GB2024855A - Metal Working Lubricants - Google Patents

Abstract

Metalworking lubricants comprise an ester formed by the reaction of an alkenyl succinic anhydride or acid in which the alkenyl group is derived from a C16-18 olefine or dimer thereof or C12-20 monocarboxylic acid or dimer thereof with a hydroxyamine. The lubricants may be emulsified, with water, and in this form are particularly suitable for can forming operations.

Description

SPECIFICATION Metal Working Lubricants This invention relates to lubricants which may be used in metal working, especially for forming aluminum cans and also for metal cutting. The invention is particularly applicable to emulsion type lubricants.

Modern can forming or other metal-working methods requiring emulsion lubricant use procedures that impose severe requirements on present lubricants. Certain metal working operations encountered in can forming e.g. cupping, drawing and ironing, require emulsions with special properties.

U.S. Patent No. 3,071,544 describes emulsions, primarily for rolling oils, containing components including a small amount of organic acid which may be reacted with other components, e.g.

alkanolamines, to provide oil soluble soaps. U.S. Patent No. 3,311 ,557 describes emulsions containing a fatty acid, a polyol and ethanolamine. The ethanolamine reacts with the acid to provide a ratio of base number to acid number of 0.15 to 0.4.

U.S. Patent No. 3,697.428 is concerned with an oil soluble composition made by reacting a polyolefin-substituted succinic anhydride and a di-or trihydric alcohol and polyhydric alcohol containing at least four hydroxyl groups. U.S. Patent No. 3,381,022 teaches ester derivatives of a hydrocarbonsubstituted succinic acid (in which the hydrocarbon is an aliphatic chain containing at least 50 carbon atoms) and a mono- or polyhydric alcohol, a phenol or a naphthol;They are useful as additives to hydrocarbon oils and lubricating compositions or fuels.

U.S. Patent Nos. 3,523,895; 3,723,314 and 3,723,313 disclose an emulsifiable oil containing acid, triethanolamine and oil.

We have now discovered that lubricants having high advantageous properties may be prepared with esters derived from certain hydroxyalkylamines. The hydroxyalkylamines are reacted with either an alkenyl succinic anhydride or a C12-C20 monocarboxylic acid or its dimer to produce a liquid product which may be blended with a lubricant vehicle. This composition may be used on its own or as an emulsifiable concentrate.

The essential constituent of the lubricant is a reaction product of either an alkenyl succinic acid or its anhydride with a tertiary amine having hydroxy functionality. Generally, the amine will contain 2 to 100 carbon atoms. As an alternative to the alkenyl succinic acid or anhydride it is possible to use a C12-C20 monocarboxylic acid or its dimer.

The alkenyl succinic acid or anhydride has an alkenyl substituent which is preferably derived from an olefin containing 16 to 28 carbon atoms. If desired, the olefine may be oligomerized to form a longer chain material e.g. a dimer containing 32-56 carbon atoms. Suitable olefin mixtures containing 1 6-28 carbon atoms are available in commerce and may be used for this purpose. Dimers of such mixtures are particularly useful; they may be produced by dimersing the initial olefine under suitable conditions of heat and catalyst which are well known in themselves.

In order to form the desired alkenyl succinic anhydride, the olefinic material is reacted with maleic anhydride. The reaction is generally carried out at elevated temperatures, e.g. 1 50# to 2500C and catalysts may be used, if desired, as is well known for this reaction. The anhydride which is obtained may, if desired, be hydrolyzed to form the corresponding acid and, if further desired, the alkenyl substituent hydrogenated to give a saturated side chain.

The alkenyl succinic anhydride or acid is then reacted with the hydroxyamine. The amine may be a simple tertiary hydroxyamine such as a trialkanolamine e.g. triethanolamine or tri-isopropanolamine, of which the former is preferred. The other preferred types of hydroxyamine are the alkylene oxide adducts of primary and secondary alkylamines in which the alkyl group contains 8 to 18 carbon atoms.

