ESTER OILS

According to a first aspect, an ester oil, in particular for producing a hydraulic fluid and/or a lubricant, containing an esterification product from the esterification of at least one monoalcohol with at least one polycarboxylic acid, is characterized in that the monoalcohol and/or the polycarboxylic acid originates from renewable raw materials. According to a second aspect, an ester oil, in particular for producing a hydraulic fluid and/or a lubricant, containing an esterification product from the esterificati-on of at least one monocarboxylic acid with at least one dialcohol, is characterized in that the dialcohol and/or the monocarboxylic acid originates from renewable raw materials.

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Description
TECHNICAL FIELD

The invention relates to ester oil, especially for production of a hydraulic oil and/or of a lubricant, comprising an esterification product of at least one monoalcohol with at least one polycarboxylic acid. The invention further relates to an ester oil, especially for production of a hydraulic oil and/or of a lubricant, comprising an esterification product of at least one monocarboxylic acid with at least one dialcohol. The invention additionally relates to processes for preparing ester oils and to the use of ester oils.

STATE OF THE ART

Lubricants serve particularly to reduce friction and wear, to prevent corrosion, for sealing, for cooling, and to damp vibration or transmit force in mechanical systems. According to the application envisaged, lubricants are used in the solid, liquid or gaseous state.

Liquid lubricants in particular are widespread in a wide variety of different technical fields and are used, inter alia, as motor oils, turbine oils, hydraulic fluids or transmission oils.

A known class of liquid lubricant oils is that of ester-based lubricant oils, which comprise organic reaction products of carboxylic acids with alcohols as the main component. The demands on modern ester oils are varied. An ester oil has to meet the demands defined by the envisaged use, for example in terms of density, viscosity, viscosity index, solidification point, pour point, flashpoint, seal compatibility, aging resistance, toxicity and/or biodegradability.

DE 10 2006 001 768 (Cognis) describes, for example, esters based on branched Guerbet alcohols as lubricant and carrier medium for hydraulic fluids. The esters with branched alcohols can also be prepared from renewable raw materials.

DE 10 2004 034 202 (SASOL) provides ester mixtures, for example as hydraulic oils, consisting of the reaction product of a branched alcohol with a polycarboxylic acid. Branched alcohols mentioned are especially 2-alkyl-branched alcohols, preferably Guerbet alcohols. However, there is no mention of renewable raw materials.

DE 10 2006 027 602 (Cognis) describes lubricants, for example transmission, industrial and motor oils, and hydraulic oils. The base oils are present here as mixtures of hydrocarbons (mineral oil, PAOs) with high-viscosity esters (HVE), which additionally have additives to improve the viscosity index. Reaction products of carboxylic acids and alcohols are disclosed here. However, these do not originate from renewable raw materials.

However, the preparation of known esters is comparatively complex, and they are correspondingly comparatively uneconomic.

Even though ester oils per se have long been known, the economic and environmentally friendly preparation of optimized and flexibly usable ester oils is still a great challenge.

DESCRIPTION OF THE INVENTION

It is an object of the invention to provide an ester oil which belongs to the technical field mentioned at the outset, is producible in a very inexpensive and environmentally friendly manner, and especially has ideal properties for use as a lubricant oil.

A first solution to the problem is defined by the features of claims 1 and 41.

A first aspect of the invention relates to ester oil, especially for production of a hydraulic oil and/or lubricant, comprising an esterification product of at least one monoalcohol with at least one polycarboxylic acid, wherein the monoalcohol and/or the polycarboxylic acid originate from renewable raw materials.

In a process for preparing such an ester oil, especially for use in a hydraulic oil and/or a lubricant, a monoalcohol is reacted with a polycarboxylic acid to give an ester oil, the monoalcohol and/or the polycarboxylic acid originating from renewable raw materials.

In principle, the monoalcohol and/or the polycarboxylic acid may also originate from mixtures of renewable and fossil raw materials. It is thus not obligatory that the monoalcohol and/or the polycarboxylic acid originate exclusively from renewable raw materials. In a preferred variant, however, the monoalcohol and/or the polycarboxylic acid originate essentially exclusively from renewable raw materials.

A renewable raw material in this context is understood especially to mean an organic compound which is obtained by direct isolation and/or by upgrading from organic raw materials, the organic raw materials being drawn principally from the natural world. Useful organic raw materials include, for example, plants. Renewable raw materials should not be confused with non-renewable raw materials from fossil sources. The latter are, for example, degradation products from dead plants and/or animals, the formation of which takes place in geological or astronomical periods, i.e. began well before 60 000 years.

Renewable raw materials can be distinguished from non-renewable raw materials from fossil sources particularly through the proportion of the radioactive 14C carbon isotope in the raw material. Raw materials from fossil sources, owing to their age, have essentially no 14C carbon isotopes, whereas a characteristic proportion of the 14C carbon isotope is present in renewable raw materials. 14C carbon isotopes are formed constantly by nuclear reactions in the upper atmosphere of the earth, and get into the biosphere via the carbon cycle. There is essentially an equilibrium between new formation and constant radioactive decay. Accordingly, in living organisms in the biosphere (plants, animals), about the same distribution ratio of radioactive carbon (14C) to non-radioactive carbon (12C and 13C) is established as is also present in the atmosphere. The inventive ester oils, based on the carbon content, are formed from renewable raw materials preferably to an extent of at least 25 mol %, further preferably at least 50 mol %, even further preferably at least 60 mol %, especially preferably at least 70 mol %. Lubricants having a minimum proportion of 25 mol % of the total formulation from renewable raw materials (RRM) are referred to in Europe as biolubes. Further ecolabels are applied to lubricants when they consist of renewable raw materials, based on the carbon content, preferably at least 50 mol %, even further preferably at least 60 mol %, especially preferably at least 70 mol %. In both cases, criteria relating to toxicology also have to be met. In other regions, other criteria have to be observed. For instance, the designation “biopreferred” known in the USA requires particular proportions from renewable raw materials, but no statements are made regarding toxicity.

The radiocarbon method used to determine the proportion of 14C carbon isotopes is very familiar to the person skilled in the art (ASTM D6866 or DIN EN 15440). The chemically prepared samples are analyzed, for example, by the Libby counting tube method, by liquid scintillation spectrometry and/or by mass spectrometry detection in accelerators. These can also take into account the short- and long-term variations in the production of the 14C carbon isotopes over the course of periods in the history of the earth.

