WO2008041569A1

WO2008041569A1 - Corrosion inhibitor and method of inhibiting corrosion

Info

Publication number: WO2008041569A1
Application number: PCT/JP2007/068619
Authority: WO
Inventors: Kazuyoshi Uchida; Yukimasa Shimura; Koichi Sato; Masuo Goto
Original assignee: Kurita Water Industries Ltd.; Nikko Chemical Institute Inc.
Priority date: 2006-10-03
Filing date: 2007-09-26
Publication date: 2008-04-10
Also published as: JP5092334B2; TWI412626B; TW200839033A; JP2008088516A; CN101528982A; CN101528982B

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) C10-22 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

Specification

Corrosion inhibitor and corrosion inhibition method

Field of Invention

[0001] The present invention relates to a corrosion inhibitor for suppressing the corrosion of metals used in heat exchangers and piping of boiler steam condensate systems, and particularly has excellent long-term storage stability in a high-temperature environment. It relates to a food inhibitor. The present invention also relates to a method for inhibiting corrosion using this corrosion inhibitor.

[0002] In a steam generating system such as a boiler, the metal constituting the heat exchanger and piping of the steam condensate system corrodes due to a decrease in pH caused by dissolved oxygen, bicarbonate ions, and carbon dioxide in the feed water. . In order to suppress this corrosion, in particular, a method using a chemical is widely practiced.

[0003] This agent is mainly a film-forming agent that forms an anticorrosive film on a metal surface so that steam condensate containing corrosive factors such as oxygen and carbon dioxide does not directly contact the metal surface. It is roughly divided into neutralizing agents that neutralize carbon dioxide contained in water. In order to suppress corrosion more effectively, one having both a film forming function and a neutralizing function has been proposed (see Japanese Patent Publication No. 4-45590). This includes 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 this drug, long-chain aliphatic amines have a film-forming function, alkanolamine compounds have a neutralizing function, and aliphatic alkali metal salts have a surfactant activity that emulsifies and disperses long-chain aliphatic amines in aqueous systems. It plays the role of each agent.

[0004] The aqueous emulsion drug having both the film forming function and the neutralizing function described above has insufficient storage stability and is not particularly suitable for long-term storage in a high-temperature environment. For this reason, in order to improve stability, some improvement proposals have been made by changing the type of surfactant and the type of amine that is a neutralizing agent (for example, JP-A-11-335878 and JP-A-2002). — 25 See publication 6462). These drugs contain a long chain aliphatic amine compound having 10 to 24 carbon atoms, an aliphatic amino alcohol compound, and a polyoxyethylene sorbitan fatty acid ester. Or a combination containing a long chain aliphatic amine compound having 10 to 24 carbon atoms, an aliphatic amino alcohol compound, and a polydaricerin ester compound. These agents basically serve as corrosion inhibitors for long-chain aliphatic amine compounds, aliphatic amino alcohol compounds, and surfactants.

Patent Document 1: Japanese Patent Publication No. 4-45590

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

Patent Document 3: Japanese Patent Laid-Open No. 2002-256462

[0005] With respect to an aqueous emulsion corrosion inhibitor having both a film forming function and a neutralizing function, an improvement proposal has been made for the purpose of improving storage stability. As shown in Examples of JP-A-11 335878 and JP-A-2002-256462, a method for producing these improved drugs is firstly a compound of a long-chain aliphatic amine compound and an aliphatic amino alcohol compound. And a polyglycerin ester compound, or a mixed solution of a long-chain aliphatic amine compound, an aliphatic amino alcohol compound, and a polyoxyethylene sorbitan fatty acid ester, which is dropped into cold water to form an aqueous emulsion. This is a two-stage batch process. In such a two-stage manufacturing method, it is necessary to have multiple equipment such as reaction kettles, and the amount of washing waste liquid discharged after production is large, and this washing waste liquid contains COD such as fatty acids. The burden on the environment is also a problem.

