Copper adhesion inhibitors, copper adhesion inhibiting pickling solutions, and pickling methods for pickling steel materials.

Abstract

This invention provides a copper adhesion inhibitor that inhibits copper adhesion to steel materials and suppresses the deterioration of the color tone of the steel material surface when pickling steel materials in a hydrochloric acid cleaning solution containing a large amount of copper ions. [Solution] A copper adhesion inhibitor for addition to a pickling solution for steel materials, characterized by comprising one or more of the following: polyallylamine, diallylamine-sulfur dioxide copolymer or a salt thereof, methyldiallylamine-sulfur dioxide copolymer or a salt thereof, dialkyldiallylammonium-sulfur dioxide copolymer, polycondensate of dicyandiamide and diethylenetriamine or a salt thereof.

Description

[Technical Field]

[0001] The present invention relates to a copper adhesion inhibitor that inhibits the adhesion of copper to the surface of steel produced by a steelmaking method using scrap materials as raw materials (for example, an electric furnace steelmaking method), a copper adhesion inhibiting acid pickling solution obtained by adding the copper adhesion inhibitor to a hydrochloric acid pickling solution, and an acid pickling method using the copper adhesion inhibiting acid pickling solution. [Background technology]

[0002] Hot-rolled steel sheets are generally pickled with hydrochloric acid after hot rolling, primarily for the purpose of removing scale that has formed on the surface of the steel sheet during hot rolling, i.e., descaling. However, in steelmaking methods that use scrap materials as raw materials (for example, electric furnace steelmaking), the copper concentration in the steel and its scale is higher than in steelmaking methods that do not use scrap materials because the scrap material contains copper as an impurity. During pickling, copper ions dissolve into the acid solution, and the concentration of copper ions in the hydrochloric acid washing solution increases. When pickling is performed with hydrochloric acid with an increased copper ion concentration, copper reattachment occurs to the steel. This is thought to be because, during washing with hydrochloric acid containing copper ions, copper is deposited on the surface of the steel through a substitution reaction with iron. Since the appearance deteriorates due to the adhesion of copper, washing with hydrochloric acid containing copper ions is a factor in reducing yield. This tendency is particularly pronounced in acid solutions containing 20 ppm or more of copper ions. As a result, copper adheres to the surface of the steel, worsening its color.

[0003] Therefore, methods have been proposed to improve the color tone by adding nitric acid to the pickling bath, and to pickle using an ultrasonic vibration device or jet device to improve the color tone and suppress the Cu substitution deposition reaction on the steel plate surface during pickling (Patent Document 1). However, adding nitric acid to the pickling solution is not sufficient to suppress copper adhesion to the steel surface, and installing an ultrasonic vibration device or jet device in the pickling line presents problems such as the complexity of the equipment and the need for maintenance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-2919 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a copper adhesion inhibitor that inhibits the adhesion of copper to the surface of steel produced by a steelmaking method using scrap materials as raw materials (for example, electric furnace steelmaking method), thereby contributing to the reduction of discoloration and improvement of yield of the steel; a copper adhesion inhibiting acid pickling solution obtained by adding the copper adhesion inhibitor to a hydrochloric acid pickling solution; and an acid pickling method using the copper adhesion inhibiting acid pickling solution. [Means for solving the problem]

[0006] The present invention is a copper adhesion inhibitor to be added to an acid cleaning solution for steel materials, characterized by containing one or more compounds or salts thereof of any of the following general formulas (1) to (4). [ka] (In the general formula (1) above, n represents the repeating unit.) [ka] (In the general formula (2) above, n represents a repeating unit, and R1 is one of hydrogen, a methyl group, or an ethyl group.) [ka] (In the above general formula (3), n represents a repeating unit, and R1 and R2 are either a methyl group or an ethyl group, and may be the same group or different groups. X - (This is a counterion.) [ka] (In the general formula (4), n represents a repeating unit.)

[0007] Further, the present invention is a copper deposition-inhibiting pickling solution characterized by containing the copper deposition inhibitor and an aqueous hydrochloric acid solution.

[0008] The copper deposition-inhibiting pickling solution of the present invention is further characterized by containing copper ions.

[0009] The copper deposition-inhibiting pickling solution of the present invention is characterized in that the concentration of the copper ions is 20 ppm or more.

