JPH0128834B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to corrosion inhibitors for non-mineral oil systems, and more specifically, for glycol-based, glycol-water-based,
Non-mineral oil-based brake fluids such as glycol ether and polyglycol ether-based brake fluids, flame-retardant hydraulic fluids,
This relates to corrosion inhibitors used in antifreeze, grease, etc. Various types of corrosion inhibitors for metals have been proposed, including those based on inorganic compounds and those based on organic compounds, and many of them are commercially available. However, most of the corrosion inhibitors based on inorganic compounds, for example, are limited to use in water systems.
Its use in non-mineral oil systems is not possible due to its solubility. In addition, organic compound-based corrosion inhibitors may be used only for specific metals or under specific usage conditions.
For example, only under relatively mild corrosive environments,
Its corrosive effect is recognized. Japanese Patent Publication No. 49-6022 proposes an oil-soluble rust preventive composition effective for iron using a polycarboxylic acid or a partial ester thereof and an aliphatic tertiary amine in a mineral oil system.
Further, in Japanese Patent Publication No. 53-35549, a partial ester amine salt is used in an aqueous or mineral oil system and is recognized to have a rust-preventing effect particularly on iron metals. However, in the case of non-mineral oil-based brake fluid systems, a wide variety of metals are used, including copper, brass, steel, cast iron, aluminum alloys, tin plated steel sheets, and galvanized steel sheets, and each metal is a dissimilar metal. It is a corrosive environment where contact corrosion is likely to occur between In particular, galvanized steel sheets are highly corrosive, and it is difficult to prevent such corrosion using conventional organic compound-based corrosion inhibitors. In view of this fact, the present inventor has conducted extensive research in order to obtain a corrosion inhibitor that can prevent contact corrosion between dissimilar metals in non-mineral oil systems and suppress corrosion of highly corrosive materials such as galvanized steel sheets. As a result, we have finally completed the present invention. That is, the present invention provides a partial ester of an unsaturated polybasic acid having 8 or more carbon atoms and a saturated alcohol having 8 or more carbon atoms, or an inorganic basic compound or A composition obtained by adding an amine compound,
The present invention relates to a corrosion inhibitor for non-mineral oil systems, which contains 0.1 to 10.0% by weight of an alkali metal salt of boric acid or metaboric acid and/or 0.01 to 1.0% by weight of a chelating agent, if necessary. . The unsaturated polybasic acids used in the corrosion inhibitor of the present invention include aliphatic and aromatic carboxylic acids having 8 or more carbon atoms and having two or more carboxyl groups, and polycarboxylic acids having hydroxyl groups. At this time, unsaturated polybasic acids having 7 or fewer carbon atoms have poor corrosion inhibiting effects. Examples of unsaturated polybasic acids include hexenylsuccinic acid, decenylsuccinic acid,
dodecenyl succinic acid, pentadecenyl succinic acid,
Maleated oleic acid, maleated castor oil fatty acid, maleated tall oil fatty acid, maleated rosin, phthalic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid or each isomer thereof, nuclear substituted product thereof, or acid anhydride thereof etc. can be given. The saturated alcohol, which is one component of the partial ester, must have 8 or more carbon atoms;
The following saturated alcohols do not provide sufficient corrosion prevention effect. Examples of saturated alcohols include 2-
Ethylhexanol, n-octanol, decanol, dodecanol, tridecanol, pentadecanol, hexadecanol, octadecanol, coconut oil reduced alcohol which is a mixed alcohol with 8 or more carbon atoms, beef tallow reduced alcohol, synthetic alcohol containing isomers etc. can be given. The partial ester of the present invention can be prepared by known methods. That is, a partial ester is obtained by heating and reacting a saturated alcohol and an excess unsaturated polybasic acid without a catalyst or in the presence of a catalyst such as an acid or a metal oxide, and then removing unreacted substances. In this case, the partial ester can be prepared even more easily if an anhydride of an unsaturated polybasic acid is used.
