JPS6295200A - Corrosion and scale preventive agent for metals in aqueous system - Google Patents

Abstract

PURPOSE:To eliminate the hazard by polymerized phosphoric acids and to simultaneously prevent the corrosion and scale of metals in an aq. system by using phosphonic acids in place of the polymerized phosphoric acids. CONSTITUTION:1) A phosphonic acid and/or the water soluble salt thereof, 2) thiazoles and/or the water soluble salt thereof and 3) a binary or quaternary copolymer consisting of the monomer selected from the group consisting of the monomers A expressed by the formula I (X1, X2 are H, methyl group, M is H, alkali metal, alkaline earth metal, zinc, ammonium group or org. amine group) and the monomer selected from the group consisting of another monomers B expressed by the formula II (Y1, Y2 are H, methyl group, Z is the formulas III-V, M is H, alkali metal, alkaline earth metal, zinc, ammonium group, org. amine group, R1, R2 are H, methyl group, n is 1-3 integer) as the essential monomers are incorporated as effective components into a titled agent. As a result, the corrosion and scale of the metals in the aq. soln. are simultaneously prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field The present invention provides synergistic water treatment that simultaneously prevents corrosion and scale deposition of metal materials such as heat exchangers and piping in aqueous systems including cooling water systems. B. Prior Art Conventionally, methods of adding polymerized phosphoric acids have been widely used for the purpose of preventing corrosion of metals that come into contact with effluent in cooling water systems and the like. However, on the other hand, the addition of polymerized phosphoric acids as a corrosion preventive agent has been viewed as problematic in that it causes various secondary problems. For example, polymerized phosphoric acids easily hydrolyze in water to orthophosphoric acid, which has a poor anticorrosion effect, due to the action of heat-supported microorganisms.

Orthophosphoric acid reacts with ions such as carnoum, zinc, and iron in water to form scales and deposits such as dissolvable carnoum phosphate, lead phosphate, and iron phosphate, which facilitates heat exchange. Obstruction of heat transfer in vessels 1. Causes problems such as blockage of water channels and crevice corrosion on metal surfaces.

Particularly throughout the year, there is a trend to minimize drainage from cooling water systems in order to conserve water resources, eutrophication of lakes and marshes due to phosphorus-containing drainage, and red tide occurrence in inner bays.As a result, the cooling of polymerized phosphoric acid The residence time in the aqueous system is increased and the possibility of undergoing +10 water splitting is increased.

At the same time, in the open shield ring cooling water system, some of the cooling water evaporates, so reducing the amount of water discharged from the system increases the concentration rate of dissolved salts in the make-up water. Orthophosphoric acid generated by hydrolysis of polymerized phosphoric acids promotes the formation of scales and deposits.

In view of the drawbacks of these polymerized phosphoric acids, phosphonic acids have recently been used in some cases in place of polymerized phosphoric acids. Compared to polymerized phosphoric acids, phosphonic acids are generally less susceptible to hydrolysis by heat and microorganisms, but on the other hand, phosphonic acids have the disadvantage that sufficient anticorrosive effects cannot be expected even when used alone. For this reason, some methods have been implemented in which phosphonic acids are used in combination with zinc compounds, azole compounds, etc. to supplement the anticorrosion effect.

However, when using zinc compounds, when the pH of hydrogen becomes 8 or higher, the solubility of zinc decreases, and the soluble zinc necessary to maintain the corrosion protection effect precipitates as zinc hydroxide, resulting in insufficient corrosion protection. It no longer shows any effect. Regarding azole compounds, even if they are used in combination with phosponic acids, a sufficient anticorrosive effect on carbon steel cannot be expected. Furthermore, when added in excess, phosphonic acids react with calcium and zinc in water to form scale deposits of calcium bosponate and zinc phosphonate. In addition, phosphonic acids are Nord,
U in water such as iron oxide and iron hydroxide! , cannot prevent the harmful accumulation of turbidity.

