Metal working fluid composition

Abstract

 A water-soluble metal-working composition is provided which comprises a relatively large alkoxylated amine, an alkanolamine and an acid-derived compound selected from organic acids, inorganic acids, and salts thereof.

Description

[0001] The present invention relates to water soluble metal-working compositions in general, and to water soluble lubricants and coolants in particular. Metal-working compositions of the present invention may be used in commercial applications, such as steel drilling, milling, tapping, grinding, boring, turning and cutting.

[0002] Several water-based metal-working fluid compositions are known in the art. U.S. Patent No. 2,917,160 to Turinsky relates to a water-soluble lubricating composition of an ethoxylated amine and a salt-forming acid, such as phosphoric acid or lactic acid. According to Turinsky, this lubricant composition should have a pH below 8, and is useful in water emulsions in a ratio of 1 part amine to 3 parts water. A similar aqueous cutting fluid is disclosed by U.S. Patent No. 3,186,946 to Sluhan. This cutting fluid consists of a tertiary ethoxylated amine in aqueous solution with boric acid to form an amine salt.

[0003] Other water-based metal-working compositions are known in the art. U.S. Patent No. 3,195,332 to Ranauto discloses an aqueous lubricant composition which includes a polyoxyethylene imidazoline. A corrosion inhibitor, such as sodium nitrite, triethanol amine or morpholine may also be included. U.S. Patent No. 2,990,369 to Shapiro discloses a metal-working lubricant specifically adapted for the cutting and grinding of titanium. This water-based lubricant composition comprises sodium fluoride, a high molecular weight imidazoline, a silicofluoride and a rosin amine ethylene oxide adduct.

[0004] U.S. Patent No. 3,265,620 to Heiman discloses an aqueous metal-working coolant comprising an ethanol amine, an alkali metal nitrite, and an aryl triazole which is at least one of benzotriazole and 4-nitrobenzotriazole. Heiman discloses that such compositions preferably should include a chelating agent, such as an amino polycarboxylic acid.

[0005] Another metal-working composition, which may be emulsified in water, is disclosed by U.S. Patent No. 4,185,485 to Schick et al. This composition includes an ester formed by reacting an alkenylsuccinic anhydride or acid with a hydroxy containing tertiary alkylamine, such as triethanol amine, or a hydroxy polyether amine. This composition may also contain a C₂-C₁₀ monocarboxylic acid. When the reaction product'is formed from an alkenylsuccinic anhydride or acid reacted with a hydroxy polyether amine, the composition may contain a rosin soap in addition to or instead of the monocarboxylic acid.

[0006] U.S. Patent No. 3,280,029 to Waldmann relates to a composition for improved lubricating oils and water-in- oil emulsions comprising alkyl amino monoalkanols, such as monoethyl aminoethanol, diethyl amino ethanol and diethyl amino ethoxy ethanol. U.S. Patent No. 4,043,925 to Felton relates to a water-based metal-forming composition comprising a block copolymer with a central portion of polypropylene oxide with polyethylehe oxide at each end, a sulfochlorinated fatty acid, an alkoxylated 1,5-aza pentane, and potassium hydroxide. U.S. Patent No. 4,329,249 to Forsberg relates to the formation of nitrogen-containing phosphorous-free carboxylic acid derivatives. These derivatives may be formed by reacting a carboxylic acid acylating agent with an alkylmonoalkoxy tertiary amine, and are useful for the incorporation of oil-soluble, water-insoluble functional additives into water-based functional fluids, such as water-based hydraulic fluids.

[0007] Other metal-working fluids, related in certain aspects to the metal-working fluid of the present invention, are disclosed by U.S. Patent Nos. 4,172,802 to Rieder, 4,177,154 to Chakrabarti, and 3,933,658 to Beiswanger et al. Further, a phosphoral tris(diethanolamide) additive is disclosed for water-based and ethylene-glycol based hydraulic fluids and lubricants in Wear, 50 (1978) 365-369, Ludomir, Tokarzewski, Zakrzew- ski, Wachowicz and Szczepaniak. Another phosphorus based metal-working composition is disclosed in Polish Patent Document No. 116,962 to Szczepaniak et al.

[0008] However, these metal working fluids may have some disadvantages which are obviated or minimized by the metal working fluid of the present invention. Unlike some metal working fluids which require that components react with each other to form the metal working fluid, the metal working composition of the present invention may be synthesized by merely mixing the components together.

