JP5972749B2 - Scale cleaning liquid composition and scale cleaning method - Google Patents

Description

  The present invention relates to a scale cleaning liquid composition and a scale cleaning method for removing scale adhered to a heat transfer portion such as a cooling water system and a boiler water system.

  In water systems with heat transfer parts, such as cooling water systems and boiler water systems, in recent years, from the standpoint of resource saving and energy saving, there are cases in which the discharge (blow) of water outside the system is reduced and operation is performed in a highly concentrated state. It has increased. When such an operation is performed, the salt that becomes a scale factor such as calcium, magnesium, and silica dissolved in the aqueous system also becomes high in concentration, so that the generation of scale in the heat transfer part of the aqueous system is accelerated. There is a possibility.

  Since the generated scale may cause troubles in the operation of the cooling water system, the boiler water system, and the like, such as a decrease in heat exchange efficiency and blockage of piping, it is desirable to remove the scale by washing immediately.

  Scale components generated in cooling water systems, boiler water systems, etc. include calcium carbonate, calcium sulfate, calcium sulfite, calcium phosphate, calcium silicate, magnesium silicate, magnesium hydroxide, etc. It becomes.

  As a method for removing such scale, Patent Document 1 examined a method using an inorganic acid such as hydrochloric acid and sulfamic acid, and an organic carboxylic acid such as citric acid and glycolic acid. Methods using carboxylic acid polymers have been studied. Further, in Patent Document 3, a solid toilet scale inhibitor in which an organic acid, a vinylpyrrolidone polymer, and a polycarboxylic acid salt such as a sodium salt of an isoamylene-maleic anhydride copolymer are blended as a solid acid is studied. ing.

  However, the method using an inorganic acid and an organic carboxylic acid disclosed in Patent Document 1 has a problem that the pH of the cleaning liquid is lowered, so that the metal portion of the aqueous system is significantly corroded. In addition, since the method using the water-soluble carboxylic acid polymer of Patent Document 2 has a weak scale cleaning effect with the polymer alone, the load (COD load, etc.) of the cleaning waste liquid on the environment increases as the concentration of addition increases. There is a problem that it gets bigger. The toilet scale inhibitor of Patent Document 3 is a solid, but its effect is not obtained in a short time due to its low water solubility, and when it is used as a liquid, the storage stability is poor, and the active ingredient concentration becomes dilute. There is a problem that becomes high.

JP 2000-064069 A JP-A-6-063590 JP 2003-010885 A

  An object of the present invention is to provide a scale cleaning liquid composition and a scale cleaning method that have a high scale cleaning effect, are unlikely to corrode metals, and are excellent in storage stability as a liquid preparation.

The present invention includes a sulfamic acid contains a carboxylic acid copolymer containing a monomer having a sulfonic acid group, a pH of the scale cleaning composition Ru der range of 0.2 to 2.0 is there.

  In the scale cleaning liquid composition, the carboxylic acid copolymer containing the monomer having a sulfonic acid group is preferably a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. .

  In the scale cleaning liquid composition, it is preferable that a weight average molecular weight of the carboxylic acid copolymer containing the monomer having a sulfonic acid group is in a range of 1,000 or more and less than 4,500.

Further, the present invention includes a sulfamic acid contains a carboxylic acid copolymer containing a monomer having a sulfonic acid group, pH is, the scale cleaning composition area by der of 0.2 to 2.0 This is a scale cleaning method in which an object is added to an aqueous system to which a scale is attached, brought into contact with a scale attachment site, and the scale is removed.

  In the scale cleaning method, the carboxylic acid copolymer containing a monomer having a sulfonic acid group is preferably a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid.

  In the scale cleaning method, it is preferable that the weight average molecular weight of the carboxylic acid copolymer containing the monomer having a sulfonic acid group is in a range of 1,000 or more and less than 4,500.

  In the present invention, by containing a sulfamic acid and a carboxylic acid copolymer containing a monomer having a sulfonic acid group, the scale cleaning effect is high, the metal is hardly corroded, and the storage stability as a liquid agent is excellent. A scale cleaning liquid composition and a scale cleaning method can be provided.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  The scale cleaning liquid composition according to this embodiment contains sulfamic acid and a carboxylic acid copolymer containing a monomer having a sulfonic acid group as active ingredients. By using sulfamic acid and a carboxylic acid copolymer containing a monomer having a sulfonic acid group in combination, the scale cleaning effect is high, the metal is hardly corroded, and the storage stability as a liquid agent is excellent.