[0006] Even with these improved aqueous emulsions, the long-term storage stability is still not sufficient, especially in high-temperature environments. A pump is required.

Summary of the Invention

[0007] The present invention is a corrosion inhibitor having both a film forming function and a neutralizing function, and can be stably stored for a long time even in a high temperature environment, and can be easily produced in one batch. The object is to provide a possible corrosion inhibitor.

[0008] The corrosion inhibitor of the present invention contains components of the following groups (A) to (C).

(A) Long chain aliphatic amine having 10 to 22 carbon atoms

(B) Surfactant containing polyethylene glycol fatty acid ester

(C) 2-amino-2-methyl monopropanol, morpholine, and monoisopropanol amino One or more water-soluble amines selected from the group consisting of

[0009] This corrosion inhibitor comprises (A) a long-chain aliphatic amine, (B) a surfactant and (C) a water-soluble amine that is emulsified in an aqueous medium. Content is 0.3-2

It may be 0% by weight, (B) the surfactant content may be 2 to 4.5% by weight, and (C) the water-soluble amine content may be 0.5 to 50% by weight.

[0010] (B) The surfactant may include a polyethylene glycol fatty acid ester and a propylene glycol fatty acid ester and / or a glycerin fatty acid ester.

[0011] The content ratio of the polyethylene glycol fatty acid ester of component (B) and the propylene glycol fatty acid ester and / or glycerin fatty acid ester, in terms of weight ratio, polyethylene glycol fatty acid ester: propylene glycol fatty acid ester and / or glycerin fatty acid ester = 2:;! ~ 100: 1 may be sufficient.

[0012] The corrosion inhibitor of the present invention has both a film forming function and a neutralizing function. This corrosion inhibitor can be stored stably for a long period of time without property changes such as gelation (thickening) even in a high temperature environment. This corrosion inhibitor is a long-chain aliphatic amine, a surfactant, and a water-soluble amine placed in a production kettle and heated to stir to make a homogeneous solution. Water is then added to emulsify and gradually stirred. By cooling, it can be easily produced in one batch. With this manufacturing method, only one manufacturing pot is sufficient, and the amount of waste liquid discharged is greatly reduced.

Detailed description

[0013] The corrosion inhibitor of the present invention contains components of the following groups (A) to (C).

(A) Long chain aliphatic amine having 10 to 22 carbon atoms (hereinafter sometimes referred to as “component (A)”)

(B) Surfactant containing polyethylene glycol fatty acid ester (hereinafter sometimes referred to as “component (B)”)

(C) One or more water-soluble amines selected from the group consisting of 2-amino-2-methylmonopropanol, morpholine, and monoisopropanolamine (hereinafter sometimes referred to as “component (C)”. )

[0014] The long chain aliphatic amine having 10 to 22 carbon atoms of the component (A) is a component for forming a film for suppressing corrosion by water on the metal surface. The long chain aliphatic group has 10 to 22 carbon atoms, preferably 12 to 20 carbon atoms. If this carbon number is less than 10, In contrast, there is a possibility that a film will be formed, and the corrosion inhibiting function may be insufficient. On the other hand, when the number of carbon atoms exceeds 22, the corrosion inhibitor emulsions become gelled and the stability may be impaired.

[0015] The long chain aliphatic group constituting the long chain aliphatic amine may contain an unsaturated bond! /. In addition, in the amino group constituting the long-chain aliphatic amine, the hydrogen portion may be appropriately substituted with a hydrocarbon group such as a methyl group or an ethyl group. Further, the long chain aliphatic amine may be a fatty acid salt. In this case, examples of the fatty acid constituting the fatty acid salt include oleic acid, lauric acid, and stearic acid.

Among the long-chain aliphatic amines of component (A), preferred are, for example, dodecylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, octadecinoreamine, nonadecinoreamine , Saturated aliphatic amines such as eicosinoreamine, docosinoreamine, oleylamine, ricinoleinamine, linoleinoleamine, unsaturated aliphatic amines such as linoleylamine, mixed oils such as coconut oil amine and hardened beef tallow amine This force S is possible. Two or more types of long chain aliphatic amines may be used in combination.

