DE2700040C2 - Lubricant system for the hot forming of metals - Google Patents

Description

The invention relates to a lubricant system for the hot forming of metals. In particular, relates the invention relates to water-containing, environmentally friendly lubricant systems for non-cutting metalworking such as B. rolling or pulling are suitable and have sufficient lubrication or separating effect between the tools used and the materials to be deformed.

The previously known lubricant systems z. B. tar or mineral oil based have disadvantages. The constant Cooling of the tools with water - in the case of hot rolling mills with large amounts of water - leaves Cracked products and undecomposed mineral oil get into the cooling water circuit. The deposition of the Substances that are difficult to biodegrade and that would pollute the wastewater in an unacceptable manner cause considerable Costs and affects the economics of the process.

Products containing tar and mineral oil decompose thermally due to the high temperatures of the workpieces with the formation of thick clouds of smoke and soot, which must be removed for reasons of workplace hygiene is, which also involves considerable investment.

After short periods of operation, lubricant residues cover the fittings and scaffolding in the form of a thin film that is difficult to remove. Smooth objects coated with oil can stabilize the operational sequence and cause slipping or slipping Cause accidents.

The invention is therefore based on the object of providing a lubricant for the hot forming of metals, in particular for the hot rolling of steel, which has the disadvantages of the known lubricants based on mineral oil avoids problem-free application with the usual fittings, Pumps, nozzles etc. allow good film formation

ίο shows on the tools used and that has excellent adhesion after application to damp metal surfaces, even then _; when the tools are cooled by running water.

This object is achieved according to the invention in that a lubricant system is provided which consists of an aqueous dispersion or emulsion with contents of 5 to 60% by weight of fatty acid monodiglyceride ethoxylates and / or fatty acid ethoxylates, the fatty acid monodiglyceride ethoxylates 2 to 6 mol, preferably 3 to 5 mol Alkylene oxide per mole of hydroxyl groups present and the fatty acid ethoxylates contain 2 to 6 moles, preferably 2.5 to 4 moles, of alkylene oxide per mole of fatty acid ethoxylate and the aqueous dispersion or emulsion has a viscosity between 5000 and 40,000 mPa.s at a shear rate of 2, 64 cm ^-1 and a temperature of 30 ° C.

The reaction products with preferably ethylene oxide or optionally propylene oxide are used as ethoxylates Understood.

Fatty acid ethoxylates and fatty acid partial glyceride ethoxylates are known and are produced by direct conversion the fatty acids or Fetisäurepartiaigiyceride made with ethylene oxide or optionally propylene oxide, whereby Alkoxy chains bound predominantly on one side to the OH groups of the fatty acids or the partial glycerides which terminate with H atoms.

Mixtures of the fatty acid monodiglyceride ethoxylates are preferred with fatty acid ethoxylates, especially those with at least 10, as a rule at least 20% by weight of one of the two components; However, mixtures of the fatty acid monodiglyceride ethoxylates are also possible with one another and possibly mixtures of the fatty acid ethoxylates with one another.

Monodiglycerides are understood as meaning mixtures free from triglycerides or with reduced contents of triglycerides, the mono- and diglyceride content of which generally does not deviate from 30 to 100% by weight, preferably 55 to 90% by weight. The fatty acid residues of the partial glycerides or fatty acids can be saturated or unsaturated; Residues of hydroxy fatty acids should not be included.
Although lubricants with contents of fatty acid ethoxylates have already been proposed in DE-OS 24 46 319, a water-soluble lubricant is produced there with a different task which, when diluted with water, forms true transparent or semi-transparent solutions.

The lubricant solution according to DE-OS 24 46 319 are disadvantageous because of their low viscosity and therefore poor adhesion to the tool. From with flowing Water-cooled tools will wash off these lubricants and are therefore theirs Unsuitable lubrication.

Another disadvantage of the lubricants of DE-OS 24 46 319 is the cumbersome production three components, viz

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(A) water-soluble substances with prolonged alkoxy

chain,
(8) Oil-soluble substances with a shorter alkoxy chain

and
(C) a surfactant.

