GB2054640A

GB2054640A - Hot-forming of metals lubricant

Info

Publication number: GB2054640A
Application number: GB8018451A
Authority: GB
Original assignee: Dynamit Nobel AG
Current assignee: Dynamit Nobel AG
Priority date: 1979-06-30
Filing date: 1980-06-05
Publication date: 1981-02-18
Also published as: FR2460320A2; DE2926513A1; JPS5610595A; LU82565A1; IT8049103A0; IT1145269B; GB2054640B; BE883973R; NL8003746A

Abstract

Patent Application No. 54205/77 claims 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 polyoxyalklene compound containing from 2 to 6 moles or 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 aqueous emulsion being such that it has a viscosity of 5,000 to 40,000 cP measured by the use of a particular rotational viscosimeter at a shear gradient of 2.64 cm<-1> and at a temperature of 30 DEG C. This lubricant is modified in accordance with the present invention in that the emulsion additionally contains a fatty acid ester of a polyol containing from 2 to 6 methylol groups bonded to quaternary carbon atoms in an amount of up to five times the amount of component (a) and/or component (b). The modified lubricant, when it becomes diluted with cooling water, is easier to separate from such water.

Description

SPECIFICATION Lubricant for use in the hot-forming of metals This invention relates to a modification of the lubricant, for the hot-forming of metals, according to British Patent Application No. 54205/77 (German Offenlegungsschrift No. 2,700,040). The modification according to the present invention enables the lubricant to be better adapted to the various conditions arising from the various forming techniques used, from the different machines used in one and the same processing operation and from the auxiliary systems involved in the actual forming process.

For example, it has been found that, although lubricants in accordance with British Patent Application No. 54205/77 (German Offenlegungsschift No. 2,700,040) are useful in many cases, i.e. they provide an adequate lubricating or separating effect between the tools used and the materials to be formed, the high emulsion stability of these lubricants gives rise to difficulties when it comes to re-using the spent emulsion, which may possibly be diluted with cooling water. These difficulties are attributable to the fact that the stability of the emulsion itself and of the heavily diluted emulsion which is obtained when the tools are cooled with large quantities of cooling water is so great that, in those occasional cases where it is intended to reuse the waste water obtained by the forming process, it is difficult to separate off the lubricant residues present.In such cases it is desirable for the lubricant to be modified such that the constituents of the lubricant may readily be separated from the waste water whilst, at the same time, the lubricating and separating effect and the other advantages mentioned in British Patent Application No. 54205/77 (German Offenlegungsschrift No. 2,700,040) are retained or improved .

According to the present invention, this is achieved by a lubricant according to British Patent Application No. 54205/77 (German Offenlegungsschrift No. 2,700,040), which lubricant also contains fatty acid esters of polyols containing from 2 to 6 methylol groups in the molecule, the methylol groups being bound to quaternary carbon atoms, in a quantity of up to five times the content of (a) the mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalklene compound, and/or (b) the fatty acid polyoxyalkylene compound.

Thus, according to the present invention, there is provided a lubricant for use in the hotforming 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 mole of polyoxyalkylene-substituted hydroxy group, and/or (b) a fatty acid polyoxyalkylene compound containing from 2 to 6 mole of fatty acid; the aqueous emulsion additionally containing a fatty acid ester of a polyol containing from 2 to 6 methylol groups bonded to quaternary carbon atoms in an amount of up to five times the amount of (a) the mixture of the fatty acid monoglyceride polyoxyalklene compound and the fatty acid diglyceride polyoxyalkylene compound, and/or (b) the fatty acid polyoxyalkylene compound; and 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, the fineness of the emulsion, the amount of the fatty acid ester of a polyol present in the emulsion, the fatty acid chain length of the fatty acid ester of a polyol, and/or the chain length of the polyol being such that the emulsion has a viscosity of 5000 to 40,000 cP measured in the manner described herein at a shear gradient of 2.64 cm-' and at a temperature of 30 C.

The quantity of active ingredients in the lubricant, i.e. the polyoxyalkylene compounds of the fatty acid partial glycerides and/or of the fatty acids and the polyol esters, preferably does not exceed from 5 to 60% by weight of the mixture as a whole.

