Method for corrosion protection of metals in aqueous systems

Abstract

A method for preventing metal corrosion in water systems is provided, which minimizes the use of phosphorus compounds or metal salt compounds that contribute to eutrophication or water toxicity, thus reducing their impact on the aquatic environment, and is applicable to a wide range of water qualities. This invention provides a method for preventing metal corrosion in water systems using: a copolymer of (meth)acrylic acid monomer and a sulfonic acid-containing monomer, and an organic acid compound with an organic acid corrosion resistance index of 4 or higher.

Description

Technical Field

[0001] This invention relates to methods for preventing metal corrosion in water systems. Background Technology

[0002] In water systems such as cooling water systems, metal components are frequently used in devices and flow paths. The parts of these metal components that come into contact with water are susceptible to corrosion. For example, heat exchangers, reaction vessels, and piping made of carbon steel, copper, galvanized steel, zinc, aluminum, aluminum alloys, stainless steel, or copper alloys are prone to corrosion due to contact with cooling water. To prevent this corrosion, anti-corrosion treatments are typically applied to the metal components in the water system, especially the parts in contact with water, for example, by adding chemicals to the operating water system.

[0003] For example, to inhibit corrosion of carbon steel heat exchangers, reactors, and piping, at least one corrosion-resistant phosphorus compound selected from orthophosphate, hexametaphosphate, hydroxyethylidene diphosphonate, and phosphonobutane tricarboxylate has traditionally been added to cooling water systems. However, the use of these phosphorus compounds contributes to eutrophication in aquatic environments, and therefore, regulations restricting the discharge of phosphorus into water systems or the natural environment exist in various countries and regions. Consequently, the treatment of phosphorus compounds and wastewater treatment require considerable attention and expense.

[0004] For example, Patent Document 1 and Patent Document 2 propose methods to effectively inhibit metal corrosion while minimizing environmental problems.

[0005] Patent Document 1 discloses a method for inhibiting metal corrosion, characterized in that, in an open circulating cooling water system, the water quality is adjusted by increasing the concentration of the cooling water to a Langerier index of 1.5 or higher and [SiO2]×[CaH]≥2000 [where [SiO2] is the concentration of SiO2 in the water (mg / L) and [CaH] is the calcium hardness of the water as CaCO3 (mg / L)]. Then, a copolymer of one or more of maleic acid, maleic anhydride and their water-soluble salts with a molecular weight of 1000 to 20000 and isobutylene is added.

[0006] Patent document 2 discloses a method for inhibiting corrosion of metals in contact with an aqueous solution, which includes adding (A) a polyvalent metal ion and (B) a corrosion-preventing or adhesion-inhibiting compound to the aqueous solution.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Publication No. 04-033868

[0010] Patent Document 2: WO2010 / 062461 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] The method proposed in Patent Document 1 is limited to water quality with both high calcium hardness and high silica concentration, resulting in a narrow range of applicable water qualities and thus a problem in terms of corrosion prevention. Furthermore, while the method proposed in Patent Document 2 shows good corrosion prevention, it requires the addition of small amounts of metal salts such as aluminum, necessitating further reduction of the environmental impact on the aquatic environment.

[0013] Therefore, the main objective of this invention is to provide a metal corrosion prevention treatment technology for water systems that minimizes the use of phosphorus compounds or metal salt compounds that contribute to eutrophication or water toxicity, and can be applied to a wide range of water qualities.

[0014] Solution for solving the problem

[0015] The inventors conducted in-depth research and discovered that by combining an organic acid compound with an anti-corrosion efficacy index of 4 or higher with a polymer in aquatic systems, a technology for metal corrosion prevention treatment in aquatic systems can be provided that minimizes the impact on the aquatic environment, such as eutrophication or water toxicity, and can be applied to a wide range of water quality conditions. Therefore, the present invention is as follows.

[0016] This invention provides a method for preventing metal corrosion in water systems, which uses: a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid compound with an organic acid corrosion resistance index of 4 or higher.

[0017] In addition, the present invention can also provide a water-based metal corrosion inhibitor containing: a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid compound with an organic acid corrosion inhibitory effect index of 4 or higher.

[0018] In addition, the present invention can also provide a water-based metal corrosion inhibitor containing: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, and (C) an organic acid compound with an organic acid corrosion inhibitory effect index of 4 or higher.

[0019] Alternatively, the present invention may also provide a water treatment agent containing at least one of (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, or (C) an organic acid corrosion protection index of 4 or above, which is used for metal corrosion protection treatment in water systems in the form of (i) a combination of (A) and (C) above, or (ii) a combination of (A) to (C) above.

[0020] Alternatively, a water treatment agent for improving metal corrosion protection in water systems can be provided, which contains an organic acid compound with an organic acid corrosion protection effect index of 4 or higher, utilizing (i) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, or utilizing (ii) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer and dicarboxylic acid polymer to improve metal corrosion protection in water systems.

[0021] In addition, the present invention can also provide a method for improving the metal corrosion protection of water systems, which uses an organic acid corrosion protection effect index of 4 or higher, and utilizes (i) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, or (ii) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer and dicarboxylic acid polymer to improve the metal corrosion protection of water systems.

[0022] The effects of the invention

[0023] According to the present invention, a metal corrosion prevention treatment technology for water systems can be provided, which can minimize the use of phosphorus compounds or metal salt compounds that cause eutrophication or water toxicity and thus burden the aquatic environment, and can be applied to a wide range of water qualities. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating an example of a water system used in the method of this embodiment, such as a circulating cooling water system with a cooling tower; however, the invention is not limited thereto. Detailed Implementation

[0025] The preferred embodiments for carrying out the present invention will be described below. It should be noted that the embodiments described below illustrate one example of a representative embodiment of the present invention, and thus the scope of the present invention is not to be interpreted as narrow. Furthermore, in this specification, unless otherwise specified, percentages are expressed based on mass (mass / mass%). Additionally, the upper (and lower) limits and lower (and higher) limits of each numerical range (~) can be arbitrarily combined as needed.

[0026] 1. The water-based metal corrosion inhibitor of this embodiment

[0027] This embodiment provides a technique for metal corrosion prevention treatment in water systems. This embodiment provides a method for metal corrosion prevention treatment in water systems using a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid corrosion prevention effect index of 4 or higher (hereinafter also referred to as "corrosion-resistant organic acid compound"). In this embodiment, as a more preferred method, from the viewpoint of achieving a more synergistic and superior metal corrosion prevention effect in the water system, it is preferable to use the three components: the copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, the dicarboxylic acid polymer, and the aforementioned corrosion-resistant organic acid compound. Furthermore, in this embodiment, it is preferable to add two or all three components to the water system at a concentration of 5 mg / L or higher.

[0028] In addition, as another aspect of this embodiment, a water-based metal corrosion prevention treatment method can be provided, which uses a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, a dicarboxylic acid polymer, and an organic acid compound with an organic acid corrosion prevention effect index of 4 or higher.

[0029] Furthermore, by using the aforementioned anti-corrosion organic acid compound, and polymers and / or dicarboxylic acid polymers (more preferably combinations of these polymers) having structural units derived from (meth)acrylic acid monomers and structural units derived from monomers having sulfonic acid, this embodiment can also provide a method that exhibits superior anti-corrosion effects in water systems.

[0030] According to this embodiment, the amount of phosphorus compounds or metal salt compounds that cause eutrophication or water toxicity, which burden the aquatic environment, can be significantly reduced. These phosphorus compounds or metal salt compounds can be used as little as possible, allowing for application to a wide range of water qualities. Furthermore, by using sulfonated (meth)acrylic acid polymers and / or dicarboxylic acid polymers as polymers used in combination with the aforementioned corrosion-inhibiting organic acid compounds, this embodiment can achieve scale inhibition or prevention in water systems, and is expected to help maintain the concentration of corrosion inhibitors in water systems including heat transfer surfaces.

[0031] The method described in this embodiment can be a metal corrosion prevention method for water systems, or a scale prevention method for water systems, or a combination of both. Furthermore, this metal corrosion prevention treatment method for water systems can also be a water system operation method, thereby enabling stable operation of water systems that significantly reduce the use of phosphorus compounds or metal salt compounds, or stable operation of water systems that minimize environmental pollution problems caused by the use of phosphorus compounds or metal salt compounds. Moreover, this metal corrosion prevention treatment method for water systems exhibits excellent corrosion prevention effects even without the use of phosphorus compounds or metal salt compounds, therefore it can be applied to water systems that undergo non-phosphorus or non-metal salt compound treatment, where phosphorus or metal salt compound treatment is unnecessary. This minimizes environmental pollution problems, effectively inhibits metal corrosion in water systems, and thus contributes to the stable operation of water systems.

[0032] The following is a detailed description of this embodiment.

[0033] 1-1. Objects of metal corrosion protection in water systems

[0034] In this embodiment, the material to be protected against corrosion is not particularly limited and is a metallic material. Examples of such metallic materials include one or more selected from carbon steel, copper, galvanized steel, zinc, aluminum, aluminum alloys, stainless steel, and their alloys. Furthermore, ferrous materials are preferred among the metallic materials. Examples of ferrous materials include all ferrous materials (e.g., pure iron, carbon steel, cast iron), and more preferably, carbon steel materials commonly used in boilers and heat exchangers (e.g., STB steel pipes). It should be noted that in JIS G 0203, carbon steel is considered to have a carbon content of 0.02% by mass to about 2% by mass. More specifically, carbon steel with a carbon content of 0.25% by mass or less is considered low-carbon steel, 0.25% to 0.6% by mass is considered medium-carbon steel, and 0.6% by mass or more is considered high-carbon steel. Since low-carbon to medium-carbon steel is widely used, carbon steel with a carbon content of 0.6% by mass or less is also considered ordinary steel. Furthermore, it is believed that the carbon content of cast iron is greater than 2% by mass. In this embodiment, the corrosion resistance effect is better achieved among ordinary steel, low-carbon steel, medium-carbon steel, and more preferably low-carbon steel.

[0035] The preferred object for applying the anti-corrosion treatment of this embodiment is a metal material that comes into contact with water or a metal component that uses a metal material that comes into contact with water.

[0036] Examples of parts or devices using metal materials or metal components in a water system include various pipes, tubes, pumps, flow paths, heat exchangers, chillers, reactors, compressors, etc., and one or more of these may be selected. More specifically, these or their metal parts or components are suitable for applying the corrosion prevention treatment of this embodiment.

[0037] 1-2. Polymers

[0038] The polymer used in this embodiment is not particularly limited, but is preferably an organic polymer compound that can be used in aqueous systems. The polymer used in this embodiment can be a polymer obtained from the same monomer or a copolymer obtained from different monomers. The polymer used in this embodiment can be obtained by known manufacturing methods such as organic solvent polymerization or aqueous polymerization, or commercially available products can be used. It should be noted that the form of the polymer salt is not particularly limited, but is preferably a salt that can make the monomer and polymer water-soluble. Examples include alkali metal salts based on sodium, potassium, etc., alkaline earth metal salts based on calcium, magnesium, etc., and ammonium salts based on ammonium, primary amines to tertiary amines, etc., and one or more of these can be used.

[0039] The polymer used in this embodiment is preferably one whose corrosion-resistant effect is further improved when used in combination with the corrosion-resistant organic acid compound described later, compared to the effect before combination. As an indicator for determining the suitability of the polymer used in this embodiment, a corrosion rate (mm / y) can be used, preferably less than 0.11, more preferably less than 0.10, further preferably less than 0.08, and more preferably less than 0.06. Therefore, a better corrosion-resistant effect can be obtained when used in combination with the corrosion-resistant organic acid compound.

