JP2016183370A - Dissolving and removing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dissolving and removing composition that has excellent dissolution rates of rust and scale and can also inhibit the corrosion of a metal matrix.SOLUTION: A dissolving and removing composition has (A) a base compound comprising phosphonic acid chelator of 0.1 mass% or more and 30 mass% or less and (B) a dissolution promoter comprising iron oxide having divalent iron of 0.010 mass% or more.SELECTED DRAWING: None

Description

  The present invention relates to a dissolution / removal composition such as rust and scale containing a metal oxide, and more particularly to a dissolution / removal composition excellent in the dissolution rate of rust and scale.

Conventionally, there has been proposed a dissolution method for a scale that uses a dissolution remover mainly composed of phosphonic acid or the like in a neutral region to remove a scale containing a metal oxide attached to a metal surface (for example, a patent document). 1). In this scale dissolution method, iron powder etc. are mixed in the cleaning solution, and iron powder dissolves, and Fe ²⁺ is generated, so that a reducing atmosphere is formed. Is possible.

Japanese Patent No. 3202414

  However, in the method for dissolving and removing the scale described in Patent Document 1, iron powder dispersed in the cleaning liquid may precipitate, the dissolution rate of the scale is slow, and the dissolution time of the scale may be delayed. Further, in the method for dissolving and removing the scale described in Patent Document 1, depending on the type of the corrosion inhibitor used in combination with the dissolving and removing agent, the dissolution reaction of metallic iron may be suppressed and a sufficient dissolution rate of the scale may not be obtained. is there.

  This invention is made | formed in view of such a situation, and it aims at providing the melt | dissolution removal composition which is excellent in the melt | dissolution rate of rust and a scale, and can suppress the corrosion of a metal base material.

  The dissolution removal composition of the present invention comprises (A) a main component containing a phosphonic acid chelating agent in an amount of 0.1% by mass to 30% by mass, and (B) a dissolution promotion containing an iron oxide having divalent iron. And 0.010% by mass or more of the agent.

  According to the dissolution and removal composition of the present invention, a reducing atmosphere is formed at the interface between the scale and the dissolution and removal composition by iron oxide having a lower oxidation-reduction potential than rust and scale components. For example, a scale component containing metal oxides such as magnetite and hematite is promoted while the dissolution reaction of rust and scale components is accelerated while preventing an increase in corrosion weight loss of the metal base material even under pH 4-8) conditions. Can be quickly removed. Therefore, it is possible to realize a dissolution and removal composition that is excellent in the dissolution rate of the scale and can suppress the corrosion of the metal base material.

In the dissolution removing composition of the present invention, (B) the dissolution accelerator is at least one selected from the group consisting of FeO, Fe ₃ O ₄ and Fe (OH) _{2 in} which the iron oxide having divalent iron is used. It is preferable to contain.

  In the dissolution removal composition of the present invention, the phosphonic acid chelating agent contains 1-hydroxyethane-1,1-diphosphonic acid, aminotris (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), hexamethylenediaminetetrakis ( Methylenephosphonic acid), diethylenetetraminepentakis (methylenephosphonic acid), and phosphonic acids consisting of 2-phosphonobutane-1,2,4-tricarboxylic acid, and at least one selected from the group consisting of salts of the phosphonic acids It is preferable to contain.

  The dissolution removal composition of the present invention preferably further comprises (C) a reducing agent.

  In the dissolution removal composition of the present invention, (C) the reducing agent is at least one selected from the group consisting of ersorbic acid, gallic acid, pyrogallol, hydrazine, ascorbic acid, a sulfur reducing agent, and thioureas. Preferably there is.

  In the dissolution and removal composition of the present invention, the sulfur-based reducing agent is selected from the group consisting of sulfites, hydrogen sulfites, pyrosulfites, thiosulfates, dithionites, thionates, polythionates, and thiourea dioxide. It is preferable to include at least one selected from the above.

  In the dissolution and removal composition of the present invention, it is preferable that the thioureas include at least one selected from the group consisting of alkylthiourea and guanylthiourea.

  The dissolution removal composition of the present invention preferably further contains (D) a corrosion inhibitor.

  ADVANTAGE OF THE INVENTION According to this invention, the melt | dissolution removal composition which is excellent in the melt | dissolution rate of a rust and a scale, and can suppress corrosion of a metal base material is realizable.

FIG. 1A is a conceptual diagram of operational effects of the dissolution and removal composition according to the embodiment of the present invention. FIG. 1B is a conceptual diagram of the function and effect of the dissolution and removal composition according to the embodiment of the present invention. FIG. 1C is a conceptual diagram of the effects of the dissolution and removal composition according to the embodiment of the present invention. FIG. 2 is a graph showing the relationship between the dissolved iron concentration and time of the dissolution composition according to the example of the present invention. FIG. 3 is a diagram illustrating a relationship between ORP and time according to the embodiment of the present invention. FIG. 4 is a diagram showing the relationship between dissolved iron concentration and time by the dissolution and removal composition according to the example of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited to each following embodiment, It can implement by changing suitably.

  The dissolution removal composition according to the present invention comprises (A) a main component containing a phosphonic acid chelating agent in an amount of 0.1% by mass to 30% by mass, and (B) a dissolution containing an iron oxide having divalent iron. And 0.010% by mass or more of an accelerator.

