TWI412626B - A method for suppressing corrosion and inhibiting corrosion - Google Patents

Abstract

A corrosion inhibitor which combines a film-forming function with a neutralizing function, can be stably stored for long even in a high-temperature environment, and can be easily produced in one batch. The corrosion inhibitor comprises ingredients respectively in the following groups (A) to (C): (A) C<SUB>10-22</SUB> aliphatic amines; (B) surfactants comprising a polyethylene glycol/fatty acid ester; and (C) one or more water-soluble amines selected from the group consisting of 2-amino-2-methylpropanol, morpholine, and monoisopropanolamine.

Description

Method for inhibiting corrosion and method for inhibiting corrosion

The present invention relates to a corrosion inhibiting agent for suppressing corrosion of a metal used in a heat exchanger, a pipe, or the like of a boiler vapor condensate system, and particularly for a corrosion inhibiting agent having high long-term storage stability in a high temperature environment. Further, the present invention relates to a method for suppressing corrosion by using the corrosion inhibiting agent.

The steam system generated by a boiler or the like is caused by a decrease in pH due to dissolved oxygen, bicarbonate ions or carbon dioxide in the feed water, and causes corrosion of the metal such as a heat exchanger or a pipe constituting the water vapor and the condensed water system. In order to suppress this corrosion, a method of using a pharmaceutical agent is particularly widely used.

The agent is roughly classified into a water-based vapor or a condensed water containing a corrosive factor such as oxygen or carbon dioxide, which is not directly in contact with a metal surface, and is roughly classified into a film-forming agent which forms an anti-corrosion film on a metal surface, and is neutralized and contained in water. A neutralizing agent for carbon dioxide. In order to suppress corrosion more effectively, it has been revealed that one of the functions of forming a film and a neutralizing function is prepared (Japanese Patent Publication No. 4-45590). This is a long-chain aliphatic amine having 10 to 24 carbon atoms, an alkanolamine compound, and an aliphatic alkali metal salt having 8 to 24 carbon atoms. In the agent, a long-chain aliphatic amine functions as a film forming function, an alkanolamine compound functions as a neutralizing function, and an aliphatic alkali metal salt functions as a surfactant for dispersing a long-chain aliphatic amine in water. Character.

The aqueous emulsifier having both the function of forming the film and the neutralization function has insufficient storage stability, and is particularly unsuitable for long-term protection in a high temperature environment. Save. Therefore, in order to improve the stability, several types of alternative surfactants and types of amines of the neutralizing agent have been disclosed (for example, JP-A-H11-335878, JP-A-2002-256462). These agents include a combination of a long-chain aliphatic amine compound having 10 to 24 carbon atoms and an aliphatic amine alcohol compound and a polyethylene oxide sorbitan fatty acid ester, or a long-chain fat having 10 to 24 carbon atoms. A combination of a amine compound, an aliphatic amine alcohol compound, and a polyglyceryl ester compound. These agents are basically a corrosion inhibiting agent which is a combination of a long-chain aliphatic amine compound and an aliphatic amine alcohol compound and a surfactant.

Patent Document 1: Special Fair No. 4-45590

Patent Document 2: Japanese Laid-Open Patent Publication No. Hei 11-335878

Patent Document 3: JP-A-2002-256462

The aqueous emulsification-based corrosion-inhibiting agent having both the film forming function and the neutralization function is improved to improve storage stability. In the method of producing such an improved pharmaceutical agent, a method of producing a modified aliphatic acid compound, an aliphatic amine compound, and a polyglycerol compound, or After preparing a mixture of a long-chain aliphatic amine compound, an aliphatic amine alcohol compound, and a polyethylene oxide sorbitan fatty acid ester, the mixture is dropped into cold water to carry out a two-stage batch process of aqueous emulsification. In the two-stage process, it is necessary to maintain a plurality of reactors and the like, and the amount of the washing waste liquid after the manufacture is also large, and the washing waste liquid is a COD containing a fatty acid, and the load is also caused by the environment. .