C2 Problems to be Solved by the Invention The purpose of the present invention is to solve the drawbacks and problems mentioned above. The present inventors focused on the advantage that phosphonic acids are difficult to hydrolyze compared to polymerized phosphoric acids, and aimed to improve the anticorrosion effect of phosphonic acids and suppress the accumulation of scale stains when phosphonic acids are used. Intensive research into methods and synergistic compositions has led to the completion of the present invention. The purpose of the present invention is to eliminate the secondary damage caused by polymerized phosphoric acids by using phosphonic acids instead of polymerized phosphoric acids, and to have an excellent anticorrosion effect. A synergistic water treatment composition that can prevent scale deposition caused by reaction with zinc and the extrusion and deposition of other poorly soluble salts in water, and can simultaneously prevent corrosion of metals and scale deposition in water systems. , and by adding acid to prevent phosphoric acid scale, such as in conventional cooling water treatment using polymerized phosphoric acids1)
I-(The objective is to provide a composition that does not require any control.

Means for Solving Problem D7 The corrosion and scale inhibitor of the present invention comprises: 1. (1) phosphonic acid and/or a water-soluble salt thereof;
(2) Azoles and/or water-soluble salts thereof, and (3
) Monomer (A) represented by the following formula (where, represents an organic amine group) and another monomer (B) represented by the following formula (where Yl and Y2 are each independently hydrogen or methyM is Hydrogen atoms, alkali metals, alkaline earth metals.

Zinc, ammonium group or organic amine group, R1゜R2
represents hydrogen or a methyl group, and n represents an integer of 1 to 3. ) and a binary or quaternary copolymer consisting of at least one monomer selected from the group consisting of:

Examples of the phosphonic acids used in the present invention include 2-phosphonobutane-1,2,4-dicarboxylic acid, 1-phosphonopropane-2,3-dicarboxylic acid, phosphonosuccinic acid,
Phosphonocarboxylic acids such as α-methylphosphono, conozylic acid, 1-phosphonopropane-1,2,3-1-dicarboxylic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid acids, aminophosphonic acids such as diethylenetriaminepentamethylenephosphonic acid,
1-Hydroquinethylidene-1,1-disulfonic acid, ■-
Examples include hydroxy-substituted lower alkylenephosphonic acids such as hydroquine propylidene-1,1-disulfonic acid. The most preferred phosphonic acids are 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroquineethylene-11. - disulfonic acid and aminotrimethylenephosphonic acid. The phosphonic acids used in the present invention refer to phosphonic acids and water-soluble salts thereof. The water-soluble salt mentioned here means that some or all of the protons of the phosphoric acid group and/or carboxyl group are alkali metal,
It is substituted with alkaline earth metals, zinc, ammonia and/or amines, and is therefore soluble at the concentration used.

Azoles used in the present invention include 1.2.3-
Triazole, 1.2.3-benzotriazole, tolyltriazole (i.e. 4-methyl-1,H-hencytriazole and 5-methyl-1,1-1-hencytriazole), 4-carboxine-IH-benzotriazole, 4 -triazoles such as nitro-1,8-benzotriazole, 2-mercaptobenzothiazole, 5
-Chloro-2-mercaptobenzothiazole, 2-(3
'-aminopropyl)-benzothiazole, 2-(
Thiazoles such as 2'-amino-2'-methylpropyl)-benzothiazole, 2-(5'-aminopentyl)benzimidazole, 2-(2'-amino-2
Examples include imidazoles such as '-methylpropyl)-bezimidazole, 2-ethyl-4-methyl-imidazole, 2-ethylimidazole, and 2-methylimidazole. The most preferred azoles are 1,2,3-benzotriazole, tolyltriazole, 2-mercaptobenzothiazole and 2-(5'-aminopentyl)benzimidazole. The azoles used in the present invention can also be added as water-soluble salts of alkali metals, ammonia, amines, and the like.