According to what has been said, the object of the present invention could not be achieved by DE-OS 24 46 319 will.

The suspension or emulsion preferably contains 10 to 40% by weight of the ethoxylates, with increasing contents the ethoxylates increase the viscosity and so there is a possibility of adjusting the viscosity The second possibility of adjusting the viscosity is through the length of the alkoxy chain, with numerous In cases of longer alkoxy chains lower the viscosity. However, those have a further influence on the viscosity Degree of distribution of the ethoxylates in the aqueous phase of the dispersion or emulsion, the chain length of the fatty acids and the content of the mono- or diglycerides in the partial glycerides, so that from the chemical analysis certain ethoxylation products of partial glycerides or fatty acids affect the viscosity of the aqueous dispersion cannot be predicted with sufficient accuracy.

It is therefore intended to determine the desired specific viscosity of a specific product, if necessary after measuring the viscosity of the approaches, by simply mixing dispersions with higher and dispersions with lower viscosities to adjust the viscosity determined for the respective use.

Preferred degrees of ethoxylation are fatty acid monodiglyceride ethoxylates between 3 and 5 moles of ethylene oxide per hydroxyl group of the partial glycerides, in the case of fatty acid ethoxylates between 2.5 and 4 moles of ethylene oxide per mole of fatty acid.

The dispersions or emulsions have the considerable advantage that they form spontaneously. It was found that the aqueous dispersion or emulsion of fatty acid monodiglyceride ethoxylates with a degree of ethoxylation of less than 2 moles of ethylene oxide per mole of hydroxyl groups and / or fatty acid ethoxylates with less than 2 moles of ethylene oxide per mole of fatty acid give adequate adhesion to damp metal surfaces such as water-cooled rollers However, the build-up of a uniform lubricating film is not guaranteed. The film tears off at particularly smooth or heavily water-exposed areas, which ultimately results in increased tool wear.

Aqueous dispersions or emulsions of fatty acid monodiglyceride and / or fatty acid ethoxylates with a degree of ethoxyiation of more than 6 moles of ethylene oxide per mole of hydroxyl group or fatty acid, on the other hand, show poor adhesion to moist metal surfaces, so that a reliable application of the lubricating film, for example by jetting on rotating, water-sprayed rollers, is not possible, as the lubricating film is quickly washed out.

It has also been found that the lubricant system according to the invention has a viscosity between 5000 and 40,000 mPa · s, preferably between 10,500 and 00OmPA ■ s, measured under the specified conditions, must have.

The required viscosity measurements were made with the Rotovisko rotational viscometer from Gebr. Hanke performed. The temperature-controlled cou-

etteeinrichtung MV II P used in combination with the measuring head 500, which by a special shape is particularly suitable for the investigation of dispersions or emulsions. Details are the company font »Rotovisko, Description and Instructions for Use«, Publication 105/16, as well as the article by W. Heinz, Rheology and Rheometry with Rotational Viscometers, 2nd edition, Springer-Verlag, Berlin, can be found.

The viscosity ranges mentioned above were found at a shear rate of 2.64 cm- 'and a temperature of 30 ⁰ C. lubricant compositions 5000 and about 40,000 mPa · s, even if contained therein are ethoxylates with appropriate substances or the composition of the invention , are not suitable for solving the task at hand.

Lubricants with viscosities below 5000 mPa.s show insufficient adhesion on moist metal surfaces and therefore cannot be used in practice. An upper limit of the viscosity range of the invention On the other hand, the lubricant system is given by the fact that the promotion and application the aqueous dispersion or emulsion with the usual operational facilities such. B. pumps, nozzles and the like must be guaranteed. In addition, viscosities above 40,000 mPa.s are also undesirable because because there are difficulties in uniformly applying the lubricating film.

The lubricant system according to the invention also shows what is known as a plastic viscosity behavior. Associated with this is the presence of a flow limit which ^{exceeds the value 50 dyn · cm-2} (obtained according to the relaxation method after a relaxation time of 30 seconds). Corresponding to this behavior, a decrease in viscosity with increasing shear rate is observed. The lubricant system according to the invention thus gives viscosity values between 100 and 50OmPa.s at a shear gradient of 428 cm- 'and a temperature of 30 ° C.

