JP5630692B2 - Zinc-iron alloy plating solution - Google Patents

Description

  The present invention relates to a zinc-iron alloy plating solution and a plating method which are particularly suitable for coloring a black color by subjecting a zinc-iron alloy plating film to trivalent chromium conversion coating treatment and non-chromium conversion coating treatment, particularly black conversion coating treatment. The present invention relates to a trivalent chromium black chemical conversion film treatment method, a non-chromium black chemical conversion film treatment method, a trivalent chromium white chemical conversion film treatment, and a non-chromium white chemical conversion film treatment.

  Zinc alloy plating such as zinc-iron alloy plating is widely performed for the purpose of improving the corrosion resistance of zinc plating. Among them, zinc-iron alloy plating is widely used for parts such as automobile parts that require particularly high corrosion resistance. In the conventional zinc-iron alloy plating, as disclosed in Japanese Patent Laid-Open No. 60-181293, electrolytic plating is performed in an alkaline electrogalvanizing bath containing iron solubilized with a chelating agent. This is done by a method of depositing iron.

  There is a method of reacting a sulfur compound or an oxygen acid of phosphorus with a metal as a method currently used as a method of performing a trivalent chromium black chemical conversion film treatment on a galvanized film. For example, Japanese Patent Application Laid-Open No. 2003-213446 discloses a method of forming a black chemical conversion film by treating with an aqueous solution containing an oxidizing substance such as trivalent chromium, sulfite ions, nitric acid, and phosphorus oxygen acid. Describes a method of forming a black chemical conversion film by treating with a treatment solution containing trivalent chromium, inorganic acid ions, and a sulfur compound. The former is a method of applying an overcoat after the chemical conversion film is formed, and the latter is a chemical conversion film. A method of treating with a second treatment liquid containing one or more selected from the group consisting of trivalent chromium, a surfactant and a silicon compound after formation is disclosed. It is known that the same trivalent chromium black chemical conversion film treatment as that of the zinc plating film can be usually applied to the zinc-iron alloy plating film.

  As for the method of performing the non-chromium black chemical conversion film treatment, for example, JP-A-2008-214744 is cited in zinc-based plating. This is a method of forming a non-chromium black chemical conversion film using aluminum, antimony, phosphoric acid, and thio compounds. However, there are only examples of zinc plating in the examples, and it is experimentally confirmed whether it can be applied to zinc alloy plating. In addition, since there is a difference in the procedure from the existing trivalent chromium black chemical conversion film treatment, there are many sites where existing facilities cannot be used, and the cost of capital investment and the like increases.

  In the past, examples in which a non-chromium black chemical conversion coating was applied to exhibit corrosion resistance equivalent to or higher than that of the trivalent chromium black chemical conversion coating on the current zinc plating have not been confirmed in any zinc-based alloy plating.

  In addition, there are many prior arts such as Japanese Patent Application Laid-Open No. 2003-166075, Japanese Patent Application Laid-Open No. 2005-126797, Japanese Patent Application Laid-Open No. 2005-240068, and Japanese Patent Application Laid-Open No. 2007-32234. Exists.

  Regarding the non-chromium white chemical conversion film treatment, unlike black, there are prior arts such as Japanese Patent Application Laid-Open No. 2007-23353, Japanese Patent Application Laid-Open No. 2008-133502, and Japanese Patent No. 3523383.

JP-A-60-181293 JP 2003-213446 A JP 2005-206872 A JP 2008-214744 A Japanese Patent Laid-Open No. 2003-166075 Japanese Patent Laid-Open No. 2005-126797 Japanese Patent Laid-Open No. 2005-240068 JP 2007-32234 A JP 2007-23353 A JP 2008-133502 A Japanese Patent No. 3523383

  When a trivalent chromium conversion coating is applied to a coating formed by zinc-iron alloy plating, there is a large difference in the finish after the conversion coating depending on the bath composition of the zinc-iron alloy plating solution, the type and concentration of brightener and chelating agent. A large variation occurs. The plating performed with the concentration range and additives shown in the above-mentioned patent document was able to stably form a uniform conversion film in the main treatment of hexavalent chromium conversion film at that time. , Trivalent chromium conversion coating treatment, especially black conversion coating treatment, deterioration of appearance and corrosion resistance or variation depending on the product can be seen even within the application range, more uniform and compatible with trivalent chromium conversion coating treatment A good zinc-iron alloy plating has been demanded.

