JP2012041606A - Corrosion and scale preventing liquid composition and method for preventing corrosion and scale - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable and economical aqueous corrosion and scale preventing liquid composition and a method for preventing corrosion and scale, for simultaneously preventing corrosion and scale of an iron-based metal and a copper-based metal in a water circulation system where the iron-based metal and the copper-based metal coexist together.SOLUTION: In the corrosion and scale preventing liquid composition, which is prepared by adding an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing: (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, and zinc phosphate; (2) benzotriazoles; (3) one or more selected from organic phosphonic acid, phosphino polycarboxylic acid, phosphono carboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer, and sulfonic group-containing polymer and adjusting pH to 0.0-2.5, an equivalent ratio of the total quantity of the sulfuric acid and the nitric acid to the total quantity of zinc and the alkali metal is 0.7 and more and less than 1.0. The method for preventing corrosion and scale of the iron-based metal and the copper-based metal in an aqueous system by using the corrosion and scale preventing liquid composition is also provided.

Description

  The present invention relates to an aqueous corrosion and scale prevention liquid composition capable of simultaneously preventing corrosion and scale of an iron-based metal and a copper-based metal in an aqueous system in which an iron-based metal and a copper-based metal coexist, and corrosion using the same. It relates to a prevention method.

  Aqueous systems such as a circulating cooling water system, a circulating cold / hot water system, and a circulating heating water system are composed of pipes, valves, circulating pumps, heat exchangers, etc., and iron-based metals and copper-based metals may be mixed as these materials. Many.

  Since ferrous metals are inexpensive, they are widely used as materials for pipes, valves, circulation pumps, heat exchanger tubes and fuselage of heat exchangers in water circulation systems. On the other hand, copper-based metals such as pure copper, phosphorus deoxidized copper, tough pitch copper, brass, aluminum brass, admiralty brass, naval brass, bronze, and cupronickel have good thermal conductivity and relatively good corrosion resistance. Widely used in heat transfer tube materials and tube sheets for heat exchangers such as condensers and condensers in plants.

  In this way, copper-based metals have better corrosion resistance than iron-based metals, but when chlorinated or brominated fungicides are added to prevent microbial damage in water, Agents and bromine-based disinfectants are highly corrosive to copper-based metals, and are susceptible to pitting corrosion and stress corrosion cracking.

  In addition, in water systems where iron-based metals and copper-based metals coexist, galvanic corrosion that facilitates corrosion of iron-based metals is likely to occur due to the precipitation of copper ions eluted by the corrosion of copper-based metals on the surface of iron-based metals. .

  For the above reasons, in an aqueous system in which iron-based metal and copper-based metal coexist, it is preferable to use a corrosion inhibitor for copper-based metal together with a corrosion inhibitor for iron-based metal.

  Since iron-based metals are highly corrosive in water, corrosion inhibitors for iron-based metals are generally added. Corrosion inhibitors containing zinc salts are used because of their high anti-corrosion effect (Patent Documents) 1).

  It is known as a prior art that triazoles such as benzotriazole and tolyltriazole (methylbenzotriazole) are effective in suppressing corrosion of copper-based metal and corrosion of iron-based metal (galvanic corrosion) by copper ions ( Patent Document 2).

  Therefore, it is desirable to add triazoles such as benzotriazole and tolyltriazole (methylbenzotriazole) together with organic phosphoric acids and zinc salts to prevent corrosion in aqueous systems where iron-based metals and copper-based metals coexist. Corrosion and scale prevention compositions comprising phosphonic acid compounds, azole compounds including triazoles, and zinc salts have been proposed (see Patent Document 3), and zinc sulfate, zinc chloride, alkali metal-zinc phosphate as zinc salts have been proposed. Salt glass, crystalline antkari metal-polyphosphate zinc salt and the like are disclosed. However, since the organic phosphonic acid compound and the azole compound and the above zinc salt have poor compatibility, a stable one-component composition could not be obtained.

JP 62-96683 A JP-A-1-299699 Japanese Patent Publication No. 44-28973

  In order to constantly suppress corrosion of metals in water, it is necessary to have a corrosion inhibitor having a certain concentration or more in water. To that end, it is necessary to add a corrosion inhibitor quantitatively to the water system, but it is difficult to add the corrosion inhibitor quantitatively to water if it is in a solid state. It is preferable to add with a metering pump or the like.

  In aqueous systems where iron-based metals and copper-based metals coexist, it is necessary to use a corrosion inhibitor for copper-based metals containing triazoles together with a corrosion inhibitor for iron-based metals containing zinc salts. Therefore, there has been a demand for a corrosion inhibitor in liquid form containing both benzotriazoles represented by benzotriazole and tolyltriazole (methylbenzotriazole).