These materials have the formula:

where R is a C8 to C18 hydrocarbon group, preferably alkyl R' is a -(CH2CH2O) xCH2CH2OH or (CH2CH2CH2O)xCH2CH2CH2OH group R" is an R or R' group xisfrom 1 to 50.

These adducts may be prepared by reacting ethylene oxide or propylene oxide with the requisite primary or secondary amine. Suitable amines include octylamine, dodecylamine, hexadecylamine, stearylamine and oleylamine. The chain length of the polyoxyalkylene group may be altered as desired by varying the ratio of the alkylene oxide to the amine, greater amounts of oxide producing the materials of longer chain length. Adducts of this kind are available commercially e.g. the Ethomeen (trade mark) adducts of amines derived from natural sources e.g. polyoxyethylene adducts of soyamine.

As an alternative to the alkenyl succinic anhydride or acid it is possible to use a C12-C20 monocarboxylic acid or its dimer. Suitable acids include dodecanoic acid, hexadecanoic acid, stearic acid, oleic acid, linoleic acid and linolenic acid. The acid dimers are, however, preferred. These materials, which are commercially available (e.g. as the Empol (trade mark) dimer acids of Emery Industries Inc.)), are generally referred to as "dimer acid". They are produced by the polymerization of unsaturated fatty acids, such as oleic, linoleic or linolenic acids, at mid-molecule. The polymerization in products are liquids composed principally of the dimer with smaller amounts of the trimer and residual monomer. The dimers are characterized by carboxyl functionality and behave as dibasic acids.Some unsaturation is commonly encountered in these materials but it is believed to be sterically hindered as reactions at the sites of unsaturation proceed slowly and incompletely.

The reaction between the acid and the hydroxyamine (i.e. the hydroxy alkylamine or the hydroxypolyether amine) can be carried out at temperatures from 1000 to 300 , preferably 1 500C to 2500C and for a time sufficient to form the desired ester, usually 3 to 6 hours. The time and temperature of reaction depend in some measure upon the reactants selected. The product is an ester and to this end, the ratio of the reactants is chosen to produce either a full ester or half ester. The full ester is preferred. If the acid reactant is dibasic, as the alkenyl succinic materials and the dimer acids are, two molecular proportions of the amine are required in order to produce the full ester. If the half ester is desired, the relative amount of amine is reduced by half.

The reaction product may be blended with a lubricant vehicle in order to produce the concentrate or, alternatively, with water to produce the final emulsion. The lubricant is typically a mineral oil but synthetic materials may also be used, including synthetic hydrocarbon-oils e.g. hydrogenated polydecene (mainly dimer and trimer), synthetic esters such as the esters of neopentyl polyols with monobasic acids e.g. trimethylol propane esters of pelargonic acid or caprylic acid, and polyglycols. The polyglycols are a particularly preferred class of lubricant vehicles for preparing emulsions because they blend readily with water and can be readily washed off the workpieces, leaving no residue.They also have the good high pressure characteristics desirable in metal working lubricants The polyglycols are actually polyoxyalkylene glycols produced by the polymerization of alkalene oxides, especially ethylene oxide. Their molecular weight is generally in the region 500-2000. Suitable polyglycols are widely available commercially, e.g. the Ucon (trade mark) fluids produced by Union Carbide.

The amount of the lubricant vehicle is generally in the range of 1 to 90 weight percent of the concentrate, generally 1 to 50 percent. If a polyglycol is used as the lubricant vehicle it is preferably used in an amount of 5 to 30 percent of the concentrate.

A particularly preferred class of lubricant vehicles for certain purposes are the sulfurized mineral oils and sulfurized olefins. When these are used, they generally comprise 90 to 99 weight percent of the concentrate with the ester present in amounts from 1 to 10 weight percent. Compositions made with these sulfurized materials may be used without emulsification, for example, as cutting oils.