In the copolymer used in the present invention, the general formula (A
Examples of the monomer represented by ) include acrylic acid, methacrylic acid, crotonic acid, or water-soluble salts thereof. The term "water-soluble salt" as used herein refers to a salt in which part or all of the protons of the carboxyl group are substituted with an alkali metal, alkaline earth metal, zinc, ammonia, and/or amines, and is soluble at the concentration used. Further, as the monomer represented by the general formula (B), styrenesulfonic acid, toluenesulfonic acid, 2-acrylamide-
Examples include 2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, sulfopropylacrylic acid, sulfopropylmethacrylic acid, and water-soluble salts thereof. The term "water-soluble salt" as used herein refers to a salt in which some or all of the protons of the sulfonic acid group are substituted with an alkali metal, alkaline earth metal, zinc, ammonia, and/or amines, so that it can be dissolved at the concentration used.

The copolymer may be a terpolymer or a quaternary copolymer containing two or more of either one or both of the copolymer monomer (A) and monomer (B). Further, it may be a terpolymer or a quaternary copolymer containing monomer (A) and a third monomer other than monomer (B). Examples of the third monomer include acrylamide, maleic acid, maleic anhydride, fumaric acid, hinyl acetic acid, styrene, itaconic acid, acrylic acid alkyl esters, methacrylic acid alkyl esters, vinyl sulfonic acid, allyl sulfonic acid, etc. There is.

The preferred polymerization ratio in the copolymer is that the total amount of monomers (A) is 10 to 90%, and the total amount of monomers (B) is 10 to 90%.
% by weight, the total of components other than monomer (A) and monomer (B) is 10% by weight or less, and a more preferable polymerization ratio is a total of 30 to 70% by weight of monomer (A), monomer The total amount of body (B) is 30 to 70% by weight.

The preferred molecular weight of the copolymer is 1 as a weight average molecular weight.
000 to 100,000, more preferably 2.0
00-30.000. Here, the weight average molecular weight is measured by gel permeation chromatography (GPC) using polyethylene glycol whose molecules are all known as a standard substance. Examples of preferred copolymers include copolymers of acrylic acid and styrene sulfonic acid, copolymers of methacrylic acid and styrene sulfonic acid, copolymers of acrylic acid and toluenesulfonic acid, and copolymers of methacrylic acid and toluenesulfonic acid. , acrylic acid and 2-acrylamide-2
-Copolymers of methylpropanesulfonic acid, copolymers of methacrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, and the like.

In the present invention, each component of the inhibitor may be added to the system alone, or may be added as a preparation with other compounds as necessary. These compounds and formulations are injected continuously or intermittently to maintain sufficient concentrations within the system to achieve corrosion, scale and fouling control. The amount of phosponic acids added is 0.2 to 30 ppm, more preferably 1 to 1 Op.
pm, the amount of azole added is 0.2 to 20 ppm
, more preferably 0.5 to 5 ppm% The amount of copolymer added is 05 to 1100 ppm, more preferably 2 to 30 ppm.
It is.

As a guideline for water scale and corrosivity, Ryzn
A stability index of er is commonly used.

Ryzner's stability index = 2pHs - pH where: pHs: pH of water when CaCO3 is saturated
H: p■ of actual water] When the Ryzner stability index is less than 6, water becomes scaly, and when it is 6 or more, it becomes highly corrosive.

When the Ryzner stability index is 6 or more, the corrosiveness of water increases, so it is necessary to increase the usage rate of the treatment agent in the present invention. At this time, by further adding a zinc compound to the treatment agent of the present invention, corrosion can be suppressed at an economical treatment agent concentration.

The copolymer that is a component of the present invention has an excellent effect of dissolving and dispersing zinc compounds, and has an excellent ability to dissolve and disperse zinc compounds.
Even when the ratio is 8 or more, zinc does not precipitate and the anticorrosion effect can be maintained. The zinc compound used in the present invention may be any compound as long as it dissolves at the concentration used and releases zinc ions, but zinc chloride, zinc sulfate, and zinc nitrate are preferred.

These include zinc acetate, zinc carbonate, and zinc citrate.

The amount of zinc compound added is 0.2 to 30 ppm as zinc,
More preferably, it is 1 to loppm. Each zinc compound may be added to the system alone, or may be added in a formulation together with other zinc compounds. It is possible to further add chemicals known as corrosion inhibitors and scale inhibitors to the treatment agent of the present invention. Examples of such chemicals are chromates, @chromates, anhydrous romates, orthophosphoric acid and its water-soluble salts, 9-polymerized phosphoric acid and its water-soluble salts, molybdates, dinitrites, and silicates.

a) Phosphic acid esters and their water-soluble salts, phosphinic acids and their water-soluble salts, lignyline sulfonates.