[0009] Although many metal working fluids do not require that the components chemically react with each other, many compositions require a high proportion of relatively more expensive active ingredients to relatively less expensive ingredients, thereby increasing the cost of the metal-working composition.

[0010] Some metal working compositions may have the further disadvantage of requiring components which pose a potential health hazard to persons using them. For example, many metal working fluids used in the past contained nitrites, which have recently been recognized as participating in the conversion of certain chemical substances into carcinogens. For example, The United States Environmental Protection Agency recently promulgated a rule prohibiting the addition of nitrosating agents, such as nitrites, to triethanolamine salts of substituted organic acids when the mixture is to be used in metal working fluids due to the carcenogenic propensity of such materials demonstrated in animal studies (Federal Register, Vol. 49 No. 116, June 14, 1984, Rules and Regulations). This difficulty is avoided by the present invention, which exhibits good metal working properties without containing nitrosating agents.

[0011] In general, the present invention is a water-soluble, metal-working composition which includes a relatively large alkoxylated amine, an alkanol amine and an acid-derived compound, wherein the large alkoxylated amine is generally described by the formula:

Consistent with this formula, R₁ is selected from the group consisting of hydrogen, hydrocarbyl moieties, alkoxy moieties and polyalkoxy moieties, R₂ is selected from the group consisting of C₇ and larger hydrocarbyl moieties, and R₃ is selected from the group consisting of alkoxy moieties and polyalkoxy moieties.

[0012] The alkanol amine may generally be described by the formula:

R₄ is selected from the group consistent of hydrogen, C₁-C₆ hydrocarbyl moieties, and monomeric and polymeric alkoxy moieties consisting essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy and mixtures thereof. R₅ is selected from the group consisting of C₁-C₆ hydrocarbyl moieties, and monomeric and polymeric alkoxy moieties consisting essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy and mixtures thereof. R₆ is selected from the group consisting of monomeric and polymeric alkoxy moieties consisting essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy and mixtures thereof. R₄, R₅ and R₆ are additionally selected so that the alkanol amine contains a total of 6 or fewer alkoxy units.

[0013] The acid-derived compound included in the present invention is selected from the group consisting of inorganic acids, organic acids, and salts thereof.

[0014] The present invention is a water-soluble, metal-working composition comprising a relatively large alkoxylated amine, an alkanol amine and an acid-derived compound. According to the invention, the large alkoxylated amine is a relatively large amine which may be generally described by the formula:

R₂ is a relatively large hydrocarbon group selected from the group consisting C₇ and larger hydrocarbyl moieties. These hydrocarbyl moieties are generally alkyl or alkenyl in character, but may be an aryl moiety such as benzyl, methyl benzyl or dimethoxy benzyl, and alkyl phenyls such as nonyl phenyl. However, alkyl and alkenyl moieties are preferred. Polyalkoxy groups are not included. About C₁₂ to about C₂₀ hydrocarbyl moieties, such as stearyl, oleyl, palmyl, linoleyl, soya, lauryl, myristyl and tallow, are more preferred. Stearyl, oleyl, soya, coco and tallow moieties are most preferred.

[0015] R₁ is selected from the group consisting of hydrogen, hydrocarbyl moieties, alkoxy moieties and polyalkoxy moieties. The hydrocarbyl moieties may be aryl, alkyl or alkenyl in character, such as phenyl, stearyl, oleyl, soya, coco and tallow. Alkyl or alkenyl groups are preferred. Although R₁ may be selected independent of R₂, when R₁ is hydrocarbyl it is preferred that R₁ be the same as R₂ due to the relative cost efficiency of preparing the alkoxylated amine when, instead of being different hydrocarbyl moieties, both _R1 and _R2 are the same. Preferably, however, R1 is an alkoxy or a polyalkoxy moiety, consistent with those defined for R₃.

[0016] R₃ may only be selected from the group consisting of alkoxy and polyalkoxy moieties. Preferably, these alkoxy and polyalkoxy moieties consist essentially of alkoxy units generally described by the following formula. As will be understood by those pkilled in the art, the oxygen of alkoxy moieties and the terminal oxygen of polyalkoxy moieties is bonded to hydrogen, not shown in the above formula, to form a terminal hydroxy group.