A particularly suitable and standardized process for determining the proportion of renewable raw materials in a product to be tested is defined, for example, in the standard ASTM D6866-08. This determines the organic content of the product originating from renewable raw materials in relation to the total organic content of the product. Inorganic carbon and substances with no carbon content are not included. The process is based on liquid scintillation spectroscopy. The measured ratio of 14C to 12C in the product to be tested is determined relative to a standard compound (oxalic acid).

The term “lubricant” is understood to mean particularly an intermediate substance which serves for reduction of friction and wear, and for force transmission, cooling, vibration damping, sealing and/or for corrosion protection. More particularly, the lubricant of interest in this context is a fluid.

A specific lubricant is, for example, a hydraulic fluid. A hydraulic fluid is especially a fluid usable for transfer of energy (volume flow, pressure) in a hydraulic system. The hydraulic liquid is preferably a hydraulic oil, which is especially water-immiscible.

As has been found, the inventive ester oils are particularly advantageous according to the first aspect, in which the monoalcohol and/or the polycarboxylic acid originate from renewable raw materials. Firstly, such ester oils have advantageous properties with regard to use as lubricants and hydraulic oils. More particularly, such ester oils simultaneously have good lubricant properties and a high air separation capacity. It has likewise been found that the ester oils have a high lifetime or aging resistance compared to known lubricant oils.

In addition, the inventive ester oils have a high flashpoint, such that use at relatively high oil sump and component temperatures is possible without risk. In addition, the pour point of the ester oils is relatively low, as a result of which the esters are also usable at low temperatures. For a liquid product, the pour point denotes the temperature at which it is still just free-flowing in the course of cooling. Thus, the inventive ester oils can be used within a broad temperature range.

The viscosity of the inventive ester oils is additionally within an ideal range for lubricant oils and hydraulic fluids. There is thus no requirement for adjustment of the viscosity by mixing with another, for example thicker, oil. It is thus also possible to use the inventive ester oils at elevated temperatures without occurrence of changes in viscosity in the ester oil, as is the case for mixed oils owing to the different vaporization properties of the individual oil components.

There is also no requirement for a usually disadvantageous addition of viscosity-modifying thickeners in the inventive ester oils, owing to the relatively high viscosity. The air separation capacity of the ester oils is thus not impaired and the problem of softening of seals, for example in hydraulic systems, barely occurs with the inventive ester oils.

Moreover, the viscosity index (VI), which characterizes the temperature dependence of the kinematic viscosity of a lubricant oil, is relatively high in the inventive ester oils. The ester oils therefore exhibit a relatively small temperature-dependent change in viscosity, which is very advantageous for most practical applications, since they are usable with relatively constant properties within a broad temperature range.

As has been found, the vaporization losses (NOACK) of the inventive ester oils are also relatively low.

Furthermore, the use of renewable raw materials enables particularly environmentally friendly and economic production. Especially through the use of renewable raw materials, the inventive ester oils are simultaneously also convincing in terms of toxicology and biodegradability. The inventive ester oils essentially all have relatively rapid and easy biodegradability.

The combination of the inventive chemical structure and the use of renewable raw materials thus enables unexpectedly economic preparation of ester oils which have surprisingly advantageous properties as lubricants.

Advantageously, the polycarboxylic acid originates from renewable raw materials. This has been found to be advantageous especially with regard to the economic viability of the preparation. More particularly, the polycarboxylic acid is producible from vegetable oils, which are already available globally in large volumes. It is additionally possible to obtain a multitude of different polycarboxylic acids from renewable raw materials or vegetable oils in relatively simple chemical process steps. Moreover, compliance with current environmental regulations or ecolabels is enabled.

However, it is also possible in principle to use, for example, polycarboxylic acid synthesized from fossil raw materials, if this appears to serve the purpose.

The polycarboxylic acid is preferably saturated. In other words, there are preferably only single bonds between the carbon atoms of the polycarboxylic acid. As has been found, ester oils with such polycarboxylic acids are especially more oxidation-resistant and stable, which is to the benefit of the lifetime or aging resistance of the ester oils.

Under some circumstances, however, mono- or polyunsaturated polycarboxylic acids can be used for specific purposes.

In a further preferred variant, the polycarboxylic acid is unbranched. In other words, the polycarboxylic acid preferably has an unbranched carbon chain, which is especially linear. This has been found to be advantageous for a multitude of applications.

In another, likewise advantageous variant, the polycarboxylic acid, however, may also be branched. Whether an unbranched or branched polycarboxylic acid is more advantageous depends on factors including the monoalcohols used for the ester oil and the desired substance properties of the ester oil. The use of branched polycarboxylic acids can under some circumstances lower the pour point and increase the flashpoint, which may be advantageous for specific applications. In addition, ester oils with branched polycarboxylic acids exhibit higher seal compatibilities under some circumstances. This aspect is addressed in more detail further down in the context of the monoalcohols.

The polycarboxylic acid preferably has 6-13 carbon atoms, especially preferably 8-13 carbon atoms. Such polycarboxylic acids can firstly be obtained economically from renewable raw materials, and secondly enable the production of a wide range of ester oils which are particularly suitable as lubricants or hydraulic oils.

In principle, however, it is also possible to provide polycarboxylic acids having fewer than 6 or more than 13 carbon atoms. According to the desired properties of the ester oils, this may even be advantageous.

More preferably, the polycarboxylic acid comprises a dicarboxylic acid. Together with monoalcohols, it is thus possible to form dicarboxylic esters which are particularly suitable as lubricants and hydraulic oils. In addition, the production of dicarboxylic acids from renewable raw materials, for example vegetable oils, is possible without any problem, which is to the benefit of economic viability.

In principle, however, it is also possible to use other polycarboxylic acids, for example tricarboxylic acids.

Advantageously, the dicarboxylic acid comprises especially adipic acid (1,6-hexanedioic acid; HOOC—C4H8—COOH), suberic acid (octanedioic acid; HOOC—C6H12—COOH), azelaic acid (nonanedioic acid; HOOC—C7H14—COOH), sebacic acid (decanedioic acid; HOOC—C8H16—COOH), dodecanedioic acid (HOOC—C10H20—COOH) and/or brassylic acid (HOOC—C11H22—COOH). These unbranched dicarboxylic acids having 6, 8, 9, 10, 12 and 13 carbon atoms can be produced from renewable raw materials or vegetable oils. In addition, these dicarboxylic acids with a multitude of monoalcohols obtainable from renewable raw materials can be used to prepare ester oils suitable for lubricants or hydraulic oils.

