BRPI0820988B1 - galvanic bath, process for galvanic separation and use of a bipolar diaphragm for separation in a galvanic bath and use of a bipolar diaphragm to prevent anodic decomposition - Google Patents

Description

(54) Title: GALVANIC BATH, PROCESS FOR GALVANIC SEPARATION AND USE OF A BIPOLAR DIAPHRAGM FOR SEPARATION IN A GALVANIC BATH AND USE OF A BI POLAR DIAPHRAGM TO AVOID ANODIC DECOMPOSITION (73) Owner: Sociedade VENTãA GMBH,. Address: Stadtring Nordhorn 116, 33334 Gütersloh, GERMANY (DE) (72) Inventor: HARTMUTTRENKNER; ALEXANDER JIMENEZ.

Validity Period: 20 (twenty) years from 12/15/2008, subject to legal conditions

Issued on: 12/04/2018

Digitally signed by:

Liane Elizabeth Caldeira Lage

Director of Patents, Computer Programs and Topographies of Integrated Circuits

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Invention Patent Report for GALVANIC BATH, PROCESS FOR GALVANIC SEPARATION AND USE OF A BIPOLAR DIAPHRAGM FOR SEPARATION IN A GALVANIC BATH AND USE OF A BIPOLAR DIAPHRAGM TO PREVENT ANODIC DECOMPOSITION.

[001] The present invention relates to an alkaline galvanic bath for the application of zinc or zinc alloys on substrates, in which the anode and cathode compartments are reciprocally separated by a bipolar diaphragm. The galvanic bath is operated with zinc, that is, with zinc alloy baths, which may contain other additives. In addition, the invention encompasses a process for galvanically separating zinc or zinc alloys from the substrate into which the substrate is introduced into the galvanic bath according to the invention. In addition, the invention relates to the use of bipolar diaphragms for the separation of anode compartment and cathode compartment in galvanic baths and to prevent the anodic decomposition of organic components of the electrolyte in galvanic baths.

[002] To make the separation of additional layers of zinc baths feasible, organic shine builders and humectants will be added to the bath. In addition, the bath contains complex builders to allow the separation of other metals from the zinc alloy. The complex builder serves to regularize the potential and to keep the metals in the solution so that the desired alloy composition is achieved. The use of the aforementioned organic components results, however, in the operation of the baths in problems, as well as described in WO 00/06807. There, it is perceived especially as a disadvantage factor that these baths, after a few hours of operation, present a change from the original blue-violet color in the direction of brown. The brown color originates from

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2/14 decomposition products whose quantity increases over the bath's operating time. After several weeks, that is, months, this coloration becomes more reinforced, this produces considerable interference in the coating of the pieces, such as, for example, thicknesses of irregular layers or formation of bubbles. Continuous cleaning of the bath is therefore essential. But this process takes time and costs.

[003] With the separation of phases and increasing content of organic impurities, decorative problems in the coating gradually appear and result in reduced productivity. In order to reduce decorative problems, higher dosages of organic bath additives are usually carried out, however, the content of decomposition products continues to increase.

[004] As auxiliary measures so far, the following methods are known:

• a dilution of the bath reduces the concentration of impurities proportional to the degree of dilution. A dilution is simple to perform, but it has the disadvantage that the amount of electrolyte removed from the bath will have to be conducted for cost-intensive disposal. A totally new bath can in this context be considered as a special case of bath dilution.

• a treatment of active charcoal by mixing active charcoal in the amount of 0.5-2 g / L in the bath and subsequent filtration avoids the concentration of impurities by adsorption on the charcoal. The disadvantage of this method is that it is quite laborious and produces only a small reduction.

• alkaline zinc baths contain organic additives in a lower portion by a factor of 5 to 10 than acid baths. Correspondingly, impurity from decomposition products is usually less critical. In the case of alkaline alloy baths,

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3/14 however, for the complexation of the alloy additive (Fe, Co, Ni, Sn, Mn) it is necessary to add considerable amounts of organic complex builders. These will be decomposed oxidatively in the anode and the accumulated decomposition products act negatively on the production process.

• EP 1 369 505 A2 discloses a process for cleaning a zinc / nickel electrolyte in a galvanic process in which a portion of the process bath employed in the process is applied by vaporization until a phase separation occurs in one lower phase, at least one intermediate phase and an upper phase, the lower phase and the upper phase being separated. This process requires several steps and due to the energy needs it presents, it is disadvantageous from a cost point of view.