[0017] R₇ is selected from the group consisting of hydrogen and C₁-C₂₈ hydrocarbyl moieties, such as alkyl groups like methyl, ethyl and propyl. More preferably, R₇ is hydrogen, methyl or ethyl, so that the alkoxy unit is an ethoxy, 2-propoxy or 2-butoxy unit, respectively. Ethoxy and propoxy units, wherein R₇ is hydrogen or methyl, respectively, are even more preferred. Although R₃ may be a polyalkoxy moiety consisting of a mixture of different alkoxy units, such as a mixture of ethoxy units and propoxy units, it is more preferred that R₃ be homogenous. Hydroxy ethyl and homogenous polyethoxy moieties are most preferred.

[0018] Although R₁ may be selected independently from R₃, when R₁ is an alkoxy or polyalkoxy moiety, it is preferred that R₁ consist essentially of at least some of the same alkoxy units as R₃ in order to simplify preparation of the tertiary alkoxylated amine. For example, when R₃ is a polyalkoxy moiety of mixed ethoxy and propoxy units, it is preferred that R be hydroxy ethyl, hydroxy propyl, polyethoxy, polypropoxy or a polyalkoxy moiety of mixed ethoxy and propoxy units. Similarly, when R₃ is a polyethoxy moiety, it is preferred that R₁ be hydroxy ethyl, polyethoxy or a mixed polyalkoxy moiety of ethoxy units and other alkoxy units. Most preferably, however, both R₁ and R₃ consist essentially of the same kind of alkoxy units.

[0019] In the preferred embodiment R₁ and R₃ are chosen such that the total number of alkoxy units in the large alkoxylated amine is equal to 2 to about 35. For example, the total number of alkoxy groups may be equal to 2 when each of R₁ and R₃ is hydroxy ethyl, or when R₃ is a polyethoxy moiety consisting of 2 ethoxy units and R₁ is hydrogen or a hydrocarbyl moiety such as tallow. More preferably, the total number of alkoxy units in said large alkoxylated amine is equal to about 5 to about 20, such as where R₃ is a polyethoxy moiety consisting of three ethoxy units, and R₁ is a polyethoxy moiety consisting of two ethoxy units. Relatively large alkoxylated amines consistent with the preferred embodiment of the invention are commercially available from the Borg_-Warner Corporation under the trademark "PEGAMEEN".

[0020] The alkanol amine of the present invention is a relatively small amine, and may be generally described by the formula:

[0021] R₄ is selected from the group consisting of hydrogen, C₁-C₆ hydrocarbyl moieties such as methyl, phenyl, ethyl, propyl and butyl, and monomeric and polymeric alkoxy moieties. When R₄ is a monomeric or polymeric alkoxy moiety, the alkoxy moiety consists essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy and mixtures thereof. For example, when R₄ is a monomeric alkoxy moiety, R₄ is selected from the group consisting of hydroxy ethyl(HO-CH₂CH₂-), 2-hydroxy propyl(CH₃CH(OH) CH₂ ), and 2-hydroxy butyl(CH₃CH₂CH(OH)CH_Z-) moieties. Although R₄ may be a polymeric alkoxy moiety, such as polyethoxy(HOCH2CH2OCH2-CH2-) or polypropoxy (CH₃CH(OH)-CH₂OCH(CH₃)CH₂-), R₄ preferably is a simple alkoxy moiety, such as hydroxy ethyl or 2-hydroxy propyl, a simple hydrocarbyl such as methyl, ethyl, or hydrogen, such as in dimethyl ethanol amine, N-phenyl ethanol amine, and N,N-diethyl ethanol amine. Hydroxy ethyl and hydrogen are most preferred, such as when the alkanol amine is triethanol amine, diethanol amine or N-methyl ethanol amine.

[0022] R_S may be selected from the group consisting of C₁-C₆ hydrocarbyl moieties, as discussed above for R₄, and monomeric and polymeric alkoxy moieties which consist essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy and mixtures thereof, as discussed above for R₄. However, unlike R₄, R₅ may not be hydrogen. Consequently, although the alkanol amine may be a secondary or tertiary amine, the alkanol amine may not be a primary amine. In the embodiment of the invention which is most preferred, R is methyl, as in N-methyl ethanol amine or dimethyl ethanol amine, or hydroxy ethyl, as in diethanol amine or triethanol amine.

