JPS6154874B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for suppressing metal corrosion in steam generation systems and the like. In equipment that generates steam, such as boilers and concentrators, points that come into contact with steam and condensed water are often affected by a drop in pH due to the action of oxygen, carbon dioxide, or other acidic substances contained in the feed water. Corrode. Measures to prevent this corrosion include ion exchange treatment and deaeration treatment of the feed water, as well as treatment with chemicals, and long-chain aliphatic amines are mainly used as chemicals. By the way, long-chain aliphatic amines are water-insoluble;
Since it is difficult to directly and uniformly disperse this amine in water, one way to use it as a corrosion inhibitor is to convert the amine into a soluble salt such as acetate and make an aqueous solution, or Attempts have been made to add the amine directly as an alcoholic solution to the feed water. However, solution-type corrosion inhibitors have the disadvantage that when diluted with feed water, solutes coagulate and precipitate due to the influence of electrolytes present in the feed water, accumulating on vessel walls and pipe walls. There was a problem that concentration control was difficult. On the other hand, the method of using a long-chain aliphatic amine in the form of an emulsified dispersion is not affected by electrolytes and the like. However, when diluted with feed water, the emulsified dispersion state must be maintained stably, which is the same as with solution-type corrosion inhibitors. It is required that the emulsified dispersion state is stable even when stored for a long time. In addition, in recent years, boilers have become larger and processes have become more labor-saving, so water tanks with larger capacities than before are being used, and the residence time of boiler supply water in the water tank has also increased. Due to the trend toward significantly longer retention times, steam-based corrosion inhibitors have become required to be stable over time in water tanks. Furthermore, in fields such as the food industry, there is a strong demand for vapor-based corrosion inhibitors that are highly safe for the human body. In addition, steam generated from boilers is often released into the atmosphere due to various reasons such as pressure adjustment, and there is a possibility that the released steam may contain components of steam-based corrosion inhibitors. It is preferable that the components of the corrosion inhibitor have higher safety. The present inventors focused on the above points and completed the present invention as a result of repeated research to develop a vapor-based corrosion inhibitor that solved the above-mentioned problems by using an emulsifier that is highly safe for the human body. did. That is, the present invention provides (A) a long-chain aliphatic amine with 10 to 24 carbon atoms, (B) an ethylene oxide adduct (additional mole number of 10 to 50) of a long-chain fatty acid with 8 to 24 carbon atoms and a monoester of sorbitan; (C) A steam-based corrosion inhibitor composition comprising an aqueous emulsion containing a long-chain fatty acid having 8 to 24 carbon atoms and an ester of polyglycerin having a degree of polymerization of 2 to 15. The long-chain aliphatic amine used as component (A) in the present invention has 1 to 3, preferably 1, alkyl or alkenyl group having 10 to 24 carbon atoms, preferably 12 to 20 carbon atoms. An amine having a lower number of carbon atoms than this is inferior in metal corrosion prevention effect, and an amine having a higher number of carbon atoms than this may cause undesirable phenomena such as gelation. Specific examples of long chain aliphatic amines suitable for the present invention include dodecylamine,
Saturated aliphatic amines such as tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, docosylamine, oleylamine, ricinoleylamine, linoleylamine, linolenylamine, etc. unsaturated aliphatic amines, coconut oil amines, hydrogenated tallow amines, and mixtures thereof. By the way, when using octadecylamine, which is approved for use as an additive for boiler water according to US FDA standards, as component (A) of the present invention,
Since there is no safety problem even if the steam generated from the boiler leaks and comes into contact with food, it has the advantage that it can also be used in the food manufacturing industry. Component (A) is preferably used in a proportion of 0.5 to 20% by weight based on the total amount of the composition; if it is less than this, the stability of the composition will be poor, while if it is more than this, it will easily gel and dispersion will be poor. This is not desirable as it becomes difficult. Component (B) used in the present invention is an ethylene oxide adduct of a fatty acid having 8 to 24 carbon atoms, preferably 10 to 22 carbon atoms, and a monoester of sorbitan, and the number of moles added is in the range of 10 to 50, preferably 15 to 40. It is in. Examples of such compounds include monomers of sorbitan with fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, erucic acid, linoleic acid and linolenic acid. Examples include compounds obtained by adding ethylene oxide to esters, and these compounds are generally highly safe and are widely used in the fields of cosmetics and pharmaceuticals. In particular, polysorbate 60 or polysorbate 30, which are ethylene oxide adducts of sorbitan monoester of stearic acid or oleic acid, have been approved by the US FDA.