• WO 00/06807 and WO 01/96631 describe galvanic baths for the application of zinc / nickel coatings. To avoid unwanted decomposition of additives in the anode, it is proposed to separate the anode from the alkaline electrolyte through an ion exchange diaphragm.

[005] However, these systems have the disadvantage that the use of these diaphragms produces a volumetric excess in the global system.

[006] In addition, baths known according to the state of the art that are operated without separating the region of the cathodes and anodes, have the disadvantage that in the anodic decomposition of the nitrogen-forming complex, cyanide is formed and it is enriched in a concentration that cannot be neglected.

[007] Starting from this situation, it is the objective of the present invention to offer an alkaline galvanic bath that eliminates the aforementioned disadvantages, being simple to operate and allowing Petition 870180128959, of 9/11/2018, p. 8/27

4/14 the high durability of the galvanic bath. At the same time, galvanic separation with unchanged layer thickness should be made possible.

[008] According to the invention, an alkaline galvanic bath is offered for the separation of zinc or zinc alloys from substrates containing a cathode compartment with a corresponding cathode cathode containing zinc ions and anode compartment with anode and corresponding anolyte, the cathode compartment and the anode compartment being separated by a separator. According to the invention, a bipolar diaphragm is used as a separator.

[009] The galvanic bath according to the invention has the following economic and ecological advantages in this case:

a) bath durability is increased,

b) saving sodium hydroxide by the automatic formation process in the anolyte after the fission of water,

c) reduction of excess volume in the galvanic zinc electrolyte,

d) oxidation reactions of organic additives in the anode are avoided,

e) obtaining a high degree of efficiency in the separation of metal in the cathode around approximately 90% degree of effectiveness,

f) optimized utilization of the chemical components of the electrolyte because no excess volume has been formed that had to be additionally treated for wastewater, or eliminated, however, a volumetric reduction is registered due to the loss of mass in metals and hydrogen in the electrolyte during the process of separation, which, according to the sodium hydroxide content in the electrolyte, can be compensated with water, sodium hydroxide or sodium bleach from

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5/14 of the anolyte,

g) in its use a high quality layer thickness unchanged on the coated substrate is obtained.

[0010] The bipolar diaphragm has at least one cation exchange diaphragm, at least one anion exchange diaphragm and an intermediate layer formed between these diaphragms, which catalyzes the dissociation of water and protons and hydroxide ions. [0011] The anode preferably consists of nickel, nickel-plated noble steel, steel, or noble steel. This has the advantage compared to the galvanic baths known in the state of the art, in which platinum titanium anodes are normally used, being of significantly greater cost.

[0012] Preferably the catholyte contains other metallic salts. This includes iron, nickel, manganese, cobalt and tin salts or mixtures thereof. Likewise, the catholyte complex builder may contain especially amines, polyalkyleneimines, dicarboxylic acids, tricarboxylic acids, hydroxycarboxylic acids, other chelate binders, such as acetyl acetone, urea, urea derivatives and other complex binders, in which the functional group complexation nitrogen phosphorus and sulfur are present. Other optional components in catholites are additive substances selected from the group consisting of gloss media, humectants and their mixtures. This includes, preferably, benzylpyridinium carboxylate, nicotinic acid, methylpyridinium N-carboxylate and aldehydes.

[0013] The following is a composition exemplified as a catholyte according to the invention:

[0014] 80-250 g / l sodium or potassium hydroxide, [0015] 4-50 g / l zinc in the form of soluble zinc salt, [0016] 0.02-20 g / l Nickel, Iron, Cobalt, Tin in the form of a metal salt soluble as alloy metal,

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6/14 [0017] 1-200 g / l Complex builder selected from the group consisting of Polyalkyleneamines, Alcanolamines, Polyhydroxycarboxylates and their mixtures and [0018] 0.1-5 g / l aromatic and / or heteroaromatic gloss builders.

[0019] Preferably, the anolyte consists of 50 to 200 g / l of NaOH and 950 to 800 g / l of water.

[0020] The bipolar diaphragm preferably has thermal stability up to 50 ° C, especially preferred up to 60 ° C.

[0021] Another variant according to the invention of the galvanic bath provides that it has another electrolyte compartment, disposed between the cathode and anode compartment. This other electrolyte space will be separated by the bipolar diaphragm of the anode compartment by an ion exchange diaphragm in the cathode compartment. In this electrolyte compartment is contained a second catholyte.

[0022] In this case it is preferred that the ion exchange diaphragm is an anion exchange diaphragm. But it is also possible to employ a cation exchange diaphragm.