[0040] Examples of the aforementioned polymers include (meth)acrylic acid polymers (e.g., (meth)acrylic acid polymers with sulfonated groups) and dicarboxylic acid polymers (e.g., maleic acid polymers), and one or more selected from these can be used. Preferably, the polymer is a (meth)acrylic acid polymer (preferably a (meth)acrylic acid polymer with sulfonated groups) and / or a dicarboxylic acid polymer (preferably a maleic acid polymer or an epoxy succinic acid polymer), and more preferably a combination of (meth)acrylic acid polymers and dicarboxylic acid polymers. Using both in combination provides a better corrosion protection effect. Therefore, a better corrosion protection effect can be obtained when used in combination with corrosion-resistant organic acid compounds. Furthermore, the combined use of sulfonated (meth)acrylic acid polymers (more preferably sulfonated acrylic polymers) with corrosion-resistant organic acid compounds and / or with different polymers can better inhibit scale buildup on the heat transfer surface and also better reduce water turbidity in the water system.

[0041] 1-2-1. (Meth)acrylic polymers

[0042] The polymer used in this embodiment is preferably a (meth)acrylic acid polymer, more preferably a (meth)acrylic acid copolymer, and more specifically, preferably a copolymer of (meth)acrylic acid monomer and sulfonated monomer, further preferably a copolymer of (meth)acrylic acid monomer and monomer containing amide and sulfonation groups and / or a copolymer of (meth)acrylic acid monomer and monomer containing hydroxyl and sulfonation groups. Therefore, when used in combination with a corrosion-resistant organic acid compound, a better corrosion-resistant effect can be obtained. The monomer ratio (molar ratio (mol%)) of the aforementioned (meth)acrylic acid copolymer to the sulfonated monomer is preferably 99 to 1:1 to 99. The aforementioned (meth)acrylic acid copolymer is preferably of low molecular weight. It should be noted that the (meth)acrylic acid polymer can be a water-soluble salt, and the salt described in the above polymer description can be appropriately used.

[0043] <(meth)acrylic acid monomer>

[0044] The aforementioned (meth)acrylic acid monomers are not particularly limited, and examples include (meth)acrylic acid and its salts, etc., and one or more selected from these groups can be used. In this embodiment, "(meth)acrylic acid" refers to at least one selected from the group consisting of "acrylic acid" and "methacrylic acid". Among them, acrylic acid or its salts are preferred. It should be noted that, in the case of (meth)acrylic acid monomers used in this embodiment, if a sulfonate group is contained, it is preferably used as the <sulfonic acid monomer> described later. In this case, the aforementioned (meth)acrylic acid monomer is preferably a (meth)acrylic acid monomer other than "(meth)acrylic acid monomers containing a sulfonate group".

[0045] <Sulfonic acid monomer>

[0046] The aforementioned sulfonic acid monomer is not particularly limited, but from the viewpoint of achieving better corrosion protection, a monomer containing a sulfonyl group is preferred, and this monomer is further preferred to be an unsaturated monomer. Examples of the aforementioned sulfonic acid monomers include, for example, monoene unsaturated sulfonic acid monomers, but it is not limited to this. In addition, monoene unsaturated sulfonic acid monomers may also be in the form of salts (e.g., sodium salts).

[0047] Examples of sulfonic acid monomers include monomers having amide and sulfonyl groups (preferably monomers having amide and sulfonyl groups with 6 to 9 carbon atoms), monomers having hydroxyl and sulfonyl groups (preferably monomers having hydroxyl and sulfonyl groups with 6 to 9 carbon atoms), sulfonates of aliphatic conjugated dienes (preferably sulfonates of aliphatic conjugated dienes with 4 to 15 carbon atoms), and their salts. One or more monomers selected from these groups can be used. Among these, monomers having amide and sulfonyl groups (preferably monomers having amide and sulfonyl groups with 6 to 9 carbon atoms) and / or monomers having hydroxyl and sulfonyl groups (preferably monomers having hydroxyl and sulfonyl groups with 6 to 9 carbon atoms) are preferred. Furthermore, the "sulfonyl" group of this monomer can be a sulfonyl group that may have substituents, such as alkyl sulfonyl groups, wherein the "alkyl" group of the alkyl sulfonyl group preferably has 1 to 8 carbon atoms, and more preferably methylpropanesulfonyl (also known as tert-butylsulfonyl). Therefore, when used in combination with anti-corrosion organic acid compounds, better anti-corrosion and anti-scaling effects can be obtained.

[0048] Examples of monomers having amide and sulfonyl groups include (meth)acrylamide alkyl propanesulfonic acid, crotonamide alkyl propanesulfonic acid, etc. More specifically, examples include 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 3-acrylamido-3,3-dimethylpropanesulfonic acid, etc., and their salts, etc. One or more selected from these groups may be used.

[0049] Examples of monomers having hydroxyl and sulfonyl groups include, for example, 3-allyloxy-2-hydroxy-1-propanesulfonic acid (HAPS), 3-methacryloxy-2-hydroxypropanesulfonic acid, 3-allyloxy-1-hydroxypropane-2-sulfonic acid, 3-methacryloxy-1-hydroxypropane-2-sulfonic acid, and their salts; one or more selected from these groups may be used.

[0050] Examples of sulfonated aliphatic conjugated dienes include sulfonated 1,3-butadiene and sulfonated 2,3-dimethyl-1,3-butadiene, and one or more selected from these groups may be used.

[0051] More preferred sulfonic acid monomers include sulfonyl unsaturated monomers containing sulfonyl groups, such as (meth)acrylamide methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, (meth)allylsulfonic acid, vinylsulfonic acid, styrenesulfonic acid, and 2-sulfoethyl methacrylate, as well as their salts. One or more monomers selected from this group can be used. Preferably, at least one monomer selected from 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and 3-allyloxy-2-hydroxypropanesulfonic acid (HAPS) is preferred, and AMPS and / or HAPS are more preferred. Therefore, when used in combination with corrosion-resistant organic acid compounds, better corrosion protection and better scale prevention can be obtained.

[0052] Other monomers mentioned above include N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylformamide, N-vinyl-methylacetamide, N-vinyloxazolidinone, and other N-vinyl monomers; nitrogen-containing nonionic unsaturated monomers such as (meth)acrylamide, tert-butylacrylamide, N,N-dimethylacrylamide, and N-isopropylacrylamide; hydroxyl-containing unsaturated monomers such as 3-(meth)allyloxy-1,2-dihydroxypropane, (meth)allyl alcohol, and isoprene alcohol; polyoxyethylene unsaturated monomers such as compounds formed by adding approximately 1 to 200 moles of ethylene oxide to (meth)allyl alcohol; (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hydroxyethyl (meth)acrylate; unsaturated carboxylic acid monomers such as dicarboxylic acid and itaconic acid; and aromatic unsaturated monomers such as styrene. One or more monomers selected from these groups may be used.

[0053] <Preferred (meth)acrylic polymers>

[0054] The aforementioned (meth)acrylic acid polymers are more preferably (meth)acrylic acid polymers containing sulfonate groups in their molecules, more preferably (meth)acrylic acid polymers containing sulfonic acid groups in their molecules, and even more preferably copolymers of (meth)acrylic acid monomers and sulfonic acid monomers. The sulfonic acid monomer is preferably an unsaturated monomer containing sulfonic acid groups. As a more preferred specific example, homopolymers or copolymers formed by polymerization or copolymerization of one or more monomers selected from the group consisting of (meth)acrylic acid (preferably acrylic acid (AA)); 2-hydroxy-3-(allyloxy)-1-propanesulfonic acid (HAPS); and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) are also included.

[0055] <Example of manufacturing (meth)acrylic acid copolymers>

[0056] The aforementioned (meth)acrylic acid copolymers can be manufactured using known manufacturing methods. Preferred copolymers are polymers prepared by copolymerizing (i) (meth)acrylic acid monomers with (ii) sulfonic acid monomers selected from monomers having amide and sulfonyl groups, monomers having hydroxyl and sulfonyl groups, etc., in a prescribed mass ratio. It should be noted that any monomer can be used without impairing the effects of the present invention.

[0057] A more preferred (meth)acrylic acid copolymer is a polymer formed by copolymerizing (i) an acrylic acid monomer with (ii) at least one sulfonic acid monomer selected from 2-acrylamide-2-methylpropanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid in a specified mass ratio.

[0058] More preferably, the (meth)acrylic acid copolymer is one or more selected from the group consisting of copolymers of acrylic acid (AA) monomer and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) monomer, copolymers of acrylic acid (AA) monomer and 3-allyloxy-2-hydroxypropanesulfonic acid (HAPS) monomer, etc. A preferred molar ratio of (meth)acrylic acid monomer to sulfonic acid monomer is, for example, 1 to 99:99 to 1, and this molar ratio may appropriately be adopted as <the aforementioned molar ratio (mol%) in the aforementioned (meth)acrylic acid copolymers> described later.

[0059] <Molar ratio (mol%) of the aforementioned (meth)acrylic acid monomer to the aforementioned sulfonic acid monomer>

[0060] The molar ratio (mol%:total 100) of the (meth)acrylic acid monomer to the sulfonic acid monomer in the aforementioned copolymer of (meth)acrylic acid monomer and sulfonic acid monomer is not particularly limited. As a preferred lower limit value for the (meth)acrylic acid monomer, it is preferably 50 or more, more preferably 60 or more, more preferably 70 or more, more preferably 75 or more, and more preferably 80 or more. Furthermore, as a preferred upper limit value for the (meth)acrylic acid monomer, it is preferably 99 or less, more preferably 98 or less, further preferably 97 or less, more preferably 95 or less, and even more preferably 90 or less. As a more preferred numerical range for the molar ratio of acrylic acid monomer to sulfonic acid monomer, acrylic acid monomer:sulfonic acid monomer is more preferably 75:25 to 93:7, and more preferably 80:20 to 90:10. By using this molar ratio in the aforementioned copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, better corrosion resistance and better scale prevention can be achieved. It should be noted that this molar ratio can be appropriately adopted as the molar ratio (%) of (meth)acrylic acid monomer and sulfonic acid monomer used to form copolymers such as AA / AMPS polymers and AA / HAPS polymers described later.

[0061] As a more preferred molar ratio in the aforementioned (meth)acrylic acid copolymer, the molar ratio (mol%) of the (meth)acrylic acid monomer to the sulfonic acid monomer containing amide and / or hydroxyl groups in the copolymer is more preferably 75:25 to 93:7, and even more preferably 80:20 to 90:10. By setting this molar ratio, a better anti-corrosion effect can be achieved. It should be noted that this molar ratio can appropriately adopt the preferred lower limit and preferred upper limit values ​​of the aforementioned <molar ratio in the aforementioned (meth)acrylic acid monomer and sulfonic acid monomer copolymer>.

[0062] Furthermore, as a more preferred molar ratio in the aforementioned (meth)acrylic acid copolymers, in the case of AA / AMPS-based polymers and AA / HAPS-based polymers, the AA / AMPS ratio and AA / HAPS ratio (molar percentage) (AA:AMPS or HAPS) are more preferably 75:25 to 93:7, and even more preferably 80:20 to 90:10. By setting this molar ratio, a better anti-corrosion effect can be achieved. It should be noted that this molar ratio can appropriately adopt the preferred lower limit and preferred upper limit values ​​of the aforementioned <molar ratio in the aforementioned (meth)acrylic acid monomer and sulfonic acid monomer copolymer>.

[0063] <weight-average molecular weight of (meth)acrylic acid copolymers>

[0064] The weight-average molecular weight of the copolymer of (meth)acrylic acid monomer and sulfonic acid monomer obtained by GPC method is not particularly limited. As a preferred lower limit, it is preferably 500 or more, more preferably 1000 or more, further preferably 2000 or more, more preferably 3000 or more, and even more preferably 4000 or more. As a preferred upper limit, it is preferably 100,000 or less, more preferably 50,000 or less, further preferably 40,000 or less, more preferably 30,000 or less, and even more preferably 20,000 or less. As a preferred numerical range for (meth)acrylic acid monomer and sulfonic acid monomer, it is more preferably 3000 to 30000, and more preferably 4000 to 20000. Furthermore, the preferred weight-average molecular weight of AA / AMPS-based polymers and AA / HAPS-based polymers can appropriately adopt the above-mentioned preferred lower and upper limits. As a preferred numerical range, it is preferably 3000 to 30000, and more preferably 4000 to 20000. By adjusting to this weight-average molecular weight, better corrosion resistance and scale prevention can be achieved.

