US20120115765A1

US20120115765A1 - Use of alkanolamines based on propylene oxide as additives in lubricants

Info

Publication number: US20120115765A1
Application number: US13/287,546
Authority: US
Inventors: Norbert Gutfrucht; Frank Hettche
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2010-11-04
Filing date: 2011-11-02
Publication date: 2012-05-10

Abstract

A lubricant which comprises an alkanolamine of the formula I

of the formula II

of the formula III

of the formula IV

or a mixture of alkanolamines selected from alkanolamines of the formulae I to IV,

where R1, R2, R3, R1′, R2′ and R3′ are each independently a hydrogen atom or a C1 to C4 alkyl group, and R⁴is a C1 to C16 alkyl group.

Description

The present application incorporates the provisional U.S. Application 61/410,000 filed Nov. 4, 2010 by reference.
The invention relates to lubricants which comprise an alkanolamine of the formula I
of the formula II
of the formula III
of the formula IV
or a mixture of alkanolamines selected from alkanolamines of the formulae I to IV, where R1, R2, R3, R1′, R2′ and R3′ are each independently a hydrogen atom or a C1 to C4 alkyl group, and R⁴is a C1 to C16 alkyl group.
Lubricants, especially also what are known as cooling lubricants, are used in the manufacturing industry to reduce friction and simultaneously to remove heat. Cooling lubricants are used in machine tools in order to be able to produce a maximum number of workpieces with high quality.
Lubricants, especially cooling lubricants, comprise natural or synthetic, i.e. modified, mineral oils as an essential constituent.
Frequently, aqueous lubricants are used. These are, for example, aqueous solutions of polar synthetic or correspondingly polar-modified natural mineral oils, or else aqueous emulsions in which the mineral oil has been emulsified with the aid of a surface-active compound. In the case of aqueous lubricants, there is the possibility of infestation with organic microorganisms, such as fungi or bacteria. To counteract this, biocides are added. WO 2005/055720 discloses that specific alkylethanolamines can additionally inhibit bacterial growth.
DE-A 10 2008 043 580 describes alkanolamines which can be used as additives to lubricants, have biocide-promoting action, regulate the pH and improve the emulsification of the mineral oil in aqueous lubricants.
What are desired are alternative additives to lubricants, with which the above effects are fulfilled to a maximum degree with a minimum amount added.
It was therefore an object of the present invention to provide lubricants which have good performance properties and for that purpose need contain a minimum level of simple additives. Furthermore, the additives should be very easy to prepare and, optionally, should be of minimum toxicological concern.
Accordingly, the lubricants defined at the outset have been found.
The inventive lubricants comprise an alkanolamine of the above formula I
of the formula II
of the formula III
of the formula IV
or a mixture of alkanolamines selected from alkanolamines of the formulae I to IV.
Preferably, R4 is a C1 to C8 alkyl group, especially a C1 to C4 alkyl group and more preferably a methyl group or ethyl group.
In a preferred embodiment, R1 is identical to R1, R2 to R2′ and R3 to R3′. This is the result especially of the process for preparation described below.
More particularly, R1 and R1′ are each a hydrogen atom.
In a preferred embodiment, R1 and R1′ are each a hydrogen atom, and at least one of the R2 and R3 radicals and at least one of the R2′ and R3′ radicals are each a hydrogen atom.
In particularly preferred embodiment, R1, R2, R3, R1, R2′ and R3′ are each a hydrogen atom.
In a preferred embodiment, the alkanolamine is of the formula I or II, most preferably of the formula I.
A further embodiment concerns a mixture of alkanolamines selected from alkanolamines of the formulae I to IV.
Such a mixture may, for example, comprise different alkanolamines of the formula I or consist exclusively of different alkanolamines of the formula I. The same applies to alkanolamines of the formulae II to IV.
The mixture preferably comprises alkanolamines of different formulae I to IV; especially suitable are mixtures which comprise alkanolamines of the formula I.
In addition to an alkanolamine of the formula I, the mixture especially also comprises an alkanolamine of the formula II and optionally alkanolamines of the formulae III and IV.
Particular preference is given to a mixture which consists of an alkanolamine of the formula I to an extent of more than 60% by weight, especially to an extent of more than 80% by weight.
Preferred alkanonolamines of the formula I are alkanolamines of the formula Ia:
Preferred alkanolamines of the formula II are alkanolamines of the formula IIa:
In the formulae Ia and IIa, R4 is as defined above.
Accordingly, a very particularly preferred mixture of alkanolamines is a mixture which comprises alkanolamines of the formula Ia and alkanolamines of the formula IIa. More particularly, R⁴in formulae Ia and IIa is identical.
Useful mixtures are especially those which consist to an extent of 50 to 99% by weight, especially to an extent of 80 to 99% by weight, of an alkanolamine of the formula I, especially of the formula Ia, and correspondingly to an extent of 1 to 50% by weight, especially to an extent of 1 to 20% by weight, of an alkanolamine of the formula II, especially of the formula IIa, and to an extent of 0 to 10% by weight of alkanolamines of the formulae III and IV, where the percentages by weight are based on the total weight of the alkanolamines of the formulae I to IV.
The above alkanolamines can be prepared by customary processes. The alkanolamines can be prepared especially by a two-stage addition of primary amines of the formula H₂N—R⁴onto propylene oxide or propylene oxide derivatives.
In the 1st stage, the primary amine can add onto the R², R³-substituted carbon atom of the propylene oxide or propylene oxide derivative according to the schematic diagram below:
The primary amine can alternatively also add onto the CH₃-substituted carbon atom, so as to result in the structurally isomeric addition product below.
The product of the 1st stage is therefore generally a mixture of these two addition products.
In the second stage, the secondary amine obtained again adds onto a propylene oxide or propylene oxide derivative; in the schematic diagram below, this is shown only by the example of one of the two addition products obtained in the 1st stage:
