Flux liquid for hot-dip plating and hot-dip plating method

Abstract

To provide a flux solution for hot dipping which does not contain hydrochloric acid as a main acid and in which metal plating for coating the surface of a plating object has high wettability, and to provide a hot dipping method capable of satisfactorily coating the surface of the plating object with metal plating while suppressing or preventing hydrogen chloride from vaporizing and remaining in a surrounding atmosphere.SOLUTION: The hot dipping method includes: a flux step S1 in which the surfaces of the wire rod are flux-treated using a flux solution for hot dipping; and a hot dipping step S2 in which the wire rod after the flux step S1 is immersed in a plating tank and then pulled up from the plating tank, and the surfaces of the wire rod are coated with metal plating. The flux solution for hot dipping used in the flux step S1 contains carboxylic acid, a surfactant, and at least one of zinc chloride and ammonium chloride.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a flux liquid for hot dip plating and a hot dip plating method. [Background technology]

[0002] Hot-dip galvanization has been known as a method for coating the surface of a plating object, such as a wire rod, with a metal plating. In the hot-dip galvanization, the plating object (e.g., a wire rod) is immersed in a plating tank containing molten metal. Then, the plating object is pulled out of the plating tank, whereby the surface of the plating object is coated with a metal plating.

[0003] In the hot-dip plating method, as shown in Patent Document 1 below, the surface of the object to be plated is sometimes fluxed with a hot-dip plating flux solution before the object is immersed in a plating tank in order to achieve good metal plating coverage. Various flux solutions can be used as the hot-dip plating flux solution. Patent Document 2 below discloses Azonyl as a flux solution. Azonyl is a strong acid containing hydrochloric acid, and in addition to hydrochloric acid, also contains ammonium chloride and zinc chloride. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 60-243257 [Patent Document 2] Japanese Patent Publication No. 12859 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when Azonyl is used as a flux liquid for hot-dip plating, the following problems arise: The flux liquid adheres to the surface of the object to be plated when immersed in molten metal. When immersed in molten metal, the flux liquid is vaporized by the high temperature of the molten metal. Because Azonyl contains hydrochloric acid as its main acid, when Azonyl is used as a flux liquid for hot-dip plating, hydrogen chloride (HCl) may remain in the surrounding atmosphere. If hydrogen chloride (HCl) remains in the surrounding atmosphere, it may lead to oxidation or chlorination of equipment and structures (i.e., rust formation) and / or deterioration of the production environment.

[0006] Therefore, there is a need for a new flux treatment solution for hot dip plating that can replace Azonyl. This flux treatment solution is required not only to not contain hydrochloric acid as the main acid, but also to have high wettability for the metal used to plate the object to be plated.

[0007] Therefore, one object of the present invention is to provide a flux solution for hot dip plating which does not contain hydrochloric acid as a main acid and which provides high wettability to the metal plating that coats the surface of an object to be plated.

[0008] Another object of the present invention is to provide a hot-dip galvanizing method that can satisfactorily coat the surface of an object to be plated with a metal plating while suppressing or preventing hydrogen chloride from vaporizing and remaining in the surrounding atmosphere. [Means for solving the problem]

[0009] One embodiment of the present invention provides a flux liquid for hot dip plating having the following characteristics.

[0010] 1. A flux solution for hot dip plating, comprising a carboxylic acid, a surfactant, and at least one of zinc chloride and ammonium chloride.

[0011] According to the present invention, it is possible to provide a flux solution for hot dip plating which does not contain hydrochloric acid as a main acid and which provides high wettability to the metal plating that coats the surface of the object to be plated.

[0012] 2. The flux solution for hot dip plating according to item 1, wherein the carboxylic acid includes a hydroxy acid.

[0013] 3. The flux solution for hot dip plating according to Item 2, wherein the hydroxy acid includes at least one of malic acid and citric acid.

[0014] 4. The flux solution for hot dip plating according to any one of items 1 to 3, wherein the carboxylic acid includes at least one of acetic acid, malonic acid, maleic acid, butyric acid, and propanoic acid.

[0015] 5. The flux liquid for hot dip plating according to any one of items 1 to 4, wherein the carboxylic acid includes a plurality of carboxylic acids different from each other.

[0016] 6. The flux liquid for hot dip plating according to any one of items 1 to 5, wherein the surfactant includes an acetylene-based nonionic surfactant.