The viscosity range according to the invention can be set by varying the concentration of the Fatty acid monodiglyceride and / or fatty acid ethoxylates take place. So have dispersions or emulsions with a higher ethoxylate content generally a higher viscosity and vice versa. The desired viscosity however, the aqueous dispersions or emulsions can also be produced by mixing from Z. B. two ethoxylation products, one of which as an individual component in the corresponding dispersion or emulsion results in a low viscosity and the other used as an individual component a high viscosity.

The fatty acid residues of the ethoxylates used in the lubricant system according to the invention are derived from fatty acids with 12 to 22 carbon atoms such as Lauric, myristic, palmitic, stearic, palmitolein, oil, Linoleic, linolenic, arachidonic, erucic acid or mixtures of these fatty acids, preferably mixtures of fatty acids with 16 to 22 carbon atoms

men.

The production of the ethoxylates can be particularly advantageous based on natural raw materials such. B. palm oil, Peanut oil, cottonseed oil, soybean oil, sunflower oil, linseed oil, rapeseed oil, lard, beef

tallow, whale oil, herring oil. The fatty acid monodiglyceride ethoxylates can be produced by known methods, e.g. B. by transesterification of the above Fats or oils with glycerine or by adding

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Esterification of the fatty acids obtained by splitting fats with glycerine and subsequent ethoxylation with the specified amounts of ethylene oxide. The Fettäuräthoxyiate can, for. B. by the addition of Ethylene oxide to the fatty acids obtainable by splitting fats or by esterifying Fatty acids are produced with polyethylene glycols of the appropriate chain length.

The production of the lubricant system according to the invention is carried out by introducing the fatty acid monodiglyceride and / or fatty acid ethoxyates in water. Since the dispersion or emulsion is formed spontaneously, can after distributing the ethoxylates in the aqueous phase of further measures such. B. Homogenize be disregarded. The aqueous dispersions or emulsions obtained in this way are immediate ready for use after production, but can also, since they have good stability, essentially unchanged over a longer period of time z. B. be stored for several weeks. In the latter case it is It is advisable to prevent microbial decomposition by adding one of the usual preservatives. Furthermore, other additives such as corrosion inhibitors, vapor phase inhibitors, Incorporate small amounts of antioxidants and the like into the lubricant system according to the invention.

In the case of using fatty acid ethoxylates without any addition of fatty acid monodiglyceride ethoxylates it is appropriate to use a small amount of a sodium or potassium salt of a fatty acid with 12 to 22 carbon atoms to be used in the production of the corresponding dispersions or emulsions. This facilitates the formation of the dispersion or emulsion and the application of the lubricating film takes place more even.

The lubricant system according to the invention meets requirements for reasons of environmental protection to an increasing extent must be made to the use of auxiliary materials in the industrial sector. So can just by using a z. B. 25% dispersion or emulsion according to the invention a reduction in organic material compared to the use of mineral oil-based lubricating systems, to achieve a quarter.

The lubricant system according to the invention is readily biodegradable, so that it gets into the wastewater Leftovers are only a minor burden. For example, when it comes to hot rolling steel, it is the largest anyway After the water has evaporated, part of the organic material burns as it exits the nip, the proportions to be taken into account are extremely small. When using the invention Compared to its behavior, the lubricant system contains more mineral oil Substances recorded a significant reduction in soot and smoke formation. An odor nuisance, as is the case with the use of mineral oil-containing systems through the formation of malodorous Cracking products occurs is not observed when using the lubricant system according to the invention.

The lubricant system according to the invention shows excellent adhesion to moist metal surfaces and can therefore, although dispersible or emulsifiable in water, on water-cooled rollers apply, forming an even film of lubricant. On the other hand, lubricant residues that possibly with the application, z. B. by spraying on the roll stands and fittings in the operational application, for example by rinsing with a powerful jet of water remove completely and easily in a simple manner.