At the same time, even if these are improved aqueous emulsification agents, they are still The storage stability is still insufficient, especially in the high temperature environment, it is easy to gel (grow), and the actual use must be a high viscosity pump.

An object of the present invention is to provide a corrosion inhibiting agent which can be stably stored in one batch and which can be stably stored in a high temperature environment while having a function of forming a film and a neutralizing function.

The agent for suppressing corrosion of the present invention is a component containing the following groups (A) to (C).

(A) a long-chain aliphatic amine having 10 to 22 carbon atoms, (B) a surfactant containing a polyethylene glycol fatty acid ester, and (C) one or more selected from the group consisting of 2-amino-2 a water-soluble amine in the group of methyl-propanol, morpholine, and monoisopropanolamine.

The corrosion inhibiting agent is prepared by emulsifying (A) a long-chain aliphatic amine, (B) a surfactant, and (C) a water-soluble amine in an aqueous medium. (A) The content of the long-chain aliphatic amine is 0.3. ~2.0% by weight, (B) the content of the surfactant is 2 to 4.5% by weight, and the content of the (C) water-soluble amine is 0.5 to 50% by weight.

(B) The surfactant may also contain a polyethylene glycol fatty acid ester and a propylene glycol fatty acid ester and/or a glycerin fatty acid ester.

The content ratio of the polyethylene glycol fatty acid ester of the component (B) to the propylene glycol fatty acid ester and/or the glycerin fatty acid ester may also be a polyethylene glycol fatty acid ester: propylene glycol fatty acid ester and/or glycerin. Fatty acid ester = 2:1~100:1.

The agent for suppressing corrosion of the present invention has both a function of forming a film and a function of neutralizing. The corrosion-inhibiting agent does not change in properties such as gelation (growth) even in a high-temperature environment, and can be stably stored for a long period of time. The agent for inhibiting corrosion is prepared by placing a long-chain aliphatic amine, a surfactant, and a water-soluble amine in a production pot, heating and stirring, and then forming a uniform solution, wherein water is introduced, emulsified, and stirred while slowly cooling. One batch can be easily manufactured. In the production method, one pot can be produced, and the amount of waste liquid discharged is also greatly reduced.

The agent for suppressing corrosion of the present invention is a component of each group containing the following (A) to (C).

(A) A long-chain aliphatic amine having 10 to 22 carbon atoms (hereinafter referred to as "(A) component").

(B) A surfactant containing a polyethylene glycol fatty acid ester (hereinafter referred to as "(B) component").

(C) one or more water-soluble amines selected from the group consisting of 2-amino-2-methyl-propanol, morpholine, and monoisopropanolamine (hereinafter referred to as "(C) component") .

(A) The long-chain aliphatic amine having 10 to 22 carbon atoms of the component is a component of the metal surface to suppress the formation of a film by corrosion of water. The long-chain aliphatic group has 10 to 22 carbon atoms, preferably 12 to 20 carbon atoms. When the number of carbon atoms is less than 10, it may be difficult to form a film for the metal, and the corrosion prevention function will be insufficient. On the other hand, when the number of carbon atoms exceeds 22, the emulsification of the corrosion-inhibiting agent is likely to cause gelation and damage stability.

The long-chain aliphatic group constituting the long-chain aliphatic amine may also contain unsaturated key. Further, the hydrogen moiety of the amine group constituting the long-chain aliphatic amine may be appropriately substituted by a hydrocarbon group such as a methyl group or an ethyl group. The long chain aliphatic amine is more preferably a fatty acid salt. In this case, as the fatty acid constituting the fatty acid salt, examples of oleic acid, lauric acid, and stearic acid may be mentioned.