The sulfamic acid is a compound represented by the following general formula (1).
R ₂ NSO ₃ H (1)
(In the formula, R is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

  As sulfamic acid, in addition to amidosulfonic acid (amidosulfuric acid) in which both two R groups are hydrogen atoms, N-methylsulfamic acid, N-ethylsulfamic acid, N-propylsulfamic acid, N-isopropylsulfamine One of two R groups such as acid and N-butylsulfamic acid is a hydrogen atom and the other is an alkyl group having 1 to 4 carbon atoms, sulfamic acid, N-dimethylsulfamic acid, N-diethylsulfamic acid, N Both of two R groups such as -dipropylsulfamic acid, N-dibutylsulfamic acid, N-methyl-N-ethylsulfamic acid, N-methyl-N-propylsulfamic acid are alkyl groups having 1 to 4 carbon atoms A certain sulfamic acid etc. are mentioned. As the sulfamic acid, it is preferable to use amidosulfuric acid from the viewpoint of environmental load.

  Examples of the carboxylic acid copolymer containing a monomer having a sulfonic acid group include (meth) acrylic acid and / or a salt thereof, maleic acid and / or a salt thereof, itaconic acid and / or a salt thereof, and the like. Monomer having a monomer having, and a sulfonic acid group such as vinyl sulfonic acid, allyl sulfonic acid, (meth) acrylamide-alkyl- and / or aryl-sulfonic acid such as 2-acrylamido-2-methylpropane sulfonic acid Examples thereof include binary copolymers obtained by copolymerization of the polymers, and ternary copolymers obtained by combining substituted (meth) acrylamide monomers such as alkylacrylamide.

  The monomer unit of (meth) acrylic acid and / or its salt is the following formula (2), and the monomer unit of (meth) acrylamide-alkyl- and / or aryl-sulfonic acid and / or its salt is In the formula (3), the monomer unit of the substituted (meth) acrylamide is represented by the following formula (4).

（２）
（式（２）中、Ｒ^１は水素原子またはメチル基を表し、Ｘ^１は水素原子、１価または２価の金属原子、アンモニウム基または有機アンモニウム基を表す。）

(2)
(In Formula (2), R ¹ represents a hydrogen atom or a methyl group, and X ¹ represents a hydrogen atom, a monovalent or divalent metal atom, an ammonium group, or an organic ammonium group.)

（３）
（式（３）中、Ｒ^２は水素原子またはメチル基を表し、Ｘ^２はアルキルスルホン酸基またはその塩、または、アリールスルホン酸基またはその塩を表し、塩の場合は１価または２価の金属塩、アンモニウム塩または有機アンモニウム塩を表す。)

(3)
(In the formula (3), R ² represents a hydrogen atom or a methyl group, X ² represents an alkyl sulfonic acid group or a salt thereof, or an aryl sulfonic acid group or a salt thereof. Represents a metal salt, an ammonium salt or an organic ammonium salt.)

（４）
（式（４）中、Ｒ^３は水素原子またはメチル基を表し、Ｘ^３とＸ^４はそれぞれ独立に水素原子またはアルキル基を表すが、少なくとも一方がアルキル基である。)

(4)
(In Formula (4), R ³ represents a hydrogen atom or a methyl group, and X ³ and X ⁴ each independently represent a hydrogen atom or an alkyl group, but at least one of them is an alkyl group.)