[0023] R₆ may be a monomeric or polymeric alkoxy moiety consisting essentially of alkoxy units selected from the group consisting of ethoxy, 2-propoxy, 2-butoxy, and mixtures thereof, as discussed above for R₄. Preferably, R₆ is hydroxy ethyl or 2-hydroxy propyl. Hydroxy ethyl is more preferred. Triethanol amine, N-methyl ethanol amine and mixtures thereof are most preferred.

[0024] It should further be noted that although each of R₄₁ R₅ and R₆ may be a polymeric alkoxy group, the alkanol amine may contain no more than a total of 6 alkoxy units. However, fewer than 6 alkoxy units are preferred, such as in triethanol amine, diethanol amine and N-methyl ethanol amine, wherein the total number of alkoxy units is equal to or less than 3.

[0025] The composition of the present invention also contains an acid-derived compound. This acid-derived compound may be an organic acid, an inorganic acid or a salt derived from an organic or inorganic acid by the replacement of an acidic hydrogen by another appropriate cation. Preferred organic acid-derived compounds include acetic acid, propionic acid, butyric acid, formic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, benzoic acid, suberic acid, azelaic acid, para-toluene sulfonic acid, sebacic acid, and amino acids such as alanine, leucine, phenylalanine, glycine, tyrosine, serine, aspartic acid and glutamic acid.

[0026] In the embodiment of the invention which is most preferred, the acid-derived compound is an inorganic acid, with phosphoric acid, nitric acid and sulfuric acid being preferred. Boric acid is not preferred. Phosphoric acid is most preferred.

[0027] In an alternative embodiment which is less preferred than those discussed above, the acid-derived compound may be a salt of an organic or inorganic acid, and preferably is a salt of the preferred acids discussed above. When the acid-derived compound is a salt, it is preferred that the acid-derived compound be a Group VIII metal, alkaline metal, alkaline earth metal or amine salt. Examples of salts consistent with this embodiment include iron phosphates, ammonium sulfates and sodium nitrates.

[0028] It has been found that the composition of the present invention, as described, provides a metal-working composition in which time-consuming and costly component preparation may be avoided, and yet achieve excellent cooling, high lubricity, and extreme-pressure properties. Further, the composition of the present invention may exhibit high thermal and hydrolytic stability, while inhibiting the development of rust on the workpiece and equipment. Some formulations, such as those containing N-methyl ethanol amine as some or all of the alkanol amine component, may also exhibit a lowered susceptibility to the growth of mold and bacteria.

[0029] The ratio of the ingredients for optimum performance in a particular application, such as extreme-pressure properties, can be adjusted as needed. It is preferred, however, that the ratio by weight of the alkanol amine to the relatively large alkoxylated amine be about 20:1 to about 0.0.5:1. More preferably, however, the ratio by weight of the alkanol amine to the large alkoxylated amine is about 10:1 to about 0.1:1, with a ratio of about 7:1 to about 0.5:1 being most preferred. When the ratio of the alkanol amine to the relatively large alkoxylated amine is about 20:1 to about 0.05:1, it is preferred that the ratio by weight of the acid-derived compound to the large alkoxylated amine be about 3:1 to about 0.01:1. Ratios of acid-derived compound to large alkoxylated amine of about 1.5:1 to about 0.1:1, however, are more preferred.

[0030] Due to space and weight considerations, the composition of the present invention usually will be stored and shipped in a relatively concentrated form. Although this concentrate may contain no significant quantities of water, the composition usually will be shipped and stored as an aqueous solution which contains 10-60% by weight, and preferably 20-50% by weight, of the relatively large alkoxylated amine, the alkanol amine and the acid-derived compound combined.

[0031] Although the composition of the present invention may be used in a concentrated form, due to the fact that a significant portion of the cost of a lubricating composition generally is for the "active" components rather than the carrier medium, e.g. water or oil, it is generally preferred that the amount of metal-working composition in a lubricant or coolant be as low as practically possible. As suggested by the examples discussed below, the composition of the present invention may be used in the form of highly dilute aqueous solutions without adversely affecting the lubricity, extreme-pressure or anti-wear properties of the invention.

[0032] In the preferred embodiment, the composition is an aqueous solution which includes at least 85% by weight water, based on the total weight of the solution, and about 0.1 1 to 15% by weight of the combined large alkoxylated amine, alkanol amine and the acid-derived compound, although, as is known to those skilled in the art, the appropriate concentration will vary depending on the application. More preferably, however, the large alkoxylated amine, the alkanol amine and the acid-derived compound together constitute about 0.5 to about 10% by weight of the solution, with about 0.5 to 5% being most preferred.