  According to the dissolution / removal composition of the present invention, the scale component and the dissolution / removal composition are formed by an oxide having a lower acid reduction potential than the scale component included in the scale attached to a heat exchanger or the like for land boilers and various plants. Since the scale component is reduced and dissolved by forming a reducing atmosphere at the interface, the dissolution rate of the scale component even under conditions of normal temperature and neutral range (for example, pH 4 to 8) without using heating equipment Can be improved. Moreover, since iron oxide having a lower acid reduction potential than hematite contained in the scale component is used, a reducing atmosphere is formed at the interface between the scale containing hematite and the dissolution removal composition, and corrosion of the metal base material is prevented. While suppressing, the scale containing hematite can also be quickly dissolved and removed.

FIG. 1A to FIG. 1C are conceptual diagrams of operational effects of the dissolution and removal composition according to the present invention. In general, the scale 12 attached to the surface of the metal pipe 11 has, for example, Fe ₃ O ₄ which is a divalent and trivalent iron oxide as a main component. Since the dissolution removal composition 13 according to the present invention contains iron oxide having a lower oxidation-reduction potential than the scale component contained in the scale 12, the dissolution reduction composition 13 has an oxidation-reduction potential (ORP) of −0 quickly. It is in the range of .8V or more and -0.2V or less (vs. SSE). As a result, electrons (e ⁻ ) are donated from the iron oxide contained in the dissolution composition 13 to the scale 12, and the surface 12 a of the scale 12 is Fe ₃ O ₄ that is trivalent iron oxide and trivalent iron. It is estimated that oxides such as Fe ₂ O ₃ are reduced. Since the divalent iron ions formed by this reduction are presumed to have a relatively large amount of dissolution in the phosphonic acid chelating agent that is the main agent, the removal rate of rust and scale 12 can be improved. Since the scale 12 can be quickly removed by the reduction of the scale 12, it is estimated that the corrosion weight loss on the metal base material such as the metal pipe 11 can also be reduced. Hereinafter, various components of the dissolution removal composition according to the present embodiment will be described in detail.

(A) Main agent (A) As the main agent, a chelating agent containing a phosphorus atom such as a phosphonic acid chelating agent and a salt thereof are used. The phosphonic acid chelating agent is not particularly limited as long as it can remove a scale containing a metal oxide such as rust, and various phosphonic acid chelating agents can be used. Moreover, as (A) main ingredient, you may add and use amines, such as hydroxides of various alkali metals, such as sodium hydroxide and potassium hydroxide, diethanolamine, and triethanolamine.

  Examples of the phosphonic acid chelating agent include 1-hydroxyethane-1,1-diphosphonic acid, aminotris (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), hexamethylenediaminetetrakis (methylenephosphonic acid), and diethylenetetramine. Examples thereof include various phosphonic acids such as pentakis (methylenephosphonic acid) and 2-phosphonobutane-1,2,4-tricarboxylic acid, and salts of various phosphonic acids. These chelating agents may be used individually by 1 type, and may use 2 or more types together. Among these, phosphonic acid-based chelating agents include 1-hydroxyethane-1,1-diphosphonic acid, aminotris (methylenephosphonic acid) from the viewpoint of excellent dissolution rate of rust and scale and from the viewpoint of inhibiting corrosion of the metal base material. ), Ethylenediaminetetrakis (methylenephosphonic acid), and hexamethylenediaminetetrakis (methylenephosphonic acid) are preferred.

  In addition, as a phosphonic acid type | system | group chelating agent, another chelating agent and organic acid can also be added and used in the range with the effect of this invention. Examples of other chelating agents include various aminocarboxylic acids such as nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and triethylenetetraminehexaacetic acid, and salts of various aminocarboxylic acids.

  Examples of the organic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, dicarboxylic acid such as decane-1,10-dicarboxylic acid, and dicarboxylic acid salt, Diglycolic acid, thiodiglycolic acid, oxaloacetic acid, oxydisuccinic acid, carboxymethyloxysuccinic acid, carboxymethyltartronic acid and their salts, malic acid, tartaric acid, citric acid, itaconic acid, methylsuccinic acid, 3-methylglutar Acid, 2,2-dimethylmalonic acid, maleic acid, fumaric acid, 1,2,3-propanetricarboxylic acid, aconitic acid, 3-butene-1,2,3-tricarboxylic acid, butane-1,2,3 4-tetracarboxylic acid, ethanetetracarboxylic acid, ethenetetracarboxylic acid, n-alkenylaconitic acid 1,2,3,4-cyclopentanetetracarboxylic acid, phthalic acid, trimesic acid, hemimellitic acid, pyromellitic acid, benzenehexacarboxylic acid, tetrahydrofuran-1,2,3,4-tetracarboxylic acid, tetrahydrofuran-2 2,5,5-tetracarboxylic acid, and salts thereof. These organic acids may be used alone or in combination of two or more.

  In the dissolution and removal composition according to the present invention, from the viewpoint of efficiently removing rust and scale, (A) main ingredients include aminotris (methylenephosphonic acid), 1-hydroxyethane-1,1-diphosphonic acid, and ethylenediamine. Various phosphonic acids such as tetrakis (methylenephosphonic acid), hexamethylenediaminetetrakis (methylenephosphonic acid), diethylenetetraminepentakis (methylenephosphonic acid), and 2-phosphonobutane-1,2,4-tricarboxylic acid, and various phosphones It preferably contains at least one selected from the group consisting of salts of acids, and more preferably contains 1-hydroxyethane-1,1-diphosphonic acid.

(B) Dissolution accelerator (B) As the dissolution accelerator, an iron oxide having divalent iron (Fe) is used. The iron oxide having divalent iron is not particularly limited as long as it can remove scales containing metal oxides such as rust and iron, and various iron oxides can be used. Examples of the iron oxide having divalent iron include oxides such as FeO and Fe ₃ O ₄ and hydroxides such as Fe (OH) ₂ . These iron oxides may be used individually by 1 type, and may use 2 or more types together.

