GB1592270A

GB1592270A - Lubricants for use in the hot-forming of metals

Info

Publication number: GB1592270A
Application number: GB54205/77A
Authority: GB
Original assignee: Dynamit Nobel AG
Current assignee: Dynamit Nobel AG
Priority date: 1977-01-03
Filing date: 1977-12-29
Publication date: 1981-07-01
Also published as: PL111766B1; SU683635A3; DE2700040A1; IT7847505A0; JPS5385751A; FR2376206A1; IT1155752B; PL203777A1; BE862599A; NL7800049A; SE7800020L; DD134545A5; CS195348B2; DE2700040C2

Description

(54) LUBRICANTS FOR USE IN THE HOT-FORMING OF METALS (71) We, DYNAMIT NOBEL AKTIENGESELLSCHAFT, a German Company, of 521 Troisdorf, Near Cologne, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to lubricants for the hot-forming of metal. In particular the invention relates to aqueous, non--environmentally-injurious lubricants which are suitable for non-cutting metal working, for example rolling or drawing, and which ensure an adequate lubricating or separating effect between the tools used and the materials to be deformed.

Hitherto known lubricants, for example those based on tars or mineral oils, have disadvantages. The continuous cooling of the tools with water, in the case of hot rolling mills with large quantities of water, causes cracking products and undecomposed mineral oil components to pass into the coolant circuit. The separation of substances which are not biologically easily degradable and which would pollute the waste water gives rise to considerable costs and adversely affects the economy of the method.

Tar and mineral oil products decompose thermally as a result of high temperatures of the work pieces, at the same time forming considerable clouds of smoke and soot which have to be disposed of for reasons of hygiene in the working area. This also involves considerable capital expenditure.

After short periods of operation, lubricant covers the fittings and frames in the form of a thin film which can only be removed wtih difficulty. Smooth objects covered with oil can interfere with the course of operation and cause accident through sliding or slipping.

It is therefore desirable to provide a lubricant for the hot-forming of metals, in particular for the hot-rolling of steel, which avoids the disadvantages of known lubricants based on mineral oils, which permits problem-free application with customary fittings such as pumps and nozzles, which shows good film formation on the tools used and which displays excellent adhesion after application to damp metal surfaces, even when the tools are cooled by running water.

According to the present invention, there is provided a lubricant for use in the hot-forming of metals comprising an aqueous emulsion of from 5 to 60% by weight of (a) a mixture of (i) a fatty acid monoglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group and (ii) a fatty acid diglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group, and/or (b) a fatty acid polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of fatty acid; the amount of the polyoxyalkylene compound or compounds present in the emulsion, the polyoxyalkylene chain length of the polyoxyalkylene compound or compounds present in the emulsion, the fatty acid chain length of the polyoxyalkylene compound or compounds present in the emulsion and/or the fineness of the emulsion being such that the emulsion has a viscosity of 5,000 to 40,000 cP measured in the manner described herein at a shear gradient of 2.64 cm-l and at a temperature of 30"C.

The invention also provides a method of hot-forming metal, wherein the hotforming is carried out in the presence of a lubricant of the invention. The invention further provides metal which has been hot-formed by the method.

The mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound preferably contains from 3 to 5 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group, and the fatty acid polyoxyalkylene compound preferably contains from 2.5 to 4 moles of radicals derived from alkylene oxide per mole of fatty acid.

As the polyoxyalkylene compounds, those obtained from ethylene oxide or propylene oxide are preferred, but those obtained from other alxylene oxides can be used.

Fatty acid polyoxyalkylene compounds and mixtures of fatty acid monoglyceride polyoxyalkylene compounds and fatty acid diglyceride polyoxyalkylene compounds are known and are prepared by direct reaction of fatty acids or mixtures of fatty acid monoglyceride and diglyceride with alkylene oxide, as a result of which there are formed, predominantly by reaction of the alkylene oxide with the carboxy groups of the fatty acid or by reaction of the alkylene oxide with the hydroxy groups of the glycerides of the mixture, linked oxyalkylene groups terminated by a hydrogen atom.

Preferred are mixtures of (a) a mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound and (b) a fatty acid polyoxyalkylene compound, in particular those with at least 10% by weight, preferably at least 20% by weight, of each of the two components (a) and (b).

Mixtures of different mixtures of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound and mixtures of different fatty acid polyoxyalkylene compounds can be used. As mixtures of fatty acid monoglyceride and fatty acid diglyceride, there may be used mixtures free of triglycerides or with reduced contents of triglycerides and whose content of monoglycerides and diglycerides does not normally vary from 30 to 100% by weight, preferably 55 to 90% by weight.