[0010] The copper deposition-inhibiting pickling solution of the present invention is characterized by containing 5 to 3000 mg / L of the copper deposition inhibitor.

[0011] Further, the present invention is a pickling method for steel materials, characterized by pickling the steel materials with the copper deposition-inhibiting pickling solution.

Effects of the Invention

[0012] The copper deposition inhibitor of the present invention can prevent the reduction of the color tone and the deterioration of the appearance of the pickled steel material by inhibiting copper deposition when pickling the steel material with hydrochloric acid containing copper ions, and can improve the quality and yield of the steel material. Further, the copper deposition-inhibiting pickling solution of the present invention containing the copper deposition inhibitor can be used for a longer period than conventional pickling solutions, and the frequency of replacement of the pickling solution can be reduced.

Modes for Carrying Out the Invention

[0013] The copper deposition inhibitor of the present invention is a copper deposition inhibitor added to a hydrochloric acid pickling solution of steel materials produced by a steelmaking method using scrap materials in the raw materials, and contains one or more compounds represented by the general formulas (1) to (4) or salts thereof, and is characterized by inhibiting copper deposition on the steel material during hydrochloric acid pickling.

[0014] In the present invention, specific polyamines are effective as copper adhesion inhibitors. Examples of effective polyamines as copper adhesion inhibitors include polyallylamine, diallylamine-sulfur dioxide copolymer, methyldiallylamine-sulfur dioxide copolymer, dialkyldiallylammonium-sulfur dioxide copolymer, polycondensates of dicyandiamide and diethylenetriamine or their salts. The salts are not particularly limited, but examples include inorganic salts such as hydrochloride salts and sulfate salts, or organic salts such as acetate salts, formate salts, citrate salts, malic acid salts, and succinate salts.

[0015] The polyallylamine is a polyamine represented by the following general formula (1), and its molecular weight is preferably 1,000 to 100,000, and more preferably 1,000 to 20,000. [ka] (In the general formula (1) above, n represents the repeating unit.)

[0016] The diallylamine-sulfur dioxide copolymer and the methyldiallylamine-sulfur dioxide copolymer are polyamines represented by the following general formula (2), and their molecular weight is preferably 1,000 to 100,000, and more preferably 1,000 to 20,000. [ka] (In the general formula (2) above, n represents a repeating unit, and R1 is one of hydrogen, a methyl group, or an ethyl group.)

[0017] The dialkyldiallylammonium sulfur dioxide copolymer is a salt of a polyamine represented by the following general formula (3), and its molecular weight is preferably 1,000 to 100,000, and more preferably 1,000 to 20,000. [ka] (In the above general formula (3), n represents a repeating unit, and R1 and R2 are either a methyl group or an ethyl group, and may be the same group or different groups. X - X is a counterion. - The anion can be any anion, and there are no other restrictions, but it is preferably an anion derived from an organic acid or inorganic substance. For example, Cl - , Br - , I - Examples include halogen ions such as methanesulfonate ions, ethanesulfonate ions, propanesulfonate ions, and other sulfonate ions, alkyl sulfate ions such as methyl sulfate ions, ethyl sulfate ions, and propyl sulfate ions, and acetate ions.

[0018] The polycondensate of dicyandiamide and diethylenetriamine is a polyamine represented by the following general formula (4), and its molecular weight is preferably 1,000 to 100,000, and more preferably 1,000 to 20,000. [ka] (In the general formula (4) above, n represents the repeating unit.)

[0019] The polyamines of the general formulas (1), (2), and (4) may also be in the form of salts. The salts are not particularly limited, but examples include inorganic salts such as hydrochloride and sulfate, or organic salts such as acetate, formate, citrate, malic acid, and succinate. One type may be used alone, or two or more types may be used in combination.

[0020] Furthermore, the copper adhesion inhibitor may be mixed with water to form a copper adhesion inhibitor. In this case, the mixing ratio of the copper adhesion inhibitor is preferably 0.5 to 100 parts by weight of the copper adhesion inhibitor per 100 parts by weight of water.

[0021] Furthermore, the copper adhesion inhibitor containing water may optionally contain surfactant components, pH adjusting agents, organic solvent components, and other components. The concentration of the mixture should be such that the total amount of each component is approximately 0.5 to 100 parts by weight per 100 parts by weight of water.

