EP0192358B1

EP0192358B1 - Metal working fluid composition

Info

Publication number: EP0192358B1
Application number: EP86300562A
Authority: EP
Inventors: Yuval Halpern; Lee Cherney
Original assignee: GE Chemicals Inc
Current assignee: GE Chemicals Inc
Priority date: 1985-02-04
Filing date: 1986-01-28
Publication date: 1991-01-02
Anticipated expiration: 2006-01-28
Also published as: KR860006535A; MX168689B; JPS61235499A; KR930007896B1; DE3676315D1; EP0192358A3; EP0192358A2

Description

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.
Several water-based metal-working fluid compositions are known in the art. US-A-2,917,160 relates to a water-soluble lubricating composition of an amine and a salt-forming acid, such as phosphoric acid or lactic acid. 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 US―A―3,186,946. This cutting fluid consists of a tertiary amine in aqueous solution with boric acid to form an amine salt.
Other water-based metal-working compositions are known in the art. US―A―3,195,332 discloses an aqueous lubricant composition which includes an aqueous lubricant composition which includes a polyoxyethylene imidazoline. A corrosion inhibitor, such as sodium nitrite, triethanolamine or morpholine may also be included. US―A―2,990,369 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.
US―A―3,265,620 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. Such compositions preferably should include a chelating agent, such as an amino polycarboxylic acid.
Another metal-working composition, which may be emulsified in water, is disclosed by US-A-4,185,485. This composition includes an ester formed by reacting an alkenylsuccinic anhydride or acid with a hydroxy-containing tertiary alkylamine, such as triethanolamine, or a hydroxypolyether amine. This composition may also contain a C27-Clo 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.
US―A―3,280,029 relates to a composition for improved lubricating oils and water-in-oil emulsions comprising alkyl amino monoalkanols, such as monoethyl ethanol-amine, diethyl ethanol-amine and diethyl ethoxyethanol amine. US―A―4,043,925 relates to a water-based metal-forming composition comprising a block copolymer with a central portion of polypropylene oxide with polyethylene oxide at each end, a sulfochlorinated fatty acid, an alkoxylated 1,5-aza pentane, and potassium hydroxide. US―A―4,329,249 relates to the formation of nitrogen-containing phosphorus-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.
Other metal-working fluids, related in certain aspects to the metal-working fluid of the present invention, are disclosed by US-A-4,172,802, US―A―4,177,154 and US-A-3,933,658. Further, a phosphoral tris(diethylamide) additive is disclosed for water-based and ethylene-glycol based hydraulic fluids and lubricants in Wear, 50 (1978) 365-369, Ludomir, Tokarzewski, Zakrzewski, Wachowicz and Szczepaniak. Another phosphorus based metal-working composition is disclosed in Polish Patent Document No. 116,962 to Szczepaniak et al.
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.
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.
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 carcinogenic propensity of such materials demonstrated in animal studies (Federal Register, Vo. 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.
The present invention provides a water-soluble, metal-working composition comprising:

(a) an amine of the formula:
wherein R₁ is hydrogen, hydrocarbyl, hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene), R₂ is C₁₂―C₂₀ hydrocarbyl and R₃ is hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene);
(b) an alkanolamine of the formula:
wherein R₄ is (i) hydrogen, (ii) C₁―C₆ hydrocarbyl or (iii) a hydroxyl-terminated group of the formula
wherein R is hydrogen, methyl or ethyl and n is at least 1, R₅ is (i) C₁-C₆ hydrocarbyl or (ii) a hydroxyl-terminated qrou_D of the formula
wherein R is hydrogen, methyl or ethyl and n is at least 1 and R₆ is (i) a hydroxyl-terminated group of the formula
wherein R is hydrogen, methyl or ethyl and n is at least 1 such that said alkanolamine contains at most 6 oxyalkylene groups of formula
and
(c) an organic or inorganic acid or salt thereof. R₂ is generally alkyl or alkenyl in character, but may be aryl or alkylphenyl such as nonyl phenyl. However, alkyl and alkenyl groups are preferred such as stearyl, oleyl, palmyl, linoleyl, soya, lauryl, myristyl and tallow, with stearyl, oleyl, soya, coco and tallow being most preferred.

