Electroplating composition and method for electroplating a chromium film onto a substrate.

Abstract

The present invention relates to an electroplating composition for plating a chromium coating on a substrate, the electroplating composition comprising: (i) a source of hexavalent chromium; (ii) one or more quaternary nitrogen-containing betaines and / or salts thereof; and (iii) one or more polyorganosiloxanes.

Description

[Technical Field]

[0001] This invention relates to electroplating compositions and methods for electroplating a chromium film onto a substrate, as well as the specific use of polyorganosiloxanes to reduce surface tension. This invention is based on synergistic effects. [Background technology]

[0002] Chromium plating has a long history of decorative and functional applications. While it began with hexavalent chromium plating, the development of trivalent chromium plating began in recent decades to replace the environmentally problematic hexavalent chromium species. However, hexavalent chromium plating, which has not yet been replaced by trivalent chromium plating, remains a target for further development and improvement.

[0003] It is well known that hexavalent chromium plating typically results in the formation of undesirable mist and bubbles, and intense gas generation during plating, often due to the use of surfactants (also known as surface-active compounds). Surfactants are usually used not only to reduce surface tension but also to intentionally form bubble blankets to suppress mist. As a result, hexavalent chromium plating compositions often exhibit very low surface tension of approximately 32 mN / m. This usually allows for excellent plating results, even when using substrates with intricate geometric shapes.

[0004] However, the parameters for plating and compositions using hexavalent chromium are demanding due to the use of highly oxidizing chromic acid. Typically, organic compounds decompose rapidly, forming undesirable decomposition products, which dramatically reduces the long-term performance of each electroplating composition. When these decomposition products accumulate, current efficiency usually decreases significantly.

[0005] To overcome this drawback, highly chemically stable organic compounds, such as fully or partially fluorinated surfactants, have been developed. Such organic compounds have been shown to withstand harsh conditions with remarkable efficiency. Furthermore, fluorinated surfactants have proven highly efficient in reducing surface tension.

[0006] A typical drawback of surfactants in general is the excessive formation of bubbles. Therefore, in many cases, defoaming compounds are used in combination with surfactants to limit bubble formation, or in some cases, to eliminate it entirely. However, since defoaming compounds are usually also organic, they suffer from similar problems to surfactants. Furthermore, under harsh plating and compositional parameters, they are subject to rapid decomposition and thus become a major contributor to unwanted degradation products.

[0007] To make the defoaming compounds more chemically resistant, fluorination has also been applied to this group of compounds. Such fluorinated defoaming compounds are disclosed, for example, in German Patent Application Publication No. 3723198. German Patent Application Publication No. 3723198 refers to a perfluorinated defoaming compound for an electroplating composition comprising a surfactant (preferably a fluorinated surfactant). The defoaming compound is disclosed to remove bubbles without impairing the surface tension achieved by the surfactant.

[0008] However, the excellent chemical resistance of such fluorinated organic compounds poses a significant environmental problem because they are not biologically biodegradable. If not properly disposed of, they pose an environmental threat. Therefore, not only the disposal of electroplating compositions but also the treatment of wastewater presents extremely demanding and challenging requirements.

[0009] In the past, attempts have been made to develop, for example, surfactants for hexavalent chromium plating that do not contain fluorine and are thus more environmentally acceptable. For example, U.S. Patent No. 3,432,408 refers to chromium plating electrolytes and methods for preventing their mists. For that purpose, the electrolyte contains a surfactant sulfobetaine that is particularly useful as a hexavalent chromium plating electrolyte.

[0010] Chinese Patent Application Publication No. 111171323 refers to an organosilicon compound as an environmentally friendly fluorine-free mist inhibitor.

[0011] Such surfactant sulfobetaines are more environmentally acceptable, but such compounds often are not sufficiently stable in hexavalent chromium plating compositions and often do not provide the desirable surface tension obtainable with fluorinated surfactants, leaving a problem.

[0012] Therefore, there is still a need to further improve hexavalent chromium compositions.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0014] Object of the Invention Therefore, it is an object of the present invention to provide an electroplating composition that contains a surfactant that does not contain fluorine, but does not impair the current efficiency and surface tension, particularly as compared with commonly used fluorinated surfactants.

[0015] Furthermore, the objective is to prevent the decomposition products from impairing the long-term performance of each electroplating composition. [Means for solving the problem]

[0016] The purpose mentioned above is, (i) Sources of hexavalent chromium; (ii) one or more betaines and / or salts thereof containing quaternary nitrogen; and (iii) One or more polyorganosiloxanes This is solved by an electroplating composition for plating a chromium film onto a substrate, which includes [the specified element].

[0017] Furthermore, the above objectives are achieved by each of the methods of the present invention for electroplating a chromium film onto a substrate.

[0018] Our own experiments have shown that using specific combinations of compounds (ii) and (iii), each preferably as defined throughout this text and designated as most preferred, yields excellent surface tension similar to that achieved with fluorinated surfactants (see Examples below). Most surprisingly, the resulting surface tension is the result of an unexpected synergistic effect between (ii) and (iii). While significantly stronger decomposition of (ii) and (iii) in the electroplating composition is unavoidable, our own experiments have shown that no undesirable decomposition products that impair the long-term performance of the electroplating composition are formed over time. It is presumed that complete decomposition occurs, completely inactivating the decomposition products over time. Although continuous or at least semi-continuous chemical injection is preferably required, the entire method of the present invention can be carried out without the use of any fluorinated organic compounds over the entire service life. Advantageously, compared to the use of fluorinated surfactants, no deterioration in long-term performance is observed over time.

