JP6566010B2 - Metal anticorrosive for cooling water and processing method of cooling water system - Google Patents

Description

  The present invention relates to a metal corrosion inhibitor for cooling water that suppresses corrosion of metals such as pipes and heat exchangers through which cooling water flows, and a method for treating a cooling water system using the metal corrosion inhibitor for cooling water.

Metal members provided in an open circulating cooling water system, such as carbon steel, copper, or copper alloy heat exchangers, reaction kettles, and pipes are generally corroded by contact with cooling water. Corrosion protection treatment is applied.
Phosphorus compounds such as orthophosphate, hexametaphosphate, hydroxyethylidenephosphonate, and phosphonobutanetricarboxylate are added to the cooling water in order to suppress corrosion of carbon steel heat exchangers and reaction kettles and piping. ing. A heavy metal salt such as zinc salt or dichromate may be added alone or in combination.
In particular, in the case of low hardness water quality, the anticorrosion effect due to the hardness component cannot be expected, so corrosion is likely to occur compared to the water quality with high hardness, and in order to obtain a sufficient anticorrosion effect, a certain amount or more of phosphate, etc. It is necessary to add (for example, refer nonpatent literature 1). This is contrary to the recent trend of reducing environmental impact. In addition, as a treatment method with reduced environmental load, a method of improving the anticorrosion effect by a method of adjusting water quality components has been proposed (for example, see Patent Document 1). In Patent Document 1, phosphoric acid, zinc salt, and acid consumption component are added, the total phosphoric acid concentration and the zinc concentration are each 1 mg / L or less, and the Langeria index at 30 ° C. is 1.2 or more. It is stated that the anticorrosion effect is exhibited.

JP 2009-299161 A

Kurita Water Treatment Chemicals Handbook Editorial Committee, “Pharmaceutical Handbook 3rd Edition”, 183 pages (1995)

However, in the method for improving the anticorrosive effect described in Patent Document 1, it is necessary to add an enormous amount of chemicals in order to make the calcium hardness, the silica concentration, and the Langeria index more than a certain value. Further, Patent Document 1 does not disclose the anticorrosion effect and the scale prevention effect in low hardness water quality.
Therefore, an anticorrosive agent that exhibits a high anticorrosive effect at a lower anticorrosive concentration in a low hardness cooling water system treatment is desired.
Accordingly, the present invention provides a metal anticorrosive for cooling water and a metal for cooling water capable of suppressing metal corrosion of heat exchangers, reaction kettles, pipes and the like in a low hardness cooling water system by addition of a low concentration chemical. It aims at providing the processing method of the cooling water system which uses a corrosion inhibitor.