[0017] 7. A fluxing process of fluxing the surface of the object to be plated using a flux liquid for hot dip plating; a hot-dip plating step of immersing the object to be plated after the flux step in a plating tank and then lifting it out of the plating tank to coat the surface of the object to be plated with a metal plating, The hot-dip plating method, wherein the hot-dip plating flux liquid used in the fluxing step contains a carboxylic acid, a surfactant, and at least one of zinc chloride and ammonium chloride.

[0018] According to the present invention, since the flux liquid for hot dip plating does not contain hydrochloric acid as a main acid, it is possible to suppress or prevent the generation of hydrogen chloride (HCl) in the surroundings during the hot dip plating process, thereby reducing or eliminating the effects of hydrogen chloride remaining in the surrounding atmosphere as a vapor.

[0019] Furthermore, since the surface of the object to be plated is fluxed using the flux solution for hot dip plating, the metal plating that coats the surface of the object to be plated has high wettability, which allows the surface of the object to be well coated with the metal plating.

[0020] Therefore, it is possible to provide a hot-dip plating method that can satisfactorily coat the surface of an object to be plated with a metal plating while suppressing or preventing hydrogen chloride from vaporizing and remaining in the surrounding atmosphere. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram for explaining a hot dip plating apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow chart showing the flow of the hot dip plating method according to one embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing the test results of the wettability test for the invention examples and the comparative examples. [Figure 4] FIG. 4 is a diagram showing the test results of the wettability test for the invention examples and the comparative examples. [Figure 5] FIG. 5 is a diagram showing the test results of the wettability test for the invention examples and the comparative examples. [Figure 6] FIG. 6 is a graph showing the test results of the wettability test for an example of the present invention (Test No. T12). [Figure 7] FIG. 7 is a graph showing the test results of the wettability test for the comparative example (test number T0). [Figure 8] FIG. 8 is a diagram showing the hydrogen chloride concentrations in an example of the present invention (test number T12) and a comparative example (test number T0). DETAILED DESCRIPTION OF THE INVENTION

[0022] A hot-dip galvanizing method according to an embodiment of the present invention will be described in detail below with reference to the drawings. In addition, a hot-dip galvanizing flux liquid 1 according to an embodiment of the present invention will be described in detail.

[0023] Fig. 1 is a schematic diagram for explaining a hot-dip galvanizing apparatus 2 according to one embodiment of the present invention. Fig. 2 is a flow chart showing the flow of a hot-dip galvanizing method according to one embodiment of the present invention.

[0024] The hot-dip coating apparatus 2 performs a fluxing step S1 and a hot-dip coating step S2 on a wire 3 as an example of an object to be coated. The hot-dip coating apparatus 2 includes a wire supply section 4, a flux tank 5, a coating tank 6, a wire recovery section 7, and a plurality of guide rollers 8. The hot-dip coating method shown in FIG. 2 is performed in the hot-dip coating apparatus 2.

[0025] The wire supply unit 4 is equipped with a supply bobbin 9. A wire 3 is wound around the supply bobbin 9. The wire 3 is a round wire with a circular cross section. In this embodiment, the wire 3 is a copper wire. The wire 3 may be an iron wire (steel wire). The wire 3 wound around the supply bobbin 9 is a wire after wire drawing. The wire diameter (diameter) of the wire 3 is preferably 0.05 mm or more and 2.0 mm or less. The wire diameter is more preferably 0.1 mm or more and 1.0 mm or less.

[0026] The flux tank 5 stores a flux liquid 1 for hot dip plating. The flux liquid 1 for hot dip plating has cleaning, anti-oxidation, and surface tension reducing effects. The cleaning effect is to remove foreign matter and oxide films from the wire 3. The anti-oxidation effect is to prevent oxidation of the surface of the wire 3. The surface tension reducing effect is to improve the surface wettability of the wire 3, making it easier for the flux liquid to spread. The temperature of the flux liquid stored in the flux tank 5 is not particularly limited. The temperature of the flux liquid may be room temperature (25°C).

[0027] Molten metal is stored in the plating tank 6. In this embodiment, the molten metal is tin (Sn). That is, molten tin is stored in the plating tank 6. In other words, the plating tank 6 receives a plating bath of tin. The temperature of the stored molten tin is 230°C or higher and 300°C or lower.

