WO2001060958A1

WO2001060958A1 - Lubricant containing carbon dioxide for forming metals

Info

Publication number: WO2001060958A1
Application number: PCT/EP2001/001443
Authority: WO
Inventors: Augusto Peruggia
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 2000-02-18
Filing date: 2001-02-09
Publication date: 2001-08-23
Also published as: EP1257622A1; CZ20022810A3; DE10007625A1

Abstract

The invention relates to the use of carbon dioxide esters of general formula (I) in lubricants for forming metals under the effects of sliding friction. In said formula: R and R' can be identical or different and each represent a linear or branched alkyl group, a cycloalkyl group or an alkyl-cycloalkyl group, each with between 5 and 30 C atoms. The invention also relates to lubricants containing carbon dioxide esters of general formula (I) and one or more components selected from a) mono and/or diesters of mono or oligophosphoric acids with between 1 and 6 P atoms having linear or branched fatty alcohols with between 12 and 22 C atoms, or their non-esterified starting products b) triglycerides of fatty acids with between 12 and 22 C atoms and c) methyl esters of fatty acids with between 12 and 22 C atoms. The lubricants are preferably devoid of mineral oil.

Description

LUBRICANTS CONTAINING CARBONIC ESTERS FOR FORMING METALS

The invention is in the field of cold forming of metals, such as drawing tubes, wires and profiles, massive cold forming and cold shaping of components, for example by deep drawing or cold extrusion. These processes have in common that the forming process is associated with a strong sliding friction between the tool and the workpiece, the starting or static friction having to be overcome in particular at the beginning of the forming process. During the forming process, there can be "chattering" or "stick-slip" effects, with the type of friction alternating between sliding and static friction at short intervals. The above-mentioned forming processes differ from cold rolling of metal strips in which mainly rolling friction occurs between the metal substrate and the rolls. A lubricant is used to reduce the sliding and static friction between the tool and the workpiece in the above-mentioned processes. The present invention relates to such a lubricant.

Conventional lubricants for the applications mentioned are based on mineral oil or similar hydrocarbons such as petroleum distillates. Such substances are not biodegradable under the normal conditions of an industrial or municipal sewage treatment plant and are accordingly difficult and costly to dispose of.

EP-A-393 749 discloses the use of selected carbonic acid esters, referred to there as organic carbonates, for rolling processes. EP-A-89 709 describes lubricants which contain such carbonic acid esters for lubrication processes in which no metal deformation takes place. Examples are lubricants for internal combustion engines or the use in industrial lubrication, for example in the form of gear oils or compressor oils. No metal deformation occurs in the lubrication processes according to EP-A-89 709 and the aim is to minimize the sliding friction between metal parts as much as possible. The forming processes by rolling according to EP-A-398 749 take place by rolling friction, whereby sliding friction between the rolls and the metal substrate should also be kept as low as possible.

In contrast to this, the present invention relates to metal forming processes by cold shaping, with strong sliding friction occurring between the tool and the workpiece. Since considerably greater frictional forces occur here than in the processes according to EP-A-89 709 and EP-A-393 749, it cannot be assumed that lubricants which are suitable for these processes are also used in the cold forming of metals with sliding friction can be.

The aim of the present invention is to provide lubricants for cold forming which are less complicated to dispose of and which preferably have an improved lubricating effect than conventional hydrocarbon-based lubricants.

The invention is based on the surprising finding that the carbonic acid esters described in EP-A-89 709 and EP-A-393 749 can also be used for the purposes according to the task. This is especially true when they are supplemented with components that serve as a replacement for hydrocarbons such as mineral oil or petroleum distillates.

The invention thus relates in a first aspect to the use of carbonic acid esters of the general formula (I)

RO-C-OR '

II (I)

O where R and R 'may be the same or different and each represent a linear or branched alkyl radical, a cycloalkyl radical or an alkyl-cycloalkyl radical each having 5 to 30 carbon atoms, in lubricants for forming metals with sliding friction.

Such carbonic acid esters can be produced by transesterification of carbonic acid esters of lower alcohols (for example alcohols with 1 to 3 C atoms) with the less volatile alcohols with 5 to 30 C atoms. Further information on the production of these carbonic acid esters can be found in the two documents cited at the beginning.

