GB2048262A

GB2048262A - Polycarboxylic Acid/Amine Salts and Aqueous Systems Containing Same

Info

Publication number: GB2048262A
Application number: GB8012434A
Authority: GB
Original assignee: Lubrizol Corp
Current assignee: Lubrizol Corp
Priority date: 1979-04-16
Filing date: 1980-04-15
Publication date: 1980-12-10
Also published as: ES490557A0; FR2454472B1; GB2048262B; JPS565984A; ES8104433A1; FR2454472A1

Abstract

Inhibitors useful in preventing the corrosion of metal surfaces that contact aqueous systems containing them are disclosed. They comprise salts of polycarboxylic acids and monoamines. Typical corrosion inhibitors are made from acids such as sebacic and azelaic acid and monoamines such as ethanol amine, di- and tri-ethanol amines and N,N- diethyl-ethanol amine.

Description

SPECIFICATION Polycarboxylic Acid/Amine Salts and Aqueous Systems Containing Same Background of the Invention 1. Field of the Invention This invention relates to corrosion inhibitors which prevent corrosion of metal surfaces contacted by aqueous compositions containing them. More particularly it relates to corrosion inhibitors which are amine salts of certain polycarboxylic acids and certain mono amines. it also relates to aqueous systems containing the aforedescribed corrosion inhibitors and methods of inhibiting corrosion of metal which comprises contacting metal with said aqueous systems.

2. Prior Art It is known to treat aqueous systems, such as functional fluids (e.g., machining and hydraulic fluids), with corrosion inhibitors to prevent unwanted corrosion of metal surfaces which come in contact with the systems. For example, more or less strongly alkaline systems are used for temporary corrosion inhibition during the production of metal work pieces, during or after cleaning treatments and during machining or at other stages of processing. Typical known corrosion inhibitors used in such systems are the alkali metal nitrites and chromium salts. Organic compounds such as alkanol amines, particularly tri(alkanol) amines and alkyl or alkanol amine soaps of fatty acids have also been used.

The system containing nitrites and chromates have the disadvantage that special steps must be taken to prevent their release into waste water without removal of the nitrites or chromates. In addition, certain nitrite-containing materials have been suspected of carcinogenicity. Alkanol amines and fatty acid salts have frequently been found to be inadequate corrosion inhibitors requiring the use of excessive levels or supplementary additions of chromate or nitrite.

Therefore the need for effective, nonpolluting corrosion inhibitors for aqueous systems has continued.

Efforts to meet this need have resulted in research described in several patents. For example: U.S. Patent 4,1 1 3,498 discloses corrosion inhibitors comprising a reaction product of an aliphatic carboxylic acid, a polyhydroxy carboxylic acid and an alkanol amine.

U.S. Patent 4,053,426 and British Patent Specification 1,532,836 describe water-based, metal working fluids containing amine salts of a partial ester of an alkenyl or alkyl succinic acid.

Japanese Patent Application 156,684, as abstracted in Derwent publications abstract number 59567A/33*j5 3079-738, discloses water-soluble corrosion inhibitors for steel containing a carboxylic acid and an amino alcohol.

U.S. Patent 2,726,215 discloses alkali and alkaline earth metal salts of dicarboxylic acids and their use in aqueous systems as corrosion inhibitors.

U.S. Patent 2,638,449 discloses reaction products of fatty acids and dialkanol amines which are further reacted with alkenyl succinic acids having substituents of up to 31 carbon atoms.

U.K. Patent application 1,521,984, as abstracted in Derwent publications, abstract number J501 4W-52, describes detergents made by reacting adipic or sebacic acid with mono-, di- or tri-ethanol amine and adjusting the pH of the reaction product to 7-7.5 with amine.

The product is described as being soluble in water.

U.S. Patent 4,120,665 describes water-soluble complex salts of certain metals, hydroxycarboxylic acids and phosphoric esters of alkanol amines and their use as corrosion inhibitors.

Summary of the Invention It has now been found that useful inhibitors of metal corrosion for use in aqueous systems comprise at least one water-soluble, mono amine carboxylate salt made from at least one polycarboxylic acid (I) corresponding to the formula: R(COOH)23 (I) wherein R is an alkylene or monohydroxy alkylene group of about 4 to about 1 5 carbons and from at least one mono amine (II) corresponding to the formula: (R')3N (II) wherein each R' is independently hydrogen, C12o hydrocarbyl or a C22o hydroxyl hydrocarbyl group, at least one R' being other than hydrogen.

