JP2013204147A - Agent for suppressing corrosion of iron and copper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agent capable of suppressing corrosion of iron and copper due to water in a water system flow path while minimizing the usage of an iron corrosion inhibitor and a copper corrosion inhibitor.SOLUTION: An agent for suppressing corrosion of iron and copper due to water in a water system flow path includes an iron corrosion inhibitor, a copper corrosion inhibitor, and at least one silica component selected from a group consisting silicic acid and silicate. In the agent, it is preferable that a ratio of a weight of the iron corrosion inhibitor: a weight of the copper corrosion inhibitor: an SiOequivalent weight of the silica component is 10-40:1-3:50 or higher.

Description

  The present invention relates to a chemical for suppressing corrosion of iron and copper by water in an aqueous channel.

  Circulating water in the circulating water system channel generally contains corrosive ions such as chloride ions and sulfate ions. When the water in the circulating water evaporates, the concentration of corrosive ions in the circulating water increases. Along with this, metal corrosion is promoted in various piping systems (lines).

  Conventionally, as a chemical | medical agent for suppressing the corrosion of the metal produced by the influence of a water | moisture content, the water treatment agent containing a silica is well-known (patent document 1). Moreover, in order to suppress the corrosion of the metal used in an aqueous channel, an iron anticorrosive and a copper anticorrosive are used.

Japanese Patent Laid-Open No. 2003-159597

  The water treatment agent of Patent Document 1 is intended to suppress metal corrosion using silica, but the anticorrosive effect of silica is not sufficient. Further, the iron anticorrosive and the copper anticorrosive have a high concentration necessary for exhibiting the anticorrosive effect, and it is difficult to achieve resource saving and cost reduction of the chemical.

  An object of this invention is to provide the chemical | medical agent which can suppress the corrosion of iron and copper by the water in a water-system flow path, suppressing the usage-amount of an iron anticorrosive and a copper anticorrosive.

  The present invention relates to corrosion of iron and copper by water in an aqueous channel, comprising an iron anticorrosive, a copper anticorrosive, and at least one silica component selected from the group consisting of silicic acid and silicate. It is related with the medicine for controlling.

In the above agent, the ratio of the weight of the iron anticorrosive agent: the weight of the copper anticorrosive agent: the weight of the silica component in terms of SiO ₂ is preferably 30 to 95: 1 to 3:50 or more.

  ADVANTAGE OF THE INVENTION According to this invention, the chemical | medical agent which can suppress the corrosion of iron and copper by the water in an aqueous channel can be provided, suppressing the usage-amount of an iron anticorrosive and a copper anticorrosive.

It is a graph which shows the result of having performed the corrosion test of iron or copper, changing the density | concentration of an iron anticorrosive or a copper anticorrosive, when the silicic acid density | concentration in test water is 50 mg / L. It is a graph which shows the result of having performed the corrosion test of iron or copper by changing the silicic acid density | concentration in test water in absence or presence of an iron anticorrosive or a copper anticorrosive. It is a graph which shows another result which changed the silicic acid concentration in test water in the presence of an iron corrosion inhibitor or a copper corrosion inhibitor, and performed an iron or copper corrosion test.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the “chemical for suppressing corrosion of iron and copper” may be referred to as “corrosion inhibitor”.
The chemical | medical agent of this invention is a chemical | medical agent for suppressing the corrosion of iron and copper by the water in a water-system flow path, Comprising: It selects from the group which consists of an iron corrosion inhibitor, a copper corrosion inhibitor, a silicic acid, and a silicate. And at least one silica component.

[Water channel]
An example of the water channel is a circulating water channel. The water system flow path includes, for example, a pipe line, and may further include a cooling tower such as an open cooling tower and a closed cooling tower, a heat exchanger, and the like. As an example of a water system flow path including a pipe line, a cooling tower, and a heat exchanger, a cooling tower for cooling circulating water, a heat exchanger, and a circulation for supplying cooled circulating water from the cooling tower to the heat exchanger A water system flow path provided with a water supply line and a circulating water recovery line for recovering the circulating water from the heat exchanger to the cooling tower can be mentioned.

[Iron corrosion inhibitor]
It does not specifically limit as an iron anticorrosive used by this invention, A well-known iron anticorrosive can be used. Examples of the iron anticorrosive include phosphonic acid compounds, (meth) acrylic acid polymers, and polymerized phosphoric acid compounds. An iron anticorrosive may be used individually by 1 type, or may use 2 or more types together.