Further, in the conventional zinc-iron alloy plating solution, the allowable current density range is small on the high current side, and the work efficiency is poor. When plating is carried out at a cathode current density exceeding 3 A / dm ² in static plating, the appearance of the burnt surface becomes terrible and a good zinc-iron alloy plating film cannot be formed. In galvanization, it is possible to form a good plating film even at a higher current density, which leads to low working efficiency in zinc-iron alloy plating and is a major factor that impairs productivity.

  In addition, it is known that trivalent chromium in the trivalent chromium conversion coating may be transformed into hexavalent chromium, which is highly harmful to the environment, and may be eluted. May be regulated. Therefore, it is an important issue to establish a technology for non-chromic conversion coating treatment, particularly non-chromium black conversion coating treatment, in zinc-iron plating.

  As a result of intensive research by the present inventors, gallic acid or a salt thereof as an essential component is added to zinc-iron alloy plating, a quaternary ammonium polymer is added as a brightening agent, and the bath composition is reexamined accordingly. While improving the drainage of the liquid, the range of applicable current density was expanded, and the performance of the subsequent trivalent chromium black chemical conversion film was successfully improved.

  Specifically, 0.1-5 g of one or more selected from divalent or higher polyvalent carboxylic acids, oxycarboxylic acids, aminocarboxylic acids or salts thereof as chelating agents in the zinc-iron alloy plating solution. By adding 0.2 to 5 g / L of quaternary ammonium polymer, it is possible to obtain the same or better appearance even if the concentration of each component is suppressed to a lower concentration than the conventional zinc-iron alloy plating solution, The eutectoid rate of iron in the plating film and the plating film thickness were the same as the conventional zinc-iron alloy plating, and it succeeded in forming a plating film with higher uniformity. Furthermore, it has the effect of greatly improving the drainage of the plating solution and succeeded in greatly expanding the applicable current range.

  With regard to the trivalent chromium black chemical conversion coating solution, the existing chemicals used in the trivalent chromium black chemical conversion treatment of galvanization can be used. is there.

  In addition, in the non-chromium black conversion coating treatment, the appearance and corrosion resistance are equivalent to or better than the trivalent chromium black conversion coating treatment on galvanization by performing conversion treatment with an aqueous solution in which phosphorus oxoacid ions and nitrogen oxoacid ions are dissolved. The present inventors have found a method of forming a film that exhibits The oxo acid ions of nitrogen have the effect of etching and activating the zinc-iron alloy plating film, and the oxo acid ions of phosphorus form a phosphate film having corrosion resistance and the iron in the zinc-iron alloy plating film. It has the effect of reacting and blackening.

  Yttrium ions can be further added to the above-mentioned non-chromium black chemical conversion coating solution. Although the mechanism is unknown, the film formation reaction and the blackening reaction can be moderately suppressed, and a more uniform black film can be formed. As a result, it has the effect of improving the running property of the treatment liquid.

  Tin compounds and vanadium compounds have the effect of contributing to improvement of the corrosion resistance of the coating by entering the phosphate coating. These components are considered to have the effect of precipitating together with the above-mentioned basic components for film formation or making the film denser, and contribute to appearance and corrosion resistance.

  Based on the above knowledge, one aspect of the present invention is that 8 to 16 g / L zinc ions, 0.08 to 0.30 g / L iron ions, 40 to 65 g / L hydroxide ions, In an aqueous solution containing 30 g / L of a chelating agent, the quaternary ammonium polymer is further selected from 0.2 to 5 g / L, divalent or higher polyvalent carboxylic acid, oxycarboxylic acid, aminocarboxylic acid or a salt thereof. It is a zinc-iron alloy plating solution containing 0.1 to 5 g / L of one or more types.