[0022] A mixture of copper adhesion inhibitor and water, or a mixture of copper adhesion inhibitor and water containing other components, can be used in actual treatment by further diluting this mixture to the desired concentration.

[0023] In this invention, the reason why a specific polyamine is suitably effective in inhibiting copper adhesion is not yet clear. However, it is believed that the suitable copper adhesion inhibitory effect is achieved through steric hindrance based on the structure and properties of the specific polyamine, as well as interactions with the steel material and copper ions. The copper adhesion inhibitor thus obtained in this invention can prevent the deterioration of color and appearance of steel materials due to copper adhesion after pickling, thereby improving the quality and yield of the steel material.

[0024] The copper adhesion inhibitor of the present invention can be mixed with an aqueous hydrochloric acid solution to form a copper adhesion inhibiting acid washing solution. The copper adhesion inhibiting acid washing solution may contain copper ions, and may contain copper ions at a concentration of 20 ppm or more. The copper adhesion inhibiting acid washing solution of the present invention can exert its effect even when the concentration of copper ions in the solution reaches 500 ppm.

[0025] The copper adhesion inhibiting acid cleaning solution of the present invention is preferably prepared by adding a copper adhesion inhibitor to an aqueous hydrochloric acid solution, which is obtained by dissolving hydrochloric acid suitable for cleaning steel materials in water, in a concentration of 5 to 3000 mg / L. More preferably, the amount of copper adhesion inhibitor added is 10 to 3000 mg / L, and even more preferably 30 to 3000 mg / L. The upper limit of the concentration of the copper adhesion inhibitor may be 3000 mg / L or higher, but considering the frequency of changing the hydrochloric acid cleaning solution, a concentration of 3000 mg / L is sufficient to exhibit a copper adhesion inhibiting effect.

[0026] In other words, the copper adhesion inhibitor of the present invention can be added to a hydrochloric acid washing solution to a concentration of 5 to 3000 mg / L and used as a copper adhesion inhibiting acid washing solution.

[0027] Acid pickling of steel materials can be performed using a continuous hydrochloric acid pickling facility. The pickling temperature for steel materials is generally 20 to 95°C, and the copper adhesion inhibitor of the present invention can be used stably within this temperature range.

[0028] The copper adhesion inhibitor of the present invention may be added to an aqueous hydrochloric acid solution before use, or it may be added to an aqueous hydrochloric acid solution in advance to form a pickling solution composition, which can then be used as is or diluted with water during pickling.

[0029] Furthermore, the copper adhesion inhibitor of the present invention and the copper adhesion inhibiting acid cleaning solution containing it are used for acid cleaning of steel materials, and the target metals include iron, carbon steel, alloy steel, and special steel. [Examples]

[0030] The present invention will be described in detail below with reference to examples and comparative examples, but the embodiments described above are merely illustrative in all respects, and the scope of the present invention is as set forth in the claims and is not bound in any way by the text of the specification. Furthermore, all modifications and changes that fall within the scope of the claims are within the scope of the present invention.

[0031] Evaluation method A test piece was prepared from a 270 MPa grade hot-rolled steel material (SPHC) with mill scale. Also, for 1 L of 10% hydrochloric acid, an aqueous hydrochloric acid solution containing 249.2 g of ferrous chloride tetrahydrate (manufactured by Kanto Chemical Co., Inc.) (70 g as ferrous ions), 4.8 g of ferric chloride hexahydrate (manufactured by Kanto Chemical Co., Inc.) (1 g as ferric ions), and 1.3 g of cupric chloride dihydrate (manufactured by Kanto Chemical Co., Inc.) (500 mg as cupric ions) was prepared as a pickling solution. Then, as described in Example 1 below, a copper deposition inhibitor was added to the pickling solution to obtain a pickling solution for evaluation. After heating this pickling solution for evaluation to 85 °C, the test piece was immersed for 2 minutes, immediately washed with water twice for 10 seconds each, dried, and then the a * value indicating the redness degree of the steel material surface was measured with a color difference meter (Sato Tech Portable Color Difference Meter TES-135A). Furthermore, the copper concentration (wt%) on the surface was measured with a fluorescent X-ray device (Rigaku Portable Component Analyzer NitonXL3t-980S), and the determination of the copper deposition inhibition effect was carried out according to the a * value suppression rate determination criteria and copper deposition inhibition rate determination criteria shown below. When there is a large amount of copper deposition, the a * value (redness) and the surface copper concentration will increase.

