JP4471305B2 - Trivalent chromate treatment method and trivalent chromate solution additive - Google Patents

Description

The present invention relates to a trivalent chromate treatment method and a trivalent chromate liquid additive.

  When a coating having corrosion resistance was formed using a trivalent chromate solution after galvanization, there was no method for suppressing the elution of metal materials not covered with zinc plating in the chromate solution as ions. In the conventional hexavalent chromate solution, chromic acid acts as a corrosion inhibitor, making it difficult to corrode iron and the like, so that it was not necessary to use a corrosion inhibitor.

  However, since hexavalent chromate is harmful, a trivalent chromate solution has been developed instead. Although the trivalent chromate solution has a function of forming a corrosion-resistant film on galvanizing, the pH is about 2, so that the metal material such as iron of the material to be treated that is not coated with galvanizing is dissolved as ions. Resulting in. The conventional trivalent chromate liquid composition has no effect of suppressing metal dissolution, and the chromate liquid has a short life. Hereinafter, conventional problems will be described in detail.

  As conventional methods, there are a metal surface treatment agent, a metal surface treatment liquid, a corrosion-resistant colored film formed thereby, a corrosion-resistant colored part having this corrosion-resistant colored film, and a method for producing this corrosion-resistant colored part (Patent Document 1). . This method does not use hexavalent chromium or a fluorine compound, and provides a colored film having an excellent color tone and appearance that has the same or higher corrosion resistance than the conventional chromate treatment using hexavalent chromium. However, there is no effect of suppressing dissolution of a metal material such as iron while maintaining the function of forming a corrosion-resistant film after galvanization using a commercially available trivalent chromate solution.

  Further, a concentrated liquid composition for surface chemical conversion treatment with hexavalent chromium having improved stability (Patent Document 2) has been proposed. This is a concentrate composition for chemical conversion treatment represented by trivalent chromate treatment excellent in storage stability, in which gas generation is not observed when a concentrate containing chromium ions, organic acid and nitric acid is stored. However, there is no disclosure of a function of suppressing dissolution of a metal material such as iron while maintaining a function of forming a corrosion-resistant film after galvanization.

  A method of forming a hexavalent chromium-free corrosion-resistant film on a trivalent chromate solution and zinc-nickel alloy plating using the same is also proposed (see Patent Document 3). This only discloses a method of forming a trivalent chromate film having high corrosion resistance by using a trivalent chromate solution on zinc-nickel alloy plating, and after the desired zinc plating, a corrosion resistant film is disclosed. This is not to suppress dissolution of a metal material such as iron while maintaining the function to be formed.

  In the finishing composition for a trivalent chromate film and the method for finishing a trivalent chromate film disclosed in Patent Document 4, a chelating agent is used. A composition and method for obtaining a trivalent chromate film having low insulation, no problem in screw tightening performance, excellent gloss and high corrosion resistance are disclosed, and the corrosion resistance after galvanization is disclosed. There is no disclosure about the point of suppressing dissolution of metal materials such as iron while maintaining the function of forming a certain film.

Further, in the resin chromate bath and surface-treated steel sheet disclosed in Patent Document 5 (see Patent Document 5), a resin chromate having an excellent bath life and a film excellent in corrosion resistance, paint adhesion, and chromium elution resistance are provided. A surface-treated steel sheet has been proposed, but the composition of the bath contains hexavalent chromium ions as chromic acid, and does not solve the conventional problems.
JP-A-2005-187925 JP 2005-179702 A JP-A-2005-126797 JP2005-23372 JP-A-9-165686

  That is, as a trivalent chromate solution, it has been studied to obtain a film having low insulation, good screw tightening, excellent gloss and high corrosion resistance, paint adhesion, and chromium elution resistance. However, it has not been studied to extend the life of the liquid. The components of the trivalent chromate liquid are mainly composed of chromium chloride, chromium nitrate and the like, and are more expensive than the chromic acid of the hexavalent chromate liquid that has been widely used before that. In addition, since the life of the liquid is reduced to half or less than that of the hexavalent chromate liquid, the chromating cost is inevitably increased.

