An electroforming nickel solution containing azo additives for secondary electroformed nickel mesh

Abstract

The present invention belongs to the technical field of surface treatment, and particularly relates to an electroforming nickel solution containing azo additives for secondary electroformed nickel mesh. By adding azo acid dyes to the electroforming nickel solution, due to the small steric hindrance of the azo additives, they can quickly diffuse into the interior of the mesh holes. The nickel ions in the holes have empty orbitals, which coordinate with the lone pair electrons in the additive molecules to form complexes, inhibiting the reduction of nickel ions in the holes, so that the pore diameter after adding the additives is significantly larger than that of the nickel mesh without adding additives, thereby relatively increasing the opening rate of the nickel mesh by about 4-10%. In addition, the polarization curve results show that compared with the electroforming nickel solution without additives, when using the electroforming nickel solution containing additives, the deposition potential shifts significantly negatively. The electroforming nickel solution of the present invention has the advantages of stable properties, long service life, and simple use process.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment, and in particular relates to an electroforming nickel solution containing an azo additive for secondary electroforming nickel mesh. Background Art

[0002] Nickel mesh is a round cylindrical object with small holes all over the surface. Nickel mesh is a consumable product, among which the printed nickel mesh has the largest usage and the longest history. Printed nickel mesh is made of nickel using electroforming technology. The materials required to manufacture electroformed nickel mesh include base mesh, high-purity nickel plate, electroforming liquid and DC power supply. The base mesh is the cathode and the high-purity nickel plate is the anode. Under the action of DC current, the anode nickel loses electrons and becomes nickel ions that enter the electroforming liquid. The nickel ions in the solution diffuse to the cathode through diffusion and electromigration, and obtain electrons on the cathode and are deposited as nickel atoms. Electroforming technology has many advantages such as high replication accuracy, low process cost and wide range of material selection. It is the supporting technology for the current manufacture of fine metals and has been widely used in precision molds, micro-machining, aerospace and other fields.

[0003] Electroformed nickel mesh can be manufactured using one-shot electroforming technology, which is low-cost and energy-saving. However, due to the limited manufacturing process conditions of one-shot electroforming nickel mesh, the higher the mesh count of the nickel mesh, the smaller the opening rate, which will inevitably result in the mesh of the nickel mesh with high mesh count being small, hindering the smooth flow of printing color paste. Therefore, the one-shot nickel mesh manufacturing process will affect the development of printing technology.

[0004] At present, the manufacturing of electroformed nickel mesh mostly adopts the secondary electroforming process. The secondary electroforming is to use the method of electrodeposition to put the semi-finished nickel mesh formed by the primary electroforming into the solution of the secondary electroforming tank, and use it as the cathode for electroforming and thickening, so as to replicate the same product as the primary electroformed nickel mesh. The secondary casting nickel is cast on both sides at the same time. Its advantages are large tolerance for the composition of the casting liquid, large opening rate, smooth mesh wall, good quality of printed nickel mesh, more beautiful and complex printing patterns, and broad market prospects.

[0005] At present, the flower patterns of printed fabrics on the market tend to be complex and delicate. Therefore, obtaining a mesh with finer mesh holes and capable of accommodating more slurry per unit area, that is, preparing a nickel mesh with a high aperture ratio, has become the key to improving the pattern quality. To increase the aperture ratio of the nickel mesh, the key lies in the process and additives. Improving the process can start from aspects such as improving the mold, adjusting the process conditions and process parameters. Since the electroforming nickel mesh process is already quite mature, and even with the best process, without a matching additive, the effect of increasing the aperture ratio of the nickel mesh is relatively not obvious. Therefore, it is quite important to add appropriate additives to the electroforming solution to improve the problems existing in the electroforming process. In modern electroforming, almost all electroforming technologies use organic additives. At present, the research on organic additives in China is still slow, which is due to reasons such as the long R & D cycle of organic additives, high risk, unclear analysis and maintenance methods for the electroforming solution, and slow output of results.

[0006] In the actual application of additives, it is generally considered that the effect of organic dye type electroforming additives is the best. It also has good effect in the range of relatively low current density and is easy to use. However, it has two deficiencies. One is that the additive is consumed relatively quickly during the heating process, with a short action time and high cost. The other is that there is internal stress in the cast layer, which is likely to cause reliability problems such as delamination. Summary of the Invention

[0007] The present invention provides an electroforming nickel solution containing an azo additive for increasing the aperture ratio of the secondary electroformed nickel mesh. The electroforming nickel solution comprises: nickel salt, pH buffer, pH adjuster, brightener, wetting agent, azo additive. The obtained cast layer has excellent performance and good deep electroforming property.

