JP2012036431A - Corrosion inhibitor used for acid cleaning of metal, cleaning liquid composition, and cleaning method of metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion inhibitor for acid cleaning of metal where corrosion inhibiting effect is high when the metal surface is acid-cleaned and variation in corrosion inhibiting rate is small even if the inhibitor concentration varies, and to provide a cleaning method.SOLUTION: This corrosion inhibitor for acid cleaning of metal contains C-Cacylated derivatives (α) of polyalkylene polyamine (A) having a first amino group and/or second amino group, and the content of the acylated derivatives (α) is 0.1-50,000 mg against acid liquid of 1 L. The metal is cleaned by spraying the cleaning liquid composition to the metal surface or dipping the metal surface in the cleaning liquid composition.

Description

  The present invention relates to a corrosion inhibitor used for acid cleaning of metals (hereinafter, also referred to as “corrosion inhibitor for acid cleaning”) and its use, which are excellent in corrosion inhibition effect and stability.

  A black oxide film such as a mill scale adheres to a metal surface such as a metal steel plate. Therefore, when processing rust prevention, plating, etc. on a metal steel sheet for the purpose of improving the performance of the final product, etc., the oxide film is removed before that to prevent rust on the steel sheet surface. It is widely practiced to impart a uniform thickness or to improve the adhesion between the steel sheet surface and the plating film.

  In order to remove scale, rust, etc., pickling using a metal pickling solution (hereinafter also referred to as “acid solution”) is generally performed. Examples of the metal acid cleaning liquid include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, phosphoric acid, sulfamic acid, hydrofluoric acid, oxalic acid, citric acid, glycolic acid, organic acids such as formic acid, chelating agents such as ethylenediaminetetraacetic acid, And aqueous solutions of these and the like. In pickling with a metal pickling solution, scales, rust, etc. are usually very firmly attached to the metal surface, and therefore it takes a considerable amount of time to completely remove them. In addition, when pickling, not only the scale and rust, but also the metal substrate is dissolved and corroded. Therefore, in order to solve such problems, conventionally, a corrosion inhibitor added to an acid has been used. As such a corrosion inhibitor, for example, a nitrogen-containing organic compound is representative.

A quaternary ammonium salt is known as a nitrogen-containing organic compound used as a corrosion inhibitor (see, for example, Patent Document 1). As such a quaternary ammonium salt, 1-vinyl-3-ethylimidazolinium bromide, 3-ethylbenzothiazolium bromide, ethyltriethanolammonium bromide, or the like is used. In addition to these quaternary ammonium salts, it is also known to use a nitrogen-containing organic compound other than the quaternary ammonium salts. For example, hexamethylenetetramine is used (Patent Document 1). Such nitrogen-containing organic compounds have the disadvantage of slowing the pickling rate. Therefore, when these nitrogen-containing organic compounds are contained in the metal acid cleaning solution, the pickling time is further increased, and a reduction in work efficiency is inevitable. It cannot be said that the corrosion inhibiting effect is sufficiently satisfactory.
Moreover, thiourea and its derivative are proposed as a nitrogen-containing organic compound which is a corrosion inhibitor (for example, refer patent document 2). However, thiourea and its derivatives have the same drawbacks as quaternary ammonium salts.

On the other hand, as a nitrogen-containing organic compound that is a corrosion inhibitor, a quaternary ammonium salt-substituted vinyl compound homopolymer, a cationic polymer such as a polyamine compound having a cation unit and a sulfur dioxide unit (for example, see Patent Document 3), etc. It has been known. Of these, polyamine compounds have a higher corrosion-inhibiting effect than conventional nitrogen-containing organic compounds, and are useful as additives for metal acid cleaning solutions. However, recently, the pickling time has been shortened to improve the efficiency of pickling, and as a result, the acid content in the metal pickling solution has been increased. Therefore, development of a corrosion inhibitor having a stronger corrosion inhibition effect is demanded.
In order to effectively suppress corrosion, it is conceivable to use a plurality of metal corrosion inhibitors in combination, but in this case, the concentration ratio of each corrosive changes as it is used, and the corrosion inhibition effect changes. There is a problem that it may easily lead to variations in the final product.
In addition, the presently used copolymer having a cation unit and a sulfur dioxide unit may also change the corrosion inhibitory effect due to a change in the concentration thereof, and the concentration of the corrosion inhibitor in the metal acid cleaning solution using this copolymer. There is a problem that when changes occur over time, it may lead to variations in the final product.