  The main cause of the decrease in the liquid life is that the corrosion-resistant film cannot be formed by increasing the iron concentration of impurities. Iron is used in galvanized materials. By galvanizing, the normal surface of the member to be treated is covered with zinc. However, for example, the inside of the pipe, the inside of the contact between the plate and the plate by pressing is not covered with zinc, and the iron base is exposed as it is. Therefore, when the member to be treated is immersed in a trivalent chromate solution, the iron on the surface dissolves as ions, so that the life of the solution is reduced.

The present invention uses a commercially available trivalent chromate solution to maintain the function of forming a corrosion-resistant film after galvanization, while suppressing the dissolution of metal materials such as iron and extending the life of the chromate solution. And a trivalent chromate treatment method and a trivalent chromate liquid additive.

  In order to achieve the above object, the present invention has the following characteristic configuration.

(1) In a trivalent chromate treatment method performed on a metal material to be treated which is at least partially galvanized,
A trivalent chromate treatment method in which a chromate liquid contains an additive (excluding pyrazole and glutamic acid) that suppresses dissolution of the metal material to be treated.
(2) An additive to a trivalent chromate solution for immersing the metal material to be treated in order to perform a trivalent chromate treatment on the metal material to be treated which is at least partially galvanized,
A trivalent chromate solution additive that has an effect of suppressing dissolution of the metal material to be treated during trivalent chromate treatment on the surface of the metal material to be treated which is not galvanized.
(3) The trivalent chromate treatment method according to the above (1), wherein at least one of an organic compound having a cyclic structure, an unsaturated compound, a nitrogen compound, a hydroxyl group, and a carboxyl group is used as the additive.
(4) The above-mentioned additive includes (A) a drug having a molecular structure of a pyrazolyl group which is a cyclic hydrocarbon compound, or a phenyl group having one or more functional groups, (B) an aliphatic saturated hydrocarbon compound or unsaturated Drug having one or more functional groups of methyl group or vinylene group as hydrocarbon compound, (C) One or more functional groups of amino group, triazinyl group, or triazolyl group as hydrocarbon compound containing nitrogen Or (D) any one of the above (1) or (3), which comprises (D) at least one of a drug having one or more functional groups of a hydroxyl group or a carboxyl group as a hydrocarbon compound containing oxygen Trivalent chromate treatment method.
(5) The hydrocarbon compound having the functional group is pyrazole-3,5-dicarboxylic acid monohydrate, 4-aminoantipyrine, 5-aminopyrazole-4-carbonitrile, bispyrazolone, 3,5-dimethylpyrazole , Ethyl 3-aminopyrazole-4-carboxylate, 1-phenyl-3-methyl-5-pyrazolone, 3-methylpyrazole, 1-phenyl-3-pyrazolidinone, 1-phenylpyrazole, cinnamaldehyde, cinnamic acid, chloride Cinnamoyl, cinnamonitrile, cinnamyl alcohol, benzyl cinnamate, 3-chlorocinnamic acid, 4-chlorocinnamic acid, 3,4-dihydrocinnamic acid, 4- (dimethylamino) -cinamaldehyde, ethyl cinnamate , Ethyl 3-phenylpropionate, ethyl 4-nitrocinnamate, 4-fluorosilicate Acid, 3-hydroxy-4-methoxycinnamic acid, 4-hydroxycinnamic acid, t-3-methoxycinnamic acid, methyl cinnamate, α-methylcinnamaldehyde, α-methylcinnamic acid, 4-methylcinnamic acid Acid, 2′-nitrocinnamaldehyde, 2′-nitrocinnamic acid, 3′-nitrocinnamic acid, 4′-nitrocinnamic acid, methylisoeugenol, t-anethole, eugenol, 3-methyl-3-butene-1- All, 1,2,3-benzotriazole, 3,5-diamino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-nitro-1H-1,2,4-triazole 4-phenylurazole, 1,2,4-triazole, 1H-1,2,4-triazole sodium salt, 3-amino-5-mercapto-1,2,4-triazol , 3-amino-5- (methylmercapto) -1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-1,2,4-triazole, itacon The trivalent chromate treatment method according to the above (4), which comprises at least one of acid, anthranilic acid, and ethylene glycol.
(6) The additive amount of the additive added to the trivalent chromate solution is 0.001% or more and 10% or less, 3 of any of (1), (3), (4) or (5) above Chromate treatment method.