  However, zinc salts such as zinc chloride and zinc sulfate and benzotriazoles are extremely incompatible and difficult to prepare as a stable liquid composition. For this reason, zinc salts and benzotriazoles are separated from each other. However, there is a problem that a plurality of injection facilities are required and the injection management of the corrosion inhibitor becomes complicated.

  In order to solve the above problems, the present inventor has intensively studied a stable corrosion and scale preventing liquid composition containing zinc and benzotriazoles. As a result, by adding a certain amount of sulfuric acid to water, It has already been found that a stable liquid composition for preventing corrosion and scale containing benzotriazoles can be obtained, but in this composition, the proportion of active ingredients other than sulfuric acid and water is about 20% by weight. From the viewpoint of handleability and economy, a composition having a higher active ingredient blending ratio has been demanded.

  On the other hand, it has been known that a composition in which zinc nitrate and zinc oxide are dissolved in nitric acid has relatively good compatibility with benzotriazoles.

  Therefore, the present inventor has intensively studied the combination of sulfuric acid and nitric acid in order to obtain a liquid composition for containing corrosion and scale, containing zinc and benzotriazole, having a high active ingredient blending ratio, An acid mixture of sulfuric acid and nitric acid is added to adjust the pH to 0.0 to 2.5, and the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 to 1.0. A liquid composition for preventing corrosion and scale containing zinc and benzotriazole, and containing a mixture of sulfuric acid and nitric acid and an active ingredient other than water in a range of about 10 to 40% by weight. Found that can be obtained.

  That is, the invention according to claim 1 includes (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, zinc phosphate, (2) benzotriazoles, (3) organic phosphonic acid, phosphine. Add an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing one or more selected from finopolycarboxylic acid, phosphonocarboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer, and sulfonic acid group-containing polymer The pH is adjusted from 0.0 to 2.5, and the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 or more and less than 1.0. It is a liquid composition for corrosion and scale prevention.

  The invention according to claim 2 is (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, zinc phosphate, (2) benzotriazoles, (3) organic phosphonic acid, phosphinopoly PH is obtained by adding an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing at least one selected from carboxylic acid, phosphonocarboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer, and sulfonic acid group-containing polymer. The liquid composition for preventing corrosion and scale in which the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is from 0.7 to less than 1.0 It is a method for preventing corrosion and scale of iron-based metal and copper-based metal in an aqueous system characterized by adding an object.

  By adding the liquid composition for preventing corrosion and scale of the present invention, the effect of simultaneously preventing corrosion and scale of both iron-based metal and copper-based metal in a water circulation system in which iron-based metal and copper-based metal coexist Play. In addition, it contains both a corrosion inhibitor for ferrous metals and a corrosion inhibitor for copper-based metals, and also has a scale-preventing effect. Management is also easy. In addition, since it is possible to increase the proportion of the active ingredient in the composition, it is economical because it is possible to reduce manufacturing costs, distribution costs, and chemical injection equipment costs.

It is a systematic diagram which shows the test apparatus used for the Example.

Hereinafter, embodiments of the present invention will be described in detail.
The present invention is an invention relating to a corrosion and scale preventing liquid composition capable of simultaneously preventing corrosion of an iron-based metal and a copper-based metal in an aqueous system in which an iron-based metal and a copper-based metal coexist, and a method for preventing corrosion and scale, (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, zinc phosphate, (2) benzotriazoles, (3) organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, A pH of 0.0 to 2.5 is obtained by adding an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing at least one selected from phosphoric acid, a maleic acid polymer, an itaconic acid polymer, and a sulfonic acid group-containing polymer. And the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 or more and less than 1.0, Use liquid compositions as well as corrosion and scale prevention method using the same.

  The most preferred examples of the liquid composition for corrosion and scale prevention according to the present invention include (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, and zinc phosphate, (2) benzotriazoles, ( 3) Sulfuric acid in an aqueous mixture containing at least one selected from organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer, sulfonic acid group-containing polymer And an acid mixture of nitric acid is added to adjust the pH to 0.0 to 2.5, and the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 to less than 1.0 It is a liquid composition for preventing corrosion and scale.

The zinc used in the present invention is metallic zinc in the form of a plate, block, powder, rod, wire, etc., and commercially available products such as zinc and zinc powder can be used as they are. As the zinc hydroxide used in the present invention, commercially available zinc hydroxide can be used as it is. As zinc oxide, those commercially available as zinc oxide or zinc white can be used as they are. Zinc carbonate contains zinc bicarbonate, basic zinc carbonate, and zinc carbonate hydroxide, and is commercially available as zinc carbonate. Zinc phosphate contains zinc zinc phosphate Zn (H ₂ PO ₄ ) ₂ , dibasic zinc phosphate ZnHPO ₄ , and tertiary zinc phosphate Zn ₃ (PO ₄ ) ₂ and is commercially available as zinc phosphate. Things can be used as they are.