[0008] The additive is one or more of water-soluble acidic dyes of azobenzenesulfonic acid type.

[0009] Among them, the water-soluble acidic dye of azobenzenesulfonic acid type is one or two of methyl orange or methyl blue, preferably methyl orange, and its concentration is 1 - 30 mg / L.

[0010] Methyl orange is also known as sodium p-dimethylaminoazobenzene sulfonate, with the molecular formula C 14 H 14 N3SO3Na, relative molecular mass 327.33, molecular size 1.47 nm × 0.53 nm × 0.53 nm, and its molecular structure is as shown in Formula 1:

[0011]

[0012] The additive diffuses into the interior of the mesh holes and adsorbs on the inner wall, preventing the rapid reduction of nickel ions in the holes and resulting in the shrinkage of the pore diameter, thus playing a role in inhibiting nickel deposition.

[0013] The nickel salt is one or more of nickel sulfate, nickel chloride or nickel sulfamate, preferably nickel sulfate and nickel chloride, wherein the concentration of nickel sulfate is 50-180 g / L, and the concentration of nickel chloride is 30-50 g / L.

[0014] The pH buffer is one or more of acetic acid or boric acid, preferably boric acid, and the concentration thereof is 40-50 g / L.

[0015] The pH adjuster is one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate, preferably sodium hydroxide, with a concentration of 5wt.% to 10wt.%, and a pH range of 3.0 to 6.0.

[0016] The pH value of the electroforming nickel solution has a great influence on the quality of the casting layer. During the deposition of nickel, the pH value near the cathode area increases due to the simultaneous precipitation of hydrogen. When the pH is greater than 6, nickel hydroxide or basic nickel sulfate precipitation will be generated in the cathode area, which will be mixed in the casting layer, making the casting layer brittle, increasing porosity and generating pitting. If the pH value is too low, the amount of hydrogen precipitation will increase, and the casting layer will produce more pinholes.

[0017] The brightener is one or more of 1,4-butynediol, coumarin, and saccharin sodium, preferably 1,4-butynediol, and the concentration thereof is 0.01-1 g / L.

[0018] Brightener can not only improve the brightness of the casting layer, but also refine the grains and improve the flexibility of the casting layer. 1,4-Butynediol can also be used as a positioning agent to improve the dispersion ability of the casting liquid so that the casting layer can cover all parts of the casting in depth and breadth.

[0019] The wetting agent is one or more of sodium dodecyl sulfate and 2-ethylhexyl sodium sulfate, preferably sodium dodecyl sulfate, and the concentration thereof is 0.01-0.1 g / L.

[0020] During the nickel casting process, hydrogen is easily precipitated at the cathode. Since the overpotential of hydrogen on nickel is low, it usually adheres to the cast nickel layer to form pinholes, holes and burrs. Adding a surfactant (wetting agent) that can reduce the surface tension of the electrolyte to the casting liquid makes it difficult for hydrogen or colloidal particles to adhere to the surface of the cast nickel layer.

[0021] The present invention also provides a method for electroforming using the above-mentioned electroforming nickel solution, characterized in that the process conditions of the electroforming nickel mesh are: the anode is a soluble nickel plate with a purity of 99.99%, and the cathode is a base nickel mesh. The current density is 5-10A / dm 2 , temperature 30-55°C, time 30-80min, electrode spacing 2-8cm, stirring speed 100-1000rpm.

[0022] The beneficial effects of the present invention are:

[0023] In the present invention, an azo additive is added to the electroforming nickel solution. This type of additive has stable properties, a long acting time during the electroforming process, a small dosage, and remarkable effects. In addition, the azo dye additive is not easily decomposed, reducing the accumulation of organic impurities on the surface of the casting layer, thereby reducing the internal stress of the casting layer.

[0024] The methyl orange molecule not only contains conjugated double bonds, but also has atoms with lone electron pairs on the conjugated system, such as oxygen, nitrogen, etc., which enable it to form stable complexes with certain metal ions. During the nickel deposition process, the methyl orange molecule occupies a small space, and the resistance of its molecule to diffuse into the pores is small. It can quickly diffuse into the pores and adsorb on the inner wall of the pores, inhibiting the reduction of nickel in the pores, thereby effectively improving the aperture ratio of the nickel mesh.

[0025] The electroforming nickel solution formula of the present invention is simple to prepare, easy to maintain, and has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Metallographic picture of the cross-section of the pores of the nickel mesh after electroforming.