[0065] The weight-average molecular weights of the polymers in this specification can be obtained using standard substances by gel permeation chromatography (GPC analysis). It should be noted that when sodium polyacrylate is used as a standard substance, the value can be expressed as a conversion from sodium polyacrylate.

[0066] 1-2-2. Dicarboxylic acid polymers

[0067] The polymer used in this embodiment is preferably a dicarboxylic acid polymer, more preferably a maleic acid polymer, and more specifically, preferably a polymer of maleic acid monomer, a copolymer of maleic acid monomer with other monomers (e.g., aromatic unsaturated monomers, unsaturated hydrocarbon monomers, etc.), and even more preferably a polymer of maleic acid monomer, or a copolymer of maleic acid monomer with unsaturated hydrocarbon monomers (preferably isobutylene monomer). Therefore, when used in combination with corrosion-resistant organic acid compounds, better corrosion protection and scale prevention can be achieved.

[0068] <Dicarboxylic acid polymers and their manufacturing examples>

[0069] The aforementioned dicarboxylic acid polymers (homopolymers or copolymers) can be manufactured using known methods. Preferred copolymers are polymers formed by polymerizing (i) maleic acid monomers with (ii) monomers containing unsaturated bonds selected from aromatic unsaturated monomers such as styrene, unsaturated hydrocarbon monomers such as isobutylene, etc., in a prescribed mass ratio. It should be noted that any monomer can be used without impairing the effects of the present invention.

[0070] Examples of dicarboxylic acid polymers include polymers (homopolymers, copolymers) formed by polymerizing one or more dicarboxylic acid monomers, such as maleic acid (anhydride), epoxy succinic acid, and itaconic acid, in an aqueous solution. In addition to dicarboxylic acid monomers, monomers with unsaturated bonds may also be included in the aqueous solution, and polymers (copolymers) formed by polymerizing carboxylic acid monomers and other monomers with unsaturated bonds may use one or more of these monomers.

[0071] The dicarboxylic acid monomers mentioned above are not particularly limited, and examples include organic acid monomers such as maleic acid monomers, epoxysuccinic acid monomers, itaconic acid monomers, and their ester monomers. Furthermore, unsaturated organic acid monomers and their esters are preferred. One or more of these monomers may be used.

[0072] Monomers containing unsaturated bonds other than the aforementioned dicarboxylic acid monomers are not particularly limited, and examples include, for instance, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylformamide, N-vinyl-methylacetamide, N-vinyloxazolidinone, and other N-vinyl monomers; nitrogen-containing nonionic unsaturated monomers such as (meth)acrylamide, tert-butylacrylamide, N,N-dimethylacrylamide, and N-isopropylacrylamide; and 3-(meth)allyloxy-1,2-dihydroxypropane. Unsaturated monomers containing hydroxyl groups, such as (meth)allyl alcohol and isoprene alcohol; unsaturated monomers containing polyoxyethylene, such as compounds formed by adding approximately 1 to 200 moles of ethylene oxide to (meth)allyl alcohol; (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hydroxyethyl (meth)acrylate; unsaturated carboxylic acid monomers, such as (meth)acrylic acid and itaconic acid; aromatic unsaturated monomers, such as styrene; and unsaturated hydrocarbons, such as isobutylene, may be used, with one or more selected from these monomers.

[0073] The aforementioned dicarboxylic acid polymer is more preferably selected from one or more of maleic acid polymers, epoxy succinic acid polymers (preferably epoxy succinic acid homopolymers), and itaconic acid polymers, and even more preferably maleic acid polymers and / or epoxy succinic acid polymers, and even more preferably maleic acid polymers.

[0074] The weight-average molecular weight of the aforementioned dicarboxylic acid polymers is not particularly limited, but more preferably 250 or 500-10000, more preferably 500-5000, more preferably 500-3000, and even more preferably 500-2000. The weight-average molecular weight of the polymers in this specification can be obtained using standard substances by gel permeation chromatography (GPC analysis). It should be noted that when sodium polyacrylate is used as a standard substance, the value can be expressed as a conversion of sodium polyacrylate.

[0075] 1-2-2-1. Maleic acid polymers

[0076] Among the aforementioned dicarboxylic acid polymers, maleic acid polymers are preferred. These maleic acid polymers are preferably polymers containing maleic acid monomers as structural units, and can be either homopolymers or copolymers. Examples of homopolymers include polymaleic acid polymers containing maleic acid monomers, polymerized using maleic acid monomers. Furthermore, examples of copolymers are not particularly limited, and copolymers of maleic acid monomers and other monomers (unsaturated monomers) capable of copolymerizing with them are also possible. It should be noted that the maleic acid polymer can be a water-soluble salt, and the salt described in the above-mentioned polymers may be appropriately used.

[0077] <Maleic acid monomers>

[0078] The aforementioned maleic acid monomers are not particularly limited, and examples include maleic acid monomers (such as maleic anhydride, maleic acid, maleate salt, etc.) and maleic acid ester monomers, and one or more of them may be used.

[0079] Among the aforementioned maleic acid monomers, maleic acid monomers are preferred. In addition, maleic anhydride monomers include maleic anhydride and maleic anhydride hydrolysate (maleic acid).

[0080] Examples of maleic esters include, for example, alcohols of saturated hydrocarbons such as methanol and ethanol, alcohols of unsaturated hydrocarbons such as allyl alcohol and methyl allyl alcohol, polyalkylene alcohols, polyoxyalkylene monomethyl ethers, polyoxyalkylene monoallyl ethers, and polyalkylene diol derivatives, and one or more of these may be used.

[0081] <Merizates other than maleic acid monomers that can be copolymerized>

[0082] There are no particular limitations on the monomers that can copolymerize with maleic acid monomers, and examples such as compounds described above in the section on "monomers with unsaturated bonds other than dicarboxylic acid monomers" can be appropriately used. Among the aforementioned monomers capable of copolymerizing with maleic acid monomers, unsaturated hydrocarbon monomers (preferably olefinic unsaturated hydrocarbon monomers) are preferred. These unsaturated hydrocarbon monomers can be either chain-like or cyclic. Furthermore, monoolefinic unsaturated hydrocarbon monomers are preferred, and those with 4 to 6 carbon atoms are particularly preferred. Among these copolymerizable monomers, chain-like monoolefinic unsaturated hydrocarbon monomers are preferred, and among these, butene monomers are more preferably preferred, with isobutene monomers being even more preferred. Therefore, when used in combination with corrosion-resistant organic acid compounds, a better corrosion-resistant effect can be obtained.

[0083] Examples of monoalkenes with 4 to 6 carbon atoms among the monomers capable of copolymerizing with maleic acid monomers include chain-like monoalkenes such as butene (isobutene, α-butene (1-butene), cis-β-butene (cis-2-butene), trans-β-butene (trans-2-butene)), 1-pentene, 2-pentene, methylbutene, methylpentene, and hexene; and cyclic monoalkenes such as cyclopentene, methylcyclopentene, and cyclohexene. One or more of these can be used. Therefore, when used in combination with corrosion-resistant organic acid compounds, a better corrosion-resistant effect can be obtained.

[0084] <Preferred Maleic Acid-Based Polymers>

[0085] Preferred maleic acid polymers are copolymers of maleic acid monomers and monoolefinic unsaturated hydrocarbon monomers (preferably isobutylene monomers), and / or polymaleic acid (preferably homopolymers of maleic acid monomers). Therefore, when used in combination with corrosion-resistant organic acid compounds, a better corrosion-resistant effect can be obtained.

[0086] <Molar ratio (mol%) of the aforementioned maleic acid monomer to other monomers>

[0087] The molar ratio (mol%: total 100) of maleic acid monomer to other monomers in the aforementioned maleic acid polymer is not particularly limited, but as a preferred lower limit value for maleic acid monomer, it is preferably 50% or more, more preferably 60% or more, and more preferably 70% or more.

[0088] As a more preferred molar ratio in the aforementioned maleic acid copolymer, the molar ratio (mol%: total 100) of maleic acid monomer to monoolefinic unsaturated hydrocarbon (preferably 4 to 6 carbons) monomer is not particularly limited, but as a preferred lower limit value for maleic acid monomer, it is preferably 50 or more, more preferably 60 or more, and more preferably 70 or more.

[0089] <Weight-average molecular weight of maleic acid polymers>

[0090] The weight-average molecular weight of the aforementioned maleic acid-based polymers obtained by GPC is not particularly limited. As a preferred lower limit, it is preferably 250 or more, more preferably 500 or more. Furthermore, as a preferred upper limit, it is preferably 10,000 or less, more preferably 8,000 or less, further preferably 5,000 or less, more preferably 3,000 or less. As a preferred numerical range, it is preferably 500 to 5,000, more preferably 500 to 3,000. Therefore, when used in combination with corrosion-resistant organic acid compounds, better corrosion resistance and better scale prevention can be achieved.

[0091] 1-3. Corrosion-resistant organic acid compounds

[0092] The corrosion-resistant organic acid compound used in this embodiment is not particularly limited, but is preferably an organic acid compound that has a corrosion-resistant effect on metal materials in contact with water.

[0093] The index representing the corrosion-resistant effect of the organic acid compound used in this embodiment (hereinafter also referred to as the "organic acid corrosion-resistant effect index") is preferably 4 or more, more preferably 4.5 or more, and even more preferably 5 or more, from the viewpoint of achieving better corrosion resistance. Furthermore, the upper limit is not particularly limited, but is preferably 20 or less, more preferably 18 or less, even more preferably 15 or less, and even more preferably 14 or less. The preferred numerical range is more preferably 4 to 15. Therefore, when used in combination with a polymer, a better corrosion-resistant effect can be obtained. This organic acid corrosion-resistant effect index can be calculated using the formula for the <organic acid corrosion-resistant effect index> shown in the [Examples] section described later.

[0094] For corrosion-resistant organic acid compounds, it is preferable to determine whether an organic acid corrosion resistance index can exert a corrosion resistance effect by taking into account, for example, the slower the corrosion rate of the test water containing organic acids and polymers or the fact that it falls within a set numerical range.

[0095] More preferably, the method described in Test Example 1 of the [Examples] below and the formula for calculating the corrosion rate (mm / y) can be used to determine whether an organic acid corrosion protection index is effective. The corrosion rate (mm / y) at which an effective corrosion protection effect can be achieved is preferably less than 0.10, more preferably 0.08 or less, further preferably 0.05 or less, and even more preferably 0.03 or less. For example, the organic acid corrosion protection index of a corrosion-resistant organic acid compound with a corrosion rate in the range of 0.03 or less can be set as the index at which an effective corrosion protection effect can be obtained.

[0096] The aforementioned corrosion-resistant organic acid compounds preferably have hydroxyl and / or carboxylic acid groups as functional groups, and more preferably have hydroxyl and carboxylic acid groups as functional groups.

[0097] The number of hydroxyl groups in the aforementioned corrosion-resistant organic acid compound is not particularly limited, and can be any one or more, with 0 or more being the preferred lower limit. This results in a better corrosion-resistant effect when used in combination with a polymer. Similarly, the number of carboxylic acid groups in the aforementioned corrosion-resistant organic acid compound is not particularly limited, and can be any one or more, with 1 or more being the preferred lower limit. This results in 2 or more being the preferred lower limit. This also results in a better corrosion-resistant effect when used in combination with a polymer. It is important that there is at least one carboxylic acid group, but a higher number of hydroxyl and carboxylic acid groups is considered beneficial for achieving the desired effect in this embodiment. The aforementioned corrosion-resistant organic compound contains at least one carboxylic acid group, and the sum of the number of carboxylic acid groups and hydroxyl groups is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more. The upper limit of the number of carboxylic acid groups and / or hydroxyl groups in the molecule of the aforementioned corrosion-resistant organic acid compound is not particularly limited, and is limited according to the molecular weight.

