CS195348B2 - Lubricants for thermal treatment of metals - Google Patents

Description

The present invention relates to a lubricant system for hot metal forming. In particular, the present invention relates to a non-environmentally friendly water-containing lubricant system which is suitable for metal-free metal cutting, such as rolling or drawing, and which guarantees sufficient lubrication or separation between the tool used and the molded material.

The known lubricant systems, for example based on tar or mineral oils, have considerable disadvantages. With the existing water cooling of tools - in the case of rolling machines with a high water consumption - cracking products are obtained and the non-decomposed proportions of mineral oil remain in the cooling water circuit. The separation of biodegradable substances, which in an unthinkable way burden the waste water, leads to a substantial price increase and limits the economy of production.

Products containing tar and mineral oils decompose by heat due to the high temperature of the workpiece to form dense smoke and soot flakes, which need to be removed on the basis of occupational hygiene, which also entails substantial investment costs.

After a short period of operation, the lubricant residues cover the fitting and structure in the form of a thin film, which can only be removed with difficulty. Oil-coated, smooth objects can interfere with operation and cause accidents by slipping or slipping.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a lubricant for hot metal forming, in particular for hot-rolling steel, which avoids the disadvantages of known mineral oil-based lubricants, which further allows the application of conventional fittings, pumps, nozzles and the like. which would cause good film formation on the tools used and which would have excellent adhesion upon application to the wet metal surface and 1 after the tools were cooled with running water.

This object has been achieved by a lubricant system comprising an aqueous dispersion or emulsion containing 5 to 60% by weight of fatty acid monodiglyceride ethoxylates and / or fatty acid ethoxylates, wherein the monodiglyceride ethoxylates contain 2 to 6 moles, preferably 3 to 6 moles. up to 5 moles, alkylene oxide per mole of hydroxyl groups present and fatty acid ethoxylates contain 2 to 6 moles, preferably 2.5 to 4 moles, alkylene oxide per mole of fatty acid ethoxylates, and the aqueous dispersion, e.g. in the range of 5000 to 40,000 cP at a shear gradient of 2.64 cm @ ¹ and a temperature of 30 ° C.

By ethoxylates is meant reaction products preferably with ethylene oxide or optionally propylene oxide.

Fatty acid ethoxylates and fatty acid partial glyceride ethoxylates are known and can be prepared by the direct reaction of fatty acids or partial fatty acid glycerides with ethylene oxide or propylene oxide, thereby incorporating predominantly unilaterally alkoxy chains linked to the hydroxyl groups of the fatty acids or partial glycerides. are terminated with a hydrogen atom.

Preference is given to mixtures of fatty acid monodiglyceride ethoxylates with fatty acid ethoxylates, in particular those which contain at least 10, but usually at least 20, percent by weight of one of the two components; however, mixtures of individual fatty acid monodiglyceride ethoxylates or, optionally, individual fatty acid ethoxylates with each other are also possible.

By monodiglycerides is meant mixtures which are free of triglycerides or are lowered in triglycerides and whose content of mono- and diglycerides does not generally deviate from 30 to 100% by weight, preferably 55 to 90% by weight. The fatty acid residues of the partial glycerides or the free fatty acids may be saturated or unsaturated; hydroxylated fatty acid residues should not be included.

Although lubricating agents containing fatty acid ethoxylates in DOS 2 -446 319 have been proposed, water-soluble lubricants have been prepared here for other uses, which form water-soluble true transparent or semi-transparent solutions.

The lubricating agents of DOS 2,446,319 are disadvantageous because of their low viscosity and thus low adhesion to the tool. From tools cooled by running water, these lubricants are washed off and are therefore unsuitable for their lubrication.

Another disadvantage of the lubricant compositions of DOS 2,446,519 is the complex preparation of three - components, namely (A) a substance with a long alkoxy chain - water soluble, (B) a substance with a shorter alkoxy chain soluble in oil and (C) surface active substance.

Thus, the environment of the present invention cannot be solved according to DOS 2,446,319.

The suspensions according to the invention preferably contains 10 to 40 ^iO / o by weight ethoxylates, with increasing content - increased viscosity and ethoxylates ta.lf - there is a possibility of any adjustment of the viscosity. The second way of adjusting the viscosity lies in the length of the alkoxy chains, and in many cases longer alkoxy chains lower the viscosity.

However, the degree of dispersion of ethoxylates in the aqueous phase of the dispersion or emulsion, the chain length of the fatty acids and the content of monoglycerides or diglycerides in the partial glycerides also have a further effect on viscosity, so that the viscosity of the aqueous dispersion is not due to chemical analysis of certain ethoxylation products acids with sufficient accuracy to predict.

it should be assumed, therefore, that the desired viscosity of a particular product is adjusted to the viscosity required for a particular application by simply mixing high viscosity dispersions and low viscosity dispersions after optionally measuring the viscosity of the starting components.