  Furthermore, in one embodiment of the present invention, the zinc-containing chelating agent is one or more selected from amino alcohols, tertiary or lower polyamines, polyhydric alcohols, and thioureas. It is an iron alloy plating solution.

  Furthermore, in one embodiment, the present invention is a method for performing zinc-iron alloy plating using the above plating solution.

  Furthermore, in one embodiment, the present invention is a film forming method characterized by performing a non-chrome black chemical conversion film treatment after plating with the plating solution.

  Further, in one embodiment of the present invention, the non-chromium black chemical conversion treatment is characterized in that the treatment liquid for performing the non-chromium black chemical conversion film treatment contains both one or more of oxo acid ions of phosphorus and oxo acid ions of nitrogen. This is a film forming method.

  Furthermore, the present invention is the non-chromium black chemical conversion film forming method according to one embodiment, wherein the treatment liquid further contains yttrium ions.

  Furthermore, in one embodiment, the present invention is the above-described method for forming a non-chrome black conversion coating, wherein the treatment liquid further contains one or more selected from tin ions and vanadium ions.

  Furthermore, in one embodiment of the present invention, the treatment solution contains 1 to 100 g / L of phosphorus oxoacid ions and 0.1 to 30 g / L of one or more of oxoacid ions of nitrogen. The method for forming a non-chromium black chemical conversion film as described above.

  Furthermore, in one embodiment, the present invention provides the method as described above, wherein the treatment liquid contains 2 to 100 mg / L of yttrium ions in the form of an inorganic acid and an yttrium salt.

  Furthermore, in one embodiment, the present invention is the above-described method, wherein the treatment liquid contains 10 to 550 mg / L of tin ions and / or 0.01 to 10 g / L of vanadium ions.

  Furthermore, in one embodiment, the present invention is a film forming method characterized by performing a non-chromium white chemical conversion film treatment after plating with the plating solution.

  Furthermore, the present invention is, in one embodiment, a film forming method characterized in that after the non-chromium film forming process, a dipping process is performed once or a plurality of times with a second processing liquid.

  Furthermore, in one embodiment, the present invention is a metal base material on which a non-chromic chemical conversion film is formed using the method described above.

  Furthermore, in one embodiment, the present invention is a film forming method characterized by performing a trivalent chromium black chemical conversion film treatment after plating with the plating solution.

  Furthermore, in one embodiment, the present invention is one or more times in a second treatment liquid containing one or more selected from the group consisting of trivalent chromium, a surfactant and a silicon compound after forming a film by the above method. The film forming method is characterized in that the treatment is performed once.

  Furthermore, this invention is the metal base material which formed the trivalent chromium black chemical conversion film in one Embodiment using the said method in one Embodiment.

  Furthermore, this invention is a film formation method characterized by performing a trivalent chromium white chemical conversion film treatment after plating with said plating solution in one Embodiment.

  Furthermore, this invention is the metal base material which formed the trivalent chromium white chemical conversion film in one embodiment using the said method.

Photograph of iron plate that has been plated

  Hereinafter, the zinc-iron alloy plating solution of the present invention will be described in detail. In the present invention, in order to obtain a film having an excellent appearance with a trivalent chromium black chemical conversion film and a non-chromium black chemical conversion film after plating, a quaternary ammonium polymer is more preferably 0.2 to 5 g / L in the plating solution. Is added 0.5 to 2 g / L, further zinc ions 8 to 16 g / L, iron ions 0.08 to 0.30 g / L, hydroxide ions 40 to 65 g / L, chelating agents 10 to 30 g / L, A zinc-iron alloy known so far in which 0.1 or 5 g / L of one or more selected from divalent or higher polyvalent carboxylic acids, oxycarboxylic acids, aminocarboxylic acids or salts thereof is used. Contains each component at a lower concentration than the plating solution. Alkali hydroxide refers to a salt in which hydroxide ions and alkali metal ions are ion-bonded.