Japanese Patent Laid-Open No. 61-037988 Japanese Patent Laid-Open No. 11-050280 JP 2000-96049 A

  In view of the above background art, the present inventors, when pickling a metal surface, have a strong corrosion inhibitory effect, and even if the inhibitor concentration changes, the corrosion inhibitory effect for metal pickling is small. An attempt was made to develop an agent. As a result, it was surprisingly found that the problem can be achieved by using a specific acylated derivative of polyalkylene polyamine. That is, an object of the present invention is to provide a corrosion inhibitor for pickling metals that has a strong corrosion inhibiting effect when pickling a metal surface and has a small change in corrosion inhibition rate even if the inhibitor concentration changes. is there.

That is, the present invention relates to any one of (1) to (4) below.
(1) A corrosion inhibitor for acid cleaning of a metal comprising a C ₃ -C ₁₅ acylated derivative (α) of a polyalkylene polyamine (a) having a primary amino group and / or a secondary amino group.
(2) The corrosion inhibitor for acid cleaning of a metal according to the above (1), wherein the polyalkylene polyamine (a) is a polyalkyleneimine.
(3) A cleaning liquid composition comprising the acid solution and the corrosion inhibitor according to the above (1) or (2), wherein the content of the acylated derivative (α) is 1 L of the acid solution. The cleaning liquid composition described above, wherein the cleaning liquid composition is 0.1 to 50000 mg.
(4) A method for cleaning a metal, comprising cleaning by spraying the cleaning liquid composition according to the above (3) on a metal surface or immersing the metal surface in the cleaning liquid composition.

  According to the corrosion inhibitor for acid cleaning of a metal of the present invention, corrosion of the metal can be effectively suppressed when the metal surface is acid cleaned. In addition, the metal acid cleaning corrosion inhibitor of the present invention has a very small change in the corrosion inhibition rate even when the inhibitor concentration changes, so that the quality of the final product is easily maintained constant. As a result, the metal acid cleaning corrosion inhibitor of the present invention greatly contributes to the development of various industries such as the metal industry.

Polyalkylene polyamine (a)
In the present invention, examples of the polyalkylene polyamine (a) having a primary amino group and / or a secondary amino group include polyalkylene imines, condensates of alkylene dihalides and alkylene diamines, and polyethylene polyamines.

Examples of the polyalkyleneimine include polyethyleneimine, polypropyleneimine, and an ethylene oxide adduct of polyethyleneimine obtained by adding ethylene oxide leaving at least one amino group capable of amidation.
Polyethyleneimine is available in various products with different molecular weights. When producing polyethyleneimine to be used for acylated polyethyleneimine, ethyleneimine is used as a raw material. However, even when ethyleneimine is polymerized, it does not usually become a completely linear polymer, but the acid concentration, polymerization temperature. A polyethyleneimine having a degree of branching that depends on the production conditions such as and having a tertiary amino group in addition to the primary amino group and the secondary amino group is obtained.

  The preferred molecular weight of polyethyleneimine is from about 600 to about 80,000, most preferably from about 600 to about 25,000.