R₁ is hydrogen, hydrocarbyl, hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene). 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 amine when, instead of being different hydrocarbyl moieties, both R₁ and R₂ are the same. Preferably, however, R₁ is hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene), consistent with those defined for R₃.
R₃ may only be hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene). Preferably, these moieties consist essentially of oxyalkylene units generally described by the following formula:-
wherein R₇ is hydrogen or C₁―C₂₈ hydrocarbyl, such as alkyl groups like methyl, ethyl and propyl, and n is at least one. More preferably, R₇ is hydrogen, methyl or ethyl, so that the alkoxy unit is hydroxyethyl, 2-hydroxypropyl or 2-hydroxybutyl. The first two of these are even more preferred. Although R₃ may be a moiety consisting of a mixture of different oxyalkylene units, such as a mixture of oxyalkylene units and oxypropylene units, it is more preferred that R₃ be homogeneous. Hydroxyethyl and poly(oxyethylene) moieties are most preferred.
Although R₁ may be selected independently from R₃, it is preferred that R₁ consist essentially of at least some of the same units as R₃ in order to simplify preparation of the amine (a). For example, when R₃ is a poly(oxyalkylene) moiety of mixed oxyethylene and oxypropylene units, it is preferred that R₁ be hydroxyethyl, hydroxypropyl, poly(oxyethylene), poly(oxypropylene) or a poly(oxyalkylene) moiety of mixed oxyethylene and oxypropylene units.
In the preferred embodiment R₁ and R₃ are chosen such that the total number of oxyalkylene units in the amine (a) is from 2 to 35. For example, the total number of oxyalkylene groups may be 2 when each of R₁ and R₃ is hydroxyethyl or when R₃ is a poly(oxyalkylene) moiety consisting of 2 oxyethylene units and R₁ is hydrogen or a hydrocarbyl moiety such as tallow. More preferably, the total number of oxyalkylene units in amine (a) is 5 to 20, such as where R₃ is a poly(oxyalkylene) moiety consisting of three oxyethylene units and R₁ is a poly(oxyalkylene) moiety consisting of two oxyethylene units. Amines for use as amine (a) consistent with the preferred embodiment of the invention are commercially available from the Borg-Warner Corporation under the trademark "PEGAMEEN".
The alkanolamine (b) is relatively small as compared with amine (a) and is of the formula:
wherein R₄; R₅ and R_a are as hereinbefore defined. When R₄ is C₁―C₆ hydrocarbyl it can be, for example, phenyl, ethyl, propyl or butyl. When R₄ is a group of formula
the oxyalkylene moiety consists essentially of oxyethylene, 2-oxypropylene and 2-oxybutylene units, or mixtures thereof. For example, when n is 1, R₄ is selected from hydroxyethyl(HO―CH₂CH₂―), and

moieties. Although R₄ may be a poly(oxyalkylene) moiety, such as
or
R₄ preferably is a simple oxyalkylene moiety, such as hydroxyethyl or 2-hydroxypropyl, a simple hydrocarbyl such as methyl or ethyl, or hydrogen, such as in dimethyl ethanolamine, N-phenyl ethanolamine, and N,N-diethyl ethanolamine. Hydroxyethyl and hydrogen are most preferred, such as when the alkanol amine is triethanolamine, diethanolamine or N-methyl ethanolamine.
R₅ may be C₁-C₆ hydrocarbyl or a group of formula
as discussed above for R₄. However, unlike R₄, R₅ may not be hydrogen. Consequently, although the alkanolamine (b) may be a secondary or tertiary amine, the alkanolamine may not be a primary amine. In the embodiment of the invention which is most preferred, R₅ is methyl, as in N-methyl ethanolamine or dimethyl ethanolamine, or hydroxyethyl, as in diethanolamine or triethanolamine.
R₆ is group of the formula
as discussed above for R₅. Preferably, R₆ is hydroxyethyl or 2-hydroxypropyl. Hydroxyethyl is more preferred. Triethanolamine, N-methyl ethanolamine and mixtures thereof are most preferred.
It should further be noted that although each of R₄, R_s and R₆ may be a hydroxyl-terminated poly(oxyalkylene) group, the alkanolamine may contain no more than a total of 6 oxyalkylene units. However, fewer than 6 oxyalkylene units are preferred, such as in triethanolamine, diethanolamine and N-methyl ethanolamine, wherein the total number of oxyalkylene units is equal to or less than 3.
The composition of the present invention also contains (c) 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 acids 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.
In the embodiment of the invention which is most preferred, the component (c) is an organic acid, with phosphoric acid, nitric acid and sulfuric acid being preferred. Boric acid is not preferred. Phosphoric acid is most preferred.
In an alternative embodiment which is less preferred than those discussed above, component (c) is a salt of an organic or inorganic acid, and preferably is a salt of the preferred acids discussed above. When (c) is a salt, it is preferred that it 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.
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 ethanolamine as some or all of the alkanolamine component, may also exhibit a lowered susceptibility to the growth of mold and bacteria.
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 alkanolamine (b) to the amine (a) be 20:1 to 0.05:1, more preferably 10:1 1 to 0.1:1, and most preferably 7:1 to 0.5: 1. When the ratio of the alkanolamine (b) to the amine (a) is 20:1 to 0.05:1, it is preferred that the ratio by weight of component (c) to the amine (a) be 3:1 to 0.01:1, more preferably 1.5:1 to 0.1:1.
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 (a), (b) and (c) combined.
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.
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 0.1 to 15%, more preferably 0.5 to 10% by weight, and most preferably 0.5 to 5%, by total weight of (a), (b) and (c), although, as is known to those skilled in the art, the appropriate concentration will vary depending on the application.
It is further preferred that the pH of the composition be 7.5 to 10.5, more preferably 8 to 9.5, in order to minimize the corrosive effects of the composition on the workpiece. 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