As a result of diligent research, the present inventors have solved the above problem with a metal anticorrosive agent for cooling water containing phosphonotartaric acid, a phosphoric acid compound other than phosphonotartaric acid, and a zinc compound, which suppresses the anode reaction that causes metal corrosion. Has been found to be able to be solved, and the present invention has been completed. That is, the present invention is as follows.
[1] The phosphonotartaric acid, containing a phosphoric acid compound other than the phosphonotartaric acid and a zinc compound, which suppresses the anode reaction causing metal corrosion, the anode reaction causing the phosphonotartaric acid and the metal corrosion is inhibited, the content of the phosphono tartaric to the total of the phosphoric acid compound other than phosphono tartaric acid, metal corrosion inhibitor for cooling water is at least 35% by weight PO ₄ terms.
[2] The phosphoric acid compound other than the phosphonotartaric acid that suppresses the anode reaction that causes the metal corrosion is selected from the group consisting of orthophosphoric acid and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). The metal anticorrosive agent for cooling water according to the above [1], which is at least one phosphate compound.
[3] The metal corrosion inhibitor for cooling water according to the above [1] or [2], wherein the zinc compound is at least one zinc salt selected from the group consisting of zinc chloride and zinc sulfate.
[4] It further includes at least one AA / sulfone group-containing copolymer selected from the group consisting of the following AA / AMPS copolymer, AA / HAPS copolymer, and AA / AMPS / HAPS copolymer. The metal anticorrosive agent for cooling water according to any one of the above [1] to [3].
AA / AMPS copolymer: A copolymer of at least one of acrylic acid (AA) and its salt and acrylamidomethylpropanesulfonic acid (AMPS) and at least one of its salt AA / HAPS copolymer: Acrylic acid ( Copolymer of at least one of AA) and its salt and at least one of hydroxyallyloxypropane sulfonic acid (HAPS) and its salt AA / AMPS / HAPS copolymer: at least of acrylic acid (AA) and its salt A copolymer of at least one of acrylamide methyl propane sulfonic acid (AMPS) and its salt and at least one of hydroxyallyloxy propane sulfonic acid (HAPS) and its salt [5] at least one of the above The weight average molecular weight of the AA / sulfone group-containing copolymer is 500 to 50,000. The at least one AA / sulfone group-containing copolymer comprises a structural unit derived from AA and a salt thereof and a structural unit derived from AMPS, HAPS and a salt thereof in a molar ratio of 70:30 to 95: The metal corrosion inhibitor for cooling water according to the above [4], which is contained at a ratio of 5.
[6] Phosphonotartaric acid, a phosphoric acid compound other than the phosphonotartaric acid, and a zinc compound that suppresses the anode reaction that causes metal corrosion in a cooling water system having a calcium hardness of CaCO ₃ as 30 to 150 mg / L, A cooling water treatment method wherein the content of the phosphonotartaric acid with respect to the total of the phosphonotartaric acid and the phosphoric acid compound other than the phosphonotartaric acid is 35% by mass or more in terms of PO ₄ .
[7] Treatment of a cooling water system in which the metal corrosion inhibitor for cooling water according to any one of the above [1] to [5] is added to a cooling water system having a calcium hardness of ₃₀ to 150 mg / L as CaCO ₃ Method.
[8] The total concentration in terms of PO ₄ of the phosphonotartaric acid in the cooling water system and the phosphoric acid compound and zinc compound other than the phosphonotartaric acid, which suppresses the anode reaction causing the metal corrosion, is 0.00. The method for treating a cooling water system according to the above [7], wherein the metal corrosion inhibitor for cooling water is added to the cooling water system so as to be in the range of 05 to 5 mg / L.
[9] The above [7] or [7], wherein the metal anticorrosive for cooling water is added to the cooling water system so that the zinc element-concentrated concentration of the zinc compound in the cooling water system is 0.05 to 5 mg / L. The method for treating a cooling water system according to 8].
[10] The cooling water according to the above [4] or [5], so that the concentration in terms of solid content of the at least one AA / sulfone group-containing copolymer in the cooling water system is 1 to 10 mg / L. A cooling water system treatment method in which a metal anticorrosive is added to a cooling water system having a calcium hardness of ₃₀ to 150 mg / L as CaCO ₃ .

  ADVANTAGE OF THE INVENTION According to this invention, the metal corrosion inhibitor for cooling water which can suppress metal corrosion of a heat exchanger, a reaction kettle, piping, etc. by low concentration chemical | medical agent addition in the cooling water system of low hardness, and its metal for cooling water A method for treating a cooling water system using an anticorrosive agent can be provided.

FIG. 1 is a schematic diagram showing the configuration of a water flow test apparatus. FIG. 2 is a graph showing the results of the corrosion rate test of the example. FIG. 3 is a graph showing the results of the corrosion weight loss test of the example.

[Metal anticorrosive for cooling water]
The metal corrosion inhibitor for cooling water of the present invention contains phosphonotartaric acid, a phosphoric acid compound other than phosphonotartaric acid, and a zinc compound that suppresses the anode reaction that causes metal corrosion, and an anodic reaction that causes phosphonotartaric acid and metal corrosion. The content of phosphonotartaric acid with respect to the total of the phosphoric acid compounds other than the phosphonotartaric acid is 35% by mass or more in terms of PO ₄ . Thereby, metal corrosion of a heat exchanger, a reaction kettle, piping, etc. can be suppressed by low concentration chemical | medical agent addition. Hereinafter, the metal corrosion inhibitor for cooling water of the present invention will be described in detail.