  These zinc compounds contain trace amounts of lead as impurities, but lead is not only harmful to the human body, but also precipitates insoluble lead sulfate in the composition, so the lead content in the zinc compound is 0. It is preferably 1% or less, and more preferably 0.03% or less.

  The blending amount of one or more zinc compounds selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, and zinc phosphate in the liquid composition for corrosion and scale prevention of the present invention is usually in the range of 1 to 10%. It is. If the blending amount of the zinc compound is less than 1%, the amount of the liquid composition necessary for anticorrosion is excessive, and if it exceeds 10%, a stable composition cannot be obtained, and therefore, neither is preferable.

（ここでＲはカルボキシル基、塩素、臭素、フッ素、ヨウ素、水酸基、ニトロ基、スルホン酸基、ホスホン酸基、アミノ基を示す）

（ここでＲ１は炭素数が１〜１２のアルキル基、Ｒ２は水素、炭素数が１〜１２のアルキル基、カルボキシル基、塩素、臭素、フッ素、ヨウ素、水酸基、ニトロ基、スルホン酸基、ホスホン酸基、アミノ基を示す） Examples of the benzotriazoles used in the present invention include 1,2,3-benzotriazoles represented by the following general formula (1) and alkyl-substituted-1,2,3-benzoates represented by the following general formula (2). And triazoles.

(Where R represents a carboxyl group, chlorine, bromine, fluorine, iodine, hydroxyl group, nitro group, sulfonic acid group, phosphonic acid group, amino group)

(Where R1 is an alkyl group having 1 to 12 carbon atoms, R2 is hydrogen, an alkyl group having 1 to 12 carbon atoms, carboxyl group, chlorine, bromine, fluorine, iodine, hydroxyl group, nitro group, sulfonic acid group, phosphonic group Acid group or amino group)

  These 1,2,3-benzotriazoles and alkyl-substituted-1,2,3-benzotriazoles may be used alone or in combination. Preferred 1,2,3-benzotriazoles include 1,2,3-benzotriazole, and preferred alkyl-substituted-1,2,3-benzotriazoles include 1,2,3-methylbenzotriazole. Is mentioned. Here, what is marketed as tolyltriazole can be used for 1,2,3-methylbenzotriazole.

  The blending amount of benzotriazoles in the corrosion and scale prevention liquid composition of the present invention is usually in the range of 0.2 to 10%. If the amount of benzotriazoles is less than 0.2%, the amount of liquid composition required for anticorrosion is excessive, and if it exceeds 10%, a stable composition cannot be obtained, and therefore, neither is preferred.

  The organic phosphonic acid used in the present invention is an organic compound having one or more phosphono groups in the molecule, specifically, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediamine. Examples include tetramethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, hexamethylene diamine tetramethylene phosphonic acid and the like, and 1-hydroxyethylidene-1,1-diphosphonic acid is preferable.

  The phosphinopolycarboxylic acid used in the present invention is a compound having one or more phosphino groups and two or more carboxyl groups in the molecule, and specifically reacts acrylic acid with hypophosphorous acid. Bis-poly (2-carboxyethyl) phosphinic acid obtained, bis-poly (1,2-dicarboxyethyl) phosphinic acid obtained by reacting maleic acid and hypophosphorous acid, maleic acid, acrylic acid and hypochlorous acid Poly (2-carboxyethyl) (1,2-dicarboxyethyl) phosphinic acid obtained by reacting phosphoric acid, bis-poly [2-carboxy- (2) obtained by reacting itaconic acid and hypophosphorous acid -Carboxymethyl) ethyl] phosphinic acid, a reaction product of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid and hypophosphorous acid, and the like. Reactants in acid and acrylic acid and hypophosphorous acid is the reaction product of itaconic acid and maleic acid and hypophosphorous acid.

  The preparation of phosphinopolycarboxylic acid is usually carried out by heating hypophosphorous acid and monoethylenically unsaturated carboxylic acid in an aqueous solvent in the presence of a free radical initiator, for example, JP-B-54-29316. No. 5, JP-B-5-57992 and JP-B-6-47113. Further, phosphinopolycarboxylic acids are commercially available from Bio Labs under trade names such as BELCLENE500, BELPERSE164, and BELCLENE400.

  The phosphonocarboxylic acid used in the present invention is an organic compound having one or more phosphono groups and one or more carboxyl groups in the molecule, specifically 2-phosphonobutane-1,2,4-tricarboxylic acid. Examples thereof include acid, hydroxyphosphonoacetic acid, phosphonopolymaleic acid, and phosphonic succinic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid and phosphonopolymaleic acid are preferable. Here, phosphonocarboxylic acid is commercially available from Rhodia under the trade name BRICORRR288 and from BWA under the trade name BELCOR585.