However, they may also be emulsified, as described further below.

Sulfurized mineral oils are produced, as is well known, by heating a mineral oil with sulfur. The sulfur content of the oil will generally be in the range of 0.5 to 5 weight percent, preferably 0.5 to 1 weight percent.

Sulfurized olefins are well known and are described, for example, in U.S. Patent No. 3,703,504 They may be obtained by sulfohalogenating an olefine with a sulfur halide in the presence of a catalytic quantity of a lower aliphatic alcohol or other appropriate catalyst to form a sulfohalogenated organic intermediate. The intermediate is then sulfurized and dehalogenated in the presence of a lower aliphatic alcohol by treatment with an aqueous alkali metal sulfide solution, which can be derived, for example, from a spent aqueous alkali metal hydroxide effluent from hydrocarbon purification) having a high combined sulfur content, to produce an organic sulfide of high sulfur content.

A wide variety of olefinic substances may be charged to the sulfochlorination reaction, including olefins having a single double bond with terminal or internal double bonds and containing from about 2 to 8 or more carbon atoms per molecule in either straight, branched chain or cyclic compounds. These olefins may be exemplified by ethylene, propylene butene-1, cis-and-trans-butene-2, isobutylene, diisobutylene, triisobutyiene, the pentenes, cyclopentene, the hexenes, cyclohexene, the octenes and decene-1. In general, C3-C6 olefins or mixtures thereof are preferred for the present purposes because the miscibility with oil is higher than for the corresponding propylene and ethylene derivatives even though the combined sulfur content of the product is lower.

These sulfurized materials may be used either on their own or, for example, with another lubricant vehicle. In particular, the sulfurized olefins may be used with a mineral oil vehicle. If they are used in this way, the sulfurized olefin may be used in an ~ amount from 1 to 50 weight percent, preferably 5 to 10 weight percent of the oil.

If the lubricant is to be used in the form of an emulsion, the ester, together with any lubricant vehicle which -may be present, is blended with water. The concentrate will !generally comprise 1 to 50 weight percent, preferably 3 to 20 weight percent of the final emulsion. In order to stabilise the emulsion a surfactant may be added: anionic cationic and non-ionic types are suitable, although the anionic are preferred. Among the anionic surfactants which may be used are the alkali metal petroieum sulfonates and the alkali metal salts or soaps of other long chain acids, both of natural and synthetic origin. A particularly preferred class are the alkali metal rosin soaps. These materials are the soaps derived from rosin acids which are derived from wood pulp production.The rosin acids are commercially available and are typically prepared from tall oil and comprise a mixture of oleic, linoleic.

and abietic acids. The potassium soaps are preferred.

The surfactant may be added to the concentrate and the concentrate emulsified with the water either at ambient temperature or moderately elevated temperatures e.g. 250 to 500 C. The amounts of surfactant used will vary according to the types of the concentrate and surfactant and the relative proportions of concentrate and water. Generally, 1 to 10 weight percent will be satisfactory. based on the weight of the concentrate.

Because the ester reaction product formed by the acid and the hydroxyamine contains amine functionality, it is possible to form the amine salts by reaction with acid. Preferred acids for this purpose are the C2-C10 monocarboxylic acids: acetic, propionic, butyric, pentanoic, octanoic and decanoic. Particularly, preferred are 2-ethylhexanoic acid, caprylic acid, caproic acid and pelargonic acid. The amount of acid used depends both upon the nature of the ester and the acid but as a general guide, the amount will be 0.5 to 15 weight percent of the lubricant (without water) preferably 5 to 10 weight percent. The ester may, depending upon the amount of acid used, be wholly or partly converted to the corresponding ester salt.