Generally these ammonium carboxylates can be represented by the generic formula:

wherein R and R' are as disclosed above, n is an integer of two or three, m is an integer of one to three with the proviso that n is greater than or equal to m. Generally these mono amine salts are made in the absence of other carboxylic acids, specifically in the absence of other monocarboxylic acids.

Aqueous systems containing the aforedescribed inhibitors and methods of inhibiting corrosion of metal using them are also in the scope of the invention.

The inhibitor salts of this invention are water soluble; this means they have a solubility in water at 250C of at least 0.1 gm per liter.

Detailed Description of the Invention The Polycarboxylic Acid (I): The polycarboxylic acids used to make the inhibitors of the present invention can be represented by the formula: R(COOH)2-3 (I) wherein R is an alkylene, alkenylene, alkynylene, or hydroxyl alkylene group of about 4 to about 1 5 carbons. Typical alkylene groups are the butylene groups such as the 1,2-, 1,3- and 1,4-normal butylene groups, the branched butylene groups and higher homologs thereof up to groups containing about 1 5 carbons. Often R is an unbranched polymethylene group such as 1,5pentylene group, 1 ,6- hexylene group, 1 ,7- heptylene group, etc.

Usually, the acid is a dicarboxylic acid although tricarboxylic acids are useful.

The alkenylene groups which can be R are analogous to the alkylene groups except they contain a double bond. The hydroxyl alkylene groups which can be R are similarly analogous to the alkylene groups except a single hydroxyl group is also present in them.

Typically R is an unbranched polymethylene group; often it is an alkylene group of 4 to 10 carbon atoms or a polymethylene group of similar size. Specific examples of the acid (I) are sebacic, azelaic, 1 ,2,4- dodecanetrioic acid and the like.

Mixtures of two or more such acids can also be successfully used.

The Monoamine (all): The monoamines useful in making the carboxylate salts of this invention can be represented by the general formula (R1)3N (II) wherein each R' is independently hydrogen, a C12o hydrocarbyl or a C22o hydroxyl hydrocarbyl group, at least one R' being other than hydrogen.

Typically, at least one R' is a hydroxyl alkyl group.

Sometimes it is a di- or tri- (hydroxyl alkyl) group.

Specific examples of such hydroxy alkyl amines are ethanol amine, di-ethanc- amine, tri-ethanol amine, propanol amine, di(propanol) amine, tri(propanol) amine, N,N-di(lower alkyl) ethanol or propanol amine (where the alkyl group has up to seven carbon atoms) and the like. With the propanol amines, both the 1,2 and 1,3- isomers are contemplated.

In the invention's broader scope, the monoamine (II) can be aliphatic, alicyclic, aromatic or heterocyclic in nature. These include aliphatic-substituted aromatic, aliphaticsubstituted alicyclic, aliphatic-substituted aromatic, aliphatic-substituted heterocyclic, alicyclic-substituted aliphatic, alicyclicsubstituted aromatic, alicyclic-substituted heterocyclic, aromatic-substituted aliphatic, aromatic-substituted alicyclic, aromaticsubstituted heterocyclic, heterocycl ic-substituted aliphatic, heterocyclic- substituted alicyclic, and heterocyclic-substituted aromatic amines which may be saturated or unsaturated. If unsaturated, the amine will be free from acetylenic unsaturation (i.e., -C=-C-).

Aliphatic monoamines include mono-, di- and tri-aliphatic substituted amines wherein the aliphatic groups can be saturated or unsaturated and straight or branched chain. Thus, they are primary, secondary or tertiary aliphatic amines.

Such amines include, for example, mono, di- and tri-alkyl-substituted amines, mono-, di- and trialkenyl-substituted amines, and amines having one or two N-alkenyl substituents, one or two Nalkyl substituents and the like. The total number of carbon atoms in these aliphatic monoamines will normally not exceed about 40 and usually not exceed about 20 carbon atoms. Specific examples of such monoamines include ethyl methyl amine, diethyl amine, n-butyl amine, di-nbutylamine, tri-n-butyl amine, allyl amine, isobutyl amine, cocoamine, stearyl amine, lauryl amine, methyl lauryl amine, oleyl amine, N-methyl Noctyl amine, dodecyl amine octadecyl amine, and the like.Examples of alicyclic-substituted aliphatic amines, aromatic-substituted aliphatic amines, and heterocyclic-substituted aliphatic amines, include 2-(cyclohexyl)-ethyl amine, benzyl amine, phenyl ethyl amine, 3-(furylpropyl)amine and the like.