[0098] The molecular weight (MW) of the aforementioned corrosion-resistant organic acid compound is not particularly limited, but as a preferred lower limit, it is preferably 100 or more, more preferably 125 or more, and even more preferably 150 or more. Furthermore, as a preferred upper limit, it is not particularly limited, but is preferably 300 or less, more preferably 290 or less. Therefore, when used in combination with a polymer, a better corrosion-resistant effect can be obtained.

[0099] Examples of the aforementioned corrosion-resistant organic acid compounds include, but are not limited to, citric acid, tartaric acid, viscous acid, glucoheponic acid, butanetetracarboxylic acid, iminodiamalic acid, and 3-hydroxy-2,2'-iminodisuccinic acid. One or more of these compounds can be used. Therefore, when used in combination with a polymer, a better corrosion-resistant effect can be obtained. From the viewpoint of achieving a better corrosion-resistant effect and a better scale-preventing effect through combination with a polymer, iminodiamalic acid is more preferred.

[0100] 1-4. The combined use of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds, the preferred dosage and preferred ratio of each component.

[0101] In this embodiment, in the water system corrosion prevention treatment method for inhibiting corrosion of metals in contact with water, by using the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound, these components are present in the water system, thereby achieving a better metal corrosion prevention effect. Hereinafter, more preferred amounts of each component used in the water system, or the proportions and mixing ratios of the agent, will be described.

[0102] In addition, other embodiments of this invention can also provide techniques to enhance, improve or improve the metal corrosion protection effect of the aforementioned polymer present in the water system by combining the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound in the water system. Hereinafter, a better mass usage ratio or mass content ratio in the agent will be described.

[0103] <Preferred dosage or addition amount of the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound>

[0104] There is no particular limitation on the amount of polymer used or added to the water system (mg solid / L, hereinafter referred to as "mg / L"). As a preferred lower limit, it is preferably 1 mg / L or more, more preferably 2 mg / L or more, more preferably 3 mg or 4 mg / L or more, more preferably 5 mg / L or more, more preferably 6 mg / L or more, more preferably 7 mg / L or more, and more preferably 8 mg / L or more. As for the preferred upper limit, there is no particular limitation. From the viewpoint of reducing environmental impact and cost, it is preferably 100 mg / L or less, more preferably 50 mg / L or less, more preferably 40 mg / L or less, more preferably 30 mg / L or less, and more preferably 20 mg / L or less.

[0105] There is no particular limitation on the amount or amount of (meth)acrylic acid polymer used or added to the water system (mg solid / L, hereinafter referred to as "mg / L"). As a preferred lower limit, it is preferably 1 mg / L or more, more preferably 2 mg / L or more, more preferably 3 mg or 4 mg / L or more, more preferably 5 mg / L or more, more preferably 6 mg / L or more, more preferably 7 mg / L or more, and more preferably 8 mg / L or more. As for the preferred upper limit, there is no particular limitation. From the viewpoint of reducing environmental impact and cost, it is preferably 100 mg / L or less, more preferably 50 mg / L or less, more preferably 40 mg / L or less, more preferably 30 mg / L or less, and more preferably 20 mg / L or less.

[0106] As a further preferred method, the amount or addition (mg solid / L) of the sulfonated (meth)acrylic polymer used in the water system can be appropriately adopted from the preferred lower and upper limits of the aforementioned (meth)acrylic polymer usage, etc., with a more preferred numerical range of 3 to 50 mg / L, and even more preferably 5 to 20 mg / L. Furthermore, as a more preferred method, the amount (mg solid / L) of the aforementioned AA / AMPS polymer and / or the aforementioned AA / HAPS polymer used in the water system can be appropriately adopted from the preferred lower and upper limits of the aforementioned (meth)acrylic polymer usage, with a more preferred numerical range of 3 to 50 mg / L, and even more preferably 5 to 20 mg / L.

[0107] There is no particular limitation on the amount or amount of dicarboxylic acid polymer used or added to the water system (mg solid / L, hereinafter referred to as "mg / L"). As a preferred lower limit, it is preferably 1 mg / L or more, more preferably 2 mg / L or more, more preferably 3 mg or 4 mg / L or more, more preferably 5 mg / L or more, more preferably 6 mg / L or more, more preferably 7 mg / L or more, and more preferably 8 mg / L or more. As for the preferred upper limit, there is no particular limitation. From the viewpoint of reducing environmental impact and cost, it is preferably 100 mg / L or less, more preferably 50 mg / L or less, more preferably 40 mg / L or less, more preferably 30 mg / L or less, and more preferably 20 mg / L or less.

[0108] As a further preferred method, the amount or addition of the aqueous maleic acid polymer (mg solid / L) can be appropriately adopted from the preferred lower and upper limits of the aforementioned amount of maleic acid polymer, etc., with a more preferred numerical range of 3 to 50 mg / L, and even more preferably 5 to 20 mg / L. Furthermore, as a more preferred method, the amount (mg solid / L) of the aqueous MA-based homopolymer and / or MA / IB-based polymer can be appropriately adopted from the preferred lower and upper limits of the aforementioned amount of maleic acid polymer, with a more preferred numerical range of 3 to 50 mg / L, and even more preferably 5 to 20 mg / L.

[0109] In this embodiment, when using polymers from different systems in the water system, for example, when using a combination of sulfonated (meth)acrylic acid polymers and dicarboxylic acid polymers, the usage amounts of the aforementioned polymers can be set as their respective usage amounts. When using multiple such polymers from different systems, the total usage amount or total addition amount of the aforementioned polymers is not particularly limited. As a preferred lower limit, it is preferably 6 mg / L or more, more preferably 8 mg / L or more, further preferably 10 mg / L or more, more preferably 12 mg / L or more, more preferably 14 mg / L or more, and more preferably 16 mg / L or more. As for the preferred upper limit, it is not particularly limited, but from the viewpoint of reducing environmental impact and cost, it is preferably 200 mg / L or less, more preferably 100 mg / L or less, and further preferably 80 mg / L, 60 mg / L, or 40 mg / L or less.

[0110] In this embodiment, when using sulfonated (meth)acrylic acid polymers and dicarboxylic acid polymers in an aqueous system, their usage ratio in the aqueous system or their mixing ratio in the reagent is not particularly limited. The usage amount or addition amount (mg / L) in the aqueous system can be appropriately combined to determine the optimal ratio. The preferred range for this usage ratio or mixing ratio is 3–50:30–3, more preferably 5–20:20–5. Examples of such combinations include, for instance, combinations of the aforementioned AA / AMPS polymers and / or the aforementioned AA / HAPS polymers with MA homopolymers and / or MA / IB polymers, but are not limited to these.

[0111] There is no particular limitation on the amount or amount of the aforementioned anti-corrosion organic acid compound used in the water system (mg solid / L, hereinafter referred to as "mg / L"). As a preferred lower limit, it is preferably 1 mg / L or more, more preferably 2 mg / L or more, further preferably 3 mg or 4 mg / L or more, more preferably 5 mg / L or more, more preferably 6 mg / L or more, more preferably 7 mg / L or more, and more preferably 8 mg / L or more. As for the preferred upper limit, there is no particular limitation. From the viewpoint of reducing environmental impact and cost, it is preferably 100 mg / L or less, more preferably 50 mg / L or less, further preferably 40 mg / L or less, more preferably 30 mg / L or less, and more preferably 20 mg / L or less.

[0112] There is no particular limitation on the amount or amount of iminodiamalic acid used or added in the water system (mg solid / L, hereinafter referred to as "mg / L"). The preferred lower limit and upper limit of the aforementioned amount of anti-corrosion organic acid compound can be appropriately adopted as a more preferred numerical range, more preferably 3 to 50 mg / L, and even more preferably 5 to 20 mg / L.

[0113] When using the aforementioned polymer and the aforementioned anti-corrosion organic acid compound in an aqueous system, their usage ratio in the aqueous system or their mixing ratio in the reagent are not particularly limited. The usage amount or addition amount (mg / L) of each of the aforementioned polymer and the aforementioned anti-corrosion organic acid compound in the aqueous system can be appropriately combined to determine the ratio. The preferred range of this usage ratio or mixing ratio is preferably 3–50:30–3, more preferably 3–20:20–3, and even more preferably 3–10:10–3. Examples of combinations of the aforementioned polymer and the aforementioned anti-corrosion organic acid compound in which such preferred usage ratios or mixing ratios can be applied are not particularly limited. Preferred combinations include combinations of sulfonated (meth)acrylic acid polymers (preferably the aforementioned AA / AMPS polymers and / or the aforementioned AA / HAPS polymers) with anti-corrosion organic acid compounds (preferably iminodiamalic acid); and combinations of maleic acid polymers (preferably MA homopolymers and / or MA / IB polymers) with anti-corrosion organic acid compounds (preferably iminodiamalic acid).

[0114] When using the aforementioned (meth)acrylic acid polymers, dicarboxylic acid polymers, and anti-corrosion organic acid compounds in an aqueous system, their usage ratio in the aqueous system or their mixing ratio in the reagent is not particularly limited. The usage or addition amount (mg / L) of each of the aforementioned (meth)acrylic acid polymers, dicarboxylic acid polymers, and anti-corrosion organic acid compounds in the aqueous system can be appropriately combined to determine the optimal ratio. A preferred range for this usage ratio or mixing ratio is 3–50:3–50:3–50, more preferably 3–20:3–20:3–20, and even more preferably 3–10:3–10:3–10. Examples of combinations in which such preferred usage ratios or mixing ratios can be applied are not particularly limited. A preferred combination includes a (meth)acrylic acid polymer having a sulfonate group (preferably the aforementioned AA / AMPS polymers and / or the aforementioned AA / HAPS polymers): a maleic acid polymer (preferably MA homopolymers and / or MA / IB polymers): an anti-corrosion organic acid compound (preferably iminodiamalic acid).

[0115] <Any ingredient>

[0116] In this embodiment, in addition to the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound, any component may be appropriately used in the water system or included in the agent without impairing the effects of the present invention. There are no particular limitations on this arbitrary component; for example, one or more selected from pH adjusters, defoamers, corrosion inhibitors, anti-scaling agents, bactericides, algaecides, etc., may be used.

[0117] In this embodiment, in addition to the combined use of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds, corrosion inhibitors other than or not used can be further used in the water system. Examples of such corrosion inhibitors include organic acid compounds, (meth)acrylic acid polymers and their salts, dicarboxylic acid polymers and their salts, polyaspartic acid and its salts, polyitacic acid and its salts, amine compounds, and amino acid compounds; one or more of these can be used. It should be noted that, from the viewpoint of reducing environmental impact, in this embodiment, it is preferable not to add phosphorus compounds and / or metal salt compounds (mg solid / L) as reagent components to the water system. For example, it is preferable not to add more than 1 mg / L, more preferably not to add more than 0.5 mg / L, further preferably not to add substantially, for example not to add more than 0.1 or 0.05 mg / L, more preferably not to add more than 0 mg / L (i.e., not to add at all as reagent components). Furthermore, from the viewpoint of reducing environmental impact, it is highly preferable that phosphorus compounds and / or metal salt compounds (non-phosphorus and / or non-metallic) are not contained or undetectable in the water system. It should be noted that phosphorus concentration can be determined using the molybdenum blue (ascorbic acid reduction) method (JIS K 010246.1.1). Metal salt compounds can be determined by IPC analysis.

[0118] In this embodiment, in the water system, in addition to the combined use of the aforementioned polymers and the aforementioned anti-corrosion organic acid compounds, an anti-scaling agent other than or unused thereof may also be present. Examples of such anti-scaling agents include (meth)acrylic acid polymers and their salts, dicarboxylic acid polymers and their salts, polyaspartic acid and its salts, etc., and one or more of these may be used.