[0023] The second catholyte preferably has a pH in the range of 1 to 7. Especially preferably the second catholyte contains sulfuric acid or sulfuric acid and sodium sulfate. It is also possible that they are contained in the second carboxylic acid catholyte and / or its salts, for example, sodium formate or sodium acetate.

[0024] The use of a second catheter serves, in this case, to protect the bipolar diaphragm. Thus, hydrogen carbonate ions (HCO3-) on the catholyte side from the bipolar diaphragm with the formed protons (H +), can form carbonic acid from water fission, which decomposes as carbon dioxide (CO2) and water. O

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7/14 carbon dioxide in formation can press in the direction of the removal of the diaphragms of cations and anions from the bipolar diaphragm on the connection face, with which the function of water fission in protons and hydroxide ions is progressively lost. By the additional ion exchange diaphragm, especially an anion exchange diaphragm, especially hydroxide ions are present with direct current applied to the second catholyte, when neutralization, hydrogen carbonate decomposition increases the pH value. In this way, it is possible to ensure that the bipolar diaphragm on the cation exchange side is no longer harmed by the hydrogen carbonate ions.

[0025] According to the invention, a process for galvanic separation and zinc or zinc alloys in substrates is also offered, in which the substrate is introduced into a galvanic bath as described above, with the substrate being separated in galvanic processes. zinc or zinc alloys.

[0026] The separation takes place in the case preferably at a temperature of 20 to 40 ° C especially preferred at a temperature of 20 ° C the current density is applied to the separation preferably in a range of 0.1 to 20 A / dm ² , especially 0.5 to 3 A / dm ² .

[0027] According to the invention, it will also be offered the use of a bipolar diaphragm to separate the anode compartment and the cathode compartment in a galvanic bath. The bipolar diaphragm makes it possible to avoid the anodic composition of organic components of the electrolyte in a galvanic bath. [0028] The bipolar diaphragm, used according to the invention, preferably presents at least one cation exchange diaphragm, at least one anion exchange diaphragm and an intermediate layer integrated between the diaphragms with a catalytic effect on

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8/14 the deoxidation of water in protons and hydroxide ions.

[0029] The bipolar diaphragms of the present invention, using conventional ion exchange diaphragms, can be produced. Bipolar diaphragms can, for example, be produced by copolymerization of styrene and divinylbenzene or butadiene or by copolymerization of acrylonitrile and butadiene, with cations being linked, for example, by a sulfochlorination firmly in the diaphragm and anions, by means of chloromethylization and reaction with tertiary amines are firmly attached to the diaphragm. The thickness of the bipolar diaphragms is preferably between approximately 0.1 and 1 mm. In addition, bipolar diaphragms may optionally include reinforcement material of different types and shapes depending on the process with which cation exchange diaphragms are produced.

[0030] The bipolar diaphragms of the present invention can be produced with any conventional cation exchange diaphragm, including diaphragms with an ion exchange group with a sulfonic acid group or a carbon acid group. The most preferred cation exchange diaphragms include a sulfonic acid group that retains an exchange group even under acidic conditions. In addition, the cation exchange diaphragm may include a reduced amount of an anion exchange group, provided that it has cation transport numbers of not less than 0.9.

[0031] The anion exchange layer can be produced with any conventional anion exchange material with such ion exchange groups as positively charged organic ions, amino groups or quarterly ammonium groups. The polymeric diaphragm structure would contain the anion exchange group integrated in the organic mesh. The polymer can be a vinylpyridine polymer, divinylbenzene with the copolimerized monomers in different amounts as

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9/14 styrene, ethylene, methacrylic acid or propylene. The anion exchange diaphragm can have a reinforcement matrix such as polyethylene, polypropylene, polyvinyl chloride and polyvinyl acetate. The anion exchange diaphragm will preferably have a capacity between approximately 1 and 3 milliequivalents per gram (mval / g). The anion exchange diaphragm can be a polymerizable type, a homogeneous type or a non-homogeneous type.

[0032] According to the invention, the ion exchange diaphragms will preferably be interconnected using an adhesive such as, for example, ionic glue that consists of positive and negative charge species. These adhesives include, without restriction, epichlorohydrin, polyethylamine, polyacrylic acid, polyvinylamine, poly (4vinyl) pyridine, sprayed and marketed anion and cation exchange resin and combinations thereof. After the application of the ionic adhesive, the cation-conducting material and the anion-conducting material will be hot pressed, preferably with a variety of elements with sufficient temperature and sufficient pressure so that the material is connected in the form of a bipolar diaphragm. The removable elements can be removed by extraction or dissolution, leaving a passage for fluids. A preferred glue is an aqueous solution containing a mixture of polyacrylic and polyethyleneimine, especially preferred in a polyethyleneimine: polyacrylic acid ratio of approximately 6: 1.

