Corrosion prevention methods for water systems

Abstract

The present invention provides a technology relating to corrosion prevention of water systems for better suppressing corrosion of metals in contact with water. A corrosion prevention method for a water system for inhibiting corrosion of a metal in contact with the water system, comprising: A corrosion prevention method for an aqueous system, which uses a phosphorus compound, a film-forming amine, and a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer, the copolymer having a weight-average molecular weight of 500 to 100,000, in the aqueous system. A metal corrosion inhibitor containing a phosphorus compound, a film-forming amine, and a low-molecular-weight polymer having a weight-average molecular weight of 500 to 100,000, and a corrosion prevention method for an aqueous system, which uses the metal corrosion inhibitor to inhibit corrosion of metals in contact with water.

Description

[Technical Field]

[0001] The present invention relates to a method for preventing corrosion in an aqueous system, a metal corrosion inhibitor, a water treatment agent for preventing metal corrosion, a water treatment agent, and a method for preventing corrosion in an aqueous system using these agents to inhibit corrosion of metals in contact with water. [Background technology]

[0002] For example, metal components (e.g., heat exchangers, reactors, and piping made of carbon steel, copper, or copper alloys) installed in water systems such as open-circulating cooling water systems are susceptible to corrosion when they come into contact with water (e.g., cooling water) in the water system, and therefore are generally subjected to anticorrosion treatment by adding chemicals. For example, techniques using film-forming amines are being investigated to inhibit corrosion of carbon steel heat exchangers, reactors, piping, and the like in cooling water systems.

[0003] For example, Non-Patent Document 1 proposes a method using a film-forming amine as another method for inhibiting corrosion. The method described in Non-Patent Document 1 is mainly applied to inhibiting corrosion of iron-based members in boiler water systems. Non-Patent Document 1 discloses that the mechanism of corrosion prevention using a film-forming amine is that the film-forming amine adsorbs to the surface of the metal via amino groups to form a dense monomolecular or multimolecular layer film, thereby preventing contact between the metal and water and thereby inhibiting metal corrosion.

[0004] For example, Patent Document 1 proposes a corrosion prevention method in which a film-forming amine and an M alkalinity component are made to coexist in a cooling water system, thereby forming a corrosion-preventing film on the surface of a metal component in contact with the cooling water system and suppressing corrosion of the metal component, characterized in that a neutralizing amine is used as the M alkalinity component and the M alkalinity of the cooling water system is adjusted to 90 mg / L as CaCO3 or more during the initial treatment to form the corrosion-preventing film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2019 / 078104 [Non-patent literature]

[0006] [Non-Patent Document 1] Corrosion Center News No. 054 (August 2010) Water Treatment Technology (1) "Corrosion and Corrosion Prevention of Boilers and Peripheral Equipment" by Fumio Kawamura Summary of the Invention [Problem to be solved by the invention]

[0007] However, conventionally, film-forming amines themselves have a weak corrosion inhibitory effect, and when film-forming amines are used as scale removers in open circulating cooling water systems, there have been cases where the corrosion of materials in between them has been a concern.

[0008] Therefore, a main object of the present invention is to provide a technique relating to corrosion prevention in water systems to better inhibit corrosion of metals in contact with water. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the combined use of a phosphorus compound, a film-forming amine, and a polymer (preferably a (meth)acrylic acid-based copolymer and / or a low-molecular-weight polymer) can better inhibit corrosion of metals in contact with water. They have also found that the combined use of the film-forming amine and the polymer can better enhance the metal corrosion protection provided by the phosphorus compound. That is, the present inventors have completed the following invention.

[0010] The present invention provides a corrosion prevention method for an aqueous system for inhibiting corrosion of a metal in contact with the aqueous system, The present invention provides a corrosion prevention method for an aqueous system, which uses a phosphorus compound, a film-forming amine, and more than 5 mg / L of a copolymer of a (meth)acrylic acid monomer and a sulfonic group-containing monomer having a weight-average molecular weight of 500 to 100,000 in the aqueous system.

[0011] The present invention also provides a coating composition comprising a phosphorus compound, a film-forming amine, and a low-molecular-weight polymer having a weight-average molecular weight of 500 to 100,000, The polymer is included for use at dosages greater than 5 mg / L. The present invention provides a metal corrosion inhibitor.

[0012] The present invention also provides a water treatment agent containing at least one of a phosphorus compound, a film-forming amine, and a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer having a weight-average molecular weight of 500 to 100,000, and when used for metal corrosion prevention in an aqueous system, the water treatment agent is used in combination with the phosphorus compound, the film-forming amine, and the copolymer of the (meth)acrylic acid monomer and the sulfonic acid group-containing monomer in an aqueous system, The copolymer is included for use at a dosage of greater than 5 mg / L. The present invention provides a water treatment agent for metal corrosion prevention.

[0013] The present invention also provides a water treatment agent containing a film-forming amine and / or a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer having a weight-average molecular weight of 500 to 100,000, wherein the water treatment agent is used in an aqueous system by using the film-forming amine and the copolymer of the (meth)acrylic acid monomer and the sulfonic acid group-containing monomer in combination to strengthen metal corrosion prevention by a phosphorus compound, The copolymer is included for use at a dosage of greater than 5 mg / L. The present invention provides a water treatment agent.

[0014] The copolymer may be a copolymer of a (meth)acrylic acid monomer and a monomer containing an amide group or a hydroxy group and a sulfonic acid group. The film-forming amine may be an aliphatic amine compound. The phosphorus compound may be a phosphonic acid compound. When a film-forming amine is used in the aqueous system, the copolymer of the (meth)acrylic acid monomer and the sulfonic acid group-containing monomer may be used in combination. The water system may be a cooling water system. The present invention can also provide a corrosion prevention method for a water system for inhibiting corrosion of metals in contact with water, which method comprises using the agent. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a technology relating to corrosion prevention of aqueous systems for better suppressing corrosion of metals in contact with water. Note that the effects of the present invention are not necessarily limited to the effects described herein, and may be any of the effects described in this specification. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing an example of a water system used in the method of the present embodiment, for example, an example of a circulating cooling water system having a cooling tower, but the present invention is not limited thereto. [Figure 2] FIG. 1 is a schematic diagram of a rotating corrosion test apparatus used in this test. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments for carrying out the present invention will be described below. Note that the embodiment described below shows one example of a typical embodiment of the present invention, and the scope of the present invention should not be construed as being narrow. Furthermore, percentages in this specification are expressed by mass (mass / mass%) unless otherwise specified. Furthermore, the upper limit (or less) and lower limit (or more) of each numerical range (to) can be arbitrarily combined as desired.

[0018] 1. Method for preventing corrosion of metals in an aqueous system according to this embodiment

[0019] The present invention provides a corrosion prevention method for an aqueous system for inhibiting corrosion of a metal in contact with the aqueous system, comprising the use of a phosphorus compound, a film-forming amine, and a polymer in the aqueous system. The corrosion prevention method for an aqueous system may also be a corrosion prevention treatment method for an aqueous system. The polymer is preferably a low-molecular-weight and / or (meth)acrylic acid-based polymer. More specifically, examples include low-molecular-weight polymers, (meth)acrylic acid-based polymers, and low-molecular-weight (meth)acrylic acid-based polymers, and it is preferable to select and use one or more of these. More preferably, the polymer is a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer having a weight-average molecular weight of 500 to 100,000.

[0020] The present invention provides a technology for aqueous corrosion prevention that better inhibits corrosion of metals in contact with water. Furthermore, the present invention provides a technology that can better enhance metal corrosion prevention by the phosphorus compound by using the film-forming amine in combination with the polymer, thereby providing a technology for aqueous metal corrosion prevention treatment that can reduce the amount of phosphorus compound or phosphorus used. The present invention provides a technology that can enhance the corrosion prevention ability of metal materials used in aqueous systems or cooling water systems (preferably circulating cooling water, more preferably open-circulating cooling water systems). Furthermore, the present invention provides a technology that can enhance the corrosion prevention ability of metal materials during scale removal in aqueous systems, thereby enabling the life of metal materials to be extended.

[0021] In the prior art, film-forming amines are added to aqueous systems to protect metal components in the systems from corrosion. For example, steam corrosion inhibitors for boilers and the like have been proposed, and the combination of copper corrosion inhibitors and acid consumption has been proposed to enhance corrosion protection for metal materials. Furthermore, their use as on-line scale removers in open circulating cooling water systems has also attracted attention. However, the corrosion inhibitory power of film-forming amines themselves is weak, and there have been cases where the corrosiveness of materials during their use as scale removers has been a concern.

[0022] In contrast to this, the present invention provides a technology that, when a film-forming amine is used as a scale remover (preferably an on-line scale remover), further uses a low-molecular-weight and / or (meth)acrylic acid-based polymer, thereby strengthening the corrosion prevention ability and suppressing corrosion of materials during scale removal. In this specification, the term "On-Line" in "On-Line scale remover" refers to removing scale by operating the water system without stopping the operation of the water system (such as the operation of a plant) (for example, continuous operation or circulation using a circulating water system). Furthermore, in this embodiment, by operating the water system, the chemical agent used or the water containing the chemical agent is in contact with components in the water system (e.g., metal components, the inside of piping, etc.) during the operation period of the water system, thereby achieving both an anti-corrosion effect and a scale-inhibiting effect.

[0023] This embodiment will be described in detail below.

[0024] In this embodiment, the target of corrosion protection is, but is not limited to, a metal material. Examples of the metal material include one or more selected from carbon steel, copper, galvanized steel, zinc, aluminum, aluminum alloys, stainless steel, and alloys thereof. Among the metal materials, iron-based materials are preferred. Examples of the iron-based materials include iron materials in general (e.g., pure iron, carbon steel, cast iron, etc.). More preferred are carbon steel materials commonly used for carbon steel pipes for boilers and heat exchangers (e.g., STB steel pipes). According to JIS G 0203, carbon steel has a carbon content of 0.02% to approximately 2% by mass. More specifically, carbon steel with a carbon content of 0.25% or less by mass is called low-carbon steel, 0.25 to 0.6% by mass is called medium-carbon steel, and 0.6% or more by mass is called high-carbon steel. Because low-carbon steel to medium-carbon steel is widely used, carbon steel with a carbon content of 0.6% or less by mass is also called ordinary steel. Cast iron is said to have a carbon content of more than 2% by mass. In this embodiment, among these, ordinary steel, low-carbon steel, and medium-carbon steel, and more preferably low-carbon steel, can exhibit a better corrosion prevention effect.