(Phosphonotartaric acid)
The phosphonotartaric acid contained in the metal corrosion inhibitor for cooling water of the present invention is a compound that can be represented by the following general formula (I).

(Phosphoric acid compounds other than phosphonotartaric acid that suppress the anode reaction that causes metal corrosion)
When metals such as heat exchangers, reaction kettles and pipes emit electrons and are ionized, that is, when an anodic reaction occurs on the metal, metal corrosion occurs and proceeds. “A phosphoric acid compound other than phosphonotartaric acid that inhibits the anode reaction that causes metal corrosion” (hereinafter sometimes referred to as “anode reaction-suppressing phosphoric acid compound”) refers to inhibiting the occurrence and progression of the anode reaction. And phosphoric acid compounds other than phosphonotartaric acid.
Specifically, the anode reaction-suppressing phosphate compound is phosphoric acid that can suppress the anode reaction that causes metal corrosion compared to 2-phosphonobutane-1,2,3-tricarboxylic acid (PBTC) and hexametaphosphoric acid. It is a compound and means a phosphoric acid compound other than phosphonotartaric acid.

  The anode reaction-suppressing phosphate compound is preferably at least one phosphate compound selected from the group consisting of orthophosphoric acid and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP).

In addition, 2-phosphonobutane-1,2,3-tricarboxylic acid (PBTC), hexametaphosphoric acid etc. are mentioned as a phosphoric acid compound other than that with respect to phosphonotartaric acid and an anode reaction suppression phosphoric acid compound.
In contrast to these phosphonotartaric acid and anodic reaction-suppressing phosphate compounds, other phosphate compounds suppress metal corrosion in heat exchangers, reaction kettles and piping in low-hardness cooling water systems by adding low-concentration chemicals. From the viewpoint of, it is preferable that it is not contained in the metal corrosion inhibitor for cooling water of the present invention.

(Zinc compound)
Examples of the zinc compound contained in the metal corrosion inhibitor for cooling water of the present invention include zinc metaborate, zinc tetraborate, zinc fluoride, zinc bromide, zinc chloride, zinc iodide, zinc chlorite, Zinc chlorate, zinc perchlorate, zinc periodate, zinc carbonate, zinc carbonate hydroxide, zinc oxalate, zinc carbide, zinc formate, zinc acetate, zinc propionate, zinc butyrate, zinc valerate, zinc nitrate, zinc oxide Examples thereof include zinc nitrate, zinc oxide, zinc peroxide, zinc phosphide, zinc phosphinate, zinc diphosphate, zinc sulfide, zinc dithioate, zinc sulfite, zinc sulfate, zinc tetrathionate, and zinc pentathionate. One of these can be used alone, or two or more of these can be used in combination. From the viewpoint that metal corrosion of heat exchangers, reaction kettles, piping, and the like can be suppressed by addition of a low concentration of chemicals, preferred zinc compounds are at least one selected from the group consisting of zinc chloride and zinc sulfate. Zinc salt.

(AA / sulfone group-containing copolymer)
The metal corrosion inhibitor for cooling water according to the present invention contains at least one AA / sulfone group selected from the group consisting of AA / AMPS copolymer, AA / HAPS copolymer, and AA / AMPS / HAPS copolymer. A copolymer may further be included. Thereby, the metal corrosion inhibitory effect in the metal corrosion inhibitor for cooling water of this invention can further be improved.
Here, the AA / AMPS copolymer is a copolymer of at least one of acrylic acid (AA) and a salt thereof and at least one of acrylamidomethylpropane sulfonic acid (AMPS) and a salt thereof. The AA / HAPS copolymer is a copolymer of at least one of acrylic acid (AA) and a salt thereof and at least one of hydroxyallyloxypropane sulfonic acid (HAPS) and a salt thereof. Further, the AA / AMPS / HAPS copolymer includes at least one of acrylic acid (AA) and a salt thereof, at least one of acrylamidomethylpropane sulfonic acid (AMPS) and a salt thereof, and hydroxyallyloxypropane sulfonic acid. It is a copolymer with (HAPS) and at least one of its salts.