Alicyclic monoamines are those monoamines wherein there is an alicyclic substituent attached directly to the amino nitrogen through a carbon atom in the cyclic ring structure. Examples of alicyclic mono-amines include cyclohexyl amine, cyclopentyl amine, cyclohexenylamine, cyclopentenylamines, N-ethyl-cyclohexyl amine, dicyclohexyl amine, and the like. Examples of aliphatic-substituted, aromatic-substituted, and heterocyclic-substituted alicyclic monoamines include propyl-substituted cyclohexyl amines, phenyl-substituted cyclopentyl amines, and pyranyl-substituted cyclohexyl amine.

Suitable aromatic amines include those monoamines wherein a carbon atom of the aromatic ring structure is attached directly to the amino nitrogen. The aromatic ring will usually be a mononuclear aromatic ring (i.e., one derived from benzene) but can include fused aromatic rings, especially those derived from naphthylene.

Examples of aromatic monoamines include aniline, di(para-methylphenyl) amine, naphthyl amine, N-(n-butyl) aniline, and the like. Examples of aliphatic-substituted, alicyclic-substituted, and heterocyclic-substituted aromatic monoamines are para-ethyl aniline, para-dodecyl aniline, cyclohexyl-substituted naphthyl amine, and thienyl-substituted aniline.

Heterocyclic mono-amines can also be used in" making the carboxylate salts of this invention. As used herein the terminology "heterocyclic monoamine(s)" is intended to describe those heterocyclic amines containing at least one primary or secondary amino group and at least one nitrogen as a heteroatom in a heterocyclic ring. Heterocyclic amines can be saturated or unsaturated and can be substituted with alkyl, alkenyl, aryl, alkaryl or aralkyl substituents.

Generally, the total number of carbon atoms in the substituents will not exceed about 20.

Heterocyclic amines can contain heteroatoms other than nitrogen, especially oxygen and sulfur.

Obviously they can contain more than one nitrogen heteroatom. The five- and six-membered heterocyclic rings are preferred.

Among the suitable heterocyclics are aziridines, azetidines, azolidines, pyrrolidine, pyridine, tetra- and di-hydro pyridines, pyrroles, indoles, quinoline, picolines, piperidine and the like. Mixtures of two or more of these heterocyclic amines can be used. Typical heterocyclic amines are the saturated 5-and 6-membered heterocyclic amines.

As will be appreciated by those of skill in the art, when the monoamine (II) is an alicyclic or heterocyclic amine, two (or more) of the R' groups can be joined together. As noted above hydroxyl substituted analogs of all the above-described monoamines can be also used in the invention.

Similarly mixtures of such analogs and mixtures of one or more analogs with one or more of the above-described monoamine can be used.

The Reaction of the Polycarboxylic Acid (I) and the Monoamine (II) The inhibitor salts of this invention are formed by neutralizing the acid (I) with the amine (II). This neutralization can be carried out in a separate step before formulation of the aqueous system or it can be in situ during formation of the system by adding the acid(s) and the amine(s) to the system.

Usually the free acid is used although metal salts can be used especially when the amine (II) is in the form of an ammonium salt of a mineral acid.

The reaction generally takes place in water but its presence is not essential; other solvent/diluents can be used such as lower alkanols, ethers and the like.

Usually about one mole of amine (Il) is reacted with about one equivalent of acid (I) (an equivalent of acid is its molecular weight divided by the number of carboxylic groups in its structure). In determining acid equivalent weight, an anhydride group, if present, is counted as two carboxylic acid groups. As little as about 0.5 mole acid, as much as about 2.0 mole of amine (II) per equivalent of acid (II) can be used.

The aqueous systems of the present invention contain a corrosion inhibiting amount of at least one of the inventive carboxylate salts. Mixtures of two or more salts can, of course, be used.

Generally a corrosion inhibiting amount is at least as much as about 0.01 weight percent of the system and as much as up to the saturation point of the inhibitor salt(s) in the aqueous system.

The aqueous systems of the present invention may also contain other additives when this appears desirable. In some cases it is advisable to add surfactants which may encourage cleaning and degreasing effects and insure satisfactory wetting of surfaces being treated with the system.

The amount of surfactant used depends to some extent on its effectiveness but it may be up to 50% of the aforedescribed inhibitor salts.

Generally the inhibitor salts of this invention are used to inhibit corrosion of ferrous metals and alloys containing such metals.