[0025] The object of anticorrosion treatment to which this embodiment is suitably applied is preferably a metal material that comes into contact with water or a metal member that uses a metal material that comes into contact with water. Examples of locations or devices in a water system that use metal materials or metal components include various types of piping such as water supply piping, pipes, pumps, flow paths, heat exchangers, freezers, etc., and one or more types selected from these may be used. More specifically, these or metal parts or portions thereof are targets of the corrosion prevention treatment to which this embodiment is suitably applied.

[0026] 1-1. Phosphorus compounds The phosphorus compound used in this embodiment is preferably a phosphorus oxoacid compound having at least P(=O)(-OH). Suitable phosphorus compounds include, for example, phosphonic acid compounds, phosphinic acid compounds, and phosphoric acid compounds, and one or more of these can be selected. These compounds may be in the form of a salt, and the salt is not particularly limited, and examples thereof include alkali metals (e.g., sodium, potassium, etc.) and alkaline earth metals (e.g., calcium, magnesium, etc.), and one or more of these can be used.

[0027] The phosphorus compound is preferably one that can be used in aqueous systems (preferably water treatment such as corrosion prevention), and more preferably one that is water-soluble. The phosphorus compound is preferably one that has a scale inhibitory effect, and is preferably one that can be used as a membrane scale inhibitor. The phosphorus compound is preferably one that captures metal ions (e.g., Ca, Al, etc.), and is preferably one that can be used as a phosphate compound-based scale inhibitor or a phosphonate compound-based scale inhibitor. The form of the phosphorus compound of this embodiment is not particularly limited, and may be any of liquid, solid, and semi-solid, with liquid being preferred for ease of handling. The phosphorus compound used in this embodiment may be a commercially available product, or may be one obtained by a known production method.

[0028] Of the above phosphorus compounds, organic phosphorus compounds are preferred, and phosphonic acid compounds are more preferred, from the viewpoint of exhibiting a better anticorrosion effect. When an organic phosphorus compound (preferably a phosphonic acid compound) is used, it may be used in combination with a phosphoric acid compound.

[0029] The phosphonic acid compound is preferably a compound having at least a phosphonic acid group, and is preferably an organic phosphorus compound. Examples of the phosphonic acid compound include 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC, also known as 2-phosphono-1,2,4-tricarboxybutane), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP, also known as 1-hydroxyethane-1,1-diphosphonic acid), 2-hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediaminetetra(methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and salts thereof. One or more of these compounds can be selected. Among these compounds, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and / or 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) are preferred. One or more of these compounds can be used.

[0030] The phosphinic acid compound is a compound having at least a phosphinic acid group, and examples thereof include phosphinic acid salts, such as bis(poly-2-carboxyethyl)phosphinic acid, phosphinocarboxylic acid copolymers, and salts thereof. Among these, phosphinocarboxylic acid salts are preferred. One or more of these may be used. One or more of the phosphorus compounds may be appropriately selected from the examples of the phosphorus compounds described above.

[0031] The phosphate compound is preferably a compound containing at least a phosphate group, and is preferably a compound capable of generating phosphate ions in water in an aqueous system, with inorganic phosphate compounds being more preferred. Examples of the phosphate compound include phosphorus, phosphoric anhydride, phosphoric acid (also known as orthophosphoric acid or orthophosphoric acid); polymeric phosphoric acids (e.g., linear polyphosphoric acids such as pyrophosphoric acid, tripolyphosphoric acid, orthopolyphosphoric acid, and decametaphosphoric acid; cyclic polyphosphoric acids such as hexametaphosphoric acid; and salts thereof), from which one or more can be selected. The number of phosphorus atoms in the phosphate compound is not particularly limited, but may be, for example, 1 to 10, and examples include orthophosphoric acid (one atom) and pyrophosphoric acid (two atoms).

[0032] The concentration (mg PO4 / L, hereinafter referred to as "mg / L") of the phosphorus compound used in an aqueous system is not particularly limited, but is preferably 0.1 to 10 mg / L, more preferably 3 to 6 mg / L, and it is suitable to add the phosphorus compound so as to achieve such a concentration. In a more preferred embodiment, the concentration (mg PO4 / L) of the phosphonic acid compound used in an aqueous system is preferably 0.1 to 10 mg / L, more preferably 3 to 6 mg / L. In addition, the use concentration of the phosphorus compound or the like described above can also appropriately adopt the preferred upper and lower limit values ​​described in "Use amount of the phosphorus compound (preferably a phosphonic acid compound) relative to the aqueous system" in "1-4." described below. The concentration of phosphorus compounds (mg PO4 / L) can be measured using the molybdenum blue (ascorbic acid reduction) method (JIS K 0102 46.1.1).

[0033] 1-2. Film-forming amines The film-forming amine used in this embodiment is not particularly limited, but is preferably an amine capable of forming an effective anticorrosion film that inhibits corrosion on metal materials in contact with water. The film-forming amine may be a film-forming amine typically used as a corrosion inhibitor in aqueous systems such as boiler water systems or cooling water systems, or may be a film-forming amine commonly used in aqueous systems. The film-forming amine may be one or more aliphatic amine compounds (e.g., aliphatic monoamine compounds, aliphatic diamine compounds, etc.). In this specification, "aliphatic amine compounds" may also be expressed as "aliphatic amines." Since film-forming amines are poorly soluble in water, they may be used by dissolving them in an oil or dispersing them in water as an emulsion.

[0034] The present embodiment has the advantage that the combined use of at least the film-forming amine and the polymer can enhance the corrosion prevention effect and can aim to inhibit corrosion of materials (e.g., metal materials) during descaling. Moreover, when the film-forming amine is used as an online scale remover, it can exhibit a better corrosion prevention effect.

[0035] The aliphatic amine compound (aliphatic amines) preferably has one or two nitrogen atoms and an aliphatic group bonded to at least one nitrogen atom. The aliphatic amine compound (aliphatic amines) is not particularly limited, and examples thereof include aliphatic amines, salts thereof, and derivatives thereof, and one or more selected from these can be used. More preferred examples include aliphatic monoamine compounds and aliphatic diamine compounds, and one or more selected from these can be used.

[0036] The aliphatic amine compound (aliphatic amines) is preferably a long-chain aliphatic amine compound (long-chain aliphatic amines). The number of carbon atoms in the long-chain aliphatic group is not particularly limited as long as it is capable of forming a corrosion-resistant coating, and is preferably 10 to 22, more preferably 12 to 20, and even more preferably 16 to 18. When the number of carbon atoms is 10 or more, a coating can be easily formed on the metal member and the corrosion-inhibiting function can be effectively exhibited. When the number of carbon atoms is 22 or less, the handling during chemical injection tends to be excellent and good.

[0037] The aliphatic group constituting the aliphatic amine compound (aliphatic amines) may contain an unsaturated bond. Furthermore, the hydrogen moiety of the amino group constituting the aliphatic amine compound may be appropriately substituted with a hydrocarbon group such as a methyl group or an ethyl group. Furthermore, the aliphatic amine may be a fatty acid salt (e.g., a mixed amine compound). In this case, the fatty acid moiety constituting the fatty acid salt may be, for example, one or more selected from oleic acid, lauric acid, stearic acid, etc. When the aliphatic amine compound is a fatty acid salt, the raw material may be, for example, one or more selected from animal fats and oils, vegetable fats and oils, and microbial fats and oils, with animal and vegetable fats and oils being preferred.

[0038] Specific preferred examples of the aliphatic amine compound (aliphatic amines) include saturated aliphatic amine compounds (alkylamines), unsaturated aliphatic amine compounds (alkynylamines), mixed amine compounds (e.g., coconut oil amine, hardened beef tallow amine, etc.), and alkylene oxide adducts of aliphatic amine compounds, and one or more selected from these can be used. Furthermore, "alkylene oxide adducts of aliphatic amine compounds" include those obtained by addition polymerization of ethylene oxide or propylene oxide to aliphatic mixed amines, etc.

[0039] The aliphatic group in the aliphatic amine compound may be either acyclic or cyclic, more specifically, either chain (straight chain or branched chain) or alicyclic (non-aromatic ring), with chain being preferred. The aliphatic group is preferably a saturated aliphatic group, more preferably an alkyl group or alkylene group, which may have an appropriate substituent.

[0040] Examples of the aliphatic monoamine compound include, but are not limited to, an "aliphatic group-amino group" structure. Examples of the aliphatic diamine compound include, but are not limited to, a compound in which the hydrogen atom of at least one amino group is substituted with an aliphatic group, and a compound having a divalent aliphatic group between the nitrogen atom of one amino group and the nitrogen atom of the other amino group. Examples of the aliphatic diamine compound include, but are not limited to, an "amino group-divalent aliphatic group-amino group" structure, and it is preferable that at least one of the amino groups is an "aliphatic group-amino group" structure, such as "RR'N-divalent aliphatic group-NH2" in trimethylenediamine (also known as "diaminopropane"). The divalent aliphatic group may be either linear (linear or branched) or alicyclic, but is preferably linear. The "amino group" refers to a monovalent functional group (-NH2, -NHR, -NRR') obtained by removing hydrogen from ammonia, a primary amine, or a secondary amine. R and R' may each be hydrogen, one may be hydrogen and the other may be an alkyl group, or they may be the same or different alkyl groups.

[0041] The divalent aliphatic group is preferably a divalent saturated or unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group, and even more preferably a chain C1 to C4 alkylene group (preferably a methylene group or an ethylene group), such as -(CH2)n- (wherein n = 1 to 4), or a diethylene group (n = 2) or a triethylene group (n = 3).

