JP2010070805A - Descaling and rust-preventive agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a descaling and rust-preventive agent with the use of an organic phosphonic acid or a salt thereof, which shows an enhanced rust-removing effect, is less corrosive and shows improved surface finishing properties for a metal to be cleaned of which the rust has been removed. <P>SOLUTION: The descaling and rust-preventive agent contains the following components (A) to (C). The component (A) includes at least one component selected from the organic phosphonic acids and the salts thereof. The component (B) includes at least one component selected from carboxylic acids and salts thereof. The component (C) includes at least one component selected from mercapto carboxylic acids and salts thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a scale removal / rust inhibitor. More specifically, the present invention relates to a scale removal / rust preventive agent that dissolves and removes a scale containing a metal oxide generated on the surface of a metal, while suppressing corrosion of the metal and also having an excellent rust prevention effect.

  Conventionally, various scale removers have been used.

  In general, inorganic acids are characterized by low cost and high ability to dissolve metal oxides. However, on the other hand, depending on the material type of the metal to be cleaned, problems such as peracid cleaning, hydrogen embrittlement, and metal discoloration may occur. Furthermore, neutralization after washing is difficult, and since it is strongly acidic, there is a danger in handling, and there are problems such as contamination of surrounding facilities and environment due to generation of gas and mist.

  In order to avoid the above problem in the scale remover mainly composed of an inorganic acid, cleaning with an organic acid is performed. A scale remover mainly composed of an organic acid is expensive and has a disadvantage that it needs to be heated to 70 ° C. or higher during washing because of its low scale dissolving ability at room temperature. In comparison, the corrosive action on the metal to be cleaned is moderate, and neutralization after cleaning is easy.

  Among scale removers mainly composed of organic acids, those mainly composed of organic phosphonic acids and salts thereof are particularly attracting attention because they can dissolve iron oxide in a neutral pH range.

  However, simply using organic phosphonic acid cannot avoid the corrosion of the metal to be cleaned, and even if a normal corrosion inhibitor is used in combination, the scale removal ability and the corrosion inhibitory effect are always well balanced. It is not possible.

For example, Patent Document 1 below discloses that an organic phosphonic acid can be an effective rust remover by adding a reducing agent, a corrosion inhibitor, and a surfactant. Further, Patent Document 2 below discloses an aqueous solution of a tertiary alkanolamine salt of 1-hydroxyethylidene-1,1-diphosphonic acid, which is adjusted to pH 5.0 to 8.5. ing.
U.S. Pat. No. 4,810,405 However, according to the research of the present inventor, Patent Document 1 using benzotriazole as a corrosion inhibitor together with organic phosphonic acid is, for example, 1-hydroxy like that of Patent Document 2 as organic phosphonic acid. Even when ethylidene-1,1-diphosphonic acid or a salt thereof is used, there is a problem that the degree of corrosion increases and it is difficult to say that the rust removal property is effective.

  That is, with the conventional scale remover described above, even if the scale containing the metal oxide generated on the surface of the metal can be dissolved and removed, the corrosion of the metal cannot be sufficiently suppressed. In addition, from such a point, after the treatment with the scale remover, it is necessary to perform a corrosion inhibition treatment (neutralization step) and washing with water, which is troublesome, reduces work efficiency, and increases the burden on the worker. .

  Therefore, the present invention provides an excellent rust preventive by simultaneously inhibiting the corrosion of metal when using organic phosphonic acid or its salt such as 1-hydroxyethylidene-1,1-diphosphonic acid or its salt for scale removal. It is a technical problem to be solved to provide a scale removal / rust preventive agent that can provide an effect.

  As a result of accumulating various experiments to solve the above problems, the inventor of the present application, as an active ingredient used together with an organic phosphonic acid or a salt thereof, one or more selected from a carboxylic acid and a salt thereof, a mercaptocarboxylic acid and a salt thereof As a result, the present invention has been completed.

(First invention)
The configuration of the first invention of the present application for solving the above-mentioned problems is a scale removal / rust inhibitor that contains the following components (A) to (C) and is adjusted within a pH range of 5 to 8. .
(A) component: 1 or more types chosen from organic phosphonic acid and its salt.
(B) component: 1 or more types chosen from carboxylic acid and its salt.
(C) component: 1 or more types chosen from mercaptocarboxylic acid and its salt.

  In the present invention, “mercaptocarboxylic acid” refers to a compound having at least one mercapto group (—SH) and at least one carboxyl group (—COOH). Further, among mercaptocarboxylic acids, a compound having one mercapto group and two carboxyl groups is referred to as “mercaptodicarboxylic acid”.

  When the scale removing / rust preventive agent of the first invention described above is used, scale containing metal oxides generated on the surface of the metal can be dissolved and removed, while corrosion of the metal is suppressed and excellent rust prevention is achieved. An effect can be obtained.

