JP2012201967A - Method for inhibiting corrosion of copper member and corrosion inhibitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively inhibit corrosion of a copper member such as a copper tube contacting a water system, e.g. a cooling water system, by using a small amount of chemical.SOLUTION: A method for inhibiting corrosion of the copper member comprises adding a compound represented by formula (1) (wherein R is alkyl group or alkenyl group; and X, Y and Z are each independently hydrogen atom, alkyl group, benzyl group, hydroxyalkyl group or carboxyalkyl group, provided that the hydroxyalkyl group or the carboxyalkyl group may form a salt) and an azole corrosion inhibitor for copper to the water system contacting the copper member.

Description

  The present invention relates to a technique for inhibiting corrosion of a copper-based member in contact with water. More specifically, the present invention relates to a technique for suppressing corrosion of a copper-based member such as a copper pipe in contact with an aqueous system such as a cooling water system using a chemical.

  Copper has a characteristic of excellent thermal conductivity, and is widely used for heat transfer tubes such as air conditioners and heat exchangers. However, these copper-based members in contact with water systems have a problem of corrosion. In particular, the efficiency of recent equipment is increasing, and the thickness of copper pipes used in heat exchangers is extremely thin. Therefore, the occurrence of corrosion has a high risk of lead-through leakage of copper pipes. . Therefore, it is indispensable for stable operation and long life of the equipment that the copper-based member does not corrode and does not proceed with the generated corrosion.

  In general, the corrosion reaction proceeds by a pair of metal elution reaction (anode reaction) and oxidant reduction reaction (cathode reaction). For example, in a pH neutral to weakly alkaline environment such as cooling water, dissolved oxygen in the water becomes a catalyst for the cathode reaction as an oxidizing agent.

Conventionally, in order to suppress corrosion of a copper-based member in contact with an aqueous system, water treatment in which an azole-based anticorrosive agent for copper such as benzotriazole, tolyltriazole, or mercaptobenzothiazole is added to the aqueous system has been performed (for example, Patent Documents). 1, 2). It is known that by adding these azole copper anticorrosives to an aqueous system such as a cooling water system, it exhibits an excellent corrosion-inhibiting effect on copper-based members in contact with the aqueous system, and is widely applied. .
That is, the azole-type anticorrosive agent for copper is excellent in the effect of suppressing the metal elution reaction (anode reaction) in the corrosion reaction, and exhibits a good corrosion-inhibiting effect.

  However, even when an azole copper anticorrosive is added, the occurrence and progression of corrosion may not be sufficiently suppressed. For example, an anti-corrosion film made of an azole copper anti-corrosion agent is locally destroyed for some reason, such as excessive addition of an oxidizing agent, and the elution of copper from the destroyed part of the film can be suppressed by the azole copper anti-corrosion agent. As a result, the film destruction part becomes a local anode, and corrosion may proceed.

JP-A-5-222555 Japanese Patent Laid-Open No. 6-212459

  The present invention solves the above-mentioned conventional problems, and uses a small amount of chemicals for a copper-based member such as a copper pipe in contact with an aqueous system such as a cooling water system, and effectively suppresses the occurrence of corrosion and It is an object to provide a corrosion inhibitor.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor is that the specific compound represented by the following general formula (1) is excellent in the cathode reaction suppression effect of a copper-based member in contact with an aqueous system, and this compound In addition, the present inventors have found that the corrosion of copper-based members can be effectively suppressed with the addition of a small amount of chemicals by the combined use with an azole-based anticorrosive for copper having an excellent anode reaction suppression effect.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] A method for inhibiting corrosion of a copper-based member, comprising adding a compound represented by the following formula (1) and an azole-based anticorrosive for copper to an aqueous system in contact with the copper-based member.

(In the formula (1), R represents an alkyl group or an alkenyl group, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group, a benzyl group, a hydroxyalkyl group, or a carboxyalkyl group, and a hydroxyalkyl group. The carboxyalkyl group may form a salt.)

[2] The method for inhibiting corrosion of a copper-based member according to [1], wherein the alkyl group or alkenylkill group of R in the formula (1) has 6 to 18 carbon atoms.

[3] X, Y, Z in the formula (1) is selected from a hydrogen atom, a hydroxyethyl group, a carboxymethyl group, a hydroxyethyl group forming a salt, and a carboxymethyl group forming a salt. The method for inhibiting corrosion of a copper-based member according to [1] or [2].

[4] In the formula (1), R is an alkyl group having 11 carbon atoms, X is a hydrogen atom, Y is a hydroxyethyl group, and Z is a carboxymethyl group or a carboxymethyl group forming a salt. [3] The method for inhibiting corrosion of a copper-based member according to claim 1.

[5] The method for inhibiting corrosion of a copper-based member according to any one of [1] to [4], wherein the azole-based copper anticorrosive is benzotriazole.