The lubricant system according to the invention is used in a preferred manner in hot honeycombs of steel profiles. It shows a uniform formation of the lubricating film, good adhesion to the Rollers and a sufficient lubricating and separating effect.

The lubricant system according to the invention is described in more detail in the following examples. Percentages Unless otherwise stated, relate to percent by weight.

The OH number is the hydroxyl number, the acid number is the acid number and as IZ the iodine color number, the latter understood as a measure of double bonds, their determination according to DGF standard methods (German Society for Fat Science) Department D-IV 2b (61) or C-IV 4a (52).

Comparative example 1

25 parts of a fatty acid monodiglyceride ethoxylate (from partial glyceride with 46% mono- and 50% diglycerides) based

55% caprylic acid (C ₈ )
4O% capric acid (Cio)
as well as lower proportions of
Caproic and Lauric Acids

with 4 moles of ethylene oxide per mole of hydroxyl groups in the partial glyceride mixture were mixed with 75 parts of water mixed. The mixture had a viscosity which was considerably below the value of 5000 mPa.s and could no longer be precisely determined with the above-mentioned measuring arrangement. The mixture showed a insufficient adhesion on damp metal surfaces.

Comparative example 2

25 parts of a fatty acid monodiglyceride ethoxylate (42% mono- and 48% diglycerides) based on a Fatty acid mixture obtained from lard with 1.9 moles of ethylene oxide per mole of hydroxyl groups present was dispersed in 75 parts of water. The mixture had a measured viscosity of 7200 mPa.s at a shear gradient of 2.64 cm- 'and a temperature of 30 ° C. During the test it was found Adequate adhesion to damp metal surfaces, but the applied lubricating film was uneven and tends to tear off.

Comparative example 3

25 parts of a fatty acid monodiglyceride ethoxylate (42% mono- and 48% diglycerides) based on the in Comparative example 2 used fatty acid mixture with 6.25 moles of ethylene oxide per mole of hydroxyl group were mixed with 75 parts of water. The mixture had a viscosity of 4800 mPa.s, measured below the conditions given above, and resulted in a thin, very poorly adhering lubricating film.

example 1

25 parts of a fatty acid monodiglyceride ethoxylate (42% mono- and 48% diglycerides) based on a Fatty acid mixture obtained from lard n; it

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4 moles of ethylene oxide per mole of hydroxyl group was dispersed in 75 parts of water. It became an opaque one Obtained emulsion with a viscosity of 13,000 mPa.s. The emulsion showed excellent adhesion on damp metal surfaces and formed a coherent, stable protective film.

Example 2

25 parts of a fatty acid ethoxyate based on a rapeseed oil fatty acid with 3 moles of ethylene oxide per mole of fatty acid were dispersed in 75 parts of water. The aqueous dispersion had a viscosity of 6500 mPa · s and showed both sufficient adhesion and film formation behavior.

Examples 3 to 5 The 25% strength dispersion from

a) 20 parts of said monodiglyceride ethoxylate

and

b) 80 parts of the fatty acid ethoxyate mentioned gave a viscosity of 10,500 mPa.s.

The 25% dispersion from
a) 70 parts of said monodiglyceride ethoxylate

and

b) 30 parts of the fatty acid ethoxylate mentioned gave a viscosity of 24,500 mPa.s.

Examples 12-18

From a fatty acid monodiglyceride ethoxylate (36% mono- and 54% diglycerides) based on a fatty acid mixture the end

Mixtures of the fatty acid ethoxylate, potassium oleate and water mentioned in Example 2 were herge represents. The following viscosities were obtained.