They are recognized as ``direct food additives that are permitted for human consumption'' in the standards, and when these compounds are used as component (B), there is no risk of boiler water coming into contact with food. Since there is no problem in terms of safety, it can also be used in the food manufacturing industry. Component (C) of the present invention has 8 to 24 carbon atoms, preferably 10 carbon atoms.
-22 long chain fatty acids and degree of polymerization 2-15, preferably 2
-10 polyglycerols, preferably having an average number of fatty acid residues per molecule of 2 or less. Specific examples of such compounds include fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, erucic acid, linoleic acid and linolenic acid, and fatty acids of the formula There are esters of polyglycerol represented by and mixtures thereof. Among these compounds, those that pass FAO/WHO standards are approved for use in food according to the Food Additives Official Standards, and fatty acids manufactured from food fats and oils such as corn oil and polyglycerin with a degree of polymerization of 10 or less Esters are recognized as ``direct food additives that are permitted to be added to foods for human consumption'' under US FDA standards. Therefore, if polyglycerin fatty acid esters approved by the Food Additives Official Standards or FDA standards are used as component (C), there is a risk that boiler water may come into contact with food. It has the advantage that it can also be used in the food manufacturing industry since there is no problem in terms of safety. In the composition of the present invention, the weight ratio of component (A) to the sum of components (B) and (C) is 1:1 to 1:1.
It is desirable that the content be within the range of 7. If it is outside this range, unfavorable situations such as insufficient dispersibility when diluted with water, poor long-term storage stability, and phase separation during storage may occur. invite. Furthermore, it is desirable that the weight ratio of component (B) and component (C) be in the range of 1:1 to 5:1; outside this range, dispersibility and storage stability will deteriorate when diluted with water. . The vapor-based corrosion inhibitor composition of the present invention uses component (A) as a corrosion inhibiting component and components (B) and (C) as emulsifiers, so it itself has excellent long-term storage stability, and when diluted with water. However, it shows good dispersion stability, and its stability does not deteriorate over time. In addition, since the composition of the present invention is highly safe, it can be used as a corrosion inhibitor in boilers and the like without any problem even in factories where safety restrictions are severe, such as food factories. Such an effect can only be brought about by using the (A) component emulsifier together with the (B) component and (C) component, and if only one of the (B) component or (C) component is used. In this case, the effects achieved by the present invention cannot be obtained. The corrosion inhibitor composition of the present invention essentially contains three components (A), (B), and (C), but may optionally contain conventional components for corrosion inhibitors and other auxiliary additive components as necessary. I can do it. Examples of such optional additives include solubilizers such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and glycerin, emulsion stabilizers such as acetic acid or its salts, sequestering agents, and antifreeze agents. Examples include. The corrosion inhibitor composition of the present invention can be added continuously or intermittently to water or steam to provide an amine content of 0.1 to 100 ppm, preferably 1 to 10 ppm. Inhibits corrosion. The corrosion inhibitor composition of the present invention has excellent dispersion stability even if the diluent when diluted with water is alkaline, so it can be used in combination with other basic water treatment agents without any disadvantage. . Next, the present invention will be explained in more detail with reference to Examples. The evaluation method of the composition in each example is as follows. 1 0.1% diluted solution dispersion stability and stability over time (1) Neutral solution Dilute 0.1 g of sample with 100 ml of 25°C tap water that has been softened with cation exchange resin, stir well to disperse, and store for 1 day. The dispersion state was determined with the naked eye after being allowed to stand still. Next, this diluted solution was allowed to stand for 6 days, and the dispersion state after 7 days was visually judged to evaluate the stability over time. The evaluation criteria are shown below. 〇……Evenly distributed. △...Some floating matter was observed on the liquid surface. ×... Aggregates are generated. (2) Alkaline solution (PH10) 0.1g of the sample was diluted with 100ml of 25℃ tap water that had been softened with a cation exchange resin, and after adjusting the pH to 10.0 by adding 10% aqueous sodium hydroxide solution while stirring, In the same manner as in (1), the state of dispersion was visually determined after 1 day and 7 days. 2. Long-term storage stability 80 g of the sample was placed in a 120 ml glass bottle and stored at room temperature for 30 days, and its appearance was visually evaluated according to the following criteria. 〇…No phase separation was observed, indicating a good emulsification state. x... Indicates phase separation or gelation. Example 1 10 parts by weight of octadecylamine, 20 parts by weight of emulsifier (if two types of emulsifiers are used, 10 parts by weight each), 20 parts by weight of propylene glycol, and pure water
A metal corrosion inhibitor sample was prepared by mixing and emulsifying 50 parts by weight. Table 1 shows the type of emulsifier used and the stability test results for each sample.