[6] The method for inhibiting corrosion of a copper-based member according to any one of [1] to [5], wherein the aqueous system is an aqueous system to which an oxidizing slime control agent is added.

[7] A corrosion inhibitor for suppressing corrosion of a copper-based member in contact with an aqueous system, comprising a compound represented by the following (1) and an anti-corrosive agent for azole-based copper, Corrosion inhibitor.

(In the formula (1), R represents an alkyl group or an alkenyl group, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group, a benzyl group, a hydroxyalkyl group, or a carboxyalkyl group, and a hydroxyalkyl group. The carboxyalkyl group may form a salt.)

[8] The corrosion inhibitor for copper-based members according to [7], wherein the alkyl group or alkenylkill group of R in the formula (2) has 6 to 18 carbon atoms.

[9] X, Y and Z in the formula (1) are selected from a hydrogen atom, a hydroxyethyl group, a carboxymethyl group, a hydroxyethyl group forming a salt, and a carboxymethyl group forming a salt. The corrosion inhibitor for copper-based members according to [7] or [8].

[10] R in the formula (1) is an alkyl group having 11 carbon atoms, X is a hydrogen atom, Y is a hydroxyethyl group, and Z is a carboxymethyl group or a carboxymethyl group forming a salt [9]. The corrosion inhibitor for copper-based members according to 1.

[11] The corrosion inhibitor for copper-based members according to any one of [7] to [10], wherein the azole copper anticorrosive is benzotriazole.

In general, the corrosion reaction proceeds by a pair of metal elution reaction (anode reaction) and oxidant reduction reaction (cathode reaction).
Therefore, a coating with excellent corrosion resistance and durability is formed on the surface of a copper-based member by adding a chemical having an excellent anodic reaction suppressing effect and a chemical having an excellent cathodic reaction-suppressing effect to an aqueous system in contact with a copper-based member such as a copper tube. Thus, the occurrence and progression of corrosion can be effectively suppressed.

  The compound represented by the general formula (1) used in the present invention (hereinafter sometimes referred to as “compound (1)”) is excellent in the effect of suppressing the cathode reaction of the copper-based member, while the anti-corrosion for azole-based copper. Since the agent is excellent in the anode reaction suppressing effect, according to the present invention, an excellent anticorrosive effect can be obtained by adding the compound (1) and the azole copper anticorrosive to the aqueous system.

  Therefore, according to the present invention, it is possible to effectively suppress the corrosion of the copper-based member in contact with the aqueous system, to stably operate the water-based equipment for a long period of time, and to greatly extend its life. .

  DESCRIPTION OF EMBODIMENTS Embodiments of a method for inhibiting corrosion of a copper-based member and a corrosion inhibitor according to the present invention will be described in detail below.

  In the present invention, the following compound (1) and an azole copper anticorrosive are added to the aqueous system in contact with the copper-based member.

<Compound (1)>
The compound (1) according to the present invention is a compound represented by the following formula (1).

(In the formula (1), R represents an alkyl group or an alkenyl group, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group, a benzyl group, a hydroxyalkyl group, or a carboxyalkyl group, and a hydroxyalkyl group. The carboxyalkyl group may form a salt.)

  The carbon number of the alkyl group or alkenyl group of R in the above formula (1) is preferably 6 to 18, particularly 11.

  X, Y, and Z each independently form a hydrogen atom, a hydroxyethyl group, or a carboxymethyl group (hydroxyethyl group or carboxymethyl group is a salt such as an alkali metal salt such as sodium salt or potassium salt). It is preferable that

  As the compound (1), R in the formula (1) is an alkyl group having 11 carbon atoms, X is a hydrogen atom, Y is a hydroxyethyl group, and Z is a carboxymethyl group or a carboxymethyl group forming a salt. Some are particularly preferred.

  A compound (1) may be used individually by 1 type, and may use 2 or more types together.

<Azole copper anticorrosive>
Examples of the azole copper anticorrosive include tolyltriazole, benzotriazole, mercaptobenzothiazole and their derivatives, and benzotriazole is particularly preferred.

  These azole copper anticorrosives may be used alone or in combination of two or more.

<Amount added to water system>
When adding the compound (1) and the azole copper anticorrosive used in the present invention to the aqueous system, it is necessary to adjust the concentration to obtain an optimal effect depending on the water quality of the water system to be treated, the surface area of the copper-based member, and the like. it can.

  The concentration of compound (1) added to the aqueous system is usually in the range of 0.2 to 100 mg / L, preferably 0.5 to 20 mg / L.

  The concentration of the azole copper anticorrosive added to the aqueous system is usually in the range of 0.2 to 20 mg / L, preferably 0.5 to 10 mg / L.