[0019] Furthermore, a significant advantage is that the combination of (ii) and (iii) can be applied to a wide variety of electroplating compositions containing hexavalent chromium sources, i.e., electroplating compositions for functional (also called hard chromium) and decorative applications.

[0020] Typically, functional applications seek chrome coatings that are very hard and wear-resistant, preferably with relatively thick layers (usually up to several hundred micrometers). In contrast, decorative applications have very high demands regarding optical uniformity and are usually relatively thin (typically between 50 nm and 2000 nm). Our own experiments have shown that a combination of (ii) and (iii) can be applied to both applications.

[0021] Therefore, in some cases, the electroplating compositions of the present invention are preferably for plating a functional chromium film. In each case, the chromium film is preferably a functional chromium film, preferably a hard, wear-resistant functional chromium film.

[0022] In other cases, the electroplating composition is preferably for plating a decorative chromium film. In each case, the chromium film is preferably a decorative chromium film.

[0023] Unless otherwise expressly stated, the features relating to the present invention are preferably applied to functional and decorative uses. [Modes for carrying out the invention]

[0024] In the context of the present invention, the terms “at least one,” “one or more,” or “one or more” are interchangeable with “one, two, or three or more” and “one, two, three, or more,” respectively.

[0025] The term "substantially absent" refers to a negligible amount that does not affect the various embodiments of the invention. The term "absent" usually indicates that the total amount of such compounds and components is below the detection range and, most preferably, not present at all.

[0026] (i) Sources of hexavalent chromium: The electroplating composition of the present invention comprises (i) a source of hexavalent chromium. The term "hexavalent chromium" refers to the element chromium having an oxidation state of +6. Its source refers to each compound (including ions) containing this element.

[0027] The electroplating composition of the present invention is preferred in which the source of hexavalent chromium includes chromic acid and / or chromium trioxide, more preferably chromium trioxide solubilized as chromic acid. Most preferably, chromic acid and chromium trioxide are each the sole source of hexavalent chromium.

[0028] The electroplating composition of the present invention is preferred in which the hexavalent chromium source is concentrated in a concentration range of 75 g / L to 480 g / L, preferably 105 g / L to 460 g / L, more preferably 150 g / L to 440 g / L, even more preferably 200 g / L to 420 g / L, and most preferably 225 g / L to 400 g / L, relative to the total volume of the electroplating composition. In the context of the present invention, the concentration of the hexavalent chromium source is preferably based on CrO3. In many cases, the aforementioned concentrations are preferably applied to both functional and decorative applications, preferably to functional applications.

[0029] In some cases, the electroplating composition of the present invention is preferred in which the hexavalent chromium source has a concentration range of 210 g / L to 290 g / L, preferably 220 g / L to 280 g / L, more preferably 230 g / L to 270 g / L, and most preferably 235 g / L to 265 g / L. This is also preferably applicable to both functional and decorative applications.

[0030] However, in several other cases, the electroplating composition of the present invention is preferred, in which the hexavalent chromium source has a concentration range of 281 g / L to 420 g / L, preferably 291 g / L to 400 g / L, more preferably 300 g / L to 390 g / L, even more preferably 320 g / L to 380 g / L, and most preferably 340 g / L to 370 g / L. This is most preferably applied to several decorative applications.

[0031] Preferably, the source of hexavalent chromium is dissolved in water by the formation of an aqueous solution. Therefore, the electroplating composition of the present invention is preferably an aqueous electroplating composition containing more than 50% by volume of water relative to the total volume of the electroplating composition.

[0032] The electroplating composition of the present invention is preferably strongly acidic in pH. This means that the pH is preferably 1 or less, and most preferably 0 or less.

[0033] (ii) One or more betaines containing quaternary nitrogen and / or salts thereof: The electroplating composition of the present invention comprises (ii) one or more betaines and / or salts thereof containing quaternary nitrogen. The quaternary nitrogen is preferably positively charged. Most preferably, the positive charge cannot be removed by proton desorption. This means that the positive charge is stabilized.

[0034] The electroplating composition of the present invention is preferred in which the quaternary nitrogen has substituents such that the positive charge results, provided that the substituents are not hydrogen. Preferably, the substituents include at least an organic residue, preferably an alkyl residue, an ester residue, a carboxyalkyl residue, and / or an amide residue. Preferably, each alkyl residue, ester residue, carboxyalkyl residue, and amide residue contains 1 to 20 carbon atoms.

[0035] Preferably, one or more betaines independently further comprise a sulfonate group and / or a carboxylate group, preferably a sulfonate group. They are preferably negatively charged.

[0036] The electroplating composition of the present invention is preferred in which one or more betaines have a neutral effective charge.

[0037] The electroplating composition of the present invention is preferable in which one or more betaines independently contain at least 5 carbon atoms, preferably at least 7 carbon atoms, more preferably at least 9 carbon atoms, even more preferably at least 11 carbon atoms, even more preferably at least 12 carbon atoms, and most preferably at least 14 carbon atoms. Preferably, one or more betaines have at most 50 carbon atoms.

[0038] The electroplating composition of the present invention is preferable in which one or more of the betaines are amphiphilic. Therefore, the one or more betaines preferably contain at least one (preferably one) hydrophobic moiety. More preferably, the one or more betaines contain both at least one (preferably one) hydrophilic moiety and at least one (preferably one) hydrophobic moiety. Most preferably, the one or more betaines are (not only amphiphilic, but also) surfactant.

[0039] More preferably, the one or more betaines are surfactants and provide a surface tension of 40 mN / m or less, preferably 39 mN / m or less, and more preferably 37 mN / m or less, based on DI water having a surface tension of 70 mN / m or more. Most preferably, this is based on a concentration of 30 mg / L of the one or more betaines. Preferably, the one or more betaines provide a surface tension of at least 36 mN / m.