The fatty acid esters of polyols containing from 2 to 6 methylol groups bound to a quaternary carbon atom can also be described as fatty acid polyesters because several fatty acid residues are present in the molecule and are bound to the methylol groups. The polyols containing from 2 to 6 methylol groups on one or more quaternary carbon atoms have a branched molecule structure with at least 5 carbon atoms, especially since condensation products of two or more such polyols, such as diphentaerythritol or tripentaerythritol, which are partly formed during production of the polyols, may also be present. Preferred polyols are neopentyl glycol, trimethylol propane, pentaerythritol and dipentaerythritol. The methylol groups are completely or largely esterified with fatty acids, the latter case being preferred.In other words, the products in question are polyol esters the methylol groups of which are in the main provided with fatty acid residues and, to a lesser extent, contain free methylol groups. In the main is understood to mean that the degree of esterification should be so high that the ester has a low hydroxyl number. It is preferred to use complete polyol esters which have a hydroxyl number of less than 50 as a result of not quite complete esterification with fatty acids.

The fatty acid component of the polyol esters may be substantially the same fatty acids as are present in the fatty acid monoglyceride polyoxyalkylene compounds, the fatty acid diglyceride polyoxyalkylene compounds or the fatty acid polyoxyalkylene compounds, e.g fatty acids containing from 12 to 22 carbon atoms (for example lauric acid, myristic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid and erucic acid) or mixtures of these fatty acids, preferably mixtures of fatty acids containing from 16 to 22 carbon atoms. It is of particular advantage to use fatty acid mixtures based on natural raw materials, for example palm oil, peanut oil, cottonseed oil, soya bean oil, sunflower oil, rapeseed oil, lard, beef tallow, whale oil and herring oil.

The fatty acid mixtures on which the fatty acid monoglyceride polyoxyalkylene compounds, the fatty acid diglyceride polyoxyalklene compounds, the fatty acid polyoxyalkylene compounds and/or the fatty acid polyol esters are based may be the same of different. For example, a mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxyalkylene compound based on lard may readily be combined with a fatty acid polyol ester based on peanut oil. Any conceivable combination of fatty acid mixtures is possible both for the mixture of fatty acid monoglyceride polyoxyalkylene compound and fatty acid diglyceride polyoxylene compound and/or the fatty acid polyoxyalkylene compound and for the fatty acid polyol ester with the sole proviso that the fatty acid or mixture of fatty acids used preferably has a chain length of from 12 to 22 carbon atoms.For economic reasons, however, the same fatty acid or fatty acid mixture will generally be used both for the polyoxyalkylene component and for the polyol ester component.

The lubricant according to the invention may be prepared by stirring the polyoxyalkylene component and the polyol ester component into water. Since the emulsion is spontaneously formed, dispersion of the products in the aqueous phase does not require any further measures, such as homogenisation for example.

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 15,000 to 30,000 cP, measured under the specified conditions. All viscosity measurements herein, including those of the Examples hereinbelow, were made on the rotational viscosimeter "Rotovisko" made by Gebruder Haake KG and were measured at a shear gradient of 2.64cm~' 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 used in combination with the measuring element 500 which, due to its special shape is particularly suitable for testing emulsions. Details may be obtained fron the trade pamphlet "Rotovisko, Beschreibung und Gebrauchsanleitung", Druckschrift 105/lob, and from the article by W. Heinz in "Rheologie und Rheometrie mit Rotationsviskosimetern'' 2nd ed.

Springer-Verlag, Berlin.

Lubricants having viscosities below 5000 cP and above 40,000 cP, even if they contain polyoxyalkylene components and polyol ester components the same or similar in composition to those used according to the invention, are not suitable for use according to the invention.

Lubricants having viscosities below 5000 cP show inadequate adhesion to moist metal surfaces and, accordingly, are unsuitable for use in practice. On the other hand, the viscosity range of the lubricant according to the invention is limited at its upper end by the need to convey and apply the aqueous dispersion or emulsion by the usual means such as, for example, pumps and nozzles. In addition, viscosities above 40,000 cP are undesirable because difficulties are encountered in uniformly applying the lubricating film.