The fatty acid radicals of the glycerides or fatty acids can be saturated or unsaturated. Radicals of hydroxy-fatty acids should not be present.

Lubricants containing fatty acid polyoxyethylene compounds are disclosed in German Offenlegungsschrift No. 2,446,319, but these lubricants, for a purpose posing different problems, are water-soluble lubricants which, when diluted with water, form true transparent or semi-transparent solutions. The lubricant solutions in accordance with German Offenlegungsschrift No. 2,446,319 are disadvantageous because of their low viscosity and consequently low degree of adhesion to the tools. The lubricants are washed from tools cooled with running water and are thus unsuitable for lubrication of such tools. A further disadvantage of the lubricants in accordance with German Offenlegungsschrift No. 2,446,319 is their complicated preparation from three components, namely (A) a water-soluble substance with a fairly long polyoxyalkylene chain, (B) an oil-soluble substance with a fairly short polyoxyalkylene chain and (C) a surface-active agent. The task of the present invention could not be solved by German Offenlegungsschrift No. 2,446,319.

The emulsion of the invention preferably contains 10 to 40% by weight of the polyoxyalkylene compound or the mixture of polyoxyalkylene compounds, increasing quantities thereof increasing the viscosity so that it is possible to adjust the viscosity. A second possible means of adjusting the viscosity is by the length of the polyoxyalkylene chain, longer polyoxyalkylene chains in many cases reducing the viscosity. Further influences on the viscosity are the fineness of the emulsion, the chain length of the fatty acids and the content of monoglyceride polyoxyalkylene compound and diglyceride polyoxyalkylene compound in the mixture thereof, so that it is not possible to forecast with sufficient accuracy the viscosity of the aqueous emulsions from chemical analysis thereof. Therefore, the desired specific viscosity of a specific product is adjusted, if necessary after measuring the viscosity of the ingredients, to the viscosity specified for the particular application by simply mixing emulsions having high viscosities with emulsions having low viscosities.

Preferred degrees of polyoxyalkylene substitution are from 3 to 5 moles of radicals derived from alkylene oxide per poiyoxyalkylene-substituted hydroxy group of the monoglyceride and diglyceride in the case of the mixtures of fatty acid diglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound, and, in the case of the fatty acid polyoxyalkylene compounds, from 2.5 to 4 moles of radicals derived from alkylene oxide per mole of fatty acid.

The emulsions have the considerable advantage of forming spontaneously. It has been found that aqueous emulsions of a mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound having a degree of polyoxyalkylene substitution less than 2 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group and/or a fatty acid polyoxyalkylene compound containing less than 2 moles of radicals derived from alkylene oxide per mole of fatty acid, do have adequate adhesion to damp metal surfaces, for example water-cooled rollers, but that there is no guarantee of the formation of a uniform lubricant film. At points which are particularly smooth or are heavily subjected to the action of water, the film is torn away resulting in increased wear on the tool. Aqueous emulsions of mixtures of fatty acid monoglyceride polyoxyalkylene compound and fatty acid di glyceride polyalkylene compound and/or fatty acid polyoxyalkylene compounds with a degree of polyoxyalkylene substitution of more than 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group or fatty acid, on the other hand, display poor adhesion to damp metal surfaces so that it is not possible reliably to apply the lubricant film, for example, by directing it through nozzles onto rotating water-sprayed rollers, since the lubricant film is quickly washed away.

It has been found that the lubricant in accordance with the invention must have a viscosity of from 5,000 to 40,000 cP, preferably from 10,000 to 30,000 cP, measured under the specified conditions. All viscosity measurements herein, including those of the Examples and Comparison Examples hereinbelow, were made on the rotational viscosimeter "Rotovisko" made by Gebruder Haake KG and, unless otherwise stated, were measured at a shear gradient of 2.64 cm'-' and at a temperature of 30"C, the shear gradient being an apparatus constant of the "Rotovisko", the value of this apparatus constant being dependent upon the dimensions of the cylinders of the "Rotovisko". The temperable couette device MV II P was used in combination with the measuring element 500 which, due to its special shape is particularly suitable for testing emulsions. Details may be obtained from the trade pamphlet "Rotovisko, Beschreibung und Gebrauchsanleitung", Druckschrift 105/lib, and from the article by W. Heinz in "Rheologie und Rheometrie mit Rotationsviskometern", 2nd ed., Springer-Verlag, Berlin.