[0040] The electroplating composition of the present invention is more preferably one in which the one or more betaines are surfactants.

[0041] The electroplating composition of the present invention in which the one or more betaines contain a compound of formula (I) is preferred. (R 1 )N + (R 2 R 3 )-X-Y (I) [wherein, independently R 1 represents alkyl, alkyl ester or alkyl amide, preferably alkyl; R 2 and R 3 represent C1-C5 linear or branched alkyl, preferably C1-C5 linear alkyl; X represents a divalent moiety; Y represents a sulfonic acid group or a carboxylic acid group, preferably a sulfonic acid group].

[0042] R 1 is branched or linear, preferably linear, the electroplating composition of the present invention is preferred.

[0043] R 1 contains 4 to 26 carbon atoms, preferably 6 to 24 carbon atoms, more preferably 8 to 20 carbon atoms, most preferably 12 to 18 carbon atoms, the electroplating composition of the present invention is preferred. Most preferably, R 1 contains 18 carbon atoms.

[0044] R 2 and R 3 independently contain 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms, more preferably 1 or 2 carbon atoms, most preferably 1 carbon atom, the electroplating composition of the present invention is preferred.

[0045] X contains 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, more preferably 2 to 4 carbon atoms, most preferably 3 or 4 carbon atoms, the electroplating composition of the present invention is preferred.

[0046] The electroplating composition of the present invention is preferred in which X represents an alkylene moiety, a hydroxyalkylene moiety, or an alkoxylene moiety, preferably an alkylene moiety. Most preferably, X represents propylene, preferably linear propylene.

[0047] Independent, R 1 This represents a C16-C18 linear alkyl group, preferably a C18 linear alkyl group; R 2 and R 3 This indicates methyl or ethyl, preferably methyl; X represents the C2-C4 alkylene moiety, preferably the C3 alkylene moiety; An electroplating composition of the present invention in which Y represents a sulfonic acid group is preferred.

[0048] A preferred electroplating composition of the present invention is one in which one or more of the betaines are sulfobetaines.

[0049] The one or more betaines mentioned above are at least N,N-dimethyl-N-(3-cocoamidopropyl)-N-(2-hydroxy-3-sulfopropyl)ammonium betaine, N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, N-octyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, N-decyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, and N-dodecyl-N,N-dimethyl A preferred electroplating composition of the present invention comprises one or more (preferably one) of the following: -3-ammonio-1-propanesulfonate, N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, N-octadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, and N,N-dimethyl-N-dodecylglycine betaine.

[0050] The electroplating composition of the present invention is preferable in which one or more of the betaines does not contain phospholipids, and more preferably does not contain phosphorus atoms.

[0051] The electroplating composition of the present invention is preferable in which the one or more betaines have a total concentration of 0.0005 g / L to 1 g / L, preferably 0.001 g / L to 0.5 g / L, more preferably 0.005 g / L to 0.3 g / L, and most preferably 0.01 g / L to 0.2 g / L, relative to the total volume of the electroplating composition.

[0052] An electroplating composition of the present invention is preferred in which one or more of the betaines in the electroplating composition do not contain fluorine atoms. In other words, each of the one or more betaines is not fluorinated and does not contain fluorine.

[0053] (iii) One or more polyorganosiloxanes: The electroplating composition of the present invention comprises (iii) one or more polyorganosiloxanes. In the context of the present invention, (ii) and (iii) are distinct compounds.

[0054] Preferably, one or more polyorganosiloxanes are structurally modified, most preferably in their overall structure.

[0055] Therefore, the electroplating composition of the present invention is preferable in which the polyorganosiloxane is crosslinked, preferably at least two-dimensionally, and most preferably three-dimensionally.

[0056] The electroplating composition of the present invention is preferred in which one or more polyorganosiloxanes are crosslinked via a vinyl portion.

[0057] The electroplating composition of the present invention is preferred in which one or more polyorganosiloxanes are 3D siloxanes, i.e., 3D polyorganosiloxanes. These are available, for example, from Munzing Chemie GmbH.

[0058] An electroplating composition of the present invention in which one or more polyorganosiloxanes are chemically modified is preferred. Most preferably, one or more polyorganosiloxanes are chemically modified to be amphiphilic. Therefore, an electroplating composition of the present invention in which one or more polyorganosiloxanes are amphiphilic is preferred.

[0059] Therefore, one or more polyorganosiloxanes preferably include at least one (preferably repeated) hydrophilic moiety. More preferably, one or more polyorganosiloxanes include both at least one (preferably repeated) hydrophilic moiety and at least one (preferably repeated) hydrophobic moiety.

[0060] The electroplating composition of the present invention is more preferably one in which one or more polyorganosiloxanes are surfactants.

[0061] More preferably, one or more polyorganosiloxanes themselves are less surfactant than the one or more betaines, with reference to water without surfactant compounds, in terms of reducing surface tension.

[0062] Most preferably, one or more polyorganosiloxanes and one or more betaines together are synergistically more surfactantal than each of them individually, with respect to water without surfactant compounds, in terms of reducing surface tension. This is an unexpected effect utilized in the present invention.

[0063] Therefore, one or more polyorganosiloxanes preferably contain a surfactant, and most preferably are surfactants. This means, most preferably, that one or more polyorganosiloxanes are surfactants on their own. More preferably, one or more polyorganosiloxanes are surfactants and provide a surface tension of 60 mN / m or less, preferably 57 mN / m or less, and more preferably 54 mN / m or less, based on DI water having a surface tension of 70 mN / m or more. Most preferably, this is based on a concentration of 30 mg / L of one or more polyorganosiloxanes. Preferably, one or more polyorganosiloxanes provide a surface tension of at least 51 mN / m.