When a light alloys or nonferrous metals are to be treated with the systems of this invention it may be useful to use special inhibitors for the metals in question. For example, alkali borates or condensed phosphates are known to protect aluminum against attack. Benzotriazole or derivatives or analogs thereof protect nonferrous metals against attack. In certain cases it may also be desirable to add appropriate bacteriocide or fungicides to protect the aqueous systems from attack from bacteria or fungi. Various agents-are known for these purposes, for example phenol derivative compounds which yield formaldehyde, triazines and quaternary ammonium compounds.

Other desirable additives for the sytems of this invention are known to those of skill in the art.

The following examples more fully describe the inhibitor salts of the present invention and show how they are used. These examples are intended to be merely illustrative and should not be construed as being limiting in any way. All parts and percentages are by weight, unless otherwise specified, and all temperatures are in degrees centrigrade.

Example 1 A mixture of 20.2 parts sebacic acid, 12.2 parts water and 14 parts ethanol amine is heated with intermitent agitation for 30 minutes at 800.

A clear yellow liquid containing 70 percent of the desired salt is obtained.

Example 2 A mixture of 29 parts suberic acid, 20.4 parts ethanol amine and 21.3 parts water is heated at 800C for one hour with intermitent agitation. A clear yellow liquid containing 70% of the desired salt is obtained.

Example 3 A mixture of 1 8.8 parts azelaic acid, 13.2 parts water and 12.2 parts ethanol amine is treated in the same fashion as Example 1 to yield a 70% solution of the desired salt.

Example 4 A mixture of 27 parts pimelic acid, 20.4 parts ethanol amine and 20.3 parts water is treated in the same manner as Example 2 to yield a 70% solution of the desired salt.

Example 5 A mixture of 149 parts water and 79 parts di(ethanol)amine is heated to 6070 . Then 70.5 parts azelaic acid is slowly added. The resulting mixture is heated for 0.5 hour to produce a 50% solution of the desired salt. When tested in the filter paper rust test at 1 percent in water only 1 rust spot was observed.

Example 6 To a mixture of 51.25 parts benzyl tri(methyl) ammonium hydroxide (40% in methanol) and 27 parts water is added 12.5 parts azelaic acid over a 0.5 hour period. The resulting mixture is a methanol/water solution containing approximately 40% of the desired salt.

Example 7 A mixture of 105.2 parts di(octadecenyl)amine (sold by the Armac Company as Armeen 2S) and 125 parts diluent oil. To this mixture is added 1 9.8 parts of azelaic acid. The resulting mixture is then heated at 65--750 for 8.5 hours. The product is a 50% oil solution of the desired salt.

Example 8 A mixture of 40 parts isopropanol amine, 80 parts water and 40 parts sebacic acid is stirred until solids disappear. The resulting aqueous salt solution has a pH of 9.0-9.5.

Example 9 A mixture of 40 parts isopropanol amine, 80 parts water and 40 parts 1,2-dodecanedioic acid is stirred until homogeneous to provide a solution of the desired salt.

Example 10 The desired inhibitor salt is formulated in situ during preparation of an aqueous concentrate useful for making a machining fluid through dilution. To 1000 parts water is added 9 parts hydroxyethyl cellulose thickener, 30 parts diethanol amine and 75 parts Emulan SH, a nitrogeneous fatty acid condensate product available as a corrosion inhibitor from the BASF Corporation of West Germany. Then the following ingredients are added in the order given: (A) A mixture of 0.75 part polypropylene glycol and 1.5 parts Molyvan L, a molybdenum dithiophosphate anti-wear agent.

(B) A mixture of 1.5 parts polyethylene glycol, 1.5 parts Anglamol 32,1.5 ports Lubrizol 5315 and 1.5 parts tributyl tin oxide. The Anglamol 32 and Lubrizol 531 5 are commercially available antiwear agents sold by The Lubrizol Corporation.

(C) A mixture of 132 parts tri(ethanol)amine, 31 parts Dequest 2010 o commercially available water softening agent having the formula

21 parts sebacic acid and 150 parts water.

(D) A slurry of 9 parts carboxymethyl cellulose and 15 parts ethylene gylcol. This mixture is stirred for 0.5 hour and then 2.25 parts defoamer and 4 parts isopropyl alcohol is added. Finally, silicone is added to make the entire mixture 1 500 parts. The mixture's pH is 8.5 and it exhibits satisfactory antirust performance in the Filter Paper Chip Test.

The efficiency of the inhibitor salts of the present invention can be demonstrated by their performance in the Filter Paper Chip Test.