  The quaternary ammonium polymer is a polymer containing a quaternary ammonium salt in the repeating unit, and specific examples thereof include structural formulas (1) to (8), but are not limited thereto. A chelating agent is a molecule having a functional group capable of coordinating with an iron ion, for example, a divalent or higher polyvalent carboxylic acid, an oxycarboxylic acid, an aminocarboxylic acid or a salt thereof, or an amino alcohol, a tertiary or lower class. Examples include, but are not limited to, polyamines, polyhydric alcohols, and thioureas. An oxycarboxylic acid is a carboxylic acid containing both a hydroxyl group and a carboxyl group in one molecule. An aminocarboxylic acid is a carboxylic acid containing both an amino group and / or an imino group and a carboxyl group in one molecule. Amino alcohols are alcohols containing both amino groups and / or imino groups and hydroxyl groups in one molecule. Tertiary or lower polyamines are polymers containing tertiary or lower amines in the repeating unit. Thioureas are molecules in which hydrogen in thiourea or thiourea molecules is substituted with other substituents.

(In the formula, R 1 and R 2 are each independently hydrogen, methyl, ethyl, propyl, isopropyl, butyl, —CH ₂ CH ₂ (OCH ₂ CH ₂ ) _X OH (X is 0 to 5) or —CH ₂ CH _2. A polymer represented by (OCCH ₂ CH ₂ ) _X OH (X represents 0 to 5 and n represents 1 or more), structural formula (2)

Wherein R 1, R 2, R 3 and R 4 are each independently hydrogen, methyl, ethyl, isopropyl, 2-hydroxylethyl-CH ₂ CH ₂ (OCH ₂ CH ₂ ) x OH (X is 0 to 6) or 2- It represents hydroxyl ethyl _{-CH 2 CH 2 (OCCH 2 CH} 2) xOH (X is Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O- (CH ₂ ) ₂ —O— (CH ₂ ) ₂ or CH ₂ —CHOH—CH ₂ —O—CH ₂ —CHOH—CH ₂ , n is 1 or more, and Y is S or O). Polymer, structural formula (3)

Wherein R 1, R 2, R 3 and R 4 are each independently hydrogen, methyl, ethyl, isopropyl, 2-hydroxylethyl-CH ₂ CH ₂ (OCH ₂ CH ₂ ) x OH (X is 0 to 6) or 2- It represents hydroxyl ethyl _{-CH 2 CH 2 (OCCH 2 CH} 2) xOH (X is Less than six), R5 is _{(CH 2) 2 -O- (CH} 2) 2, (CH 2) 2 -O- (CH ₂ ) ₂ —O— (CH ₂ ) ₂ or CH ₂ —CHOH—CH ₂ —O—CH ₂ —CHOH—CH ₂ , n represents 1 or more, and Y represents S or O. Polymer, structural formula (4)

Wherein R1 and R2 are each independently hydrogen, methyl, ethyl, isopropyl, butyl, —CH ₂ CH ₂ (OCH ₂ CH ₂ ) _X OH (X is 0 to 5) or —CH ₂ CH ₂ (OCCH ₂ CH ₂ ) _X OH (X represents 0 to 5 and Y represents O or S) as a monomer, structural formula (5)

(Wherein, independently hydrogen each R1 or R2, represents methyl, ethyl, butyl or isobutyl, R3 represents CH _2, C ₂ H ₄ or C ₃ H _6, n is 1 or more) in the table Polymer, structural formula (6)

Wherein R1 and R2 each independently represent hydrogen or alkyl having 10 or less carbon atoms, and n represents 1 or more, structural formula (7)

(Wherein R1, R2, R3 and R4 each independently represents hydrogen or alkyl having 5 or less carbon atoms, X represents an inorganic anion, n represents 1 or more, and Y represents S or O) And a structural formula (8)

(In the formula, R1, R2, R3 and R4 each independently represent hydrogen or alkyl having 5 or less carbon atoms, X represents an inorganic anion, m and n represent 1 or more, and Y represents S or O. Represents)
In addition, although it does not limit about the value of n or m + n in the said Structural formula (1)-(8), Preferably it is 2-10 on an average, More preferably, it is 4-8.