[0042] Examples of the aliphatic amine compound (preferably a long-chain aliphatic amine compound) include saturated aliphatic monoamine compounds (e.g., dodecylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, octadecylamine, nonadecylamine, eicosylamine, docosylamine, etc.), unsaturated aliphatic monoamine compounds (e.g., oleylamine, ricinoleylamine, linoleylamine, linolenylamine, etc.), mixed monoamine compounds (e.g., coconut oil amine, hardened beef tallow amine, etc.), diamino compounds having an aliphatic group in the amino group (for example, alkylpropanediamines (the alkyl preferably has 16 to 18 carbon atoms), N,N-diethyl-1,3-propanediamine, N-oleyl-1,3-diaminopropane, N-tallow-1,3-diaminopropane, N-coco-1,3-diaminopropane, etc.); alkylene oxide adducts such as N-tallow-1,3-diaminopropane-ethylene oxide adduct, etc., and one or more selected from these may be used.

[0043] Of the aliphatic amine compounds (aliphatic amines), aliphatic monoamine compounds and / or aliphatic diamine compounds are preferred, aliphatic diamine compounds are more preferred, and it is even more preferred that these are long-chain aliphatic compounds.

[0044] The concentration (mg / L, hereinafter referred to as "mg / L") of the film-forming amine (preferably an aliphatic amine compound, more preferably an aliphatic diamine compound) when used in an aqueous system is not particularly limited, but is preferably 5 to 70 mg / L, more preferably 10 to 50 mg / L. The film-forming amine is preferably added to achieve such a concentration, and the concentration may be the concentration used when used online. In a more preferred embodiment, the concentration of the aliphatic diamine compound when used in an aqueous system is more preferably 5 to 70 mg / L, even more preferably 10 to 50 mg / L. Furthermore, the concentration of the film-forming amine or the like used may also be selected from the preferred upper and lower limit values ​​described in "Amount of the film-forming amine (preferably an aliphatic amine compound, more preferably an aliphatic diamine compound) used relative to the aqueous system" in "1-4." described below.

[0045] 1-3.Polymers The polymer used in this embodiment is not particularly limited, and is preferably an organic polymer compound that can be used in an aqueous system, more preferably a low-molecular-weight polymer and / or a water-soluble polymer. Among the polymers used in this embodiment, (meth)acrylic acid-based polymers are preferred, more preferably (meth)acrylic acid-based polymers containing sulfonic acid groups in the molecule, and even more preferably (meth)acrylic acid-based polymers containing sulfonic acid groups in the molecule. Among these, AA / AMPS-based polymers and AA / HAPS-based polymers are preferred. Furthermore, the polymer used in this embodiment may be a homopolymer obtained from the same monomer, but a copolymer obtained using different monomers is preferred. Polymers used as scale inhibitors for cooling water systems can be suitably used as the polymer used in this embodiment. The form of the polymer salt is not particularly limited, and is preferably a salt that can convert a monomer or polymer into a water-soluble salt. Examples of such salts include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium and magnesium, and ammonium salts such as ammonium and primary to tertiary amines. One or more selected from these can be used.

[0046] Examples of the polymer used in this embodiment include homopolymers or copolymers obtained by polymerizing or copolymerizing one or more monomers selected from the group consisting of (meth)acrylic acid (acrylic acid and / or methacrylic acid), (meth)acrylic acid compounds such as 2-hydroxyethyl methacrylate (HEMA), monomers containing sulfonic acid groups such as 1-propanesulfonic acid (HAPS), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), styrenesulfonic acid (SS), and isoprenesulfonic acid (IPS), isobutylene (IB), and maleic acid. Note that (meth)acrylic acid compound monomers other than (meth)acrylic acid may also be used, such as (meth)acrylic acid compounds having esters, hydroxyl groups, or amino groups, but (meth)acrylic acid is preferred.

[0047] Among the above polymers, (meth)acrylic acid polymers are preferred, and copolymers of (meth)acrylic acid monomers and sulfonic acid monomers are more preferred. Specific examples of more preferred polymers include homopolymers or copolymers 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), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and the like.

[0048] The weight average molecular weight of the polymer (preferably a (meth)acrylic acid-based polymer) is not particularly limited, but is preferably a low molecular weight, and a suitable lower limit is preferably 500 or more, more preferably 1,000 or more, more preferably 4,000 or more, more preferably 5,000 or more, and a suitable upper limit is preferably 100,000 or less, more preferably 50,000 or less, more preferably 30,000 or less, more preferably 20,000 or less, and more specifically, more preferred numerical ranges are preferably 500 to 100,000, more preferably 1,000 to 50,000, more preferably 4,000 to 30,000, more preferably 5,000 to 20,000. The weight average molecular weight of the polymer in this specification can be obtained by gel permeation chromatography (GPC analysis) using a standard substance, and when sodium polyacrylate is used as the standard substance, the value is calculated as sodium polyacrylate.

[0049] 1-3-1.(Meth)acrylic acid polymers The polymer used in this embodiment is preferably a (meth)acrylic acid polymer, more preferably a (meth)acrylic acid copolymer, and more specifically, a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer, and even more preferably a copolymer of a (meth)acrylic acid monomer and an amide group- and sulfonic acid group-containing monomer. The monomer ratio (molar ratio (mol %)) of the (meth)acrylic acid monomer to the sulfonic acid group-containing monomer in the (meth)acrylic acid copolymer is preferably 99 to 1:1 to 99. The (meth)acrylic acid copolymer is preferably low in molecular weight.

[0050] <(Meth)acrylic acid monomer> The (meth)acrylic acid monomer is not particularly limited, and examples thereof include (meth)acrylic acid and salts thereof, and one or more selected from this group can be used. In this embodiment, "(meth)acrylic acid" means at least one selected from the group consisting of "acrylic acid" and "methacrylic acid". Among these, acrylic acid or a salt thereof is preferred. In addition, when the (meth)acrylic acid monomer used in this embodiment contains a sulfonic acid group, it is preferred to use this monomer as a sulfonic acid monomer, and it is more preferred that the (meth)acrylic acid monomer used in this embodiment is a monomer other than a (meth)acrylic acid monomer containing a sulfonic acid group.

[0051] <Sulfonic acid monomer> The sulfonic acid monomer is not particularly limited, but a monomer containing a sulfonic acid group is preferred from the viewpoint of exhibiting a better corrosion prevention effect, and the monomer is more preferably an unsaturated monomer. Examples of the sulfonic acid monomer include, but are not limited to, monoethylenically unsaturated sulfonic acid monomers and salts thereof, and among these, monoethylenically unsaturated sulfonic acid monomers are preferred.

[0052] Examples of the sulfonic acid monomer include monomers having an amide group and a sulfonic acid group (preferably having 6 to 9 carbon atoms), monomers having a hydroxy group and a sulfonic acid group (preferably having 6 to 9 carbon atoms), sulfonated products of aliphatic conjugated dienes (preferably having 4 to 15 carbon atoms), and salts thereof. One or more selected from these groups can be used. Among these, monomers having an amide group and a sulfonic acid group (preferably having 6 to 9 carbon atoms) and monomers having a hydroxy group and a sulfonic acid group (preferably having 6 to 9 carbon atoms) are preferred. The "sulfonic acid group" of the monomer may be a sulfonic acid group that may have a substituent, such as an alkylsulfonic acid group. The "alkyl" in the alkylsulfonic acid group preferably has 1 to 8 carbon atoms, and a methylpropanesulfonic acid group (also known as a tert-butylsulfonic acid group) is more preferred. This allows for better corrosion prevention.

[0053] Examples of the monomer having an amide group and a sulfonic acid group include (meth)acrylamidoalkylpropanesulfonic acid, crotonamidoalkylpropanesulfonic acid, etc. More specifically, examples include 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 3-acrylamido-3,3-dimethylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 3-methacrylamido-3,3-dimethylpropanesulfonic acid, etc., and salts thereof, and one or more selected from this group can be used.

[0054] Examples of the monomer containing a hydroxy group and a sulfonic acid group include 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 salts thereof, and one or more selected from this group can be used.

[0055] Examples of the sulfonated aliphatic conjugated dienes include sulfonated 1,3-butadiene and sulfonated 2,3-dimethyl-1,3-butadiene, and one or more selected from this group can be used.

[0056] More preferred sulfonic acid monomers include sulfonic acid group-containing unsaturated monomers such as (meth)acrylamidomethylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, (meth)allyl sulfonic acid, vinyl sulfonic acid, styrenesulfonic acid, and 2-sulfoethyl methacrylate, as well as salts thereof. One or more selected from this group can be used. Among these, at least one monomer selected from 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and 3-allyloxy-2-hydroxypropanesulfonic acid (HAPS) is preferred, with AMPS and / or HAPS being more preferred. This allows for better corrosion prevention.

[0057] <Production Example of (Meth)acrylic Acid Copolymer> The (meth)acrylic acid copolymer can be produced by a known production method. A suitable copolymer is a polymer obtained by copolymerizing (i) a (meth)acrylic acid monomer and (ii) one or more sulfonic acid monomers selected from a monomer having an amide group and a sulfonic acid group, a monomer containing a hydroxy group and a sulfonic acid group, etc., in a predetermined mass ratio. Any monomer may be used as long as it does not impair the effects of the present invention.

[0058] A more preferred (meth)acrylic acid copolymer is a polymer obtained by copolymerizing (i) an acrylic acid monomer and (ii) at least one sulfonic acid monomer selected from 2-acrylamido-2-methylpropanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid in a predetermined mass usage ratio. An even more preferred (meth)acrylic acid copolymer is one or more selected from the group consisting of a copolymer of an acrylic acid monomer and a 2-acrylamido-2-methylpropanesulfonic acid monomer, a copolymer of an acrylic acid monomer and a 3-allyloxy-2-hydroxypropanesulfonic acid monomer, etc., and in this case, a more preferred predetermined molar ratio of the (meth)acrylic acid monomer to the sulfonic acid monomer is, for example, 1 to 99:99 to 1, and the molar ratio can be appropriately selected from the <Molar ratio (mol %) in the (meth)acrylic acid copolymer> described below. This allows for the production of a polymer that exhibits better anticorrosion effects.