Contains tannins.

E. Actual example Next, the present invention will be explained in more detail using actual examples.

Example 1 A test cooling tower with a total length of 50 cm and a water capacity of 30 children
Four double tongue width test heat exchangers were connected in series, and water was circulated at a water flow rate of 0.5 m/s using a centrifugal pump.

The material of the test heat exchanger tube was carbon steel (JIS 5TPG, outer diameter 12.7 mm), and an electric heater was inserted inside the heat exchanger tube to generate 30.0 QOKcal/m2. A heat flow rate of h was given to heat the circulating water and the outlet temperature of the cooling water was adjusted to 45°C. 2 for evaporated water in a cooling tower. (le/
Blowdown is performed using a metering pump so that the concentration of the circulating water is constant, and the corrosion and scale inhibitor of the present invention is supplied using a chemical feeder.
The concentration of chemicals in the circulating water was maintained at a constant level. The test period is 15 days. After the test was completed, the test heat exchanger tube was dried and weighed (7), then the accessories were removed and weighed. L
, ... test machine weight [mg21.3.
// Weight after removing deposits Cmgl S,: Surface area of 1dm21S2.
〃 Surface area [cm”)D Test period
[Day] For the first day of the test, initial high concentration treatment was carried out at twice the test concentration shown in Table -■.

The quality of the circulating water is pI-(9,2, electrical conductivity 1700μ
S/am.

M alkalinity 330ppm, total hardness 540ppm, C
The hardness was 360 ppm, the phosphor content was 96 ppm, and the chlorine ion was 210 ppm.

The concentration of the circulating water was 6, and the make-up water contained 1 ppm of iron. Ryzner's stability index at 40°C is 40.

The results are shown in Table 1.

Example 2 The dissolution and dispersion performance of the corrosion support and scale inhibitor of the present invention in zinc was evaluated.

Calcium chloride, magnesium chloride in deionized water.

Test water with the following water quality was prepared by dissolving sodium bicarbonate and zinc sulfate: Ca concentration 300 ppm.

Mg hardness 150ppm, HC03300ppm (Ca
as Co3).

Z nlOppm. The compounds shown in Table 2 were added to the test water, and the p II-I of the test water was adjusted to 85. The test solution was placed in an airtight container and allowed to stand in a constant temperature bath at 50°C for 3 days, then the test water was filtered through a 0.45μ thick membrane filter and the zinc concentration was measured by atomic absorption spectrometry.

The results are shown in Table-2.

Example 3 Using the same test equipment as in Example I, initial high concentration treatment was performed at twice the test concentration shown in Table 3 for the first day of the test.

The quality of the circulating water is pH 8.2, electrical conductivity 825 μS.
/cm.

M alkalinity 65ppm, total hardness 225pT) m, C
aHardness 176 ppm.

The silica content was 50 ppm and the chlorine ion content was 72 ppm. The concentration of the circulating water is 4, and the Ryzner stability index at 40°C is 6.9. The results are shown in Table-3.

(The following is a blank space) Table-2 Each copolymer A, B, C, D' and F is the same as that described in Table-1.

F1 Effects of the Invention According to the corrosion and scale inhibitor of the present invention, corrosion and scale accumulation of metal materials, particularly carbon steel heat exchangers and piping, etc. in water systems including cooling water systems are significantly suppressed at the same time. First, secondary damage caused by polymerized phosphoric acids,
All problems of secondary scale deposition caused by phosphonic acids are eliminated, and this has a great effect on the maintenance and management of water treatment facilities.