[0033] It is further preferred that the pH of the composition be equal to about 7.5 to about 10.5 in order to minimize the corrosive effects of the composition on the workpiece; pH's in the range of about 8 to about 9.5 are more preferred. Consistent with the invention, pH's in the preferred ranges may be attained by adjusting the proportions of the various components to each other, and/or by adding other components, such as acids or bases, to maintain the proper pH balance. Other components may also be added to assist in solubilizing the composition in water, although these are not usually necessary. Other known additives, such as biocides, dyes, perfumes, antifoam compounds, crystal growth modifiers, scale inhibitors and chelating agents for hard water use may also be included.

SPECIFIC EMBODIMENTS

[0034] Reference is made to the following examples, which are provided to illustrate various aspects of the invention by embodifying certain aspects of the invention or by providing a basis for comparison.

[0035] Examples 1-28 illustrate the testing of various fluids to determine their load carrying properties by determining their maximum load to failure. Testing reported in Tables I and II was performed according to ASTM No. D 3233-73, "Standard Methods for Measurement of Extreme Pressure Properties of Fluid Lubricants (Falex Methods)".

[0036] Unless otherwise indicated, the lubricating fluids in these examples are fluids formed by placing the components indicated in deionized water. Amounts indicated are weight percent, based upon the total weight of the fluid. The term DEA indicates diethanol amine and TEA indicates triethanol amine.

[0037] Examples 1-7 represent various formulations of the preferred embodiment of the invention, wherein the solubilizing component is the inorganic acid, H₃P0₄. However, that the composition of the present invention is not limited to inorganic acids or H₃PO₄ in particular may be seen from Examples 21-28.

[0038] Comparative Examples C8-C12 represent testing of various commercially available metal-working compositions as a basis for comparing the composition of the present invention. In these and subsequent examples, Cim Cool 400 is a proprietary metal-working concentrate, for heavy machinery and grinding, of Cincinnati Milacron; Do-All is #470 soluble oil of Do-All Finishing Company; Antara HR-719 is a proprietary metal-working lubricant of GAF Corp.; E-Cool is a proprietary fluid from Henry E. Sanson & Sons, Inc., and Clear Mint is a concentrated, synthetic cutting lubricant, coolant and rust inhibitor from Amitron Products, Inc.

[0039] Comparative Examples C13-C20 represent testing of various components useful in making the composition of the present invention. In these and the following examples, H₃P0₄ is 85 wt% phosphoric acid aqueous solution. "PEGAMEEN" is a Trademark of Borg-Warner Chemicals, Inc. used in conjunction with amine compounds corresponding to relatively large alkoxylated amines useful in the present invention, according to the general formula discussed above, wherein R₁ is an alkoxy or polyalkoxy moiety. The numerical portion of the PEGAMEEN designation, such as T-7, T-15 and T-25, indicates the average value of the total number of alkoxy units in the large amine compound. Consequently, T-7 indicates an average value of 7, T-15 indicates an average value of 15, and T-25 indicates an average value of 25. In the examples presented herein, R₂ of the alkoxylated amine is a tallow moiety. The results of Examples 1-C20 are reported in Table I.

[0040] Examples 21-28 illustrate the effect of various inorganic acids, such as H₂SO₄ and boric oxide, which hydrolyzes to boric acid in the presence of water, carboxylic acids, and salts on the extreme-pressure test results conducted as described above. A series of compositions were prepared containing 0.4% by weight of Pegameen T-7, 2.0% by weight triethanol amine and various concentrations of different acids or salts. The acids or salts, their concentration and the extreme-pressure test results are indicated in Table II.

[0041] Performance of known metal-working fluids, as well as metal-working fluids consistent with the present invention, under drilling conditions, was assessed. Drilling was conducted using a steel workpiece of hardness index RC-29 according to The Rockwell C hardness scale, and a 1/4 in. black oxide coated drill at 1000 + 5 rpm with an 0.0052 in./revolution feed rate. Metal-working fluid was flooded onto the drill from two sides. Triadine 10, used in Example 40, is a biocide from Olin Corp. and Amine CS-1135, used in Example 41, is a corrosion inhibitor from the Angus Chemical _Co. The results of drill testing of fluids consistent with the composition of the present invention (Examples 35-41), and with other fluids tested to provide a basis for comparison (Comparative Examples C29-C34) are reported below in Table III. Although the workpieces for Comparative Examples C31-C33 exhibited extensive rusting after testing, significant corrosion was not evident on the workpieces for Examples 35-41, wherein water soluble metal working compositions of the present invention were used.