Fatty acid ethoxylate 30th 35 40 (Parts) Potassium oleate (parts) 1 1 1 Water (parts) 69 64 59 Viscosity mPA · s 15 700 16 400 28 800

Adhesion and film formation of the blends were good. Examples 6-11

25 parts of a mixture of a) 48 parts of a fatty acid monodiglyceride ethoxylate (40% mono- and 50% diglycerides) based on a fatty acid mixture

27% palmitic acid
12% stearic acid
48% oleic acid
8% linoleic acid
as well as small proportions of lauric, myristic and higher fatty acids 30% palmitic acid
15% stearic acid
50% oleic acid
2% linoleic acid

as well as low proportions of myristic acid and high fatty acids

with 4 moles of ethylene oxide per mole of hydroxyl group and a fatty acid ethoxylate based on a fatty acid mixture the end

4% lauric acid

3% myristic acid
19% palmitic acid

2% stearic acid
31% oleic acid

8% linoleic acid
23% erucic acid

as well as small amounts of intermediate fractions and higher fatty acids

Mixtures with 3 moles of ethylene oxide per mole of fatty acid were obtained manufactured. The 25% strength dispersions obtained from the mixtures showed the following values:

with a degree of ethoxylation of 4 mol ethylene oxide 45 mixing ratio

per mole of hydroxyl group and b) 52 parts of a fatty fatty acid ^ - fenic acid-

Acid ethoxylate based on a fatty acid ^{mixture of ethoxylate}

12% Palmitic acid 3% Stearic acid 26% Oleic acid 18% Linoleic acid 6% Linoleic acid 21% Erucic acid as well as small amounts of lauric, Myristic acid and higher fatty acids

with a degree of ethoxylation of 3 moles of ethylene oxide per Mo! Fatty acid was mixed with 75 parts of water. The emulsion obtained in this way had a viscosity of 14,500 mPa.s and adhered excellently to moist ones Metal surfaces and formed a coherent lubricating film.

The 20% dispersion of the same fatty acid monodiglyceride ethoxyate / fatty acid ethoxylate mixture had a viscosity of 5900 mPa.s., the 30% dispersion of 12.00OmPA s, the 40% of

80
100

100

80

60

50

40

20th

Viscosity of the 428 cm- ' 25% strength by weight dispersion 140 at shear rate 150 2.64 cm- ¹ 260 7000 280 9000 340 19 500 290 22,000 200 29,000 22 500 22 500

Example 19

23 parts of a monoester, which by esterification of 1.1 mol Triethy! EnglykoI (OHZ740) with 1 Moleines Fatty acid mixture obtained from rapeseed oil (SZ 190, JZ 115) were obtained with 2 parts of potassium oleate mixed with heating. The 25% strength emulsion obtained therefrom had a viscosity of 21,000 mPa.s. Adhesion and film formation were good.

Claims (5)

27 OO 040 claims: 1. Lubricant system for the hot forming of materials consisting of an aqueous dispersion or emulsion of fatty acid monodiglyceride ethoxylates and / or fatty acid ethoxylates, with a content of fatty acid monodiglyceride ethoxylates and / or fatty acid ethoxylates of 5 to 60% by weight, the fatty acid monoglyceride ethoxylates from 2 to 6 mol Alkylene oxide per mole of hydroxyl groups present and the fatty acid ethoxylates contain 2 to 6 moles of alkylene oxide per mole of fatty acid ethoxylate and the aqueous dispersion or emulsion has a viscosity between 5000 and 40,000 mPas at a shear rate of 2.64 cm ^-1 and a temperature of 30 ° C. 2. Lubricant system according to claim 1, consisting of an aqueous dispersion or emulsion of Fatty acid monodiglyceride and / or fatty acid ethoxylates based on fatty acids with 12 to 22 carbon atoms, preferably based on fatty acid mixtures with a predominant proportion of fatty acids having 16 to 22 carbon atoms. 3. Lubricant system according to claim 1, characterized by fatty acid monodiglyceride ethoxylates with 3 to 5 moles of ethylene oxide per mole of hydroxyl group of the partial glycerides. 4. Lubricant system according to claim 1, characterized by fatty acid ethoxylates with 2.5 to 4 mol Ethylene oxide per mole of fatty acid. 5. Lubricant system according to claim 1, characterized by dispersions or emulsions with a content of fatty acid monodiglyceride ethoxylates and / or fatty acid ethoxylates of 10 to 40 wt. O / o.