It has been found that any increase in the amount of the polyol esters used according to the invention produces a reduction in the viscosity of the emulsion. However, emulsions such as these may readily be used for the intended purpose provided that their viscosities lie within the range of from 5000 to 40,000 cP, preferably from 15,000 to 30,000 cP.On the other hand, it is additionally possible by utilising this effect to modify emulsions of the type which, with viscosity values of the order of 40,000 cP, still just have a value in the range according to the invention and, accordingly, are suitable for use as lubricants according to the invention, but on account of their high viscosity necessitate a greater outlay on apparatus for transport through pipe systems and for spraying, or even of the type which would have a viscosity in excess of 40,000 cP, by the addition of small quantities of polyol esters in such a way that the viscosity values are correspondingly reduced and may be brought for example into the preferred range of from 15,000 to 30,000 cP.

It has also been found that lubricants of the type which, particularly with high contents of the polyol esters, would have an inadequate viscosity, for example less than 5000 cP, and as a result could no longer be used due to inadequate adhesion to moist metal surfaces, may also be converted into a lubricant according to the invention having adequate viscosity and good adhesion by the addition of small quantities of thickeners, for example cellulose ethers, alginates, carragenates, polyacrylates, and inorganic thickeners. Examples of inorganic thickeners are bentonites and highly dispersed silica. It is preferred to use cellulose ethers, particularly methyl celluloses. It is particularly preferred to use a combination of methyl hydroxy ethyl celluloses of the highly etherified type with methyl celluloses of the same type.In this case, the methyl hydroxy ethyl cellulose (it is of particular advantage to use a type having a high viscosity because in that case only minimal quantities need be added) is used for roughly adjusting the viscosity, whereas through the simultaneous use of a methyl cellulose having a low viscosity so much thickening material can be introduced that the necessary adhesion and a good filmforming capacity are obtained. All viscosities within the range according to the invention may be attained without difficulty by suitably selecting the concentrations of the polyol esters, i.e. the cellulose ethers. Other ways of adjusting the viscosity are disclosed in British Patent Application No. 54205/77 (German Offenlegungsschrift No. 2,700,040).

The quantity in which the thickener is used should not exceed 5% by weight, based on the final emulsion. Quantities of from 0.01 to 3.5% by weight are preferred.

It has also been found that it can be of advantage to use extreme pressure additives (hereinafter abbreviated to "EP additives") for particularly difficult lubrication and separation problems. In forming operations involving high relative speeds between tool and workpiece, particularly pronounced wear zones are frequently formed because any break in the lubricating film results in cold welding in these zones. In cases such as these, it is possible, by using EP additives which produce a pressure-resistant lubricating film, for example by chemical reaction with the metal, to obtain an additional lubricating effect by which the degree of wear can be considerably reduced.It is preferred to use EP additives of the long-chain phosphoric acid ester type, which are available for example under the trade name "Gafen" (a product of GAF, Germany), and/or sulphur compounds, particularly of the polysulphide type (for example di-# nonyl polysulphide and di-t-dodecyl polysulphide), which are known as high-pressure additives for drilling oils. Others EP additives are, for example, chloroparaffins, thiophosphoric acid esters and sulphurised or sulphur-chlorinated sperm oil. The principles mentioned in connection with the additional use of the fatty acid polyol esters also apply to the incorporation of the EP additives. In addition, the viscosity of the lubricant is also reduced by the EP additives, so that the described cellulose ethers may have to be used for adjusting the viscosity.The EP additives may be present in the final emulsion in quantities of from 0.01 to 10% by weight and preferably in quantities of from 0.1 to 6.0% by weight.

The lubricant according to the invention shows excellent and improved adhesion to moist metal surfaces and, accordingly, although dispersible or emulsifiable in water, may be spread onto water-cooled rollers to form a particularly uniform lubricating film.

Any residues of lubricant which may have been deposited during application, for example by spraying, on the roll stands and fittings in industrial use may be completely removed without difficulty, for example by flushing with a powerful jet of water.

One particular advantage of lubricants containing fatty acid polyesters, particularly large amounts of fatty acid polyol esters, is that the lubricant-containing effluents may be very largely freed from lubricant residues without difficulty, for example by clarification in settling tanks, filtration through gravel filters and similar measures, and may then be re-used, for example as cooling water. Another advantage is that the emulsion, which remains very stable during its use as a lubricant, may be rapidly degraded during treatment of the effluents and the degradability attributable to the composition of the lubricants is not impeded by their remaining in emulsified form.