  From the viewpoint of further improving the metal corrosion inhibitory effect in the metal corrosion inhibitor for cooling water of the present invention, the weight average molecular weight of the at least one AA / sulfone group-containing copolymer is preferably 500 to 50,000. More preferably, it is 1,000-20,000. In addition, the said weight average molecular weight is a value of standard polyacrylic acid conversion by gel permeation chromatography (GPC method).

  From the viewpoint of further improving the metal corrosion inhibitory effect in the metal corrosion inhibitor for cooling water of the present invention, the proportion of the structural unit derived from AA and the structural unit derived from AMPS, HAPS and their salts is preferably mol. The ratio is 70:30 to 95: 5, and more preferably the molar ratio is 80:20 to 90:10.

(Other ingredients)
The metal corrosion inhibitor for cooling water of the present invention may contain components other than those described above as long as the effects of the present invention are not impaired. For example, a solvent such as water and other additives may be included.

(Content of each component)
In the metal corrosion inhibitor for cooling water of the present invention, the content of phosphonotartaric acid with respect to the total of phosphonotartaric acid and the anode reaction-suppressing phosphate compound is 35% by mass or more, preferably 45 to 90% by mass in terms of PO _4. More preferably, it is 50-75 mass%. When the content of phosphonotartaric acid with respect to the total of phosphonotartaric acid and anodic reaction-suppressing phosphate compound is less than 35% by mass, the addition of a low concentration of chemicals will suppress metal corrosion of heat exchangers, reaction kettles, piping, etc. I can't.

In addition, in a low hardness cooling water system, from the viewpoint of suppressing metal corrosion of heat exchangers, reaction kettles, pipes, etc. by addition of a low concentration chemical, the total amount of phosphate compound in the metal anticorrosive for cooling water of the present invention The total content of phosphonotartaric acid and the anodic reaction-suppressing phosphate compound is 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably in terms of PO _4. 100% by mass.

From the viewpoint that metal corrosion of heat exchangers, reaction kettles and pipes can be suppressed by addition of a low concentration of chemicals, the total amount of phosphonotartaric acid and anode reaction-suppressing phosphate compound is 100 parts by mass in terms of PO ₄ , The zinc equivalent of the zinc compound is preferably 10 to 500 parts by mass, more preferably 50 to 200 parts by mass, and still more preferably 80 to 140 parts by mass.

From the viewpoint that metal corrosion of heat exchangers, reaction kettles and pipes can be suppressed by addition of a low concentration of chemicals, the total amount of phosphonotartaric acid and anode reaction-suppressing phosphate compound is 100 parts by mass in terms of PO ₄ , The ratio of the AA / sulfone group-containing copolymer is preferably 10 to 1000 parts by mass, more preferably 80 to 500 parts by mass, and still more preferably 100 to 300 parts by mass.

  From the viewpoint that metal corrosion of heat exchangers, reaction kettles and pipes can be suppressed by adding a low concentration of chemicals, phosphonotartaric acid, anode in the total solid content of the metal anticorrosive for cooling water of the present invention The total amount of the reaction-suppressing phosphate compound, zinc compound, and AA / sulfone group-containing copolymer is preferably 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more. More preferably, it is 100 mass%.

[Cooling water treatment method]
The cooling water system treatment method of the present invention comprises adding a phosphonotartaric acid, an anode reaction-suppressing phosphate compound and a zinc compound to a cooling water system having a calcium hardness of ₃₀ to 150 mg / L as CaCO ₃ , and the phosphonotartaric acid and the anode reaction-suppressing phosphorus. the content of the phosphono tartaric to the total of the acid compound is added in an amount of 35 mass% or more PO ₄ terms. Thereby, metal corrosion of a heat exchanger, a reaction kettle, piping, etc. can be suppressed by low concentration chemical | medical agent addition. Hereinafter, the processing method of the cooling water system of this invention is demonstrated in detail.
In the cooling water treatment method of the present invention, an AA / sulfone group-containing copolymer may be further added. Here, the AA / sulfone group-containing copolymer is as described above.