Basically, this test involves placing steel millings saturated with test fluid on a 7 centimeter filter paper disc. After 24 hours the millings are removed and the paper is examined for rust stains. The number and size of the stains reflect the performance of the inhibitor. The steel millings are approximately 6 millimeters long and 1.5-3 millimeters wide and are prepared by drymilling of BS En 8 steel. These millings are washed in acetone and allowed to dry in air. They are then mixed with approximately 5 grams of test fluid with care being taken to thoroughly wet the millings and remove any air bubbles. The fluid containing the millings is then passed through a stainless steel perforated strainer and the wet millings deposited on a filter papered disc, sitting on a glass plate. Care is taken to spread the millings out in a single layer. The test area is then covered with a glass dish and left undisturbed for 24 hours. The covering dish is then removed as are the millings and the paper is allowed to dry and then inspected for rust stains.

The inhibitor-salts of this invention also perform successfully in the International Petroleum IP-25 rust test procedure.

The invention in its broader aspects is not limited to the specific details shown and described above and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

Claims

1. An inhibitor of metal corrosion for use in aqueous systems comprising at least one watersoluble ammonium carboxylate salt made from at least one polycarboxylic acid (I) corresponding to the formula R(COOH)2-3 (I) wherein R is an alkylene, alkenylene, alkynylene or hydroxyl alkylene group of about 4 to about 15 carbons, and from at least one monoamine (il) corresponding to the formula (R1)3N (II) wherein each R' is independently hydrogen, a C1~20 hydrocarbyl or a C220 hydroxyl hydrocarbyl group, at least one R' being other than hydrogen.

2. An inhibitor as described in claim 1 wherein the polycarboxylic acid (I) is a dicarboxylic acid and R is an unbranched polymethylene group.

3. An inhibitor as described in claim 2 wherein at least one of R' is a hydroxyl alkyl group.

4. An inhibitor as described in claim 3 wherein R is an alkylene group of about 4 to about 10 carbon atoms.

5. An inhibitor as described in claim 4 wherein the acid (I) is sebacic, azelaic, dodecanedioic acid or mixtures of two or more of these.

6. An inhibitor as described in claim 5 wherein the amine (II) is ethanol amine, diethanol amine, triethanol amine, propanol amine, di(propanol)amine, tri(propanol)amine, N,Ndi(lower alkyl)ethanol or propanol amine or mixtures of two or more of these.

7. An inhibitor as described in claim 6 wherein the acid (I) is sebacic acid and the amine (II) is ethanol amine, N,N'-di(ethyl)ethanol, and mixtures thereof.

8. A water soluble ammonium carboxylate represented by the formula

wherein R is alkylene, alkenylene or hydoxyl alkylene group of about 4 to about 1 5 carbons, each R' is independently, hydrogen, a C1~20 hydrocarbyl, or a C220 hydroxyl hydrocarbyl group, at least and R' being other than hydrogen, n is an integer of two or three, m is an integer of one to three, and n is greater than or equal to m.

9. An aqueous system containing a corrosion inhibiting amount of at least one metal corrosion inhibitor as described in claim 1.

10. An aqueous system containing a corrosion inhibiting amount of at least one metal corrosion inhibitor as described in claim 2.

11. An aqueous system containing a corrosion inhibiting amount of at least one metal corrosion inhibitor as described in claim 4.

1 2. An aqueous system containing a corrosion inhibiting amount of at least one metal corrosion inhibitor as described in claim 6.

1 3. An aqueous system containing a corrosion inhibiting amount at least one metal corrosion inhibitor as described in claim 7.

14. A system as described in claim 9 wherein the corrosion inhibiting amount is at least about 0.01 weight percent of the system to the saturation point of the inhibitor in the system.

1 5. A system as described in claim 10 wherein the corrosion inhibiting amount is at least about 0.01 weight percent of the system to the saturation point of the inhibitor in the system.

16. A system as described in claim 11 wherein the corrosion inhibiting amount is at least about 0.01 weight percent of the system to the saturation point of the inhibitor in the system.

1 7. A system as described in claim 11 wherein the corrosion inhibiting amount is at least about 0.01 weight percent of the system to the saturation point of the inhibitor in the system.

1 8. A system as described in claim 13 wherein the corrosion inhibiting amount is at least about 0.01 weight percent of the system to the saturation point of the inhibitor in the system.

1 9. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 9.

20. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 12.

21. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 13.

22. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 14.

23. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 1 5.

24. A method of inhibiting metal corrosion which comprises contacting the metal with the aqueous system described in claim 17.

25. A method of inhibiting the metal corrosion which comprises contacting the metal with the aqueous system described in claim 17.

26. The invention in all its novel aspects.