The unsaturated polybasic acid and the saturated alcohol can be used alone or in a mixture of two or more. Furthermore, in consideration of the solubility of the corrosion inhibitor in the application medium and the balance of corrosion prevention effect on ferrous metals and non-ferrous metals, the inorganic basic compound should be blended in an amount of 0.05 to 0.5 equivalents, and the amine compound should be blended in an amount of 0.5 to 1.0 equivalents. desirable. Inorganic basic compounds that can be used include:
There are alkali hydroxide compounds, alkali carbonate compounds, alkali phosphate compounds, alkali polyphosphate compounds, ammonium compounds, etc. Examples include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, tripotassium phosphate, sodium tripolyphosphate, Examples include ammonia and ammonium hydroxide. Furthermore, examples of the amine compound include aliphatic, aromatic, and heterocyclic amines. Examples include: mono-, di- and trimethylamine; mono-, di- and triisopropylamine; mono-, di- and tributylamine; mono-, di- and triamylamine; mono-, di- and trihexyl. Amines; mono- and dioctylamine; mono- and didodecylamine; mono- and dicoconutamine; mono- and dioleylamine; dimethyllaurylamine; dimethylcoconutamine;
Dimethyloleylamine; tallow amine; morpholine; N-methylmorpholine; piperidine; piperazine; piperazine-piperidone; N-ethylpyrrolidone; mono- and dicyclohexylamine;
Mono-, di- and triethanolamine; mono-, di- and triisopropanolamine; toluidine; xylylamine; xylene diamine;
Examples include diphenylamine; ethylenediamine; diethylenetriamine; triethylenetetramine; N-tallow propylene diamine and derivatives thereof (for example, alkylene oxide adducts). Alkali metal salts of boric acid or metaboric acid are
It is effective in preventing corrosion of ferrous metals, and by blending it, a non-amine corrosion inhibitor can be prepared. Examples of the compound include sodium borate, potassium borate, sodium metaborate, potassium metaborate, etc., and the blending amount thereof is 0.1 to 10.0% by weight, preferably 1.0 to 7.0% by weight.
Weight%. Further, the alkali metal salt of boric acid or metaboric acid can be easily blended if it is dissolved in ethylene glycol (at a concentration of 25% by weight or more). By incorporating a chelating agent, it is possible to further improve the corrosion prevention effect of various metals including galvanized steel sheets, and further improve the surface gloss. As the chelating agent, ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, and their sodium, potassium, ammonium, and amine salts can be used, and the blending amount thereof is 0.01 to 1.0% by weight. and preferably 0.05~
It is 0.1% by weight. When using the corrosion inhibitor according to the present invention, good results are obtained when the concentration of the active ingredient is generally about 0.1 to 5.0% by weight, preferably 0.5 to 3.0% by weight. It is also possible to add various kinds of rust preventive agents, antioxidants, lubricants, viscosity modifiers, etc. to the corrosion inhibitor of the present invention. Next, the present invention will be specifically explained with reference to Examples. Example 1 Using a brake fluid base containing ethyl carbitol as a main component, the partial esters shown in Table 1 were dissolved to an active ingredient concentration of 1.0% by weight, and the JIS
A corrosion test was conducted according to the brake fluid corrosion test method of K2233. The increase in corrosion is the amount per ^cm2 of the test piece.
Expressed in mg. Example 2 A corrosion test was conducted under the same conditions as Example 1 using a brake fluid base containing ethyl carbitol as the main component, in which the anticorrosive agent shown in Table 2 was dissolved at an active ingredient concentration of 1.0% by weight. I did this. The results are shown in Table 2. Example 3 Example 1 was prepared by dissolving the anticorrosive agent shown in Table 3 in a brake fluid base containing ethyl carbitol as a main component to an active ingredient concentration of 1.0% by weight.
A corrosion test was conducted under the same conditions as above, and the appearance of the galvanized steel sheet after the test was observed. This result is the third
Shown in the table. Example 4 Adding the anticorrosion agent shown in Table 4 to ethylene glycol
For those dissolved at a concentration of 2.0% by weight, JIS
A corrosion test was conducted according to the antifreeze corrosion test method of K2234. The results are shown in Table 4. The increase/decrease in corrosion was expressed in mg/cm ² of the test piece.

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Claims (1)

[Claims] 1. For a partial ester of an unsaturated polybasic acid having 8 or more carbon atoms and a saturated alcohol having 8 or more carbon atoms, or the remaining carboxyl group of the partial ester
If necessary, 0.1 to 10.0% by weight of an alkali metal salt of boric acid or metaboric acid and/or a chelating agent are added to a composition obtained by adding 0.01 to 1.0 equivalents of an inorganic basic compound or an amine compound.
A corrosion inhibitor for non-mineral oil systems, characterized by containing 0.01 to 1.0% by weight.