In principle, however, it is also conceivable to use polycarboxylic acids having three or even more carboxylic acid groups. It is also possible to use dicarboxylic acids other than the above representatives having, for example, fewer than 6 carbon atoms or more than 13 carbon atoms. For example, it is possible to use branched derivatives of adipic acid, suberic acid, azelaic acid, dodecanedioic acid and/or brassylic acid. These branched derivatives are especially methyl-branched derivatives, for example trimethyladipic acid.

It may also be advantageous to provide a mixture of at least two different polycarboxylic acids. In this case, it is firstly possible to control the properties of the ester oils more precisely, and it is secondly possible to further optimize the preparation process with a view to economic viability. Advantageously, the at least two different polycarboxylic acids originate from renewable raw materials.

In a further optional variant, the polycarboxylic acid is a cyclic polycarboxylic acid, especially a cyclic dicarboxylic acid, more preferably 1,2-cyclohexanedicarboxylic acid [CAS #: 2305-32-0; C8H12O4; Mw=172.2] and/or 1,4-cyclohexanedicarboxylic acid [CAS #: 619-82-9; C8H12O4; Mw=172.2].

In particular, the at least one monoalcohol originates from renewable raw materials. The inventive ester oils can thus be prepared particularly economically via fatty acids from vegetable oils. A multitude of different monoalcohols can be obtained from fatty acids by oleochemical means by chemical reactions known per se. Since at least two moles of monoalcohol can be converted in each case per mole of polycarboxylic acid, the use of monoalcohols from renewable raw materials additionally makes it possible to achieve a relatively high proportion of renewable raw materials in the reaction product or the ester oil. Thus, compliance with current environmental regulations or ecolabels is also simplified.

More preferably, both the polycarboxylic acid and the monoalcohols originate from renewable raw materials. It is thus possible to further improve the aforementioned advantages.

However, it is also possible in principle to use monoalcohols from fossil raw materials, if this appears appropriate to the purpose.

The at least one monoalcohol is preferably saturated. In other words, preferably only single bonds are present between the carbon atoms of the at least one monoalcohol. It is thus possible to improve particularly the oxidation resistance and stability of the ester oil.

In a particularly advantageous variant, both the polycarboxylic acid and the at least one monoalcohol are saturated. It is thus possible to greatly improve the oxidation and aging resistance.

In principle, the at least one monoalcohol, however, may also be mono- or polyunsaturated.

Advantageously, the at least one monoalcohol is unbranched. Thus, the at least one monoalcohol advantageously has an unbranched carbon chain, which is especially linear. The monoalcohol in this case is also referred to as an n-monoalcohol. This has been found to be advantageous for a multitude of applications. This is the case especially for a combination with unbranched polycarboxylic acids and particularly with unbranched dicarboxylic acids.

In another advantageous variant, the at least one monoalcohol, however, may also be branched. The use of branched monoalcohols, under some circumstances, can lower the pour point and increase the flashpoint, which may be advantageous for specific applications. In addition, ester oils with branched monoalcohols, under some circumstances, have higher seal compatibilities.

Branched monoalcohols have been found to be advantageous especially in combination with unbranched polycarboxylic acids and especially unbranched dicarboxylic acids. Branched polycarboxylic acids, especially branched dicarboxylic acids, are advantageously used in combination with unbranched monoalcohols.

In principle, however, it is also possible to use branched monoalcohols in combination with branched polycarboxylic acids.

Branched monoalcohols advantageously have a terminal iso branch. This mean, more particularly, that a methyl group is arranged or branches off at the second position of the remote end of the carbon chain from the alcohol group. Ester oils comprising monoalcohols with terminal iso branches have been found to be advantageous in practice, particularly for lubricants and hydraulic oils, and these can at the same time be prepared relatively inexpensively from renewable raw materials.

In principle, differently branched monoalcohols are also usable. Under some circumstances, however, this results in ester oils which are difficult and costly to prepare and/or are less suitable for lubricants or hydraulic oils.

The at least one monoalcohol particularly advantageously has 6-24, preferably 8-16, carbon atoms. Especially preferably, the at least one monoalcohol has 9, 11, 12, 14 and/or 16 carbon atoms. Such monoalcohols can firstly be obtained economically from renewable raw materials, and secondly enable the preparation of a wide range of ester oils which are particularly suitable as lubricants or hydraulic oils. This is the case especially in combination with a polycarboxylic acid or a dicarboxylic acid having 6-13 carbon atoms.

In principle, however, it is also possible to provide monoalcohols having fewer than 6 or more than 16 carbon atoms. According to the desired properties of the ester oils, this may also be advantageous under some circumstances.

Advantageously, the at least one monoalcohol is a fatty alcohol and especially an unbranched fatty alcohol from the group of 2-octanol (C8H18O), 1-nonanol (C9H20O), 1-undecanol (C11H24O), 1-dodecanol (C12H26O), 1-tetradecanol (C14H30O), and/or cetyl alcohol (also known as 1-hexadecanol; C16H34O). Such monoalcohols are especially obtainable economically from renewable raw materials and are particularly suitable for the inventive ester oils. It may likewise be advantageous to use mixtures of two or even more different fatty alcohols. Such mixtures are also referred to as cuts.

Fatty alcohols are commonly supplied as mixtures or cuts of various carbon chain lengths. In the present case, the following cuts are especially suitable: C8-C10 fatty alcohols and/or C16-C18 fatty alcohols. These can be used to form, for example, the following ester products: dialkyl(C8-10)nonanedioate [CAS #: 92969-93-2], dialkyl(C16-18)nonanedioate [CAS #: 92969-94-3], monoalkyl(C8-10)nonanedioate [CAS #: 92969-95-4] and/or monoalkyl(C16-18) nonanedioate [CAS #: 92969-96-5].

In a further advantageous variant, the at least one monoalcohol comprises methyltetradecanol (13-methyl-1-tetradecanol; C15H33O). This is a saturated, terminally iso-branched monoalcohol.