[Table] Example 2 5 parts by weight of dodecylamine, polyglyceryl stearate (average weight of polyglycerin 3.8, 1
Average number of fatty acid residues per molecule 1.5) 2.5 parts by weight, polyoxyethylene sorbitan fatty acid ester 2.5
parts by weight, 0.1 part by weight of acetic acid, and pure water were added to make the total amount 100 parts by weight, and the mixture was mixed and emulsified to prepare a sample. Table 2 shows the types of polyoxyethylene sorbitan fatty esters and the stability test results for each sample.

[Table] Shows the number of moles of tyrene oxide added.
Example 3 5 parts by weight of octadecylamine, 2.5 parts by weight of polyoxyethylene sorbitan monooleate (20 moles of ethylene oxide added), 2.5 parts by weight of polyglycerin fatty acid ester, 0.1 part by weight of acetic acid and pure water were added to bring the total amount to 100 parts by weight. A sample was prepared by mixing and emulsifying. Table 3 shows the types of polyglycerol fatty acid esters and the stability test results for each sample.

[Table] Note) Average degree of polymerization of polyglycerin
is 3.6~4.2
Example 4 5 parts by weight of octadecylamine (A), polyoxyethylene sorbitan monooleate (number of moles of ethylene oxide added 20) (B) and polyglyceryl stearate (average degree of polymerization of polyglycerin 3.81 per molecule) in the proportions listed in Table 4 average number of fatty acid residues in
1.5) (C), 10 parts by weight of propylene glycol, and pure water were added to make 100 parts by weight, and mixed and emulsified to prepare a sample. Table 4 shows the blending amounts of components (B) and (C), the blending ratio of components (A), (B), and (C), and the stability test results for each sample.

【table】

【table】

Claims (1)

[Scope of Claims] 1 (A) a long-chain aliphatic amine with 10 to 24 carbon atoms, (B) an ethylene oxide adduct of a long-chain fatty acid with 8 to 24 carbon atoms and a monoester of sorbitan (additional mole number of 10 to 24)
50) and (C) long chain fatty acids with 8 to 24 carbon atoms and degree of polymerization 2
A steam-based corrosion inhibitor composition comprising an aqueous emulsion containing ~15 esters of polyglycerol. 2. The composition according to claim 1, wherein the amount of component (A) is in the range of 0.5 to 20% by weight based on the total amount of the composition. 3. The composition according to claim 1 or 2, wherein the weight ratio of component (A) to the sum of components (B) and (C) is in the range of 1:1 to 1:7. 4. The composition according to any one of claims 1 to 3, wherein the weight ratio of component (B) to component (C) is in the range of 1:1 to 5:1.