[0064] The electroplating composition of the present invention is preferably further comprising at least one emulsifier. It preferably emulsifies one or more polyorganosiloxanes in the electroplating composition. Therefore, the emulsifier is preferably for emulsifying one or more polyorganosiloxanes in aqueous solution.

[0065] Therefore, an electroplating composition of the present invention is preferred in which one or more of the polyorganosiloxanes are emulsified in the electroplating composition. Preferably, it is an emulsified polyorganosiloxane. Therefore, an electroplating composition of the present invention is preferred in which the electroplating composition comprises an emulsion.

[0066] The electroplating composition preferably contains one or more of the polyorganosiloxanes in a manner in which they are sufficiently finely distributed by an emulsifier, most preferably.

[0067] The electroplating composition of the present invention is preferred in which one or more of the polyorganosiloxanes are homogeneously distributed within the electroplating composition.

[0068] This preferably means that the electroplating composition does not exhibit phase separation, floating interface droplets, interfacial oil film formation, and / or density gradients.

[0069] Typically, when each transmission test is performed, a homogeneous distribution is preferably characterized by homogeneous light transmission through an aqueous solution, preferably an electroplating composition. Those skilled in the art are generally familiar with methods for performing such relatively simple tests.

[0070] The electroplating composition of the present invention is preferable in which the electroplating composition is substantially free of polydimethylsiloxane, preferably free of it, and most preferably substantially free of silicone oil, preferably free of it. Therefore, one or more polyorganosiloxanes are preferably not present, but rather excluded. Our own experiments have shown that in some cases, despite the use of emulsifiers, silicone oil, particularly polydimethylsiloxane, is not sufficiently amphiphilic (and therefore insufficiently surfactant) and / or forms an undesirable heterogeneous distribution including phase separation.

[0071] The electroplating composition of the present invention is preferable in which one or more polyorganosiloxanes are nonionic.

[0072] The electroplating composition of the present invention is preferable in which one or more polyorganosiloxanes have a total concentration of 0.01 mg / L to 5000 mg / L, preferably 0.05 mg / L to 3000 mg / L, more preferably 0.1 mg / L to 1500 mg / L, even more preferably 0.15 mg / L to 1000 mg / L, even more preferably 0.2 mg / L to 500 mg / L, and most preferably 0.25 mg / L to 150 mg / L, relative to the total volume of the electroplating composition.

[0073] The electroplating composition of the present invention is more preferable in which one or more polyorganosiloxanes have a total concentration of 0.01 mg / L to 100 mg / L, preferably 0.05 mg / L to 70 mg / L, more preferably 0.1 mg / L to 50 mg / L, even more preferably 0.15 mg / L to 25 mg / L, even more preferably 0.2 mg / L to 10 mg / L, and most preferably 0.3 mg / L to 5 mg / L, relative to the total volume of the electroplating composition.

[0074] The electroplating composition of the present invention is preferable in which one or more polyorganosiloxanes contain a total amount of silicon in the range of 15% to 40% by mass, preferably 20% to 30% by mass, relative to the total mass of the one or more polyorganosiloxanes.

[0075] The aforementioned preferred and more preferred options are preferably applicable to both functional and decorative uses.

[0076] The electroplating composition of the present invention is preferred in which one or more polyorganosiloxanes contain one or more vinyl moieties. The method of the present invention is more preferred in which one or more polyorganosiloxanes contain at least one vinyl moiety containing an unsaturated double bond, but the other vinyl moieties are involved in crosslinking in such a way that their double bonds are no longer present. This preferably means that the polyorganosiloxanes used in the method of the present invention are partially crosslinked via vinyl moieties in which not all vinyl moieties are used for crosslinking.

[0077] The electroplating composition of the present invention is preferably composed of one or more polyorganosiloxanes, which include carbon atoms, hydrogen atoms, silicon atoms, and oxygen atoms.

[0078] The electroplating composition of the present invention is preferable in which one or more polyorganosiloxanes do not contain nitrogen atoms.

[0079] The electroplating composition of the present invention is preferable in which one or more polyorganosiloxanes do not contain sulfur atoms.

[0080] In the electroplating composition, the electroplating composition of the present invention is preferred in which one or more polyorganosiloxanes do not contain fluorine atoms. In other words, the one or more polyorganosiloxanes are not fluorinated.

[0081] The electroplating composition of the present invention is preferable in which the composition contains cyclotetrasiloxane (D4), cyclopentasiloxane (D5), and cyclohexasiloxane (D6) at a total concentration of 0.1% by mass or less relative to the total mass of the electroplating composition.

[0082] More preferably, the electroplating composition of the present invention is substantially free of cyclotetrasiloxane (D4), cyclopentasiloxane (D5), and cyclohexasiloxane (D6).

[0083] Further characteristics of the electroplating composition: In the electroplating composition of the present invention, trivalent chromium ions are not intentionally added. Most preferably, the electroplating composition is substantially free of trivalent chromium ions, and preferably, it is free of them.

[0084] Based on measurements with a tension meter, the electroplated composition of the present invention is preferred to have a surface tension of 50 mN / m or less, preferably 45 mN / m or less, more preferably 40 mN / m or less, even more preferably 38 mN / m or less, still more preferably 36 mN / m or less, and most preferably 35 mN / m or less. In some cases, it is most preferably 34 mN / m or less or 33 mN / m or less. In the context of the present invention, it is most preferable to use a Wilhelmy plate as the tension meter to determine the surface tension.