[0028] The wire recovery section 7 is provided with a take-up bobbin 10. The take-up bobbin 10 is wound with the wire 3 whose surface is coated with tin plating (that is, a tin-plated wire).

[0029] The plurality of guide rollers 8 include sinker rollers 11 and pull-up rollers 12. The sinker rollers 11 are disposed in the molten tin in the coating tank 6. The sinker rollers 11 guide the wire 3 passing through the molten tin in the coating tank 6. The pull-up rollers 12 are disposed above the sinker rollers 11. The pull-up rollers 12 are disposed at a predetermined interval above the liquid surface (melt surface) of the molten tin in the coating tank 6.

[0030] 1 and 2, a hot-dip galvanizing method using a hot-dip galvanizing apparatus 2 will be described. A wire 3 drawn out from a supply bobbin 9 of a wire supply unit 4 is sent to a flux tank 5. The wire 3 passes through a flux liquid 1 for hot-dip galvanizing stored in the flux tank 5.

[0031] Specifically, the wire 3 is immersed in the flux liquid 1 for hot dip plating and then pulled out. This causes the surface of the wire 3 to be flux-treated (S1 in FIG. 2: fluxing step). The fluxing removes foreign matter and oxide films from the wire 3 (cleaning), prevents oxidation of the surface of the wire 3 (antioxidation), and improves the surface wettability of the wire 3 (reducing surface tension).

[0032] In the fluxing step S1, the wire speed of the wire 3 is preferably 10 m / min or more and 800 m / min or less, and more preferably 50 m / min or more and 100 m / min or less.

[0033] The wire 3 that has passed through the hot-dip plating flux liquid 1 is sent to the plating tank 6 by the guide rollers 8. The wire 3 is immersed in molten tin and then pulled up. The wire 3 pulled up from the molten tin is air-cooled before being wound around the pull-up rollers 12. This forms a plating layer on the surface of the wire 3 (S2 in FIG. 2: hot-dip plating step). In other words, the surface of the wire 3 is covered with tin plating (metal plating). This produces a tin-plated wire.

[0034] In the hot dip coating step S2, the wire speed of the wire 3 is preferably 10 m / min or more and 800 m / min or less, and more preferably 50 m / min or more and 100 m / min or less.

[0035] The produced tin-plated wire is wound around a take-up bobbin 10 and collected in the wire recovery section 7.

[0036] The hot-dip galvanizing flux liquid 1 stored in the flux tank 5 contains a carboxylic acid, a surfactant, and at least one of zinc chloride (ZnCl) and ammonium chloride (NHCl). In this embodiment, both zinc chloride and ammonium chloride are contained in the hot-dip galvanizing flux liquid 1. The hot-dip galvanizing flux liquid 1 may contain only one of zinc chloride and ammonium chloride.

[0037] The carboxylic acid includes a hydroxy acid. The hydroxy acid may be malic acid (C4H6O5). The hydroxy acid may be citric acid (C6H8O7).

[0038] The hot-dip galvanizing flux liquid 1 may contain a carboxylic acid other than a hydroxy acid as the carboxylic acid. Specifically, the carboxylic acid may be acetic acid (C2H4O2, glacial acetic acid). The carboxylic acid may be malonic acid (C3H4O4). The carboxylic acid may be maleic acid (C4H4O4). The carboxylic acid may be butyric acid (C4H8O2). The carboxylic acid may be propanoic acid (C3H6O2). The hot-dip galvanizing flux liquid 1 may contain a carboxylic acid other than the above-mentioned carboxylic acids.

[0039] When the flux liquid 1 for hot dip plating contains a carboxylic acid, the flux liquid 1 for hot dip plating has a high cleaning effect. As a result, the flux liquid 1 for hot dip plating exhibits high wettability. This makes it possible to provide a flux liquid 1 for hot dip plating that does not contain hydrochloric acid as a main acid and that has high wettability for the tin plating that coats the surface of the wire rod 3.

[0040] The hot-dip galvanizing flux liquid 1 may contain multiple types of carboxylic acids. Specifically, the hot-dip galvanizing flux liquid 1 may contain at least two types of acids (carboxylic acids) selected from malic acid, citric acid, tartaric acid (C4H6O6), acetic acid, malonic acid, maleic acid, butyric acid, and propanoic acid.