[0119] In addition, in this embodiment, in the water system, besides the combined use of the aforementioned polymer and the aforementioned anti-corrosion organic acid compound, a slime control agent other than or unused thereof may also be present. There are no particular limitations on the slime control agent; examples include hypochlorous acid and its salts, chlorine, hypobromic acid and its salts, conjugated halogen compounds (stabilized chlorine, stabilized bromine, etc.), organic bactericides, etc., and one or more selected from these may be used.

[0120] 1-5. Metal corrosion prevention methods in water systems

[0121] As described above, the water-based metal corrosion prevention treatment method of this embodiment can use the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound in combination, preferably with these two or three components present in the water system at the same time. The aforementioned polymer is preferably a sulfonated (meth)acrylic acid polymer, more preferably a combination of a sulfonated (meth)acrylic acid polymer and a dicarboxylic acid polymer.

[0122] Furthermore, this embodiment can also add these components to the water system continuously or intermittently. This embodiment can add these components to the water system at the same time or at different times. The water system may be equipped with one or more dosing devices for adding chemicals (components) to the water system. These dosing devices can add individual components, mixtures of two components and other components, or mixtures of three components to the water system at the same time or at different times, such that two or three components are present in the water system at the same time. In this embodiment, examples of places for mixing these components include water system flow paths (e.g., circulating water paths), chemical storage tanks or chemical mixing tanks (e.g., pits) that may be present in the water system, but are not limited to these. Additionally, the water system may appropriately be equipped with measuring devices capable of measuring the concentration of each chemical agent (component concentration) in the water system, and measuring devices capable of measuring the water quality of the water system. In this embodiment, these measurement results can be sent to a control unit or the like. In addition, the method or its steps and actions of this embodiment can be controlled and managed through the control unit or the like.

[0123] The water system metal corrosion prevention method of this embodiment is as described above, preferably having the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer) and the aforementioned corrosion-resistant organic acid compound, or having the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned corrosion-resistant organic acid compound present in the water system at a predetermined mass usage ratio or mass content ratio.

[0124] In this embodiment, the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer) and the aforementioned corrosion-resistant organic acid compound, or the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned corrosion-resistant organic acid compound can be added to the water system as a single-liquid agent or as a multi-liquid agent.

[0125] As another embodiment of this invention, a method for preventing corrosion of a water system can also be provided by adding a water treatment agent containing at least one of the aforementioned polymers (preferably sulfonated (meth)acrylic acid polymers) or the aforementioned anti-corrosion organic acid compounds to the water system, thereby ensuring that the aforementioned polymers (preferably sulfonated (meth)acrylic acid polymers) and the aforementioned anti-corrosion organic acid compounds are present in the water system.

[0126] In other embodiments of this invention, as a more preferred approach, a water treatment agent containing at least one of the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, or the aforementioned anti-corrosion organic acid compound is added to the water system, thereby enabling the presence of the three components—the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned anti-corrosion organic acid compound—in the water system, which can also provide a water system corrosion protection technology.

[0127] In addition, for water systems, the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer) and the aforementioned anti-corrosion organic acid compound, or the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned anti-corrosion organic acid compound can be used in a manner where these two or three components are present in the water system, and these two or three components can be added at the same time or at different times. The addition of these two or three components can be either continuous or intermittent.

[0128] In this embodiment, as a more preferred approach, a water-based metal corrosion prevention method may also be provided using (i) a metal corrosion inhibitor, (ii) a water treatment agent, or (iii) a water treatment agent or a combination of water treatment agents for metal corrosion prevention. The combination products in this specification may be kit products or reagent kit products.

[0129] (i) A metal corrosion inhibitor comprising the aforementioned polymer (preferably a (meth)acrylic acid polymer having a sulfonate group) and the aforementioned corrosion-resistant organic acid compound. The metal corrosion inhibitor preferably further comprises a dicarboxylic acid polymer.

[0130] (ii) A water treatment agent containing at least the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer) and / or the aforementioned corrosion-resistant organic acid compound, used in water systems for at least combining the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer) and the aforementioned corrosion-resistant organic acid compound to strengthen, enhance or improve metal corrosion protection achieved by the aforementioned polymer.

[0131] (iii) A water treatment agent for metal corrosion prevention, comprising at least one of the aforementioned sulfonated (meth)acrylic acid polymers, the aforementioned dicarboxylic acid polymers, or the aforementioned corrosion-resistant organic acid compounds, for use in water-based metal corrosion prevention, wherein the aforementioned sulfonated (meth)acrylic acid polymers, the aforementioned dicarboxylic acid polymers, and the aforementioned corrosion-resistant organic acid compounds are used in combination for the water system. The water treatment agent may be a combination product consisting of at least one, two, or three of the following: a first water treatment agent comprising the sulfonated (meth)acrylic acid polymer, a second water treatment agent comprising the dicarboxylic acid polymer, and a third water treatment agent comprising the corrosion-resistant organic acid compound. The combination product in this specification may be a kit product or a reagent kit product.

[0132] The water system used in this embodiment is not particularly limited, and examples include cooling water systems, warm water systems, membrane water systems (e.g., reverse osmosis (RO) membrane water systems), pulp process water systems, and washing machine water systems. In this embodiment, the corrosion prevention effect can be fully utilized as long as the water quality of a general water system (preferably a cooling water system) is suitable.

[0133] This embodiment has the excellent characteristic of being applicable to a wide range of water hardness, from high to low. In this embodiment, the anti-corrosion effect can be fully utilized as long as the water quality of a general cooling water system is used.

[0134] Furthermore, in this embodiment, even without using phosphorus compounds as metal corrosion inhibitors, the corrosion-preventing effect can be fully utilized. Therefore, it can be applied to drainage standards for phosphorus concentration in various countries. For example, the phosphorus concentration described in the above-mentioned phosphorus compound addition amount can be appropriately adopted. For example, as a condition for water quality in a water system, the phosphorus concentration can preferably be 0.5 mg / L as P or less, more preferably 0.1 mg / L as P or less.

[0135] Regarding the water quality conditions of the water system, the calcium hardness (mg / L as CaCO3, hereinafter also referred to as "mg / L") is not particularly limited. In this embodiment, not only high hardness but also low hardness can achieve the anti-corrosion effect. As a preferred upper limit value, there is no particular limitation, for example, it is 1000 mg / L or less, preferably 800 mg / L or less, more preferably 700 mg / L or less, and even more preferably 600 mg / L or less. In addition, as a preferred lower limit value, it is preferably 25 mg / L or more, more preferably 50 mg / L or more, further preferably 80 mg / L or more, more preferably 100 mg / L or more, and even more preferably 130 mg / L or 150 mg / L or more. As a preferred numerical range, it is preferably 50 to 1000 mg / L. The method for determining calcium hardness can be based on JIS K0101 Industrial Water Test Method.

[0136] As a condition for water quality in a water system, the alkalinity M (acid consumption (pH 4.8): (mg / L as CaCO3, hereinafter also referred to as "mg / L") is not particularly limited, but is preferably 10 to 1000 mg / L, more preferably 25 to 500 mg / L, and even more preferably 50 to 300 mg / L. The acid consumption (pH 4.8) can be determined according to JIS K0101 Industrial Water Test Method.

[0137] Magnesium hardness is not particularly limited as a condition for water quality in a water system. However, as a preferred upper limit, it is preferably below 500 mg / L, more preferably below 400 mg / L, further preferably below 350 mg / L, and even more preferably below 300 mg / L. The method for determining magnesium hardness can be based on JIS K0101, the test method for industrial water.

[0138] Furthermore, regarding the water quality conditions of the water system, the chloride ion concentration is not particularly limited, but is preferably 800 mg / L or less, more preferably 600 mg / L or less, even more preferably 500 mg / L or less, more preferably 300 mg / L or less, and even more preferably 100 mg / L or less. The chloride ion concentration can be determined according to JIS K0101 Industrial Water Test Method.

[0139] Furthermore, regarding the water quality conditions of the water system, the sulfate ion concentration is not particularly limited, but is preferably below 800 mg / L, more preferably below 600 mg / L, even more preferably below 500 mg / L, more preferably below 300 mg / L, and even more preferably below 100 mg / L. The sulfate ion concentration can be determined according to JIS K0101 Industrial Water Test Method.

[0140] Furthermore, regarding the water quality conditions of the water system, the silica concentration is not particularly limited, but is preferably 5–250 mg / L, more preferably 10–150 mg / L, and even more preferably 15–100 mg / L. The silica concentration can be determined according to JIS K0101 Industrial Water Test Method.

[0141] Regarding the water quality conditions of the water system, the preferred pH is 6-11, more preferably 6.5-10, and even more preferably 7-9. Furthermore, the water temperature of the water system is not particularly limited, but is preferably 0-100°C, more preferably 5-80°C, even more preferably 10-60°C, and even more preferably 10-40°C. Additionally, the lower limit of the water temperature is preferably 0°C or higher, more preferably 5°C or higher. Furthermore, in this embodiment, as described later in the [Examples], it has the following excellent advantages: even in areas where the water system is locally hot, such as heat exchangers, heat exchange devices, and their piping, scale buildup can be suppressed or prevented in these high-temperature areas. In this case, the high-temperature condition that can be well handled is not particularly limited, but the preferred upper limit is, for example, 150°C or lower, preferably 130°C or lower, even more preferably 120°C or lower, more preferably 100°C or lower, even more preferably 80°C or lower, even more preferably 60°C or lower, and even more preferably 40°C or lower.

[0142] As a preferred embodiment, this method is preferably applied to water systems where metal materials that are easily corroded by water are used in various parts (e.g., heat exchangers, piping, etc.).

[0143] Furthermore, as a preferred embodiment, it is expected to prevent scale buildup in heat transfer surfaces (heat exchangers, flow paths for heat exchange, piping, and heat exchange mechanisms including them), which helps maintain the concentration of corrosion inhibitor in the water system containing the heat transfer surfaces. Therefore, it is preferably applied to water systems containing heat transfer surfaces. As a more preferred embodiment, it is more preferably applied to cooling water systems, and even more preferably to circulating cooling water systems. According to this embodiment, the corrosion prevention effect achieved by the corrosion prevention treatment method of this embodiment can be fully utilized.

[0144] The method of this embodiment can also be implemented by a control unit, including a CPU, in a device (such as a computer, PLC, server, cloud service, etc.) used to manage the aforementioned metal corrosion prevention treatment, cooling water system, etc. Alternatively, the method of this embodiment can be stored as a program on hardware resources equipped with a recording medium (non-volatile memory (USB memory, etc.), SSD, HDD, CD, DVD, Blu-ray disc, etc.) and implemented by the aforementioned control unit. This recording medium is preferably a computer-readable recording medium. Devices equipped with this control unit, such as a metal corrosion prevention treatment system that controls the process by adding chemicals to the water system, can also be provided. Furthermore, in this management device, as a component of a computer, at least a CPU is included, and examples include an input unit such as a keyboard, a communication unit such as a network, a display unit such as a monitor, a storage unit such as an HDD, ROM, RAM, etc., from which one or more can be selected. Among these, RAM, storage unit, display unit, and input unit are preferred, and the selected components are connected, for example, via a bus that serves as a data transmission path.

[0145] Cooling Water System

[0146] The cooling water system used in this embodiment is not particularly limited, but is preferably a system that circulates cooling water for the operation of heat exchangers in air conditioning equipment in buildings, district facilities, and factories. Furthermore, the aforementioned cooling water system can be any of a single-pass type, an open-loop type, or a closed-loop type.

[0147] In this embodiment, by applying it to a circulating cooling water system, it can achieve excellent corrosion prevention in the circulating cooling water system.

[0148] There are no particular limitations on the circulating cooling water system. For example, a water system equipped with a cooling tower within the system is preferred, such as one installed in air conditioning, petrochemical complexes, or general plants. This circulating cooling water system is preferably configured to indirectly cool heat sources generated in these air conditioning units, general plants, etc., but it can also be a general water system that includes a heat exchanger, circulating water circuit, and cooling tower.