That is, when a corrosion inhibitor is adsorbed on a metal surface, adsorption occurs when immersed in a solution, and when a metal surface such as iron is covered with a corrosion inhibitor, the rate of ions eluted from the metal does not depend on the passage of time. does not change. On the other hand, if the adsorption occurs gradually after being immersed in the solution and the metal surface is covered, the speed of the ions eluted from the metal is because the metal ions are eluted from the place not initially covered with the corrosion inhibitor, The elution rate is high in the initial stage, and the elution rate gradually decreases with time. Since the chromate time is usually about 30 to 60 seconds, a chemical is used in which adsorption takes place in a short time when immersed in a solution and the metal surface is covered with a corrosion inhibitor. As the corrosion inhibitor, at least one of an organic compound having a cyclic structure, an unsaturated compound, a nitrogen compound, a hydroxyl group, and a carboxyl group is used.

  The present invention suppresses the elution of the plating material into the chromate solution while maintaining the function of forming a corrosion-resistant film when the zinc plating chromate solution is used. By utilizing the effect of the dissolved corrosion inhibitor, it is possible to reduce the impurity accumulation rate of the chromate liquid by suppressing the elution of iron materials such as the inner surface of pipes that are not coated with zinc plating into the chromate liquid. We are trying to extend the service life.

  According to the present invention, it is possible to suppress dissolution of a metal material such as iron while maintaining the function of forming a corrosion-resistant film during the trivalent chromate treatment after galvanization. Moreover, the corrosion inhibitor to be used can be utilized at the pH and operating temperature required for maintaining and managing a commercially available trivalent chromate solution.

  In addition, the present invention requires only a small addition of a corrosion inhibitor to a commercially available chromate solution having a function of forming a corrosion-resistant film during the trivalent chromate treatment after galvanization, and can be used without changing the use conditions. it can. Since trivalent chromate treatment extends the life, the amount of waste liquid is reduced and surface treatment in harmony with the environment becomes possible.

Examples of the present invention will be described below.
(Characteristics of trivalent chromate and conditions for corrosion inhibitors)
As a corrosion inhibitor, it is best to add in advance to a commercially available trivalent chromate solution and to carry out the same steps as in normal operations. Since a commercially available trivalent chromate solution has a pH of about 2, a corrosion inhibitor that has an acidity of about pH 2 and does not precipitate and exhibits a corrosion inhibiting effect is selected. The trivalent chromate solution contains oxalic acid, malonic acid, citric acid, tartaric acid, malic acid, silicic acid or its salts as chelating agents. To do. It is also necessary that the working temperature can be maintained at the specified temperature of 30 ° C. to 60 ° C. and the corrosion inhibition effect can be maintained.