[0033] Alternatively the glue can include a polyvinylamine, in which the amino group is replaced by an alkyl group with 1 to 4 carbon atoms and the polyvinylamine having a molecular weight between approximately 10 ⁴ and 10 ⁶ . The concentration of the aqueous polyvinyl solution can be between 0.5 and 70% by weight, however, the preferred concentration will be between approximately 3 and 15% by weight. Aqueous polyvinylamine solutions can be obtained as, for example,

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10/14 example, with a conventional acid or alkaline hydrolysis process of polyvinyl formamide or polyvinyl acetamide with a solution of sodium hydroxide or hydrochloric acid. A preferred process for producing an aqueous polyvinyl solution includes hydrolyzing aqueous polyvinylformamide with hydrochloric acid at a temperature between approximately 60 ° C and 100 ° C. The concentration of polyvinylformamide in the water is preferably between approximately 1 and 50% by weight, more preferably approximately between 5 and 20% by weight. The resulting polyvinylamine solutions are still liquefied and can be easily applied to the diaphragms.

[0034] Glue solutions can be applied using any conventional technique, including brushes or roller coatings, on one or both ion exchange diaphragms. The solution will preferably be applied at a temperature between approximately 10 ° and 50 ° C. It is also possible to impregnate the diaphragms on both sides with the solution. The outer surface of the diaphragm will, however, preferably be washed during the production of the bipolar diaphragm, removing the glue. The thickness of the glue layer is preferably between approximately 0.001 and approximately 0.05 mm.

[0035] In the bipolar diaphragm of the present invention the cation exchange diaphragm can be connected in any process to the anion exchange diaphragm. However, it is preferred that the cation exchange diaphragm and the anion exchange diaphragm are glued together, with a removal resistance of not less than 0.2 kg f / 25 mm in a wet state in order to avoid a separation of the two diaphragms when the bipolar diaphragm is used in a wet state as possibly in the fission of water. A bipolar diaphragm with reduced resistance to removal will allow blisters or inclusions to form on the boundary face between the diaphragm during use. Petition 870180128959, of 9/11/2018, pg. 15/27

11/14 an anion conductor and the cation conducting diaphragm. Bubbles and inclusions produce a decrease in flow efficiency on each diaphragm surface and a progressive increase over longer periods of use of the diaphragm potential. Such diaphragms need to be replaced periodically.

[0036] Especially preferred will be a diaphragm with the following parameters mentioned in table 1.

TABLE 1

Mechanical Fabric Reinforcement PEEK monofil Voltage Drop @ 1 KA / m ² @ 30 ° C, 5% H2SO4 <1.20 volt Water Fission Efficiency > 98% Nominal thickness 180 pm Diaphragm Structure (Kraton, PPO) Homogeneous Film

[0037] Based on the following figure and examples, the object according to the invention should be described in more detail without restricting it to the special forms of execution presented here.

[0038] Figure 1 shows, based on a schematic representation, the structure of a galvanic bath, according to the invention and the chemical reaction that takes place there.

[0039] Figure 2 shows, based on a schematic representation, the structure of another galvanic bath according to the invention with the chemical reactions that take place in them.

[0040] Figure 1 schematically shows the galvanic bath according to the invention. There the number 1 means the bath, the number 2 represents the anodes and the number 3 represents the cathodes, that is, the part to be coated. Anolyte 4 surrounding the anode and catholyte 5 surrounding the cathode are also shown. Anolyte and catholyte are reciprocally separated by a bipolar diaphragm 6.