In the cooling water system treatment method of the present invention, the phosphonotartaric acid, the anode reaction-suppressing phosphate compound, the zinc compound, and the AA / sulfone group-containing copolymer may be separately added to the cooling water system. Thereby, since only a required component can be added at a required timing, the addition amount of a chemical | medical agent can be suppressed more.
For example, when the phosphorus concentration (PO ₄ equivalent amount) in the cooling water system is measured continuously, regularly, or irregularly, and the measured value falls to a threshold value (for example, the lower limit value of the preferred concentration range described later) In addition, phosphonotartaric acid and an anodic reaction inhibiting phosphoric acid compound may be added.
Moreover, when the zinc compound concentration (Zn conversion amount) in the cooling water system is measured continuously, regularly, or irregularly, and the measured value is reduced to a threshold value (for example, a lower limit value of a suitable concentration range described later). In addition, a zinc compound may be added.
Further, the concentration of the AA / sulfone group-containing copolymer in the cooling water system is measured continuously, periodically, or irregularly, and the measured value is reduced to a threshold value (for example, a lower limit value of a suitable concentration range described later). In this case, an AA / sulfone group-containing copolymer may be added.

Further, in the cooling water system treatment method of the present invention, the above-described metal corrosion inhibitor for cooling water may be added to the cooling water system. Thereby, the installation number of a chemical | medical agent addition apparatus can be decreased.
For example, at least one or all of the phosphorus concentration (PO ₄ equivalent amount), the zinc compound concentration (Zn equivalent amount) in the cooling water system, and, if necessary, the concentration of the AA / sulfone group-containing copolymer, continuously, When measured regularly or irregularly, when at least one of the measured values falls to the respective threshold value (for example, the lower limit value of the preferred concentration range described later), a metal corrosion inhibitor for cooling water is added. Also good.

(Calcium hardness)
As described above, according to the cooling water system treatment method of the present invention, in a low hardness cooling water system, metal corrosion of heat exchangers, reaction kettles, pipes, and the like can be suppressed by addition of a low concentration chemical. Specifically, the low hardness cooling water system is a cooling water system having a calcium hardness of ₃₀ to 150 mg / L as CaCO ₃ .

(Amount of metal anticorrosive for cooling water added)
From the viewpoint of the effect of suppressing metal corrosion of heat exchangers, reaction kettles and piping by the phosphoric acid compound in the metal corrosion inhibitor for cooling water, PO ₄ of phosphonotartaric acid and the anode reaction-suppressing phosphoric acid compound in the cooling water system. The total concentration converted in (1) is preferably 0.05 to 5 mg / L, more preferably 0.1 to 3.0 mg / L, still more preferably 0.5 to 2 mg / L. As such, the metal corrosion inhibitor for cooling water of the present invention may be added to the cooling water system. Further, instead of the metal corrosion inhibitor for cooling water of the present invention, phosphonotartaric acid, anode reaction-suppressing phosphoric acid compound, or both may be added to the cooling water system so as to be within the above concentration range.

  In addition, from the viewpoint of the effect of suppressing metal corrosion of the heat exchanger, reaction kettle, piping, etc. by the zinc compound in the metal anticorrosive for cooling water, the concentration in terms of zinc element of the zinc compound in the cooling water system is preferably The metal for cooling water of the present invention so as to be 0.05 to 5 mg / L, more preferably 0.1 to 3.0 mg / L, and still more preferably 0.5 to 2 mg / L. An anticorrosive agent may be added to the cooling water system. Moreover, it may replace with the metal corrosion inhibitor for cooling water of this invention, and may add a zinc compound to the said cooling water system so that it may become in the said density | concentration range.

  Furthermore, from the viewpoint of the effect of suppressing metal corrosion of heat exchangers, reaction kettles, piping and the like by the at least one AA / sulfone group-containing copolymer in the metal anticorrosive for cooling water, the at least one in the cooling water system. The concentration in terms of solid content of the seed AA / sulfone group-containing copolymer is preferably 1 to 10 mg / L, more preferably 2 to 10 mg / L, still more preferably 2 to 7 mg / L. The metal corrosion inhibitor for cooling water of the present invention may be added to the cooling water system so as to be L. Moreover, it may replace with the metal corrosion inhibitor for cooling water of this invention, and may add the said at least 1 sort (s) AA / sulfone group containing copolymer to the said cooling water system so that it may become in the said density | concentration range.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, an Example does not limit this invention.