(Criteria for selecting a corrosion inhibitor for longer life)
Functional groups that can be used as corrosion inhibitors include those having a pyrazolyl group that is a cyclic hydrocarbon compound, such as pyrazole, pyrazole-3,5-dicarboxylic acid monohydrate, 4-aminoantipyrine, 5-amino Pyrazole-4-carbonitrile, bispyrazolone, 3,5-dimethylpyrazole, ethyl 3-aminopyrazole-4-carboxylate, 1-phenyl-3-methyl-5-pyrazolone, 3-methylpyrazole, 1-phenyl-3 -Pyrazolidinone, 1-phenylpyrazole. Some have a phenyl group which is a cyclic hydrocarbon compound, such as 1-phenylpyrazole, methyl cinnamate, and cinnamic acid. There are those having a methyl group which is an aliphatic saturated hydrocarbon compound, such as 1-phenyl-3-methyl-5-pyrazolone and methyl cinnamate. There are those having a vinylene group which is an unsaturated hydrocarbon compound, such as cinnamaldehyde, cinnamic acid, cinnamoyl chloride, cinnamonitrile, cinnamyl alcohol, benzyl cinnamate, 3-chlorocinnamic acid, 4-chlorocinnamic Acid, 3,4-dihydrocinnamic acid, 4- (dimethylamino) -cinamaldehyde, ethyl cinnamate, ethyl 3-phenylpropionate, ethyl 4-nitrocinnamate, 4-fluorocinnamic acid, 3-hydroxy -4-methoxycinnamic acid, 4-hydroxycinnamic acid, t-3-methoxycinnamic acid, methyl cinnamate, α-methylcinnamaldehyde, α-methylcinnamic acid, 4-methylcinnamic acid, 2′- Nitrocinnamaldehyde, 2′-nitrocinnamic acid, 3′-nitrocinnamic acid, 4′-nitrocinnamic acid, methyl isoeugenol, - anethole, eugenol, 3-methyl-3-buten-1-ol. Some have an amino group which is a hydrocarbon compound containing nitrogen, such as anthranilic acid and glutamic acid. Further, there are those having a triazinyl group and a triazolyl group, which are hydrocarbon compounds containing nitrogen, for example. 1,2,3-benzotriazole, 3,5-diamino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-nitro-1H-1,2,4-triazole, 4 -Phenylurazole, 1,2,4-triazole, 1H-1,2,4-triazole sodium salt, 3-amino-5-mercapto-1,2,4-triazole, 3-amino-5- (methyl mercapto) ) -1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-1,2,4-triazole. Some have a hydroxyl group, which is a hydrocarbon compound containing oxygen, such as ethylene glycol. Some have a carboxyl group, which is a hydrocarbon compound containing oxygen, such as itaconic acid, anthranilic acid, cinnamic acid, and glutamic acid.

Examples of hydrocarbon compounds having a corrosion inhibitor function include pyrazole-3,5-dicarboxylic acid monohydrate, 4-aminoantipyrine, 5-aminopyrazole-4-carbonitrile, bispyrazolone, 3,5-dimethylpyrazole, 3, -Ethyl aminopyrazole-4-carboxylate, 1-phenyl-3-methyl-5-pyrazolone, 3-methylpyrazole, 1-phenyl-3-pyrazolidinone, 1-phenylpyrazole, cinnamaldehyde, cinnamic acid, cinnamoyl chloride, Cinnamonitrile, cinnamyl alcohol, benzyl cinnamate, 3-chlorocinnamic acid, 4-chlorocinnamic acid, 3,4-dihydrocinnamic acid, 4- (dimethylamino) -cinamaldehyde, ethyl cinnamate, 3 -Ethyl phenylpropionate, ethyl 4-nitrocinnamate, 4-fluoroke Cinnamic acid, 3-hydroxy-4-methoxycinnamic acid, 4-hydroxycinnamic acid, t-3-methoxycinnamic acid, methyl cinnamate, α-methylcinnamaldehyde, α-methylcinnamic acid, 4-methylcinnamic acid Cinamic acid, 2'-nitrocinnamaldehyde, 2'-nitrocinnamic acid, 3'-nitrocinnamic acid, 4'-nitrocinnamic acid, methylisoeugenol, t-anethole, eugenol, 3-methyl-3-butene-1 -Ol, 1,2,3-benzotriazole, 3,5-diamino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-nitro-1H-1,2,4- Triazole, 4-phenylurazole, 1,2,4-triazole, 1H-1,2,4-triazole sodium salt, 3-amino-5-mercapto-1,2,4-triazo 3-amino-5- (methylmercapto) -1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-1,2,4-triazole, One or more of itaconic acid, anthranilic acid, and ethylene glycol are used.

  The addition amount of the corrosion inhibitor is preferably 0.001% or more and 10% or less, and the corrosion resistance of the chromate film obtained by the trivalent chromate treatment is white rust generated within at least 6 to 96 hours in the salt spray test. Select a corrosion inhibitor that can maintain the function of forming a non-performing film.