The iron oxide having divalent iron is composed of FeO, Fe ₃ O ₄ and Fe (OH) ₂ from the viewpoint of promoting the reduction of scale components including metal oxides such as rust and iron to improve the solubility. It is preferable to include at least one selected from the group, and it is more preferable to include FeO. As the iron oxide having divalent iron, it is preferable to use an iron oxide having a lower redox potential than the scale component to be dissolved and removed. For example, when the scale component includes Fe ₂ O ₃ , the iron oxide having divalent iron may include at least one of FeO and Fe ₃ O ₄ having a lower redox potential than Fe ₂ O _3. preferable. Also, if the scale component includes _Fe 3 _{O 4} is iron oxide having a divalent iron preferably contains FeO is lower redox potential than _Fe 3 _{O 4.}

(C) Reducing agent The dissolution removal composition of the present invention preferably further comprises (C) a reducing agent. When the dissolution and removal composition contains (C) a reducing agent, corrosion of the base material to which scales such as metal pipes adhere can be prevented due to the reducing property of the reducing agent. In addition, since the dissolution removal composition contains (C) a reducing agent, the reduction of the scale component by iron oxide is promoted in the range where the redox potential is −0.2 V or less (vs. SSE), and the dissolution of the scale component is achieved. It is possible to obtain a synergistic effect that accelerates the start time and dissolution rate.

As the reducing agent, various compounds can be used as long as the effects of the present invention are exhibited. Examples of the reducing agent include sorbic acid, gallic acid, ascorbic acid, sulfur-based reducing agent, thioureas, pyrogallol, hydrazine, carbohydrazide, oxidizable metals such as Fe, Sn, Al, and Zn, Fe ²⁺ , and Sn. ^Examples include oxidizable metal ions such as ²⁺ , oxalic acid, formic acid and hydrogen peroxide. Among these, ersorbic acid, gallic acid, pyrogallol, hydrazine, ascorbic acid, sulfur-based reducing agent and thiol are used from the viewpoints of improving the dissolution rate of the scale due to the above-described effects, and suppressing the corrosion of the metal base material. At least one selected from the group consisting of ureas is preferable, and ersorbic acid and ascorbic acid are more preferable.

  As the sulfur-based reducing agent, various sulfur-containing compounds can be used as long as the effects of the present invention are achieved. Sodium sulfite, potassium sulfite, calcium sulfite, zinc sulfite, ammonium sulfite and other sulfites, sodium hydrogen sulfite, potassium bisulfite, ammonium bisulfite and other bisulfites, sodium pyrosulfite, potassium pyrosulfite, pyro pyrosulfite and other pyrosulfites Thiosulfates such as sulfites, sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, dithionite and dithionite, thionate and thionate, trithionate, tetrathionate and other polythionate and polythionate And thiourea dioxide. These sulfur type reducing agents may be used individually by 1 type, and may use 2 or more types together.

  As the sulfur-based reducing agent, various compounds can be used as long as the effects of the present invention are achieved. Among these, from the viewpoint of improving the dissolution rate of the scale due to the above-described effects, and from the viewpoint of suppressing corrosion of the metal base material, sulfites, hydrogen sulfites, pyrosulfites, thiosulfates, dithionites, At least one selected from the group consisting of thioic acids, polythioic acids, and thiourea dioxide is preferred.

  Examples of thioureas include thiourea, methylthiourea, ethylthiourea, N, N′-dimethylthiourea, N, N′-diethylthiourea, N, N′-di-n-propylthiourea, dicyclohexylthiourea, trimethylthiourea. Alkylthiourea such as triethylthiourea, tri-n-propylthiourea, tricyclohexylthiourea, tetramethylthiourea, tetraethylthiourea, tetra-n-propylthiourea, tetracyclohexylthiourea, and guanylthiourea. As these thioureas, 1 type may be used independently and 2 or more types may be used together.

  As the thioureas, alkylthiourea and guanylthiourea are more preferable from the viewpoint of removing scales containing metal oxides and suppressing corrosion of the metal base material.

(D) Corrosion inhibitor The dissolution removal composition of the present invention preferably further comprises (D) a corrosion inhibitor. When the dissolution and removal composition contains (D) a corrosion inhibitor, it is possible to prevent corrosion of a base material to which a scale such as a metal pipe is attached. (D) As the corrosion inhibitor, for example, amphoteric surfactants and nonionic surfactants can be used.

  As the amphoteric surfactant, various double-sided surfactants can be used as long as the effects of the present invention are exhibited. Examples of the amphoteric surfactant include 2-alkyl-N-carboxyalkyl-N-hydroxyalkylimidazolinium betaine represented by the following formula (1) and β-alkyl represented by the following general formula (2). It preferably contains at least one selected from the group consisting of alkali metal salts of aminocarboxylic acids and alkyldimethylbetaines represented by the following general formula (3).