Among the long-chain aliphatic amines of the component (A), for example, laurylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, stearylamine, pentadecylamine, icosylamine, twenty-two Examples of amines, oleylamine, ricinoleamine, linoleylamine, linolenic amine, coconut oleylamine, and hardened tallow amines and the like. Further, two or more kinds of long-chain aliphatic amines may be used in combination.

Among the specific examples of such long-chain aliphatic amines, octadecylamine is particularly preferred. Octadecylamine is used in the US FDA standard and is considered to be used as a boiler water additive. When used as the component (A), even if the vapor generated by the boiler leaks out and comes into contact with food, there is no safety problem. Therefore, it is beneficial for use in food manufacturing.

The surfactant of the component (B) is a polyethylene glycol fatty acid ester, preferably a combination of a polyethylene glycol fatty acid ester and a propylene glycol fatty acid ester and/or a glycerin fatty acid ester. As the surfactant, a polyethylene glycol fatty acid ester can also be used, and in order to achieve a corrosion-suppressing agent with good storage stability, a combination of a polyethylene glycol fatty acid ester and a propylene glycol fatty acid ester and/or glycerin fat can be used. An acid ester is preferred. These polyethylene glycol fatty acid esters are substances described in the US FDA standard, and propylene glycol fatty acid esters and glycerin fatty acid esters are recognized as food additives, and the safety surface is good.

As the fatty acid of the polyethylene glycol fatty acid ester, it is preferably a carbon number of 8 to 24, particularly a fatty acid of 10 to 22, for example, oleic acid, lauric acid, Examples of stearic acid, coconut oil fatty acid, tall oil fatty acid and the like.

Desirable polyethylene glycol (PEG) is exemplified by PEG 400 (average molecular weight of 400), PEG600 (average molecular weight of 600), and PEG 3000 (average molecular weight of 3,000).

The polyethylene glycol fatty acid ester such as HLB is 6-18, preferably 8-14, specifically, for example: PEG400 dioleate, PEG400 coconut fatty acid ester, PEG600 tall oil fatty acid ester, PEG400 monolaurate PEG600 monolaurate, PEG400 monooleate, PEG600 monooleate, PEG400 monostearate, PEG600 stearate, PEG3000 monostearate, and the like. These polyethylene glycol fatty acid esters may be used alone or in combination of two or more.

The propylene glycol fatty acid ester has, for example, an ester example of a fatty acid having an HLB of from 1 to 9, more preferably from 2 to 6, which is the same as the fatty acid of a propylene glycol and a polyethylene glycol fatty acid ester. Further, as the glycerin fatty acid ester, the HLB is 1 to 9, more preferably 2 to 8, and is the same as the fatty acid ester exemplified by the fatty acid of glycerin and polyethylene glycol fatty acid ester. The propylene glycol fatty acid ester and the glycerin fatty acid ester may be used alone or in combination of two or more. In addition, one type or two or more types of propylene glycol fatty acid esters may be used in combination with one or more types of glycerin fatty acid esters.

The water-soluble amine of the component (C) is a component for neutralizing carbon dioxide contained in water. As a water-soluble amine, such as: 2-amino-2-methyl-propanol, morpholine, monoisopropanolamine, which is contained in the US FDA specification, is not limited thereto.

These water-soluble amines may be used alone or in combination of two or more. Use it.

The agent for suppressing corrosion of the present invention is an emulsified composition of the component (A), the component (B) and the component (C) in an aqueous medium such as water. The content of the long-chain aliphatic amine of the component (A) in the corrosion inhibiting agent is preferably 0.3 to 2.0% by weight, particularly preferably 0.5 to 1.0% by weight. When the content of the long-chain aliphatic amine of the component (A) is less than 0.3% by weight, the film required for corrosion resistance may not be formed for the metal, and in order to form the film, the agent for suppressing corrosion is excessively used, resulting in economy. Poor surface, at the same time, the fear and the stability of the anti-corrosion agent, especially the emulsion stability. On the other hand, when it exceeds 2.0% by weight, the corrosion inhibiting agent is easily gelled, and it is difficult for the metal member to form a desired film, and the narrow metal pipe may be blocked. Further, the corrosion inhibiting agent is easily phase-separated to lower the emulsion stability.