Lubricants having viscosities below 5000 and above 40,000 cP are not suitable for use according to the invention even when polyoxyalkylene compounds the same as or similar to those used in accordance with the invention are contained therein. Lubricants with viscosities below 5000 cP display inadequate adhesion to damp metal surfaces and can thus not be used in practice. An upper limit to the viscosity range of the lubricant in accordance with the invention results from the fact that conveyance and application of the aqueous emulsion must be possible with usual operational devices such as pumps, nozzles, and the like. Moreover, viscosities above 40,000 cP are undesirable for the additional reason that difficulties are encountered in uniformly applying the lubricant film.

The lubricant in accordance with the invention has a so-called plastic viscosity behaviour. Linked with this is the presence of a flow limit which exceeds the value 50 dyne . cm 2 (obtained by the expansion method after 30 seconds expansion time).

In accordance with this behaviour a decrease in viscosity is observed as the shear gradient increases. Thus, the lubricant in accordance with the invention has a viscosity between 100 and 500 cP at a shear gradient of 428 cm 1 and a temperature of 300C.

Adjustment of the viscosity can be effected by varying the concentration of the mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound and/or the fatty acid polyoxyalkylene compound.

Thus, emulsions with a higher polyoxyalkylene compound content generally display a higher viscosity, and vice-versa. The desired viscosity of the aqueous emulsions can, however, also be brought about my mixing, for example, two polyoxyalkylene compounds or mixtures of polyoxyalkylene compounds, one of which when used alone results in a low viscosity in the emulsion and the other of which when used alone results in a high viscosity.

The fatty acid radicals of the polyoxyalkylene compounds used in the lubricant in accordance with the invention preferably derive from fatty acids containing from 12 to 22 carbon atoms, for example lauric, myristic, palmitic, stearic, palmitoleic, oleic, linoleic, linolenic, arachidonic and erucic acid, or from mixtures of such fatty acids, preferably mixtures of fatty acids with 16 to 22 carbon atoms. The preparation of the polyoxyalkylene compound can be effected particularly advantageously using natural raw materials such as, for example, palm oil, peanut oil, cotton seed oil, soya bean oil, sunflower oil, linseed oil, rape seed oil, lard, beef tallow, whale oil and herring oil. The mixtures of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound can be prepared in accordance with known methods, for example by transesterification of the aforementioned fats or oils with glycerine or by esterification of fatty acids obtained by dissociation of fats with glycerine and subsequent polyoxyalkylene substitution with the specified quantities of alkylene oxide. The fatty acid polyoxyalkylene compounds can be prepared by for example the addition of alkylene oxide to fatty acids obtainable by dissociation of fats, or by esterification of fatty acids with a polyalkylene glycol of appropriate chain length.

The preparation of the lubricant in accordance with the invention is effected by mixing the mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound and/or the fatty acid polyoxyalkylene compound with water. Since the emulsion is formed spontaneously further measures, for example homogenisation after mixing are not necessary. The aqueous emulsions thus obtained can be used directly after preparation but, since they display good stability, can also be stored for a fairly lengthy period, for example several weeks, substantially unchanged. In the latter case, it is expedient to prevent microbial decomposition by the addition of a customary preservative. Furthermore, if necessary, further additives such as anticorrosives, vapour phase inhibitors, antioxidising agents and the like can be incorporated in small quantities into the lubricant in accordance with the invention.

When using a fatty acid polyoxyalkylene compound without any mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound, it is expedient to include a small quantity of a sodium or potassium salt of a fatty acid having 12 to 22 carbon atoms in the emulsions. This facilitates the formation of the emulsion, and the application of the oil film is effected more evenly.

The lubricant in accordance with the invention satisfies demands which increasingly have to be placed on the use of substances in the industrial field for reasons of environmental protection. Thus, solely due to the use of, for example, a 25% emulsion in accordance with the invention a reduction of the organic material to a quarter, as compared with the use of a lubricant based on mineral oil, can be obtained.

The lubricant in accordance with the invention can be satisfactorily biologically degraded so that residues passing into waste water cause only slight pollution. Since, for example in the hot rolling of steel the majority of the organic material bums off upon evaporation of the water issuing from the roller gap, the amounts of organic material pollutant are extremely small. With the use of the lubricant in accordance with the invention a considerable reduction in soot and smoke formation can be obtained in comparison with the behaviour of substances containing mineral oils.