Again, it is possible for a mixture of two addition products to form here, according to which carbon atom of the epoxy group the secondary amine has added onto.
Preceding from the two addition products of the 1st stage, it is thus also possible to obtain a mixture of alkanolamines of the formulae I to IV.
The mixture obtained can be used in accordance with the invention as described above. However, it is also possible to remove a single desired alkanolamine from the mixture and use it correspondingly in lubricants.
The lubricants comprise the alkanolamine or the mixture of alkanolamines preferably in an amount of 0.05 to 30% by weight, more preferably of 0.1 to 20% by weight and most preferably of 0.5 to 10% by weight, based on the total amount of lubricant.
The alkanolamines can be added to the lubricant in any way at any time before or during use. The alkanolamines can be added directly to the lubricant which already comprises all further constituents; they can also be mixed beforehand with other constituents of the lubricant and then combined in this form with the remaining constituents of the lubricant. In one embodiment, in the case of aqueous lubricants (see below), it is possible first to prepare what are called lubricant concentrates, i.e. compositions which already comprise the constituents of the lubricant apart from the water. The latter is then added before use to the lubricant concentrates in the amount so as to result in the distribution desired for the particular use of the lubricant in the apparatus in which the lubricant is being employed.
Based on the lubricant concentrate in the case of aqueous lubricants, the total amount of the alkanolamines used in accordance with the invention is preferably at least 2% by weight, most preferably at least 5% by weight, based on the lubricant concentrate; the maximum amount is preferably 30% by weight, especially 20% by weight, likewise based on the lubricant concentrate.
The lubricants comprise, as an essential constituent, preferably a natural or synthetic lubricant component.
Natural lubricant components are, for example, mineral oils, i.e. oils which are obtained by distillation from brown coal, hard coal, peat, wood or especially mineral oil. They comprise especially saturated hydrocarbons.
Synthetic lubricant components are, for example, oils which are produced from suitable starting materials or by chemical modification of natural mineral oils (for example so-called ester oils).
Further types of lubricant components which can be used in the inventive lubricants are known to specialists in the art.
The lubricants are generally liquid under the use conditions (pressure, temperature). They are preferably liquid at 21° C., 1 bar.
A distinction is drawn between nonaqueous and aqueous lubricants. In the context of this invention, aqueous lubricants are preferred.
The aqueous lubricants may be aqueous solutions of correspondingly polar mineral oils, for example synthetic, polymeric alcohols.
The aqueous lubricants may also be emulsions of natural or synthetic mineral oils in water.
Aqueous lubricants may be marketed in the form of the solution or emulsion; another option is, however, that the solution or dispersion is not prepared from the starting materials until just before the later use.
The inventive lubricants are preferably aqueous lubricants, especially aqueous solutions of mineral oils and more preferably aqueous emulsions of mineral oils.
According to the requirement, the inventive lubricants may comprise further additives. Useful examples include additives for regulating viscosity, additives for reducing corrosion, additives for reducing foam formation, additives for reducing friction, biocides, or else other additives for improving performance properties, especially the lubrication and heat removal.
The effect of this may be that, in addition to the inventive alkanolamine or alkanolamine mixtures of the formulae I to IV or other mixtures thereof, other amines are constituents of the corresponding lubricants or lubricant concentrates, and the efficacy of the latter is enhanced by an alkanolamine of the formulae I to IV or a mixture of these alkanolamines.
The mineral oil may be self-emulsifying in the aqueous emulsions, i.e. it is chemically modified such that an emulsion in water forms without further additives. The emulsions preferably comprise, however, a surface-active compound which brings about or contributes to the emulsification of the mineral oil. Useful compounds for this purpose are customary emulsifiers and/or protective colloids.
The inventive lubricants are especially cooling lubricants; the latter not only bring about good lubrication but also ensure good heat removal, for example during the processing or production of workpieces in machine tools.
The inventive lubricants or cooling lubricants can be used in any desired fields of manufacturing technology. They are suitable for machine tools of all kinds. They have particular significance, for example, in the industrial manufacture of parts of tools or machines, and in particular of aircraft and vehicle components. In this context, the use of the inventive lubricants in the production of lightweight metal components, for example made of magnesium and aluminum, is particularly preferred.
A further field of use for the inventive lubricants or cooling lubricants involves use in conveying measures of all kinds (mining, oil extraction of all kinds). Here, for example, addition of the inventive lubricants prolongs the functioning and lifetime of the boring machine.
In addition, the inventive lubricants or cooling lubricants can be used in transmissions or turbines, for example including vehicle transmissions or transmissions of wind turbines.
Alkanolamines of the formulae I to IV or mixtures thereof, regulate the pH and bring about corrosion protection.
It is an advantage of the inventive lubricants that the alkanolamines additionally contribute to emulsification of the mineral oil, and so it may optionally even be possible to dispense with further surface-active compounds.
Furthermore, the alkanolamines of the formulae I to IV and mixtures thereof promote the action of the biocide component, and thus the efficacy toward bacteria, for example mycobacterium, or toward fungi.