[0017] Of the specific examples of these long-chain aliphatic amines, a particularly preferred one is octadecylamine. Octadecylamine is approved as an additive for boiler water in the U.S. FDA standards.When it is used as component (A), steam generated from the boiler leaks and comes into contact with food. However, there is no problem in terms of safety, so it has the advantage that it can be used in the food manufacturing industry.

[0018] The surfactant of component (B) contains a polyethylene glycol fatty acid ester, and preferably comprises 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, it is possible to use only polyethylene glycol fatty acid ester, but in order to realize a corrosion inhibitor with excellent storage stability, polyethylene glycol fatty acid ester and propylene glycol fatty acid ester and / or glycerin are used. It is preferable to use in combination with a fatty acid ester. These polyethylene glycol fatty acid esters are substances described in US FDA standards, and propylene glycol fatty acid esters and glycerin fatty acid esters are recognized as food additives and are suitable in terms of safety. [0019] The fatty acid of the polyethylene glycol fatty acid ester is preferably a fatty acid having 8 to 24 carbon atoms, particularly 10 to 22 carbon atoms. Specifically, oleic acid, lauric acid, stearic acid, coconut oil fatty acid, tall oil fatty acid, etc. Is mentioned.

[0020] Suitable polyethylene glycol (PEG) includes PEG400 (average molecular weight is 400), PEG600 (average molecular weight is 600), PEG3000 (average molecular weight is 3000), and the like.

[0021] The polyethylene glycol fatty acid ester has an HLB of 6-18, preferably 8-14, specifically PEG400 dioleic acid ester, PEG400 coconut oil fatty acid ester ester, PEG600 tonole oil lunar lunar acid ester ester, Examples include PEG400 monolaurate ester, PEG600 monolaurate, PEG400 monooleate, PEG600 monooleate, PEG400 monostearate, PEG600 stearate, PE G3000 monostearate. These polyethylene glycol fatty acid esters may be used alone or in combination of two or more.

[0022] As propylene glycol fatty acid ester, HLB is !!-9, preferably 2-6, and the same fatty acid as exemplified as the fatty acid of polyethylene glycol fatty acid ester. Examples include esters. Examples of the glycerin fatty acid ester include esters of glycerin having an HLB of 1 to 9, preferably 2 to 8, and fatty acids similar to those exemplified as the fatty acid of the polyethylene glycol fatty acid ester. Propylene glycol fatty acid ester and glycerin fatty acid ester may be used alone or in combination of two or more. In addition, one or more of propylene dallicol fatty acid ester and one or more of glycerin fatty acid ester may be used in combination.

[0023] The water-soluble amine of component (C) is a component for neutralizing carbon dioxide contained in water. As the water-soluble amine, 2-amino-2-methyl-propanol, morpholine, and monoisopropanolamine, which are US FDA standard products, are preferable, but not limited thereto.

Yes

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

[0024] The corrosion inhibitor of the present invention comprises the components (A), (B) and (C) in an aqueous medium such as water. It is provided as an emulsified composition. The content of the long-chain aliphatic amine as component (A) in such a corrosion inhibitor is 0.3 to 2.0% by weight, particularly 0.5 to 1.0% by weight. It is preferable. If the long-chain aliphatic amine content of component (A) is less than 0.3% by weight, it may be difficult to form a required film for preventing corrosion on metals. The amount of corrosion inhibitor used to form a film is excessive and uneconomical, and the stability of the corrosion inhibitor itself, particularly the emulsion stability, may be impaired. On the other hand, if it exceeds 2.0% by weight, the corrosion inhibitor tends to gel, making it difficult to form the required film on the metal member, and possibly closing a narrow metal pipe. is there. In addition, the corrosion inhibitor is likely to be phase-separated and the emulsion stability may be reduced.