  Examples of polyethylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

Examples of the alkylene diamine used in the production of the alkylene diamine and alkylene dihalide condensate include ethylene diamine, propylene diamine, butylene diamine, hexamethylene diamine, and piperazine.
On the other hand, examples of the alkylene dihalide used for the production of the condensate include dichloroethane, dibromoethane, and bischloromethylcyclohexane.
There is no restriction | limiting in particular in the manufacturing method of the condensate of alkylenediamine and alkylene dihalide, For example, alkylene dihalide, alkylenediamine, etc. can be made to react at 40-100 degreeC using a solvent as needed. Examples of the solvent used include water, methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, acetone, methyl ethyl ketone, dioxane, tetrahydrofuran, and dimethylformamide. . Since alkylene diamine and alkylene dihalide are easily condensed, polyalkylene polyamine (a) having a primary amino group and / or a secondary amino group can be produced with good productivity and controllability.

  In the present invention, the polyalkylene polyamine (a) is required to have a primary amino group and / or a secondary amino group in the compound.

C ₃ -C ₁₅ acylated derivative (α)
In the present invention, as a corrosion inhibitor, at least a part of the reactive amino group (primary amino group and / or secondary amino group) present in the polyalkylene polyamine (a), that is, a part or all of the reactive amino group. Including C ₃ -C ₁₅ acylated derivatives in which the hydrogen of the amino group is substituted with an acyl group having 3 to 15 carbon atoms, that is, C ₃ -C ₁₅ acylated derivatives (α) of polyalkylene polyamines (a) . When the hydrogen of the amino group is substituted with an acyl group having 3 to 15 carbon atoms, the nitrogen in the amino group and the carbonyl group in the acyl group form an amide bond.
Where the polyalkylene polyamine (a) does not necessarily show a good corrosion inhibition rate as a corrosion inhibitor, a good corrosion inhibition rate can be realized by acylation.

In the case of this C ₃ -C ₁₅ acylated derivative (α), the acyl group R— (CO) — having 3 to 15 carbon atoms preferably comprises at least one selected from the following acyl groups ( R is a hydrocarbon group having 2 to 14 carbon atoms, and may have an unsaturated bond. That is, the acyl group is C _n H _{(2n + 1)} -(CO) — (wherein n is 2 or more and 14 or less, preferably 2 or more and 13 or less, particularly preferably 2 or more and 12 or less. In the formula, C _n H _{(2n + 1)} − may be linear or branched. ); phenyl - (CO) -; substituted phenyl - (CO) -; phenyl _-CH 2 - (CO) -; substituted phenyl _-CH 2 - (CO) -; _{phenyl--C 2 H 4 - (CO)} -; and substituted phenyl _{-C 2 H 4 - (CO)} - is preferably selected from. Here, “substituted phenyl-” refers to a group in which part or all of the hydrogen atoms of the phenyl group are substituted with other groups or atoms, and includes a group consisting of a methyl group, an ethyl group, and a chloro group. It is preferably one substituted with at least one selected group. A polyalkylene polyamine N-acylated with an acetyl group CH ₃ — (CO) — has low hydrophobicity and is easily dissolved in water. On the other hand, the polyalkylene polyamine N-acylated with the acyl group C _n H _{(2n + 1)} -(CO) — (wherein n is 2 or more) becomes more hydrophobic as the number of carbon atoms increases. Similarly, polyamines N-acylated with an acyl group containing an aryl group are highly hydrophobic.

  In order to N-acylate the polyalkylene polyamine (a), a reagent for forming an acylamino group (amide) from an amino group, that is, an acylating agent can be used. Examples of the acylating agent include an acylating agent for forming a corresponding acyl group selected from acyl halide, acyl cyanide, condensed ester of carboxylic acid and alcohol, lactone and carboxylic anhydride.

Further, the C ₃ -C ₁₅ acylated derivative (α) of the polyalkylene polyamine (a) used in the present invention condenses, preferably heat-condenses, the polyalkylene polyamine (a) and the C ₃ -C ₁₅ carboxylic acid. Can also be manufactured.