[0027] Figure 2 Variation curve of the aperture ratio (K / %) of the electroformed nickel mesh.

[0028] Figure 3 Linear sweep voltammetry curve of methyl orange on the nickel deposition process. DETAILED DESCRIPTION OF THE INVENTION

[0029] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings. The following examples or experimental data are intended to exemplarily illustrate the present invention, and those skilled in the art should clearly understand that the present invention is not limited to these examples or experimental data.

[0030] Electroforming area of the nickel mesh: Use a cutting tool to cut the substrate mesh into an experimental nickel mesh with a size of 60 mm × 50 mm. Use electroforming tape to control the actual electroforming area of the nickel mesh at 50 mm × 40 mm.

[0031] Pretreatment conditions:

[0032] (1) Alkali washing: Alkali wash the cut substrate mesh, remove the grease and organic substances on the surface, and then rinse the sample with deionized water. The composition of the alkali washing solution is: 15 g / L of sodium hydroxide, 50 g / L of sodium carbonate, 50 g / L of sodium phosphate, and 10 g / L of sodium silicate. The alkali washing temperature is 60 °C, and the alkali washing time is 2 min.

[0033] (2) Acid washing: Place the above substrate mesh in the acid washing solution to remove the oxide film and impurity ions on its surface, and then rinse the sample clean with deionized water. The composition of the acid washing solution is: 5 wt.% dilute sulfuric acid. Acid washing temperature: 25 °C; acid washing time: 1 min.

[0034] (3) Dehydration: Blow-dry the substrate mesh after pickling in step (2) with cold air and store for later use.

[0035] The open area ratio refers to the percentage of the total area of the mesh holes in a unit area to the unit area. The open area ratio affects the transportation of the printing color paste. The nickel mesh with a high open area ratio has better color penetration ability and printing quality. Increasing the open area ratio can reduce the particle size requirements of the printing paste, reduce the blockage of holes and the resistance of paste discharge, and improve production efficiency. For standard nickel meshes, the open area ratio can be theoretically calculated by the following formula:

[0036] K / % = (d / D) 2 × 100

[0037] Where: K - open area ratio / %; d - hole diameter; D - hole pitch.

[0038] Example 1

[0039] Composition of the nickel casting solution: nickel sulfate 50 g / L, nickel chloride 45 g / L, boric acid 40 g / L, 1,4-butyne diol 0.01 g / L, sodium dodecyl sulfate 0.01 g / L, adjust the pH of the casting solution to 5 with 3 wt.% dilute sodium hydroxide, and add methyl orange 1 mg / L.

[0040] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the substrate nickel mesh after pretreatment, the distance between the anode and the cathode is 5 cm, the stirring speed is 750 rpm, the current density is 5 A / dm 2 , the temperature is 50 °C, and the electroforming time is 48 min. The metallographic picture of the cross-section of the nickel mesh holes after secondary electroforming is shown in Figure 1 a, and the calculation result of the open area ratio is shown in Figure 2 .

[0041] Example 2

[0042] Composition of the nickel casting solution: nickel sulfate 150 g / L, nickel chloride 40 g / L, boric acid 50 g / L, 1,4-butyne diol 0.28 g / L, sodium dodecyl sulfate 0.1 g / L, adjust the pH of the casting solution to 4.5 with 3 wt.% dilute sodium hydroxide, and add methyl orange 5 mg / L.

[0043] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the substrate nickel mesh after pretreatment, the distance between the anode and the cathode is 5 cm, the stirring speed is 750 rpm, the current density is 8 A / dm 2 , the temperature is 40 °C, and the electroforming time is 45 min. The metallographic picture of the cross-section of the nickel mesh holes after secondary electroforming is shown in Figure 1 b, and the calculation result of the open area ratio is shown in Figure 2 .

[0044] Example 3

[0045] Composition of nickel electroforming solution: nickel sulfate 150 g / L, nickel chloride 40 g / L, boric acid 50 g / L, 1,4 - butynediol 0.28 g / L, sodium dodecyl sulfate 0.1 g / L, adjust the pH of the electroforming solution to 4.5 with 3 wt.% dilute sodium hydroxide, and add methyl orange 30 mg / L.

[0046] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the pretreated substrate nickel mesh, the distance between the anode and cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 8 A / dm 2 , the temperature is 40 °C, and the electroforming time is 45 min. The metallographic pictures of the cross-section of the nickel mesh holes after secondary electroforming are shown in Figure 1 c, and the calculation results of the porosity are shown in Figure 2 .