Corrosion inhibitors are not specified as poisonous, deleterious, or harmful substances under the Poisonous and Deleterious Substances Control Law, and are also dangerous goods as defined in Schedule 4 of the Dangerous Goods Regulations Notification by the Fire Service Act, and Those that do not fall under any of the flammable materials are desirable . In addition, if one that does not produce a malignant chemical odor is selected, it can be harmonized with the environment.

In the present invention, in the trivalent chromate treatment step performed after galvanization, the metal surface is covered with the corrosion inhibitor when the material to be chromated is immersed. In order to confirm the effect of extending the life of the trivalent chromate solution additive of the present invention, the following experiment was conducted. For example, using 2 ml of Nihon Surface Chemical Co., Ltd. TR-175 having a liquid temperature of 30 ° C. as a chromate solution, a 0.6 mm diameter iron wire immersed in 1% nitric acid for 10 seconds in advance and then washed with water has a surface area of 2 cm. ^{It was} immersed in ² and stirred with a stirrer. In order to determine the corrosion rate of iron, 0.025 ml of the solution was taken every 10 seconds. To the collected solution, 0.07 ml of 10% hydroxylammonium hydrochloride, 0.07 ml of pH 4.3 buffer solution and 0.07 ml of 1% o-phenanthroline hydrochloride were added to make 2.5 ml with water, and the absorbance at 510 nm was measured. The elution concentration of iron was determined.

  FIG. 1 is a diagram showing the corrosion rate of iron when 1,2,3-benzotriazole is added. FIG. 2 is a diagram showing the corrosion rate of iron when 1-phenylpyrazole and methyl cinnamate are added.

FIG. 1 shows the result of using Nippon Surface Chemical Co., Ltd. TR-175 as the chromate solution and 1,2,3-benzotriazole as the corrosion inhibitor. The elution concentration varies due to stirring and has a repeat error of 20 to 30%. However, when the amount of corrosion inhibitor added is less than 0.1% indicated by ◆ and ■ and when the amount added is 0.3 to 0.5% indicated by ○, ×, ●, the iron elution concentration is repeated. There is a difference greater than the error. When the corrosion inhibitor concentration is low, the value of the approximate Y-axis intercept is about 14, and when the corrosion inhibitor concentration is high 0.4%, it is about 8. In both cases, the coefficient of determination of the approximate line (R ² : the square value of the correlation coefficient) is close to 1. If it takes a long time for the corrosion inhibitor to adsorb, the iron elution rate immediately after immersion should be high and the deviation from the approximate line should be large. However, the tendency is slight and is about 10 to 20% of the iron elution amount after 30 seconds of chromate treatment.

  From this, it is considered that adsorption occurs for several seconds immersed in the solution, and the iron surface is covered with the corrosion inhibitor. It can also be seen that a concentration of 1,2,3-benzotriazole of 0.3 to 0.5% is sufficient to obtain the effect of the corrosion inhibitor.

  In order to confirm the effect of adding a hydrocarbon compound having a corrosion inhibitor function, an experiment was conducted using Nippon Surface Chemistry Co., Ltd. TR-175 as a chromate solution. In FIG. 2, the ■ indicates the corrosion-inhibiting effect when 0.3% 1-phenylpyrazole is added, and ◆ indicates 0.01% methyl cinnamate. In FIG. 3, x indicates the effect of adding 0.03% methyl cinnamate.

  4 shows the corrosion rate of iron when itaconic acid is added, FIG. 5 shows the corrosion rate of iron when anthranilic acid is added, and FIG. 6 shows the corrosion rate of iron when ethylene glycol and sodium glutamate are added. FIG.

  The circles in FIG. 4 indicate the effect of adding 0.3% itaconic acid. In FIG. 5, x indicates the effect of adding 0.3% anthranilic acid. In FIG. 6, 0.2% 1,2,3-benzotriazole is added in advance, 0.2% ethylene glycol is added, and 0.2% sodium glutamate is added. Indicated. Any of these hydrocarbon compounds has a corrosion-inhibiting effect.