[0025] The content of the component (B) surfactant in the corrosion inhibitor is 2 to 4.5% by weight, particularly 2.5 to

4. It is preferably 0% by weight. If the content of the component (B) surfactant is less than 2% by weight, the storage stability of the corrosion inhibitor is insufficient, and if it is more than 4.5% by weight, an improvement in the effect can be obtained. However, the amount of the surfactant used is increased, which is uneconomical.

[0026] As the component (B), it is preferable to use a polyethylene glycol fatty acid ester in combination with a propylene glycol fatty acid ester and / or a glycerin fatty acid ester. Polyethylene glycol fatty acid ester and propylene glycol fatty acid ester and / or glycerin fatty acid ester are used in a weight ratio of polyethylene glycol fatty acid ester: propylene glycol fatty acid ester and / or glycerin fatty acid ester = 2:;!-100 : 1, especially 4:;! ~ 60: 1 is preferred! /. Even if there are more polyethylene glycol fatty acid esters and less propylene glycol fatty acid esters and / or glycerol fatty acid esters than this range, conversely, even if there are fewer polyethylene glycol fatty acid esters and more propylene glycol fatty acid esters and / or glycerin fatty acid esters, these The effect of improving the storage stability of the present invention due to the combined use cannot be sufficiently obtained.

[0027] The content of the water-soluble amine of the component (C) in the corrosion inhibitor is 0.5 to 50% by weight, particularly 20 to

40% by weight is preferred! If the content of the water-soluble amine of component (C) is less than the above range, carbon dioxide gas may be neutralized. May be reduced.

[0028] The corrosion inhibitor of the present invention comprises (A) a long-chain aliphatic amine, (B) a surfactant, and (C) a water-soluble amine in a production kettle. Heat and stir to about 70 ° C to make a uniform solution, and then add a predetermined amount of water to this while keeping the production kettle at 40-60 ° C; stir for about ~ 8 hours, then By gradually cooling to room temperature while stirring, it can be easily prepared in one production kettle.

[0029] The corrosion inhibitor of the present invention may optionally contain, in addition to the above-described components (A) to (C), conventional components of corrosion inhibitors and other auxiliary additive components as necessary. Examples of such optional additives include solubilizers such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and glycerin, sequestering agents, and antifreeze agents.

[0030] The corrosion inhibitor of the present invention is continuously or intermittently added to the feed water or steam so as to have a concentration of 0.;! To 200 mg / L, preferably 1 to 100 mg / L. Corrosion of metal parts can effectively suppress corrosion of metal parts.

Example

[0031] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[0032] Examples;! To 5, Comparative Examples 1 and 2

[Preparation of corrosion inhibitors]

Components (A) to (C) or other components having the composition shown in Table 1 were charged into a production kettle and heated to 60 to 70 ° C with stirring to dissolve uniformly. Next, water was added in the amount shown in Table 1, and the production kettle was kept at 45-50 ° C and stirred for 3-4 hours. Then, gradually cooled to room temperature with stirring

Yes

[0033] [Table 1] Mixing ratio (parts by weight)

* Polyoxyethylene (20) sorbitan monooleate

[0034] [Evaluation of storage stability]

The drugs prepared in each example were stored in a constant temperature bath at 25 ° C or 45 ° C, taken out in a timely manner, examined for changes in viscosity over time, and the results are shown in Table 2.

[0035] [Table 2]

[0036] According to Table 2, the corrosion inhibitor of the present invention is stable when stored at 45 ° C, and the viscosity hardly changes and is excellent in stability. However, the corrosion inhibitor of the comparative example has a temperature of 45 ° C. It is clear that thickening and storage properties change upon storage.

[0037] [Evaluation of corrosion inhibition effect] For the corrosion inhibitors prepared in each example, the corrosion inhibition effect of the steam condensate system using a test boiler was evaluated as shown below, and the results are shown in Table 3.