[0032] a * Criteria for determining the value suppression rate When no copper deposition inhibitor is used, the a * value is used as the reference a * value, and the evaluation of the a * value suppression rate (%) was carried out as follows. a * Value suppression rate = {1 - (a * value / reference a * value)} × 100 (%) was calculated and evaluated as follows. ◎: Reduction rate of 80% or more with respect to the reference a * value ○: Reduction rate of 70% or more and less than 80% with respect to the reference a * value △: Reduction rate of 60% or more and less than 70% with respect to the reference a * value ×: Reduction rate of 40% or more and less than 60% with respect to the reference a * value XX: Standard a * A reduction rate of less than 40% relative to the value.

[0033] Copper adhesion inhibition rate judgment criteria The copper concentration without the use of a copper adhesion inhibitor was used as the reference copper concentration, and the copper adhesion inhibitory effect was evaluated as follows. Copper deposition inhibition rate = {1 - (copper concentration / reference copper concentration)} × 100 (%) The following evaluation was obtained based on the calculations. ◎: Reduction rate of 80% or more compared to the standard copper concentration ○: Reduction rate of 70% or more but less than 80% relative to the standard copper concentration. △: Reduction rate of 60% or more but less than 70% relative to the standard copper concentration. ×: Reduction rate of 40% or more but less than 60% relative to the standard copper concentration. ××: Reduction rate of less than 40% relative to the standard copper concentration

[0034] The effect of the present invention on copper adhesion inhibitors in acid washing solutions was evaluated using the following Examples 1-5 and Comparative Examples 1-9. The evaluation results are shown in the table.

[0035] [Example 1] As the hydrochloride salt of the polyamine represented by the general formula (1) above, an allylamine hydrochloride polymer with a molecular weight of 5000 (trade name PAA-HCl-05: manufactured by Nitto Boseki Medical Co., Ltd. (hereinafter referred to as "polyamine (a)")) was mixed in 10 parts by weight with 100 parts by weight of water to prepare an aqueous solution of the copper adhesion inhibitor of the present invention. The obtained aqueous solution of the copper adhesion inhibitor was added at a concentration of 1000 ppm to the acid washing solution described in the evaluation method above to prepare an evaluation acid washing solution (copper ion concentration 500 ppm). The effect of the present invention was evaluated using the method shown in the evaluation method above, indicating the degree of redness a * The effect of suppressing the copper content and inhibiting copper adhesion were evaluated. In Example 1, the concentration of the allylamine hydrochloride polymer corresponding to the copper adhesion inhibitor of the present invention in the acid washing solution used for evaluation was 100 ppm.

[0036] [Example 2] The evaluation was carried out in the same manner as in Example 1, except that a diallylamine hydrochloride-sulfur dioxide copolymer with a molecular weight of 5000 (trade name PAS-92: manufactured by Nitto Boseki Medical Co., Ltd. (hereinafter referred to as "polyamine (b)"), which is the hydrochloride salt of the compound represented by the general formula (2) above, was used instead of polyamine (a) in Example 1.

[0037] [Example 3] The evaluation was carried out in the same manner as in Example 1, except that a methyldiallylamine hydrochloride-sulfur dioxide copolymer with a molecular weight of 5000 (trade name PAS-2201CL: manufactured by Nitto Boseki Medical Co., Ltd. (hereinafter referred to as "polyamine (c)"), which is the hydrochloride salt of the compound represented by the general formula (2) above, was used instead of polyamine (a) in Example 1.

[0038] [Example 4] The evaluation was carried out in the same manner as in Example 1, except that a diallyldimethylammonium chloride / sulfur dioxide copolymer with a molecular weight of 5000 represented by the general formula (3) (trade name PAS-A-1: manufactured by Nitto Boseki Medical Co., Ltd. (hereinafter referred to as "polyamine (d)")) was used instead of polyamine (a) in Example 1.