Smells such as occur when using systems containing mineral oil due to the formation of offensive-smelling cracking products, does not occur in use of the lubricant in accordance with the invention.

The lubricant in accordance with the invention displays excellent adhesion to damp metal surfaces, and therefore, although dispersible or emulsifiable in water, it can be applied to water-cooled rollers, a uniform lubricant film being formed. On the other hand, lubricant residues which may possibly have been deposited during application, particularly when the lubricant is applied by spraying, on the roller frames and fittings, can be removed in simple manner completely and without problem, for example by being rinsed off with a powerful jet of water.

A preferred use for the lubricant in accordance with the invention is in the hotrolling of steel. In this instance it forms an even lubricant film, and has good adhesion to the rollers and an adequate lubricating and separating effect.

The lubricant in accordance with the invention will now be illustrated by the following Examples. Unless otherwise stated, "percentages" are "percentages by weight".

In Example 19, reference is made to the "iodine number", this being a criterion for double bond content determined in accordance with DGF-unit methods (see "Deutsche Gesellschaft fir Fettwissenschaft" Sections D-IV 2b (61) and C-IV 4A (52)).

Comparison Example 1.

25 parts of a mixture of 46% of fatty acid monoglyceride polyoxyethylene compound and 50% of fatty acid diglyceride polyoxyethylene compound, derived from 550/G of caprylic acid (cos), 40% of capric acid (Cl) and smaller proportions of caproic and lauric acid and containing 4 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hydroxy group of the mixture of the glyceride polyoxyethylene compounds, were mixed with 75 parts of water. The mixture had a viscosity which was considerably below the value of 5000 cP and was no longer able to be determined accurately with the aforementioned measuring device. The mixture had an inadequate adhesion to damp metal surfaces.

Comparison Example 2.

25 parts of a mixture of 42% of fatty acid monoglyceride polyoxyethvlene compound and 48% of fatty acid, diglyceride polyoxyethvlene compound. derived from a fatty acid mixture obtained from lard and containing 1.9 mole of radicals derived from ethylene oxide per mole of polyoxvethylene-substituted hydroxy group, were dispersed in 75 parts of water. The mixture had a viscosity of 7200 cP. Although the mixture had an adequate adhesion to damp metal surfaces, the lubricant film formed was uneven and tended to be torn away.

Comparison Example 3.

25 parts of a mixture of 42% of fatty acid monoglyceride polyoxyethylene compound and 48% of fatty acid diglyceride polyoxyethylene compound derived from the fatty acid mixture used in Comparison Example 2 and containing 6.25 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hvdroxy group, were mixed with 75 parts of water. The mixture had a viscosity of 4800 P, and formed a thin lubricant film with poor adhesion.

Example 1.

25 parts of a mixture of 42% of fatty acid monoglyceride polyoxyethylene compound and 48% of fatty acid diglyceride polyoxyethylene compound, derived from a fatty acid mixture obtained from lard and containing 4 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hydroxy group, were dispersed in 75 parts water. An opaque emulsion having a viscosity of 13000 cP was obtained. The emulsion displayed excellent adhesion to damp metal surfaces and formed a cohesive stable protective film.

Example 2.

25 parts of a fatty acid polyoxyethylene compound derived from colza oil fatty acid and containing 3 moles of radicals derived from ethylene oxide per mole of fatty acid, were dispersed in 75 parts water. The aqueous dispersion had a viscosity of 6500 cP and displayed both adequate adhesion and film formation behaviour.

Examples 3 to 5.

Mixtures were prepared from the fatty acid polyoxyethylene compound mentioned in Example 2, potassium oleate and water, as follows: Parts of fatty acid polyoxyethylene compound 30 45 40 Parts of potassium oleate 1 1 1 Parts of water 69 64 59 Viscosity cP 15700 16400 28800 Adhesion and film bonding of the mixtures were good.

Examples 6 to 11.

25 parts of a mixture of (a) 48 parts of a mixture of 40% of fatty acid monoglyceride polyoxyethylene compound and 50% of fatty acid diglyceride polyoxyethylene compound, derived from a fatty acid mixture of 27% of palmitic acid, 12% of stearic acid, 48% of oleic acid and 8% of linoleic acid, as well as small proportions of lauric acid, myristic acid an dhigher fatty acids, and having a degree of polyoxyethylene substitution of 4 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hydroxy group, and (b) 52 parts of a fatty acid polyoxyethylene compound derived from a fatty acid mixture of 12% of palmitic acid, 3% of stearic acid, 26% of oleic acid, 18% of linoleic acid, 6% of linolenic acid and 21 /o of erucic acid, as well as small proportions of lauric acid, myristic acid and higher fatty acids, and having a degree of polyoxyethylene substitution of 3 moles of radicals derived from ethylene oxide per mole of fatty acid, were mixed with 75 parts of water.