[0059] <Molar Ratio (Mole %) of the (Meth)acrylic Acid Monomer to the Sulfonic Acid Monomer> The molar ratio (mol %: when the total amount of both is taken as 100) of the (meth)acrylic acid monomer to the sulfonic acid monomer in component (A), a copolymer of a (meth)acrylic acid monomer and a sulfonic acid monomer, is not particularly limited. However, a suitable lower limit for the (meth)acrylic acid monomer is preferably 10 or more, more preferably 40 or more, even more 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. A suitable upper limit for the (meth)acrylic acid monomer is preferably 99 or less, more preferably 98 or less, even more preferably 95 or less, more preferably 93 or less, and even more preferably 90 or less. A more suitable numerical range for the molar ratio of the acrylic acid monomer to the sulfonic acid monomer is more preferably 50-99:50-1, even more preferably 60-95:40-5, and more preferably 75-90:25-10. By adjusting the component (A) copolymer to these molar ratios, better corrosion prevention effects can be achieved. The molar ratio may be appropriately adopted as the molar ratio (%) of each of the (meth)acrylic acid monomer and the sulfonic acid monomer to constitute a copolymer such as an AA / AMPS-based polymer or an AA / HAPS-based polymer, which will be described later.

[0060] In a more preferred embodiment of the molar ratio of the copolymer, the molar ratio (mol %) of the (meth)acrylic acid monomer to the sulfonic acid monomer containing an amide group and / or a hydroxyl group in the copolymer of the (meth)acrylic acid monomer and the sulfonic acid monomer containing an amide group and a hydroxyl group is more preferably 60-95:40-5, more preferably 75-90:25-10, and by adjusting the molar ratio to this value, a better corrosion prevention effect can be exhibited. Note that the molar ratio can be determined as appropriate from the preferred lower limit and preferred upper limit of the "molar ratio of the (meth)acrylic acid monomer to the sulfonic acid monomer" described above.

[0061] In a more preferred embodiment of the molar ratio of the copolymer, in the case of an AA / AMPS-based polymer or an AA / HAPS-based polymer, the AA / AMPS ratio or AA / HAPS ratio (mol %) (AA:AMPS or HAPS) is preferably (AA) 50-99:50-1, more preferably (AA) 60-95:40-5, and even more preferably (AA) 75-90:25-10. By adjusting the molar ratio in this manner, a better corrosion prevention effect can be exhibited. The molar ratio can be determined by appropriately adopting the preferred lower and upper limits of the "molar ratio between (meth)acrylic acid monomer and sulfonic acid monomer" described above.

[0062] <Weight-average molecular weight of (meth)acrylic acid copolymer> The weight average molecular weight of the copolymer of (meth)acrylic acid monomer and sulfonic acid monomer as measured by GPC is not particularly limited, but the lower limit is preferably 500 or more, more preferably 1,000 or more, even more preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, and more preferably 5,000 or more, and the upper limit is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 40,000 or less, more preferably 30,000 or less, and more preferably 20,000 or less. The preferred range of the (meth)acrylic acid monomer and sulfonic acid monomer is more preferably 4,000 to 30,000, and desirably 5,000 to 20,000. The preferred weight-average molecular weight of the AA / AMPS polymer and the AA / HAPS polymer can be set within the above-mentioned preferred upper and lower limits, but the preferred range is preferably 4,000 to 30,000, and more preferably 5,000 to 20,000. By adjusting the weight-average molecular weight within the range, better corrosion prevention effects can be achieved.

[0063] The concentration (mg solid / L, hereinafter referred to as "mg / L") of the polymer (preferably a low-molecular-weight and / or (meth)acrylic acid-based polymer) used in an aqueous system is not particularly limited, but is preferably 3 to 30 mg / L, more preferably 5 to 20 mg / L, and even more preferably 6 to 20 mg / L. The polymer is preferably added to achieve such a concentration. Furthermore, in a preferred embodiment, the concentration of the (meth)acrylic acid-based polymer (more preferably a (meth)acrylic acid-based polymer containing a sulfonic acid group) used in an aqueous system is not particularly limited, but is preferably 3 to 30 mg / L, more preferably 5 to 20 mg / L, and even more preferably 6 to 20 mg / L. Furthermore, the concentration of the AA / AMPS-based polymer and / or the AA / HAPS-based polymer used in an aqueous system is not particularly limited, but is preferably 3 to 30 mg / L, more preferably 5 to 20 mg / L, and even more preferably 6 to 20 mg / L. Furthermore, the use concentration of the polymer etc. described above can also appropriately adopt the preferred upper and lower limit values ​​described in "Use amount of the polymer (preferably a low-molecular-weight and / or (meth)acrylic acid-based polymer)" in "1-4." described later.

[0064] 1-4. Use of the phosphorus compound, the film-forming amine, and the polymer in combination, and suitable amounts and proportions of each component In this embodiment, in a corrosion prevention method for an aqueous system for suppressing corrosion of metals in contact with the aqueous system, at least three components, i.e., the phosphorus compound, the film-forming amine, and the polymer, are used, and by having these three components present in the aqueous system, a better metal corrosion prevention effect can be achieved. The following describes more suitable amounts and proportions of each component used in the aqueous system, as well as the content and blending ratio of each component in the agent.

[0065] In another aspect of the present embodiment, by using the film-forming amine and the polymer in combination in an aqueous system, it is possible to provide a technology for enhancing metal corrosion protection by a phosphorus compound present in or used in the aqueous system, and more preferable mass use ratios or mass content ratios in the agent will be described below.

[0066] The operating period in the aqueous system in this embodiment is not particularly limited, but may be extended to achieve or maintain a better corrosion prevention effect. A suitable lower limit is, for example, 0.5 months or more, preferably 1 month or more, more preferably 2 months or more, and even more preferably 3 months or more. The suitable upper limit is not particularly limited, but is preferably 6 months or less, more preferably 5 months or less, and even more preferably 4 months or less. A preferred range is more preferably 2 to 4 months. During this period, it is preferable to operate the system so that the film-forming amine and the polymer are in contact with the metal material at least continuously or cyclically. The operating period may also be the period of use.

[0067] <Suitable Amounts of the Phosphorus Compound, the Film-Forming Amine, and the Polymer> In this embodiment, the "usage concentration (mg / L)" may be expressed as the "usage amount (mg / L)" or the "addition amount (mg / L)," the "usage amount (mg / L)" may be expressed as the "usage concentration (mg / L)" or the "addition amount (mg / L)," and the "addition amount (mg / L)" may be expressed as the "usage concentration (mg / L)" or the "usage amount (mg / L)."

[0068] The amount of the phosphorus compound (preferably a phosphonic acid compound) used in the aqueous system (mg PO4 / L, hereinafter referred to as "mg / L") is not particularly limited, but a suitable lower limit is preferably 0.1 mg / L or more, more preferably 0.5 mg / L or more, even more preferably 1 mg / L or more, more preferably 2 mg / L or more, more preferably 3 mg / L or more, and a suitable upper limit is not particularly limited, but from the viewpoint of reducing the amount of agent used and balancing the anticorrosion effect, it is preferably 20 mg / L or less, more preferably 15 mg / L or less, even more preferably 10 mg / L or less, more preferably 8 mg / L or less, more preferably 5 mg / L or less. The preferred numerical range is more preferably 0.1 to 10 mg / L, and even more preferably 3 to 6 mg / L.

[0069] In a more preferred embodiment, the amount of the phosphonic acid compound used (mg PO4 / L) relative to the aqueous system can be set to any of the preferred lower and upper limits of the amount of the phosphorus compound used, and a more preferred range is more preferably 0.1 to 10 mg / L, and even more preferably 1 to 5 mg / L.

[0070] In addition, as a more preferred aspect of this embodiment, the above-mentioned phosphorus compound is preferably used continuously or discontinuously in an aqueous system (preferably a cooling water system), and more preferably added to blowdown water.

[0071] The amount (mg / L, hereinafter "mg / L") of the film-forming amine (preferably an aliphatic amine compound, more preferably an aliphatic diamine compound) used in the aqueous system is not particularly limited, but a preferred lower limit is preferably 0.1 mg / L or more, more preferably 0.5 mg / L or more, even more preferably 1 mg / L or more, more preferably 3 mg / L or more, more preferably 5 mg / L or more, more preferably 8 mg / L or more, and even more preferably 10 mg / L or more. Also, a preferred upper limit is not particularly limited, but from the viewpoint of a balance between reducing the amount of agent used and exhibiting anticorrosion effect, it is preferably 100 mg / L or less, more preferably 80 mg / L or less, even more preferably 70 mg / L or less, more preferably 60 mg / L or less, and even more preferably 50 mg / L or less. The preferred numerical range is more preferably 5 to 70 mg / L, and even more preferably 10 to 50 mg / L.

[0072] In a more preferred embodiment of the present invention, the film-forming amine is preferably used continuously or discontinuously in an aqueous system (preferably a cooling water system), more preferably added continuously or discontinuously to blowdown water, and even more preferably added continuously to blowdown water in order to synergistically exert the anticorrosive effect of the film-forming amine in combination with the polymer.

[0073] The amount (mg solid / L, hereinafter referred to as "mg / L") of the polymer (preferably a low molecular weight and / or (meth)acrylic acid-based polymer) used in the aqueous system is not particularly limited, but a suitable lower limit is preferably 0.5 mg / L or more, more preferably 1 mg / L or more, even more preferably 2 mg / L or more, more preferably 4 mg / L or more, more preferably 5 mg / L or more, more preferably more than 5 mg / L, more preferably 6 mg / L or more, more preferably 8 mg / L or more, more preferably 10 mg / L or more, more preferably 13 mg / L or more, more preferably 15 mg / L or more. Also, a suitable upper limit is not particularly limited, but from the viewpoint of a balance between reducing the amount of agent used and exhibiting an anticorrosion effect, it is preferably 100 mg / L or less, more preferably 50 mg / L or less, even more preferably 40 mg / L or less, more preferably 30 mg / L or less, more preferably 20 mg / L or less. The preferred numerical range is more preferably 3 to 30 mg / L, even more preferably 5 to 20 mg / L or 6 to 30 mg / L, and even more preferably 6 to 20 mg / L.