（上記式（１）、上記式（２）及び上記式（３）中、Ｒ_１、Ｒ_４、及びＲ_７は、水素原子又は炭素数が１〜２０の分岐があってもよいアルキル基、アルケニル基、アルキニル基、炭素数が６〜２０のアリール基、ベンジル基、複素環基を表し、Ｒ_２及びＲ_５は、炭素数が１〜３のアルキレン基を表し、Ｒ_３は、炭素数が１〜２０の分岐があってもよいアルキル基、アルケニル基、アルキニル基、炭素数が６〜２０のアリール基、ベンジル基、複素環基を表し、Ｒ_６は、水素原子又は炭素数が１〜２０の分岐があってもよいアルキル基、アルケニル基、アルキニル基、炭素数が６〜２０のアリール基、ベンジル基、複素環基を表し、Ｍは、ナトリウム、カリウム、リチウムなどのアルカリ金属を示す。）

(The above formula (1), the formula (2) and the formula _(3), R 1, _{R 4,} and _{R 7} is an alkyl group if there is a branch of the hydrogen atom or having 1 to 20 carbon atoms, An alkenyl group, an alkynyl group, an aryl group having 6 to 20 carbon atoms, a benzyl group, or a heterocyclic group; R ₂ and R ₅ represent an alkylene group having 1 to 3 carbon atoms; and R ₃ represents a carbon number. Represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group having 6 to 20 carbon atoms, a benzyl group, or a heterocyclic group, which may have 1 to 20 branches, and R ₆ represents a hydrogen atom or a carbon number of 1 Represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group having 6 to 20 carbon atoms, a benzyl group, or a heterocyclic group, which may have a branch of -20, and M represents an alkali metal such as sodium, potassium, or lithium. Show.)

  Examples of the amphoteric surfactants represented by the general formula (1) and the general formula (2) include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and 2-alkyl-N-. Carboxyethyl-N-hydroxyethyl imidazolinium betaine is mentioned. Examples of amphoteric surfactants include 2-cocoalkyl-1-carboxymethyl-1-hydroxyethyl-4,5-dihydroimidazolinium hydroxide and sodium β-coconut alkylaminopropionate from the viewpoint of inhibiting corrosion of the metal matrix. Is preferred. One amphoteric surfactant may be used alone, or two or more amphoteric surfactants may be used in combination.

  As the amphoteric surfactant, at least one compound represented by the general formula (1) and the general formula (2) is preferable. According to this configuration, since the amphoteric surfactant has a carboxylic acid group and a nitrogen atom, the amphoteric surfactant is adsorbed on the surface of the metal base material by these substituents, while it is adsorbed on the surface of rust and scale. Therefore, it is considered that the corrosion resistance of the metal base material can be further enhanced while preventing the deterioration of rust and scale dissolution removal performance.

  Examples of nonionic surfactants include fatty acid esters and polyoxyalkylene alkyl ethers. Examples of fatty acid esters include fatty acid esters of polyoxyalkylene alcohol represented by the following general formula (4). Moreover, as a polyoxyalkylene alkyl ether, the polyoxyalkylene alkyl ether represented by following General formula (5) is mentioned.

（上記式（４）及び上記式（５）中、Ｒ_８は、分岐を有していてもよい炭素数が８〜２４のアルキル基又はアルケニル基を表し、Ｒ_９は、分岐を有していてもよい炭素数が８〜２４のアルキル基又はアルケニル基を表す。ｎは、２〜３であり、ｍは整数である。）

In (the formula (4) and the formula (5), R ₈ is the number of carbon atoms which may have a branch represents an alkyl or alkenyl group of 8 to 24, R ₉ is not a branch And represents an alkyl group or alkenyl group having 8 to 24 carbon atoms, n is 2 to 3, and m is an integer.)

  Examples of the fatty acid ester of the polyoxyalkylene alcohol represented by the general formula (4) include polyethylene glycol monooleate, polyethylene glycol monolaurate, and polyethylene glycol monostearate.

  The polyoxyalkylene alkyl ether represented by the general formula (5) includes higher alcohols such as oleyl alcohol, lauryl alcohol and stearyl alcohol, EO (ethylene oxide), PO (propylene oxide), or EO (ethylene oxide). And PO (propylene oxide) added. Examples of the polyoxyalkylene alkyl ether represented by the general formula (5) include polyoxyalkylene oleyl ether, polyoxyalkylene lauryl ether, and polyoxyalkylene stearyl ether.

  As the nonionic surfactant, fatty acid esters are preferred. With this configuration, since the nonionic surfactant has a fatty acid ester structure and an alkyl ether structure, it is considered that a stable coating is formed on the metal base material and high anticorrosion properties are obtained.

  The nonionic surfactant is more preferably at least one selected from the group consisting of polyoxyalkylene glycol fatty acid esters, polyalkylene glycol fatty acid esters, and polyoxyalkylene alkyl ethers. With this configuration, since the nonionic surfactant has a fatty acid ester structure and an alkyl ether structure, it is considered that a stable coating is formed on the metal base material and high anticorrosion properties are obtained. Further, as the nonionic surfactant, polyethylene alkylene glycol oleate and polyoxyalkylene oleyl ether are more preferable from the viewpoint of inhibiting corrosion of the metal base material.

  As the corrosion inhibitor, a commercially available betaine surfactant (trade name: Ademin # 2304, manufactured by Kyoeisha Chemical Co., Ltd.) or the like may be used.

(E) Other components The dissolution / removal composition according to the present invention can contain other components other than the above-described compounds within the scope of the effects of the present invention. Other components include, for example, water such as pure water or distilled water that dissolves (A) the main agent and (B) dissolution accelerator, various solvents, and pH such as potassium hydroxide that adjusts the acidity of the dissolution and removal composition. Examples of the adjusting agent include a dissolved oxygen removing agent for removing oxygen present in the cleaning liquid, pyrogallol and sodium sulfite.