The alkyl groups R and R 'of the alcohol component of the carbonic acid esters can correspond to primary, secondary or tertiary alcohols. The radicals R and R 'preferably represent linear or branched alkyl groups having 6 to 30, in particular having 10 to 20, carbon atoms.

For the purposes of the present invention, the carbonic acid esters of the general formula (I) are preferably used in lubricants which contain no mineral oil. For the stated use, lubricants are preferably used which, in addition to carbonic acid esters of the formula (I), have one or more components selected from: a) mono- and / or diesters of mono- or oligophosphoric acids having 1 to 6 P atoms with linear or branched fatty alcohols Contain 12 to 22 carbon atoms or their non-esterified starting products, b) triglycerides of fatty acids with 12 to 22 carbon atoms and c) methyl esters of fatty acids with 12 to 22 carbon atoms.

Furthermore, the lubricants for the use mentioned can additionally have one or more components selected from: d) terpenes, e) pour point depressants and f) alkylamines of the general formulas (IIa) and (IIb)

R "-NH ₂ (lla)

R "- [NH- (CH ₂ ) _n -] _m NH ₂ (llb) contain, where R "is a linear or branched, saturated or mono- or polyunsaturated alkyl group having 8 to 22 carbon atoms, n is an integer in the range from 1 to 4 and m is an integer in the range from 1 to 4.

With a suitable choice of components, lubricants which contain carbonic acid esters of the general formula (I) can be used not only for forming metals under sliding friction, but generally for lubrication purposes. Accordingly, the invention relates in an expanded aspect to lubricants containing carbonic acid esters of the general formula (I)

RO-C-OR '

II (D

O

where R and R 'may be the same or different and each represent a linear or branched alkyl radical, a cycloalkyl radical or an alkyl-cycloalkyl radical each having 5 to 30 carbon atoms, and one or more components selected from a) mono- and / or diesters of mono- or oligophosphoric acids with 1 to 6 P atoms with linear or branched fatty alcohols with 12 to 22 C atoms or their non-esterified starting products, b) triglycerides of fatty acids with 12 to 22 C atoms and c) methyl esters of fatty acids with 12 to 22 carbon atoms.

Here, too, it is preferred that the new lubricant additionally has one or more components selected from d) terpenes, e) pour point depressants and f) alkylamines of the general formulas (IIIa) and (IIb)

R "-NH ₂ (lla)

R "- [NH- (CH ₂ ) _n -] _m NH ₂ (llb) contains, where R "is a linear or branched, saturated or mono- or polyunsaturated alkyl group having 8 to 22 carbon atoms, n is an integer in the range from 1 to 4 and m is an integer in the range from 1 to 4.

For the purposes of the present invention, these agents are also preferably free of mineral oil.

The lubricant according to the invention is specifically characterized in that it is based on the entire lubricant

8 to 15% by weight of carbonic acid esters of the general formula (I) and one or more of the following components: a) 8 to 42% by weight of mono- and / or diesters of mono- or oligophosphoric acids with 1 to 6 P atoms with linear or branched fatty alcohols with 12 to 22 C atoms or their non-esterified starting products, b) 20 to 38% by weight triglycerides of fatty acids with 12 to 22 C atoms, c) 3 to 25% by weight, preferably 5 to 25% by weight of methyl esters of fatty acids with 12 to 22 carbon atoms and

It is preferred that the lubricant additionally contains one or more of the following components: d) 5 to 25% by weight, preferably 5 to 10% by weight of terpenes, e) 0.1 to 0.5% by weight Freezing point depressant, f) 3 to 8% by weight of alkylamines of the general formulas (IIIa) and (Mb), the proportions being chosen so that their total gives a maximum of 100% by weight and a remainder of 100% by weight. -% consists of other active substances and / or auxiliary substances.

Component a) can in particular take on the task of so-called high-pressure additives (Anglo-Saxon “extreme pressure additive”, EP additive for short). Molybdenum or tungsten is used because of the use of component a) Additives that make it difficult to dispose of used lubricants are dispensed with. Accordingly, a preferred embodiment of the lubricant according to the invention is that it is free from heavy metals and from chlorine and sulfur compounds.