[Raw materials]
In this example, the following raw materials were used.
Phosphonotartaric acid aqueous solution (concentration: 14% by mass as PO ₄ )
HEDP aqueous solution (concentration: 55% by mass as PO ₄ )
Orthophosphoric acid aqueous solution (concentration: 73% by mass as PO ₄ )
PBTC (2-phosphonobutane-1,2,3-tricarboxylic acid) aqueous solution (concentration: 18% by mass as PO ₄ )
Hexametaphosphoric acid (concentration: 93% by weight as PO ₄ )
Zinc chloride aqueous solution (concentration: 20% by mass as Solid)
Polymer solution (copolymer of AA and AMPS, molar ratio (AA / AMPS): 89/11, weight average molecular weight: 6400, solvent: water, solid content concentration: 40% by mass)

[Production Example 1]
A phosphonotartaric acid aqueous solution, a HEDP aqueous solution, a zinc chloride aqueous solution, a polymer solution, and water were added to obtain an anticorrosive 1 having the composition shown in Table 1.
As in the first embodiment described below, the phosphorus compound in water (i.e., phosphono tartaric acid, HEDP, orthophosphoric acid, and the sum of PBTC) so that the concentration of the 2 mg / L in PO ₄ terms, anticorrosive 1 The concentration of each component constituting the anticorrosive 1 when added to water is as shown in Table 2.

[Production Examples 2-6 and Comparative Production Examples 1-9]
The anticorrosive agents 2 to 15 having the compositions shown in Table 1 were obtained by changing the type and addition amount of the phosphoric acid compound aqueous solution, the addition amount of zinc chloride, and the addition amount of the polymer.
Incidentally, the phosphorus compound in water (i.e., phosphono tartaric acid, HEDP, orthophosphoric acid, and the sum of PBTC) so that the concentration of the 2 mg / L in PO ₄ terms, in the case where the anticorrosive 2-15 was added to water, The concentration of each component constituting the anticorrosives 2 to 15 is as shown in Table 2.

[Example 1]
(Anti-corrosion test for sound surface)
A low carbon steel (JIS G3141SPSS-SB) having a dimension of 50 mm × 30 mm × 1 mm and a surface area of 0.31 dm ² was polished by # 400, and a test piece which was degreased with toluene was used as a sample. The weight of the sample was measured and used as the pre-test weight.
In a 1000 ml glass container, pure water is added in an amount obtained by subtracting the amount of each reagent described later from 1000 ml, and after adding sodium bicarbonate aqueous solution, magnesium sulfate aqueous solution, sodium chloride aqueous solution, calcium chloride aqueous solution and anticorrosive 1, a small amount of water is added. The pH was adjusted with an aqueous sodium oxide solution and an aqueous sulfuric acid solution to obtain test water. Table 3 shows the water quality of the test water of Example 1.

A 1000 ml glass container containing test water was set in a thermostatic chamber of a corrosion test apparatus maintained at 30 ° C., the test piece was screwed onto a rotating shaft and immersed, and rotated at 150 rpm. On the third day after the start of the test, it was replaced with new test water, and after 4 days, the test piece was taken out. The surface of the taken-out test piece was washed with an acid, the adhered corrosion product was removed and the weight after drying was measured, and the corresponding amount was taken as the post-test weight. Thereafter, the corrosion rate (mdd) was calculated from the weight change of the test piece according to the following formula (1), and the anticorrosion performance was evaluated. The evaluation results are shown in FIG.
Corrosion rate (mdd) = [weight before test (mg) −weight after test (mg)] / [surface area of test piece (dm ² ) × number of test days (days)] (1)

[Examples 2 to 6 and Comparative Examples 1 to 9]
(Anti-corrosion test for sound surface)
Test water was obtained in the same manner as in Example 1 except that the anticorrosive agents 2 to 15 were used in place of the anticorrosive agent 1. Table 3 shows the water quality of the test waters of Examples 2 to 6 and Comparative Examples 1 to 9.
Moreover, it replaced with the test water of Example 1, and evaluated the anticorrosion performance like Example 1 except having used the test water of Examples 2-6 and Comparative Examples 1-9. The evaluation results are shown in FIG.