  That is, while the scale on the metal surface can be removed well, the metal corrosion is significantly less than that of the acid-based cleaning liquid described above, and compared with the case where organic phosphonic acid and benzotriazole are used as in Patent Documents 1 and 2. The corrosion is small enough. Therefore, it is not necessary to perform neutralization and rust prevention using another liquid after the treatment.

  In addition, the scale removing / rust preventive agent of the first invention is adjusted to a neutral pH by blending an appropriate pH adjuster such as NaOH (caustic soda), for example, which is the effect of the above-described invention. It is safe for workers as well.

  The reason why the above-described excellent effect is obtained by the scale removal / rust preventive agent of the first invention and the mechanism of its action are not necessarily completely clarified, but at least the following points (1) to (3) Can be pointed out.

  (1) The organic phosphonic acid or salt thereof as the component (A) acts as a scale removing component and a rust preventive component. The carboxylic acid or salt thereof as the component (B) acts as a scale removing component. The mercaptocarboxylic acid or salt thereof as the component (C) is a corrosion inhibitor, but has a characteristic action of being a corrosion inhibitor that does not impair the scale removal performance of the components (A) and (B).

  (2) The antirust action of the component (A) is related to the formation of a rust-preventing film of an organic phosphonic acid metal salt by combining the organic phosphonic acid or its salt with the metal material to be treated after the scale removal. Yes.

  (3) In addition, although the mercaptocarboxylic acid and its salt which are (C) components are corrosion inhibitors excellent in terms of environmental load etc., their rust removal performance is inferior when used alone. However, when a mercaptocarboxylic acid or a salt thereof is blended together with the component (A) and the component (B), the rust removal effect is enhanced, and the treated metal surface after the rust removal can be finished beautifully. Further, when mercaptodicarboxylic acid is used as the mercaptocarboxylic acid, the odor is effectively reduced.

(Second invention)
The constitution of the second invention of the present application for solving the above problem is that the component (A) according to the first invention is one or more selected from 1-hydroxyethylidene-1,1-diphosphonic acid and salts thereof, Descaler / rust inhibitor.

  (A) Although the kind of organic phosphonic acid and its salt which are components is not limited, 1-hydroxy ethylidene-1, 1- diphosphonic acid and its salt are especially preferable so that it may prescribe | regulate in 2nd invention.

(Third invention)
The configuration of the third invention of the present application for solving the above-mentioned problem is that the component (B) according to the first invention or the second invention is at least one selected from oxycarboxylic acid and salts thereof, scale removal / prevention It is a rusting agent.

  (B) Although the kind of carboxylic acid which is a component, or its salt is not limited, as prescribed | regulated to 3rd invention, oxycarboxylic acid and its salt are especially preferable.

(Fourth invention)
The constitution of the fourth invention of the present application for solving the above problem is that the component (C) according to any one of the first invention to the third invention is one or more selected from mercaptodicarboxylic acid and a salt thereof. Remover / rust inhibitor.

  The type of mercaptocarboxylic acid and salt thereof as component (C) is not limited, but mercaptodicarboxylic acid and salts thereof are particularly preferred from the viewpoint of reducing odor during use, as defined in the fourth invention.

(Fifth invention)
The configuration of the fifth invention of the present application for solving the above problem is a scale removal / rust preventive agent in which the mercaptodicarboxylic acid and its salt according to the fourth invention are thiomalic acid and its salt.

  As the mercaptodicarboxylic acid or a salt thereof, thiomalic acid or a salt thereof is particularly preferable as defined in the fifth invention from the viewpoint of rust removal performance and the reduction of odor during use.

  According to the present invention, there is provided a scale removal / rust preventive agent that dissolves and removes a scale containing a metal oxide generated on the surface of a metal, while suppressing corrosion of the metal and also having an excellent rust prevention effect. The

  Next, an embodiment of the present invention including the best embodiment will be described.

[Descaler / Rust preventive]
The scale removal / rust preventive agent of the present invention includes at least one component selected from (A) component: organic phosphonic acid and a salt thereof, and one or more components selected from component (B): carboxylic acid and a salt thereof, (C) component: 1 or more types chosen from mercaptocarboxylic acid and its salt are contained.

Moreover, the scale removal / rust preventive agent is adjusted within the range of pH 5-8. Such pH adjustment can be performed, for example, by blending an appropriate pH adjusting agent, if necessary. type of pH adjusting agent is not limited, preferred pH adjusting agent, NaOH, KOH, inorganic alkali and aqueous ammonia such as _Na 2 CO _3, amines and the like.