[0042] In addition to the examples described above, further testing indicates that- part or all of the alkanol amine may be N-methyl ethanol amine without degrading the metal working properties of the composition of the present invention.

Claims

1. A water soluble metal-working composition comprising:

(a) an alkoxylated amine of the formula:

wherein R₁ is hydrogen, hydrocarbyl, alkoxy or polyalkoxy, R₂ is hydrocarbyl of at least 7 carbon atoms and R₃ is alkoxy or polyalkoxy;

(b) an alkanolamine of the formula:

wherein R₄ is (i) hydrogen, (ii) C₁-C₆ hydrocarbyl or (iii) a monomeric or polymeric alkoxy moiety consisting essentially of alkoxy units selected from ethoxy, 2-propoxy and 2-butoxy, R₅ is (i) C₁-C₆ hydrocarbyl or (ii) a monomeric or polymeric alkoxy moiety consisting essentially of alkoxy units selected from ethoxy, 2-propoxy and 2-butoxy and R₆ is (i) a monomeric or polymeric alkoxy moiety consisting essentially of alkoxy units selected from ethoxy, 2-propoxy and 2-butoxy such that said alkanolamine contains 6 or fewer alkoxy units; and

(c) an acid-derived compound selected from organic acids, inorganic acids, and salts thereof.

2. A composition according to claim 1 wherein R₁ and _R3 independently represent a monomeric or polymeric alkoxy moiety consisting essentially of alkoxy units or mixtures of alkoxy units of the formula:

wherein R₇ is hydrogen or C₁-C₂₈ hydrocarbyl; R₁ and R₃ are being selected such that the total number of alkoxy units in said alkoylated amine is from 2 to 35.

3. A composition according to claim 2 wherein R₇ is hydrogen or methyl.

4. A composition according to claim 2 or 3 wherein the total number of alkoxy units in said alkoxylated amine is from 5 to 15 or 20.

5. A composition according to any one of the preceding claims wherein R₂ is C₁₂ to C₂₀ hydrocarbyl.

6. A composition according to claim 5 wherein R₂ is stearyl, oleyl, coco, soya or tallow.

7. A composition wherein R₅ is methyl, hydroxyethyl or hydroxypropyl and R₄ is independently selected from the same possibilities as R₅ and also hydrogen.

8. A composition wherein said acid-derived compound (c) is (i) an inorganic acid selected from H₃PO₄, H₂SO₄ and HN0₃, (ii) an organic acid selected from acetic, formic, propionic, oxalic, succinic, glutaric, adipic, pimelic, benzoic, suberic, azelaic,paratoluenesulfonic, sebacic and amino acids or (iii) a salt selected from Group VIII metal, alkali metal, alkaline earth metal, nitrate, sulfate, phosphate and amine salts.

9. A composition according to any one of the preceding claims wherein the weight ratio of the alkanolamine (b) to the alkoxylated amine (a) is from 20:1 to 0.05:1.

10. A composition according to claim 9 wherein the weight ratio is from 10:1 to 0.1:1.

11. A composition according to claim 9 wherein the weight ratio is from 7:1 to 0.5:1.

12. A composition according to any one of the preceding claims wherein the weight ratio of said acid-derived compound (c) to said alkoxylated amine (a) is from 3:1 to 0.01:1.

13. A composition according to claim 12-wherein the weight ratio is from 1.5:1 to 0.1:1.

14. A composition according to any one of the preceding claims which is in the form of an aqueous solution.

15. A composition according to claim 14 wherein the alkoxylated amine (a), alkanolamine (b) and acid-derived compound (c) together constitute 0.1 to 15% by weight of said solution.

16. A composition according to claim 15 wherein (a),(b) and (c) together constitute 0.5 to 10% by weight of said solution.

17. A composition according to claim 14,15 or 16 wherein said solution has a pH of 7.5 to 10.5.

18. A composition according to claim 17 wherein said solution has a pH equal of 8 to 9.5.

19. A composition according to any one of the preceding claims wherein the alkanolamine (b) is triethanolamine, diethanolamine or N-methyl ethanolamine.