  In the dissolution and removal composition according to the present invention, (A) the amount of the main component is dissolved and removed from the viewpoint of improving the dissolution rate of the scale containing the metal oxide and from the viewpoint of inhibiting the corrosion of the metal matrix. 0.1% by mass or more is preferable, 0.5% by mass or more is more preferable, 1% by mass or more is more preferable, 30% by mass or less is preferable, and 20% by mass or less is more preferable with respect to the total mass of the product. 5 mass% or less is still more preferable. Considering the above, the blending amount of the main component (A) is preferably 0.1% by mass or more and 30% by mass or less, and 0.5% by mass or more and 20% by mass or less with respect to the total mass of the dissolution composition. More preferably, the content is 1% by mass or more and 5% by mass or less.

  In the dissolution and removal composition according to the present invention, the blending amount of the (B) dissolution accelerator is the total mass of the dissolution and removal composition from the viewpoint of removing scales containing metal oxides and inhibiting corrosion of the metal base material. On the other hand, 0.010% by mass or more is preferable, 0.020% by mass or more is more preferable, 0.030% by mass or more is further preferable, 1% by mass or less is preferable, and 0.75% by mass or less is more preferable. 0.5 mass% or less is still more preferable. Considering the above, the blending amount of the (B) dissolution promoter is preferably 0.010% by mass or more and 1% by mass or less, and 0.020% by mass or more and 0.75% with respect to the total mass of the dissolution removal composition. The mass% is more preferable, and 0.030 mass% or more and 0.5 mass% or less is still more preferable.

  In the dissolution and removal composition according to the present invention, the blending amount of the (B) dissolution accelerator is (A) 100 parts by mass of the main agent from the viewpoint of removing scales containing metal oxides and inhibiting corrosion of the metal base material. On the other hand, 0.01 parts by mass or more is preferable, 0.25 parts by mass or more is more preferable, 0.5 parts by mass or more is more preferable, 15 parts by mass or less is preferable, and 12.5 parts by mass or less is more preferable. 10 parts by mass or less is more preferable. Considering the above, the blending amount of the (B) dissolution accelerator is preferably 0.01 parts by mass or more and 15 parts by mass or less, and 0.25 parts by mass or more and 12.5 parts by mass with respect to 100 parts by mass of the main component (A). The amount is more preferably equal to or less than mass parts, and still more preferably equal to or greater than 0.5 parts by mass and equal to or less than 10 parts by mass.

  In the dissolution / removal composition according to the present invention, the amount of (C) the reducing agent added is based on the total mass of the dissolution / removal composition from the viewpoint of removing scales containing metal oxides and inhibiting corrosion of the metal matrix. 0.001% by mass or more is preferable, 0.01% by mass or more is more preferable, 0.1% by mass or more is more preferable, 5.0% by mass or less is preferable, and 2.5% by mass or less is more preferable. 1 mass% or less is still more preferable. Considering the above, the blending amount of (C) the reducing agent is preferably 0.001% by mass or more and 5.0% by mass or less, and 0.01% by mass or more and 2.% by mass or less with respect to the total mass of the dissolution composition. 5 mass% or less is more preferable, and 0.1 mass% or more and 1 mass% or less are still more preferable.

  In the dissolution and removal composition according to the present invention, the amount of (C) the reducing agent blended is (A) based on 100 parts by mass of the main agent from the viewpoint of removing scales containing metal oxides and inhibiting corrosion of the metal base material. 0.1 parts by mass or more, preferably 0.25 parts by mass or more, more preferably 0.5 parts by mass or more, more preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and 60 parts by mass. The following is more preferable. Considering the above, the blending amount of (C) the reducing agent is preferably 0.1 parts by mass or more and 80 parts by mass or less, and 0.25 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the main component (A). Is more preferably 0.5 parts by mass or more and 60 parts by mass or less.

  In the dissolution / removal composition according to the present invention, the blending amount of the (D) corrosion inhibitor is 0.001% by mass or more based on the total mass of the dissolution / removal composition from the viewpoint of inhibiting the corrosion of the metal base material. Preferably, 0.01% by mass or more is more preferable, 0.1% by mass or more is more preferable, 5.0% by mass or less is preferable, 2.5% by mass or less is more preferable, and 1% by mass or less is more preferable. . Considering the above, the blending amount of the (D) corrosion inhibitor is preferably 0.001% by mass or more and 5.0% by mass or less, and 0.01% by mass or more and 2% by mass with respect to the total mass of the dissolution removal composition. 0.5 mass% or less is more preferable, and 0.1 mass% or more and 1 mass% or less are still more preferable.

(Method for producing dissolved removal composition)
Next, the manufacturing method of the dissolution removal composition concerning this invention is demonstrated. There is no restriction | limiting in particular in the manufacturing method of the melt | dissolution removal composition which concerns on this invention. Examples of the method for producing the dissolution removal composition include (A) a main agent and (B) a dissolution accelerator in water such as pure water or distilled water, (C) a reducing agent, and (D) a corrosion inhibitor, if necessary. And (E) Each component such as other components is sequentially added and mixed at room temperature, and a base such as potassium hydroxide is added to adjust the pH to a predetermined range (for example, 4 to 8). be able to. Here, when using a sulfur reducing agent, the deterioration of the sulfur reducing agent is prevented by mixing the main agent and the sulfur reducing agent immediately before use and degassing the sulfur reducing agent with an inert gas. It becomes possible. Further, from the viewpoint of preventing the deterioration of the sulfur-based reducing agent, a reducing agent for the oxygen concentration in the cleaning liquid may be used. Moreover, the dissolution removal composition according to the present invention can also be produced by sequentially adding and mixing each component into a pipe through which boiler cooling water or the like passes. In addition, the dissolution removal composition concerning this invention can be used in nitrogen atmosphere, and can also be manufactured under air atmosphere.