The preferred ethoxylation step is between 3 and 5 moles of ethylene oxide per hydroxyl group of the partial glycerides for monodiglyceride ethoxylate of fatty acids and between 2.5 and 4 moles of ethylene oxide per mole of fatty acid.

Dispersions or emulsions have the considerable advantage that they form spontaneously. It has been found that aqueous dispersions or emulsions of monodiglyceride ethoxylates of fatty acids with a sethoxylation degree of less than 2 moles of ethylene oxide per mole of hydroxyl groups present and / or fatty acid ethoxylates with an ethoxylation degree of less than 2 moles of ethylene oxide per mole of fatty acid - adhesion, on a wet metal surface, such as the surface of water-cooled rollers, but the formation of a uniform lubricating film is not sufficient. In particularly smooth or highly water-sprayed areas, the film breaks, resulting in increased tool wear.

Aqueous dispersions or emulsions with fatty acid monodiglyceride ethoxylate and / or fatty acid ethoxylates having an ethoxylation degree higher than 6 moles of ethylene oxide per mole of hydroxyl groups or one mole of a fatty acid having a poor adhesion to the wet metal surface possible safe application of the lubricating film, for example by spraying onto rotating, water-sprayed rollers, since the lubricating film is washed off quickly.

It has further been found that the lubricant system of the present invention must have a viscosity in the range of 5000 to 40,000 cP, preferably in the range of 15,000 to 30,000 cP, measured under the stated conditions.

The necessary viscosity measurements are performed on a Rotovisko rotary viscometer. The MV II P tempered Coulet apparatus is used in combination with the measuring head 500, which, due to its special shape, is suitable for the examination of dispersions or emulsions. Details are described in the company's "Rotary Rotor, Description and Instruction Manual", copy 105/16, as well as in W. Heinz, Rheologie und Rheometrie mlt Rotationsviskosime195348 tern, 2nd edition, publ. Sprtnger, Berlin.

The above range of viscosities are obtained at a shearing gradient of ¹ and 2.64 cm at 30 ° C. Lubricant compositions with viscosities below 5000 and above 40,000 cP, even though they contain ethoxylates of the corresponding substances or substances of a similar composition to those of the present invention, are not suitable to solve the task.

Lubricants with a viscosity below 5000 cP show insufficient adhesion to the wet metal surface and are therefore not applicable in practice. The upper limit of the viscosity range of the lubricant system of the present invention, on the other hand, is that the transport and application of the aqueous dispersions or emulsions must be ensured by conventional operating devices such as pumps, nozzles and the like. In addition, viscosities of over 40,000 cP are also undesirable because of the difficulty of uniform film deposition.

Furthermore, the lubricant system of the present invention exhibits so-called plastic viscosity behavior. This is associated with the existence of a fluidity limit which exceeds 50 dyn.cm ² (obtained by the stress relieving method after 30 s). In connection with this behavior, a decrease in viscosity is observed with increasing shear gradient. Thus, a viscosity value in the range of 100 to 500 cP was obtained for the lubricant system of the present invention at a shear gradient of 428 cmi and a temperature of 30 ° C.

The viscosity adjustment within the range of the present invention can be made by varying the concentration of fatty acid monodiglycerethoxylates and / or fatty ethoxylates. of acids. Thus, dispersions or emulsions having a higher ethoxylate content generally have a higher viscosity and vice versa. The desired viscosity of the aqueous dispersions or emulsions can, however, also be adapted by mixing, for example, two ethoxylated products, one of which is used as a single component in the corresponding dispersion or emulsion, gives a low viscosity and the other used as a single component gives a viscosity high.

The fatty acid residues of the ethoxylates of the present invention are derived from C12-22 fatty acids, such as lauric acid, myristic acid, palmitic acid, stearic acid, palmitoolic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, erucic acid or mixtures of these acids, preferably mixtures of fatty acids having 16 to 22 carbon atoms. ,

The ethoxylates may be particularly advantageously prepared on the basis of natural raw materials such as palm oil, peanut oil, cottonseed oil, soybean oil, sunflower oil, linseed oil, rapeseed oil, lard, beef tallow, whale fat, fish oil and the like. Fatty acid monodiglyceride ethoxylates can be prepared by known methods, for example, by esterifying the abovementioned fats or oils with glycerol, or by esterifying the fatty acids obtained by digesting the fats with glycerin and then ethoxylating with a given amount of ethylene oxide. Fatty acid ethoxylates can be prepared by treating ethylene oxide with fatty acids obtained by breaking down fats or by esterifying fatty acids with polyethylene glycol of an appropriate chain length.