Corrosion inhibitors such as benzotriazole or tolutriazole may be used, particularly when this is necessary having regard to the nature of the workpiece or the tools being used. Boric acid may also be used for this purpose. Extreme pressure agents such as the acid phosphates may be used, e.g. dibutyl acid phosphate, dilauryl acid phosphates, di-oleyl acid phosphate. Mixtures of phosphates may be used e.g. mono oleyl phosphate and di-oleyl phosphate. Biocides such as formaldehyde may b#e added to the emulsion lubricants in order to prevent rancidity and fungal growth and the development of unpleasant odors: Example 1 Part 1: Preparation of Alkenyl Succinic Anhydride.

A mixture of maleic anhydride and a C18-C28 olefin mixture (1 :1 molar ratio) was stirred while heating to 2500C over a 2 hour period and held at 2500 for another 2 hours to give a C16-C18 alkenylsuccinic anhydride. The olefin mixture used in this preparation was the high boiling fraction derived from olefin oligomerization and had the following compositing: Table 1 Olefin (chain length) Wt. percent Other C16 2max.

C18 5--15 C20 42-50 C22 20-28 C24 6-12 C28 1-3 C28 2 max.

Alcohol 10 max.

Paraffin 5 max.

Iodine No. 74 min.

Peroxide ~ 10 ppm max.

Olefin types byNMR Vinyl 28-44 Branched 30--50 Internal 26-42 Average mol. wt. 325 Part 2: Preparation of Ester.

Five hundred grams (approx 1 mole) of the alkenyl succinic anhydride were mixed with 300 g (2 moles) of triethanolamine and the mixture stirred at 2600C for 5 to 6 hours. The product was an oily liquid.

Example 2 A mixture of 500 g (approx 1 mole) of the succinic anhydride of Example 1 and 1000 g (2 moles) of Ethomeen 5-1 5 (trade mark-a polyoxyethylene soyamine made by hydrolyzing soybean oil, converting it to the acid, forming the C16-C18 primary amine and reacting with 5 moles of ethylene oxide) was stirred at about 2600C over a 5 to 6 hour period to give the final product which was an oily liquid.

Example 3 Example 1 was repeated except that 1 50 g (1 mole) of triethanolamine was used in Part 2, to produce the half ester.

Example 4 The olefin mixture of Example 1 was dimerised and then reacted with maleic anhydride as previously described to give-an alkenyl succinic anhydride with an alkenyl substituent having an average chain length of about 40 carbon atoms. This anhydride was then reacted in a 1:2 molar ratio with triethanolamine to produce the final product which was a viscous, oily liquid.

Example 5 Example 4 was repeated except that the anhydride was reacted with the triethanolamine in a 1:1 molar ratio to give an oily, liquid product.

Example 6 The dimer acid of linoleic-acid (C36) was reacted with triethanolamine in a 1:2 molar ratio under conditions similar to those described in Example 1, to produce an oily, liquid product.

Evaluation of Products Evaluation 1 The products of Example 1 to 6 were mixed with a sulfurized mineral oil which had been prepared by heating elemental sulfur in mineral oil at 11 00C to give a sulfur content of the oil 0.69% by weight.

The blends, containing 10% of the products of the Examples and 90% of the sulfurized mineral oil, were then tested by the Tapping Efficiency Test, which measures their effectiveness as metal cutting fluids.

The procedure used in the Tapping Efficiency Test involves measuring the torque developed in an internal threading operation on SAE 1020 hot-rolled steel. Thirty torque values are obtained with the test fluid and compared with thirty reference fluid values to give the tapping efficiency according to the formula: Tapping Efficiency (%)=Avg. of 30 Reference Fluid Torque valuesx 100 Avg. of 30 Test Fluid Torque Values In the test, a series of holes is drilied in SAE 1020 hot-rolled steel. The holes are tapped in a drill press equipped with a table which is free to rotate about the center on ball bearings. A torque arm is attached to this "floating table", and the arm in turn activates a spring scale, so that the actual torque during the tapping with the oil being evaluated is measured directly.The same conditions used in evaluating the test oil are employed in tapping with a "standard", which has arbitrarily been assigned an efficiency of 100%. The average torque in the test standard is compared with that of the standard and a relative efficiency is calculated on a percentage basis.