[0149] The type of circulating cooling water system is not particularly limited; it can be either an open circulating cooling water system or a closed circulating cooling water system. An open circulating cooling water system preferably has a configuration in which the cooling water can circulate in an open manner, while a closed circulating cooling water system preferably has a configuration in which the cooling water can circulate in a closed manner.

[0150] Furthermore, the metal corrosion prevention treatment method for the cooling water system in this embodiment (more specifically, the metal corrosion prevention treatment method for metal components within the cooling water system) preferably includes at least the steps of adding the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound to the cooling water system and bringing them into contact with the aforementioned metal components. It should be noted that, at this time, (i) the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound, or (ii) the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned corrosion-resistant organic acid compound can be added as a single-liquid metal corrosion prevention agent, or as a multi-liquid metal corrosion prevention agent using a combination product. It should be noted that, for the cooling water system, one or more of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds can be added at the same time or at different times, preferably in a manner where these two or more components coexist in the water system. The duration for which these two or more components coexist in the water system is not particularly limited and can be either continuous or intermittent.

[0151] Furthermore, the location for adding the chemical is not particularly limited and can be any location within the cooling water system. Examples include sprinkler units, recesses, makeup water supply units, chemical injection units, circulating water paths, transfer pumps, and heat exchangers. Preferably, it can be added to a makeup water supply unit, chemical injection unit, circulating water path, or transfer pump, and can be added to one or more of these locations. Adding these two or more components in a manner that allows them to exist in any location within the water system provides a better corrosion protection effect for metal materials in contact with water downstream. Additionally, when all or part of the water system is circulating, mixing these two or more components through water circulation can further enhance the corrosion protection effect for metal materials in contact with water.

[0152] Thus, the metal corrosion prevention treatment method according to this embodiment can impart excellent corrosion prevention effect to metal components that come into contact with water.

[0153] Reference Figure 1 The metal corrosion prevention treatment method for an open circulating cooling water system 1, as an example of this embodiment, will be described, but this embodiment is not limited to this. Hereinafter, the metal corrosion prevention treatment using the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound will be described. As preferred embodiments of these components, as described above, examples such as the aforementioned sulfonated (meth)acrylic acid polymer, the aforementioned dicarboxylic acid polymer, and the aforementioned corrosion-resistant organic acid compound can be cited.

[0154] In the open circulating cooling water system 1, water containing one or more of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds is transported from the groove 15 to the heat exchanger 30 via the circulation water path 20 using a transfer pump 21, and then returns to the open cooling tower 10 via the circulation water path 20 after passing through the heat exchanger 30. Within the cooling tower 10, the water containing the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds accumulates in the groove 15 after passing through the spray unit 12 and the filling material area 13, and is again transported to the circulation water path 20 using the pump 21. According to this embodiment, the corrosion-resistant effect of the cooling water system can be continuously maintained during this circulation. Through this circulation, the aforementioned polymers and the aforementioned corrosion-resistant organic acid compounds present in the water system can come into contact with metal components, thereby providing a corrosion-resistant effect to the metal components. It should be noted that it is preferable to add one or more of the aforementioned polymers and the aforementioned anti-corrosion organic acid compounds to the water system using a dosing device capable of adding either or a mixture of two or more of these components, so that the two or more components coexist in the water system. Alternatively, the amount of each component can be adjusted so that each component reaches a specified concentration range in the water system.

[0155] One or more of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compound can be delivered to the recess 15 at the same time or at different times using one or more agent injection units 17. During delivery, the two are mixed in the piping or within the recess 15. Furthermore, one or more agent injection units 17 can be provided; for example, multiple different agent injection units can be provided for using one or more of the aforementioned polymers and the aforementioned corrosion-resistant organic acid compound, or a single agent injection unit can be provided for adding a liquid agent containing them to the water system or mixing these components. Water insufficient due to evaporation, etc., is supplied to the recess 15 as needed via a makeup water supply unit 16. The flow path for supplying makeup water to the recess 15 can also be configured to allow the addition of one or more agents originating from the agent injection unit 17. It should be noted that cooling air is discharged from 11 via vents 18 through 13 and 12, using external gas exhaust from the air supply unit 11.

[0156] It should be noted that in the description of the examples of water-based metal corrosion prevention treatment methods in the above embodiments, descriptions of the aforementioned polymers (e.g., the aforementioned sulfonated (meth)acrylic acid polymers, the aforementioned dicarboxylic acid polymers), the aforementioned corrosion-resistant organic acid compounds, their usage concentrations, usage ratios, and various technical features, components, definitions, terms, treatment methods, and units of water-based metal corrosion prevention treatment, water-based metal corrosion prevention treatment management, water-based metal corrosion prevention systems, and water-based metal corrosion prevention treatment methods, etc., which are the same as or repeated in the following descriptions (e.g., "2." to "3."), are appropriately omitted. However, the descriptions of "1." to "3." are also applicable to any of the embodiments and can be appropriately adopted in each embodiment.

[0157] 2. Metal corrosion inhibitors, etc., in this embodiment

[0158] In the description of examples of metal corrosion inhibitors, water treatment agents, and combination products for water treatment agents in this embodiment, descriptions of the aforementioned polymers (e.g., the aforementioned sulfonated (meth)acrylic acid polymers, the aforementioned dicarboxylic acid polymers), the aforementioned corrosion-resistant organic acid compounds, their usage concentrations, usage ratios, and descriptions of various technical features, components, definitions, terms, treatment methods, and various units, such as water-based metal corrosion prevention treatment, water-based metal corrosion prevention treatment management, water-based metal corrosion prevention systems, and water-based metal corrosion prevention treatment methods, which are the same as or repeated in the above content (e.g., "1.") and the following content (e.g., "3."), are appropriately omitted. However, the descriptions of "1." to "3." are also applicable to any of the embodiments and can be appropriately adopted in each embodiment.

[0159] This embodiment, by using the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer and / or the aforementioned dicarboxylic acid polymer) and the aforementioned corrosion-resistant organic acid compound in an aqueous system, can achieve excellent corrosion protection against metals in contact with water. That is, the combination of the aforementioned polymer and the aforementioned corrosion-resistant organic acid compound can be contained in or used as an active ingredient in compositions for corrosion protection in aqueous systems, metal corrosion inhibitors for aqueous systems, water treatment agents, chemicals, etc. It should be noted that in this embodiment, the composition can be an agent, and the agent can be a composition.

[0160] In this embodiment, the aforementioned polymers (preferably the aforementioned sulfonated (meth)acrylic acid polymers and / or the aforementioned dicarboxylic acid polymers) and the aforementioned corrosion-resistant organic acid compounds, or mixtures thereof, can be used to manufacture compositions, the aforementioned water-based metal corrosion inhibitors, water treatment agent combination products, etc.

[0161] In addition, this embodiment can also provide the aforementioned polymers (preferably the aforementioned sulfonated (meth)acrylic acid polymers and / or the aforementioned dicarboxylic acid polymers) and the aforementioned corrosion-resistant organic acid compounds, or mixtures thereof, or their use, for use in metal corrosion protection of the aforementioned water systems or for use in applications.

[0162] In addition, this embodiment can also provide a water-based metal corrosion prevention method and a water-based metal corrosion prevention treatment method using the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer and / or the aforementioned dicarboxylic acid polymer) and the aforementioned corrosion-resistant organic acid compound, or the mixture thereof, or a water-based metal corrosion inhibitor, water treatment agent, water treatment agent combination product, etc.

[0163] In addition, this embodiment can provide a metal corrosion inhibitor comprising the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer and / or the aforementioned dicarboxylic acid polymer) and the aforementioned corrosion-resistant organic acid compound.

[0164] Furthermore, this embodiment can also provide a water treatment agent for metal corrosion prevention, which contains at least one of the aforementioned polymers (preferably the aforementioned sulfonated (meth)acrylic acid polymers and / or the aforementioned dicarboxylic acid polymers) or the aforementioned corrosion-resistant organic acid compounds. When used for metal corrosion prevention in a water system, the aforementioned polymers (preferably the aforementioned sulfonated (meth)acrylic acid polymers and / or the aforementioned dicarboxylic acid polymers) and the aforementioned corrosion-resistant organic acid compounds are used in combination for the water system. This water treatment agent can be a combination product of at least one, two, or three of the following: a first water treatment agent containing the aforementioned sulfonated (meth)acrylic acid polymer, a second water treatment agent containing the aforementioned dicarboxylic acid polymer, and a third water treatment agent containing the aforementioned corrosion-resistant organic acid compound.

[0165] As another embodiment of this invention, a water treatment agent can also be provided, which contains the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer) and / or the aforementioned dicarboxylic acid polymer, and / or the aforementioned corrosion-resistant organic acid compound. When used in a water system, the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer and / or the aforementioned dicarboxylic acid polymer) and the aforementioned corrosion-resistant organic acid compound are used in combination to strengthen, improve or enhance the metal corrosion protection achieved by the aforementioned polymer.

[0166] In addition, as another embodiment, it is also possible to provide the aforementioned polymer (preferably the aforementioned sulfonated (meth)acrylic acid polymer and / or the aforementioned dicarboxylic acid polymer), and the aforementioned anti-corrosion organic acid compound, or one or more of them, for use in the manufacture of the aforementioned agents, etc., or for manufacturing purposes or for use.

[0167] In addition, as another aspect of this embodiment, a corrosion prevention method for water systems that uses the aforementioned agents or the like to suppress corrosion of metals in contact with water can also be provided.

[0168] The aforementioned polymers are preferably water-soluble organic polymers, more preferably the aforementioned sulfonated (meth)acrylic acid polymers and / or the aforementioned dicarboxylic acid polymers. Among the aforementioned sulfonated (meth)acrylic acid polymers, copolymers of (meth)acrylic acid monomers and sulfonated monomers are more preferably copolymers of (meth)acrylic acid monomers and monomers containing amide or hydroxyl groups and containing sulfonates. Among the aforementioned dicarboxylic acid polymers, maleic acid polymers are more preferably maleic acid and maleic acid copolymers are more preferably polymaleic acid and maleic acid copolymers.

[0169] The aforementioned (meth)acrylic acid polymers are preferably (meth)acrylic acid polymers containing sulfonyl groups, and the molar ratio of (meth)acrylic acid monomers to sulfonic acid monomers in the polymer is preferably 75:25 to 93:7. Among the aforementioned (meth)acrylic acid polymers, AA / AMPS-based polymers and / or AA / HAPS-based polymers are preferred.

[0170] The aforementioned dicarboxylic acid polymer is preferably a maleic acid polymer, and the molar ratio of maleic acid monomer to other monomers with unsaturated bonds is preferably 50 or more and less than 50. The aforementioned maleic acid polymer is a polymaleic acid and / or MA / butene (preferably IB) polymer.

[0171] The aforementioned corrosion-resistant organic acid compound is preferably selected from one or more of citric acid, tartaric acid, viscous acid, glucoheponic acid, butanetetracarboxylic acid, iminodiamalic acid, and 3-hydroxy-2,2'-iminodisuccinic acid, with iminodiamalic acid being the most preferred.

[0172] The preferred ratio of the aforementioned polymer (preferably a sulfonated (meth)acrylic acid polymer and / or a dicarboxylic acid polymer) and the aforementioned corrosion-resistant organic acid compound in the aqueous system or in the formulation is 3-50:3-50. Furthermore, the preferred ratio of the sulfonated (meth)acrylic acid polymer and the dicarboxylic acid polymer in the aqueous system or in the formulation is 3-50:3-50. Additionally, the preferred ratio of the aforementioned (meth)acrylic acid polymer:the aforementioned dicarboxylic acid polymer:the aforementioned corrosion-resistant organic acid compound in the aqueous system or in the formulation is 3-50:3-50:3-50.

[0173] 3. This technology may also adopt the following technical features, configurations or other solutions.

[0174] [1] A method for preventing corrosion of metals in a water system, which uses: a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid compound with an organic acid corrosion prevention effect index of 4 or higher.