[0085] Based on measurements using a tension meter, the electroplating composition of the present invention is more preferable if it has a surface tension in the range of 28 mN / m to 40 mN / m, preferably 30 mN / m to 38 mN / m, and most preferably 31 mN / m to 36 mN / m.

[0086] This is the desirable effect obtained from the combination of (ii) and (iii). Our own experiments have shown that the combination not only has a synergistic effect, but also allows for a reduced total concentration of the surfactant compound in several cases (compare Example C3 and Example 1).

[0087] (iv) The electroplating composition of the present invention further contains sulfate ions, which is preferable.

[0088] The electroplating composition of the present invention is preferable in which sulfuric acid is the source of sulfate ions. Sulfuric acid has excellent properties for dissolving chromium trioxide.

[0089] The electroplating composition of the present invention is preferable in which sulfate ions have a concentration in the range of 0.1 g / L to 10 g / L, preferably 1 g / L to 8.5 g / L, more preferably 1.5 g / L to 7.5 g / L, even more preferably 2 g / L to 6.5 g / L, and most preferably 3 g / L to 5 g / L, relative to the total volume of the electroplating composition.

[0090] In some cases, the electroplating composition of the present invention is preferred in which sulfate ions are concentrated in the range of 0.1 g / L to 8 g / L, preferably 0.3 g / L to 7 g / L, more preferably 0.5 g / L to 6 g / L, even more preferably 0.7 g / L to 5 g / L, and most preferably 1 g / L to 4 g / L, relative to the total volume of the electroplating composition. This is most preferably applied to decorative applications.

[0091] (v) The electroplating composition of the present invention is preferably further comprising one or more sulfonic acids and / or salts thereof containing two or more sulfonic acid groups, preferably one or more alkyl sulfonic acids and / or salts thereof containing two or more sulfonic acid groups.

[0092] This is most preferably applied to functional applications and is highly desirable for obtaining and maintaining relatively high current densities.

[0093] The electroplating composition of the present invention is preferred in which the electroplating composition comprises one or more alkane disulfonic acids and / or salts thereof, preferably methane disulfonic acid and / or salts thereof. These are very preferred sulfonic acids and / or salts thereof, which contain two sulfonic acid groups. This is most preferably applied to functional applications.

[0094] The electroplating composition of the present invention is preferable in which one or more alkane disulfonic acids and their salts have a total concentration in the range of 0.5 g / L to 15 g / L, preferably 1 g / L to 12 g / L, and more preferably 1.5 g / L to 10 g / L, relative to the total volume of the electroplating composition. This is most preferably applied to functional applications.

[0095] The electroplating composition of the present invention is preferred in which the electroplating composition comprises one or more alkanetrisulfonic acids and / or salts thereof, preferably methanetrisulfonic acid and / or salts thereof. These are very preferred sulfonic acids and / or salts thereof, which contain three sulfonic acid groups. This is most preferably applied to functional applications.

[0096] The electroplating composition of the present invention is preferable in which one or more alkane trisulfonic acids and their salts have a total concentration in the range of 0.1 g / L to 13 g / L, preferably 0.5 g / L to 10 g / L, and more preferably 1 g / L to 7 g / L, relative to the total volume of the electroplating composition. This is most preferably applied to functional applications.

[0097] Furthermore, (vi) an electroplating composition according to the present invention that may contain silver ions, and preferably contains silver ions, is preferred.

[0098] The presence of silver ions is preferable for functional applications, but preferably not for decorative applications. Silver ions preferably reduce the risk of forming too many trivalent chromium ions.

[0099] The electroplating composition of the present invention is preferable in which the total concentration of silver ions is in the range of 0.0001 g / L to 3 g / L, preferably 0.001 g / L to 1 g / L, and most preferably 0.01 g / L to 0.3 g / L, relative to the total volume of the electroplating composition. This is most preferably applied to functional applications.

[0100] The electroplating composition of the present invention is preferably substantially free of methanesulfonic acid and its salts, preferably substantially free of alkylmonosulfonic acid and its salts, preferably substantially free of monosulfonic acid and its salts. This is most preferably applicable to both functional and decorative applications.

[0101] The electroplating composition of the present invention is preferably substantially free of alkyl sulfonic acid and its salts, preferably substantially free of sulfonic acid and its salts, preferably free of them. This is most preferably applied to decorative applications.

[0102] The present invention completely avoids the use of any fluorinated surfactants and makes it possible to achieve a surface tension close to or even the same as that obtained with fluorinated surfactants. This is a great benefit of the present invention. The electroplating composition of the present invention is preferable in which the electroplating composition is substantially free of fluorinated surfactants, preferably not, and most preferably substantially free of fluorinated organic compounds. Furthermore, the long-term performance of the electroplating composition is not impaired (see the examples below).

[0103] However, this does not preclude the use of inorganic fluorine compounds such as fluoride anions, which do not pose a significant problem. Therefore, an electroplating composition of the present invention further comprising fluoride anions is preferred. This is most preferably applied to decorative applications.

[0104] The electroplating composition of the present invention is preferably one that further comprises a fluorine-containing inorganic compound, preferably a fluorosilicate, and most preferably SiF6. This is most preferably applied to decorative applications to increase the gloss and uniformity of the chromium film and thus improve the optical appearance.

[0105] The electroplating composition of the present invention is preferred in which a fluorine-containing inorganic compound (preferably a fluorosilicate, most preferably SiF6) has a total concentration in the range of 0.2 g / L to 2 g / L relative to the total volume of the electroplating composition. As mentioned, this is most preferably applied to decorative applications.

[0106] Electroplating methods: The present invention further relates to a method for electroplating a chromium film onto a substrate, and the method is as follows: (a) The process of preparing the base, (b) A step of providing an electroplating composition according to the present invention, preferably as described, into an electroplating section. (c) A step of bringing the substrate into contact with the electroplating composition within the electroplating section and applying an electric current so that a chromium film is electroplated on at least one surface of the substrate. Includes.