The emulsion thus obtained had a viscosity of 145000 cP, adhered excellently to damp metal surfaces and formed a cohesive lubricant film.

A 20% dispersion of the mixture had a viscosity of 5900 cP, a 30% dispersion a viscosity of 12000 cP, and a 40% dispersion a viscosity of 22300 cP.

A 23% dispersion of (a) 20 parts of the aforesaid mixture of monoglyceride polyoxyethylene compound and diglyceride polyoxyethylene compound and (b) 80 parts of the aforementioned fatty acid polyoxyethylene compound had a viscosity of 10300 cP. A 23% dispersion of (a) 70 parts of the aforementioned mixture of monoglyceride polyoxyethylene compound and diglyceride polyoxyethylene compound and (b) 30 parts of the aforementioned fatty acid polyoxyetllylene compound had a viscosity of 24500 cP.

Examples 12 to 18.

Mixtures were prepared from (a) a mixture of 36% of fatty acid monoglyceride polyoxyethylene compound and 34% of fatty acid diglyceride polyoxyethylene compound, derived from a fatty acid mixture of 30% of palmitic acid, 13% of stearic acid, 30% of oleic acid and 2% of linoleic acid, as well as small proportions of myristic acid and higher fatty acids, and containing 4 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hydroxy group, and (b) a fatty acid polyoxyethylene compound derived from a fatty acid mixture of 4% of lauric acid, 3% of myristic acid, 19% of palmitic acid, 2% of stearic acid, 31% of oleic acid, 8% of linoleic acid and 23% of erucic acid, as well as small proportions of intermediate fractions and higher fatty acids, and containing 3 moles of radicals derived from ethylene oxide per mole of fatty acid. 25% dispersions of the mixtures had the viscosities given in the following Table.

Mixture % Mixture of mono glyceride polyoxy ethylene compound Viscosity (cP) and diglyceride Fatty acid polyoxyethylene polyoxyethylene Shear gradient Shear gradient compound compound of 2.64 cm~l of 428 cm~l 100 7000 140 20 80 9000 150 40 60 19500 260 50 50 2200n 280 60 40 29000 340 80 20 22300 290 100 0 22500 200 Example 19.

23 parts of a monoester obtained by esterification of 1.1 mole of triethylene glycol having a hydroxy number of 740 with 1 mole of a fatty acid mixture having an acid value of 190 and an iodine number of 113 and obtained from colza oil were mixed with 2 parts potassium oleate and simultaneously heated. The 25% emulsion obtained has a viscosity of 21000 cP. Adhesion and film formation were good.

WHAT WE CLAIM IS:- 1. A lubricant for use in the hot-forming of metals comprising an aqueous emulsion of from 5 to 60% by weight of (a) a mixture of (i) a fatty acid monoglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group and (ii) a fatty acid diglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group, and/or (b) a fatty acid polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of fatty acid; the amount of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

a viscosity of 12000 cP, and a 40% dispersion a viscosity of 22300 cP.

A 23% dispersion of (a) 20 parts of the aforesaid mixture of monoglyceride polyoxyethylene compound and diglyceride polyoxyethylene compound and (b) 80 parts of the aforementioned fatty acid polyoxyethylene compound had a viscosity of 10300 cP. A 23% dispersion of (a) 70 parts of the aforementioned mixture of monoglyceride polyoxyethylene compound and diglyceride polyoxyethylene compound and (b) 30 parts of the aforementioned fatty acid polyoxyetllylene compound had a viscosity of 24500 cP.

Examples 12 to 18.

Mixtures were prepared from (a) a mixture of 36% of fatty acid monoglyceride polyoxyethylene compound and 34% of fatty acid diglyceride polyoxyethylene compound, derived from a fatty acid mixture of 30% of palmitic acid, 13% of stearic acid, 30% of oleic acid and 2% of linoleic acid, as well as small proportions of myristic acid and higher fatty acids, and containing 4 moles of radicals derived from ethylene oxide per mole of polyoxyethylene-substituted hydroxy group, and (b) a fatty acid polyoxyethylene compound derived from a fatty acid mixture of 4% of lauric acid, 3% of myristic acid, 19% of palmitic acid, 2% of stearic acid, 31% of oleic acid, 8% of linoleic acid and 23% of erucic acid, as well as small proportions of intermediate fractions and higher fatty acids, and containing 3 moles of radicals derived from ethylene oxide per mole of fatty acid. 25% dispersions of the mixtures had the viscosities given in the following Table.