  Examples of the phosphonic acid compounds include 2-phosphonobutane-1,2,4-tricarboxylic acid, phosphonoethane-1,2-dicarboxylic acid, phosphonobutane-1,2,3,4-tetracarboxylic acid, 1-hydroxyethylidene- Phosphonic acid such as 1,1-diphosphonic acid, and sodium 2-phosphonobutane-1,2,4-tricarboxylate, tetrasodium phosphonoethane-1,2-dicarboxylate, phosphonobutane-1,2,3,4-tetracarboxylic acid Examples include phosphonates such as hexasodium acid, trisodium 1-hydroxyethylidene-1,1-diphosphonate, and tetrasodium 1-hydroxyethylidene-1,1-diphosphonate.

  Examples of the (meth) acrylic acid polymer include (meth) acrylic acid homopolymer, 2-acrylamido-2-methylpropanesulfonic acid / acrylic acid copolymer, and the like.

  Examples of the polymerized phosphoric acid compound include polymerized phosphoric acid such as tripolyphosphoric acid and hexametaphosphoric acid, and polymerized phosphate such as sodium tripolyphosphate and sodium hexametaphosphate.

[Copper anticorrosive]
It does not specifically limit as a copper anticorrosive used by this invention, A well-known copper anticorrosive can be used. Examples of the copper anticorrosive include azole compounds such as 1,2,3-benzotriazole and tolyltriazole. A copper anticorrosive may be used individually by 1 type, or may use 2 or more types together.

[Silica component]
The silica component used in the present invention is at least one selected from the group consisting of silicic acid and silicate. Examples of the silicate include alkali metal silicates such as sodium silicate and potassium silicate, and alkaline earth metal silicates such as calcium silicate and magnesium silicate. Silicates may be used alone or in combination of two or more. The silica component may be used in a powder state or in an aqueous solution state.

[Other ingredients]
In addition to the above components, the corrosion inhibitor of the present invention includes a hardness dispersant such as a maleic acid polymer, a pH adjuster such as potassium hydroxide and sodium hydroxide, and a tracer such as a lithium salt (aqueous system). A component for measuring the concentration of the corrosion inhibitor of the present invention added to the water in the flow path.The concentration of the corrosion inhibitor is indirectly measured by measuring the concentration of the tracer), hypochlorous acid Bactericides such as sodium acid and hypobromite, and solvents such as water may be included.

[Production method]
The corrosion inhibitor of the present invention can be produced by mixing the above components. Moreover, you may manufacture as a 2 part type chemical | medical agent which consists of the 1st part containing a silica component, and the 2nd part containing components other than a silica component. In the corrosion inhibitor of the present invention, the ratio of the weight of the iron anticorrosive agent: the weight of the copper anticorrosive agent: the weight of the silica component in terms of SiO ₂ is preferably 10 to 40: 1 to 3:50 or more, and preferably 15 to 35. : It is more preferable that it is 1.5-2.5: 50 or more. When the weight ratio of the content of these components is within the above range, it is easy to obtain a high corrosion inhibitory effect while suppressing the use amounts of the iron anticorrosive and the copper anticorrosive.

Furthermore, since the scale caused by the silica component is less likely to occur when added to the water in the aqueous channel, in the corrosion inhibitor of the present invention, the weight of the iron anticorrosive: the weight of the copper anticorrosive: The ratio of the weight in terms of SiO ₂ is preferably 10 to 40: 1 to 3:50 to 250, and more preferably 15 to 35: 1.5 to 2.5: 50 to 250.

The ratio of the total of the weight of the iron corrosion inhibitor, the weight of the copper corrosion inhibitor, and the weight of the silica component in terms of SiO _{2 to the} weight of the corrosion inhibitor of the present invention is preferably 20 to 80% by weight, and 30 to 70%. More preferably, it is% by weight.

[how to use]
The corrosion inhibitor of this invention is used in order to suppress the corrosion of iron and copper by the water in an aqueous channel. Specifically, it is used to suppress corrosion of iron and copper constituting at least a part of the water-based flow path. In this case, the corrosion inhibitor is added to the water in the aqueous channel.

The amount of the corrosion inhibitor added is such that the concentration of SiO _{2 in} all silica components contained in the water in the aqueous channel is 100 mg / L or more, the concentration of the iron corrosion inhibitor is 10 to 40 mg / L, and the copper corrosion inhibitor The concentration is preferably set to 1 to 3 mg / L, the SiO ₂ equivalent concentration of all the silica components is 100 mg / L or more, the concentration of the iron anticorrosive is 15 to 35 mg / L, and the copper anticorrosive It is more preferable to set the concentration to be 1.5 to 2.5 mg / L. When the addition amount of the corrosion inhibitor is set within the above range, it is easy to obtain a high corrosion inhibitory effect while suppressing the use amounts of the iron anticorrosive and the copper anticorrosive.