[0047] Example 4

[0048] Composition of nickel electroforming solution: nickel sulfate 180 g / L, nickel chloride 30 g / L, boric acid 45 g / L, 1,4 - butynediol 0.5 g / L, sodium dodecyl sulfate 0.1 g / L, adjust the pH of the electroforming solution to 4 with 3 wt.% dilute sodium hydroxide, and add methyl orange 10 mg / L.

[0049] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the pretreated substrate nickel mesh, the distance between the anode and cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 10 A / dm 2 , the temperature is 30 °C, and the electroforming time is 44 min. The metallographic pictures of the cross-section of the nickel mesh holes after secondary electroforming are shown in Figure 1 d, and the calculation results of the porosity are shown in Figure 2 .

[0050] Example 5

[0051] Composition of nickel electroforming solution: nickel sulfate 80 g / L, nickel chloride 50 g / L, boric acid 42 g / L, 1,4 - butynediol 0.3 g / L, sodium dodecyl sulfate 0.08 g / L, adjust the pH of the electroforming solution to 3 with 3 wt.% dilute sodium hydroxide, and add methyl orange 3 mg / L.

[0052] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the pretreated substrate nickel mesh, the distance between the anode and cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 9 A / dm 2 , the temperature is 40 °C, and the electroforming time is 47 min. The metallographic pictures of the cross-section of the nickel mesh holes after secondary electroforming are shown in Figure 1 e, and the calculation results of the porosity are shown inFigure 2 .

[0053] Example 6

[0054] Composition of nickel electroforming solution: nickel sulfate 150 g / L, nickel chloride 40 g / L, boric acid 50 g / L, 1,4-butyne diol 0.28 g / L, sodium dodecyl sulfate 0.1 g / L, 3 wt.% dilute sodium hydroxide is used to adjust the pH of the electroforming solution to 4.5, and methylene blue 5 mg / L is added.

[0055] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the substrate nickel mesh after pretreatment, the distance between the anode and the cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 8 A / dm 2 , the temperature is 40 °C, and the electroforming time is 45 min. The metallographic picture of the cross-section of the nickel mesh pores after secondary electroforming is shown in Figure 1 f, and the calculation result of the porosity is shown in Figure 2 .

[0056] Example 7

[0057] Composition of nickel electroforming solution: nickel sulfate 180 g / L, nickel chloride 30 g / L, boric acid 45 g / L, 1,4-butyne diol 0.5 g / L, sodium dodecyl sulfate 0.1 g / L, 3 wt.% dilute sodium hydroxide is used to adjust the pH of the electroforming solution to 6, and methyl orange 10 mg / L is added.

[0058] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the substrate nickel mesh after pretreatment, the distance between the anode and the cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 10 A / dm 2 , the temperature is 30 °C, and the electroforming time is 44 min. The metallographic picture of the cross-section of the nickel mesh pores after secondary electroforming is shown in Figure 1 g, and the calculation result of the porosity is shown in Figure 2 .

[0059] Example 8

[0060] Composition of nickel electroforming solution: nickel sulfate 80 g / L, nickel chloride 50 g / L, boric acid 42 g / L, saccharin sodium 0.3 g / L, sodium dodecyl sulfate 0.08 g / L, 3 wt.% dilute sodium hydroxide is used to adjust the pH of the electroforming solution to 3, and methyl orange 3 mg / L is added.

[0061] Electroforming process conditions: 250 mL Hull cell, the anode is a soluble nickel plate with a purity of 99.99%, the cathode is the substrate nickel mesh after pretreatment, the distance between the anode and the cathode is 5 cm, the stirring speed is 750 rpm, and the current density is 9 A / dm 2, the temperature was 40 °C, and the electroforming time was 47 min. The metallographic pictures of the cross-section of the nickel mesh holes after secondary electroforming are shown in Figure 1 h, and the calculation results of the opening rate are shown in Figure 2 .

[0062] Comparative Example 1

[0063] Composition of electroformed nickel solution: nickel sulfate 150 g / L, nickel chloride 40 g / L, boric acid 50 g / L, 1,4-butyne diol 0.28 g / L, sodium dodecyl sulfate 0.1 g / L, 3 wt.% dilute sodium hydroxide was used to adjust the pH of the electroforming solution to 4.5, and methyl orange was not added to the above electroforming solution.

[0064] Electroforming process conditions: 250 mL Hull cell, the anode was a soluble nickel plate with a purity of 99.99%, the cathode was the substrate nickel mesh after pretreatment, the distance between the anode and cathode was 5 cm, the stirring speed was 750 rpm, and the current density was 8 A / dm 2 , the temperature was 40 °C, and the electroforming time was 45 min. The metallographic pictures of the cross-section of the nickel mesh holes after secondary electroforming are shown in Figure 1 i, and the calculation results of the opening rate are shown in Figure 2 .