Claims

1. A lubricant which comprises an alkanolamine of the formula I

of the formula II

of the formula III

of the formula IV

2. The lubricant according to claim 1, wherein R4 is a C1 to C4 alkyl group.

3. The lubricant according to claim 1 or 2, wherein R¹is identical to R^1′, R²to R^2′, and R³to R^3′.

4. The lubricant according to any of claims 1 to 3, wherein R1, R2, R3, R1′, R2′ and R3′ are each a hydrogen atom.

5. The lubricant according to any of claims 1 to 4, which is a mixture of alkanolamines comprising alkanolamines of the formulae I and II.

6. The lubricant according to any of claims 1 to 5, which is a mixture of alkanolamines consisting to an extent of at least 80% by weight of an alkanolamine of the formula I.

7. The lubricant according to any of claims 1 to 6, which comprises the alkanolamine or the mixture of the alkanolamines in amounts of 0.05 to 30% by weight.

8. The lubricant according to any of claims 1 to 7, which comprises aqueous lubricants.

9. The lubricant according to any of claims 1 to 8, which comprises aqueous solutions or emulsions.

10. The lubricant according to any of claims 1 to 9, which comprises aqueous solutions or emulsions of synthetic or nonsynthetic mineral oils.

11. The lubricant according to any of claims 1 to 10, which comprises further additives selected from additives for adjusting viscosity, additives for reducing corrosion, additives for reducing foam formation, additives for reducing friction, biocides and optionally other additives for improving performance properties.

12. The lubricant according to any of claims 1 to 11, which comprises cooling lubricants.

13. The use of lubricants according to any of claims 1 to 11 as lubricants in the manufacture of components or in conveying activities.

14. The use of lubricants according to any of claims 1 to 11 in transmissions or turbines.