steps and conditions are the same as those in Example 1, and the specific proportion is shown in Table 1.

[0045] Table 1

[0046]

[0047] Example 4-5

[0048] The difference from Example 1 is only that the proportion of polyethyleneimine in the low-foam softener is different, and other steps and conditions are the same as those in Example 1, and the specific proportion is shown in Table 1.

[0049] Table 2

[0050]

[0051] Example 6-7

[0052] The difference between Example 1 and this example is that the raw material ratio of the aqueous brightener is different, and other steps and conditions are the same as Example 1. The specific ratio is shown in Table 3.

[0053] Table 3

[0054]

[0055] Comparative Example 1

[0056] The difference between Example 1 and this example is that o-chlorobenzene formaldehyde is used instead of 5-hydroxymethyl furfural in this comparative example. Other conditions and steps are the same as Example 1.

[0057] Comparative Example 2

[0058] The difference between Example 1 and this example is that benzyl propyl ketone is used instead of 4-amino-2(1H) pyrimidinone in this comparative example. Other conditions and steps are the same as Example 1.

[0059] Comparative Example 3

[0060] The difference between Example 1 and this 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 in this comparative example. Other conditions and steps are the same as Example 1.

[0061] Comparative Example 4

[0062] The difference between Example 1 and this example is that L-cysteine hydrochloride monohydrate is not added in this comparative example. Other conditions and steps are the same as Example 1.

[0063] Comparative Example 5

[0064] The difference between Example 1 and this example is that potassium monododecyl phosphate is not added in the low-foaming softener of this comparative example. Other conditions and steps are the same as Example 1.

[0065] Comparative Example 6

[0066] The difference between Example 1 and this example is that polyether amine D230 is not added in the low-foaming softener of this comparative example. Other conditions and steps are the same as Example 1.

[0067] The additives prepared by the above examples and comparative examples are added to the acid zinc plating solution for hanging plating and barrel plating to form the bath solution, as shown in Table 4:

[0068] Table 4

[0069]

[0070] The carbon steel parts were galvanized by using the above bath solution, and the test results are shown in Table 5.

[0071] Table 5

[0072]

[0073] The foam tests of the plating bath solutions of Examples 1-7, Comparative Example 5 and Comparative Example 6 were carried out. 50 mL of the bath solution was injected into a 250 mL graduated cylinder with a stopper, and the shaking and foaming were carried out for 50 times up and down. The foam volumes of 11 groups of bath solutions were recorded after standing for 0 min, 2 min, 4 min and 6 min after the shaking and foaming, and the results are shown in Table 6.

[0074] Table 6

[0075]

[0076] As shown in Table 5, the additives prepared in the examples and comparative examples were added to the acidic galvanizing plating solution to adjust the performance of the plating solution. In Example 2, the amount of polyethyleneimine as the main softening agent was reduced, and the dispersion ability of the plating solution was reduced. In Example 3, the amount of polyethyleneimine was increased compared to Example 1, and due to the properties of the high molecular polymer, the viscosity of the bath solution was increased, which was not conducive to galvanizing. In Examples 4 and 5, the ratio of potassium monododecyl phosphate and polyetheramine in the softening agent was adjusted based on Example 1. Compared with the other examples, the ratio of Example 1 was the best, and the effect was the best. In Examples 1, 5 and 6, the ratio of the water-soluble brightener was slightly adjusted, and the bath solution test results of Examples 6 and 7 were not as good as Example 1. In combination with Examples 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, the effect of the present application was better than that of the main brightener components used in the traditional additives. As shown in the foam volume of Examples 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 bath solution of Example 1 was placed in a Hull cell for air stirring, and the effect was that the foam volume was less and the stability of the plating solution was better even under the condition of air stirring. As shown in Figure 2 the bath solution of Comparative Example 6 was air stirred under the same stirring conditions as Example 1, and the foam volume was more, the stability of the bath solution was reduced, and the galvanizing effect was not as good as Example 1.

[0077] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and implementations, it is to be understood that the terminology used is for the purpose of descriptive clarity and that it is intended to be limited only by the words recited in the appended claims. It is to be understood that the terms such as first and second, etc., merely are used to differentiate one from another without necessarily requiring or implying any actual relationship or order between such entities or operations. Moreover, 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 also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0078] While the embodiments of the application have been shown and described herein, it is to be understood that the application is not limited to these embodiments and that various changes, modifications, substitutions and alterations can be made thereto without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. A low-foam acid zinc plating additive characterized by comprising, The additive comprises a low-foam softener and an aqueous brightener; The low-foam softener comprises the following raw materials in percentage by mass: Polyethyleneimine 0.8-1.2%, potassium monododecyl phosphate 0.03-0.06%, water-soluble polyetheramine 0.2-0.6%, and the rest is water; The aqueous 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%, α-ketoglutaric acid 0.3-0.5%, isoascorbic acid 0.2-0.4%, and the rest is water.

2. A low bubble acid zinc plating additive according to claim 1, characterized in that, The pH of the low-foam softener is 7-9; and the pH of the aqueous brightener is 3.3-3.

5.

3. A low bubble acid zinc plating additive according to claim 1, characterized in that, The volume ratio of the low-foam softener and the aqueous brightener in the additive is (30-40):(1-3).

4. The low bubble acid zinc plating additive according to claim 1, characterized in that, The molecular weight of the polyethyleneimine is 10000-50000 Da.

5. The low bubble acid zinc plating additive according to claim 1, characterized in that, The water-soluble polyetheramine is polyetheramine D230 and polyetheramine D400.

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

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

8. A low bubble acid zinc plating additive according to claim 1, characterized in that, 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).

9. The low bubble acid zinc plating additive according to claim 1, characterized in that, The mass ratio of the α-ketoglutaric acid and the isoascorbic acid is 1.2-1.5:

1.

10. A process for the preparation of a low-foam acid zinc plating additive according to any one of claims 1 to 9, characterized in that The method comprises the following steps: Step one, preparing the low-foam softener: adding polyethyleneimine into deionized water, stirring and dissolving, adding water-soluble polyetheramine, stirring and dissolving at a temperature of 30-40℃, and adding potassium monododecyl phosphate in the form of spray and stirring and mixing uniformly to form the low-foam softener; Step two, preparing the aqueous brightener: adding citric acid and α-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 condition, stirring and dissolving to obtain the aqueous brightener.

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