[0041] In the bath according to the invention the compartment of the

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12/14 anode is preferably configured smaller than the cathode compartment, since special processes take place there. In the galvanic bath, the electrochemical processes shown in Table 2 are used in this case:

TABLE 2 (1) Zn ⁺⁺ + 2 e -> Zn (Metal Separation in the Cathode) (2) Ni ++ + 2 and 'Ni (Metal Separation in the Cathode) (3) Na ⁺ + θ'θ Na (Corresponding Reaction Cathode Load Support Transport System) (4) Na + + OH θ NaOH (NaOH dissociation reaction in anolyte) (5) 4 H2O 4 4 H + +4 OH (Water Fission Reaction in the Middle Diaphragm Layer) ( 6) 4 OH- 2H2O + 02 t (Anode Reaction) (7) OH + Η θ H2O (Reaction with Protons resulting in Water Fission in the Catholite) (8) OH- + Na + θ NaOH (NaOH Dissociation in the Cathode) (9) 4 H ⁺ + 4 and '2H ² (Proton Cathode Reaction) (10) Amines + Zn ⁺⁺ θ Amine-Zn Complex Compounds (partly anions) Amines + Ni ++ θ Anion Amino Ni Complex Compounds (partly anions) [0042] Figure 2 shows the galvanic bath of figure 1, which additionally contains between the cathode compartment and the anode compartment, another electrolyte compartment that in turn contains a second catholyte 7, which , in the present case, contains su l sodium phosphate and hydrogen sulphide (always 1M), the additional electrolyte compartment being separated from the cathode compartment by an ion exchange diaphragm 6. With this variant of the invention, the formation of CO2 in the bipolar diaphragm can be avoided. Carbon dioxide formed may forcibly move the diaphragm away

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13/14 cation and anion of the bipolar diaphragm on the interconnecting face, which can be avoided by another ion exchange diaphragm.

EXAMPLE 1 [0043] A galvanic bath was prepared for the separation of zinc-nickel alloys:

• Zinc 10.4 g / L (as soluble Zno), • Nickel 1.2 g / L (as nickel sulfate), • NaOH 120 g / L, • Tetraethylenepentamine 25 g / L, • Triethanolamine 10 g / L, • Addition of brightness 0.1 g / L, [0044] This bath was operated with a bipolar diaphragm. The bipolar diaphragm was introduced into the bath between the anode and the cathode. Then, iron plates (7x10 cm) were used as parts to be coated, which are commonly used for testing Hull cells, and being coated at a current density of 1 to 2 A / dm ² . The movement of the iron sheets means mechanically with a speed of 1.4 m / min.

[0045] Then, the baths were analyzed and regularly supplemented. The sequential dosage of the baths was verified according to the results of the Hull cell tests. A conventional drag in production baths of 12 L of bath / 10,000 Ah was also taken into account and the bath components were correspondingly complemented.

EXAMPLE 2 [0046] A galvanic bath was produced for the separation of zinc with the following components:

• Zinc 16, g / L (as soluble Zno), • Iron 0.4 g / L (as iron sulfate), • NaOH 120 g / L,

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14/14 • Triethanolamine 50 g / L, • Addition of gloss 0.1 g / L, [0047] This bath was operated with a bipolar diaphragm. The bipolar diaphragm was introduced into the bath between the anode and the cathode. Then, iron plates (7x10 cm) were used as parts to be coated, which are commonly used for testing Hull cells, and being coated at a current density of 1 to 2 A / dm ² . The movement of the iron sheets means mechanically with a speed of 1.4 m / min.

[0048] Then, the baths were analyzed and regularly supplemented. The sequential dosage of the baths was verified according to the results of the Hull cell tests. A conventional drag in production baths of 12 L of bath / 10,000 Ah was also taken into account and the bath components were correspondingly complemented.

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Claims (21)