[Example 7]
(Corrosion weight loss test for corroded surfaces)
First, two short tubes of carbon steel (STB-340) with a length of 10 cm and an inner diameter of 15 mm were prepared per condition, and after toluene degreasing, edging was performed with 5% by mass HCl, and this was sampled. It was. The weight of the short tube was measured with a balance and used as the weight before the test.
Subsequently, 100 L of a dilite tank was charged with pure water in an amount obtained by subtracting the amount of each reagent added, a sodium bicarbonate aqueous solution, a sodium silicate aqueous solution, a magnesium sulfate solution, a sodium chloride solution, a calcium chloride aqueous solution, a sodium sulfate aqueous solution, and After each addition of the anticorrosive agent 1, the pH was adjusted with a small amount of sodium hydroxide and carbon dioxide to obtain test water. Table 4 shows the water quality of the test water.

  The test water was transferred to the water test apparatus (FIG. 1), and continuous supply was performed so that the residence time was 120 hours.

  In the water flow test device 1 of FIG. 1, a test water tank 11 (capacity: 50 L) containing test water is provided. The test water in the test water tank is heated by the heater 13 whose heat generation temperature is controlled by the heater controller 12, and the temperature of the test water is maintained at 30 ° C. When the amount of water in the test water tank 11 becomes low, the test water is supplied from the makeup water tank (capacity: 50 L) 15 to the test water tank 11 using the water supply pump 14. When the amount of water in the test water tank 11 increases, the test water is discharged from the test water tank 11 via the line L1 as an overflow. Thereby, the amount of water in the test water tank 11 is kept constant.

  The test water discharged from the test tank 11 is divided into two lines L2 and L3. In the line L <b> 2, the test water that has passed through the circulating water pump 16 and the flow rate adjustment valve 17 is supplied to the air suction port 18. Air is mixed into the test water at the air inlet 18. The test water mixed with air passes through the carbon steel short pipe 19 and returns to the test water tank 11. The flow rate of the test water passing through the carbon steel short tube 19 is 0.3 m / s. On the other hand, in the line L 3, the test water that has passed through the circulating water pump 21 and the flow rate adjustment valve 22 passes through the carbon steel short pipe 23 and returns to the test water tank 11. The flow rate of the test water passing through the carbon steel short tube 23 is 0.3 m / s.

The above-mentioned short pipe was attached to the water test apparatus (FIG. 1), and the test was started. The short tube was pulled up 20 hours and 68 hours after the start of the test. The short pipe pulled up was washed with acid to remove corrosion products, and then the weight was measured and the corresponding amount was taken as the weight after the test. The weight change was calculated by the following formula and the anticorrosion performance was compared.
Corrosion loss (mg) = [Weight before test (mg) −Test weight after 68 hours (mg)] − [Weight before test (mg) −Test weight after 20 hours (mg)] (2)

[Examples 8 to 10 and Comparative Examples 10 to 13]
(Corrosion weight loss test for corroded surfaces)
Test water was obtained in the same manner as in Example 7 except that the anticorrosive agent 2, 4, 5, 7 to 10 was used instead of the anticorrosive agent 1. Table 4 shows the test water quality of Examples 8 to 10 and Comparative Examples 10 to 13.
Moreover, it replaced with the test water of Example 7, and evaluated anticorrosion performance like Example 7 except having used the test water of Examples 8-10 and Comparative Examples 10-13. The evaluation results are shown in FIG.

[Evaluation results]
The evaluation results of the corrosion rate test and the corrosion weight loss test are shown in FIGS.
From Table 3, Table 4, FIG. 2 and FIG. 3, the metal anticorrosive for cooling water contains phosphonotartaric acid, an anode reaction-suppressing phosphate compound and a zinc compound, and the phosphonotartaric acid and the anode reaction-suppressing phosphate compound It was found that when the content of the phosphonotartaric acid with respect to the total is 35% by mass or more, the corrosion rate of the metal can be reduced by adding a low concentration of the chemical, and further, the weight loss of the metal can be reduced by adding the low concentration of the chemical. .