Cleaning composition The cleaning composition of the present invention is a C ₃ -C ₁₅ acylated derivative (α) of polyalkylene polyamine (a), which is a corrosion inhibitor for acid cleaning of metals of the present invention, with respect to 1 L of acid solution. Is usually 0.1 to 50000 mg, preferably 1 to 10000 mg, and more preferably 1 to 5000 mg in terms of solid or pure form. Since the content is 0.1 mg or more with respect to 1 L of the acid solution, the necessary corrosion inhibiting effect can be obtained, and since it is 50000 mg or less, the corrosion inhibiting effect can be improved according to the added amount.

The acid used for the acid solution is not particularly limited, but inorganic acids such as hydrochloric acid, sulfuric acid, sulfamic acid, and hydrofluoric acid, organic acids such as formic acid, succinic acid, citric acid, malic acid, hydroxyacetic acid, and gluconic acid, ethylenediaminetetraacetic acid, and the like These chelating agents are preferred.
The corrosion inhibitor of the present invention may be added to the acid solution at the time of use, or may be added to the acid solution in advance to obtain the cleaning solution composition of the present invention, which may be used as it is or after being diluted with water. Furthermore, surfactants and solvents may be used to improve the mixing with the cleaning liquid, and the surfactants and solvents used for this purpose may be previously mixed with the corrosion inhibitor of the present invention, separately. You may add to the cleaning composition of this invention.

In addition, the corrosion inhibitor of the present invention may be used in combination with other corrosion inhibitors, and these other corrosion inhibitors may be previously mixed with the corrosion inhibitor of the present invention, and separately washed according to the present invention. It may be added to the agent composition.
Specific examples of other corrosion inhibitors used in combination include 1-vinyl-3-ethylimidazolinium bromide, 3-ethylbenzothiazolium bromide, ethyltriethanolammonium bromide, and the like, but are not limited to these specific examples. Is not to be done.
Furthermore, in the cleaning composition of the present invention, pickling accelerators such as sulfites for improving the pickling rate can be used in combination.

Metal Cleaning Method The metal cleaning method of the present invention is characterized in that the metal surface is cleaned by spraying the cleaning liquid composition of the present invention on the metal surface or immersing the metal surface in the cleaning liquid composition.
The cleaning liquid composition containing the corrosion inhibitor of the present invention is cleaned by spraying the metal surface to be cleaned or immersing the metal piece to be cleaned in the cleaning liquid composition. The metal to be cleaned is not particularly limited, but it is particularly effective when used for steel.

  Hereinafter, the present invention will be described in more detail with reference to examples. The scope of the present invention is not limited by these examples in any way.

Synthesis Example 1 Nonanoyl polyethyleneimine [reaction product of polyethyleneimine and pelargonic acid (1.0: 0.07)]
A 500 ml four-necked separable flask equipped with a stirrer, a condenser and a thermometer was charged with 163.3 g (3.72 mol) of polyethyleneimine (number average molecular weight 2,000), and the internal temperature was raised to 130 ° C. It was. After the temperature was stabilized, 38.8 g (0.24 mol) of pelargonic acid was added, and the acylation reaction was carried out at 130 ° C. for 48 hours. When the solution after completion of the reaction was measured by FTIR, absorption derived from 1400 cm ⁻¹ carboxylic acid (C—O stretching) disappeared and amide absorption was confirmed at 1650 cm ⁻¹ , supporting the target structure. Was. Moreover, since there was no absorption derived from carboxylic acid, such as 1710 cm < ^-1 >, it became clear that acylation advanced quantitatively.

(Synthesis Examples 2 to 4) Nonanoyl polyethyleneimine [reaction product of polyethyleneimine and pelargonic acid (1.0: 0.07)]
Manufacture was carried out by the same operation as in Synthesis Example 1 except that the reaction ratio of polyethyleneimine and pelargonic acid was changed.