  If the zinc ion concentration is too high, the amount of necessary brightener increases, which is uneconomical and the uniformity of the coating is reduced, and in the case of a complicated shaped member, the unevenness to the low current part is weakened. . If it is too low, the plating rate will decrease. Therefore, the zinc ion concentration of the present invention is 8 to 16 g / L, more preferably 10 to 14 g / L. If iron ions are too high or too low, the iron eutectoid rate in the film will not be an appropriate value, and the appearance of the plating film and the appearance after the chemical conversion film will not only deteriorate, but the necessary corrosion resistance will be obtained. Absent. Therefore, the iron ion concentration of the present invention is 0.08 to 0.30 g / L, and more preferably 0.10 to 0.25 g / L. It is known that if the hydroxide ion is too high, it will destroy the brightener molecules and increase the amount of brightener required, which is uneconomical. If it is too low, the uniformity of the film and the thickness of plating will deteriorate. Therefore, the hydroxide ion concentration of the present invention is 40 to 65 g / L, more preferably 45 to 60 g / L. If the chelating agent concentration and the quaternary ammonium polymer concentration are too high, the current efficiency decreases. In particular, for a chelating agent, the time and effort for wastewater treatment also increases. If it is too low, the uniformity of the film deteriorates, and not only the appearance of the plating film but also the appearance after the chemical conversion film treatment is deteriorated. Therefore, the concentration of the chelating agent of the present invention is 10 to 30 g / L, more preferably 15 to 25 g / L. In addition to the chelating agent, the concentration of the chelating agent selected from divalent or higher polyvalent carboxylic acids, oxycarboxylic acids, aminocarboxylic acids or salts thereof is 0.1 to 5 g / L, preferably 0. 0.5-2 g / L. Moreover, the density | concentration of the quaternary ammonium polymer of this invention is 0.2-5 g / L, More preferably, it is 0.5-2 g / L.

  In the plating solution of the present invention, a brightener used for an existing alkaline zinc-iron plating bath can be further used. For example, it is possible to contain one or more benzothiazoles, benzoxazoles, aliphatic amine derivatives and the like.

  As for the trivalent chromium black and white chemical conversion film treatment, it is possible to directly use a treatment liquid for forming a trivalent chromium black and white chemical conversion film on the conventional zinc plating and zinc-iron alloy plating. The surface treatment procedure and conditions are the same as those for the conventional zinc-iron alloy plating. In addition, the trivalent chromium black chemical conversion film is a chemical conversion film mainly composed of trivalent chromium, and the color tone is black, and the trivalent chromium white chemical conversion film is a chemical conversion film mainly composed of trivalent chromium. And the thing which has the color tone of the white-silver type which has an interference color is pointed out.

  In particular, the existing second treatment liquid can be used as it is for the second treatment liquid (finishing liquid) generally used after the formation of the trivalent chromium black chemical conversion film. For example, an aqueous solution containing both chromium phosphate and malonic acid can be used, but is not limited thereto.

  The non-chromium black chemical conversion film forming reaction can be achieved by using a metal surface treatment solution containing phosphorus oxoacid ions and nitrogen oxoacid ions and not containing chromium.

  Examples of oxo acids of phosphorus include, but are not limited to, phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid and salts thereof, and 1 to 100 g / L, more desirably 10 to 40 g. It is desirable to use within the range of / L. When the concentration is low, blackening is insufficient, and a sufficient film is not formed, resulting in low corrosion resistance. At high concentrations, the reaction is excessive and a uniform black appearance cannot be obtained.

  The source of nitrogen oxo acid ions is supplied as nitric acid or various metal nitrates and nitrites. The nitrogen oxoacid ion is desirably used in the range of 0.1 to 30 g / L, more preferably 2 to 10 g / L. At low concentrations, the reaction does not proceed sufficiently, and a film having good appearance and corrosion resistance is not formed. At a high concentration, the reaction becomes excessive and a good film is not formed.

  The source of yttrium ions is preferably in the form of an inorganic acid and a salt of yttrium, and particularly preferably yttrium nitrate, but is not limited. The concentration of yttrium nitrate hexahydrate is 2-100 mg / L, more preferably 5-30 mg / L. If the addition amount is too small, the effect of yttrium will not be exhibited, and even if it is added excessively, the effect will reach its peak and the economy will be impaired.