The monoalcohols mentioned in the last two paragraphs have been found to be advantageous particularly in combination with polycarboxylic acids, especially dicarboxylic acids having 6-13 carbon atoms, more preferably 8-13 carbon atoms. Particularly suitable combinations are those with adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and/or brassylic acid.

However, other alcohols and/or combinations with other polycarboxylic acids are also possible in principle.

More preferably, the polycarboxylic acid is a dicarboxylic acid having 12 carbon atoms, especially 1,12-dodecanedioic acid, and the at least one monoalcohol is an alcohol having 13 carbon atoms, more preferably 1-tridecanol and/or isotridecanol. Such ester oils have been found to be particularly advantageous for lubricants and hydraulic oils in terms of the preparation and the properties.

A particularly suitable esterification product in the context of lubricants and/or hydraulic oils has been found to be that of the dicarboxylic acid dodecanedioic acid and the monoalcohol isotridecanol. The diisotridecyl dodecanedioate formed [C38H74O4; Mw=595.0] is convincing especially with regard to viscometric properties (NOACK value) and flashpoint, and even as an unadditized base oil has significant advantages over known fully formulated lubricants (see also tables 2 and 3).

According to the application, however, other inventive ester oils may also be more advantageous.

A further solution to the problem addressed by the invention is defined by the features of claims 18 and 42.

A second aspect of the invention relates to an ester oil, especially for production of a hydraulic oil and/or of a lubricant, comprising an esterification product of at least one monocarboxylic acid with at least one dialcohol, the dialcohol and/or the monocarboxylic acid originating from renewable raw materials.

In a process for preparing such an ester oil, especially for use in a hydraulic oil and/or a lubricant, a dialcohol is reacted with a monocarboxylic acid to give an ester oil, the dialcohol and/or the monocarboxylic acid originating from renewable raw materials.

In principle, dialcohol and/or the monocarboxylic acid may also originate from mixtures of renewable and fossil raw materials. It is thus not obligatory that the dialcohol and/or the monocarboxylic acid originate exclusively from renewable raw materials. In a preferred variant, however, the dialcohol and/or the monocarboxylic acid originate essentially exclusively from renewable raw materials.

A dialcohol in this context is especially understood to mean an organic compound having exactly two hydroxyl groups. Dialcohols can also be referred to as diols and/or dihydric alcohols.

The inventive ester oils according to the second aspect have been found to be unexpectedly advantageous. In particular, such ester oils are suitable for lubricants and hydraulic oils. For instance, the ester oils simultaneously have good lubricant properties and high air separation capacity. It has likewise been found that the ester oils have a high lifetime or aging resistance compared to known lubricant oils.

In addition, the inventive ester oils have a high flashpoint, and so use is also possible at relatively high temperatures without risk. Moreover, the pour point of the ester oils is relatively low, as a result of which the ester oils are also usable at low temperatures. It is thus possible to use the inventive ester oils within a broad temperature range.

The viscosity of the inventive ester oils is additionally within an ideal range for lubricant oils and hydraulic fluids. Adjustment of the viscosity by mixing with another, for example thicker, oil is thus not required. It is thus also possible to use the inventive ester oils at elevated temperatures without occurrence of changes in viscosity in the ester oil, as is the case for mixed oils owing to the different vaporization properties of the individual oil components.

Addition of viscosity-modifying thickeners, which is usually disadvantageous, is also not required in the case of the inventive ester oils owing to the relatively high viscosity and the high viscosity index (VI), which characterizes the temperature dependence of the kinematic viscosity of a lubricant oil. The air separation capacity of the ester oils is thus not impaired, since emulsified air bubbles in the ester oil can be separated out more easily. In addition, the problem of softening of seals, for example in hydraulic systems, barely arises with the inventive ester oils.

Owing to the relatively high viscosity index (VI), the ester oils exhibit a relatively small temperature-dependent change in viscosity, which is very advantageous in practice for most applications, since they are usable with relatively constant properties within a broad temperature range.

As has been found, the vaporization losses (NOACK) of the inventive ester oils are also relatively low.

In addition, the use of renewable raw materials enables particularly environmentally friendly and economic production. More particularly, through the use of renewable raw materials, the inventive ester oils are simultaneously also convincing in terms of toxicology and biodegradability. Essentially all of the inventive ester oils have relatively rapid and easy biodegradability.

Compared to the ester oils according to the first aspect, monocarboxylic acids are used directly for the preparation of the ester oils in the second aspect of the invention. Monocarboxylic acids are available on the market with a wide variety of different structures, which allows the properties of the ester oils to be adjusted in a relatively simple and controlled manner through the use of specific monocarboxylic acids. In addition, the monocarboxylic acids used may also be fatty acids obtainable directly from renewable raw materials or vegetable oils. This has been found to be particularly economically viable.

The dialcohol preferably originates from renewable raw materials. This has been found to be advantageous particularly with regard to the economic viability of the preparation. Dialcohols can be produced, for example, by oleochemical means in a manner known per se. For example, a multitude of different polycarboxylic acids are obtainable by oxidative cleavage from vegetable oils, and these can then be converted by reduction to dialcohols. Corresponding vegetable oils are already available globally in large volumes. It is thus possible to obtain a multitude of different polycarboxylic acids from renewable raw materials or vegetable oils in relatively simple chemical process steps, and these can be converted to corresponding dialcohols. In addition, compliance with current environmental regulations or ecolabels is enabled.

However, it is also possible in principle to use, for example, dialcohols produced by petrochemical means from fossil raw materials, if this appears appropriate to the purpose.

The dialcohol is preferably saturated. In other words, there are preferably only single bonds between the carbon atoms of the dialcohol. It is thus possible to improve particularly the oxidation resistance and stability of the ester oil.

In principle, the dialcohol may also be mono- or polyunsaturated.

In a further preferred variant, the dialcohol is unbranched. In other words, the dialcohol preferably has an unbranched carbon chain, which is especially linear. This has been found to be especially advantageous for a multitude of applications of the ester oil.

In another, likewise advantageous variant, the dialcohol is branched, especially singly or multiply methyl-branched. This means, more particularly, that the dialcohol has a carbon chain from which at least one methyl group (—CH3) branches off. More particularly, the dialcohol may, for example, be a trimethylhexanediol (TMH). Together with isononanoic acid, the result is, for example, an esterification product with low thermal viscosities and pour points (η100° C.=4.56 mm2/s, η−40° C.=14.165 mm2/s (capillary), VI=123, pour point=−51° C.)