[0041] When the flux liquid 1 for hot dip plating contains multiple types of carboxylic acids, it exhibits even higher wettability. Therefore, it is possible to provide a flux liquid 1 for hot dip plating that does not contain hydrochloric acid as the main acid and that provides high wettability to the tin plating that coats the surface of the wire rod 3.

[0042] The hot-dip galvanizing flux liquid 1 may contain a plurality of different hydroxy acids. Specifically, the hot-dip galvanizing flux liquid 1 may contain both malic acid and citric acid. The hot-dip galvanizing flux liquid 1 may contain both malic acid and tartaric acid. The hot-dip galvanizing flux liquid 1 may contain both citric acid and tartaric acid.

[0043] The concentration of the carboxylic acid in the hot dip plating flux liquid 1 is preferably 0.10 (mol / liter) or more, and more preferably 0.20 (mol / liter) or more.

[0044] The surfactant is not particularly limited and any surfactant can be used, but it is preferable to use at least one of a nonionic surfactant and a cationic surfactant. Among them, nonionic surfactants are superior to cationic surfactants because they are less susceptible to electrolytes and cause less foaming. Therefore, it is preferable to use a nonionic surfactant as the surfactant.

[0045] Examples of nonionic surfactants include acetylene glycol surfactants, polyoxyalkylene alkyl ether surfactants, fatty acid alkanolamides, polyhydric alcohol surfactants, silicone nonionic surfactants, fluorine-based nonionic surfactants, etc. Among these, one or more surfactants selected from the group consisting of acetylene glycol surfactants and polyoxyalkylene alkyl ether surfactants are preferred.

[0046] Examples of commercially available nonionic surfactants include the "Surfynol" series manufactured by Nissin Chemical Industry Co., Ltd. and Air Products & Chemicals, the "Acetylenol" series manufactured by Kawaken Fine Chemicals Co., Ltd., and the "Emulgen" series manufactured by Kao Corporation. The "Surfynol" series is an example of an acetylene glycol-based surfactant, and contains acetylene glycol.

[0047] The concentration of zinc chloride contained in the hot dip plating flux liquid 1 is preferably 0.1 (mol / liter) or more, and more preferably 0.2 (mol / liter) or more.

[0048] The concentration of ammonium chloride in the hot dip plating flux liquid 1 is preferably 0.3 (mol / liter) or more, and more preferably 0.6 (mol / liter) or more.

[0049] The molar ratio of zinc chloride to ammonium chloride in the hot dip plating flux liquid 1 is not particularly limited, but is preferably 1:1 to 1:4, and more preferably 1:2 to 1:3.

[0050] The solvent contained in the hot-dip galvanizing flux liquid 1 is not particularly limited, but may usually be water (H2O). In other words, the hot-dip galvanizing flux liquid 1 may be an aqueous solution containing a carboxylic acid, a surfactant (nonionic surfactant), and at least one of zinc chloride and ammonium chloride.

[0051] The hot-dip galvanizing flux liquid 1 preferably contains both zinc chloride and ammonium chloride. In the hot-dip galvanizing flux liquid 1, one of zinc chloride and ammonium chloride may be omitted. In particular, when the carboxylic acid contained in the hot-dip galvanizing flux liquid 1 is malic acid, one of zinc chloride and ammonium chloride may be omitted. Furthermore, when the carboxylic acid contained in the hot-dip galvanizing flux liquid 1 is citric acid, zinc chloride may be omitted.

[0052] Specifically, the hot-dip galvanizing flux liquid 1 may contain malic acid, a surfactant (nonionic surfactant), and zinc chloride. In this case, the hot-dip galvanizing flux liquid 1 does not necessarily contain ammonium chloride.

[0053] The hot-dip galvanizing flux 1 may contain malic acid, a surfactant (nonionic surfactant), and ammonium chloride. In this case, the hot-dip galvanizing flux 1 does not necessarily contain zinc chloride.

[0054] Zinc chloride is generally produced by adding hydrochloric acid to zinc or zinc oxide. Zinc chloride is distributed in the form of an aqueous zinc chloride solution. The aqueous zinc chloride solution may contain a small amount of hydrochloric acid.