DESCRIPTION OF SYMBOLS 1 Water flow test apparatus 11 Test water tank 12 Heater controller 13 Heater 14 Water supply pump 15 Supply water tank 16, 21 Circulating water pump 17, 22 Flow rate adjustment valve 18 Air inlet 19, 23 Carbon steel short pipe L1-L3 line

Claims (10)

Phosphonotartaric acid,
A phosphoric acid compound other than the phosphonotartaric acid, comprising a phosphoric acid compound other than the phosphonotartaric acid and a zinc compound, which suppresses the anode reaction causing the metal corrosion, and which suppresses the anode reaction causing the metal corrosion to the phosphonotartaric acid. the content of the phosphono tartaric acid, metal corrosion inhibitor for cooling water is at least 35% by weight PO ₄ in terms of the total of the compound.   At least one selected from the group consisting of orthophosphoric acid and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), wherein the phosphoric acid compound other than phosphonotartaric acid, which suppresses the anode reaction that causes the metal corrosion, The metal anticorrosive agent for cooling water according to claim 1, which is a phosphoric acid compound.   The metal corrosion inhibitor for cooling water according to claim 1 or 2, wherein the zinc compound is at least one zinc salt selected from the group consisting of zinc chloride and zinc sulfate. The at least one AA / sulfone group-containing copolymer selected from the group consisting of the following AA / AMPS copolymer, AA / HAPS copolymer, and AA / AMPS / HAPS copolymer: The metal anticorrosive agent for cooling water of any one of -3.
AA / AMPS copolymer: A copolymer of at least one of acrylic acid (AA) and its salt and acrylamidomethylpropanesulfonic acid (AMPS) and at least one of its salt AA / HAPS copolymer: Acrylic acid ( Copolymer of at least one of AA) and its salt and at least one of hydroxyallyloxypropane sulfonic acid (HAPS) and its salt AA / AMPS / HAPS copolymer: at least of acrylic acid (AA) and its salt Copolymer of one kind, at least one of acrylamidomethylpropane sulfonic acid (AMPS) and a salt thereof, and at least one of hydroxyallyloxypropane sulfonic acid (HAPS) and a salt thereof   The weight average molecular weight of the at least one AA / sulfone group-containing copolymer is 500 to 50,000, and the at least one AA / sulfone group-containing copolymer is derived from AA and a salt thereof. The metal anticorrosive agent for cooling water according to claim 4 comprising AMPS, HAPS, and structural units derived from salts thereof in a molar ratio of 70:30 to 95: 5. Phosphorotartaric acid, a phosphoric acid compound other than phosphonotartaric acid, and a zinc compound that suppresses the anode reaction that causes metal corrosion in a cooling water system having a calcium hardness of CaCO ₃ of 30 to 150 mg / L. A cooling water treatment method wherein the content of the phosphonotartaric acid relative to the total of the phosphoric acid compound other than the phosphonotartaric acid is 35% by mass or more in terms of PO ₄ . As the calcium hardness CaCO _3, the cooling water system is 30~150mg / L, the processing method of the cooling water system of adding cooling water metal corrosion inhibitor according to any one of claims 1 to 5. Wherein said phosphono tartaric in cooling the water system, the causative inhibit anodic reaction of metal corrosion, said phosphate compound other than phosphono tartaric concentration of total converted by PO ₄ 0.05 to 5 mg / L The processing method of the cooling water system according to claim 7, wherein the metal corrosion inhibitor for cooling water is added to the cooling water system.   The cooling according to claim 7 or 8, wherein the metal anticorrosive for cooling water is added to the cooling water system so that the zinc element-concentrated concentration of the zinc compound in the cooling water system is 0.05 to 5 mg / L. Water treatment method. The metal anticorrosive agent for cooling water according to claim 4 or 5, so that the concentration in terms of solid content of the at least one AA / sulfone group-containing copolymer in the cooling water system is 1 to 10 mg / L. A method for treating a cooling water system, which is added to a cooling water system having a calcium hardness of ₃₀ to 150 mg / L as CaCO ₃ .