Components a) to f) are described in more detail below.

Component a) are mono- and / or diesters of mono- or oligophosphoric acids with 1 to 6 P atoms with linear or branched fatty alcohols with 12 to 22 C atoms or their non-esterified starting products. In practice, this component is incorporated into the lubricants by mixing mono- or oligophosphoric acids with 1 to 6 P atoms or their anhydrides with the fatty alcohols. In some cases, at least in part during the production of the lubricants, but also only at least partially under the elevated temperatures of use, ester formation occurs between the phosphoric acids or their anhydrides and the fatty alcohols. It is therefore not necessary to synthesize the esters in a separate step prior to the preparation of the lubricant according to the invention. Due to the thermodynamics and the kinetics of the ester formation, it can be expected that the lubricant contains a mixture of mono- and diesters and possibly non-esterified phosphoric acids or alcohols. For example, tetraphosphoric acid with 4 P atoms can be used as the oligophosphoric acid. Their anhydride is also suitable. The alcohol component can be, for example, a technical fatty alcohol mixture that can be obtained by splitting and reducing natural oils and fats. Such reaction products of natural fats and oils usually contain a mixture of fatty alcohols with different carbon chain lengths. For example, components with 14 to 20 C atoms can be present, the majority having 16 to 18 C atoms. For example, component a) in the ready-to-use lubricant can consist of approximately 60 to 80% monoesters, 10 to 20% diesters and 10 to 20% free phosphoric acid. If the anhydride is used instead of the phosphoric acid, the content of free phosphoric acid in the ready-to-use lubricant is reduced in favor of the phosphoric acid ester. So can products are obtained in which component a) is composed, for example, of about 60 to 70

% Diesters and about 30 to 40% monoesters and almost no free acid.

Component b) is one of the components that makes it possible to dispense with mineral oil. These can be natural oils or fats or conversion products thereof, provided that they are either liquid at the application temperature or dissolve in the remaining liquid components. Substances that are liquid at room temperature are preferred as component b). This means that the fatty acid components of the triglycerides are preferably at least partially unsaturated. For example, triglycerides with a high proportion of oleic acid are suitable. As is usual with natural oils and fats and their derivatives, the triglycerides are present as mixtures of molecules that contain different fatty acid components.

Component c) are methyl esters of fatty acids with 12 to 22 carbon atoms. These can be obtained by transesterifying natural fats and oils with methanol. Accordingly, there are usually products which are mixtures of methyl esters with fatty acids of different chain lengths. Such fatty acid methyl esters are also known as “biodiesel” because they are suitable as an alternative to diesel as a fuel for internal combustion engines. Together with or instead of component b), the methyl esters serve as a substitute for mineral oil in the lubricants according to the invention.

Component d) can be a mixture of terpenes, possibly mixed with other natural products. Such terpene mixtures can be obtained industrially by distilling plant seeds. These distillation products from plant seeds generally contain a very complex mixture of individual molecules, with linear unsaturated hydrocarbons, alcohols and aldehydes also occurring in addition to the terpenes. Terpenic distillates of this type are commercially available as components of lubricants, for example the Globeoil ^R products from DE.FI.LU (Italy). These terpenes can also be regarded as substitutes for mineral oil in the formulations according to the invention.

Component e) are pour point depressants which can be added to the lubricant according to the invention if its pour point or pour point is to be lowered. It depends on the choice of the other components whether such pour point depressants are required. Suitable products are known in the field of lubricating oil preparation. For example, ethylenediaminetetraacetate tetraamide or derivatives thereof can be used.

The alkylamines of component f) can in turn be regarded as a substitute for mineral oil. Such monoamines or oligoamines are known, for example, as components of belt lubricants in the beverage industry. Oligoamines of the general formula (IIb) can be used as component f). For economic reasons, however, monoamines of the general formula (IIIa) are preferred. These alkylamines are usually derived from fatty alcohols, which can be obtained by splitting and reacting natural fats and oils. Accordingly, these amines are often in the form of molecular mixtures with different radicals R ". The radicals R" can be saturated or mono- or polyunsaturated. Amines in which the R "radical contains 12 to 20 C atoms are particularly suitable. An example of this is the oleyl radical.