[0055] That is, the hot-dip plating flux liquid 1 may further contain hydrochloric acid. In this case, it is desirable that the concentration of hydrochloric acid in the hot-dip plating flux liquid 1 is sufficiently low. For example, it is preferable that the concentration of hydrochloric acid in the hot-dip plating flux liquid 1 is 0.1 (mol / liter) or less. It is even more preferable that the concentration of hydrochloric acid in the hot-dip plating flux liquid 1 is 0.02 (mol / liter) or less. Of course, the hot-dip plating flux liquid 1 does not have to contain hydrochloric acid.

[0056] The pH (hydrogen ion exponent) of the hot-dip galvanizing flux 1 is preferably less than 3.0, and more preferably 2.3 or less. If the pH of the hot-dip galvanizing flux 1 is 2.3 or more, the cleaning effect may be reduced, and oxides and the like may not be sufficiently removed from the surface of the wire 3. As a result, the wettability may be reduced.

[0057] The lower the pH value of the hot-dip plating flux liquid 1, the higher the cleaning effect, so there is no particular lower limit for the pH. However, if the pH is too low, the flux liquid becomes difficult to handle, so the pH may be 0.8 or more, and is more preferably 1.2 or more.

[0058] The method for adjusting the pH is not particularly limited, but the pH can be adjusted by changing the type of carboxylic acid or the content ratio of carboxylic acid and hydrochloric acid.

[0059] As described above, according to this embodiment, since the flux liquid 1 for hot dip plating does not contain hydrochloric acid as a main acid, it is possible to suppress or prevent hydrogen chloride (HCl) from being generated in the surroundings in the hot dip plating step S2, and therefore it is possible to reduce or eliminate the influence of hydrogen chloride remaining in the surrounding atmosphere as a vapor.

[0060] Furthermore, since the surface of the wire 3 is fluxed using the hot-dip plating flux liquid 1, the tin plating that coats the surface of the wire 3 has high wettability. This allows the surface of the wire 3 to be well coated with tin plating.

[0061] Therefore, the surface of the wire 3 can be well coated with tin plating while suppressing or preventing hydrogen chloride from evaporating and remaining in the surrounding atmosphere.

[0062] Although tin has been used as an example of the metal (molten metal) used for metal plating in the hot dip plating method, zinc, zinc alloys, aluminum, aluminum alloys, tin alloys, etc. may also be used.

[0063] The object to be plated is not limited to the wire material 3. The object to be plated may be a plate material or the like.

[0064] Although one embodiment of the present invention has been described above, it is merely an example of one embodiment of the present invention, and various modifications can be made within the scope of the claims. [Example]

[0065] The hot dip plating method of the present invention will be described based on examples, but the present invention is not limited to the following examples.

[0066] A wettability test was carried out for the present invention and the comparative examples. Specifically, a wire to be plated was fluxed using a hot-dip plating flux solution, and then the wire was tin-plated (tin-coated), and the wettability of the tin in this case was evaluated.

[0067] In the wettability test, a copper wire with a diameter of 0.6 mm and a circular cross section was used as the wire material to be plated. The copper wire was subjected to flux treatment using a hot-dip plating flux solution. The hot-dip plating flux solution used was an aqueous solution containing a carboxylic acid, a nonionic surfactant, a zinc chloride aqueous solution, ammonium chloride, and water (solvent).

[0068] Then, a wettability test was carried out by varying the type of carboxylic acid contained in the flux liquid used in the flux treatment.

[0069] The carboxylic acids contained in the hot-dip galvanizing flux solution were one or two of the following: malic acid (0.28 mol / L), citric acid (0.20 mol / L), tartaric acid (0.25 mol / L), acetic acid (glacial acetic acid, 0.63 mol / L), malonic acid (0.37 mol / L), maleic acid (0.33 mol / L), butyric acid (0.43 mol / L), and propanoic acid (0.51 mol / L). The values ​​in parentheses indicate the concentrations of the carboxylic acids in the hot-dip galvanizing flux solution.

[0070] The nonionic surfactant used was a mixed Surfynol, created based on the Surfynol series manufactured by Nissin Chemical Industry Co., Ltd. and Air Products & Chemicals. This mixed Surfynol was obtained by mixing methyloxirane polymer with oxirane, ether with 2,4,7,9-tetramethyl-5-decyne-4,7-diol (2:1) (CAS number 182211-02-5) and 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate (CAS number 9014-85-1) in a 1:1 ratio. Specifically, the amount of nonionic surfactant was 0.5 milliliters per 100 milliliters of hot-dip plating flux solution.