  Although there is no restriction | limiting in particular about the correlation of the addition density | concentration of a compound (1) and an azole-type copper anticorrosive, The addition density | concentration of a compound (1) is 0.1-10 with respect to the addition concentration of an azole-type copper anticorrosive. It is preferable to use so that it may become about a weight times.

<Conditions of target water system>
The aqueous temperature (water temperature) at the time of treatment according to the present invention (that is, at the time of addition of compound (1) and azole copper anticorrosive) is not particularly limited as long as the effect of the present invention can be obtained. However, the range of 5-60 degreeC is preferable. Moreover, as a pH of the aqueous system at the time of a process, a process is normally performed in the range of 4-11.

  The flow rate of the aqueous system during the treatment according to the present invention is not particularly limited as long as the effect of the present invention can be obtained, but the treatment is usually performed in the range of 0.1 to 2 m / sec. Although it is possible to perform the treatment even in a stationary condition, in this case, since the diffusion of the added drug to the surface of the copper-based member becomes rate-limiting, measures such as increasing the concentration of addition are required.

  There is no restriction | limiting in particular in the addition method to the aqueous system of a compound (1) and an azole type copper anticorrosive agent, It is also possible to add each component separately, Compound (1) and an azole type copper anticorrosive agent beforehand It is also possible to add to a water system as a water treatment agent blended in one agent.

  In the present invention, water treatment agents other than the compound (1) and the azole copper anticorrosive agent, for example, anticorrosive agents, scale inhibitors, dispersants, slime control agents, peeling, as long as the effects of the present invention are not impaired. Agents, antifoaming agents, surfactants, chelating agents and the like can be used in combination.

  In particular, the method for inhibiting corrosion of a copper-based member of the present invention has a feature that it can exhibit a good corrosion-inhibiting effect even in an aqueous system in which an oxidizing slime control agent is added to the applied aqueous system. An oxidizing slime control agent may be added to the applied water system. Such oxidizing slime control agents include hypochlorous acid and salts thereof, hypobromite and salts thereof, chlorinated isocyanuric acid and salts thereof, such as chlorinated sulfamic acid and salts thereof, brominated sulfamic acid and salts thereof. Examples include chloramine compounds such as salts, bromamine compounds, and hydrogen peroxide.

  Further, a low molecular weight polymer may be added in combination as a scale inhibitor.

  There is no restriction | limiting in particular as a low molecular weight polymer, All can be used suitably as what is used as a scale inhibitor of a cooling water system. For example, acrylic acid, methacrylic acid, HAPS (2-hydroxy-3-allyloxy-1-propanesulfonic acid), maleic acid, AMPS (2-acrylamido-2-methylpropanesulfonic acid), HEMA (2-hydroxyethylmeta) Acrylate), methyl acrylate, styrene sulfonic acid, isobutylene, one or two or more monomers polymerized or copolymerized, homopolymer or copolymer, preferably acrylic acid, methacrylic acid, HAPS, male A low molecular weight water-soluble polymer having an average molecular weight of 5,000 to 50,000, which is a homopolymer or copolymer obtained by polymerizing or copolymerizing one or more monomers selected from the group consisting of acid, AMPS, and isobutylene Is mentioned.

  These low molecular weight polymers may be used alone or in combination of two or more.

  The addition amount of the low molecular weight polymer is preferably 5 to 50 mg / L as the solid content concentration in the circulating water of the cooling water system.

<Corrosion inhibitor for copper-based materials>
The corrosion inhibitor for copper-based members of the present invention contains the above-mentioned compound (1) and an azole-based anticorrosive for copper, and these may be combined into a single component. It may be provided separately.

  There is no restriction | limiting in particular in the content rate of each component in the corrosion inhibitor of the copper-type member of this invention, Moreover, the corrosion inhibitor of the copper-type member of this invention is other than a compound (1) and an azole-type copper anticorrosive. May contain other chemicals such as anticorrosive, scale inhibitor, dispersant, slime control agent, release agent, antifoaming agent, surfactant, chelating agent, etc., but compound (1) and azole series In order to sufficiently obtain the excellent effect of the combined use with the copper anticorrosive, the corrosion inhibitor for the copper-based member of the present invention has a ratio of the azole-based copper anticorrosive to the compound (1) of 10 to 1000. It is preferable to contain these in an amount of about 50% by weight, particularly about 50 to 500% by weight.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Examples 1 to 3, Comparative Examples 1 to 5]
Evaluation based on "Rotation method" described in JIS K0100 "Industrial water corrosion test method" was performed. A support rod attached with one test piece was immersed in 1 L of test water in a beaker, and the support rod was rotated so that the linear flow velocity on the surface of the test piece was 0.5 m / sec. Evaluation was performed by measuring the corrosion rate of copper from the change in weight of the test piece before and after the test.