[0175] ·[2] The water system method described in [1] above also uses dicarboxylic acid polymers.

[0176] [3] A water-based metal corrosion prevention treatment method, which uses: a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, a dicarboxylic acid polymer, and an organic acid compound with an organic acid corrosion prevention effect index of 4 or higher.

[0177] ·[4] The method according to any one of [1] to [3] above is a water system corrosion prevention method for inhibiting corrosion of metals in contact with water systems.

[0178] [5] A water-based metal corrosion inhibitor, comprising: a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid compound with an organic acid corrosion inhibitory effect index of 4 or higher.

[0179] [6] A water-based metal corrosion inhibitor containing: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, and (C) an organic acid compound with an organic acid corrosion inhibitory effect index of 4 or higher.

[0180] [7] A water treatment agent containing at least one of the following: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, or (C) an organic acid corrosion protection index of 4 or above, which is used for corrosion protection treatment of metals in water systems in the form of (i) a combination of (A) and (C) above, or (ii) a combination of (B) and (C) above, or (iii) a combination of (A) to (C) above.

[0181] [8] A water treatment agent for improving metal corrosion protection in water systems contains an organic acid compound with an organic acid corrosion protection effect index of 4 or higher. The metal corrosion protection in water systems is improved by using (i) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, or (ii) a dicarboxylic acid polymer, or (iii) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer and a dicarboxylic acid polymer.

[0182] [9] A method for improving the corrosion protection of metals in water systems, wherein an organic acid corrosion protection effect index of 4 or higher is used, and the corrosion protection of metals in water systems is improved by using a copolymer of (A) (meth)acrylic acid monomer and sulfonic acid monomer, or by using a (B) dicarboxylic acid polymer, or by using a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer and (B) dicarboxylic acid polymer.

[0183] ·

[10] is a component selected from one or a combination of two or three of the following: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, (C) an organic acid corrosion inhibitory effect index of 4 or above, or one or more of these components in the manufacture of the agent described in any one of [5] to [8] above, or used in the manufacture of the agent or for the purpose of manufacture.

[0184]

[11] A component selected from one or a combination of two or three of the following: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, (C) an organic acid corrosion protection index of 4 or above, or one or more of these components, in the application of metal corrosion protection treatment in water systems or in the use of metal corrosion protection treatment in water systems.

[0185]

[12] A method for preventing metal corrosion in a water system, wherein a component selected from one or a combination of two or three of the following: (A) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) a dicarboxylic acid polymer, and (C) an organic acid corrosion prevention effect index of 4 or above is used in or added to a water system.

[0186]

[13] A method for strengthening, improving or enhancing the corrosion protection of metals in a water system, wherein an organic acid corrosion protection effect index of 4 or higher is used, and the corrosion protection of metals in a water system is strengthened, improved or enhanced by (i) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, or by (ii) a dicarboxylic acid polymer, or by (iii) a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer and a dicarboxylic acid polymer.

[0187]

[14] An organic acid compound or its application thereof that has an organic acid corrosion resistance index of 4 or higher, used to strengthen, improve or enhance the corrosion protection of metals in water systems by using (i) copolymers of (i) meth)acrylic acid monomers and sulfonic acid monomers, or (ii) dicarboxylic acid polymers, or (iii) copolymers of (i) meth)acrylic acid monomers and sulfonic acid monomers and dicarboxylic acid polymers.

[0188]

[15] The copolymer of the (meth)acrylic acid monomer (preferably an acrylic acid monomer) and the sulfonic acid monomer described in any one of [1] to

[14] is preferably a (meth)acrylic acid monomer and a monoolefin unsaturated sulfonic acid monomer, or the aforementioned sulfonic acid monomer is preferably a monomer having an amide group and a sulfonyl group and / or a monomer having a hydroxyl group and a sulfonyl group. The copolymer of the (meth)acrylic acid monomer and the sulfonic acid monomer is further preferably one or more selected from the group consisting of AA / AMPS polymers and AA / HAPS polymers.

[0189]

[16] The dicarboxylic acid polymer described in any one of [1] to

[15] above is preferably one or more selected from the group consisting of maleic acid polymers and polyepoxysuccinic acid. The maleic acid polymer is further preferably one or more selected from the group consisting of homopolymers of maleic acid monomers (polymaleic acid) and copolymers of maleic acid monomers and unsaturated hydrocarbon monomers (preferably isobutylene monomers). The dicarboxylic acid polymer is even more preferably one or more selected from the group consisting of MA polymers (polymaleic acid) and MA / butene (preferably IB) polymers.

[0190]

[17] The corrosion-resistant organic acid compound described in any one of [1] to

[16] above is preferably an organic acid compound having a carboxylic acid group. More preferably, the corrosion-resistant organic acid compound is an organic acid compound having a carboxylic acid group and a hydroxyl group. The corrosion-resistant organic acid compound is one or more selected from the group consisting of citric acid, tartaric acid, viscous acid, glucoheponic acid, butanetetracarboxylic acid, iminodiamalic acid, and 3-hydroxy-2,2'-iminodisuccinic acid, wherein iminodiamalic acid is more preferably selected.

[0191] ·

[18] The amount of the copolymer of the aforementioned (meth)acrylic acid monomer and sulfonic acid monomer mentioned in [1] to

[17] added to the water system is preferably 5 mg / L or more, and / or the amount of the aforementioned dicarboxylic acid polymer added to the water system is preferably 5 mg / L or more, and / or the amount of the aforementioned anti-corrosion organic acid compound added to the water system is preferably 5 mg / L or more.

[0192] ·

[19] The preferred ratio or mixing ratio of the copolymer of the aforementioned (meth)acrylic acid monomer and sulfonic acid monomer in [1] to

[18] to the aforementioned corrosion-resistant organic acid compound is 5 to 50: 5 to 50.

[0193]

[20] The preferred ratio or mixing ratio of the copolymer of the aforementioned (meth)acrylic acid monomer and sulfonic acid monomer, the aforementioned dicarboxylic acid polymer and the aforementioned anti-corrosion organic acid compound in [1] to

[19] is 5 to 50: 5 to 50: 5 to 50.

[0194] Example

[0195] The following embodiments and comparative examples illustrate the implementation of the present invention. It should be noted that the embodiments described below represent only one example of a representative embodiment of the present invention, and the scope of the present invention should not be narrowly interpreted therein.

[0196] <Raw materials>

[0197] The polymers shown in Tables 1 and 2 were used in the experiment.

[0198] [Table 1]

[0199] Table 1 (Meth)Acrylic Polymers

[0200]

[0201] [Table 2]

[0202] Table 2 Dicarboxylic acid polymers

[0203]

[0204] <Experimental Example 1>

[0205] <Method>

[0206] To investigate organic acids exhibiting good corrosion resistance, corrosion tests were conducted. Operating conditions were: water temperature 30°C, test period 3 days, and rotation speed 150 rpm. Specifically, referring to "K0100: Industrial Corrosion Test Methods," test water adjusted to the following conditions was added to a beaker with a stirrer at the bottom. A long, suspended test strip was then completely immersed in the test water, positioned near the center of the beaker without contacting the stirrer, and the corrosion test was performed.

[0207] The water quality conditions were adjusted to: calcium hardness 500 mg / L as CaCO3, acid consumption (pH 4.8) 200 mg / L as CaCO3, magnesium hardness 250 mg / L, chloride ion concentration 350 mg / L, sulfate ion concentration 500 mg / L, acrylic acid polymer 1 (AA polymer containing sulfur) 10 mg / L, dicarboxylic acid polymer 1 (MA polymer 1) 5 mg / L, organic acid 50 mg / L, and pH 8.6. The organic acids used were those listed in Table 3 below.

[0208] The material used in the experiment was a SPCC test piece (30mm wide × 50mm long × 1mm thick). One test piece was immersed in 1L of test water. The test results were evaluated as follows: the corrosion reduction was calculated from the weight difference of the test piece before and after the test, based on the following formula (where the specific gravity is 7.87g / cm³). 3Calculate the corrosion rate (mm / y). It should be noted that SPCC (Steel Plate Cold Commercial: a type of cold-rolled steel plate) is made of low-carbon steel with a carbon content of less than 0.15%.

[0209] Formula 1

[0210]

[0211] Furthermore, the <Organic Acid Corrosion Resistance Index> is determined using the following formula as an indicator of the corrosion resistance effect of organic acids. The molecular weight (MW) of an organic acid is calculated by the sum of the atomic weights contained in its molecule.

[0212] Organic acid corrosion resistance index = (total oxygen atomic mass in the molecule / molecular weight) × (number of COOH groups in the molecule) × (sum of the number of COOH groups and OH groups in the molecule)

[0213] <Results>

[0214] When the corrosion protection index of an organic acid is less than 4, the corrosion rate is high; when it is above 4, the corrosion rate is low. Therefore, molecules with a corrosion protection index higher than 4 are considered good corrosion inhibitors. Organic acids with a corrosion protection index of 4 or higher are selected as corrosion-resistant organic acid compounds. Among the organic acids used in Experimental Example 1, those with a corrosion protection index of 4 or higher, including glucohepatic acid, tartaric acid, citric acid, viscous acid, 1,2,3,4-butanetetracarboxylic acid, and iminodiamalic acid, were found to have excellent corrosion protection effects with corrosion rates below 0.05. Furthermore, the corrosion rates of these organic acid compounds with a corrosion protection index of 4 or higher are 0.01 to 0.02, which is very good. Therefore, it is preferable to use one or more of these compounds as corrosion-resistant organic acid compounds.

[0215] Furthermore, the corrosion-resistant organic acid compound has a maximum corrosion resistance index of 14, but there is no particular upper limit to the corrosion resistance index, and it can suppress the corrosion rate to below 0.02. Additionally, the inventors believe that organic acids containing hydroxyl (OH) and carboxylic acid (COOH) groups exhibit good corrosion resistance. It is also known that corrosion-resistant organic acid compounds preferably contain hydroxyl (OH) and carboxylic acid (COOH) groups.

[0216] [Table 3]

[0217] Table 3 Anti-aging effects of organic acids

[0218]

[0219] <Experimental Example 2>

[0220] <Method>

[0221] In Experiment 1, iminodiamalic acid, which showed good corrosion resistance, was used. The combination of iminodiamalic acid with (meth)acrylic acid polymers and dicarboxylic acid polymers was investigated. Operating conditions were: water temperature 40°C, test period 3 days, and rotation speed 150 rpm. The water quality conditions for the test were adjusted as follows: calcium hardness 150 mg / L as CaCO3, acid consumption (pH 4.8) 65 mg / L as CaCO3, magnesium hardness 50 mg / L as CaCO3, chloride ion concentration 75 mg / L, sulfate ion concentration 75 mg / L, and pH 7.9.

[0222] The material used in the experiment was the same SPCC test piece (30mm × 50mm × 1mm) as in Test Example 1 above. One test piece was immersed in 1L of test water, and the same corrosion test as in Test Example 1 was conducted. The evaluation of the test results was as follows: the corrosion loss was calculated from the weight difference of the test piece before and after the test, based on the formula used to calculate the corrosion rate (mm / y) in <Test Example 1> (where the specific gravity is 7.87 g / cm³). 3 ), calculate the corrosion rate (mm / y).

[0223] <Results>

[0224] When AA-based polymer 1, MA-based polymer 1, and iminodiamalic acid are used alone, a good anti-corrosion effect is not obtained (Comparative Example 2). In contrast, when AA-based polymer 1 and iminodiamalic acid are used in combination, an improvement in the anti-corrosion effect is observed (Example 1). Furthermore, the anti-corrosion effect is best when the three agents are combined with MA-based polymer 1 (Example 2). The results suggest that a better anti-corrosion effect can be achieved by combining a sulfonated (meth)acrylic polymer (preferably a sulfonated acrylic polymer) with an anti-corrosion organic acid compound, or by combining a dicarboxylic acid polymer with an anti-corrosion organic acid compound. Furthermore, it is believed that a very good anti-corrosion effect can be achieved by combining these three components, a sulfonated (meth)acrylic polymer, a dicarboxylic acid polymer, and an anti-corrosion organic acid compound.