[0071] In the present invention examples of Test No. T13, Test No. T23 and Test No. T26, the amount of nonionic surfactant contained in the hot dip plating flux liquid (100 milliliters (mL)) was 0.06 milliliters (mL).

[0072] In the present invention examples of Test No. T14, Test No. T24 and Test No. T27, the amount of nonionic surfactant contained in the hot dip plating flux liquid (100 milliliters) was 2.0 milliliters.

[0073] The zinc chloride aqueous solution contained in the hot dip plating flux liquid contains zinc chloride (70.02 wt%), hydrochloric acid (1.1 wt%), and water (28.7 wt%). The values ​​in parentheses indicate the content (wt%) of each component in the zinc chloride aqueous solution.

[0074] The mass of zinc chloride solution contained in the hot-dip galvanizing flux solution (100 milliliters) is 4.4 g. The proportion of zinc chloride in the zinc chloride solution is 70.02 wt%, so the concentration of zinc chloride in the hot-dip galvanizing flux solution is 0.226 (mol / liter). The proportion of hydrochloric acid in the zinc chloride solution is 1.1 wt%, so the concentration of hydrochloric acid in the hot-dip galvanizing flux solution is 0.0133 (mol / liter).

[0075] In the test with test number T30, the mass of zinc chloride aqueous solution contained in the hot-dip galvanizing flux solution (100 milliliters) was 1.0 g. Since the proportion of zinc chloride in the zinc chloride aqueous solution was 70.02 wt%, the concentration of zinc chloride in the hot-dip galvanizing flux solution was 0.051 (mol / liter). Since the proportion of hydrochloric acid in the zinc chloride aqueous solution was 1.1 wt%, the concentration of hydrochloric acid in the hot-dip galvanizing flux solution was 0.0030 (mol / liter).

[0076] In the tests T31 and T32, the mass of zinc chloride aqueous solution contained in the hot-dip galvanizing flux solution (100 milliliters) was 2.2 g. Since the proportion of zinc chloride in the zinc chloride aqueous solution was 70.02 wt%, the concentration of zinc chloride in the hot-dip galvanizing flux solution was 0.113 (mol / liter). Since the proportion of hydrochloric acid in the zinc chloride aqueous solution was 1.1 wt%, the concentration of hydrochloric acid in the hot-dip galvanizing flux solution was 0.0066 (mol / liter).

[0077] The ammonium chloride contained in the hot-dip galvanizing flux liquid is solid (powdered). The mass of ammonium chloride contained in the hot-dip galvanizing flux liquid (100 milliliters) is 3.0 g. In this case, the concentration of ammonium chloride in the hot-dip galvanizing flux liquid is 0.56 (mol / liter (mL)).

[0078] For test number T30 only, the mass of ammonium chloride contained in the hot-dip galvanizing flux liquid (100 milliliters) was 1.0 g. At this time, the concentration of ammonium chloride in the hot-dip galvanizing flux liquid was 0.19 (mol / liter (mL)).

[0079] The types of carboxylic acids contained in the flux liquid for hot dip plating and the pH of the flux liquid for hot dip plating are shown in Figures 3 to 5. The temperature of the flux liquid in the flux treatment was 25°C (room temperature).

[0080] In each wettability test, the wire to be plated was passed through a flux solution stored in a flux tank and then immersed in molten tin stored in a plating tank. The molten tin temperature was 250°C, the immersion speed was 4 mm / sec, the immersion depth was 2 mm, and the immersion time was 5 seconds. After the immersion time had elapsed, the wire was pulled up at a pulling speed of 4 mm / sec and dried to obtain a tin-plated wire. The wettability of the tin to the wire during the pulling up process was then evaluated.

[0081] Fig. 6 is a graph showing the test results of the wettability test for an example of the present invention (Test No. T12). Fig. 7 is a graph showing the test results of the wettability test for a comparative example (Test No. T0). As shown in Figs. 6 and 7, the meniscograph method was used to evaluate the wettability of tin. The higher the wettability of tin, the shorter the zero cross time ZT and the greater the maximum wetting force FF.