The lubricant according to the invention is preferably used in the hot rolling of steel profiles where it forms a uniform lubricating film and shows good adhesion to the rolls combined with an adequate lubricating and separating effect.

The preferred features of the lubricant described in British Patent Application No. 54205/77 (German Offenlegungsschrift No. 2,700,040) are also applicable to the lubricant of the present invention.

The following Examples illustrate the invention.

EXAMPLES 1 to 19 An active component system consisting of 20% by weight of a fatty acid polyoxyethylene compound (derived from rapeseed oil fatty acid containing approximately 20% of erucic acid) containing 3 moles of radicals derived from ethylene oxide per mole of fatty acid (which polyoxyethylene compound is hereinafter abbreviated as "FAPC") and 80% be weight of a trimethylol propane ester based on the same fatty acid and having a hydroxyl number of 30 (which ester is hereinafter abbreviated as "TMPE") was used in Examples 1 to 8. In Examples 9 to 11, the proportions of FAPC to TMPE were 20% and, in Examples 12 to 19, 22%. The active component systems were processed to form emulsions having a total content of lubrication-active ingredients of 25% by weight. The viscosities of the lubricants are given in the following Table 1.

TABLE 1 EP additive Cellulose ether FAPC/ TMPE MC MHEC Viscosity Example (%) (%) type (%) (%) (cP) 1 22.5 2.5 LM 400 - 1.0 7800 2 22.5 2.5 LM 400 1.1 - 5500 3 22.5 2.5 LM 400 1.3 - 7200 4 22.5 2.5 LM 400 1.6 - 9100 5 22.5 2.5 LM 400 1.8 - 14800 6 22.5 2.5 LM 400 2.0 - 22250 7 22.5 2.5 LB 400 1 0.2 5800 8 22.5 2.5 LB 400 1.25 0.38 9200 9 20 5 LB 400 1 - 6500 10 20 5 LB 400 1 0.1 7800 11 20 5 LB 400 1 0.3 12400 12 22 3 TNPS 2 - 6550 13 22 3 TNPS 0.8 0.6 5890 14 22 3 TNPS 0.8 0.8 12450 15 22 3 TNPS 0.8 1 19650 16 22 3 TNPS 1 0.6 9170 17 22 3 TNPS 1 0.8 15730 18 22 3 TNPS 1.5 0.5 14420 19 22 3 TNPS 2 0.5 24900 In the above Table, MC, means highly etherified methyl cellulose having a viscosity of 1500 cP; MHEC means highly etherified methyl hydroxy ethyl cellulose having a viscosity of 30,000 cP;LM means a long-chain phosphoric acid ester (Gafen LM 400), partially rieutralised with triethanolamine; LB means a long-chain phosphoric acid ester containing free acid (Gafen LB 400); and TNPS means di-t-nonyl polysulphide (made by Societe Nationale des Petroles d'Aquitaine).

EXAMPLES 20 to 24 The lubricants given in the following Table 2 (wherein the abbreviations "FAPC", "TMPE", "MC", "MHEC" and "TNPS" have the meanings given in Examples 1 to 19)were prepared.

TABLE 2 EP Additive Cellulose Ether FAPC TMPE MC HEC Water Viscosity Example (parts) (parts) (parts) (type) (parts) (parts) (parts) (cP) 20 20 20 3 TNPS 0.65 0.20 57 10480 21 25 25 3 TNPS 0.65 0.20 47 24900 22 24 6 3 TNPS 1.7 0.30 67 38000 23 32 8 3 TNPS 1.0 0.50 57 7860 24 40 10 3 TNPS 1.0 0.50 47 27500 EXAMPLES 25 to 31 The following products C, D and E were prepared from fatty acid mixtures A and B having the compositions given in Table 3, below: : Product C = a mixture of fatty acid monoglyceride polyoxyethylene compound and fatty acid diglyceride polyoxyethylene compound derived from fatty acid A and from a mixture of 42% of monoglyceride and 49% of diglyceride before polyoxyethylene substitution, and containing 4 moles of radicals derived from ethylene oxide per mole of hydroxyl group; Product D = a fatty acid polyoxyethylene compound derived from fatty acid mixture B and containing 3 moles of radicals derived from ethylene oxide; Product E = a trimethylol propane ester derived from fatty acid mixture B and having a hydroxyl number of 25.