[0074] In a more preferred embodiment, the amount (mg solid / L) of the low-molecular-weight and / or (meth)acrylic acid-based polymer used in the aqueous system can be appropriately set to the above-mentioned preferred lower and upper limits of the amount of the polymer used, but a more preferred numerical range is more preferably 3 to 30 mg / L, even more preferably 5 to 20 mg / L or 6 to 30 mg / L, and even more preferably 6 to 20 mg / L. In an even more preferred embodiment, the amount (mg solid / L) of the sulfonic acid group-containing (meth)acrylic acid-based polymer used in the aqueous system can be any of the suitable lower and upper limits of the amount of the polymer used, but more preferred ranges are 3 to 30 mg / L, more preferably 5 to 20 mg / L or 6 to 30 mg / L, and even more preferably 6 to 20 mg / L. In an even more preferred embodiment, the amount (mg solid / L) of the AA / AMPS-based polymer and / or the AA / HAPS-based polymer used in the aqueous system can be any of the suitable lower and upper limits of the amount of the polymer used, but more preferred ranges are 3 to 30 mg / L, more preferably 5 to 20 mg / L or 6 to 30 mg / L, and even more preferably 6 to 20 mg / L.

[0075] In addition, as a more preferred aspect of this embodiment, the above-mentioned polymer is preferably used continuously or discontinuously in an aqueous system (preferably a cooling water system), and more preferably added to blowdown water.

[0076] <Suitable Use Proportions or Blending Ratios of the Phosphorus Compound, the Film-Forming Amine, and the Polymer>

[0077] The ratio of the film-forming amine and polymer used in the aqueous system or the blending ratio in the agent is not particularly limited, but may be determined by appropriately combining the amounts (mg / L) of each used in the aqueous system described above. The preferred range of the ratio or blending ratio is preferably 5-70:3-30 or 6-30, more preferably 10-50:5 or 6-20. Examples of such combinations include, but are not limited to, combinations of an aliphatic amine compound (e.g., an aliphatic diamine compound) with a low-molecular-weight (meth)acrylic acid monomer and a sulfonic acid group-containing monomer (e.g., the AA / AMPS-based polymer or the AA / HAPS-based polymer).

[0078] The ratio of the phosphorus compound and the film-forming amine to be used in the aqueous system or the compounding ratio in the agent is not particularly limited, but may be determined by appropriately combining the amounts (mg / L) of each compound used in the aqueous system described above. A suitable range for the ratio or compounding ratio is preferably 0.1-10:5-70, more preferably 1-5:10-50. Examples of such combinations include, but are not limited to, combinations of phosphonic acid compounds with aliphatic amine compounds (e.g., aliphatic diamine compounds).

[0079] The ratio of the phosphorus compound and the polymer to be used in the aqueous system or the blending ratio in the agent is not particularly limited, but may be determined by appropriately combining the amounts (mg / L) of each compound used in the aqueous system described above. A preferred range for the ratio or blending ratio is preferably 0.1 to 10 parts by weight of the phosphorus compound: 3 to 30 or 6 to 30 parts by weight of the polymer, and more preferably 1 to 5 parts by weight of the phosphorus compound: 5 or 6 to 20 parts by weight of the polymer. Suitable examples of such combinations include, but are not limited to, combinations of a phosphonic acid compound with a low-molecular-weight (meth)acrylic acid monomer and a sulfonic acid group-containing monomer (e.g., the AA / AMPS-based polymer, the AA / HAPS-based polymer, etc.).

[0080] The ratios of the phosphorus compound, the film-forming amine, and the polymer used or their blending ratios in the formulation are not particularly limited, but may be determined by appropriately combining the amounts (mg / L) of each compound used in the aqueous system described above. A preferred range for the ratios is 0.1-10:5-70:3-30 or 6-30, more preferably 1-5:10:10-50:5 or 6-20. Suitable examples of such combinations include, but are not limited to, combinations of a phosphonic acid compound, an aliphatic amine compound (e.g., an aliphatic diamine compound), a low-molecular-weight (meth)acrylic acid monomer, and a sulfonic acid group-containing monomer (e.g., the AA / AMPS polymer, the AA / HAPS polymer, etc.).

[0081] <Optional ingredients> In this embodiment, in addition to the above-described components (specifically, the film-forming amine, the polymer, and the phosphorus compound), optional components may be used in the aqueous system or contained in the agent as appropriate, as long as the effects of the present invention are not impaired. The optional components are not particularly limited, and may include, for example, one or more selected from the group consisting of a pH adjuster, an antifoaming agent, an anticorrosive other than the above-described components, a scale inhibitor, a bactericide, an algicide, and the like.

[0082] In this embodiment, in addition to the combined use of the film-forming amine and the polymer, or the combined use of these components and the phosphorus compound, it is preferable that a scale inhibitor other than these components be present in the aqueous system. Examples of the scale inhibitor include maleic acid-based polymers and salts thereof, and polyaspartic acid and salts thereof, and one or more selected from these can be used.

[0083] In addition to the combined use of the film-forming amine and the polymer, or the combined use of these components with the phosphorus compound, it is also preferable to use a slime control agent in the aqueous system. Examples of the slime control agent include, but are not limited to, hypochlorous acid and its salts, chlorine gas, hypobromous acid and its salts, stabilized chlorine, stabilized bromine, and organic disinfectants, and one or more selected from these may be used.

[0084] In this embodiment, in addition to the combined use of the film-forming amine and the polymer, or the combined use of these components with the phosphorus compound, it is preferable that a corrosion inhibitor (more preferably a corrosion-inhibiting metal compound) other than these components be present in the aqueous system. Note that the corrosion-inhibiting metal compound is a metal compound used for corrosion prevention, and the metal compound is a metal compound that can easily release heavy metal ions into water, and there are no particular limitations on the metal compound as long as it can exert this effect.

[0085] The "corrosion inhibitor other than these components" is not particularly limited, and examples thereof include corrosion inhibitor metal compounds such as zinc salts, tin salts, manganates, aluminum and aluminates; organic acid compounds, polyaspartic acid and its salts, polyitaconic acid and its salts, and amino acid compounds. One or more selected from the group consisting of these can be used. Among these, corrosion inhibitor metal compounds are more preferred, and among these corrosion inhibitor metal compounds, zinc salts and / or tin salts are preferred, with zinc salts being even more preferred. Note that when a phosphate compound is selected as the "phosphorus compound," it is desirable to exclude the phosphate compound from the "corrosion inhibitor other than these components." However, when a phosphonate compound is selected, the phosphate compound may be selected from the "corrosion inhibitor other than these components." Further suitable "corrosion inhibitors other than these components" that can be used in combination include one or more selected from phosphate compounds (orthophosphoric acid, PBTC, hexane metaphosphate, etc.), zinc salts (zinc chloride, zinc sulfate, etc.), and copper corrosion inhibitors (benzotriazole / tolyltriazole, etc.), which are commonly used in cooling water systems.

[0086] The amount (mg soil / L, hereinafter referred to as "mg / L") of the "anticorrosive agent other than these components" used is not particularly limited, but a suitable lower limit is preferably 0.1 mg / L or more, more preferably 0.5 mg / L or more, and a suitable upper limit is preferably 5 mg / L or less, more preferably 4 mg / L or less, even more preferably 3 mg / L or less, and more preferably 2 mg / L or less. By adding a suitable amount of the anticorrosive agent (C) to the aqueous system, it is possible to achieve a corrosion inhibitory effect equal to or greater than the combined effect of the copolymer (A) and the maleic acid-based polymer (B). Thus, when obtaining an anticorrosive effect equivalent to that of the components (A) and (B), adding the component (C) also makes it possible to further reduce the amounts of the components (A) and (B) added.

[0087] 1-5.Metal corrosion prevention methods for water-based systems As described above, the aqueous metal anticorrosion treatment method of this embodiment can use a combination of the film-forming amine, the polymer, and the phosphorus compound, and it is preferable that these three components are present in the aqueous system at the same time. Furthermore, in this embodiment, each of these components may be added to the aqueous system continuously or intermittently. In this embodiment, each of these components may be added to the aqueous system at the same time or at different times. The aqueous system may be equipped with one or more chemical injection devices for adding chemicals (components) to the aqueous system. The chemical injection devices may add individual components, a mixture of two components and another component, or a mixture of three components at the same time or at different times so that these three components are present in the aqueous system at the same time. In one preferred example of this embodiment, the film-forming amine is present in the aqueous system as an online scale remover, and the three components are preferably adjusted to be present in the aqueous system at the same time. In this embodiment, the locations where these components are mixed include, but are not limited to, a channel (e.g., a circulating water channel) or inside a pipe in the water system, a tank (e.g., a pit) such as a chemical storage tank or a chemical mixing tank that may be provided in the water system, etc. The water system may also be appropriately equipped with a measuring device capable of measuring the concentration of each chemical (concentration of each component) in the water system, and a measuring device capable of measuring the water quality of the water system. In this embodiment, these measurement results may be transmitted to a control unit, etc., and the control unit, etc. may control or manage the method of this embodiment or its steps, operations, etc.

[0088] As described above, in the aqueous metal corrosion protection method of this embodiment, it is preferable that the film-forming amine and the polymer are used in combination, or the film-forming amine, the polymer, and the phosphorus compound are used in combination in a predetermined mass use ratio or mass content ratio in the aqueous system.

[0089] In this embodiment, the film-forming amine and the polymer in combination, or the film-forming amine and the polymer and the phosphorus compound in combination, can be added to the aqueous system as a one-part formulation or as a multi-part formulation (e.g., a combination product). In another aspect of the present embodiment, a water treatment agent containing at least one of the phosphorus compound, the film-forming amine, and the polymer is added to an aqueous system, thereby causing the phosphorus compound, the film-forming amine, and the polymer to be present in the aqueous system, thereby providing a corrosion prevention method for an aqueous system.