[(A) component: one or more selected from organic phosphonic acids and salts thereof]
The kind of organic phosphonic acid and its salt to be contained in the scale removal / rust inhibitor is not limited. Particularly preferred organic phosphonic acids include 1-hydroxyethylidene-1,1-diphosphonic acid, triaminomethylphosphonic acid, aminotrimethylenephosphonic acid, aminotrimethylenephosphonic acid pentasodium salt, 1-hydroxyethylidene-1,1-diphosphonic acid 1-hydroxyethylidene-1,1-diphosphonic acid trisodium salt, 1-hydroxyethylidene-1,1-diphosphonic acid tetrasodium salt, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid 7sodium, and the like. In particular, 1-hydroxyethylidene-1,1-diphosphonic acid is preferable. These organic phosphonic acid salts are also preferred.

  Preferred examples of the organic phosphonic acid salt include metal salts, ammonium salts, amine salts and the like of various organic phosphonic acids. More specifically, in the case of 1-hydroxyethylidene-1,1-diphosphonic acid, its tertiary alkanolamine salt, inorganic alkali salt, ammonium salt and the like are exemplified.

  The total content of the organic phosphonic acid and its salt in the scale removal / rust preventive agent is not limited, but is usually 0.1% by mass or more, preferably 0.5 to 50% by mass, more preferably 1 to 1%. 30% by weight. If the content is less than 0.1% by mass, the effect of the present invention may not be ensured due to a lack of absolute amount. Even if the content exceeds 50% by mass, the effect of the invention is saturated, which is disadvantageous in terms of cost.

[Component (B): one or more selected from carboxylic acids and salts thereof]
Although the kind of carboxylic acid and its salt to be contained in the scale removal / rust preventive is not limited, hydroxycarboxylic acid, dicarboxylic acid or its salt is particularly preferable.

  Examples of the hydroxycarboxylic acid and salts thereof include citric acid, malic acid, tartaric acid, and salts thereof, and examples of the dicarboxylic acid and salts thereof include oxalic acid, malonic acid, succinic acid, and salts thereof.

  The total content of the carboxylic acid and the salt thereof in the scale removal / rust inhibitor is not particularly limited, but is usually 0.1% by mass or more, preferably 0.5 to 30% by mass, and more preferably 1 to 1%. 10% by mass. If the content is less than 0.1% by mass, the effect of the present invention may not be ensured due to a lack of absolute amount. Even if content exceeds 30 mass%, the effect of invention is saturated and it is disadvantageous in cost.

[Component (C): one or more selected from mercaptocarboxylic acids and salts thereof]
The type of mercaptocarboxylic acid and its salt to be contained in the scale removal / rust preventive is not limited, but thiomalic acid (that is, mercaptosuccinic acid) and thioglycolic acid (that is, mercaptoacetic acid) are particularly preferred.

  Preferred examples of the mercaptocarboxylic acid salt include various metal salts, ammonium salts, and amine salts of mercaptocarboxylic acids. Examples of salts of thioglycolic acid include sodium thioglycolate, calcium thioglycolate, potassium thioglycolate, ammonium thioglycolate, monoethanolamine thioglycolate, diethanolamine thioglycolate, triethanolamine thioglycolate, Examples include ethylamine thioglycolate, monoisopropanolamine thioglycolate, and triisopropanolamine thioglycolate.

  Among mercaptocarboxylic acids and salts thereof, mercaptodicarboxylic acids and salts thereof are particularly preferable. Among the mercaptodicarboxylic acids and salts thereof, the above-described thiomalic acid and salts thereof are particularly preferable. Examples of the salt of thiomalic acid include sodium thiomalate, ammonium thiomalate, monoethanolamine thiomalate, diethanolamine thiomalate, triethanolamine thiomalate, and the like.

  The total content of mercaptocarboxylic acid and its salt in the scale removal / rust inhibitor is not particularly limited, but is generally preferably in the range of 0.1 to 20.0% by mass. If the content is less than 0.1% by mass, the effect of the present invention may not be ensured due to a lack of the absolute amount, and even if the content exceeds 20.0% by mass, the effect of the present invention is saturated and costly. Disadvantageous. The content of mercaptocarboxylic acid and its salt is particularly preferably in the range of 0.5 to 5.0% by mass.

[Other components in scale remover / rust inhibitor]
In addition to the above-described pH adjuster, organic phosphonic acid or salt thereof, carboxylic acid or salt thereof, mercaptocarboxylic acid or salt thereof, the scale remover / rust preventive agent includes a reducing agent (for example, about 1 to 30% by mass). (Sodium sulfite, isoascorbic acid, L-ascorbic acid, glucose, hydrazine, etc.) can be contained.

  In order to further enhance the scale removal performance, the scale removal / rust preventive may contain a surfactant as necessary. As the type of surfactant, one or more of nonionic, anionic, cationic, and zwitterionic types can be appropriately selected and contained, and the content is 0.5% by mass or less. It is preferable.