[0107] Preferably, the aforementioned features relating to the electroplating composition of the present invention also apply to the method of the present invention, most preferably to step (b) of the method.

[0108] In step (a), the method of the present invention is preferred in which the substrate includes a metallic substrate and / or a plastic substrate. Metallic substrates are generally preferred in functional applications as well as decorative applications. Plastic substrates are generally preferred in decorative applications. Preferred metallic substrates include iron, copper and / or zinc. Very preferred metallic substrates include steel or brass, and most preferably steel rods. Preferred plastic substrates include ABS, PA and / or ABS-PC.

[0109] The method of the present invention is preferred in which, in step (c), the electroplating section preferably includes at least one anode selected from the group consisting of a lead-containing anode, a noble metal-containing anode, and mixed metal oxide anode, and most preferably in which the electroplating section in step (c) includes at least one lead-containing anode.

[0110] In step (c), the method of the present invention is preferable in which the lead-containing anode contains more than 50% by mass, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more, of the total mass of the lead-containing anode.

[0111] In step (c), the method of the present invention is preferable in which the lead-containing anode is selected from the group consisting of lead-tin anodes and lead-antimony anodes.

[0112] In step (c), the method of the present invention is preferable in which the anode containing a precious metal also contains a titanium anode coated with platinum.

[0113] In step (c), the method of the present invention is preferable in which the chromium film has a thickness in the range of 0.05 μm to 1000 μm, preferably 1 μm to 800 μm, more preferably 2.1 μm to 600 μm, even more preferably 3 μm to 400 μm, still even more preferably 4 μm to 300 μm, and most preferably 5 μm to 250 μm. This is most preferably, and most preferably, starting from 2.1 μm, and is applicable to functional applications.

[0114] In step (c), the method of the present invention is preferable in which the chromium film has a thickness in the range of 0.05 μm to 10 μm, preferably 0.06 μm to 8 μm, more preferably 0.07 μm to 6 μm, even more preferably 0.08 μm to 4 μm, still more preferably 0.09 μm to 3 μm, and most preferably 0.1 μm to 2 μm. This is most preferably applied to decorative applications.

[0115] In step (c), the current is at least 18 A / dm 2 Preferably at least 25 A / dm 2 , more preferably at least 30 A / dm 2 More preferably, at least 40 A / dm 2 Most preferably at least 50 A / dm 2 The method of the present invention having a cathode current density of 18 A / dm² is preferred. Preferably, the cathode current density is 18 A / dm². 2~260A / dm 2 More preferably 25 A / dm 2 ~200A / dm 2 , most preferably 35 A / dm 2 ~100A / dm 2 It falls within this range. This is most preferably applied to functional uses.

[0116] In step (c), the current is at least 1 A / dm 2 Preferably at least 3 A / dm 2 , more preferably at least 5 A / dm 2 More preferably, at least 7 A / dm 2 , most preferably at least 9 A / dm 2 A method of the present invention having a cathode current density of 1 A / dm² is preferred. Preferably, the cathode current density is 1 A / dm². 2 ~20A / dm 2 , more comfortable 3A / dm 2 ~18A / dm 2 More preferably 4A / dm 2 ~17A / dm 2 , most preferably 5A / dm 2 ~15A / dm 2 It falls within this range. This is most preferably applied to decorative purposes.

[0117] Preferably, in step (c), the current is direct current.

[0118] In step (c) within the electroplating section, the method of the present invention is preferred in which more than 50% of the surface of the electroplating composition is covered with a foam layer having a thickness of preferably 0.5 cm to 3 cm. This is preferably applicable to both functional and decorative applications. The combination of (ii) and (iii) in the present invention not only provides a foam layer for excellent coverage against mist, but also results in improved foam density.

[0119] In step (c) within the electroplating section, the method of the present invention is preferred such that more than 60%, preferably more than 70%, more preferably more than 80%, even more preferably more than 90%, and most preferably more than 95% of the surface of the electroplating composition is covered with a foam layer, and most preferably the entire surface of the electroplating composition is covered with a foam layer. Most preferably, this is applied to a foam layer with a preferred thickness in the range of 0.5 cm to 3 cm. This is preferably applied to both functional and decorative applications.

[0120] In step (c), the method of the present invention is preferable in which the electroplating composition has a temperature in the range of 20°C to 90°C, preferably 30°C to 70°C, more preferably 40°C to 60°C, and most preferably 45°C to 58°C. This is most preferably applied to functional applications.

[0121] In other cases, the method of the present invention is preferred in which, in step (c), the electroplating composition has a temperature in the range of 20°C to 70°C, preferably 25°C to 60°C, more preferably 30°C to 60°C, and most preferably 35°C to 50°C. This is most preferably applied to decorative applications.

[0122] The method of the present invention is preferable in which step (c) is carried out for a period of 1 to 200 minutes, preferably 2 to 100 minutes, and more preferably 3 to 60 minutes. This is preferably applicable to both functional and decorative applications.

[0123] However, in some cases, the method of the present invention is preferred in which step (c) is carried out for a period of 1 to 15 minutes, preferably 1.5 to 12 minutes, and more preferably 2 to 10 minutes. This is preferably applied to decorative applications.

[0124] In other cases, the method of the present invention is preferred in which step (c) is carried out for a period of 5 to 180 minutes, preferably 10 to 100 minutes, and more preferably 11 to 60 minutes. This is preferably applied to functional applications.