The surfactant content of the component (B) in the corrosion inhibiting agent is preferably from 2 to 4.5% by weight, particularly preferably from 2.5 to 4.0% by weight. When the surfactant content of the component (B) is less than 2% by weight, the storage stability of the corrosion inhibiting agent will be insufficient, and if it is more than 4.5% by weight, the effect is not higher, but the amount of the surfactant is increased. Lead to poor economic conditions.

The component (B) is preferably a polyethylene glycol fatty acid ester and a propylene glycol fatty acid ester and/or a glycerin fatty acid ester. The ratio of use of the polyethylene glycol fatty acid ester to the propylene glycol fatty acid ester, and/or the glycerin fatty acid ester is a weight ratio of polyethylene glycol fatty acid ester: propylene glycol fatty acid ester, and/or glycerin fatty acid ester = 2:1~100:1, especially 4:1~60:1 is the best. If the polyethylene glycol fatty acid ester is outside the range, the propylene glycol fatty acid ester and/or glycerin fatty acid ester is less than the range, and conversely, the polyethylene glycol fatty acid ester is less than the range. When the propylene glycol fatty acid ester and/or the glycerin fatty acid ester are outside the range, the effect of improving the storage stability of the present invention cannot be obtained by the combination of the above.

The content of the component (C) of the water-soluble amine corrosion inhibitor is 0.5 to 50% by weight, particularly preferably 20 to 40% by weight. When the water-soluble amine content of the component (C) is less than the range, it is difficult to neutralize the carbonic acid gas, and if it is too much, the emulsion stability of the corrosion inhibiting agent is lowered.

The anti-corrosion agent of the present invention is characterized in that the long-chain aliphatic amine of the component (A) and the surfactant of the component (B) and the water-soluble amine of the component (C) are placed in a manufacturing pot and heated to 60 to 70 ° C. Stir to make a homogeneous solution, then put the quantified water here, keep the pot at 40~60 °C, stir for 1~8 hours, then slowly cool to room temperature after stirring, it can be easily 1 Modulation is carried out in a manufacturing pot.

In addition to the above-mentioned components (A) to (C), the anti-corrosion agent of the present invention may optionally contain a conventional component for suppressing the corrosive agent or other auxiliary additive component. Examples of the optional additive include, for example, a solubilizing agent such as ethylene glycol, propylene glycol, butylene glycol, hexanediol or glycerin, a metal ion blocking agent, and an antifreezing agent.

The agent for suppressing corrosion of the present invention can effectively inhibit metal by adding 0.1 to 200 mg/L, preferably 1 to 100 mg/L, as a concentration of amine in the case of supplying water or steam. Part of the corrosion.

[Examples]

The present invention will be more specifically described below by way of examples and comparative examples.

(Examples 1 to 5, Comparative Examples 1, 2) [Preparation of corrosion inhibitors]

In the mixture shown in Table 1, the components (A) to (C) or other ingredients are placed in a manufacturing pot, heated to 60-70 ° C, and uniformly dissolved by stirring. Next, the amount of water shown in Table 1 was charged, and the pot was kept at a temperature of 45 to 50 ° C and stirred for 3 to 4 hours. Subsequently, it was slowly cooled to room temperature while stirring.

[Assessment of storage stability]

Each of the agents prepared in each of the samples was allowed to stand in a thermostatic chamber at 25 ° C or 45 ° C for a standing time, and after taking out at an appropriate time, the change in viscosity was measured with time. The results are shown in Table 2.

As shown in Table 2, the corrosion-inhibiting agent of the present invention has a viscosity which hardly changes even when stored at 45 ° C, and has good stability, and the corrosion-inhibiting agent of the comparative example is stored at 45 ° C and then increased. Sticky, traits change significantly.