  Further, the descaling / rust preventive agent may contain various known components that may be contained in this type of preparation within a range that does not impair the effects of the invention. For example, a chelating agent can also be included for the purpose of extending the life of the scale removal / rust inhibitor. Examples of the chelating agent include metal salts such as ethylenediaminetetraacetic acid, hydroxyethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, amine salts, ammonium salts, and the like within a range of about 0.1 to 10.0% by mass. It can be included.

  Next, examples of the present invention will be described. The technical scope of the present invention is not limited by the following examples.

[Preparation of scale removal and rust preventive]
Scale removal / rust preventive liquids having compositions according to Examples 1 to 10 and Comparative Examples 1 to 10 shown in Table 1 at the end were prepared. About each Example and each comparative example in a table | surface, the compounding quantity of the component was described with the numerical value (mass%) in the compounding component column. The compounding ingredient column is arranged and classified according to ingredient categories. For example, the part described as “component (A) or component (A ratio)” describes the organic phosphonic acid or salt thereof as component (A) or a component for comparison thereto. The remainder of the composition other than the mass% component shown in the table is water. The pH of these scale removal / rust preventive solutions was adjusted using a pH adjuster (caustic soda) as shown in the table.

[Preparation of rust test sample]
SKD61 cylindrical block material A 15 mm radius x 30 mm height was degreased with an organic solvent, and then this SKD61 block material was subjected to a salt water spray test in accordance with JIS K2246 5.35. %, Spray amount 1.0-2.0 ml / hr / 80 cm ² , 24 hours). A predetermined number of rust test samples were prepared.

[Test method and evaluation]
Using the above rust test samples, the scale removal / rust preventive agent according to each of the above examples and comparative examples was evaluated for “cleanability”, “corrosion inhibition”, and “rust prevention” as follows. did.

  That is, with regard to cleaning properties, 500 ml of each of the scale removal / rust preventive test solutions according to each of the examples and the comparative examples was placed in a circular container at 400 r. p. m. The above rust test sample was immersed in this test solution for 60 minutes while rotating at a stirring speed of, and the detergency (rust removal property) was visually observed.

  In addition, for the evaluation of corrosion inhibition, in the evaluation of the above “cleanability”, before and after the immersion, when the rust test sample was immersed in the test solution of the scale removal / rust inhibitor according to each Example and each Comparative Example This was done by determining the weight change.

  Furthermore, for rust prevention evaluation, after immersing the rust test samples for 1 hour in the test solution of the scale removal / rust prevention agent according to each example and each comparative example, the rust test samples are stored for 7 days. Every 7 days, the occurrence of rust was visually observed.

  The evaluation standard for detergency (rust removability) is “4” for rust removal rate of 90% or more with respect to the area where rust was generated in the rust test sample, 70% or more and less than 90% rust. The removal rate was evaluated as “3”, the rust removal rate of 50% or more and less than 70% was evaluated as “2”, and the rust removal rate of less than 50% was evaluated as “1”.

  The evaluation standard for corrosion inhibition is “4” for the weight change of the above rust test sample is less than 1%, “3” for the weight change of 1% or more and less than 5%, and “5” or more and less than 10%. Some were “2” and 10% or more were “1”.

  The evaluation standard of rust prevention property is “4” when the rust generation area is 90% or more and “3” when 70% or more and less than 90% in the visual observation of rust generation after 7 days. “50% or more and less than 70%” was designated as “2”, and less than 50% was designated as “1”.

  According to the present invention, it is possible to enhance the derusting effect in the scale removal / rust preventive agent using organic phosphonic acid or a salt thereof, reduce the degree of corrosion, and improve the surface finish of the metal to be cleaned after derusting. Become.

Claims (5)

A scale removing / rust preventive agent comprising the following components (A) to (C) and being adjusted within a pH range of 5 to 8.
(A) component: 1 or more types chosen from organic phosphonic acid and its salt.
(B) component: 1 or more types chosen from carboxylic acid and its salt.
(C) component: 1 or more types chosen from mercaptocarboxylic acid and its salt. The scale removal / rust inhibitor according to claim 1, wherein the component (A) is one or more selected from 1-hydroxyethylidene-1,1-diphosphonic acid and a salt thereof. The scale removal / rust preventive agent according to claim 1 or 2, wherein the component (B) is at least one selected from oxycarboxylic acids and salts thereof. The scale removal / rust preventive agent according to any one of claims 1 to 3, wherein the component (C) is one or more selected from mercaptodicarboxylic acids and salts thereof. The scale removal / rust preventive agent according to claim 4, wherein the mercaptodicarboxylic acid and a salt thereof are thiomalic acid and a salt thereof.