Table 2 below summarizes the tapping efficiency data obtained. The data was based on MOBILMET-27 (trade mark-a cutting oil containing sulfurized fat and phosphosulfurized oxidized mineral oils, with a pour point of -1 0C a flash point of 1 800C and a viscosity of 160 SUS at 380C. The sulfurized mineral oil alone was used as a blank.

TABLE 2 Fluid Efficiency { /OJ Reference 100 Blank (sulf. mineral oil) 76 Blank+Example 1(10%) 114 Blank+Example 3 (10%) 98 Blank+Example 4 (10%) 100 Blank+Exampie 5(10%) 131 Blank+Example 6(10%) 80 Evaluation 2 The product of Example 1 was evaluated in the Tapping Efficiency Test when blended with a 1 00 SUS solvent-refined, paraffinic neutral oil (90% oil, 10% Example 1 product).The results were as follows: TABLE 3 Fluid Efficiency (%J Blank (oil) 53 Blank+Example 1(10%) 61 Evaluation 3 Emulsifiable concentrations were made up as follows (weight percent): Composition 1 Wt. percent Example 1 product 68 Caprylic acid 4 2-Ethylhexanoic acid 4 Tolutriazole 4 Polyglycol (1) 20 100 Compositlon 2 Wt. percent Example 1 product 68 Caprylic acid 8 Tolutriazole 4 Polyglycol (1) 20 100 Composition 3 Example 2 product Rosin acid salt (2) 95 Notes: (1) Ucon 50 HB55 (trade mark of Union Carbide) (2) Potassium salt of rosin acid, principally abietic acid.

These compositions were then tested in aluminum can forming operations as follows: A sheet of aluminum 0.38 mm thick was coated with a lubricant comprising water and 3.0% or 6.0% of the above compositions and was fed to a cupper. The formed cups retain the 0.38 mm thickness on bottoms and sides. From here, the cups were fed to body maker where they were formed into a container having sides 0. 13 mm thick and 0.38 mm bottoms. The formed cans were fed to a multistage washing unit where they were washed with a solution containing water, sulfuric acid, hydrofluoric acid and a surfactant. They were then washed with water and given a conversion coating.

Table 4 below summarizes the results.

Table 4 Performance Test Composition 1 Composition 2 ~ Composition 3 Cupper (Minster Single Feed) Good cup at 3% Good cup at 6% Good cup at 6% Pick-up Slight at 1.5% None Slight at 3% Body maker (Bliss Single Feed) Good cans at 3% ~ Good cans at 3.75% Washer: acid Water break conversion Clean conversion - Clean at 380C coating coating only With respect to Composition 3, good cups were made at 6% concentration using 108 kg. hold down pressure; 95 kg hold-down pressure resulted in some wrinkles.

Again with respect to Composition 3, approximately 1 50 cans were drawn and ironed at 3.75% using 13.6 kg blow-out pressure. The finish was good, with no observable bodymaker grease on the dies.

Evaluation 4 Emulsifiable concentrates were made of the product of Example 1 with various carboxylic acids to produce the ester salts. The concentrates were then formulated into emulsions containing 97% water and 3% concentrate. These emulsions were then tested in the Tapping Efficiency Test using as a reference fluid a conventional emulsion lubricant containing mineral oil and sodium sulfonates at 3% concentration (97% water, 3% oil). The results are shown in Table 5 below.