  As described above, according to the dissolution and removal composition according to the present invention, a reducing atmosphere is formed at the interface between the scale and the dissolution and removal composition by the iron oxide having a lower acid reduction potential than the scale component. In addition, the scale component containing magnetite and hematite is suppressed under the condition of neutral region (for example, pH 4 to 8) while the dissolution start and dissolution rate of the scale component are promoted and the corrosion of the metal base material is suppressed. It can be quickly dissolved and removed. This makes it possible to clean at room temperature, shortening the cleaning process of scale components adhering to heat exchangers, etc., and reducing the scale cleaning temporary equipment and temporary piping connection work for dissolving scale components. The cost of cleaning the components can be reduced. In addition, since the scale component can be dissolved and removed without using metallic iron, a stable scale dissolution rate can be obtained regardless of the type of reducing agent. In addition, inert treatment during storage after preparation of the dissolution composition is not necessary, and it is possible to prevent odors based on sulfur components and corrosion of the base material of the heat exchanger and generation of precipitates on the base material. It becomes.

  Moreover, according to the dissolution and removal composition according to the present invention, the dissolution and removal composition having excellent dissolution and removal performance such as scale can be adjusted simply by mixing (A) the main agent and (B) the dissolution accelerator. The handling of the composition is facilitated. Furthermore, in the conventional scale-dissolving composition, the amount of corrosion of the metal base material can be remarkably reduced even when it is used for piping using an amphoteric metal having a large amount of corrosion as a metal base material. Furthermore, according to the dissolution and removal composition according to the present invention, the corrosion of the metal base material can be reduced, so that generation of hydrogen gas and the like can be prevented. Moreover, according to the dissolution removal composition according to the present invention, scale can be removed without coexisting powders such as metallic iron. By these, the dissolution removal composition according to the present invention is a land boiler, various plants, ships, power generation facilities, engines, transportation facilities, heat exchangers, iron parts, oxide scales, various products to which rust adheres, and It can be suitably used for cleaning various parts.

  Hereinafter, the present invention will be described in more detail based on examples made to clarify the effects of the present invention. In addition, this invention is not restrict | limited at all by the following Examples and Comparative Examples.

Example 1
After putting a stir bar in the separable flask, the main agent and distilled water are added so that the concentration of (A) main agent (1-hydroxyethane-1,1-diphosphonic acid, manufactured by Wako Pure Chemical Industries, Ltd.) is 3% by mass. After the addition, the inside of the separable flask was set to a nitrogen atmosphere. Next, while maintaining the separable flask at 25 ° C. and stirring, the concentration of (B) dissolution accelerator A (FeO, manufactured by Kishida Chemical Co., Ltd.) was 0.1% by mass, and (D) a corrosion inhibitor (betaine system) Various agents were sequentially added and mixed so that the concentration of the surfactant (trade name: Ademin # 2304, manufactured by Kyoeisha Chemical Co., Ltd.) was 0.1% by mass. Thereafter, in a state where the separable flask was kept at 25 ° C. in a constant temperature water bath, an aqueous solution of sodium hydroxide was dropped to adjust the pH to 6.5 to prepare a dissolution removal composition. The amount of each component is shown in Table 1 below.

<Solubility test>
To 200 ml of the prepared dissolution composition, 1.5 g of magnetite powder was added as an evaluation scale, and the dissolved iron concentration was analyzed for 50 hours by the sulfosalicylic acid method every predetermined time. Thereafter, the residue was suction filtered through a glass filter and dried in a desiccator, and the weight of the residue was measured to determine the dissolved iron concentration. The dissolution start time was the time when the dissolved iron concentration exceeded the detection lower limit, and the dissolution completion time was the time when the dissolved iron concentration exceeded 3000 mg / L. Further, 3000 mg (dissolution completion time-dissolution start time) was defined as the dissolution rate (mg as Fe / L / H). Moreover, the change of ORP at the time of a solubility test was measured. In addition, a test piece (SS-400, surface area of 30 cm ² ) was added to the prepared dissolution composition, and the corrosion weight loss (mdd: mg / dm ² / day) was measured.

(Example 2)
A dissolution removal composition was prepared and a solubility test was performed in the same manner as in Example 1 except that reducing agent A (ascorbic acid, manufactured by Kishida Chemical Co., Ltd.) was added so that the concentration was 0.2% by mass. . The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

Example 3
A dissolution / removal composition was prepared in the same manner as in Example 1 except that reducing agent B (Elsorbic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was added so as to have a concentration of 0.2% by mass. Carried out. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

Example 4
Dissolution removal in the same manner as in Example 2, except that dissolution accelerator B (Fe (OH) ₂ , manufactured by Chemos GmbH) was added instead of dissolution accelerator A so that the concentration became 0.1% by mass. A composition was prepared and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 5)
Dissolving and removing composition in the same manner as in Example 2 except that main agent B (aminotris (methylenephosphonic acid), manufactured by Tokyo Chemical Industry Co., Ltd.) was added in place of main agent A so as to have a concentration of 5.0% by mass. A product was prepared and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 6)
Dissolution removal in the same manner as in Example 5 except that a dissolution accelerator B (Fe (OH) ₂ , manufactured by Chemos GmbH) was added in place of the dissolution accelerator A so as to have a concentration of 0.1% by mass. A composition was prepared and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 7)
Dissolving and removing in the same manner as in Example 5 except that the main agent C (ethylenediaminetetrakis (methylenephosphonic acid), manufactured by Wako Pure Chemical Industries, Ltd.) was added instead of the main agent B so that the concentration became 5.0% by mass. A composition was prepared and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 8)
Dissolution removal in the same manner as in Example 7 except that dissolution accelerator B (Fe (OH) ₂ , manufactured by Chemos GmbH) was added instead of dissolution accelerator A so that the concentration was 0.1% by mass. A composition was prepared and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