Furthermore, the addition amount of the corrosion inhibitor is preferably set so that the SiO ₂ equivalent concentration of all silica components contained in the water in the aqueous channel is 300 mg / L or less. When the SiO ₂ equivalent concentration of the silica component is 300 mg / L or less, a scale caused by the silica component is difficult to occur.
The corrosion inhibitor may be added continuously to the water in the aqueous channel or may be added intermittently.

  Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.

[Corrosion test]
In order to evaluate the corrosion inhibitory effect of the corrosion inhibitor of the present invention, a corrosion test was conducted in accordance with the rotation method specified in JIS K 0100-1990 (industrial water corrosion test method). That is, two iron test pieces and two copper test pieces were alternately attached to the test piece holder and immersed in test water filled in a 1 L beaker. The beaker was placed in a thermostat and the temperature of the test water was kept at 37 ° C. A test piece holder was attached to a motor rotating shaft, and the test piece was rotated at 150 rpm. For 6 days, the test water was continuously supplied to the beaker using a microtube pump at a flow rate of 50 mL / hour. The amount of corrosion (mdd) is calculated from the following formula:
Corrosion amount (mdd) = X / (Y × Z)
(Wherein, X represents the weight loss (mg) of the test piece before and after the test, Y represents the surface area (dm ² ) of the test piece, and Z represents the number of days of the test (days)).
Calculated by For iron, if the corrosion amount (mdd) is 200 or less, it is judged that the corrosion inhibition effect is good. For copper, if the corrosion amount (mdd) is 1.5 or less, the corrosion inhibition effect is good. It was judged that.

The details of the test piece used are as follows.
Iron test piece (SS400, dimensions: 1.6mm x 30mm x 30mm, whole surface # 400 polished, 4mmφ through hole at the center of the main surface)
Copper test piece (C1220P, dimensions: 1.6 mm × 30 mm × 30 mm, entire surface # 400 polished, 4 mmφ through hole at the center of the main surface)
The details of the test water will be described in each example and comparative example.

[Examples 1 and 2, Comparative Examples 1 to 5]
Test water was prepared by adding silicic acid and the anticorrosive mixture shown in Table 2 to the soft water 1 having the following water quality in the addition amount shown in Table 1. A corrosion test was conducted using this test water. The results are shown in Table 1 and FIGS.
Water quality of soft water 1: chloride ion 200 mg / L, sulfate ion 200 mg / L, acid consumption (pH 4.8) 300 mg CaCO ₃ / L, silicic acid 50 mg / L (SiO ₂ equivalent), hardness 0 mg CaCO ₃ / L

注）ケイ酸についてはＳｉＯ_２換算濃度

Note) SiO ₂ in terms of concentration for silicate

Details of each component in Table 2 are as follows.
Iron anticorrosive 1: Mixture of phosphonoethane-1,2-dicarboxylic acid tetrasodium and phosphonobutane-1,2,3,4-tetracarboxylic acid hexasodium Iron anticorrosive 2: 2-acrylamido-2-methylpropanesulfonic acid Acrylic acid copolymer Copper anticorrosive: 1,2,3-benzotriazole pH adjuster 1: 48 wt% potassium hydroxide pH adjuster 2: 25 wt% sodium hydroxide Tracer: Lithium salt

[Examples 3 to 4, Comparative Example 6]
Test water was prepared by adding silicic acid and the anticorrosive mixture shown in Table 2 to the soft water 2 having the following water quality in the addition amount shown in Table 3. A corrosion test was conducted using this test water. The results are shown in Table 3 and FIG.
Water quality of soft water 2: chloride ion 140 mg / L, sulfate ion 140 mg / L, acid consumption (pH 4.8) 120 mg CaCO ₃ / L, silicic acid 50 mg / L (in terms of SiO ₂ ), hardness 0 mg CaCO ₃ / L

注）ケイ酸についてはＳｉＯ_２換算濃度

Note) SiO ₂ in terms of concentration for silicate

[Evaluation]
(1) Iron corrosion test As can be seen from the results of Comparative Examples 1 to 3 (Table 1, Fig. 1 (a)), when the concentration of silicic acid in the test water is a low value of 50 mg / L, an iron corrosion inhibitor Even when added to a total concentration of 24.8 mg / L, the amount of iron corrosion was almost the same as when no iron corrosion inhibitor was added. The iron corrosion amount was reduced to 49 mdd only after the iron corrosion inhibitor was added to a total concentration of 49.6 mg / L.