  The phosphonocarboxylic acid can be produced, for example, by heating phosphorous acid and monoethylenically unsaturated carboxylic acid in a neutral to alkaline aqueous solvent in the presence of a free radical initiator (for example, special (Kaihei 4-334392). The phosphonocarboxylic acid can be obtained by reacting a reaction product of hypophosphorous acid with a carbonyl compound or an imine compound with an unsaturated carboxylic acid in the presence of a reaction initiator (Japanese Patent No. 3284318). .

  As the phosphoric acid used in the present invention, commercially available phosphoric acid can be used as it is. Instead of phosphoric acid, within the range that does not affect the stability of the liquid composition for corrosion and scale prevention of the present invention, monosodium phosphate, disodium phosphate, monopotassium phosphate, dipotassium phosphate, etc. An alkali metal salt of phosphoric acid may be used.

  The maleic acid polymer used in the present invention is a homomaleic acid polymer and a copolymer of a monoethylenically unsaturated monomer copolymerizable with maleic acid.

  The itaconic acid polymer used in the present invention is a homoitaconic acid polymer and a copolymer of a monoethylenically unsaturated monomer copolymerizable with itaconic acid.

  Here, monoethylenically unsaturated monomers copolymerizable with maleic acid and itaconic acid include fumaric acid; (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyl alkyl ester; (meth) acrylamide, N -Alkyl substituted (meth) acrylamide; ethylene, propylene, isopropylene, butylene, isobutylene, hexene, 2-ethylhexene, pentene, isopentene, octene, isooctene, etc., which are olefins having 2 to 8 carbon atoms; vinyl methyl ether vinyl methyl Ether, vinyl ethyl ether; maleic acid alkyl ester, and the like, and one or more of them are used.

  The molecular weight of the maleic acid polymer and the itaconic acid polymer is preferably 300 to 20,000, more preferably 400 to 1,000 as the weight average molecular weight.

  A method for producing a maleic acid polymer can be produced by heating maleic anhydride or maleic acid in an organic solvent or an aqueous solvent in the presence of a free radical initiator, for example, Japanese Patent No. 2964154, This is disclosed in Japanese Patent Publication No. 7-49450 and Japanese Patent Laid-Open No. 6-298874.

  A method for producing an itaconic acid polymer can be produced by heating itaconic acid in an aqueous solvent in the presence of a free radical initiator, and is disclosed, for example, in JP-A-5-86129. .

  The sulfonic acid group-containing polymer used in the present invention is a polymer containing a monoethylenically unsaturated sulfonic acid. As the monoethylenically unsaturated sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy 2-hydroxy-1-propanesulfonic acid, conjugated diene sulfonated products such as butadiene sulfonic acid and isoprene sulfonic acid, styrene sulfonic acid, sulfoalkyl (meth) acrylate ester, sulfoalkyl (meth) allyl ether, sulfopheno (meth) allyl One or more of ether, (meth) allylsulfonic acid and the like are used.

  The sulfonic acid group-containing polymer used in the present invention is preferably a copolymer of monoethylenically unsaturated sulfonic acid and monoethylenically unsaturated carboxylic acid, or monoethylenically unsaturated sulfonic acid and monoethylenically unsaturated carboxylic acid. A copolymer of acid and other copolymerizable monoethylenically unsaturated monomers.

  Here, as the monoethylenically unsaturated carboxylic acid, one or more selected from acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride and the like are used. Other copolymerizable monoethylenically unsaturated monomers include (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyl alkyl ester; (meth) acrylamide, N-alkyl substituted (meth) acrylamide; carbon number 2-8 olefins such as ethylene, propylene, isopropylene, butylene, isobutylene, hexene, 2-ethylhexene, pentene, isopentene, octene, isooctene, etc .; vinyl alkyl ether vinyl methyl ether, vinyl ethyl ether; maleic acid alkyl ester 1 type or 2 types or more are used.

  The sulfonic acid group-containing polymer used in the present invention is more preferably a copolymer of 2-acrylamido-2-methylpropanesulfonic acid and (meth) acrylic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid And (meth) acrylic acid copolymer, conjugated diene sulfonated product and (meth) acrylic acid copolymer. The molecular weight of the sulfonic acid group-containing polymer is preferably 1,000 to 100,000 as the weight average molecular weight, more preferably 4,000 to 20,000.

  The organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer and sulfonic acid group-containing polymer used in the present invention are in the form of an unneutralized acid. However, it may be partially neutralized with an alkali metal hydroxide as long as it does not affect the stability of the liquid composition for preventing corrosion and scale of the present invention. Such a partially neutralized product is found when an alkali metal hydroxide is used as a polymerization catalyst such as a maleic acid polymer or an itaconic acid polymer.