TABLE 3 Fatty acid mixture A Fatty acid mixture B Palmitic acid 29% 10% Stearic acid 12% 4% Oleic acid 49% 30% Linoleic acid 6% 20% Linolenic acid 1% 5% Erucic acid - 19% Remainder Further fatty acids containing from 12 to 22 carbon atoms The lubricants given in the following Table 4 (wherein the abbreviation "TNPS" has the meaning given in Examples 1 to 1 9) were prepared from products C, D and E.

TABLE 4 Product Product Product EP Additive C D E ---#---------- Water Viscosity Example (parts) (parts) (parts) (parts) (type) (parts) (cP) 25 12 12 9 0 - 67 20970 26 10.5 10.5 9 3 TNPS 67 10480 27 12.5 12.5 10.5 3 TNPS 61.5 24900 28 14 14 12 3 TNPS 57 27520 29 12 12 16 3 TNPS 57 20970 30 24 - 6 3 TNPS 67 10800 31 24 - 16 3 TNPS 57 6500 EXAMPLE 32 Example 21 was repeated with the differences that the fatty acid polyoxyalkylene compound was neopentyl glycol esterified with C16 to C20 fatty acids up to a hydroxyl number of 10 and containing 4 moles of radicals derived from ethylene oxide, and that the propane ester was similarly esterified pentaerythritol. The viscosity of the lubricant was of the order of 25,000 cP.

Claims

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 aqueous emulsion additionally containing a fatty acid ester of a polyol containing from 2 to 6 methylol groups bonded to quaternary carbon atoms in an amount of up to five times the amount of (a) the mixture of the fatty acid monoglyceride polyoxyalkylene compound and the fatty acid diglyceride polyoxyalkylene compound, and/or (b) the fatty acid polyoxyalkylene compound; and 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, the fineness of the emulsion, the amount of the fatty acid ester of a polyol present in the emulsion, the fatty acid length of the fatty acid ester of a polyol, and/or the chain length of the polyol being such that the emulsion has a viscosity of 5000 to 40,000 cP measured in the manner described herein at a shear gradient of 2.64 cm-' and at a temperature of 30 C.

2. A lubricant as claimed in claim 1, wherein the mixture of the fatty acid monoglyceride polyoxyalkylene compound and the fatty acid diglyceride polyoxyalkylene compound and/or the fatty acid polyoxyalkylene compound and/or the fatty acid ester of a polyol 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 and/or the fatty acid ester of a polyol is derived from a fatty acid mixture a 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 polyoxyalkylene compound contains from 3 to 5 moles of radicals derivced from alkylene oxide per mole of polyoxyalkylene-su bstituted hyd roxy 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 and/or of the fatty ester of a polyol.

7. A lubricant as claimed in any of claims 1 to 6, wherein the emulsion additionally 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, wherein 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, the fineness of the emulsion, the amount of the fatty acid ester of a polyol present in the emulsion, the fatty acid chain length of the fatty acid ester of a polyol, and/or the chain length of the polyol being such that the emulsion has a viscosity of 15,000 to 30,000 cP measured in the manner described herein at a shear gradient of 2.64 cm-' and at a temperature of 30 C.

10. A lubricant as claimed in any of claims 1 to 9, wherein the emulsion additionally contains a thickening agent in an amount of up to 5% by weight.

11. A lubricant as claimed in claim 10, wherein the thickening agent is of the highly etherified methyl cellulose type and/or of the highly etherified methyl hydroxy ethyl cellulose type.

12. A lubricant as claimed in any of claims 1 to 10, wherein the emulsion additionally contains an extreme pressure additive in an amount of up to 10% by weight.

13. A lubricant as claimed in claim 12, wherein the extreme pressure additive is of the longchain phosphoric ester type and/or of the polysulphide type.

14. A lubricant substantially as described in any of the foregoing Examples.

15. A method of hot-forming metal, wherein the hot-forming is carried out in the present of a lubricant as claimed in any of claims 1 to 14.

16. Metal which has been hot-formed by the method claimed in claim 15.