The lubricant system of the present invention is prepared by admixing fatty acid mono-glyceride ethoxylates and / or fatty acid ethoxylates in water. The dispersion or emulsion is formed spontaneously, further measures, such as homogenization, can be dispensed with after dispersing the ethoxylates in the aqueous phase. The aqueous dispersions or emulsions thus obtained can be used immediately after manufacture, but they can also be well stored because they exhibit good stability and remain essentially unchanged for a long period of time, for example several weeks. In the latter case, it is expedient to avoid by addition of conventional tonicity agents, the microbial decomposition is reduced. In addition, other additives, such as corrosion protection agents, vapor phase inhibitors, antloxidants and the like, can also be added to the lubricating compositions in minor amounts.

If fatty acid ethoxylates are used without the addition of monodiglyceride ethoxylates, it is expedient to add a small amount of the sodium or potassium salt of the C 12 -C 22 fatty acid in the preparation of the corresponding dispersion or emulsion. This facilitates the formation of a dispersion or emulsion and the application of the lubricating film is more even.

The lubricant system of the present invention meets the requirements that have to be determined based on environmental protection to an increasing extent for the use of excipients in industrial fields. Thus, by using the 25% dispersion or emulsion of the present invention alone, it is possible to achieve a one-fourth reduction in organic material compared to mineral oil-based lubrication systems.

The lubricant system of the present invention is well biodegradable, so that residues which remain in the wastewater cause only a slight load. For example, in hot-rolling steel, when an equally larger portion of the organic material burns out when the water evaporates at the exit of the rolling gap, the remaining proportions are completely negligible. By using the lubricant system of the present invention, a substantial reduction in the formation of fume and soot is achieved compared to the behavior of the mineral oil-containing substances. The odor that occurs when mineral oil systems are used due to the formation of disgusting smell crackers.

The products of the invention are not observed when using the lubricant system according to the invention.

Lubrication system according to. The present invention exhibits excellent adhesion to the wet metal surface and therefore can be applied to water-cooled rollers, although it is dispersible or possibly emulsifiable in water, forming a uniform lubricating film. On the other hand, there are lubricant residues that may be present, for example. . spraying, precipitation on the rolling mill and fittings, without problems and completely eliminated, for example, by spraying with a strong stream of water.

Advantageous use of the lubricant system according to. The present invention is found in hot rolling of steel profiles. This results in an even formation of the lubricating layer, good adhesion to the rollers and an excellent lubricating and separating effect.

In the following examples, the lubricant system of the present invention is described in more detail. Percentages are by weight unless otherwise stated.

The term OHC refers to the hydroxyl number, the KC acid number and the JC color number of the iodine solution. The latter expresses the degree of double bonds, the determination of which is carried out in accordance with the DGF-Einheitsmethoden (Deutsche Gesellschaft fur Fettwissenschaft), part D-IV 2b (61) or C-IV. . 4a (52).

Example 1 (comparative). parts of fatty acid monodiglyceride ethoxylate (from partial glycerides with 46% monoglyceride and 50% diglyceride) based on% caprylic acid (Ca)% caprile acid as well as a minor proportion of caproic acid and lauric acid with 4 moles of ethylene oxide per mole of hydroxyl groups mixtures of partial glycerides, mixed with 75 parts of water. This mixture has a viscosity which is substantially below 5000 cP and cannot be determined precisely by the above-described metering arrangement. The mixture exhibits insufficient adhesion to the wet metal surface.

Example 2 (comparative) parts of fatty acid monodiglyceride ethoxylate (42% monoglyceride and 48% diglyceride) based on a mixture of fatty acids obtained from lard with 1.9 moles of ethylene oxide per mole of hydroxyl groups present are dispersed in 75 parts of water. The mixture has a viscosity of 7200 cP, measured at a shear gradient of 2.64 cm ^-1 and a temperature of 30 ° C. While the investigation has achieved excellent - adhesion to the wet metal surface, the applied lubricating film is uneven and tends to tear.

Example 3 (comparative) parts of fatty acid monodiglyceride ethoxylate (42% monoglyceride and 48% diglyceride), as in Example 2, with 6.25 moles of ethylene oxide per mole? hydroxyl groups are mixed with 75 parts of water. The mixture has a viscosity of - 4,800 cP, measured under the above conditions, and yields a thin, very poorly adhering lubricating film.

Example 4 parts of fatty acid monodeglyceride ethoxylates (42% monoglycerides and - 48% diglycerides) based on a mixture of fatty acids obtained from lard, with 4 moles of ethylene oxide per mole of hydroxyl groups, are dispersed with 75 parts of water. An emulsion with a viscosity of 13,000 cP is obtained. This emulsion exhibits excellent adhesion to the wet metal surface and forms a continuous, stable protective film.

EXAMPLE 5 parts of fatty acid ethoxylates based on rapeseed oil with 3 moles of ethylene oxide per mole of fatty acid are dispersed in 75 parts of water. The aqueous dispersion has a viscosity of 6500 cP and exhibits both excellent adhesion and good film formation.