[0039] [Example 5] The evaluation was carried out in the same manner as in Example 1, except that a polycondensate of dicyandiamide with a molecular weight of 2500 represented by the general formula (4) and diethylenetriamine (trade name Neofix E-117: manufactured by Nikka Chemical Co., Ltd. (hereinafter referred to as "polyamine (e)")) was used instead of polyamine (a) in Example 1.

[0040] [Example 6] The evaluation was carried out in the same manner as in Example 1, except that instead of the aqueous solution of the copper adhesion inhibitor in Example 1, an aqueous solution of the copper adhesion inhibitor was prepared by mixing 5 parts by weight of polyamine (a) from Example 1 and 5 parts by weight of polyamine (b) from Example 2 with 100 parts by weight of water.

[0041] [Example 7] The evaluation was carried out in the same manner as in Example 1, except that instead of the aqueous solution of the copper adhesion inhibitor in Example 1, an aqueous solution of the copper adhesion inhibitor was prepared by mixing 5 parts by weight of polyamine (b) from Example 2 and 5 parts by weight of polyamine (e) from Example 5 with 100 parts by weight of water.

[0042] [Example 8] The evaluation was carried out in the same manner as in Example 1, except that instead of the aqueous solution of the copper adhesion inhibitor in Example 1, an aqueous solution of the copper adhesion inhibitor was prepared by mixing 5 parts by weight of polyamine (a) from Example 1 and 5 parts by weight of polyamine (e) from Example 5 with 100 parts by weight of water.

[0043] [Comparative Example 1] To determine the baseline value for evaluating the copper adhesion inhibitory effect, the evaluation was carried out in the same manner as in Example 1 using the evaluation acid cleaning agent that does not contain the copper adhesion inhibitor of the present invention. Then, the measured values ​​of Comparative Example 1 a * The values ​​and copper concentration were used as evaluation criteria.

[0044] [Comparative Example 2] The evaluation was carried out in the same manner as in Example 1, except that polyethyleneimine with a molecular weight of 1800, represented by the following general formula (5) (trade name SP-018: manufactured by Nippon Shokubai), was used instead of polyamine (a) in Example 1. [ka] (In the above general formula, n represents the repeating unit.)

[0045] [Comparative Example 3] The evaluation was carried out in the same manner as in Example 1, except that a diallylamine polymer with a molecular weight of 5000 represented by the following general formula (6) (trade name PAS-21: manufactured by Nitto Boseki Medical) was used instead of polyamine (a) in Example 1. [ka] (In the above general formula, n represents a repeating unit, and R1 is one of hydrogen, a methyl group, or an ethyl group.)

[0046] [Comparative Example 4] The evaluation was carried out in the same manner as in Example 1, except that a methyldiallylamine hydrochloride polymer with a molecular weight of 5000 (trade name PAS-M-1L: manufactured by Nitto Boseki Medical Co., Ltd.), which is the hydrochloride salt of the compound represented by the general formula (6) above, was used instead of polyamine (a) in Example 1.

[0047] [Comparative Example 5] The evaluation was carried out in the same manner as in Example 1, except that a diallyldimethylammonium chloride polymer with a molecular weight of 5000, represented by the following general formula (7) (trade name PAS-H-1L: manufactured by Nitto Boseki Medical), was used instead of polyamine (a) in Example 1. [ka] (In the above general formula, n represents a repeating unit, and R1 and R2 are either a methyl group or an ethyl group, and may be the same group or different groups. X - (This is a counterion.)

[0048] [Comparative Example 6] The evaluation was carried out in the same manner as in Example 1, except that a polycondensate of dicyandiamide with a molecular weight of 20,000 or less and formaldehyde (trade name Unisense KHF11L: manufactured by Senka Co., Ltd.) was used instead of polyamine (a) in Example 1.

[0049] [Comparative Example 7] The evaluation was carried out in the same manner as in Example 1, except that hexamine (molecular weight: 140) represented by the following general formula (8) was used instead of polyamine (a) in Example 1. [ka]

[0050] [Comparative Example 8] The evaluation was carried out in the same manner as in Example 1, except that 2-propyne-1-ol (molecular weight: 56), represented by the following general formula (9), was used instead of polyamine (a) in Example 1. [ka]

[0051] [Comparative Example 9] The evaluation was carried out in the same manner as in Example 1, except that alkylbenzyldimethylammonium chloride represented by the following general formula (10) (molecular weight: 284-424, trade name Sanizol B-50: manufactured by Kao Corporation) was used instead of polyamine (a) in Example 1. [ka] (In the above general formula, R is C8H) 17 ~C 18 H 37 (That is the case.)