Table 5 Emulsifiable Concentrate Example 1 Acetic Caprylic 2-Ethyl-hexanoic Tapping Product (wt O/ol Acid (wt /OJ Acid (wt %) Acid (wt. O/oJ Efficiency (%) 90 10 ~ ~ 238 90 ~ 10 ~ 472 90 ~ ~ 10 292 Evaluation 5 Emulsifiable concentrates were made up as follows: Composition 4 Wt. percent Example 2 product 100 Composition 5 Wt. percent Example 2 product 90 Potassium rosin soap (2) 10 Composition 6 Wt. percent Example 2 product 80 Polyglycol (1) 20 Composition 7 Mit. percent Example 2 product 76 Polyglycol (1) 19 Potassium rosin soap (2) 5 Notes: (1), (2) Same as in Evaluation 3 above.

These concentrates were emulsified to form lubricants containing 97% water and 3% concentrate. These lubricants were then tested in the Tapping Efficiency Test and the Hard Water Stability test. The reference for the Tapping Efficiency Test was the same 97:3 emulsion used in Evaluation 4. The Hard Water Stability Test was carried out for 24 hours at 21 C, using water containing 500 ppm CaCO3. The results are as shown in Table 6 below: Table 6 Hard Tapping Water Concentrate Efficiency (%) Stability Composition 4 113 Separation Composition 5 114 No Separation Composition 6 145 Separation Composition 7 108 No Separation These results show that the potassium rosin soap is particularly effective in preventing separation in hard water.

The Hard Water Stability test is carried out by mixing one part of the lubricant with 5 parts of hard water and storing the mixture in a 100 ml graduated cylinder for 24 hours at 21 C. At the end of this period the mixture is observed for separation.

Evaluation 6 Composition 1 was formulated into a lubricant containing 97% water and 3% of Composition 1.

This lubricant was tested, along with other lubricants in the Instron (trade mark) Can Forming Performance Test. This test requires a 6.35 mm steel ball to be pushed through a 6.15 mm hole in an aluminum plate of 3.17 mm thickness. Six values are obtained for each lubricant. Values below 272 kg are normally required for high performance products. The results are shown in Table 7 below.

Table 7 Lubricant Force (keg) None 425 Paraffinicoil 100 SUS 277 Soluble oil (1) 281 Composition 1 lubricant 208 Note: (1) Sulfonate emulsifiers, 60% oil at 3% concentration in water.

Claims (14)

Claims

1. A metalworking lubricant which comprises an ester formed by reacting (i) an alkenylsuccinic anhydride or acid in which the alkenyl group is derived from an C16-C26 olefin or a dimer thereof or a C12-C20 monocarboxylic acid or a dimer thereof with (ii) a hydroxy amine.

2. A lubricant according to claim 1 in which the hydroxy amine comprises a hydroxy-substituted tertiary amine.

3. A lubricant according to claim 2 in which the hydroxy amine comprises triethanolamine.

4. A lubricant according to claim 1 in which the amine comprises a hydroxy polyetheramine of the formula:

where R is a C8 to C18 hydrocarbon group R' is (CH2CH2O)xCH2CH2OH or (CH2CH2CH2O)xCH2CH2CH2OH Rn is R or R' xis 1 to 50.

5. A lubricant according to any of claims 1 to 4 which includes a polyglycol.

6. A lubricant according to claim 5 in which the amount of polyglycol is from 5 to 30 weight percent.

7. A lubricant according to any of claims 1 to 4 which includes a sulfurised olefin or sulfurised mineral oil in amount from 0.5 to 95 weight percent.

8. A lubricant according to any of claims 1 to 7 which includes a surfactant.

9. A lubricant according to claim 8 in which the surfactant comprises an alkali metal rosin soap.

10. A lubricant according to any of claims 1 to 9 which includes a C2-C# monocarboxylic acid.

11. A lubricant according to claim 10 in which the C2-C10 monocarboxylic acid comprises caprylic acid.

12. A lubricant according to any of claims 1 to 11 which is in the form of an aqueous emulsion.

13. A lubricant according to claim 12 in which the emulsion comprises water and 3 to 20 weight percent of the specified components.

14. A metalworking lubricant substantially as described in the foregoing Examples.