Example 1 a d 6 to 8

Mixtures were prepared from the ethoxylates of Example 5, potassium oleate and water. In this case, mixtures having the following viscosity are obtained.

parts of fatty acid ethoxylates 30 35 40 parts of potassium oleate 1 1 1 parts of water 69 64 59 viscosity cP 15 700 16 400 28 800

Adhesion and film formation is very good for all mixtures.

Examples 9 to 14 ччириеярк. - parts of the mixture consisting

a) 48 parts of fatty acid monodiglyceride ethoxylates (40% monoglycerides and 50% diglycerides) based on a mixture of fatty acids of palmitic acid% stearic acid

19 * 5 3 4'8% oleic acid ₍ % of linoleic acid I 'of minor proportions of lauric acid, myristic acid and higher fatty acids, with an ethoxylation degree of -4 moles of ethylene oxide per mole of hydroxyl groups - and

(b) 52 parts of fatty acid ethoxylates based on a mixture of fatty acids of palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, erucic acid, minor proportions of lauric acid, myristic acid and higher fatty acids;

25% dispersion from α (dílů) - 70 parts of said monodiglyceride ^; b-xylates a

b) 30 parts of said fatty acid ethoxylates have a viscosity of 24,500 cP.

Examples 15 to 21

From - monodiglyceride ethoxylates (36 ° / o - monoglycerides - and -54% diglycerides). Based on a mixture of fatty acids "of palmitic acid% - stearic acid% oleic acid% -linic acid and a low proportion of myristic acid and higher fatty acids with with an ethoxylation step of 3 moles of ethylene oxide per mole of fatty acid, 75 parts of water are mixed. The emulsion thus obtained has a viscosity of 14,500 cP, adheres perfectly to the wet metal surface and forms a continuous lubricating film.

20% - dispersion of the same mixture of fatty acid monodiglyceride ethoxylates and fatty acid ethoxylates ”has a viscosity of 5900 cP, 30 ¹ % of the dispersion has a viscosity of 12,000 cP and 40% of the dispersion has a viscosity of 22,300 cP.

25% dispersion of _ '’' i

a) 20 parts of said monodiglyceride ethoxylates and bj 80 parts of said fatty acid ethoxylates have a viscosity of 10,500 cP.

with 4 moles of ethylene oxide per mole of hydroxyl groups and fatty acid ethoxylates based on '4% lauric acid' myristic acid 'palmitic acid' stearic acid '-oleic acid' linoleic acid '

% of erucic acid and a small fraction of interfractions and higher fatty acids, with mixtures of 3 moles of ethylene oxide per mole of fatty acid. The 25% dispersions obtained from these mixtures show the following values:

The ratio in the mixture of monodiglyceride ethoxylate xylate ointment, k.

Vilslkloiziljtia 'at slippery slope

2.64 cm ^-1

428 cm ¹

0 100 ALIGN! 7 000 140 20 May 80 9 000 150 40 60 19 500. 260 50 50 22 000 280 60 40 29 000 340 80 20 May 22 500 290 100 ALIGN! 0 22 500 200

Example 22 parts of the monoester obtained by esterifying 1.1 moles of triethylene glycol (OH 740) with one mole of a mixture of fatty acids derived from rapeseed oil (CK 190, JC 115) is mixed with 2 parts of potassium oleate with heating. The 25% emulsion prepared from this mixture exhibits a viscosity of 21,000 cP. Adhesion and film making is good.

Claims (3)

P R E D M Ё TV Y N A L E Z U 1. A hot metal forming lubricant system, as indicated. characterized in that it consists of an aqueous dispersion or an emulsion containing 5 to 60% by weight of fatty acid monodiglyceride ethoxylates and / or ethoxylates, in that the viscosity of the dispersion or of the eatoma is preferably. based on fatty acid mixtures predominantly of 16 to 22 carbon atoms, the fatty acid monodiglyceride ethoxylates containing 2 to 6 moles, preferably 3 to 5 moles of alkylene oxide per mole of hydroxyl groups present, and fatty acid ethoxylates containing 2 to 6 moles, preferably 2.5 to 4 moles of alkylene oxide per mole ethoxylate of fatty acid and the aqueous' dispersion or emulsion has a viscosity in the range from 5000 to 40 000 cP at a shear gradient of 2.64 cm and a temperature of ¹ 30 ° C. Lubricant system according to claim 1, characterized in that it consists of a dispersion or an emulsion containing from 10 to 40% by weight of monodiglyceride ethoxylates of fatty acids and / or ethoxylates of fatty acids. 3. The system of lubricants according to claim 1, wherein tmmu, ^ E viiisikloisijlta dispersion or emulsion, is from 10 000 to 30 000 cP at a shear gradient of 2.64 cffl-1 and a temperature of ³⁰ C.