Mixture % Mixture of mono glyceride polyoxy ethylene compound Viscosity (cP) and diglyceride Fatty acid polyoxyethylene polyoxyethylene Shear gradient Shear gradient compound compound of 2.64 cm~l of 428 cm~l 100 7000 140 20 80 9000 150 40 60 19500 260 50 50 2200n 280 60 40 29000 340 80 20 22300 290 100 0 22500 200 Example 19.

23 parts of a monoester obtained by esterification of 1.1 mole of triethylene glycol having a hydroxy number of 740 with 1 mole of a fatty acid mixture having an acid value of 190 and an iodine number of 113 and obtained from colza oil were mixed with 2 parts potassium oleate and simultaneously heated. The 25% emulsion obtained has a viscosity of 21000 cP. Adhesion and film formation were good.

WHAT WE CLAIM IS:- 1. A lubricant for use in the hot-forming of metals comprising an aqueous emulsion of from 5 to 60% by weight of (a) a mixture of (i) a fatty acid monoglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group and (ii) a fatty acid diglyceride polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group, and/or (b) a fatty acid polyoxyalkylene compound containing from 2 to 6 moles of radicals derived from alkylene oxide per mole of fatty acid; the amount of

the polyoxyalkylene compound or compounds present in the emulsion, the polyoxyalkylene chain length of the polyoxyalkylene compound or compounds present in the emulsion, the fatty acid chain length of the polyoxyalkylene compound or compounds present in the emulsion and/or the fineness of the emulsion being such that the emulsion has a viscosity of 5,000 to 40,000 cP measured in the manner described herein at a shear gradient of 2.64 cm-1 and at a temperature of 300C.
2. A lubricant as claimed in claim 1, wherein the mixtures of the fatty acid monoglyceride polyoxyalkylene compound and the fatty acid diglyceride polyoxyalkylene compound and/or fatty acid polyoxyalkylene compound is derived from a fatty acid containing from 12 to 22 carbon atoms or from a mixture of such fatty acids.
3. A lubricant as claimed in claim 2, wherein the mixture of the fatty acid monoglyceride polyoxyalkylene compound and the fatty acid diglyceride polyoxyalkylene compound and/or the fatty acid polyoxyalkylene compound is derived from a fatty acid mixture of preponderant proportion of which mixture consists of fatty acids containing from 16 to 22 carbon atoms.
4. A lubricant as claimed in any of claims 1 to 3, wherein the mixture of the fatty acid monoglyceride polyoxyalkylene compound and the fatty acid diglyceride po]yoxyalkylene compound contains from 3 to 5 moles of radicals derived from alkylene oxide per mole of polyoxyalkylene-substituted hydroxy group.
5. A lubricant as claimed in any of claims 1 to 4, wherein the fatty acid polyoxyalkylene compound contains from 2.5 to 4 moles of radicals derived from alkylene oxide per mole of fatty acid.
6. A lubricant as claimed in any of claims 1 to 5, wherein the emulsion contains from 10 to 40% by weight of the mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyalkylene compound and/or of the fatty acid polyoxyalkylene compound.
7. A lubricant as claimed in any of claims 1 to 6, wherein the emulsion addi tionally contains a sodium or potassium salt of a fatty acid having from 12 to 22 carbon atoms.
8. A lubricant as claimed in any of claims 1 to 7 wherein the alkylene oxide is ethylene oxide.
9. A lubricant as claimed in any of claims 1 to 8, the amount o fthe polyoxyalkylene compound or compound present in the emulsion, the polyoxyalkylene chain length of the polyoxyalkylene compound or compounds present in the emulsion, the fatty acid chain length of the polyoxyalkylene compound or compounds present in the emulsion and/or the fineness of the emulsion being such that the emulsion has a viscosity of 10,000 to 30,000 cP measured in the manner described herein at a shear gradient of 2.64 cm 1 and at a temperature of 30 C.
10. A lubricant substantially as described in any of the foregoing Examples 1 to 19.
11. A method of hot-forming metal, wherein the hot-forming is carried Out in the presence of a lubricant as claimed in any of claims 1 to 10.
12. Metal which has been hot-formed by the method claimed in claim 11.