  In order to confirm the corrosion inhibition effect of iron in various commercial products, it was examined in Example 2 whether 1-phenylpyrazole, which had a high iron corrosion inhibition effect, was effective in inhibiting iron corrosion of other commercially available trivalent chromate solutions. As a commercially available trivalent chromate solution, TR-173 manufactured by Nippon Surface Chemistry Co., Ltd., TRIVALENT300 manufactured by Ebara Eugene Corporation, TRIVALENT600, YFA manufactured by Yuken Industry Co., Ltd., and C-8000 manufactured by Aiko Chemical Co., Ltd. were examined. The results are shown in FIG. Although TR-175 manufactured by Nippon Surface Chemical Co., Ltd. overlaps, it is listed because it is easy to compare with other commercially available products. According to the specifications, the liquid temperature was 40 ° C. for C-8000 manufactured by Aiko Chemical Co., Ltd., 60 ° C. for TRIVALENT 600 manufactured by Sugawara Eugelite Co., Ltd., and 30 ° C. for others.

FIG. 7 is a diagram showing the corrosion rate of iron in a solution obtained by adding 0.3% 1-phenylpyrazole to various commercially available products and a solution containing no additive.
In FIG. 7, numerals and symbols indicate the following.
173: TR-173 manufactured by Nippon Surface Chemical Co., Ltd.
175: TR-175 manufactured by Nippon Surface Chemistry Co., Ltd.
300: TRIVALENT300 manufactured by Sugawara Eugene Corporation
600: TRIVALENT600 manufactured by Sugawara Eugelite Co., Ltd.
YFA: YFA manufactured by Yuken Industry Co., Ltd.
8000: Aiko Chemical Co., Ltd. C-8000

  In FIG. 7, Δ indicates only a commercially available product, and ■ indicates that 0.3% 1-phenylpyrazole is added. When a corrosion inhibitor is added as compared with a commercially available product, TR-173 manufactured by Nippon Surface Chemical Co., Ltd. is 1 / 1.6, and TR-175 manufactured by Nippon Surface Chemical Co., Ltd. is 1 / 1.7. In addition, 300 manufactured by Ebara Eugene Light Co., Ltd. is reduced to 1 / 3.5, TRIVALENT 600 manufactured by Ebara Eugene Lite Co., Ltd. is converted to 1 / 1.3, YFA manufactured by Yuken Industry Co., Ltd. is converted to 1 / 2.9. Chemical Co., Ltd. C-8000 has an effect of reducing the iron elution amount to 1 / 2.4.

  In order to confirm that the chromate film treated by adding a corrosion inhibitor has corrosion resistance in the JIS H8502 salt spray test, 0.3% 1-phenylpyrazole was added to TR-173 and TR-175 manufactured by Nippon Surface Chemical Co., Ltd. Prepare a solution containing only the product and a commercially available solution, and apply 5 micron zinc to an iron test piece cut out to 5 x 5 cm, immerse in 1% nitric acid for 10 seconds, wash with water, and add a corrosion inhibitor. Each of the liquid and the commercially available liquid was brought to 30 ° C. and chromated for 45 seconds. No difference in appearance was observed between the specimens with chromate treatment and those with or without the addition of a corrosion inhibitor. Each test piece obtained was subjected to a salt spray test for 96 hours. After the salt spray test, neither white rust nor red rust was observed.

It is a figure which shows the corrosion rate of iron at the time of 1,2,3-benzotriazole addition. It is a figure which shows the corrosion rate of iron at the time of 1-phenylpyrazole and methyl cinnamate addition. It is a figure which shows the corrosion rate of iron at the time of methyl cinnamate addition. It is a figure which shows the corrosion rate of iron at the time of itaconic acid addition. It is a figure which shows the corrosion rate of iron at the time of anthranilic acid addition. It is a figure which shows the corrosion rate of iron at the time of addition of ethylene glycol and sodium glutamate. It is a figure which shows the corrosion rate of the iron in the liquid which added 0.3% 1-phenylpyrazole to various commercial items, and an additive-free liquid.