Whether an unbranched or branched dialcohol is more advantageous depends upon factors including the monocarboxylic acids used for the ester oil and the desired substance properties of the ester oil. The use of branched dialcohols, under some circumstances, can lower the pour point and increase the flashpoint, which may be advantageous for specific applications. In addition, ester oils with branched dialcohols, under some circumstances, have higher seal compatibilities. Especially methyl branches have been found to be particularly advantageous.

In principle, however, in place of or in addition to methyl branches, other branches are also possible, for example ethyl and/or propyl branches.

Advantageously, the dialcohol has 5-14 carbon atoms. Such dialcohols can firstly be obtained economically from renewable raw materials, and secondly enable the production of a wide range of ester oils which are particularly suitable as lubricants or hydraulic oils.

However, it is also possible in principle to provide dialcohols having fewer than 5 or more than 14 carbon atoms. According to the desired properties of the ester oils, this may also be advantageous.

More preferably, the dialcohol is a terminal dialcohol. In terminal dialcohols, the alcohol groups are arranged at the ends of the carbon chain of the alcohol. It is thus possible to form, together with monocarboxylic acids, ester oils which are particularly suitable as lubricants and hydraulic oils. In addition, the production of terminal dialcohols from renewable raw materials, for example vegetable oils, is possible without any problem, which is to the benefit of economic viability.

The dialcohol advantageously comprises one or more representatives from the group of 1,6-hexanediol (HO—C6H12—OH), 1,7-heptanediol (HO—C7H14—OH), 1,8-octanediol (HO—C8H16—OH) 1,9-nonanediol (HO—C9H18—OH) 1,10-decanediol (HO—C10H20—OH), 1,12-dodecanediol (HO—C12H24—OH), 1,13-tridecanediol (HO—C13H26—OH) and/or isomers thereof. Isomers mean especially compounds which have the same empirical formula but differ with regard to linkage and/or spatial arrangement of the individual atoms. With such dialcohols having 6, 7, 8, 9, 10, 12 or 13 carbon atoms, it is possible to form a multitude of ester oils which can be prepared economically from renewable raw materials and which are particularly suitable for lubricants and hydraulic oils.

In principle, however, it is also conceivable to use alcohols having three or even more hydroxyl groups. It is also possible to use other representatives of dialcohols than those above, these having, for example, fewer than 5 carbon atoms or more than 14 carbon atoms.

It may also be advantageous to provide a mixture of at least two different dialcohols. In this case, it is firstly possible to control the properties of the ester oils even more precisely, and secondly to further optimize the preparation process in terms of economic viability. Advantageously, the at least two different dialcohols originate from renewable raw materials.

In a further preferred variant, the at least one monocarboxylic acid originates from renewable raw materials. It is thus possible to prepare the inventive ester oils, for example, in a particularly economically viable manner in few process steps via fatty acids from vegetable oils. The fatty acids can be used directly without any need to convert them to alcohols or other derivatives in additional reaction steps. Since at least two moles of monocarboxylic acid can be converted per mole of dialcohol in each case, it is additionally possible through the use of monocarboxylic acids from renewable raw materials to achieve a relatively high proportion of renewable raw materials in the reaction product or the ester oil. This also simplifies compliance with current environmental regulations or ecolabels.

More preferably, both the dialcohol and the monocarboxylic acid originate from renewable raw materials. It is thus possible to further improve the aforementioned advantages.

However, it is also possible in principle to use monocarboxylic acids from fossil raw materials, if this appears appropriate to the purpose.

The at least one monocarboxylic acid is preferably saturated. In other words, there are preferably only single bonds between the carbon atoms of the at least one monocarboxylic acid. It is thus possible to improve especially the oxidation resistance and stability of the ester oil.

In a particularly advantageous variant, both the dialcohol and the at least one monocarboxylic acid are saturated. This greatly improves the oxidation resistance and aging resistance.

Advantageously, the at least one monocarboxylic acid is unbranched. Thus, the at least one monocarboxylic acid advantageously has an unbranched carbon chain, which is especially linear. This has been found to be advantageous for a multitude of applications, especially with regard to an optimal viscosity of the ester oil. This is the case especially for a combination with unbranched dialcohols.

In another advantageous variant, the at least one monocarboxylic acid, however, may also be branched.

Especially suitable are monocarboxylic acids which are singly or multiply methyl-branched. The monocarboxylic acid more preferably has a terminal iso branch. The use of such branched monocarboxylic acids can, under some circumstances, lower the pour point and increase the flashpoint, which may be advantageous for specific applications. In addition, ester oils with branched monocarboxylic acids, under some circumstances, have higher seal compatibilities.

Branched monocarboxylic acids have been found to be advantageous especially in combination with unbranched dialcohols and especially unbranched dialcohols. Branched dialcohols, especially branched dialcohols are advantageously used in combination with unbranched monocarboxylic acids.

In principle, however, it is also possible to use branched monocarboxylic acids in combination with branched dialcohols.

More particularly, the at least one monocarboxylic acid has 6-18 carbon atoms, preferably 9-16 carbon atoms. Such monocarboxylic acids can firstly be obtained economically from renewable raw materials, for example in the form of fatty acids from vegetable oils, and secondly enable the production of a wide range of ester oils which are particularly suitable as lubricants or hydraulic oils. This is the case especially in combination with dialcohols having 5-14 carbon atoms.

In principle, however, it is also possible to provide monocarboxylic acids having fewer than 6 or more than 18 carbon atoms. According to the desired properties of the ester oils, this may also be advantageous under some circumstances.

Advantageously, the at least one monocarboxylic acid is a fatty acid, and the at least one monocarboxylic acid especially comprises one or more representatives from the group of caprylic acid (C7H15—COOH; also referred to as octanoic acid), pelargonic acid (C8H17—COOH; also referred to as nonanoic acid), capric acid (C9H19—COOH; also referred to as decanoic acid), undecanoic acid (C10H21—COOH), lauric acid (C11H23—COOH; also referred to as dodecanoic acid), tridecanoic acid (C12H25—COOH), myristic acid (C13H27—COOH; also referred to as tetradecanoic acid), hexanedecanoic acid (C15H31—COOH, also referred to as palmitic acid), octanedecanoic acid (C17H35—COOH, also referred to as stearic acid) and/or isomers thereof. Such monocarboxylic acids are especially obtainable economically from renewable raw materials and are particularly suitable for the inventive ester oils.