The products according to the invention can be produced free of mineral oils and also free of heavy metals and of chlorine and sulfur compounds. The lubricating components are based at least largely on renewable raw materials such as vegetable or animal oils and fats. Disposal is simplified because the ingredients can be degraded in industrial or municipal wastewater treatment plants. In addition to these ecological advantages, however, the lubricants according to the invention also have technical advantages: their viscosity is reduced by up to 25% in comparison to common oil-based products, which makes application easier. The drawing speed can be increased compared to mineral oil based products, even one reduced surface roughness is achieved than with mineral oil products. At the

Tubing can be reduced by 40 to 50% in one drawing step.

Claims

claims

1. Use of carbonic acid esters of the general formula (I)

RO-C-OR '

II (I)

O

where R and R 'may be the same or different and each represent a linear or branched alkyl radical, a cycloalkyl radical or an alkyl-cycloalkyl radical each having 5 to 30 carbon atoms, in lubricants for forming metals with sliding friction.

2. Use according to claim 1, characterized in that the lubricants do not contain mineral oil.

3. Use according to one or both of claims 1 and 2, characterized in that the lubricants apart from carbonic acid esters of the formula (I) one or more components selected from: a) mono- and / or diesters of mono- or oligophosphoric acids with 1 to 6 P atoms with linear or branched fatty alcohols with 12 to 22 C atoms or their non-esterified starting products, b) triglycerides of fatty acids with 12 to 22 C atoms and c) methyl esters of fatty acids with 12 to 22 C atoms.

4. Use according to claim 3, characterized in that the lubricants additionally one or more components selected from: d) terpenes, e) pour point depressants and f) alkylamines of the general formulas (IIIa) and (IIb)

R "-NH ₂ (lla) R "- [NH- (CH ₂ ) _n -] mNH ₂ (llb)

contain, where R "is a linear or branched, saturated or mono- or polyunsaturated alkyl group having 8 to 22 carbon atoms, n is an integer in the range from 1 to 4 and m is an integer in the range from 1 to 4.

5. Lubricant containing carbonic acid esters of the general formula (I)

RO-C-OR '

II (I) o

6. Lubricant according to claim 5, characterized in that it additionally contains one or more components selected from d) terpenes, e) pour point depressants and f) alkylamines of the general formulas (IIIa) and (IIb)

R "-NH ₂ (lla)

R "- [NH- (CH ₂ ) n-] _m NH ₂ (llb)

contains, where R "is a linear or branched, saturated or mono- or polyunsaturated alkyl group having 8 to 22 carbon atoms, n is an integer in Range from 1 to 4 and m are an integer in the range from 1 to 4.

7. Lubricant according to one or both of claims 5 and 6, characterized in that it is free of mineral oil

8. Lubricant according to one or more of claims 6 to 7, characterized in that it is based on the entire lubricant

8 to 15% by weight of carbonic acid esters of the general formula (I) and one or more of the following components: a) 8 to 42% by weight of mono- and / or diesters of mono- or oligophosphoric acids with 1 to 6 P atoms with linear or branched fatty alcohols with 12 to 22 C atoms or their non-esterified starting products, b) 20 to 38% by weight triglycerides of fatty acids with 12 to 22 C atoms, c) 3 to 25% by weight methyl esters of fatty acids 12 to 22 carbon atoms.

9. Lubricant according to claim 8, characterized in that it additionally contains one or more of the following components: d) 5 to 25 wt .-% terpenes, e) 0.1 to 0.5 wt .-% pour point depressants, f) 3rd up to 8% by weight of alkylamines of the general formulas (IIIa) and (IIb), the proportions being chosen so that their total amounts to a maximum of 100% by weight and the remainder being 100% by weight from further activity - And / or auxiliary materials.

10. Lubricant according to one or more of claims 5 to 9, characterized in that it is free from heavy metals and from chlorine and sulfur compounds.