  From the results of Comparative Examples 1, 4, and 5 (Table 1, FIG. 2 (a)), in the absence of an iron anticorrosive, even if the silicic acid concentration is increased from 50 mg / L to 150 mg / L, sufficient corrosion is caused. No inhibitory effect was seen. In contrast, from the results of Comparative Example 2 and Examples 1 and 2 (Table 1, FIG. 2 (a)), in the presence of 24.8 mg / L of an iron anticorrosive, the silicic acid concentration was changed from 50 mg / L to 100 mg / L. A sufficient corrosion inhibitory effect was obtained by increasing to L or 150 mg / L. At this time, the amount of decrease in the amount of iron corrosion caused by increasing the concentration of silicic acid was larger than that in the absence of iron corrosive agent. For example, when the concentration of silicic acid is increased from 50 mg / L to 100 mg / L, the amount of decrease in the iron corrosion amount was 121 mdd in the absence of the iron corrosion agent, whereas 24.8 mg / L of the iron corrosion inhibitor. In the presence, it showed a large value of about 237 mdd, about twice as large. In addition, when the silicic acid concentration was increased from 100 mg / L to 150 mg / L, the amount of decrease in the iron corrosion amount was 75 mdd in the absence of the iron corrosion agent, whereas 24.8 mg / L of the iron corrosion inhibitor. In the presence, a large value of 160 mdd or more, which was twice or more, was shown. Therefore, it turns out that a silicic acid and an iron anticorrosive acted synergistically and sufficient corrosion inhibitory effect was acquired.

  This tendency is particularly strong in the case of Comparative Example 6 and Examples 3 and 4 (Table 3, FIG. 3 (a)), and the silicic acid concentration is 50 mg / L in the presence of 24.8 mg / L of an iron anticorrosive. When the amount was increased from 100 to 100 mg / L, the amount of iron corrosion decreased rapidly.

  As described above, it has been found that if the silicic acid concentration is 100 mg / L or more, even if the concentration of the iron anticorrosive is a low value of 24.8 mg / L, a sufficient corrosion inhibiting effect can be obtained.

(2) About copper corrosion test As can be seen from the results of Comparative Examples 1 to 3 (Table 1, FIG. 1 (b)), when the concentration of silicic acid in the test water is 50 mg / L, the copper corrosion inhibitor is 2 mg / L. By adding so as to have a concentration of L or more, a sufficient corrosion inhibiting effect was obtained.

  From the results of Comparative Examples 1, 4, and 5 (Table 1, FIG. 2 (b)), in the absence of a copper anticorrosive, the amount of corrosion increased as the silicic acid concentration was increased from 50 mg / L to 150 mg / L. However, as the results of Comparative Example 2 and Examples 1 and 2 (Table 1, FIG. 2 (b)) show, a sufficient corrosion inhibitory effect can be obtained by adding 2 mg / L of copper anticorrosive. It was.

  Similarly, in the case of Comparative Example 6 and Examples 3 and 4 (FIG. 3B), 2 mg / L of copper anticorrosive should be added even if the silicic acid concentration is increased from 50 mg / L to 150 mg / L. Thus, a sufficient corrosion inhibiting effect was obtained.

  As described above, it has been found that even when the concentration of the copper anticorrosive is a low value of 2 mg / L, a sufficient corrosion inhibiting effect can be obtained.

(3) Summary From (1) and (2), 24.8 mg / L iron corrosion inhibitor, 2 mg / L copper corrosion inhibitor, and 50 against soft water containing 50 mg / L (SiO ₂ equivalent) of silicic acid. or by adding silica component of 100mg / L (SiO ₂ conversion), it was found that a sufficient corrosion inhibiting effect is obtained.

Claims (2)

  In order to suppress corrosion of iron and copper by water in an aqueous channel, including an iron anticorrosive, a copper anticorrosive, and at least one silica component selected from the group consisting of silicic acid and silicate Drugs. In the medicament, the weight of the iron corrosion inhibitor: the weight of the copper anticorrosive ratio of SiO ₂ reduced weight of the silica component is 10 to 40: 1 to 3: more than 50 in the drug according to claim 1.

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