  Commercially available sulfuric acid can be used as it is. There is no restriction on the concentration of sulfuric acid to be used, and any of concentrated sulfuric acid, dilute sulfuric acid and fuming sulfuric acid can be used, but it is preferable to use dilute sulfuric acid having a sulfuric acid concentration of less than 90% by weight from the viewpoint of safety during work.

  The nitric acid used in the present invention can be used as it is. There is no limitation on the concentration of nitric acid to be used, and either concentrated nitric acid or dilute nitric acid can be used, but it is preferable to use one having a nitric acid concentration of less than 70% by weight from the viewpoint of safety during work.

  In the acid mixture of the present invention, it is necessary that sulfuric acid and nitric acid are mixed, and the mixing ratio range is generally 10:90 to 90: 10% by weight as an active component of sulfuric acid: nitric acid. The ratio is preferably 25:75 to 75: 25% by weight.

  The pH of the liquid composition for preventing corrosion and scale according to the present invention is in the range of 0.0 to 2.5, and preferably the amount of sulfuric acid and / or nitric acid so that the pH is in the range of 0.2 to 2.0. Adjust. In this pH adjustment, it is desirable to use sulfuric acid from the viewpoint of reducing the load of nitrate nitrogen on the environment. If the pH is outside this range, a stable composition cannot be obtained. Moreover, when the compounding quantity of a sulfuric acid or nitric acid exceeds 10%, precipitation of a sulfate, an azole, etc. may become easy to produce depending on mixing | blending.

  The equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is preferably in the range of 0.7 to less than 1.2, more preferably in the range of 0.7 to less than 1.0. It is. If the equivalent ratio is outside this range, a stable composition cannot be obtained.

  The liquid composition for preventing corrosion and scale according to the present invention can be produced by adding each compound to water in an arbitrary order and stirring and mixing or dissolving. In that case, in order to accelerate | stimulate melt | dissolution of solid substances, such as benzotriazoles and a zinc compound, you may heat and cool as needed.

  A preferable production method is as follows. First, at least one selected from organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, phosphoric acid, maleic acid polymer, itaconic acid polymer, and sulfonic acid group-containing polymer is added to water. Then add the acid mixture of sulfuric acid and nitric acid, then add the benzotriazoles and stir until completely dissolved, then add the zinc compound and stir until completely dissolved, and finally if necessary with sulfuric acid This is a method of adjusting pH.

  The addition concentration of the liquid composition for corrosion and scale prevention of the present invention is not particularly limited, but is usually added so as to have a concentration of 5 to 10,000 mg / L with respect to the aqueous system, preferably 20 to 500 mg. / L.

  At the start of operation of the aqueous system, it is preferable to use a condensed phosphate together with the liquid composition for corrosion and scale prevention of the present invention. The condensed phosphate is a phosphate having a condensation degree of 2 or more, but pyrophosphate (condensation degree 2), tripolyphosphate (condensation degree 3), tetrapolyphosphate (condensation degree 4), hexametaphosphate, etc. Can be used. Generally, what is marketed under the trade name of sodium hexametaphosphate is a chain condensed phosphate having an average condensation degree of 10 or more, but a more preferable condensed phosphate has an average condensation degree of 30 to 100. It is a chain condensed phosphate.

  The addition amount of the condensed phosphate at the start of the aqueous operation is usually 3 to 200 mg / L, preferably 5 to 100 mg / L.

The quality of water to be treated to which the liquid composition for preventing corrosion and scale of the present invention is applied is not particularly limited, but usually pH 6.0 to 9.5, electric conductivity is 5000 μS / cm or less, Ca hardness or Mg hardness. 0 to 1000 mg CaCO ₃ / L, M alkalinity 0 to 500 mg CaCO ₃ / L, silica 0 to 250 mg / L, chloride ions 0 to 3000 mg / L, sulfate ions 0 to 3000 mg / L, total iron 10 ppm Or less, preferably 3 ppm or less, aluminum 3 mg / L or less, turbidity (or suspended matter concentration) is 100 degrees or less (100 ppm or less), preferably 20 degrees or less (20 ppm or less), and the stability index of the tuner is The saturation index of Langeria is 3.0 or more and 3.0 or less.

  Although the temperature of the to-be-processed water to which the liquid composition for corrosion and scale prevention of the present invention is applied is not particularly limited, it is usually in the range of 0 to 80 ° C. Moreover, the flow rate of the water system to be treated to which the liquid composition for preventing corrosion and scale according to the present invention is applied is not particularly limited, but is usually in the range of 0.1 to 5.0 m / s.

The half-life time of the treated water system to which the corrosion and scale preventing liquid composition of the present invention is applied is not particularly limited, but is usually 300 hours or less. Where the half time is the formula:
Half-time [h] = (Retained water amount [m ³ ] / blow-down water amount [m ³ /h])×0.693

  Another type of compound known as a corrosion inhibitor, a scale inhibitor, a microbial disorder inhibitor, or a known compound as an antifoaming agent may be used in combination with the composition of the present invention. Although microbial damage as well as corrosion and scale are major obstacles in water systems, it is particularly preferable to use a microbial damage inhibitor in combination because the liquid composition for preventing corrosion and scale according to the present invention cannot prevent microbial damage.