  As the carboxylic acid-based copolymer containing a monomer having a sulfonic acid group, from the viewpoint of storage stability of the preparation, a monomer unit of (meth) acrylic acid and / or a salt thereof, (meth) acrylamide- A binary copolymer in combination with a monomer unit of alkylsulfonic acid and / or a salt thereof, a monomer unit of (meth) acrylic acid and / or a salt thereof, and (meth) acrylamide-alkylsulfonic acid and / or Alternatively, a terpolymer obtained by combining a monomer unit of a salt thereof and a monomer unit of a substituted (meth) acrylamide is preferable, and a monomer unit of (meth) acrylic acid and / or a salt thereof and (meta ) A binary copolymer obtained by combining monomer units of acrylamide-alkylsulfonic acid and / or a salt thereof is more preferable. Among these, from the viewpoints of scale removal performance, metal corrosion inhibition, etc., a binary copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid and 2-acrylamido-2-methylpropane A terpolymer of sulfonic acid and alkylacrylamide is more preferable, and a binary copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid is particularly preferable. The compounding ratio in the said binary copolymer is 5-90: 5-50 by molar ratio, for example. The compounding ratio in the ternary copolymer is, for example, 5 to 90: 5 to 50: 5 to 50 in terms of molar ratio.

  The weight average molecular weight of the carboxylic acid-based copolymer containing a monomer having a sulfonic acid group is preferably in the range of 1,000 to less than 4,500, and in the range of 1,500 to 4,000. More preferably, it is in the range of not less than 1,500 and not more than 3,500. When the weight average molecular weight of the carboxylic acid copolymer containing a monomer having a sulfonic acid group exceeds 4,500, the scale removal performance may be deteriorated.

  The scale cleaning liquid composition according to this embodiment is used as a liquid preparation in which sulfamic acid and a carboxylic acid copolymer containing a monomer having a sulfonic acid group are dissolved in a solvent. As the solvent, water is usually used.

  The compounding ratio of the sulfamic acid and the carboxylic acid copolymer containing a monomer having a sulfonic acid group is, for example, in the range of 0.5 to 4 parts by weight with respect to 1 part by weight of sulfamic acid.

  The pH of the scale cleaning liquid composition according to this embodiment is, for example, in the range of 0.2 to 2.0, and preferably in the range of 0.4 to 1.5. When the pH of the scale cleaning liquid composition is less than 0.2, corrosion of the metal may be promoted, and when it exceeds 2.0, the scale removal performance may be deteriorated.

  The injection amount of the scale cleaning liquid composition according to this embodiment is usually preferably set so that the total concentration of the scale cleaning liquid composition in the aqueous system is about 500 to 50,000 mg / liter. It is more preferable to set it to be about 000 mg / liter.

  Depending on the aqueous system, such as a cooling water system, it is preferable that an azole compound, which is an anticorrosive agent for copper-based metals such as copper and copper alloys, be further added to the scale cleaning liquid composition according to this embodiment. Examples of such azole compounds include benzotriazole, tolyltriazole, aminotriazole, and the like. These may be used alone or in combination. As the azole compound, benzotriazole and tolyltriazole are preferable from the viewpoint of copper corrosion inhibition performance and the like.

The compounding quantity of an azole type compound is the range of 0.01 weight part-0.2 weight part with respect to 1 weight part of sulfamic acids, for example.

  The scale cleaning liquid composition according to the present embodiment can be applied in a high-temperature water system such as a cooling water system and a boiler water system, and other water systems.

  The scale cleaning method according to this embodiment uses the scale cleaning liquid composition. For example, the scale cleaning liquid composition is added to an aqueous system to which the scale is adhered, and is brought into contact with the scale adhesion site to remove the scale. For example, the medicine may be poured into cooling water piping, boiler water piping, or the like.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Examples 1-5, Comparative Examples 1-5>
A sulfamic acid or hydrochloric acid, a carboxylic acid polymer, and benzotriazole (BTA) are dissolved in water to prepare a liquid preparation so that the blending ratio shown in Table 2 is obtained, and at room temperature (25 ° C.) or low temperature (−5 The appearance was confirmed after standing still for 7 days. Table 1 shows the types and weight average molecular weights of the carboxylic acid polymers.

  “AABI” used in the examples is an acrylic acid-based binary copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. “AATER” is an acrylic acid-based terpolymer of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and alkylacrylamide. “PAA” used in the comparative example is an acrylic acid homopolymer (polyacrylic acid), and “PMAA” is a maleic acid homopolymer (polymaleic acid).