[0225] [Table 4]

[0226] Table 4 Evaluation of the anti-corrosion effect when combined

[0227]

[0228] <Experimental Example 3>

[0229] <Method>

[0230] The corrosion protection effect of the combination of (meth)acrylic acid polymer, dicarboxylic acid polymer, and organic acid was evaluated under water quality conditions different from those in Test Example 2. In Test Example 3, the same corrosion test as in Test Example 1 was conducted.

[0231] The operating conditions were: water temperature 30℃, test period 3 days, and rotation speed 150 rpm. Water quality conditions were adjusted to: calcium hardness 530 mg / L as CaCO3, acid consumption (pH 4.8) 225 mg / L as CaCO3, magnesium hardness 165 mg / L as CaCO3, chloride ion concentration 260 mg / L, sulfate ion concentration 270 mg / L, and pH 8.6. The material used in the test was the same SPCC test piece (30 mm × 50 mm × 1 mm) as in Test Example 1 above. One test piece was immersed in 1 L of test water, and the same corrosion test as in Test Example 1 was conducted. The test results were evaluated as follows: the corrosion loss was calculated from the weight difference of the test piece before and after the test, based on the formula used to calculate the corrosion rate (mm / y) in <Test Example 1> (where the specific gravity is 7.87 g / cm³). 3 ), calculate the corrosion rate (mm / y).

[0232] <Results>

[0233] Compared to Example 2, the overall corrosion rate tended to be lower, therefore the water quality itself is considered to be corrosion-resistant. The combination of AA-based polymer 1, MA-based polymer 1 or MA-based polymer 2, and iminodiamalic acid (the three components) showed particularly good corrosion resistance. This result means that even with changes in the type of dicarboxylic acid polymer, good corrosion resistance is maintained. Furthermore, the combination of sulfonated (meth)acrylic acid polymers (preferably acrylic polymers), corrosion-resistant organic acid compounds, and dicarboxylic acid polymers (preferably maleic acid polymers) is considered to provide even better corrosion resistance.

[0234] [Table 5]

[0235] Table 5 Evaluation of corrosion protection effect when combined

[0236]

[0237] <Experimental Example 4>

[0238] <Method>

[0239] Among combinations of (meth)acrylic acid polymers, dicarboxylic acid polymers, and corrosion-resistant organic acid compounds, (meth)acrylic acid polymers are considered to act as dispersants to maintain water quality and help prevent scale buildup. Therefore, the effect of the type of (meth)acrylic acid polymer on preventing precipitation in the test water was evaluated. The test water was adjusted to a calcium hardness of 300 mg / L CaCO3 and a pH of 8.5, and then immersed in a 90°C hot water bath for 1 hour. The turbidity of the aqueous solution after the test was confirmed.

[0240] <Results>

[0241] It was confirmed that the precipitation of test water was suppressed by using a sulfonated (meth)acrylic acid polymer. Therefore, it is expected that using a sulfonated (meth)acrylic acid polymer can help prevent scale buildup on heat transfer surfaces and maintain the concentration of corrosion inhibitors in water systems containing heat transfer surfaces. The results indicate that the combination of the sulfonated (meth)acrylic acid polymer and the corrosion-inhibiting organic acid compound provides even better corrosion protection and scale prevention. Furthermore, it is believed that the combination of these three components—the sulfonated (meth)acrylic acid polymer, the dicarboxylic acid polymer (preferably a maleic acid polymer), and the corrosion-inhibiting organic acid compound—can further enhance both corrosion protection and scale prevention.

[0242] [Table 6]

[0243] Table 6 Evaluation of the scale-preventing effect of (meth)acrylic polymers

[0244]

[0245] Furthermore, the above results show that in water systems containing metal materials that come into contact with water, by combining the aforementioned corrosion-resistant organic acid compounds and polymers with a specified or higher organic acid corrosion resistance index (especially one polymer having (meth)acrylic acid and sulfonic acid as monomers, or two or more different polymers having (meth)acrylic acid and sulfonic acid as monomers and dicarboxylic acid polymers), it is possible to achieve a more superior corrosion-resistant effect through the synergistic effect of these two or three components.

[0246] Specifically, it was found that in water systems containing metal materials in contact with water, using at least two components—a polymer with (meth)acrylic acid and sulfonic acid as monomers and an organic acid compound with an organic acid corrosion resistance index of 4 or higher—can achieve better metal corrosion protection and scale prevention. Furthermore, it was found that using a polymer with (meth)acrylic acid and sulfonic acid as monomers, a dicarboxylic acid polymer, and an organic acid compound with an organic acid corrosion resistance index of 4 or higher—can achieve excellent metal corrosion protection and scale prevention in water systems.

[0247] Furthermore, it has been found that by using the aforementioned corrosion-resistant organic acid compound with a specified or higher organic acid corrosion resistance index on polymers (especially one polymer having (meth)acrylic acid and sulfonic acid as monomers, or two or more different polymers having (meth)acrylic acid and sulfonic acid as monomers and dicarboxylic acid polymers), the corrosion-resistant effect of the polymer can be synergistically improved or enhanced into a superior corrosion-resistant effect.

[0248] Furthermore, regarding the anti-corrosion mechanism (hypothesis) of this embodiment, the inventors have conceived the following hypothesis, but many aspects remain unclear, and further in-depth research has been conducted on this mechanism. The inventors believe that the aforementioned anti-corrosion organic acid compound helps form anti-corrosion rust by acting on ions such as iron, inhibiting the dissolution reaction of metal in the corrosion reaction. The inventors believe that the sulfonated (meth)acrylic acid polymer maintains a moderately dispersed state and preserves the anti-corrosion effect in a manner that prevents scaling due to its calcium complex. The inventors believe that the dicarboxylic acid polymer combines with calcium to form a film on the metal surface, thereby inhibiting the oxygen reduction reaction in the corrosion reaction. The inventors further believe that when the sulfonated (meth)acrylic acid polymer and the dicarboxylic acid polymer are used in combination, the sulfonated (meth)acrylic acid polymer maintains a moderately dispersed state and preserves a better anti-corrosion effect in a manner that prevents scaling due to the dicarboxylic acid polymer and calcium complex.

[0249] As described above, the inventors are able to provide an aqueous metal corrosion protection method using a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, and an organic acid corrosion protection index of 4 or higher, preferably also using a dicarboxylic acid polymer. Furthermore, the inventors are able to provide an aqueous metal corrosion protection method or an aqueous metal corrosion inhibitor using a copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, a dicarboxylic acid polymer, and an organic acid corrosion protection index of 4 or higher.

[0250] Furthermore, since the aforementioned two or three components do not utilize phosphorus compounds and / or metal salt compounds, this method or agent does not impose any burden on the aquatic environment due to eutrophication and water toxicity caused by phosphorus compounds and / or metal salt compounds, and the overall burden on the aquatic environment can be significantly reduced. Moreover, the aforementioned two or three components exhibit good corrosion-preventing effects under the test water quality conditions; therefore, considering the water quality conditions of the test water, this method or agent can be applied across a wide range of water qualities.

[0251] That is, the inventors can also achieve the following objectives: to provide a water system metal corrosion prevention treatment method and a water system metal corrosion inhibitor that can exert a metal corrosion prevention effect in water systems even without utilizing phosphorus compounds and / or metal salt compounds that cause eutrophication and water toxicity, and that can be applied to a wide range of water quality. It should be noted that this method or agent can also utilize phosphorus compounds and / or metal salt compounds in water systems while considering reducing the impact on the water environment.

[0252] It should be noted that in this specification, numbers or letters such as "first, second, third…", "A, B, C…", "1st time, 2nd time, 3rd time…" are sometimes added for ease of description. However, this invention is not narrowly limited to the order of events, and the order can be arbitrarily changed. In addition, in this specification, for example, "management (matter)" or "performing (matter)" can be used as a method, process, means, or step, and these terms can be appropriately replaced. For example, "step" can be used as "performing (matter)," "method," "process," or "means," "process" can be used as "performing (matter)," "method," "step," or "means," and "means" can be used as "performing (matter)," "method," "process," or "step." Additionally, in this specification, "system" can refer to an organization, device, unit, or part; "organization" can refer to a system, device, unit, or part; "device" can refer to a system, organization, unit, or part; "unit" can refer to an organization, system, device, or part; "part" can refer to an organization, unit, device, or system, or an organization, unit, or device used in them, etc. Combined products can also be combined.

[0253] Explanation of reference numerals in the attached figures

[0254] 1 Open circulating cooling water system, 10 Open cooling tower, 11 Air supply unit, 12 Sprinkler unit, 13 Filling material area, 14 Space, 15 Groove, 16 Make-up water supply unit, 17 Chemical injection unit, 18 Ventilation outlet, 20 Circulating water path, 21 Transfer pump, 30 Heat exchanger.

Claims

1. A method for preventing corrosion of metal in a water system, wherein the following is applied: Copolymers of (meth)acrylic acid monomers and sulfonic acid monomers, Organic acid compounds with an anti-corrosion effect index of 4 or higher, and Dicarboxylic acid polymers, The copolymer has a weight-average molecular weight of 4000~30000. The corrosion-resistant organic acid compound is an organic acid compound having a carboxylic acid group and a hydroxyl group. No metal salt compounds with concentrations above 0.1 mg / L are added.

2. The method according to claim 1, wherein, The corrosion-resistant organic acid compound is iminodiamalic acid.

3. The method according to claim 1 or 2, wherein, The dicarboxylic acid polymer is selected from one or more of maleic acid polymers and polyepoxysuccinic acid.

4. The method according to claim 1 or 2, which is a corrosion prevention method for water systems used to suppress corrosion of metals in contact with water systems.

5. The method according to claim 1 or 2, wherein, The sulfonic acid monomer of the copolymer is a monomer having an amide group and a sulfonium group, or a monomer having a hydroxyl group and a sulfonium group, or a combination thereof.

6. The method according to claim 1 or 2, wherein, The sulfonic acid monomer of the copolymer is at least one monomer selected from 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and 3-allyloxy-2-hydroxypropanesulfonic acid (HAPS).

7. The method according to claim 1 or 2, wherein, The copolymer's (meth)acrylic acid monomer is an acrylic acid monomer.

8. The method according to claim 1 or 2, wherein, The copolymer has a (meth)acrylic acid monomer: sulfonic acid monomer molar ratio of 80:20 to 90:

10.

9. The method according to claim 1 or 2, wherein, The copolymer has a weight-average molecular weight of 4000 to 20000.

10. The method according to claim 1 or 2, wherein, The copolymer has a weight-average molecular weight of 4500~11000.

11. The method according to claim 3, wherein, The maleic acid polymer is a copolymer of maleic acid monomer and isobutylene monomer, and / or polymaleic acid.

12. The method according to claim 3, wherein, The weight-average molecular weight of the maleic acid polymer is 500-3000.

13. The method according to claim 1, wherein the corrosion resistance index of the corrosion-resistant organic acid compound is 5 or higher.

14. The method according to claim 1, wherein, The organic acid compound is selected from one or more of glucoheponic acid, tartaric acid, citric acid, mucoacid, 1,2,3,4-butanetetracarboxylic acid and iminodiamalic acid.

15. The method according to claim 3, wherein, The weight-average molecular weight of the dicarboxylic acid polymer is 500-3000.

16. A water-based metal corrosion inhibitor, comprising: (A) A copolymer of (meth)acrylic acid monomer and sulfonic acid monomer, (B) Dicarboxylic acid polymers, and (C) Corrosion-resistant organic acid compounds with an organic acid corrosion resistance index of 4 or higher. The copolymer has a weight-average molecular weight of 4000~30000. The corrosion-resistant organic acid compound is an organic acid compound having a carboxylic acid group and a hydroxyl group. Metal salt compounds with concentrations above 0.1 mg / L are not used in aquatic systems.

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