(Synthesis example 5) Dodecanoyl polyethyleneimine [Production example of reaction product of polyethylenimine and dodecanoic acid (1.0: 0.07)]
A 500 ml four-necked separable flask equipped with a stirrer, a condenser, and a thermometer was charged with 265.3 g (6.04 mol) of polyethyleneimine (number average molecular weight 2,000), and the internal temperature was raised to 130 ° C. It was. After the temperature was stabilized, 85.8 g (0.42 mol) of dodecanoic acid was added, and an acylation reaction was carried out at 130 ° C. for 48 hours. When the solution after completion of the reaction was measured by FTIR, absorption derived from 1400 cm ⁻¹ carboxylic acid (C—O stretching) disappeared and amide absorption was confirmed at 1650 cm ⁻¹ , supporting the target structure. Was. Moreover, since there was no absorption derived from carboxylic acid, such as 1710 cm < ^-1 >, it became clear that acylation advanced quantitatively.

(Synthesis Examples 6 to 8) Dodecanoyl polyethyleneimine [reaction product of polyethyleneimine and dodecanoic acid]
Manufacture was performed by the same operation as Synthesis Example 1 except that the reaction ratio of polyethyleneimine and dodecanoic acid was changed.

(Synthesis Example 9) Synthesis Example of 1: 1 Copolymer of Diallylamine Hydrochloride and Sulfur Dioxide In a 500 ml four-necked separable flask equipped with a stirrer, a condenser tube, and a thermometer, a 66 mass% diallylamine hydrochloride aqueous solution 202.5 g (1.0 mol) and SO ₂ 64.1 g (1.0 mol) were dissolved in water 206.7 g. Next, 13.7 g of an aqueous ammonium persulfate solution of 28.5% by mass (1.5% by mass with respect to the monomer) was added, and polymerization was carried out at 18 to 60 ° C. for 24 hours. Manufactured. When the solution after completion of the polymerization was measured by the GPC method, the weight average molecular weight was 5,000 and the polymerization rate was 96.0%.
Synthesis Example 10 Synthesis Example of 1: 1 Copolymer of Diallylamine Acetate and Sulfur Dioxide 1 In a 500 ml four-necked separable flask equipped with a stirrer, a condenser, and a thermometer, 1 of diallylamine hydrochloride and sulfur dioxide : 1 copolymer 494.20 g (0.50 mol) and sodium acetate 54.41 g (0.65 mol) were charged and dissolved by stirring to obtain a mixed aqueous solution.
The mixed solution was subjected to ion exchange membrane electrodialysis. Asahi Glass-DU-Ob tank is used as an electrodialyzer, in which cation exchange membrane CMV and anion exchange membrane AMV also made by Asahi Glass are arranged, and the stock solution tank is obtained by the above operation as a stock solution. The mixed aqueous solution was added. Further, a sodium chloride aqueous solution was charged in the concentrated liquid tank. While circulating these liquids, a DC voltage of 16-17 volts was applied between the electrodes to produce the title copolymer used in Comparative Example 2.
When the solution after the treatment was measured by the GPC method, the weight average molecular weight was 5,000 and the yield was 95%.
Synthesis Example 11 Synthesis Example of 1: 1 Copolymer of Methyldiallylamine Hydrochloride and Sulfur Dioxide In a 500 ml four-necked separable flask equipped with a stirrer, a condenser, and a thermometer, 68% by mass methyldiallylamine hydrochloride An aqueous solution 217.1 g (1.0 mol) and SO ₂ 64.1 g (1.0 mol) were dissolved in water 103.7 g. Next, 11.1 g of an aqueous ammonium persulfate solution of 28.5% by mass (1.5% by mass with respect to the monomer) was added, and polymerization was carried out at 18 to 60 ° C. for 24 hours. Manufactured. When the solution after completion of the polymerization was measured by the GPC method, the weight average molecular weight was 4,000 and the polymerization rate was 96.5%.
Synthesis Example 12 Synthesis Example of 1: 1 Copolymer of Diallyldimethylammonium Chloride and Sulfur Dioxide In a 500 ml four-necked separable flask equipped with a stirrer, a condenser, and a thermometer, 65% by mass of DADMAC (diallyl 248.7 g (1.0 mol) of dimethylammonium chloride) and 64.1 g (1.0 mol) of SO ₂ were dissolved in 210.0 g of water. Next, 16.5 g of an aqueous ammonium persulfate solution of 28.5% by mass (1.5% by mass with respect to the monomer) was added, and polymerization was carried out at 18 to 60 ° C. for 72 hours. Manufactured. When the solution after completion of the polymerization was measured by the GPC method, the weight average molecular weight was 4,200, and the polymerization rate was 95.0%.