  Test water, chemicals used, test pieces, and test conditions are as follows.

<Test water>
In simulated cooling water, maleic acid isobutylene copolymer (maleic acid: isobutylene = 50: 50 (monomer molar ratio), molecular weight 20,000) as a solid content concentration of 5 mg / L, monochlororosulphate (mainly sodium salt) ) Was added so that the total residual chlorine measured value by the DPD method was 10 mg / L.
As the simulated cooling water, a predetermined amount of calcium chloride, magnesium sulfate, sodium bicarbonate, sodium silicate No. 3 was added to pure water, and the pH was adjusted to a predetermined value with sodium hydroxide or sulfuric acid.
Table 1 shows the water quality of the simulated cooling water used in the test.

<Drug>
Compound (1): A mixture containing a substance having a structure in which, in the general formula (1), X, Y and Z are selected from at least one of a hydrogen atom, a hydroxyethyl group, a carboxymethyl group or a salt thereof, A mixture mainly composed of a compound represented by the following general formula (2)

(A mixture mainly composed of a compound in which R is an alkyl group or alkenyl group having 6 to 18 carbon atoms and R is an alkyl group having 11 carbon atoms)
Azole copper anticorrosive: benzotriazole

<Specimen>
Copper (C1220) test piece with a long side of 50 mm, a short side of 30 mm, and a thickness of 1 mm (φ4 mm hole for screwing)

<Test conditions>
Test temperature: 40 ° C
Test period: 7 days (change all test water on the 3rd day of the test)

  The chemicals shown in Table 2 were added to the test water shown in Table 2 at the addition concentrations shown in Table 3 (however, no chemicals were added in Comparative Example 1), and the corrosion rate (mdd) of the copper test piece was determined. Are shown in Table 2.

<Discussion>
From Table 2, it is clear that the corrosion rate is greatly suppressed by using the compound (1) and the azole copper anticorrosive agent in combination with each other, and both components are used in combination. A synergistic effect was confirmed.

Claims (11)

A method for inhibiting corrosion of a copper-based member, comprising adding a compound represented by the following formula (1) and an azole-based anticorrosive agent for copper to an aqueous system in contact with the copper-based member.

(In the formula (1), R represents an alkyl group or an alkenyl group, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group, a benzyl group, a hydroxyalkyl group, or a carboxyalkyl group, and a hydroxyalkyl group. The carboxyalkyl group may form a salt.)   The method for inhibiting corrosion of a copper-based member according to claim 1, wherein the alkyl group or alkenylkill group of R in the formula (1) has 6 to 18 carbon atoms.   X, Y and Z in the formula (1) are selected from a hydrogen atom, a hydroxyethyl group, a carboxymethyl group, a hydroxyethyl group forming a salt, and a carboxymethyl group forming a salt. Item 3. The method for inhibiting corrosion of a copper-based member according to item 1 or 2.   The R in the formula (1) is an alkyl group having 11 carbon atoms, X is a hydrogen atom, Y is a hydroxyethyl group, and Z is a carboxymethyl group or a carboxymethyl group forming a salt. A method for inhibiting corrosion of copper-based members.   The method for inhibiting corrosion of a copper-based member according to any one of claims 1 to 4, wherein the azole-based anticorrosive for copper is benzotriazole.   The method for inhibiting corrosion of a copper-based member according to any one of claims 1 to 5, wherein the aqueous system is an aqueous system to which an oxidizing slime control agent is added. A corrosion inhibitor for inhibiting corrosion of a copper-based member in contact with an aqueous system, comprising a compound represented by the following (1) and an azole-based anticorrosive for copper: .

(In the formula (1), R represents an alkyl group or an alkenyl group, and X, Y, and Z each independently represent a hydrogen atom, an alkyl group, a benzyl group, a hydroxyalkyl group, or a carboxyalkyl group, and a hydroxyalkyl group. The carboxyalkyl group may form a salt.)   The corrosion inhibitor for copper-based members according to claim 7, wherein the alkyl group or alkenylkill group of R in the formula (2) has 6 to 18 carbon atoms.   X, Y and Z in the formula (1) are selected from a hydrogen atom, a hydroxyethyl group, a carboxymethyl group, a hydroxyethyl group forming a salt, and a carboxymethyl group forming a salt. Item 9. The corrosion inhibitor for copper-based members according to Item 7 or 8.   The R in the formula (1) is an alkyl group having 11 carbon atoms, X is a hydrogen atom, Y is a hydroxyethyl group, and Z is a carboxymethyl group or a carboxymethyl group forming a salt. A corrosion inhibitor for copper-based parts.   The corrosion inhibitor for copper-based members according to any one of claims 7 to 10, wherein the azole-based anticorrosive for copper is benzotriazole.