[0125] By carrying out method step (c) within the preferred temperature range and / or (preferably and) preferred period described above, a particularly advantageous electrodeposition reaction kinetics during step (c) can be ensured.

[0126] In some cases, after step (c), Step (d) involves heat-treating the chromium coating base obtained from step (c). A method of the present invention further comprising the above is preferred.

[0127] This is preferably applied to functional applications.

[0128] In step (d), the heat treatment is preferably carried out at a temperature in the range of 100°C to 250°C, preferably 120°C to 240°C, more preferably 150°C to 220°C, and most preferably 170°C to 200°C, according to the method of the present invention.

[0129] In step (d), the heat treatment is preferably carried out for a period of 1 to 10 hours, more preferably 2 to 4 hours, according to the method of the present invention.

[0130] Preferably, the properties of the chromium coating can be further improved (e.g., by reducing hydrogen embrittlement) by performing a heat treatment in step (d) at a more preferred temperature and / or for a preferred period of time.

[0131] In step (c), the method of the present invention is preferable in which the cathode current efficiency (CCE) is in the range of 20% to 30%, more preferably 22% to 27%. This is most preferably applied to functional applications.

[0132] The present invention further relates to the use of polyorganosiloxanes in electroplating compositions for reducing surface tension, preferably in combination with one or more betaines and / or salts thereof containing quaternary nitrogen, in an electroplating composition for plating chromium films from hexavalent chromium, most preferably in an electroplating composition.

[0133] In addition to the methods of the present invention, the foregoing relating to the electroplating compositions of the present invention is preferably also applicable to the use of the present invention.

[0134] The present invention is described in more detail by the following non-limiting embodiments. [Examples]

[0135] For all of the following examples, the following base electroplating composition was used: (i) Chromic acid, 250 g / L; (ii) N-octadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, at various concentrations; (iii) Emulsified and homogeneously distributed 3D polyorganosiloxane (i.e., 3D siloxane from Munzing Chemie GmbH); at various concentrations; (iv) Sulfate ions, 2-5 g / L (added as sulfuric acid); (v) Methandesulfonic acid (1.5~10 g / L); pH is strongly acidic.

[0136] Experiment Group 1 (Surface Tension): In the first set of experiments, various concentrations of (ii) and (iii) were tested, as summarized in Table 1 below. For all experiments, surface tension was determined, and test plating was performed only for promising combinations. Promising means that a desired thickness of up to 3 cm of foam coating was obtained, along with the desired foam structure and appropriate bubble size (improved foam density).

[0137] Surface tension (ST) was measured using a tension meter with a Wilhelmy plate (DCAT 9, Dataphysics) manufactured from Pt-Ir.

[0138] [Table 1]

[0139] Since only (ii) or (iii) is present in the electroplating composition, C1 to C7 represent comparative examples. For comparison, using commonly used fluorinated surfactants, surface tensions in the range of 28 to 32 mN / m are typically obtained (data not shown).

[0140] Furthermore, in each case, C2-C4 showed excessive bubble formation, while C5-C7 showed no foaming at all, but this is unacceptable as it also fails to suppress mist.

[0141] In contrast, experiments 1-23 are examples of the present invention that include both (ii) and (iii).

[0142] As shown in Table 1, all comparative examples demonstrate that each individual compound, namely (ii) alone and (iii) alone, cannot reach the surface tension obtained with the combination of (ii) and (iii). Interestingly, (iii) alone results in only a moderate decrease in surface tension (see C6, 52 mN / m), while (ii) alone already results in a significant decrease in surface tension (see C3 and C4, 37 mN / m). This indicates that (ii) alone has a significant potential to reduce the surface tension of the electroplated composition.

[0143] However, as is also evident in Table 1, the combination of (ii) and (iii) further reduces the surface tension (see Nos. 1-10). This is quite surprising, as the resulting surface tension is lower than what would be expected from (ii) and (iii) alone. Therefore, (iii) clearly further enhances the reduced surface tension. In this sense, (iii) synergistically supports the effect of (ii) in an unexpected way.

[0144] This synergistic effect can be seen even more clearly in experiments 16-23, where (ii) is constant at 30 mg / L and (iii) varies from 3.2 to 8.8 mg / L. Increasing the concentration of (iii) results in an even lower surface tension. Similar surface tensions were obtained in Nos. 9 and 10, but Nos. 21-23 show that the presence of (iii) essentially contributes to the excellent surface tensions of approximately 30 and 31 mN / m, respectively.

[0145] In all experiments, fluorinated organic compounds were not used. However, similarly good, or even the same, surface tension was obtained using fluorine-free organic compounds compared to commonly used fluorinated organic compounds.

[0146] In further comparative examples, emulsified polydimethylsiloxane was used instead of 3D siloxane at two concentrations (0 mg / L, 2.4 mg / L, and 4.8 mg / L as controls). In these examples, 30 mg / L of (ii) was present. However, an overall surface tension of 38 mN / m was obtained in each case. Furthermore, polydimethylsiloxane alone did not contribute to the reduction of surface tension. Therefore, the presence of polydimethylsiloxane does not result in a synergistic effect when combined with betaine.

[0147] This effect has been confirmed and is applicable to functional applications as well as decorative ones (the electroplating results for decorative applications are not specifically shown).

[0148] Experiment Group 2 (Long-term performance): In the second set of experiments, the long-term performance of the electroplating composition of the present invention was investigated. Generally, the cathode current efficiency (CCE) determined over time is recognized as an important indicator of whether the performance of the composition can be considered stable. Normally, if decomposition products accumulate over time, the CCE decreases significantly, which is undesirable. Since chromic acid-based electroplating compositions are subjected to a strongly acidic and oxidizing chemical environment, the formation of decomposition products from non-fluorinated compounds is unavoidable. The cathode current efficiency in % was calculated according to Faraday's law and mass spectrometry.