Soft water was supplied to a steam generator with pressure IMPa, and the test piece made of mild steel was immersed in steam condensed water, and the corrosion rate after 48 hours was examined. A steam generator was also added with an oxygen scavenger to adjust the dissolved oxygen concentration to 1 mg / L or less. The temperature of the steam condensate was kept at about 40 ° C. Softened water was obtained by treating tap water from Nogi Town in Tochigi Prefecture, Japan, and the average acid consumption (pH 4.8) was 40 mg-CaCO / L. Each corrosion inhibitor

Three

The amount of the preparation added was 100 mg / L—water supply (the amount of amine added was 30 mg / L water-soluble amine and 0.7 mg / U octadecinoleamine).

Note that no corrosion inhibitor is added! /, And the corrosion rate in the case is shown in Table 3 as a blank.

[Table 3] Corrosion inhibition effect evaluation results

From Table 3, it can be seen that the corrosion inhibitor of the present invention has the same effect as that of the conventional product and exhibits an excellent effect.

Claims

The scope of the claims

[1] A corrosion inhibitor comprising the following groups (A) to (C):

(A) Long chain aliphatic amine having 10 to 22 carbon atoms

(B) Surfactant containing polyethylene glycol fatty acid ester

(C) at least one water-soluble amine selected from the group consisting of 2-amino-2-methylmonopropanol, morpholine, and monoisopropanolamine

[2] The corrosion inhibitor according to claim 1, wherein (A) a long-chain aliphatic amine, (B) a surfactant, and (C) a water-soluble amine are emulsified in an aqueous medium, The content of the chain aliphatic amine is 0.3 to 2.0% by weight, the content of the (B) surfactant is 2 to 4.5% by weight, and (C) the content of the water-soluble amine is 0. A corrosion inhibitor characterized by being 5 to 50% by weight.

[3] The corrosion inhibitor according to claim 1, comprising (B) a surfactant power, a polyethylene glycol fatty acid ester, a propylene glycol fatty acid ester and / or a dariserine fatty acid ester.

[4] In Claim 3, the content ratio of the polyethylene glycol fatty acid ester of component (B) and the propylene glycol fatty acid ester and / or dalyserin fatty acid ester is polyethylene glycol fatty acid ester: propylene glycol fatty acid ester and / or by weight ratio. Corrosion inhibitor characterized by glycerin fatty acid ester = 2:;! ~ 100: 1.

[5] The corrosion inhibitor as set forth in claim 1, wherein (A) the long-chain aliphatic amine has 12 to 20 carbon atoms.

[6] Claim 1! /, (A) long chain aliphatic amine is dodecylamine, tridecylamine, tetradecylamine, heptadecylamine, hexadecylamine, octadecylamine, nonadecinoreamine, eicosylamine, docosylamin A corrosion inhibitor that is at least one of oleylamine, ricinoleinamine, linoleylamine, linoleylamine, coconut oil amine, and hardened tallowamine.

[7] The corrosion inhibitor according to claim 1, wherein (A) the long-chain aliphatic amine is octadecylamine.

Yes

[8] In Claim 1, (B) the surfactant is a polyethylene glycol fatty acid ester and a polymer. A corrosion inhibitor comprising pyrendalicol fatty acid ester and / or dalyserin fatty acid ester.

[9] In Claim 1, the polyethylene glycol fatty acid ester is PEG400 dioleate, PEG400 coconut oil fatty acid ester, PEG600 tall oil fatty acid ester, PEG400 monolaurate, PEG600 monolaurate, PEG400 monooleate, PEG600 monooleate A corrosion inhibitor that is at least one of an ester, PEG400 monostearate ester, PEG600 stearate ester, and PEG3000 monostearate ester.

[10] The corrosion inhibitor according to claim 3, wherein the propylene glycol fatty acid ester is propylene glycol monooleate.

[11] The corrosion inhibitor according to claim 3, wherein the glycerin fatty acid ester is glycerin monooleate.

[12] A method for inhibiting corrosion, wherein the corrosion inhibitor according to claim 1 is added to water in a steam condensate system of a boiler, and corrosion of a metal in contact with the water is inhibited.