  Examples of the microbial disorder inhibitor used in combination with the composition of the present invention include sodium hypochlorite, calcium hypochlorite, liquefied chlorine, bromine chloride, a reaction product of hypochlorite and bromide, chloroisocyanuric acids, Compounds that dissolve in water such as chlorodimethylhydantoic acid, bromodimethylhydantoic acid, chlorobromodimethylhydantoic acid, etc. to produce hypochlorous acid and / or hypobromite; hydrazine; 2-methylisothiazolin-3-one, 2- Methyl-4-chloroisothiazolin-3-one, 2-methyl-5-chloroisothiazolin-3-one, 2-methyl-4,5-dichloroisothiazolin-3-one, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-3 (2H Isothiazoline compounds such as isothiazoline; organic bromide compounds such as 2,2-dibromo-2-nitroethanol, 2-bromo-2-nitropropane-1,3-diol, 2,2-dibromo-3-nitrilopropionamide; methylene Bisthiocyanate, bis- (1,4-dibromoacetoxy) -2-butene, benzyl bromacetate, sodium bromide, α-bromocinnamaldehyde, 2-pyridinethiol-1-oxide sodium, bis (2-pyridinethiol- 1-oxide) zinc, 2- (4-thiazolyl) benzimidazole, hexahydro-1,3,5-tris- (2-hydroxyethyl) -S-triazine, bis (trichloromethyl) sulfone, dithiocarbamate, 3,5 -Dimethyltetrahydro-1,3,5,2H Thiadiazine-2-thione, bromoacetic acid ethylthiophenyl ester, α-chlorobenzoaldoxime acetate, 2,4,5,6-tetrachloroisophthalonitrile, 1,2-dibromo-2,4-dicyanobutane, 3- Examples thereof include iodo-2-propenyl butyl carbamate, salicylic acid, sodium salicylate, paraoxybenzoic acid ester and p-chloro-m-xylenol.

The microbial disorder inhibitor that is preferably used in combination with the liquid composition for preventing corrosion and scale according to the present invention is a compound that generates hypochlorous acid and / or hypobromite, but the amount added is free halogen concentration (free The sum of chlorine and free bromine) is usually 0.05 to ₂ mg / L (in terms of Cl ₂ ).

  In the corrosion and scale prevention liquid composition and the corrosion and scale prevention method of the present invention, the form of corrosion to be targeted is not particularly limited, but general corrosion, pitting corrosion, crevice corrosion, oxygen concentration cell corrosion, stress corrosion cracking, Examples include galvanic corrosion, microbial corrosion, flow-induced local corrosion, erosion corrosion, cavitation corrosion, decomponent corrosion, and dezincification corrosion.

  In the corrosion and scale prevention liquid composition and the corrosion and scale prevention method of the present invention, the types of scales are not particularly limited, but carbonate scales such as calcium carbonate and magnesium carbonate; calcium sulfate, barium sulfate and sulfuric acid. Sulfate scales such as strontium; phosphate scales such as calcium phosphate, zinc phosphate, iron phosphate, and aluminum phosphate; silicic acids such as magnesium silicate, calcium silicate, aluminum silicate, iron silicate, and zinc silicate Salt scale; amorphous silica scale; magnesium hydroxide; aluminum hydroxide; iron oxide and iron hydroxide.

  Metals forming a passivating film such as stainless steel and titanium are prone to pitting corrosion and stress corrosion cracking due to crevice corrosion at the scale adhering portion, but the liquid composition for preventing corrosion and scale of the present invention and In the method for preventing corrosion and scale, the corrosion of the metal forming the passivated film such as stainless steel and titanium can be indirectly prevented by preventing the scale from adhering.

  The present invention will be specifically described below, but the present invention is not limited to these examples. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