The monocarboxylic acids mentioned in the last paragraph have been found to be advantageous particularly in combination with polyalcohols, especially dialcohols, having 5-14 carbon atoms. Particularly suitable combinations are those with one or more representatives from the group of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,13-tridecanediol and/or isomers thereof.

However, it is also possible in principle to use other dialcohols and/or combinations with other polycarboxylic acids.

In a further optional variant, the monocarboxylic acid is a cyclic monocarboxylic acid, especially a saturated cyclic monocarboxylic acid. A suitable example is CH3—(CH2)x—C6H10—(CH2)y—COOH, where x+y=10, more preferably 9-(2′-n-propylcyclohexyl)nonanoic acid [CH3—(CH2)2—C6H10—(CH2)8—COOH]. This can be obtained directly from linseed oil, which is present in the seeds of flax, by alkaline isomerization [on this subject, see Beal et al.; JAOCS 42, 1115-1119 (1965)].

More preferably, the dialcohol is a dialcohol having 12 carbon atoms, especially 1,12-dodecanediol, and the at least one monocarboxylic acid is a monocarboxylic acid having 13 carbon atoms, more preferably 1-tridecanoic acid and/or isotridecanoic acid. Such ester oils have been found to be particularly advantageous for lubricants and hydraulic oils in terms of the preparation and the properties.

In both aspects of the invention, the inventive ester oil, based on the carbon content, is formed from renewable raw materials preferably to an extent of at least 25 mol %, further preferably at least 50 mol %, even further preferably at least 60 mol %, especially preferably at least 70 mol %. In a very particularly preferred embodiment, the inventive ester oil is formed exclusively from renewable raw materials apart from unavoidable impurities.

It is thus possible to produce high-performance ester oils particularly suitable for lubricants and hydraulic fluids in an economic manner, these additionally also being able to satisfy current and future environmental regulations.

In principle, a lower proportion than 25% of renewable raw materials may also be present. However, the aforementioned advantages are absent under some circumstances.

As has been found, a molecular weight of the esterification product is advantageously at least 400 g/mol, especially at least 550 g/mol. This is true of both aspects of the invention. It has been found that such ester oils are of particularly good suitability especially as lubricants and hydraulic oils. The reason for this might be that the substance properties of particular relevance for lubricants and hydraulic oils (viscosity, viscosity index, flashpoint or pour point) in the case of such ester oils are all within a practicable to ideal range.

However, ester oils having a lower molecular weight than 500 g/mol are also possible. This, however, may be disadvantageous for particular applications of the ester oils.

The esterification product preferably has at least 30 carbon atoms and/or at most 50 carbon atoms. As has been found, esterification products having at least 30 carbon atoms result in sufficiently high viscosity values, such that the corresponding ester oils are especially suitable for hydraulic oil and/or lubricant. The necessity of addition of additives to improve the viscosity level can be significantly reduced as a result, or becomes entirely unnecessary. In addition, it has been found that ester oils comprising esterification products having at most 50 carbon atoms are particularly suitable with regard to flow properties for hydraulic oils and/or lubricants. Particularly advantageously, the ester oils comprise esterification products having at least 30 carbon atoms and/or at most 50 carbon atoms. It is thus unexpectedly possible to simultaneously lower the pour points and increase the viscosity level.

In principle, the ester oils may also comprise esterification products which have fewer than 30 carbon atoms and/or more than 50 carbon atoms. This may even be appropriate for specific applications.

The inventive ester oils can particularly be used as lubricant and/or hydraulic oil. This is true both of ester oils according to the first aspect and of ester oils according to the second aspect.

Lubricants and/or hydraulic oils comprising an inventive ester oil preferably have a proportion of ester oil of at least 50% by weight, preferably at least 75% by weight, further preferably at least 90% by weight, even more preferably at least 93% by weight, still further preferably at least 96% by weight, measured by the total weight of the lubricant.

Smaller proportions of ester oil are also possible, but the lubricant or hydraulic fluid then under some circumstances no longer have the aforementioned advantageous properties.

In a preferred variant, the lubricant and/or the hydraulic fluid comprises additives for improving the properties.

Advantageously, the additives used are antioxidants, antiwear additives, metal deactivators, corrosion inhibitors and/or antifoams.

Advantageous antioxidants are especially aminic anti-oxidants and/or phenolic antioxidants. Suitable aminic antioxidants are alkylated diphenylamines (alkylated DPA) and/or N-phenyl-alpha-naphthylamine (PANA). A proportion of the aminic antioxidants is especially 0.01-3% by weight, more preferably 0.1-0.5% by weight.

Advantageous phenolic antioxidants are especially butylhydroxytoluene (BHT), 2,6-di-tert-butylphenol (2,6-DTBP) and/or derivatives of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Particularly suitable derivatives are octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and pentaerythrityl tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Likewise advantageous are, for example, 6,6′-di-tert-butyl-2,2′-methylenedi-p-cresol [CAS #: 119-47-1] and 4,4′-methylenebis-2,6-di-tert-butylphenol [CAS #: 118-82-1]. A proportion of the phenolic antioxidants is especially 0.01-5% by weight, more preferably 0.3-0.7% by weight.

More particularly, the lubricant and/or the hydraulic fluid comprise both aminic antioxidants and phenolic antioxidants.

Advantageously, ashless antiwear additives are used. Antiwear additives such as zinc dithiophosphates, for example, are therefore preferably not used. Suitable antiwear additives are especially amine phosphates, alkylated phosphates, for example tricresyl phosphate, triphenyl phosphorothionate and/or thionated esters. A proportion of the antiwear additives is advantageously 0.01-3% by weight, especially 0.6-1.0% by weight.

Advantageous metal deactivators have been found to be especially benzotriazole, tolutriazole and corresponding Mannich bases and/or derivatives of 2,5-dimercapto-1,3,4-thiadiazole. A proportion of the metal deactivators is advantageously 0.01-1% by weight, preferably 0.02-0.1% by weight.