[0082] 3 and 7, among the comparative examples, test number T0 is an example in which Azonyl (specifically, Azonyl No. 1 (trade name, manufactured by Kaname Chemical Co., Ltd.)) was used as the hot-dip galvanizing flux liquid. In test number T0, the zero cross time ZT was 0.65 seconds and the maximum wetting force FF was 0.53 mN.

[0083] Specifically, Azonyl No. 1 contains hydrochloric acid (HCl), zinc chloride (ZnCl2), ammonium chloride (NH4Cl), and water (solvent, HO). The hydrochloric acid content (mass) is 0.2 wt% or more and 9.7 wt% or less. The zinc chloride content (mass) is 1.4 wt% or more and 3.2 wt% or less. The ammonium chloride content (mass) is 0.3 wt% or more and 0.4 wt% or less. The remainder is water, and its content (mass) is 86.7 wt% or more and 98.1 wt% or less. More specifically, the component ratios of chlorine (Cl), zinc (Zn), and ammonia (NH3) contained in Azonyl No. 1 relative to Azonyl No. 1 (100%) are approximately 3.85 wt%, approximately 0.67 wt%, and approximately 0.13 wt%, respectively. Azonyl contains hydrochloric acid as the main acid, as well as ammonium chloride and zinc chloride. Therefore, in Figures 3 to 5, the "zinc chloride solution" and "ammonium chloride" columns are marked with "present."

[0084] The zero cross time ZT of each wettability test was evaluated using the following criteria: if it was less than 0.53 seconds, "◎", if it was 0.53 seconds or more and 0.65 seconds or less, "○", if it was more than 0.65 and 0.73 seconds or less, "△", and if it was more than 0.73 seconds, "×". As mentioned above, the zero cross time ZT of test number T0 was 0.65 seconds, so if the zero cross time ZT was evaluated as "◎" or "○", this means that the zero cross time ZT was the same as or shorter than Azonyl (test number T0).

[0085] In FIGS. 3 to 5, when the zero cross time ZT cannot be measured, it is described as "immeasurable."

[0086] The maximum wetting force FF of each wettability test was evaluated using the following criteria: if it was over 0.63 mN, it was marked "◎", if it was 0.53 mN or more and 0.63 mN or less, it was marked "○", if it was 0.48 mN or more and less than 0.53 mN, it was marked "△", and if it was less than 0.48 mN, it was marked "×". As mentioned above, the maximum wetting force FF of Azonyl (test number T0) is 0.53 mN, so if the maximum wetting force FF is rated "◎" or "○", it means that the maximum wetting force FF is equal to or greater than that of Azonyl. If the maximum wetting force FF is rated "×", it means that the maximum wetting force FF is inferior to that of Azonyl.

[0087] In Figs. 3 to 5, when the maximum wetting force FF cannot be measured, it is described as "impossible to measure."

[0088] Furthermore, in each wettability test, the zero cross time ZT and maximum wetting force FF were taken into consideration, and each test was evaluated for tin wettability using the criteria of "◎", "○" and "×". A rating of "◎" indicates better wettability than Azonyl. A rating of "○" indicates wettability that is the same as Azonyl or slightly better than Azonyl.

[0089] The test results are shown in FIGS.

[0090] It was found that the examples of the present invention had excellent wettability, whereas the comparative examples that did not satisfy the conditions of the present invention had poor wettability.

[0091] Furthermore, in test number T35, which is an example of the present invention, no tin plating was formed on the wire material. This shows that when tartaric acid is used as the carboxylic acid, the wettability of tin is significantly poor.

[0092] In addition, in test number T30, which is an example of the present invention, no tin plating was formed on the wire rod. This is thought to be due to the low concentration of carboxylic acid and the slightly high pH value of the hot-dip plating flux solution.

[0093] Test No. T7, an example of the present invention, also had poor wettability with tin. Test No. T7 is an example in which citric acid was used as the carboxylic acid. Furthermore, the example of the present invention, Test No. T7, did not contain ammonium chloride.

[0094] In contrast, the inventive example of test number T11, which also used citric acid as the carboxylic acid, had good wettability of tin. The inventive example of test number T11 did not contain zinc chloride (aqueous zinc chloride solution).

[0095] On the other hand, the inventive examples of test numbers T18 and T20 were examples in which citric acid was used as the carboxylic acid and did not contain either ammonium chloride or zinc chloride (aqueous zinc chloride solution).However, in both inventive examples, the wettability of tin was good.