Example 9
Instead of the dissolution accelerator A, the dissolution accelerator C (Fe ₃ O ₄ , manufactured by Wako Pure Chemical Industries, Ltd.) was added so that the concentration became 0.1% by mass, and the evaluation scale was replaced with magnetite, and hematite was replaced. A dissolution removal composition was prepared in the same manner as in Example 2 except that it was used, and a solubility test was performed. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 10)
A dissolution removal composition was prepared and a solubility test was conducted in the same manner as in Example 1 except that the main agent A was added so as to have a concentration of 0.8% by mass. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 11)
A dissolution removal composition was prepared and a solubility test was conducted in the same manner as in Example 1 except that the main agent A was added so as to have a concentration of 25% by mass. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Example 12)
A dissolution removal composition was prepared and a solubility test was conducted in the same manner as in Example 1 except that the dissolution accelerator A was added so that the concentration was 0.02% by mass. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Comparative Example 1)
(B) Instead of the dissolution accelerator A, the concentration of the dissolution accelerator D (cationic amine derivative and surfactant, trade name: Asahi ACI-602, manufactured by Asahi Chemical Industry Co., Ltd.) is 0.1% by mass. A dissolution removal composition was prepared and a solubility test was performed in the same manner as in Example 5 except that the dissolution removal composition was prepared. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 2)
(B) Instead of the dissolution accelerator A, the concentration of the dissolution accelerator E (cationic amine derivative and surfactant, trade name: Asahi ACI-10B, manufactured by Asahi Chemical Industry Co., Ltd.) is 0.1% by mass. A dissolution removal composition was prepared and a solubility test was performed in the same manner as in Example 5 except that the dissolution removal composition was prepared. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 3)
(B) Example except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator F (oxalic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass instead of the dissolution accelerator A. In the same manner as in No. 5, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 4)
(B) Example 5 except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator G (formic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass instead of the dissolution accelerator A. In the same manner as above, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 5)
(B) Example except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator H (malonic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass instead of the dissolution accelerator A. In the same manner as in No. 2, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 6)
(B) Example except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator I (glyoxalic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass instead of the dissolution accelerator A. In the same manner as in No. 2, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 7)
(B) Example except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator J (glyoxylic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass instead of the dissolution accelerator A. In the same manner as in No. 5, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 8)
(B) Example except that the dissolution removal composition was prepared so that the concentration of the dissolution accelerator K (glycolic acid, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.5% by mass instead of the dissolution accelerator A. In the same manner as in No. 5, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 9)
(B) A dissolution removal composition was prepared by adding so that the concentration of the dissolution accelerator L (ethylene glycol, manufactured by Wako Pure Chemical Industries, Ltd.) was 0.1% by mass in place of the dissolution accelerator A. In the same manner as in Example 2, a dissolution removal composition was prepared and a solubility test was performed. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 10)
(B) In place of dissolution accelerator A, dissolution accelerator M (iron powder, manufactured by Wako Pure Chemical Industries, Ltd.) is dissolved and removed so as to be 0.1% by mass with respect to the total mass of the dissolution composition. A dissolution removal composition was prepared and a solubility test was carried out in the same manner as in Example 2 except that was prepared. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Comparative Example 11)
(B) In place of dissolution accelerator A, dissolution accelerator M (iron powder, manufactured by Wako Pure Chemical Industries, Ltd.) is added and dissolved so as to be 0.1% by mass with respect to the total mass of the dissolution removal composition. A dissolution removal composition was prepared and a solubility test was performed in the same manner as in Example 2 except that the removal composition was prepared and the dissolution inhibitor was not added. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 12)
(B) A dissolution / removal composition was prepared in the same manner as in Example 2 except that the dissolution / removal composition was prepared by adding so that the concentration of the main agent A was 0.05% by mass. Carried out. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

(Comparative Example 13)
(B) A dissolution / removal composition was prepared and dissolved in the same manner as in Example 2 except that the dissolution / removal composition was prepared by adding the dissolution accelerator A to a concentration of 0.001% by mass. The test was conducted. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 14)
(B) A dissolution removal composition was prepared and a solubility test was conducted in the same manner as in Example 2 except that the dissolution accelerator A was not added. The amount of each component is shown in Table 2 below. The results of the solubility test are shown in FIGS.

(Comparative Example 15)
A dissolution removal composition was prepared and a solubility test was conducted in the same manner as in Example 5 except that the dissolution accelerator B was added so as to have a concentration of 35% by mass. The amount of each component is shown in Table 1 below. The results of the solubility test are shown in FIGS.