Suitable corrosion inhibitors are, for example, alkylated succinic acid and/or derivatives thereof, for example monoesters, monoamides and/or amine phosphates.

The proportion of corrosion inhibitors is especially 0.01-3% by weight, preferably 0.1-0.4% by weight.

Suitable antifoams are especially alkyl polyacrylates, methacrylate derivatives and/or polydimethylsiloxane (PDMS). An advantageous proportion is 0.001-0.1% by weight, preferably 0.01-0.03% by weight.

The aforementioned antioxidants, antiwear additives, metal deactivators, corrosion inhibitors and/or anti-foams are, in particular, chemically compatible with the inventive ester oils. With the proportions specified, optimal effects are additionally achieved, without impairing the performance of the lubricants and/or hydraulic fluids. In principle, however, it is also possible to use additional and/or other additives. It is also possible to dispense with individual additives or all of the additives mentioned.

The monocarboxylic acids, polycarboxylic acids, monoalcohols and/or dialcohols used for preparation for the ester oils are preferably prepared from fatty acids from renewable raw materials. Especially suitable are palm oil and/or fatty acids such as oleic acid (C18:1; 9Z; ω-9), linoleic acid (C18:2; 9Z, 12Z; ω-6), gadoleic acid (C20:1; 11Z, ω-9), erucic acid (C22:1, 13Z; ω-9), petroselinic acid (C18:1; 6Z; ω-6), arachidonic acid (C20:4; 5Z, 8Z, 11Z, 14Z; ω-6) and/or generally ω-6-fatty acids. The number which follows the letter “C” after the name of the fatty acid in each case indicates the number of carbon atoms. Separated by a colon, there follows the number of double bonds in the fatty acid and details of position and configuration (Z, E) of the double bonds in the carbon chain. Likewise listed is the ω type of the fatty acid or the position of the first double bond based on the last carbon atom furthest removed from the carboxyl group (“ω”) in the carbon chain.

Especially suitable for preparation of the monocarboxylic acids, polycarboxylic acids, monoalcohols and/or dialcohols used for the ester oils are also hydroxy fatty acids, especially ricinoleic acid (C18:1; 9Z; 12R; 12-hydroxy; ω-9), lesquerolic acid (C20:1; Z11; 14-hydroxy) and/or vernolic acid (C18:1; 9Z; 13-epoxy; ω-9).

Such raw material sources allow, more particularly, economically viable production of ester oils for lubricants and hydraulic oils. The person skilled in the art is aware of a multitude of vegetable oils and/or animal fats from which the aforementioned fatty acids can be obtained.

In principle, however, it is also possible to resort to other sources if this appears more advantageous.

The detailed description which follows and the entirety of the claims give rise to further advantageous embodiments and feature combinations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawing show:

FIG. 1 a diagram which shows the coefficients of friction (f) as a function of time or standard force in a friction-wear test (to SRV III; and standard ASTM D 7421-08) for three selected ester oils compared to DITA and TMP;

FIG. 2a,b four diagrams which show the coefficients of friction (f), the standard force (FN) and stroke (dx) in the friction-wear test on which FIG. 1 is based with diisotridecyl adipate as a function of time;

FIG. 3a,b four diagrams which show the coefficients of friction (f), the standard force (FN) and stroke (dx) in the friction-wear test on which FIG. 1 is based with di(isotridecyl) dodecanedioate (C12D13) as a function of time;

FIG. 4a,b four diagrams which show the coefficients of friction (f), the standard force (FN) and stroke (dx) in the friction-wear test on which FIG. 1 is based with trimethylolpropane ester (TMP-C8/C10) as a function of time.

 WAYS OF PERFORMING THE INVENTION A) Carboxylic Acids Fatty Acids

Fatty acids, such as oleic acid, linoleic acid, gadoleic acid, erucic acid, petroselinic acid, arachidonic acid, or ω-6-fatty acids in general, can be obtained, for example, in a manner known per se by means of alkaline hydrolysis from the corresponding triacyl glycerides. This involves boiling the corresponding fats or oils with bases. The salts obtained can then be neutralized with acids, which gives free fatty acids or mixtures of free fatty acids. Separation of the different fatty acids in the mixtures is effected, for example, by a distillative separation process.

Oleic acid can be obtained, for example, from olive oil, peanut oil, avocado oil, goose fat, palm oil, pork fat, sesame oil, mutton tallow, beef tallow and sunflower oil. Linoleic acid is obtainable, for example, from safflower oil, sunflower oil, soya oil, corn kernel oil and olive oil. Gadoleic acid is present in jojoba oil, while erucic acid occurs in various rapeseed oil varieties and sea kale species. In addition, petroselinic acid can be obtained from coriander oil, and arachidonic acid from animal fats or fish oil.

Hydroxy Fatty Acids

Ricinoleic acid can be obtained, for example, by hydrolysis of castor oil, in which the substance occurs in the form of triglycerides. Lesquerolic acid is obtainable especially from the oil from Lesquerella of fendleri seeds, while vernolic acid is obtainable from the seeds of Vernonia galamensis, a plant from the sunflower family, by extraction.

Adipic Acid (C6)

Adipic acid [Chemical Abstracts number (CAS #): 124-04-09; HOOC—(CH2)4—COOH; molecular weight (Mw)=146.14] can be obtained by petrochemical means from cyclohexane by double oxidation, for example with nitric acid, or from cyclohexanol [K. Saro et al., “A green route to adipic acid: direct oxidation of cyclohexene with 30 percent hydrogen peroxide”, Science, Vol. 281, p. 1646-1647 (1998)]. Another possibility is oxidation of cyclohexene by means of H2O2 (30%) using a phase transfer catalyst (quaternary ammonium hydrosulfate or Na2WO2+[CH3(n-C8H17)3N]HSO4).

Adipic acid from renewable raw materials can be obtained, for example, from xylose derivatives (C5 sugars), by decarbonylation of furfuryl alcohol (furfural, C5H4O2). It can likewise be obtained from glucose (C6 sugar), in the form of sorbitol, or from D-glucose [K. M. Drahts et al., J. Am. Chem. Soc. 1994, Vol. 116, p. 399-400] via cis,cis-muconic acid [CAS #: 1119-72-81] and 5-hydroxymethylfurfural (5-HMF) by thermal decomposition from sugar. In addition, it is possible to obtain adipic acid via an oxidative cleavage of an ω-6-fatty acid, for example gamma-linolenic acid [C18H30O2; Mw=278.43].