[Preparation of liquid composition for corrosion and scale prevention]
(Compounds used to prepare the composition)
1. HEDP: 1-hydroxyethylidene-1,1-diphosphonic acid (organic phosphonic acid)
1. Active content 60%, Na content 0.1% or less Phosphinopolycarboxylic acid (1): acrylic acid and 2-acrylamido-2-methyl
Propanesulfonic acid and hypophosphorous acid (molar ratio 16: 2: 1)
Copolymer, BELCLENE400 manufactured by BWA
(Trade name), active content 50%, Na content 0.7%
3. Phosphinopolycarboxylic acid (2): acrylic acid-maleic acid-hypophosphorous acid
(2: 1: 1) copolymer, active content 34.8%,
Na content 21.3%
4). Phosphonocarboxylic acid (1): 2-phosphonobutane-1,2,4-tricarboxylic acid,
4. Active content 50%, Na content 0.1% or less Phosphonocarboxylic acid (2): phosphonopolymaleic acid (average degree of polymerization 1.5),
Rhodia BRICORRR288 (trade name),
Active content 30%, Na content 10.0%
6). 6. Phosphoric acid: active content 75%, Na content not detected Polymaleic acid: homomaleic acid polymer (average molecular weight 500), manufactured by BWA
BELCLENE200LA (trade name),
7. Active content 50%, Na content 0.1% or less Polyitaconic acid: homoitaconic acid polymer (average molecular weight 1,000),
8. Active content 23%, Na content 2.3% or less Sulfonic acid group-containing polymer (1): acrylic acid and 2-acrylamido-2-methyl
Propanesulfonic acid copolymer [copolymerization ratio (weight) 60:
40, weight average molecular weight 10,000], active content 40%,
Na content 0.1% or less10. Sulfonic acid group-containing polymer (2): acrylic acid and 3-allyloxy-2-hydroxy
Copolymer of cis-1-propanesulfonic acid, [copolymerization ratio (heavy
Amount) 50:50, weight average molecular weight 5,000],
10. Active content 40%, Na content 0.1% or less Sulfonic acid group-containing polymer (3): Copolymerization of acrylic acid and isopropyl sulfonic acid
Copolymer [copolymerization ratio (weight) 50:50, weight average molecular weight
10,000], active content 40%, Na content 0.1% or less
Bottom 12. Zinc powder: purity 99.2%, lead 0.02%, average particle size 4μm
13. Zinc oxide: pure content 99.5% or more, zinc content 80.3%, lead 0.03% or less,
Cadmium 0.01% or less
(JIS K1410: Two kinds of zinc oxide acceptable products)
14 Basic zinc carbonate: zinc content 57.0-60.0%, lead 10ppm or less Tertiary zinc phosphate tetrahydrate: zinc content 42.7%, phosphoric acid content 41.4%
(PO ₄ equivalent), lead 0.01% or less Zinc sulfate heptahydrate: 99.5% or more pure, zinc content 22.6%
17. Zinc sulfate monohydrate: pure content 98% or more, zinc content 35.7%
18. Zinc chloride: 99% or more pure content, zinc content 48.0%
19. Zinc hydroxide: Zinc content 65.8%
20. Polyacrylic acid: homoacrylic acid polymer (average molecular weight 2,200),
Active content 40%, Na content 0.1% or less

(Preparation of a composition containing 10 to 30% by weight of an active ingredient other than an acid mixture and water)
Each raw material was added to water and dissolved in accordance with the order of description of the composition of the compositions shown in Table 1 and Table 2. Next, after measuring the pH and zinc content of the composition, 100 mL of each composition was placed in a 125 mL glass bottle, covered, and allowed to stand in an incubator at each temperature of −5 ° C., 25 ° C., and 50 ° C. The separation stability after months was examined. The results are shown in Tables 1 and 2.

  The separation stability of the liquid composition which is an example of the present invention shown in Table 1 is not separated by precipitation compared to the comparative example shown in Table 2, and the blending ratio of active ingredients other than the acid mixture and water is low. 10 to 30% by weight of the liquid composition of the present invention solves the problem that the zinc salt and benzotriazoles are extremely incompatible and difficult to prepare as a stable liquid composition. It was shown that triazoles can be blended stably.

(Preparation of a composition having a mixture ratio of active ingredients other than acid mixture and water of 40% by weight or more)
Each raw material was added to water and dissolved in the order of description of the composition of the compositions shown in Table 3 and Table 4. Next, after measuring the pH and zinc content of the composition, 100 mL of each composition was placed in a 125 mL glass bottle, covered, and allowed to stand in an incubator at each temperature of −5 ° C., 25 ° C., and 50 ° C. The separation stability after months was examined. The results are shown in Tables 3 and 4.

  By adding a certain amount of sulfuric acid to water, the present inventor has a stable liquid composition for preventing corrosion and scale containing zinc and benzotriazole, containing about 20% by weight of an active ingredient other than sulfuric acid and water. As described above, the liquid composition of the present invention can be obtained from the results of the examples of the present invention shown in Table 3 and the comparative examples shown in Table 4. It was shown that a stable liquid composition having an active ingredient blending ratio of 40% by weight or more other than the acid mixture and water can be obtained.

[Evaluation of corrosion prevention effect and scale prevention effect of liquid composition]
No. 1 prepared in the preparation test of the liquid composition for preventing corrosion and scale. 24-No. 27, and no. 28-No. 31 was evaluated for corrosion prevention effect and scale prevention effect.