(Corrosion test)
The corrosion amount was measured by the method described in the following examples.

Example 1
After adding 50 mg or 1000 mg (in terms of solid content) of the corrosion inhibitor obtained in Synthesis Example 1 to 500 ml of a cleaning solution aqueous solution (hereinafter referred to as an acid cleaning solution) containing 50 g of hydrochloric acid, and heating this solution to 80 ° C., A hot-rolled steel sheet (JIS 3131) polished with No. 180 water-resistant abrasive paper was immersed for 10 minutes. The corrosion amount, corrosion inhibition rate, and performance deterioration rate were calculated by the following formulas. The results are shown in Table 1.
Corrosion amount (mg / cm ² ) = [Test piece weight before immersion (mg) −Test piece weight after immersion (mg)] / Test piece surface area (cm ² ) − (1)

(Corrosion inhibition rate)
From the result of the corrosion amount calculated by the above formula (1), the corrosion inhibition rate was calculated according to the following formula (2).
Corrosion inhibition rate (%) = [corrosion amount of Comparative Example 5 (mg / cm ² ) −corrosion amount of each Example or Comparative Example (mg / cm ² )] × 100 / corrosion amount of Comparative Example 5 (mg / cm ² )-(2)
(Performance degradation rate)
From the corrosion inhibition rate when the addition amount of the corrosion inhibitor was 1000 mg and the corrosion inhibition rate when the amount was 50 mg, the performance reduction rate was calculated according to the following formula (3).
Performance degradation rate (%) = 100−A − (3)
(A = (corrosion inhibition rate at 1000 mg addition amount (%) × 100) / corrosion inhibition rate at 50 mg addition amount (%))

(Examples 2 to 8)
The same operation as Example 1 was implemented except having changed the corrosion inhibitor, and the corrosion amount, the corrosion inhibition rate, and the performance fall rate were computed. The results are shown in Table 1.

(Comparative Example 1)
50 mg and 1000 mg (in terms of solid content) of the corrosion inhibitor obtained in Comparative Synthesis Example 1 were added, and the same operation as in Example 1 was performed to calculate the corrosion amount, corrosion inhibition rate, and performance reduction rate. The results are shown in Table 1.

(Comparative Examples 2 to 4)
The same operation as Example 1 was implemented except having changed the corrosion inhibitor, and the corrosion amount, the corrosion inhibition rate, and the performance fall rate were computed. The results are shown in Table 1.

(Comparative Example 5)
Acid cleaning was performed without using a corrosion inhibitor, the same operation as in Example 1 was performed, and the amount of corrosion was calculated. The results are shown in Table 1.

Claims (4)

A corrosion inhibitor for acid cleaning of a metal comprising a C ₃ -C ₁₅ acylated derivative (α) of a polyalkylene polyamine (a) having a primary amino group and / or a secondary amino group.   The corrosion inhibitor for acid cleaning of metals according to claim 1, wherein the polyalkylene polyamine (a) is a polyalkyleneimine.   A cleaning liquid composition comprising the acid solution and the corrosion inhibitor according to claim 1 or 2, wherein the content of the acylated derivative (α) is 0.1 to 50,000 mg with respect to 1 L of the acid solution. The cleaning liquid composition as described above.   A metal cleaning method, comprising: cleaning the metal surface by spraying the cleaning liquid composition according to claim 3 or immersing the metal surface in the cleaning liquid composition.