  The source of the tin compound is not particularly limited as long as it is a water-soluble compound, but nitrate, sulfate or chloride is preferable, and tin sulfate is particularly preferable. The tin concentration is preferably 10 mg / L to 550 mg / L, more preferably 100 mg / L to 300 mg / L. If the addition amount is too small, the effect of tin is not exhibited, and if it is added excessively, the formation of a normal film may be hindered.

The source of vanadium compound is not critical, for example, vanadium chloride (VCl _2, VCl _3, and VCl _4), dichloride vanadyl (VOCl _2), vanadium bromide (VBr _2, VBr _3), iodide vanadium (VI ₂ , VI ₃ ), vanadium sulfate (VSO ₄ , V ₂ (SO ₄ ) ₃ ), vanadyl sulfate (VOSO ₄ ), vanadium nitrate (V (NO ₃ ) ₂ , V (NO ₃ ) ₃ ), vanadium pentoxide ( V ₂ O ₅ ), vanadate (H ₃ VO ₄ ), potassium orthovanadate (K ₃ VO ₄ ), sodium orthovanadate (Na ₃ VO ₄ ), lithium orthovanadate (Li ₃ VO ₄ ) potassium metavanadate (KVO _3), sodium metavanadate (NaVO _3), lithium metavanadate (LiVO _3), ammonium metavanadate (NH ₄ VO _3), etc., and especially Vanadate preferred but not limiting. The concentration of vanadium is preferably 0.01 to 10 g / L, more preferably 0.1 to 2 g / L. If the addition amount is too small, the effect of vanadium will not be exhibited, and even if it is added excessively, the effect will reach its peak and the economic efficiency will be impaired.

  As immersion conditions for forming the non-chromium black conversion coating, it is preferable that the temperature is in the range of 10 to 50 ° C. and pH of 1.0 to 3.0, more preferably 20 to 40 ° C. and pH of 1.5 to 2.5. Range. At low temperatures, a sufficient film is not formed, and at high temperatures, the appearance tends to become cloudy and the workability is impaired. At low pH, excessive reaction occurs and a sufficient film is not formed. At high pH, it is difficult to form a film due to insufficient reaction. The dipping time is 20 to 120 seconds, preferably 30 to 90 seconds. If the immersion time is 20 seconds or less, there is a high possibility that a sufficient film thickness cannot be obtained. Soaking for 120 seconds or more leads to deterioration of appearance and corrosion resistance due to excessive reaction. Moreover, in order to form a film | membrane uniformly, it is preferable that there is stirring, and it is preferable to wash a to-be-processed object after chemical conversion treatment.

  After the above chemical conversion treatment, after washing with water, coating with an inorganic, organic or organic-inorganic composite will further improve the corrosion resistance. Examples of inorganic overcoats include silica-based and phosphoric acid-based overcoats, but other overcoats are also possible. The organic overcoat is not particularly limited with respect to the coating material and the resin type, and can be applied to an aqueous overcoat or non-aqueous overcoat. For example, polyethylene, polyvinyl chloride, polystyrene, polypropylene, acrylic resin, methacrylic resin, polycarbonate, polyamide, polyacetal, fluororesin, urea resin, phenol resin, unsaturated polyester resin, polyurethane, alkyd resin, epoxy resin, melamine resin, etc. Although a film | membrane is mentioned, it is not limited to these. Further, overcoating may be performed immediately after the surface treatment according to the present invention, but it is also effective if it is performed after drying and after processing such as pressing and bending, and it is also effective to perform the coating several times. The method of overcoat is not particularly limited, and various methods such as coating, immersion coating, electrostatic coating, electrodeposition coating, and powder coating are possible.

  The non-chromium white conversion film forming reaction contains at least one selected from the group consisting of vanadium group element compounds, rare earth element ions and chlorine ions, fluorine ions, nitrate ions, sulfate ions and acetate ions, and also contains chromium. No, it is performed by immersing in a metal surface treatment solution having a temperature of 10 to 50 ° C. and a pH of 1.0 to 5.0 for 20 to 120 seconds. When the coating is performed after the above chemical conversion treatment and after washing with water, the corrosion resistance is further improved.