[0052] [Comparative Example 10] The evaluation was carried out in the same manner as in Example 1, except that benzyltrimethylammonium chloride represented by the following general formula (11) (molecular weight: 186, trade name BTMAC-50: manufactured by Kao Corporation) was used instead of polyamine (a) in Example 1. [ka]

[0053] Table 1 summarizes the evaluation results of the a* value (redness) suppression effect and copper adhesion inhibition effect for Examples 1-8 and Comparative Examples 1-10. Note that in the evaluation, Comparative Example 1 did not contain a copper adhesion inhibitor in the evaluation acid washing solution, while Examples 1-8 and Comparative Examples 2-10 contained 100 ppm of a copper adhesion inhibitor in the evaluation acid washing solution.

[0054] [Table 1]

[0055] As is clear from the evaluation results of Examples 1-8 and Comparative Examples 1-10, the copper adhesion inhibitor of the present invention exhibits excellent inhibitory effects on copper adhesion to steel materials after cleaning with hydrochloric acid containing copper ions. As a result, it can prevent deterioration of the appearance of steel materials and contribute to improving the quality and yield of steel materials, thus having a very significant industrial effect.

[0056] [Example 9] The evaluation was carried out in the same manner as in Example 1, except that instead of the aqueous solution of the copper adhesion inhibitor in Example 1, 5 parts by weight of polyamine(b) from Example 2 was mixed with 100 parts by weight of water to prepare an aqueous solution of the copper adhesion inhibitor. The concentration of polyamine(b) corresponding to the copper adhesion inhibitor of the present invention in the acid washing solution used for evaluation was 50 ppm.

[0057] [Example 10] The evaluation was carried out in the same manner as in Example 1, except that instead of the aqueous solution of the copper adhesion inhibitor in Example 1, 3 parts by weight of polyamine(b) from Example 2 was mixed with 100 parts by weight of water to prepare an aqueous solution of the copper adhesion inhibitor. The concentration of polyamine(b) corresponding to the copper adhesion inhibitor of the present invention in the acid washing solution used for evaluation was 30 ppm.

[0058] Table 2 summarizes the evaluation results of Examples 2, 9, and 10, in which the amount of polyamine (b), a copper adhesion inhibitor added to the aqueous solution, was varied. In all cases, an excellent inhibitory effect on copper adhesion to steel materials after hydrochloric acid washing containing copper ions was observed.

[0059] [Table 2] [Industrial applicability]

[0060] The copper adhesion inhibitor of the present invention can be used as a copper adhesion inhibiting pickling solution by adding it to the pickling solution of steel produced by steelmaking methods such as electric furnace steelmaking, which use scrap material as a raw material.

Claims

1. A copper adhesion inhibitor for use in acid cleaning solutions for steel materials, characterized by containing one or more compounds or salts thereof from the following general formulas (1) to (4). 【Chemistry 1】 (In the above general formula, n represents the repeating unit.) 【Chemistry 2】 (In the above general formula, n represents a repeating unit, and R1 is one of hydrogen, a methyl group, or an ethyl group.) 【Transformation 3】 (In the above general formula, n represents a repeating unit, and R1 and R2 are either a methyl group or an ethyl group, and may be the same group or different groups. X － (This is a counterion.) 【Chemistry 4】 (In the above general formula, n represents the repeating unit.)

2. A copper adhesion inhibiting acid washing solution characterized by comprising the copper adhesion inhibitor described in claim 1 and an aqueous hydrochloric acid solution.

3. The copper adhesion inhibiting acid washing solution according to claim 2, further characterized by containing copper ions.

4. The copper adhesion inhibiting acid washing solution according to claim 2, characterized in that the concentration of copper ions is 20 ppm or more.

5. A copper adhesion inhibitory acid washing solution according to any one of claims 2 to 4, characterized in that it contains 5 to 3000 mg / L of the copper adhesion inhibitor described in claim 1.

6. A method for pickling steel materials, characterized by pickling the steel materials with the copper adhesion inhibiting acid pickling solution described in claim 2.

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