[0090] Furthermore, the film-forming amine and the polymer may be added in combination, or the film-forming amine, the polymer, and the phosphorus compound may be added in combination to the aqueous system at the same time or at different times so that these three components are present in the aqueous system. The addition of these three components may be continuous or intermittent.

[0091] In a more preferred embodiment of the present embodiment, there can be provided a method for metal corrosion prevention treatment of an aqueous system using the following (i) metal corrosion prevention agent, (ii) water treatment agent, or (iii) water treatment agent for metal corrosion prevention or combination product for water treatment agent. In this specification, a combination product may also be referred to as a product set or a kit product. (i) A metal corrosion inhibitor comprising a phosphorus compound, a film-forming amine, and a polymer. (ii) a water treatment agent containing a film-forming amine and / or a polymer; The water treatment agent is used in combination with the film-forming amine and the polymer in an aqueous system to enhance the metal corrosion prevention provided by the phosphorus compound. (iii) A water treatment agent containing at least one of a phosphorus compound, a film-forming amine, or a polymer; A water treatment agent for metal corrosion prevention, which is used in combination with a phosphorus compound, a film-forming amine, and a polymer in an aqueous system when used for metal corrosion prevention in an aqueous system, may be a water treatment agent combination product composed of at least one, two, or three water treatment agents selected from a first water treatment agent containing the phosphorus compound, a second water treatment agent containing the film-forming amine, and a third water treatment agent containing the polymer. As a more preferred aspect of the present embodiment, when the above-mentioned metal corrosion inhibitor, the water treatment agent, the third water treatment agent, etc. are used in an aqueous system, it is preferable that they contain or be configured so that the polymer (preferably a copolymer of the (meth)acrylic acid monomer and the sulfonic acid group-containing monomer) is added in an amount of 6 mg / L or more.

[0092] The water system to which this embodiment is applied is not particularly limited, and examples thereof include cooling water systems, RO water systems, water systems in paper pulp processes, scrubber water systems, etc. In this embodiment, the corrosion prevention effect is sufficiently exhibited as long as the water quality is that of a general water system (preferably a cooling water system).

[0093] The acid consumption (pH 8.3) of the aqueous system is not particularly limited as a water quality condition. From the viewpoint of better corrosion prevention effect, the upper limit is preferably 1000 mg CaCO3 / L or less, more preferably 500 mg CaCO3 / L or less, and even more preferably 300 mg CaCO3 / L or less. The lower limit is preferably 10 mg CaCO3 / L or more, more preferably 25 mg CaCO3 / L or more, even more preferably 50 mg CaCO3 / L or more, and even more preferably 50, 75, or 100 mg CaCO3 / L or more. The preferred range is more preferably 25 to 500 mg CaCO3 / L, and even more preferably 100 to 300 mg CaCO3 / L. The acid consumption (pH 8.3) can be determined in accordance with JIS K0101 Industrial Water Testing Method. The acid consumption rate is the amount of alkaline components (bicarbonate, carbonate, hydroxide, etc.) contained in the water converted into the equivalent calcium carbonate concentration (unit: mgCaCO3 / L).

[0094] As a condition for the water quality of the aqueous system, calcium hardness is not particularly limited, and from the viewpoint of a better corrosion prevention effect, a suitable upper limit is not particularly limited, but is, for example, 1000 mgCaCO3 / L or less, preferably 500 mgCaCO3 / L or less, more preferably 300 mgCaCO3 / L or less, and a suitable lower limit is preferably 5 mgCaCO3 / L or more, even more preferably 10 mgCaCO3 / L or more, more preferably 25 mgCaCO3 / L or more, more preferably 50, 75, or 100 mgCaCO3 / L or more, and the suitable numerical range is preferably 25 to 300 mgCaCO3 / L. Calcium hardness can be determined in accordance with JIS K0101 Industrial Water Testing Method.

[0095] As for the water quality conditions of the water system, the pH of the water system is not particularly limited, but from the viewpoint of a better anticorrosion effect, it is preferably 6 to 11, more preferably 6.5 to 10, and even more preferably 7 to 9. Furthermore, the water temperature of the water system is not particularly limited, but from the viewpoint of a better anticorrosion effect, it is preferably 0 to 100°C, more preferably 5 to 80°C, and even more preferably 10 to 60°C.

[0096] A preferred aspect of this embodiment is that it is applied to a water system in which metal materials that are susceptible to corrosion by water are used in various locations (for example, heat exchangers, piping, etc.), more preferably to a cooling water system, and even more preferably to a circulating cooling water system. According to this embodiment, the corrosion prevention effect of the corrosion prevention treatment method of the present invention can be fully exerted by this more preferred application.

[0097] The method of this embodiment can also be realized by a control unit including a CPU or the like in a device (e.g., a computer, PLC, server, cloud service, etc.) for managing the above-mentioned metal anticorrosion treatment or the cooling water system described below. The method of this embodiment can also be stored as a program in hardware resources including a recording medium (non-volatile memory (e.g., USB memory), SSD, HDD, CD, DVD, Blu-ray Disc, etc.) and realized by the control unit. The recording medium is preferably a computer-readable recording medium. It is also possible to provide a device including the control unit or the system, such as a metal anticorrosion treatment system in which the control unit controls the addition of chemicals to a water system. The management device includes, as computer components, at least a CPU, an input unit such as a keyboard, a communication unit such as a network, a display unit such as a display, a storage unit such as a HDD, ROM, RAM, etc., from which one or more components can be selected. Among these, it is preferable that the device be equipped with RAM, a storage unit, a display unit, and an input unit, and the selected components are connected, for example, by a bus as a data transmission path.

[0098] <Cooling water system> The cooling water system to be applied to this embodiment is not particularly limited, but is preferably a system through which cooling water used for operating a heat exchanger or the like is passed in air conditioning equipment for buildings, local facilities, etc., plants, etc. The cooling water system may be any of a pass-through type, an open circulation type, or a closed circulation type.

[0099] In this embodiment, by applying it to a circulating cooling water system, an excellent anticorrosion effect can be exhibited in the circulating cooling water system. The circulating cooling water system is not particularly limited, and is preferably a water system equipped with a cooling tower installed in an air conditioning system, a petrochemical complex, a general factory, etc. The circulating cooling water system is preferably configured to indirectly cool a heat source generated in the air conditioning system, the general factory, etc., and may be a general water system configured to include a heat exchanger, a circulating water channel, and a cooling tower.

[0100] The type of circulating cooling water system is not particularly limited, and may be either an open circulating cooling water system or a closed circulating cooling water system. An open circulating cooling water system is preferably configured to allow cooling water to circulate in an open manner, and a closed circulating cooling water system is preferably configured to allow cooling water to circulate in a closed manner.

[0101] Furthermore, the metal corrosion prevention treatment method for a cooling water system of this embodiment (more specifically, the metal corrosion prevention treatment method for metal components in a cooling water system) preferably includes at least the step of adding the film-forming amine, the polymer, and the phosphorus compound to the cooling water system and contacting them with the metal components. The film-forming amine and the polymer, or the film-forming amine, the polymer, and the phosphorus compound, may be added as a one-component metal corrosion prevention treatment agent or as a multi-component metal corrosion prevention treatment combination product. The film-forming amine, the polymer, and the phosphorus compound may be added to the cooling water system simultaneously or separately. It is preferable that these three components are added so that they are present together in the water system. The period during which these three components are present together is not particularly limited and may be continuous or intermittent. For example, the phosphorus compound, the polymer (first polymer), and the film-forming amine may be added to the cooling water system in this order. Furthermore, after mixing these, the polymer (second polymer) may be further added, and the first polymer and the second polymer may be the same or different polymers. The amount of the second polymer added is preferably 0.5 to 2 times or more, and more preferably about 1.5 to 2.5 times, the amount of the first polymer added. When the first and second polymers are the same polymer, the total amount used of the first and second polymers may be referred to as the total amount used or total amount added. The location of addition of the chemicals is not particularly limited and may be any location in the cooling water system, such as a blower, a sprinkler, a pit, a makeup water supply, a chemical injection means, a circulating water channel, a transfer pump, a heat exchanger, etc., and preferably a makeup water supply, a chemical injection means, a circulating water channel, a transfer pump, etc., and the chemicals may be added at one or more locations selected from these. By adding these three components so that they are present at any location in the water system, a better corrosion prevention effect can be obtained for metal materials in contact with the water downstream. Furthermore, when all or part of the water system is circulated, the circulation of the water system mixes these three components, thereby achieving a better corrosion prevention effect for metal materials in contact with the water in the water system.

[0102] As described above, the metal anticorrosion treatment method of this embodiment can impart an excellent anticorrosion effect to metal members that come into contact with water.

[0103] A metal anticorrosion treatment method for an open circulating cooling water system 1 as an example of this embodiment will be described with reference to FIG. 1, but this embodiment is not limited thereto. In the open-circulating cooling water system 1, water containing the film-forming amine, the polymer, and the phosphorus compound is transferred from the pit 15 to the heat exchanger 30 via the circulation water line 20 by the transfer pump 21, passes through the heat exchanger 30, and returns to the open-type cooling tower 10 via the circulation water line 20. Within the cooling tower 10, the water containing these components passes through the water spray means 12 and the filler region 13, is stored in the pit 15, and is then transferred again by the pump 21 to the circulation water line 20. In this embodiment, the corrosion prevention effect for the cooling water system can be maintained during this circulation. This circulation allows the film-forming amine and the polymer, or the film-forming amine, the polymer, and the phosphorus compound present in the water in the water system, to come into contact with metal members, thereby exerting a corrosion prevention effect on the metal members. It is preferable to add the film-forming amine, the polymer, and the phosphorus compound to the aqueous system using a chemical injection device capable of adding each of these components or a mixture of these two or three components, so that these three components are present together in the aqueous system. Furthermore, the amount of each component added may be adjusted so that each component is within a predetermined concentration range in the aqueous system.