  The above-described treatment of the present invention is used for a metal substrate. The metal substrate is a substrate having a metal surface, and specifically includes, but is not limited to, a metal plate and a bolt.

Hereinafter, the present invention will be described with reference to Examples , Reference Examples and Comparative Examples. After performing an appropriate pretreatment on the test piece, plating was performed according to the following examples and reference examples . Unless otherwise specified in the following examples and reference examples , the test piece to be a cathode is an iron plate (50 × 100 × 2 mm) for static plating, a bolt (M8 × 50 mm) is used for barrel plating, and an iron plate is also used for the anode. Using. Plating Conditions Plating bath temperature 25 ° C., plating time still plating 30 minutes and barrel plating 60 minutes, the current density is still plated 3A / dm ² (Comparative Examples 1 to 3 2A / dm ^2), barrel plating 0.8 A / an dm ^2, iron sulfate to a source of iron ions, zinc oxide to a source of zinc ions, sodium hydroxide to a source of hydroxide ion, triethanolamine chelating agents, quaternary ammonium polymer Used the one having the structure of the structural formula (1) and R1 and R2 being methyl. The non-chromium white chemical conversion film treatment was performed using an aqueous solution containing lithium nitrate 20 g / L, cerium sulfate 10 g / L, and potassium metavanadate 2 g / L at a temperature of 30 ° C., a treatment time of 60 seconds, and a pH of 2.8. The second treatment after washing with water was carried out using a 5% aqueous solution of colloidal silica and immersed at 30 ° C. for 30 seconds at pH 11. The trivalent chromium black chemical conversion treatment uses an aqueous solution containing chromium nitrate 10 g / L and phosphorous acid 5 g / L at a temperature of 30 ° C., a treatment time of 45 seconds, and a pH of 2.0. The second treatment after washing with water is phosphoric acid. Using an aqueous solution of 9 g / L chromium and 8 g / L malonic acid, the temperature was 40 ° C., the treatment time was 10 seconds, and the pH was 4.0. The trivalent chromium white chemical conversion treatment was performed using an aqueous solution containing chromium nitrate 20 g / L, oxalic acid 15 g / L, and cobalt nitrate 3 g / L at a temperature of 30 ° C. and a treatment time of 40 seconds.

I Change of plating bath composition and appearance of plating and appearance of trivalent chromium black conversion coating treatment Appearance after plating and appearance after post-treatment by changing zinc, iron, alkali hydroxide, chelating agent, quaternary ammonium polymer and gluconic acid The corrosion resistance was evaluated. The appearance was comprehensively evaluated including gloss, uniformity, and black aesthetic after post-treatment. For the corrosion resistance, a salt spray test according to JIS Z 2371 was performed, and the time when red rust occurred was shown in the test results. The corrosion resistance test was terminated after 1500 hours, the absence of red rust was evaluated as ○, the occurrence of red rust at 1000 to 1500 hours as Δ, and the occurrence of red rust as less than 1000 hours as ×.

When a quaternary ammonium polymer and gluconic acid are added, a zinc-iron alloy plating film excellent in appearance and corrosion resistance can be obtained with a plating solution having a lower concentration than in the conventional case as in Reference Examples 1-15.

When Comparative Example 1 is seen, without the quaternary ammonium polymer and gluconic acid, the low concentration plating solution as in the Reference Example shows only insufficient appearance and corrosion resistance. Comparative Example 2 is a conventional standard zinc-iron alloy plating, which has a somewhat good appearance and corrosion resistance although it does not reach the reference example . Conversely, when a quaternary ammonium polymer and gluconic acid are added to a high concentration plating solution as in Comparative Example 2, the appearance and corrosion resistance of the coating deteriorate (Comparative Example 3). Comparative Examples 4 to 13 are test examples with a bath composition greatly deviating from Reference Example 1, and no satisfactory results are obtained.

Barrel plating was performed using the plating solutions of Reference Examples 1 to 15 and Comparative Examples 1 to 12, and the results were the same as those for stationary plating.