[0065] The metallographic observation, opening rate calculation and polarization curve test were carried out on the nickel mesh after electroforming obtained in the above examples.

[0066] The opening rate was calculated as follows: The aperture of the nickel mesh was observed using a metallographic microscope, and the size of the nickel mesh holes was measured. The measured aperture size distribution range of the nickel mesh was between 50 and 90 μm, and the opening rate was calculated through the formula.

[0067] The method for testing the polarization curve was as follows: Linear sweep voltammetry was used to study the effect of additives on the nickel ion deposition process. The electrochemical test of the electroforming solution was completed in a three-electrode system. The working electrode was a platinum disk electrode, the platinum sheet electrode was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode. The potential scanning range was 0.8 V to -1.5 V, and the scanning rate was 5 mV / s.

[0068] Figure 1 and Figure 2 respectively show the metallographic pictures and the calculation results of the opening rate obtained in the above examples and comparative examples. Comparing Examples 1-8 with Comparative Example 1, it can be seen that after electroforming with methyl orange added, the aperture of the mesh holes increased and the opening rate increased, indicating that methyl orange is effective in increasing the opening rate of the nickel mesh. Comparing Example 2 with Comparative Example 1, the opening rate of the nickel mesh increased significantly, while comparing Example 3 with Comparative Example 1, the opening rate of the nickel mesh hardly increased, indicating that when the concentration of methyl orange is low, its effect of inhibiting nickel deposition is better, and methyl orange can only play a role in inhibiting the deposition of nickel ions in the holes within a suitable concentration range.

[0069] In this experiment, the effect of additives on nickel deposition was characterized by polarization curves. Figure 3 The polarization curve test results of the above embodiments are shown. Comparing Examples 1-8 with Comparative Example 1, for the polarization curve measured from the casting solution after adding methyl orange, the potential shifted negatively by about 15-50 mV. Among them, for Example 2 compared with Comparative Example 1, the negative shift of the potential was the most obvious, about 50 mV, indicating that adding methyl orange can effectively inhibit the reduction of nickel ions.

[0070] In summary, the electroforming nickel solution prepared according to the method of the present invention can significantly increase the aperture ratio of the nickel mesh. Compared with the electroforming nickel solution without additives, the aperture ratio is increased by about 4-10%, and the polarization results show that the potential of the electroforming solution with additives shifted significantly negatively.

[0071] The above embodiments and accompanying drawings are further descriptions of the technical solutions of the present invention, but are not limited to the above embodiments and accompanying drawings. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be included in the protection scope of the present invention.

Claims

1. An electroforming nickel solution containing an azo additive, characterized in that, The electroforming nickel solution consists of: nickel salt, pH buffer, pH adjuster, brightener, wetting agent, azo additive and water; The pH buffer is one or two of acetic acid or boric acid, and the concentration of boric acid is 40-50 g / L; The pH adjuster is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate. Among them, the concentration of sodium hydroxide is 5wt.% - 10 wt.%, and the pH range is 3.0 - 6.0; The azo additive is methyl orange, and its concentration is 3-10 mg / L.

2. The electroforming nickel solution according to claim 1, wherein The nickel salt is one or more of nickel sulfate, nickel chloride or nickel sulfamate. Among them, the concentration of nickel sulfate is 50-180 g / L, and the concentration of nickel chloride is 30-50 g / L.

3. The electroforming nickel solution according to claim 1, wherein The brightener is one or more of 1,4-butyne diol, coumarin, sodium saccharin. Among them, the concentration of 1,4-butyne diol is 0.01-1 g / L.

4. The electroforming nickel solution according to claim 1, characterized in that, The wetting agent is one or more of sodium dodecyl sulfate, sodium 2-ethylhexyl sulfate. Among them, the concentration of sodium dodecyl sulfate is 0.01-0.1 g / L.

5. Use of an electroformed nickel solution as described in claim 1, characterized in that, The electroforming nickel solution is used as the electroforming nickel solution for secondary electroforming nickel mesh.

6. The application of the electroforming nickel solution according to claim 5, characterized in that, The process conditions for electroforming the nickel mesh are as follows: the anode is a soluble nickel plate with a purity of 99.99%, and the cathode is the substrate nickel mesh; the current density is 5 - 10 A / dm 2 , the temperature is 30 - 55 °C, the time is 30 - 80 min, the electrode spacing is 2 - 8 cm, and the stirring speed is 100 - 1000 rpm.

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