[0104] The film-forming amine and the polymer, or the film-forming amine, the polymer, and the phosphorus compound, are transported to the pit 15 simultaneously or separately by one or more chemical injection means 17. The two may be mixed in the piping during transport, or they may be mixed in the pit 15. The chemical injection means 17 may be single or multiple. For example, multiple separate chemical injection means may be provided for the film-forming amine, the polymer, and the phosphorus compound, respectively. Alternatively, a single chemical injection means may be provided for adding a one-component chemical containing these components to the aqueous system or for mixing these components. Water shortage due to evaporation or other reasons is supplied to the pit 15 by a makeup water supply means 16 as needed. The flow path for supplying this makeup water to the pit 15 may be configured to allow the addition of one or more chemicals from the chemical injection means 17. The air for cooling is exhausted from the outside by the ventilation means 11, via louvers 18, 13, 12, and then discharged from 11.

[0105] In the explanation of the examples of the aqueous metal corrosion prevention treatment method according to the present embodiment described above, the explanations of the phosphorus compound, the film-forming amine, the polymer, their use concentrations and use ratios, and the technical features, configurations, definitions, terms, treatment methods, and various means of the aqueous metal corrosion prevention treatment, aqueous metal corrosion prevention treatment management, aqueous metal corrosion prevention system, and aqueous metal corrosion prevention treatment method, which are the same as or overlap with the contents described below (for example, "2." to "3."), will be omitted as appropriate, but the explanations in "1." to "3." etc. apply to any of the embodiments and can be adopted as appropriate for each embodiment.

[0106] 2. Metal corrosion inhibitors according to this embodiment In describing examples of the metal corrosion inhibitor, water treatment agent, combination product for a water treatment agent, etc. according to the present invention, the same or overlapping descriptions as those described above (for example, "1.") and below (for example, "3."), such as the phosphorus compound, the film-forming amine, the polymer, their use concentrations and use ratios, and each technical feature, configuration, definition, terminology, treatment method, various means, etc. of aqueous metal corrosion inhibitors, aqueous metal corrosion inhibitor management, aqueous metal corrosion inhibitor systems, aqueous metal corrosion inhibitor methods, etc., will be omitted as appropriate, but the descriptions in "1." to "3.", etc., apply to any of the embodiments and can be adopted as appropriate for each embodiment.

[0107] The use of the phosphorus compound, the film-forming amine, and the polymer in an aqueous system can exhibit excellent corrosion prevention effects. That is, the combination of the phosphorus compound, the film-forming amine, and the polymer can be contained as an active ingredient in an aqueous corrosion prevention composition, an aqueous metal corrosion inhibitor, a water treatment agent, a drug, or the like, or can be used in such a composition. In this embodiment, the composition may be an agent, and the agent may be a composition. Furthermore, the phosphorus compound, the film-forming amine, and the polymer used in this embodiment are preferably compositions or agents configured so that each component is added to the aqueous system in a predetermined amount or more, or are preferably used so that each component is added to the aqueous system in a predetermined amount or more. Furthermore, the phosphorus compound, the film-forming amine, and the polymer, or a mixture thereof, can be used to produce the aqueous metal corrosion inhibitor of this embodiment. The present embodiment can also provide the phosphorus compound, the film-forming amine, and the polymer, or a mixture thereof, or use thereof for metal corrosion prevention in an aqueous system, etc. The present embodiment can also provide the phosphorus compound, the film-forming amine, and the polymer, or a mixture thereof, for use in metal corrosion prevention in an aqueous system, etc. The present embodiment can also provide a method for preventing metal corrosion in an aqueous system or a method for metal corrosion prevention treatment in an aqueous system using the phosphorus compound, the film-forming amine, and the polymer or a mixture thereof, or an aqueous metal corrosion inhibitor, water treatment agent, a combination product for a water treatment agent, or the like.

[0108] In addition, as another aspect of the present embodiment, there can be provided a metal corrosion inhibitor comprising a phosphorus compound, a film-forming amine, and a polymer.

[0109] Furthermore, as another aspect of the present embodiment, there can be provided a phosphorus compound, a film-forming amine, and a polymer, or use thereof, for use in metal corrosion protection or as a metal corrosion inhibitor, or a composition containing these three components, or use thereof.

[0110] In addition, as another aspect of the present embodiment, there can be provided a phosphorus compound, a film-forming amine, and a polymer, or use thereof, for producing or to be used for producing a metal corrosion inhibitor, or a composition containing these three components, or use thereof.

[0111] In another aspect of this embodiment, there is provided a water treatment agent comprising at least one of a phosphorus compound, a film-forming amine, or a polymer, A water treatment agent for metal corrosion prevention can also be provided, which is used in combination with a phosphorus compound, a film-forming amine, and a polymer for use in a water system for metal corrosion prevention. The water treatment agent may be a combination product for water treatment that is composed of at least one, two, or three water treatment agents selected from a first water treatment agent containing the phosphorus compound, a second water treatment agent containing the film-forming amine, and a third water treatment agent containing the polymer.

[0112] Another aspect of this embodiment is a water treatment agent containing a film-forming amine and / or a polymer, When used in an aqueous system, the film-forming amine and the polymer can be used in combination to provide a water treatment agent that is used to enhance the metal corrosion prevention provided by the phosphorus compound.

[0113] In addition, as another aspect of the present embodiment, there can be provided a phosphorus compound, a film-forming amine, and a polymer, or use thereof, for producing the agent, or for use in producing the agent, or for use in producing the agent.

[0114] In addition, as another aspect of the present embodiment, there can be provided a corrosion prevention method for a water system for inhibiting corrosion of a metal in contact with water, using the agent.

[0115] The polymer is preferably a low-molecular-weight polymer, more preferably a low-molecular-weight polymer with a weight-average molecular weight of 500 to 100,000. The polymer is preferably a water-soluble organic polymer, more preferably a copolymer, more preferably a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer, and even more preferably a copolymer of (a) a (meth)acrylic acid monomer and (b) a monomer containing (i) an amide group and a sulfonic acid group, or (ii) a hydroxyl group and a sulfonic acid group. The polymer is preferably used in a composition containing the polymer so that the amount added to an aqueous system is 6 mg / L or more, or in a composition containing the polymer so that the amount added to an aqueous system is 6 mg / L or more.

[0116] The polymer is preferably a (meth)acrylic acid-based polymer containing a sulfonic acid group, and the molar ratio of the (meth)acrylic acid monomer to the sulfonic acid monomer in the polymer is preferably 60 to 95:40 to 5. Of the (meth)acrylic acid-based polymers, AA / AMPS-based polymers and / or AA / HAPS-based polymers are preferred.

[0117] The phosphorus compound is preferably a phosphonic acid compound. The film-forming amine is preferably a long-chain aliphatic amine compound, and among these, a long-chain aliphatic diamine compound is preferred.

[0118] The ratio of the film-forming amine and the polymer used in the aqueous system or the blending ratio in the pharmaceutical agent is preferably 5-70:3-30. The ratio of the phosphorus compound and the film-forming amine used in the aqueous system or the compounding ratio in the agent is preferably 0.1-10:5-70 of the phosphorus compound:film-forming amine.

[0119] The ratio of the phosphorus compound and the polymer used in the aqueous system or the compounding ratio in the pharmaceutical agent is preferably 0.1-10:3-30 or 6-30:30 of the phosphorus compound:polymer.

[0120] The proportions of the phosphorus compound, the film-forming amine and the polymer used or the compounding ratio in the agent are preferably 0.1-10:5-70:3-30 or 6-30:5-70:30 of the film-forming amine and the polymer.

[0121] 3. The technology may also employ the following technical features, configurations, or other aspects: 〔1〕 A corrosion prevention method for water systems to suppress corrosion of metals in contact with the water system, A corrosion prevention method for an aqueous system, comprising using a phosphorus compound, a film-forming amine, and a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer in the aqueous system. The molecular weight of the copolymer is preferably a weight average molecular weight of 500 to 100,000. The monomer ratio of the (meth)acrylic acid monomer to the sulfonic acid group-containing monomer in the copolymer is preferably 60 to 95:40 to 5. Preferably, the amount of the copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer used is more than 5 mg / L. 〔2〕 The method according to [1] above, wherein the copolymer is a copolymer obtained from (a) a (meth)acrylic acid monomer and (b) (i) an amide group- and sulfonic acid group-containing monomer and / or (ii) a hydroxy group- and sulfonic acid group-containing monomer, wherein the monomer ratio of the (meth)acrylic acid monomer to the amide group- and sulfonic acid group-containing monomer in the copolymer is preferably 60-95:40-5. 〔3〕 The method according to [1] or [2], wherein the film-forming amine is an aliphatic amine compound. The aliphatic amine compound is preferably a long-chain aliphatic amine compound. The aliphatic amine compound is preferably an aliphatic monoamine compound and / or an aliphatic diamine compound, and more preferably an aliphatic diamine compound. 〔4〕 The method according to any one of [1] to [3] above, wherein the phosphorus compound is a phosphoric acid compound and / or a phosphonic acid compound, more preferably a phosphonic acid compound. A mixture containing the phosphorus compound and a corrosion inhibitor other than the phosphorus compound (for example, a zinc salt and / or a copper corrosion inhibitor) may be used. 〔5〕 The method according to any one of [1] to [4] above, wherein a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer is used in combination with the film-forming amine in the aqueous system. 6. The method according to any one of [1] to [5] above, wherein the water system is a cooling water system. The cooling water system is preferably an open circulation system or a closed circulation system, and more preferably an open circulation system.