Patent applicant: Hakuto Chemical Co., Ltd. February 2C, 1986

Claims (1)

[Claims] 1. (1) phosphonic acid and/or a water-soluble salt thereof;
(2) Azoles and/or water-soluble salts thereof, and (3
) Monomer (A) represented by the following formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (A) (Here, X_1 and X_2 each independently represent hydrogen or a methyl group, and M represents a hydrogen atom, an alkali metal, or an alkali At least one monomer selected from the group consisting of earth metals, zinc, ammonium groups, or organic amine groups; and another monomer (B) represented by the following formula: ▲ Numerical formula, chemical formula, table, etc. ▼ (Here, Y_1 and Y_2 each independently represent hydrogen or methyl group, or Z is ▲a mathematical formula, chemical formula, table, etc.▼,
▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, M is a hydrogen atom, alkali metal, alkaline earth metal, zinc, ammonium group or organic amine group, R_1, R_2
represents hydrogen or a methyl group, and n represents an integer of 1 to 3. ) and at least one monomer selected from the group consisting of: and a binary or quaternary copolymer as an essential monomer. An inhibitor that simultaneously prevents corrosion and scaling. 2. The phosphonic acid and/or its water-soluble salt consists of 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid and their water-soluble salts. An inhibitor according to claim 1 selected from the group. 3. The azole according to claim 1, wherein the azole is selected from the group consisting of 1,2,3-benzotriazole, tolyltriazole, 2-mercaptobenzothiazole and 2-(5-aminopentyl)benzimidazole. Inhibitor. 4. The copolymer is a copolymer of acrylic acid and/or methacrylic acid and styrene sulfonic acid, acrylic acid and/or
or a copolymer of methacrylic acid and toluenesulfonic acid,
The inhibitor according to claim 1, which is selected from the group consisting of copolymers of acrylic acid and/or methacrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. 5. The molecular weight of the copolymer is 1,00 as a weight average molecular weight.
The inhibitor according to claim 1 in the range of 0 to 100,000. 6. Claim 1, in which the copolymer comprises 10 to 90% by weight of the total amount of monomer (A) and 10 to 90% by weight of the total amount of monomer (B) Inhibitors listed. 7. (1) Phosphonic acid and/or its water-soluble salt, (2) Azoles and/or its water-soluble salt, (3)
) Monomer (A) represented by the following formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (A) (Here, X_1 and X_2 each independently represent hydrogen or a methyl group, and M represents a hydrogen atom, an alkali metal, or an alkali At least one monomer selected from the group consisting of earth metals, zinc, ammonium groups, or organic amine groups; and another monomer (B) represented by the following formula: ▲ Numerical formula, chemical formula, table, etc. ▼(B) (Here, Y_1 and Y_2 each independently represent a hydrogen or methyl group, and Z is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, etc. , tables, etc.▼, or ▲mathematical formulas, chemical formulas, tables, etc.▼, M is a hydrogen atom, alkali metal, alkaline earth metal, zinc, ammonium group, or organic amine group, R_1, R_2
represents hydrogen or a methyl group, and n represents an integer of 1 to 3. ); a binary or quaternary copolymer as an essential monomer; and (4) a water-soluble salt zinc compound as an active ingredient. An inhibitor that simultaneously prevents corrosion and scaling of metals in a water system. 8. Phosphonic acid and/or its water-soluble salt consists of 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-disulfonic acid, aminotrimethylenephosphonic acid and their water-soluble salts An inhibitor according to claim 7 selected from the group. 9. Prevention according to claim 7, wherein the azole order is selected from the group consisting of 1,2,3 benzotriazole, tolyltriazole, 2-mercaptobenzothiazole and 2-(5-aminopentyl)benzimidazole. agent. 10. The copolymer is selected from the group consisting of a copolymer of acrylic acid and/or methacrylic acid and toluenesulfonic acid, and a copolymer of acrylic acid and/or methacrylic acid and 2-acrylamido-2-methylpropanesulfonic acid. The inhibitor according to claim 7. 11. The molecular weight of the copolymer is 1.0 as a weight average molecular weight.
Claim 7 in the range of 00 to 100,000
Inhibitors listed in section. 12. The copolymer contains 10 to 90% of the total amount of monomer (A)
% by weight and 10 to 90% by weight of the total amount of monomer (B). 13. Claim 7, wherein the water-soluble zinc compound is at least one zinc compound selected from the group consisting of zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, zinc carbonate, and zinc citrate. Inhibitor.