[Evaluation of the effect of suppressing corrosion] For the corrosion inhibiting agent prepared in each of the examples, the following evaluation of the corrosion inhibiting effect of the steam condensed water system using the test boiler was carried out, and the results are shown in Table 3.

Water was supplied to a steam generator at a pressure of 1 MPa. After continuous operation, a test ball made of mild steel was immersed in steam condensed water to measure the corrosion rate after 48 hours. The deoxidizer is added to the steam generator to prepare a dissolved oxygen concentration of 1 mg/L or less. The temperature of the vapor condensed water was maintained at about 40 °C. The soft water is treated with tap water of Noki-cho, Tochigi Prefecture, Japan, and the average oxygen consumption (pH 4.8) is 40 mg-CaCO ₃ /L. The amount of each of the corrosion inhibitors was 100 mg/L of water (the amount of the amine added was 30 mg/L of water-soluble amine and 0.7 mg/L of stearylamine).

In addition, the corrosion rate at the time when the agent for suppressing corrosion was not added was a blank test, as shown in Table 3.

It is proved from Table 3 that the corrosion inhibiting agent of the present invention has the same effect of suppressing corrosion as the prior art and has a good effect.

Claims (10)

A corrosion inhibiting agent characterized by containing the following components (A) to (C); (A) a long-chain aliphatic amine having 10 to 22 carbon atoms; and (B) a polyethylene glycol fat a surfactant of a acrylate and a propylene glycol fatty acid ester and/or a glycerin fatty acid ester, (C) at least one selected from the group consisting of 2-amino-2-methyl-propanol, morpholine, and monoisopropanolamine A group of water soluble amines. The agent for inhibiting corrosion according to the first aspect of the invention, wherein the (A) long-chain aliphatic amine, (B) surfactant, and (C) water-soluble amine are emulsified in an aqueous medium, and (A) The long-chain aliphatic amine content is 0.3 to 2.0% by weight, (B) the surfactant content is 2 to 4.5% by weight, and (C) the water-soluble amine content is 0.5 to 50% by weight. The anti-corrosion agent according to claim 1, wherein the ratio of the polyethylene glycol fatty acid ester of the component (B) to the propylene glycol fatty acid ester and/or the glycerin fatty acid ester is polyethylene glycol by weight ratio. Fatty acid ester: propylene glycol fatty acid ester and / or glycerol fatty acid ester = 2:1 ~ 100:1. The anti-corrosion agent according to claim 1, wherein the (A) long-chain aliphatic amine has 12 to 20 carbon atoms. The anti-corrosion agent according to claim 1, wherein the (A) long-chain aliphatic amine is laurylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, octadecylamine, and hexadecylamine. At least one of amylamine, dodecaamine, oleylamine, ricinoleamine, linoleylamine, linolenic amine, coconut oil amine, and hardened tallow amine. The anti-corrosion agent according to claim 1, wherein the (A) long-chain aliphatic amine is octadecylamine. The anti-corrosion agent according to claim 1, wherein the polyethylene glycol fatty acid ester is PEG400 dioleate, PEG400 coconut oil fatty acid ester, PEG600 tall oil fatty acid ester, PEG400 monolaurate, PEG600 At least one of monolaurate, PEG400 monooleate, PEG600 monooleate, PEG400 monostearate, PEG600 stearate, and PEG3000 monostearate. The agent for inhibiting corrosion according to claim 1, wherein the propylene glycol fatty acid ester is propylene glycol monooleate. The agent for inhibiting corrosion according to claim 1, wherein the glycerin fatty acid ester is glycerol monooleate. A method for suppressing corrosion characterized in that the corrosion inhibiting agent according to claim 1 of the patent application is added to water of a steam condensate of a boiler to suppress corrosion of a metal in contact with the water.