(Test equipment)
The test apparatus and test method used for evaluating the method of the present invention conformed to the on-site test method of JIS G0593-2002 “Test Method for Evaluation of Corrosion and Scale Prevention of Water Treatment Agent”. An outline of the test apparatus is shown in FIG. A carbon steel tube STKM11A (JIS G3445) having an outer diameter of 12.7 mm and a length of 510 mm was used as a test heat transfer tube, and aluminum brass C6871 (JIS H3300) was used as a copper alloy. The water capacity of the entire system including the water tank 2 and the piping was 62 L, and the water temperature was controlled by the water temperature controller 9 so that the water temperature of the water tank was 35 ° C. Water is passed through the circulation pump 3 while being controlled by the flow rate adjusting valve 5 so that the flow rate is 210 L / h corresponding to the linear flow rate of 0.3 m / s in the test heat transfer tube evaluation unit, and the heat flux of the heat exchanger 7 is 70 kW. / M ² . The cooling tower 1 used was an induced draft counterflow contact type having a cooling capacity of 1.8 cooling tons. The temperature difference between the circulating water at the inlet and outlet of the cooling tower was 15 ° C. The amount of evaporated water was 4.4 L / h, the amount of makeup water was 5.5 L / h, the amount of blowdown water was 1.1 L / h, and the concentration was 5 times. The electric conductivity of the circulating water is continuously measured by the electric conductivity measuring cell 4 so that the electric conductivity corresponding to five times the concentration is obtained by using the electric conductivity controller 11 from the electric conductivity input signal. The blowdown pump 10 was controlled.

(Test method)
Yokkaichi city water was used as makeup water 12. The water quality of Yokkaichi city water is pH: 7, electrical conductivity: 13 mS / m, Ca hardness: 38 mg-CaCO ₃ / L, Mg hardness: 8 mg-CaCO ₃ / L, M alkalinity: 40 mg-CaCO ₃ / L, chloride Product ion: 10 mg / L, sulfate ion: 11 mg / L, silica: 12 mg / L.
As an initial treatment, Yokkaichi City water was spread in the water tank, 200 mg / L of the composition to be tested and 12.5 mg / L of sodium hexametaphosphate (average condensation degree 40) were added, and the mixture was circulated at room temperature for 48 hours. Thereafter, the heat load was started, and the concentration reached 5 times 3 days after the start of the heat load. Therefore, blowdown was immediately started to maintain the concentration at 5 times. Simultaneously with the start of blowdown, 25 mg / L of the composition to be tested was added to the blowdown amount by the water treatment agent injector 13. The test period was one month. After the test was completed, the test heat transfer tube was removed, and the corrosion rate, maximum corrosion depth, and adhesion rate were measured. The results are shown in Table 5.

  Liquid composition No. which is an example of the present invention. 24-No. The anti-corrosion effect and the anti-scale effect of No. 27 are the liquid composition No. 28-No. Both the carbon steel and the copper alloy are superior to the effect of 31, and the liquid composition of the present invention corrodes both the iron-based metal and the copper-based metal in a water circulation system in which the iron-based metal and the copper-based metal coexist. It has been shown to be a liquid composition for corrosion and scale prevention that can effectively prevent scale simultaneously.

  The present invention provides corrosion prevention for both iron-based metals and copper-based metals in water systems such as open circulation cooling water systems, closed circulation cooling water treatment agents, transient cooling water systems, circulating cold / hot water systems, and circulating heating water systems. It can be used for scale prevention.

DESCRIPTION OF SYMBOLS 1 Cooling tower 2 Water tank 3 Circulation pump 4 Electrical conductivity measurement cell 5 Flow rate adjustment valve 6 Flowmeter 7 Heat exchanger 8 Test piece holder 9 Water temperature control device 10 Blow down pump 11 Electrical conductivity control device 12 Supply water 13 Water treatment Agent injection device

Claims (2)

  (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, zinc phosphate, (2) benzotriazoles, (3) organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, A pH of 0.0 to 2.5 is obtained by adding an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing at least one selected from phosphoric acid, a maleic acid polymer, an itaconic acid polymer, and a sulfonic acid group-containing polymer. And an equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 or more and less than 1.0, and a liquid composition for preventing corrosion and scale. (1) one or more selected from zinc, zinc hydroxide, zinc oxide, zinc carbonate, zinc phosphate, (2) benzotriazoles, (3) organic phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, A pH of 0.0 to 2.5 is obtained by adding an acid mixture of sulfuric acid and nitric acid to an aqueous mixture containing at least one selected from phosphoric acid, a maleic acid polymer, an itaconic acid polymer, and a sulfonic acid group-containing polymer. And a liquid composition for preventing corrosion and scale, wherein the equivalent ratio of the total amount of sulfuric acid and nitric acid to the total amount of zinc and alkali metal is 0.7 to less than 1.0, is added. To prevent corrosion and scale of ferrous metals and copper-based metals in water systems.

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