1. Galvanic alkaline bath for separating zinc or zinc alloy in substrates, containing at least one cathode compartment with corresponding cathode and catholites containing zinc ions and at least one anode compartment with corresponding anode and anolytes, the compartment being the cathode is separated from the anode compartment by a separator, characterized by the fact that the separator is a bipolar diaphragm, the galvanic bath having another electrolyte compartment, which is separated by the bipolar diaphragm of the anode compartment, and, by an ion exchange diaphragm from the cathode compartment and a second catholyte. 2. Galvanic bath according to claim 1, characterized by the fact that the bipolar diaphragm contains at least one cation exchange diaphragm, at least one anion exchange diaphragm and an intermediate layer integrated between the diaphragms that produces the catalyst dissociation of water in protons and hydroxide ions. 3. Galvanic bath according to claim 2, characterized by the fact that the cation exchange diaphragm comprises at least the material, selected partially or completely from fluorinated polymers with carboxylic acids or functional sulfonic acid groups, ethylene copolymers with acid acrylic, ethylene copolymers with methacrylic acid, styrene polymers with carboxylic acid-functional groups or functional sulfonic acid groups, polymers-divinylbenzene with functional carboxylic acid groups or sulfonic-functional acid groups, derivatives and mixtures thereof. 4. Galvanic bath according to claim 2 or 3, characterized by the fact that the anion exchange diaphragm covers at least the material selected from polymers with priPetition chains 870180128959, from 9/11/2018, p. 20/27 2/4 mária (main chains) partially or totally fluoridated, saturated hydrocarbon primary chains, unsaturated primary chains, aromatic or partially aromatic primary chains or saturated primary chains, containing hetero atoms, with selected functional groups of positive charge functionalities, and their amines and derivatives. 5. Galvanic bath according to any one of claims 2 to 4, characterized in that the anion exchange diaphragm contains a divinylpyridine or divinylbenzene polymer with monomers that are comprised of the group consisting of styrene, ethylene, methacrylic acid and / or propylene . 6. Galvanic bath according to any one of the preceding claims, characterized in that the bipolar diaphragm is thermally stable up to 50 ° C, especially 60 ° C. 7. Galvanic bath according to any one of the preceding claims, characterized in that the anode consists of nickel or essentially contains nickel. 8. Galvanic bath according to any of the preceding claims, characterized by the fact that the catholyte contains other metal salts, especially iron, nickel, manganese, cobalt and tin or their mixtures. Galvanic bath according to any one of the preceding claims, characterized in that the catholyte contains complex builders, especially of amines, polyalkyleneimines, dicarboxylic acids, tricarboxylic acids, carboxylic hydroxide, other chelate binders, such as acetyl acetone, urea , derivatives of urea and other complex binders, in which the complexing functional group contains nitrogen phosphorus and sulfur. 10. Galvanic bath according to any of the preceding claims, characterized by the fact that, the catholyte Petition 870180128959, of 9/11/2018, p. 21/27 3/4 contains additional substances chosen from the group consisting of moisturizing gloss media and their mixtures. 11. Galvanic bath according to any of the preceding claims, characterized by the fact that the catholyte has the following composition: 80-250 g / l sodium or potassium hydroxide, 4-20 g / l Zinc in the form of a soluble zinc salt, 0.02-20 g / l Nickel, Iron, Cobalt, Tin in the form of a metal salt soluble as an alloy metal, 1-200 g / l complex builder selected from the group consisting of polyalkeniolamines, alkanolamines, polyhydroxycarboxylates and their mixtures and 0.1-5 g / l aromatic and / or heteroaromatic luster. 12. Galvanic bath according to any of the preceding claims, characterized by the fact that the anolyte consists of 50 to 200 g / l NaOH and 800 to 900 g / l water. 13. Galvanic bath according to claim 1, characterized by the fact that the ion exchange diaphragm is an anion exchange diaphragm. 14. Galvanic bath according to claim 1, characterized by the fact that the second catholyte has a pH in the range of 1 to 7. Galvanic bath according to any one of claims 1 to 14, characterized in that the second catholyte contains sulfuric acid or sulfuric acid or sodium sulfate and / or carboxylic acid and / or its salts. 16. Process for galvanic separation of zinc or zinc alloys in substrates, characterized by the fact that the substrate is introduced into a galvanic bath, as defined in any one Petition 870180128959, of 9/11/2018, p. 22/27 4/4 of the preceding claims, and zinc or zinc alloys are separated from the substrates in a galvanic process. 17. Process according to claim 16, characterized in that the separation takes place at a temperature of 20 to 40 ° C, especially at 25 ° C. 18. Process according to claim 16 or 17, characterized in that the separation takes place at a current density of 0.4 to 5 A / dm ² , especially 0.5 to 3 A / dm ² . 19. Use of a bipolar diaphragm for the separation of anode compartment and cathode compartment in a galvanic bath, characterized by the fact that the galvanic bath has another electrolyte compartment, which is separated by the bipolar diaphragm of the anode compartment, and , by an ion exchange diaphragm from the cathode compartment and a second catholyte. 20. Use of a bipolar diaphragm to prevent the anodic decomposition of organic components of the electrolyte in a galvanic bath, characterized by the fact that the galvanic bath has another electrolyte compartment, which is separated by the bipolar diaphragm of the anode compartment, and, by an ion exchange diaphragm from the cathode compartment and a second catholyte. 21. Use according to either of claims 19 or 20, characterized by the fact that the bipolar diaphragm has at least one cation exchange diaphragm, at least one anion exchange diaphragm and an intermediate layer between the diaphragms, which produces catalyzing the dissociation of water in protons and hydroxide ions. Petition 870180128959, of 9/11/2018, p. 23/27 1/2