[0096] Furthermore, it was found that the inventive examples of test numbers T22 to T24, which used malic acid as the carboxylic acid, had superior wettability to tin compared to other carboxylic acids such as citric acid.

[0097] Furthermore, in the present invention examples of test numbers T25, T26, T27, T28, T29, T33 and T34, which used multiple (two) types of carboxylic acids, it was found that the wettability of tin was superior compared to when one type of carboxylic acid was used.

[0098] Furthermore, in several wettability tests, the hydrogen chloride concentration in the atmosphere surrounding the hot-dip plating equipment 2 was measured. Specifically, in an example of the present invention (Test No. T12) and a comparative example (Test No. T0), a gas sampler (Gas Sampler Set GV-100S manufactured by Gastec Corporation) was used to sample the atmosphere at a measurement position MP (FIG. 1) directly above the plating tank 6, and the hydrogen chloride concentration in the atmosphere was measured. The measurement position MP was located on the upper surface (molten metal surface) of the hot-dip plating flux liquid stored in the plating tank 6, directly above the immersion position IP of the wire 3 (more specifically, 5 cm above the immersion position IP). The measurement results are shown in FIG. 8.

[0099] As shown in Fig. 8, the hydrogen chloride concentration at the measurement position MP in the example of the present invention (test number T12) was 2 ppm, while the hydrogen chloride concentration at the measurement position MP in the comparative example (test number T0) was 30.4 ppm. Fig. 8 shows that when hot-dip galvanizing flux solution 1 containing a carboxylic acid (citric acid) as the main acid was used, the hydrogen chloride concentration at the measurement position MP was significantly reduced compared to when Azonyl (Azonyl No. 1) containing hydrochloric acid as the main acid was used.

[0100] This shows that when the hot-dip plating flux liquid 1 is used as the hot-dip plating flux liquid, the amount of hydrogen chloride (HCl) remaining in the atmosphere surrounding the hot-dip plating equipment 2 can be significantly reduced compared to when Azonyl (Azonyl No. 1) is used.

[0101] Therefore, according to the present embodiment, by using the flux liquid 1 for hot dip plating as the flux liquid for hot dip plating, it is possible to satisfactorily coat the surface of the object to be plated with a metal plating while suppressing or preventing hydrogen chloride from evaporating and remaining in the surrounding atmosphere (while significantly suppressing hydrogen chloride from remaining in the surrounding atmosphere). [Explanation of symbols]

[0102] 1: Flux liquid for hot dip plating 3: Wire material (object to be plated) 6: Plating tank

Claims

1. A plurality of different carboxylic acids, A surfactant, Contains at least one of zinc chloride and ammonium chloride, The carboxylic acid includes at least one of acetic acid, malonic acid, maleic acid, butyric acid, and propanoic acid.

2. A compound comprising: a plurality of different carboxylic acids; A surfactant, Contains at least one of zinc chloride and ammonium chloride, The flux solution for hot dip plating, wherein the surfactant comprises an acetylene-based nonionic surfactant.

3. The flux solution for hot dip plating according to claim 1 or 2, wherein the carboxylic acid includes a hydroxy acid.

4. 4. The flux solution for hot dip plating according to claim 3, wherein the hydroxy acid includes at least one of malic acid and citric acid.

5. a fluxing step of fluxing the surface of the object to be plated using a flux solution for hot dip plating; a hot-dip plating step of immersing the object to be plated after the flux step in a plating tank and then lifting it out of the plating tank to coat the surface of the object to be plated with a metal plating, The hot-dip plating flux solution used in the fluxing step contains a plurality of different carboxylic acids, a surfactant, and at least one of zinc chloride and ammonium chloride, The hot dip coating method, wherein the carboxylic acid comprises at least one of acetic acid, malonic acid, maleic acid, butyric acid, and propanoic acid.

6. A fluxing process for fluxing the surface of an object to be plated using a flux solution for hot dip plating; a hot-dip plating step of immersing the object to be plated after the flux step in a plating tank and then lifting it out of the plating tank to coat the surface of the object to be plated with a metal plating, The hot-dip plating flux solution used in the fluxing step contains a plurality of different carboxylic acids, a surfactant, and at least one of zinc chloride and ammonium chloride, The hot dip plating method, wherein the surfactant comprises an acetylenic nonionic surfactant.

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