In addition, it shows below about each component of Table 1.
Main agent A: 1-hydroxyethane-1,1-diphosphonic acid Main agent B: Aminotris (methylenephosphonic acid)
Main agent C: ethylenediaminetetrakis (methylenephosphonic acid)
Dissolution promoter A: FeO
Dissolution promoter B: Fe (OH) ₂
Dissolution promoter C: Fe ₃ O ₄
Dissolution accelerator D: Cationic amine derivative and surfactant (trade name: Asahi ACI-602, manufactured by Asahi Chemical Industry Co., Ltd.)
Dissolution promoter E: Cationic amine derivative and surfactant (trade name: Asahi ACI-10B, manufactured by Asahi Chemical Industry Co., Ltd.)
Dissolution accelerator F: oxalic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Dissolution promoter G: formic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Dissolution accelerator H: Malonic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Solubilizer I: Glyoxalic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Solubilizer J: Glyoxylic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Dissolution accelerator K: glycolic acid, manufactured by Wako Pure Chemical Industries, Ltd.)
Dissolution accelerator L: Ethylene glycol, manufactured by Wako Pure Chemical Industries, Ltd.)
Dissolution promoter M: Iron powder Reducing agent A: Ascorbic acid, manufactured by Kishida Chemical Co., Ltd.)
Reducing agent B: Elsorbic acid Corrosion inhibitor: Betaine surfactant (trade name: Ademin # 2304, manufactured by Kyoeisha Chemical)

As can be seen from Table 1 and FIG. 2, according to the dissolution removal composition according to the present invention, since it contains (A) the main agent and (B) the dissolution accelerator, the dissolved iron concentration immediately after the start of the solubility test. It can be seen that the scale is dissolved and the scale is rapidly dissolved (Example 1 to Example 12: see solid line L1-L12 in FIG. 2). This result is because (B) Fe ₃ O ₄ of the magnetite powder was reduced and dissolved by the reducing power of the dissolution accelerator, so that immediately after the magnetite powder was immersed in the dissolution removal composition, the dissolved iron concentration increased. it is conceivable that. On the other hand, in the case where (B) a dissolution accelerator containing iron oxide containing divalent iron is not included, the increase in the dissolved iron concentration after the start of the solubility test is slow, and the dissolution of the scale starts. It can be seen that the rate and the dissolution rate are slow (Comparative Examples 1-9 and 11-14: see dotted lines L21-29 and 31-35 in FIG. 2). This result is considered to be because the solubility of Fe ₃ O _{4 in} the magnetite powder was not sufficiently obtained because it did not contain a dissolution accelerator containing an iron oxide containing divalent iron.

In addition, as shown in FIG. 3, in the dissolution removal composition according to the present invention, the oxidation-reduction potential may quickly decrease to −0.2 V or less (vs. SSE) immediately after the start of the solubility test. I understand. The result is (Example 1-Example 12: see solid line L1-L12 in FIG. 3). This result is considered because the oxidation-reduction potential rapidly decreased due to the reducing power of the (B) dissolution accelerator containing iron oxide. On the other hand, in the case where (B) the dissolution accelerator containing iron oxide is not included, it can be seen that in any case, the reduction in redox potential is slow, and the dissolution rate and dissolution rate of the scale are slow (Comparative Example). 1—Comparative Example 14: See dotted lines L21-29 and 31-34 in FIG. This result is considered to be because the solubility of Fe ₃ O _{4 in} the magnetite powder was not sufficiently obtained because it did not contain a dissolution accelerator containing iron oxide.

  Furthermore, as shown in Table 1 and FIG. 4, it can be seen that the dissolution weight loss composition according to the present invention has a small corrosion weight loss. This result is considered that the weight loss by corrosion could be reduced because the scale was rapidly removed by the reduction of the scale by the (B) dissolution accelerator. On the other hand, when the (B) dissolution promoter containing iron oxide is not included, it can be seen that the corrosion weight loss is large (Comparative Example 1 to Comparative Example 15). This result is considered that (B) the reduction effect of the scale by the dissolution accelerator was not obtained, and the corrosion weight loss increased. Thus, according to this invention, it turns out that the melt | dissolution removal composition which is excellent in the melt | dissolution start rate and melt | dissolution rate of a scale, and can reduce the corrosion weight loss of a metal base material is realizable.

11 Metal piping 12 Scale 12a Surface 13 Dissolving removal composition

Claims (8)

(A) 0.1 mass% or more and 30 mass% or less of a main ingredient containing a phosphonic acid-based chelating agent, and (B) 0.010 mass% or more of a dissolution accelerator containing an iron oxide having divalent iron. ,
A dissolution removal composition comprising: The dissolution removal composition according to claim 1, wherein the iron oxide having divalent iron includes at least one selected from the group consisting of FeO, Fe ₃ O ₄ and Fe (OH) ₂ .   Phosphonic acid-based chelating agents include 1-hydroxyethane-1,1-diphosphonic acid, aminotris (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), hexamethylenediaminetetrakis (methylenephosphonic acid), diethylenetetraminepentakis ( Methylene phosphonic acid), and phosphonic acids composed of 2-phosphonobutane-1,2,4-tricarboxylic acid, and at least one selected from the group consisting of salts of the phosphonic acids. The dissolution removing composition according to 1.   The dissolution removal composition according to any one of claims 1 to 3, further comprising (C) a reducing agent.   (C) The dissolution removal according to claim 4, wherein the reducing agent is at least one selected from the group consisting of ersorbic acid, gallic acid, pyrogallol, hydrazine, ascorbic acid, a sulfur-based reducing agent, and thioureas. Composition.   The sulfur-based reducing agent comprises at least one selected from the group consisting of sulfites, hydrogen sulfites, pyrosulfites, thiosulfates, dithionites, thionates, polythionates, and thiourea dioxide. 5. The dissolution removal composition according to 5.   The dissolution removal composition according to claim 5, wherein the thiourea comprises at least one selected from the group consisting of alkylthiourea and guanylthiourea.   Furthermore, (D) The dissolution removal composition of any one of Claims 1-7 containing a corrosion inhibitor.

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