Explanation of symbols

173: TR-173 manufactured by Nippon Surface Chemical Co., Ltd.
175: TR-175 manufactured by Nippon Surface Chemistry Co., Ltd.
300: TRIVALENT300 manufactured by Sugawara Eugene Corporation
600: TRIVALENT600 manufactured by Sugawara Eugelite Co., Ltd.
YFA: YFA manufactured by Yuken Industry Co., Ltd.
8000: Aiko Chemical Co., Ltd. C-8000
Δ: Each commercial product only ■: 0.3% 1-phenylpyrazole added to each commercial product

Claims (6)

In a trivalent chromate treatment method performed on a metal material to be treated which is at least partially galvanized,
A trivalent chromate treatment method, wherein a chromate solution contains an additive (excluding pyrazole and glutamic acid) that suppresses dissolution of the metal material to be treated. An additive to a trivalent chromate solution for immersing the metal material to be treated in order to perform a trivalent chromate treatment on the metal material to be treated which is at least partially galvanized,
A trivalent chromate solution additive characterized by giving an effect of suppressing dissolution of the metal material to be treated during trivalent chromate treatment on the surface of the metal material to be treated which is not galvanized.   The trivalent chromate treatment method according to claim 1, wherein at least one of an organic compound having a cyclic structure, an unsaturated compound, a nitrogen compound, a hydroxyl group, and an organic compound having a carboxyl group is used as the additive. .   The additive in the preceding paragraph is (A) a drug having a molecular structure of a pyrazolyl group which is a cyclic hydrocarbon compound, or a phenyl group having one or more functional groups, (B) an aliphatic saturated hydrocarbon compound or an unsaturated hydrocarbon compound A drug having one or more functional groups of methyl group or vinylene group, and (C) a drug having one or more functional groups of amino group, triazinyl group, or triazolyl group as a hydrocarbon compound containing nitrogen (D) It contains at least 1 chemical | medical agent among the chemical | medical agents which have the hydroxyl group or the functional group of the carboxyl group as a hydrocarbon compound in which oxygen is contained in any one of Claim 1 or 3 characterized by the above-mentioned. A trivalent chromate treatment method.   The hydrocarbon compound having the functional group is pyrazole-3,5-dicarboxylic acid monohydrate, 4-aminoantipyrine, 5-aminopyrazole-4-carbonitrile, bispyrazolone, 3,5-dimethylpyrazole, 3- Ethyl aminopyrazole-4-carboxylate, 1-phenyl-3-methyl-5-pyrazolone, 3-methylpyrazole, 1-phenyl-3-pyrazolidinone, 1-phenylpyrazole, cinnamaldehyde, cinnamic acid, cinnamoyl chloride, syn Namonitrile, cinnamyl alcohol, benzyl cinnamate, 3-chlorocinnamic acid, 4-chlorocinnamic acid, 3,4-dihydrocinnamic acid, 4- (dimethylamino) -cinamaldehyde, ethyl cinnamate, 3- Ethyl phenylpropionate, ethyl 4-nitrocinnamate, 4-fluorocinnamic acid, -Hydroxy-4-methoxycinnamic acid, 4-hydroxycinnamic acid, t-3-methoxycinnamic acid, methyl cinnamate, α-methylcinnamaldehyde, α-methylcinnamic acid, 4-methylcinnamic acid, 2 '-Nitrocinnamaldehyde, 2'-nitrocinnamic acid, 3'-nitrocinnamic acid, 4'-nitrocinnamic acid, methylisoeugenol, t-anethole, eugenol, 3-methyl-3-buten-1-ol, 1 , 2,3-benzotriazole, 3,5-diamino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-nitro-1H-1,2,4-triazole, 4- Phenylurazole, 1,2,4-triazole, 1H-1,2,4-triazole sodium salt, 3-amino-5-mercapto-1,2,4-triazol 3-amino-5- (methylmercapto) -1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-1,2,4-triazole, itaconic acid 5. The method for treating trivalent chromate according to claim 4, comprising at least one of anthranilic acid and ethylene glycol.   The trivalent chromate treatment according to any one of claims 1, 3, 4 and 5, wherein an additive amount of the additive added to the trivalent chromate liquid is 0.001% or more and 10% or less. Method.

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