II Current density
The difference in applicable current density is large between Reference Example 1 and Comparative Example 2. When the appearance (especially the presence or absence of kogation) when performing static plating with varying current density is compared, the results shown in the table below are obtained. In the present invention, the upper limit of the applicable current density is increased by 2 to 3 times. There is.

III Film thickness, iron eutectoid rate For some reference examples and comparative examples, 100 copper plates of the same size as the iron plate were plated, and the iron eutectoid rate during plating was measured. The results were as follows. . The film thickness and the iron eutectoid rate were measured by using FISCHER SCOPE X-RAY XDLM-C4 manufactured by FISCHER.

In Reference Examples 1 to 5, all were satisfactory results in film thickness and iron eutectoid rate. However, the variation in Comparative Example 1 is larger than that in the Reference Example, and in Comparative Example 2, the variation is larger than that in Comparative Example 1, but the variation is larger than that in Reference Example 1.

IV Chromium black conversion coating test
The plated product of Reference Example 1 was subjected to a non-chrome black chemical conversion film treatment test.
Unless otherwise specified, phosphorous acid was used as the oxo acid of phosphorus, yttrium nitrate (comparative example 15 was yttrium sulfate) as the yttrium source, tin sulfate as the tin source, and vanadic acid as the vanadium source. The processing conditions are pH 1.8, temperature 30 ° C., and processing time 40 seconds. After chemical conversion treatment and washing with water, FT-170 manufactured by Nippon Surface Chemical Co., Ltd. was used as a post-treatment agent under standard conditions. The pH of the treatment solution was adjusted using nitric acid (comparative example 15 was sulfuric acid) and sodium hydroxide. The appearance was evaluated visually, with a uniform and glossy appearance as ◯, an appearance with some unevenness, cloudiness or lack of black, and an appearance with poor unevenness or cloudiness or almost no black. For the evaluation of corrosion resistance, a salt spray test according to JIS Z 2371 was performed, and the time when white rust was generated by 5% was shown in the test results.

  The results are shown in Table 4 below.

  The test was conducted by changing the conditions of immersion in the non-chromium black chemical conversion film treatment liquid having the bath composition of Example 16. The results are shown in Table 5 below.

V Others Reference examples were created under the conditions shown in the table below. In the following reference examples , all conditions not specifically described in the content column are the same as those in Reference Example 1. The evaluation method is the same as I.

A reference example was created under the conditions shown in the table below. The evaluation method is the same as IV.

VI Supplementary materials Below are some photographs of iron plates that were actually processed for some reference examples and comparative examples (Fig. 1). This is considered to be a document for confirming the superiority of the appearance of the metal member plated with the present invention and treated with the black chemical conversion film.

Claims (4)

A film forming method comprising:
An aqueous solution containing 8 to 16 g / L of zinc ions, 0.08 to 0.30 g / L of iron ions, 40 to 65 g / L of hydroxide ions, and 10 to 30 g / L of a chelating agent is further added to quaternary. 0.2-5 g / L of ammonium polymer, 0.1-5 g / L of one or more selected from divalent or higher polyvalent carboxylic acid, oxycarboxylic acid, aminocarboxylic acid or salts thereof Plating with a zinc-iron alloy plating solution ,
A step of performing a non-chrome black chemical conversion film treatment after the step,
Including
The treatment liquid for applying the non-chromium black chemical conversion film treatment,
1-100 g / L of phosphite ion,
0.1-30 g / L of nitrate ion,
2-100 mg / L of yttrium ions in the form of inorganic acid and yttrium salt,
10 to 550 mg / L tin, and
0.01-10 g / L of vanadium,
Including
The non-chrome black conversion coating treatment
pH 1.0-3.0,
Immersion time 20-120 seconds
The method performed in. The film forming method according to claim 1, wherein the chelating agent according to claim 1 is one or more selected from amino alcohols, tertiary or lower polyamines, polyhydric alcohols, and thioureas. 3. A film forming method, wherein after the non-chromium black film forming process according to claim 1 or 2 , a dipping process is performed once or a plurality of times with a second processing liquid. The metal base material which formed the non-chrome chemical conversion film using the method of any one of Claims 1-3 .