[0122] 7. A metal corrosion inhibitor comprising a phosphorus compound, a film-forming amine, and a polymer. The polymer is preferably a low-molecular-weight polymer, more preferably a low-molecular-weight polymer with a weight-average molecular weight of 500 to 100,000. The polymer is preferably a water-soluble organic polymer, more preferably a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer. The polymer is preferably the copolymer described in any one of [1] to [6] above. The phosphorus compound and / or the film-forming amine are preferably the compounds described in [3] and / or [4] above. The metal corrosion inhibitor is preferably configured so that the polymer can be used in an amount exceeding 5 mg / L, or the metal corrosion inhibitor is preferably used so that the polymer can be added in an amount exceeding 5 mg / L. 8. A phosphorus compound, a film-forming amine, and a polymer, or their use, or a composition containing these three components, or their use, for use in metal corrosion prevention or as a metal corrosion inhibitor. The polymer is preferably the polymer described in [7] above or the copolymer described in any one of [1] to [6] above. The phosphorus compound and / or the film-forming amine is preferably the compound described in [3] and / or [4] above. The polymer is preferably used in an aqueous system so that the concentration exceeds 5 mg / L, or the composition is preferably configured so that the polymer can be used at an addition amount of more than 5 mg / L. 9. In the production of a metal corrosion inhibitor or the like, use of a phosphorus compound, a film-forming amine, and a polymer, or one, two, or three of these, for producing or used in producing a metal corrosion inhibitor or the like, or a composition containing these three components, or use thereof. The polymer is preferably the polymer described in [7] above or the copolymer described in any one of [1] to [6] above. The phosphorus compound and / or the film-forming amine is preferably the compound described in [3] and / or [4] above. The polymer is preferably used so that the concentration exceeds 5 mg / L in an aqueous system, or the composition is preferably configured so that the polymer can be used at an addition amount of more than 5 mg / L.

[0123] 10. A water treatment agent for metal corrosion prevention contains at least one of a phosphorus compound, a film-forming amine, and a polymer. When used for metal corrosion prevention in an aqueous system, the phosphorus compound, the film-forming amine, and the polymer are used in combination with the aqueous system or are intended for use. The water treatment agent may be a combination product composed of at least one, two, or three water treatment agents selected from a first water treatment agent containing the phosphorus compound, a second water treatment agent containing the film-forming amine, and a third water treatment agent containing the polymer. The polymer is preferably the polymer described in [7] above or the copolymer described in any one of [1] to [6] above. The phosphorus compound and / or the film-forming amine is preferably the compound described in [3] and / or [4] above. The polymer is preferably used so that the concentration of the polymer exceeds 5 mg / L in the aqueous system, or the water treatment agent is preferably configured to be usable with an added amount of the polymer exceeding 5 mg / L.

[0124] 11. A water treatment agent containing a film-forming amine and / or a polymer, A water treatment agent used in an aqueous system in combination with the film-forming amine and the polymer to enhance metal corrosion protection by a phosphorus compound. The polymer is preferably the polymer described in [7] above or the copolymer described in any one of [1] to [6] above. The phosphorus compound and / or the film-forming amine are preferably the compounds described in [3] and / or [4] above.

[0125] 12 A phosphorus compound, a film-forming amine, and a polymer, or use thereof, for producing, or for use in producing, the agent according to any one of [7] to

[11] above. 13 A method for preventing corrosion of a water system by using the component or agent described in [7] to

[12] above, for suppressing corrosion of a metal in contact with water, a method for enhancing metal corrosion prevention by a phosphorus compound, or a method for reducing the amount of phosphorus used in a water system. [Example]

[0126] The following examples and comparative examples will be used to explain the embodiments of the present invention. Note that the examples described below are representative examples of the present invention, and the scope of the present invention should not be construed as being narrow.

[0127] [Test Example 1] <Experimental conditions> Pure water was placed in a 1 L glass beaker, and sodium bicarbonate solution and calcium chloride solution were added to adjust the pH to 8.4, acid consumption to 150 mg CaCO3 / L, and calcium hardness to 150 mg CaCO3 / L. As a corrosion inhibitor, 4 mg PO4 / L of HEDP (hydroxyethylidenediphosphonic acid) was added, and as a scale inhibitor, 5 mg solid / L of AA / AMPS polymer (monomer ratio (mol %) 80:20, average molecular weight 20,000) was added. After adding 50 mg / L of film-forming amine (alkylpropanediamine (alkyl carbon number 16-18)), various polymers were added at 10 mg solid / L.

[0128] Tables 1 to 3 show the combinations of phosphorus compounds, film-forming amines, and polymer components in Test Example 1 (Reference Examples 1-1 to 1-6 and Examples 1-7 to 1-10), Test Example 2 (Reference Example 2-1 and Examples 2-2 to 2-4), and Test Example 3 (Reference Examples 3-1 to 3-3 and Examples 3-4 to 3-5). As reference examples, experiments were also carried out without adding HEDP or without adding film-forming amine. The polymers used were AA / AMPS-based polymers, AA / HAPS-based polymers, and polymaleic acid-based polymers with weight-average molecular weights of 400 to 110,000, as shown in Tables 1 and 2. The molecular weights of the polymers are weight-average molecular weights, and are values ​​determined by GPC analysis (standard substance: PAANA (sodium polyacrylate) manufactured by PSS).

[0129] <Corrosion rate test (mg / dm 2 / day)> The test piece 101 was an SPCC (15 mm x 30 mm) test piece, which was immersed in test water 102 and tested at a water temperature of 40°C for 3 days at 150 rpm using a rotary corrosion tester 100 (Fig. 2) equipped with a stirrer 103 for stirring the test water with a stirrer and a temperature control device 104 for heating and cooling the test water 102. The material of SPCC (Steel Plate Cold Commercial: a type of cold-rolled steel plate) is a low-carbon steel with a carbon content of 0.15% or less. After the test, the test piece was taken out and derusted with hydrochloric acid, and the corrosion weight was measured. The corrosion rate (mg / dm 2 / day) was calculated. In addition, to verify the effect of different corrosion inhibitors, an evaluation was also conducted using PBTC (4 mg PO4 / L) instead of HEDP (4 mg PO4 / L).

[0130] [Table 1]

[0131] [Table 2]

[0132] [Table 3]

[0133] <Results / Discussion> Tables 1 and 2 show the results when HEDP was used as a corrosion inhibitor, and Table 3 shows the results when PBTC was used. Regardless of the type of corrosion inhibitor, the use of AA / AMPS or AA / HAPS with a molecular weight of 4,000 to 20,000 significantly enhanced the corrosion prevention effect, prolonging the life of the metal during the addition of the film-forming amine. Furthermore, in terms of corrosion rate trends, the AA / AMPS ratio and AA / HAPS ratio (mol %) of AA / AMPS-based polymers and AA / HAPS-based polymers are considered to be preferably 1 to 95:99 to 5, more preferably 60 to 95:40 to 5, and even more preferably 75 to 90:25 to 10. This confirmed that the presence of three components in an aqueous system - a film-forming amine, a (meth)acrylic acid-based polymer containing low molecular weight sulfur atoms, and a phosphonic acid compound - significantly enhances the corrosion protection effect on metal materials in contact with water. Furthermore, the combined use of a film-forming amine and a (meth)acrylic acid-based polymer containing low molecular weight sulfur atoms produced a synergistic effect in the corrosion inhibition of metal materials in contact with water. Furthermore, it is preferable to use the polymer at a concentration of more than 5 mg / L in the aqueous system.

[0134] In this specification, for convenience, descriptions may be given using numbers or letters such as "first, second, third...," "A, B, C...," "primary, secondary, tertiary...," etc. However, this does not limit the interpretation of the present invention in a narrow sense, and the order may be changed as desired. A combination product may also be used in combination. In addition, in this specification, for example, "to manage" or the like may be expressed as a method, process, means, or step, and these terms may be interchanged as appropriate. For example, "step" may be expressed as "to do," method, process, or means, etc.; "process" may be expressed as "to do," method, step, or means, etc.; and "means" may be expressed as "to do," method, process, or step, etc. Furthermore, in this specification, a "system" may be a mechanism, device, means, or part; a "mechanism" may be a system, device, means, or part; a "device" may be a system, mechanism, means, or part; a "means" may be a mechanism, system, device, or part; and a "part" may be a mechanism, means, device, or system, or a mechanism, means, or device that is provided for these. [Explanation of symbols]

[0135] 1 open circulating cooling water system, 10 open cooling tower, 11 ventilation means, 12 water spray means, 13 filling material area, 14 space, 15 pit, 16 makeup water supply means, 17 chemical injection means, 18 louver, 20 circulating water channel, 21 transfer pump, 30 heat exchanger

Claims

1. A corrosion prevention method for water systems to suppress corrosion of metals in contact with the water system, The aqueous system contains a phosphorus compound, a film-forming amine, and more than 5 mg / L of a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer having a weight average molecular weight of 500 to 100,000. Corrosion prevention methods for water systems.

2. 2. The method according to claim 1, wherein the copolymer is a copolymer of a (meth)acrylic acid monomer and a monomer containing an amide group and a sulfonic acid group or a hydroxy group and a sulfonic acid group.

3. 3. The method of claim 1, wherein the film-forming amine is an aliphatic amine compound.

4. The method according to claim 1 or 2, wherein the phosphorus compound is a phosphonic acid compound.

5. 3. The method according to claim 1, wherein the film-forming amine is used in the aqueous system in combination with the copolymer of the (meth)acrylic acid monomer and the sulfonic acid group-containing monomer.

6. 3. The method of claim 1 or 2, wherein the water system is a cooling water system.

7. a phosphorus compound, a film-forming amine, and a low molecular weight polymer having a weight average molecular weight of 500 to 100,000; The polymer is included for use at dosages greater than 5 mg / L. Metal corrosion inhibitor.

8. A water treatment agent containing at least one of a phosphorus compound, a film-forming amine, or a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer having a weight average molecular weight of 500 to 100,000, When used for metal corrosion protection in an aqueous system, the phosphorus compound, the film-forming amine, and the copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer are used in combination with the aqueous system, The copolymer is included for use at a dosage of more than 5 mg / L. Water treatment agent for metal corrosion prevention.

9. A water treatment agent containing a film-forming amine and / or a copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer, the copolymer having a weight average molecular weight of 500 to 100,000, When used in an aqueous system, the film-forming amine and the copolymer of a (meth)acrylic acid monomer and a sulfonic acid group-containing monomer are used in combination to strengthen the metal corrosion prevention effect of the phosphorus compound, The copolymer is included for use at a dosage of more than 5 mg / L. Water treatment agent.

10. 10. A method for preventing corrosion in aqueous systems, comprising using the agent according to claim 7, 8 or 9 to inhibit corrosion of metals in contact with water.

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