Reference is made to the following examples, which are provided to illustrate various aspects of the invention by embodying certain aspects of the invention or by providing a basis for comparison.
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)".
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 diethanolamine and TEA indicates triethanolamine.
Examples 1-7 represent various formulations of the preferred embodiment of the invention, wherein the solubilizing component is the inorganic acid, H₃PO₄. However, that the composition of the present invention is not limited to inorganic acids or H₃P0₄ in particular may be seen from Examples 21-28.
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.
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 amines compounds containing a relatively large hydrocarbyl group and useful as amine (a) in the compositions of the present invention, according to the general formula discussed above, wherein R₁ is a hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene) 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 oxyalkylene 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 is a tallow moiety. The results of Examples 1-C20 are reported in Table I.
Examples 21-28 illustrate the effect of various inorganic acids, such as H₂S0₄ 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 triethanolamine 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.
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 0.64 cm (1/4 in) black oxide coated drill at 1000±5 rpm with an 0.13 mm (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.
In addition to the examples described above, further testing indicates that part or all of the alkanolamine may be N-methyl ethanolamine without degrading the metal working properties of the composition of the present invention.

Claims

1. A water-soluble, metal-working composition comprising:

(a) an amine of the formula:

wherein R₁ is hydrogen, hydrocarbyl, hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene), R₂ is C₁₂―C₂₀ hydrocarbyl and R₃ is hydroxyalkyl or hydroxyl-terminated poly(oxyalkylene);

(b) an alkanolamine of the formula:

wherein R₄ is (i) hydrogen, (ii) C₁―C₆ hydrocarbyl or (iii) a hydroxyl-terminated group of the formula

wherein R is hydrogen, methyl or ethyl and n is at least 1, R₅ is (i) C₁-C₆ hydrocarbyl or (ii) a hydroxyl-terminated group of the formula

wherein R is hydrogen, methyl or ethyl and n is at least 1 and R₆ is (i) a hydroxyl-terminated group of the formula

wherein R is hydrogen, methyl or ethyl and n is at least 1 such that said alkanolamine contains at most 6 oxyalkylene groups of formula

and

(c) an organic or inorganic acid or salt thereof.

2. A composition according to claim 1 wherein R₁ and R₃ independently represent a hydroxyl-terminated group of the formula:

wherein R₇ is hydrogen or C₁-C₂₈ hydrocarbyl and n is at least 1; R₁ and R₃ being selected such that the total number of oxyalkylene groups of formula -(-O―CU―CH₂-)- in said amine (a) 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 oxyalkylene groups in said amine (a) is from 5 to 15 or 20.

5. A composition according to any one of claims 1 to 4 wherein R₂ is stearyl, oleyl, coco, soya or tallow.

6. A composition according to any one of the preceding claims wherein R₅ is methyl, hydroxyethyl or hydroxypropyl and R₄ is independently selected from the same possibilities as R_s and also hydrogen.

7. A composition according to any one of the preceding claims wherein (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.

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

9. A composition according to claim 8 wherein the weight ratio is from 10:1 to 0.1:1.

10. A composition according to claim 8 wherein the weight ratio is from 7:1 to 0.5:1.

11. A composition according to any one of the preceding claims wherein the weight ratio of (c) to said amine (a) is from 3:1 to 0.01:1.

12. A composition according to claim 11 wherein the weight ratio is from 1.5:1 to 0.1:1.

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

14. A composition according to claim 13 wherein (a), (b) and (c) together constitute 0.1 to 15% by weight of said solution.

15. A composition according to claim 14 wherein (a), (b) and (c) together constitute 0.5 to 10% by weight of said solution.

16. A composition according to claim 13, 14 or 15 wherein said solution has a pH of 7.5 to 10.5.

17. A composition according to claim 16 wherein said solution has a pH equal of 8 to 9.5.

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