[0149] Therefore, CCE was determined for three different quantities (900 ml = A, 2 L = B, and 110 L = C). Accordingly, three different plating section geometric shapes were also used. 900 ml and 2 L were tested in beakers, while 110 L was tested in a suitable plating tank. It is noteworthy that in each case, different ratios were obtained between the amount of electroplated composition and the surface area of ​​the electroplated composition. Our own experiments showed that, depending on such ratios, different combinations of (ii) and (iii) are considered advantageous considering the foam layer thickness and foam layer coverage.

[0150] As summarized in Table 2, the following convenient combinations of (ii) and (iii) were tested.

[0151] [Table 2]

[0152] The CCE was determined by test electroplating using the following parameters: Temperature: 55℃; Cathode current density: 50A / dm 2 ; Anode: PbSn

[0153] Test electroplating was performed at a maximum of 1044 Ah / L (in Table 3, "Age" represents Ah / L). Compounds (ii) and (iii) were replenished based on visual inspection of the foam layer that should completely cover the surface during the test electroplating; however, there was no foam accumulation in the corners and near the tank walls.

[0154] A mild steel rod with a diameter of 10 mm was used as the base material. Before electroplating, the base material was pre-treated by degreasing with acetone.

[0155] After the test electroplating, no undesirable optical defects were found during visual inspection of the chromium coating.

[0156] The cathode current efficiency (CCE) in percentage was calculated according to Faraday's law and mass spectrometry.

[0157] The following results were obtained, as summarized in Table 3.

[0158] [Table 3]

[0159] Typically, the CCE (carbon cation exchange) of conventional electroplating compositions containing fluorinated organic compounds is approximately 25% over time.

[0160] Table 3 clearly shows that CCE remained relatively constant in A, B, and C; no significant decrease was observed. These results confirm the stable long-term performance of the electroplating composition. Although decomposition products are presumed to be formed, they did not accumulate over the test period; therefore, it can be concluded that there is no significant accumulation of harmful decomposition products over even longer periods. Rather, it is presumed that even the decomposition products decompose significantly and therefore do not accumulate.

[0161] Furthermore, Table 3 shows that the CCE is not only constant but also remains within the range of approximately 25% in absolute terms. This is an excellent result, as 25% can be obtained even when fluorinated organic compounds are used in conventional electroplating compositions. Therefore, the combination of (ii) and (iii) does not negatively affect the current efficiency, even during long-term application.

[0162] In particular, we conducted a second set of experiments on functional electroplating.

Claims

1. An electroplating composition for plating a chromium film onto a substrate, (i) Sources of hexavalent chromium; (ii) one or more betaines and / or salts thereof containing quaternary nitrogen; and (iii) Containing one or more polyorganosiloxanes An electroplating composition, The one or more of the above betaines are defined by formula (I) (R 1 )N + (R 2 R 3 )-X-Y (I) [In the formula, independently R1 represents a linear alkyl group of C16 to C18. R2 and R3 represent methyl or ethyl. X represents the C2-C4 alkylene portion. [Y indicates a sulfonic acid group] Contains the compound, The aforementioned polyorganosiloxane is an electroplating composition comprising a 3D polyorganosiloxane.

2. The electroplating composition according to claim 1, wherein the betaine is N-octadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate.

3. The electroplating composition according to claim 1 or 2, wherein the polyorganosiloxane is crosslinked.

4. The electroplating composition according to any one of claims 1 to 3, wherein the one or more polyorganosiloxanes are amphiphilic.

5. The electroplating composition according to any one of claims 1 to 4, wherein one or more of the polyorganosiloxanes are surfactants.

6. The electroplating composition according to any one of claims 1 to 5, wherein one or more of the polyorganosiloxanes are emulsified in the electroplating composition.

7. The electroplating composition according to any one of claims 1 to 6, wherein the one or more polyorganosiloxanes are homogeneously distributed in the electroplating composition.

8. An electroplating composition according to any one of claims 1 to 7, which is substantially free of polydimethylsiloxane.

9. An electroplating composition according to any one of claims 1 to 8, having a surface tension of 50 mN / m or less based on measurements using a tension meter.

10. An electroplating composition according to any one of claims 1 to 9, which is substantially free of methanesulfonic acid and its salts.

11. A method of electroplating a chromium film onto a substrate, (a) The process of preparing the base, (b) A step of providing the electroplating composition according to any one of claims 1 to 10 into an electroplating section. (c) A step of bringing the substrate into contact with the electroplating composition within the electroplating section and applying an electric current so that the chromium film is electroplated on at least one surface of the substrate. Methods that include...

12. The method according to claim 11, wherein in step (c), the electroplating section includes at least one anode selected from the group consisting of a lead-containing anode, a precious metal-containing anode, and a mixed metal oxide anode.

13. The method according to any one of claims 11 or 12, wherein in step (c), more than 50% of the surface of the electroplating composition within the electroplating section is covered with a foam layer having a thickness in the range of 0.5 cm to 3 cm.

14. The use of betaine and / or its salt and polyorganosiloxane in an electroplating composition for reducing surface tension, The aforementioned betaine is given by formula (I) (R 1 )N + (R 2 R 3 )-X-Y (I) [In the formula, independently R1 represents a linear alkyl group of C16 to C18. R2 and R3 represent methyl or ethyl. X represents the C2-C4 alkylene portion. [Y indicates a sulfonic acid group] Contains the compound, The aforementioned polyorganosiloxane includes 3D polyorganosiloxane.

15. The use according to claim 14, wherein the betaine is N-octadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate.

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