  As in Comparative Examples 1 and 2, when hydrochloric acid is blended as an inorganic acid, white precipitation occurs, which is not desirable from the viewpoint of quality control. As in Comparative Examples 3 to 5, when an acrylic acid homopolymer (Polymer E) or a maleic acid homopolymer (Polymer F) that does not contain a sulfonic acid group is used as a polymer, the preparation becomes cloudy during low-temperature storage. Or a white precipitate is formed, which is not desirable from the viewpoint of quality control.

<Examples 6 to 10 and Comparative Examples 6 to 12>
The scale removal performance evaluation test was conducted as follows. In order to obtain the water quality shown in Table 3, calcium chloride and sodium bicarbonate were added to 4 times concentrated water of Sagamihara well water to prepare a scale adhesion solution, put in a beaker (SUS, 500 mL), and 75 ° C. After storing for 48 hours, the scale was adhered to the inner surface of the beaker. The amount of scale attached was about 300 mg per container. Next, each drug component is added to Sagamihara city water 4 times concentrated water to a predetermined concentration to prepare a cleaning test solution, put in a beaker with a scale attached, and stirred with a magnetic stirrer. The mixture was stirred for 2 hours at a speed of 300 rpm, and the weight loss of the scale before and after the test was measured.

The corrosion test was performed as follows. Using Sagamihara City 4 times concentrated water shown in Table 3 as test water for corrosion test, each drug component is added to prescribed concentration, and calcium carbonate powder is added to 500 mg / L to prepare 1 L of test solution. did. That is, in accordance with the industrial water corrosion test method (JIS-K 0100), a disk in which a metal test piece (mild steel SS400 or copper C-1220P, 10 × 30 × 50 mm, # 400) is fixed to each test solution, The mixture was stirred at 35 ° C. and a stirring rotational speed of 150 rpm for 7 days. The corrosion rate was determined by the following equation (5) from the difference between the test piece weight measured before the test was started and the test piece weight measured after the test was completed.
Corrosion rate (mdd) [mg / dm ² · d] = (weight before test−weight after test) / (surface area × test period) (5)

  From Examples 6 and 7, it was confirmed that the amount of copper corrosion can be kept low by using benzotriazole (BTA) together. From the comparison between Examples 6 to 10 and Comparative Examples 6 to 9, when a sulfamic acid and a carboxylic acid copolymer containing a monomer having a sulfonic acid group are used in combination, an inorganic acid is used alone. It can be seen that an equivalent scale removal amount can be obtained while suppressing the corrosion amount of iron lower than in the case where the inorganic acid and the organic acid are used in combination. From a comparison between Example 6 and Comparative Examples 10 and 11, it can be seen that an equivalent scale removal amount can be obtained by suppressing the polymer addition concentration (that is, COD load) lower than when the polymer is used alone. . From Comparative Example 10, it can be seen that even with the polymer alone, the corrosion rate increases as the additive concentration is increased. From the comparison between Example 7 and Comparative Example 12, it can be seen that the corrosion rate of iron can be suppressed lower when sulfamic acid is used than when hydrochloric acid is used.

Claims (6)

And sulfamic acid contains a carboxylic acid copolymer containing a monomer having a sulfonic acid group, pH is, the scale cleaning composition, wherein the range der Rukoto of 0.2 to 2.0 . It is a scale washing | cleaning liquid composition of Claim 1, Comprising:
A scale cleaning liquid composition, wherein the carboxylic acid copolymer containing a monomer having a sulfonic acid group is a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. The scale cleaning liquid composition according to claim 1 or 2,
The scale cleaning liquid composition, wherein a weight average molecular weight of the carboxylic acid copolymer containing a monomer having a sulfonic acid group is in a range of 1,000 or more and less than 4,500. And sulfamic acid contains a carboxylic acid copolymer containing a monomer having a sulfonic acid group, pH is a scale cleaning composition Ru der range of 0.2 to 2.0, scale is deposited A scale cleaning method comprising removing the scale by adding it to the water system and bringing it into contact with the scale adhesion site. The scale cleaning method according to claim 4,
A scale cleaning method, wherein the carboxylic acid-based copolymer containing a monomer having a sulfonic acid group is a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. A scale cleaning method according to claim 4 or 5,
The scale cleaning method, wherein a weight average molecular weight of the carboxylic acid copolymer containing the monomer having a sulfonic acid group is in a range of 1,000 or more and less than 4,500.