The oxidative cleavage of gamma-linolenic acid as ω-6-fatty acid gives 2 mol of adipic acid as well as 2 mol of malonic acid, which constitutes an effective yield.

It is also possible to prepare adipic acid by oxidative cleavage of arachidonic acid [CAS #: 506-32-11; C20H32O2; Mw=304.46].

The latter can in turn be prepared via mono- and diasaccharides, hemicellulose (wood cooking), petroselinic acid and/or 1,4-butanediol. Likewise possible is enzymatic synthesis from ammonium adipate with genetically modified microorganisms. In this regard, reference is made to U.S. Pat. No. 5,629,190.

Petroselinic acid [CAS #: 593-39-51, C18H34O2; Mw=282.46], an isomer of oleic acid, as the cis or trans stereoisomer, has an unsaturated bond at C6, which can be oxidatively cleaved in order to directly obtain adipic acid, additionally giving lauric acid, i.e. n-dodecanoic acid (a C12-monocarboxylic acid; Mw=200.31). The latter can then be reduced, for example with lithium aluminum hydride, to 1-dodecanol (lauryl alcohol; C12H26O; Mw=186.33). Petroselinic acid itself is present in coriander seeds, but also in fennel.

Branched Adipic Acid Derivatives (C9)

3-Methyladipic acid [CAS #: 3058-01-3; C7H12O4; Mw=160.2], a singly methyl-branched adipic acid, can be obtained from cresol via methylcyclohexanone and is also commercially available (for example from Sigma-Aldrich).

2,2,3-Trimethyladipic acid [CAS #: 28472-18-6; C9H16O4; Mw=188.2], 2,2,4-trimethyladipic acid [CAS #: 3586-39-8; C9H16O4; Mw=188.2] and 2,4,4-trimethyladipic acid [CAS #: 3937-59-5; C9H16O4; Mw=188.2] are multiply methyl-branched derivatives of adipic acid which are likewise commercially available.

Azelaic Acid (C9)

Azelaic acid [CAS #: 123-99-9; C9H16O4; with Mw=188.22] is obtainable by an oxidative cleavage at the respective double bond of oleic acid, i.e. cis-9-octadecenoic acid [CAS #: 112-80-1; C18:1; cis-9] by means of ozone (ozonolysis) at approx. 100° C. or the reagents H2O2, NaOCl (with ruthenium catalyst), hot nitric acid, KMnO4 or chromic acid. A by-product additionally obtained is pelargonic acid [CAS #: 112-05-0; C9H18O2; with Mw=158.24; also called nonanoic acid], a monocarboxylic acid. In this regard, reference is also made to U.S. Pat. No. 2,823,113 and U.S. Pat. No. 5,336,7931.

The same applies mutatis mutandis in the case of use of elaidic acid, i.e. trans-9-octadecenoic acid [CAS #: 112-79-8; C18H34O2], which corresponds to the trans isomer of oleic acid.

The pelargonic acid obtained can be reduced to 1-nonanol [CAS #: 143-08-61, Mw=144.29] as a C9 alcohol, in order to use it as a renewable alcohol in a dicarboxylic ester.

Azelaic acid, however, is also obtainable in the same way from gadoleic acid, i.e. eicosenoic acid [CAS #: 267634-41-0; C20:1; (−9; Mw=310.51] by oxidative cleavage. A by-product formed is undecanoic acid [CAS #: 112-37-8; Mw=186.30] as a C1l-monocarboxylic acid, which can be reduced to n-undecanol [CAS #: 112-45-2; C11H24O; Mw=172.30].

Brassylic Acid (C13)

Brassylic acid is obtainable via cis-erucic acid, i.e. cis-13-docosenoic acid [CAS #: 112-86-7; C22:1; co-13; Mw=338.56] or the trans isomer, trans-13-docosenoic acid, present in rapeseed oil, mustard oil or Abyssinian sea kale. By oxidative cleavage (in the same way as described for azelaic acid), pelargonic acid is formed as the monocarboxylic acid, and brassylic acid, i.e. tridecanedioic acid [CAS #: 505-52-2; C13H24O4; Mw=244.3], as the saturated C13 dicarboxylic acid.

Suberic Acid (C8)

Suberic acid can be obtained by petrochemical means, by ozonolysis of cyclooctene. On the basis of renewable raw materials, it can be obtained essentially from cork and potato peelings.

Cork powder can be cleaved to suberic acid by oxidation with HNO3. Likewise possible is the oxidative cleavage of ricinoleic acid, palm oil and oleic acid, in which not only azelaic acid but also suberic acid is formed [see, for example, R. G. Kadesch; J. Am. Oil Chemists' Soc. Vol. 56, p. 845A-849A (1979) and references mentioned therein].

Specifically, suberic acid, i.e. octanedioic acid [CAS #: 505-48-6; C8H14O4; Mw=174.19], for example in the case of a suitable reaction regime, is obtainable by an oxidative cleavage at the double bond of ricinoleic acid [CAS #: 141-22-0, 8040-35-5; 17026-54-9; 25607-48-1; 45260-83-1; C18H34O3; Mw=298.46], a 12-hydroxy-9-octadecenoic acid (C18:1) from castor oil [J. W. Hill et al., Organic Syntheses, Coll. Vol. 2, p. (1943) and Vol. 56, p. 4 (1933); M. J. Diamond et al., J. Am. Oil Chemists' Soc., Vol. 42, p. 882-884 (1965); R. G. Kadesch; J. Am. Oil Chemists' Soc. Vol. 31, p. 568-573 (1954)].

By an alkaline cleavage with NaOH at 180-270° C., sebacic acid sodium salt and 2-octanol, i.e. capryl alcohol [C8H18O; Mw=130.22], are obtained.

Dodecanedioic Acid (C12)

The seed of Lesquerella contains approx. 55-60% of the hydroxy fatty acid 14-hydroxy-cis-11-eicosanoic acid [CAS #: 4103-20-2; C20H38O3; Mw=326.51], which can likewise be cleaved oxidatively in NaOH at 180-250° C. to dodecanedioic acid [C12H22O4] and 2-octanol, and also 12-hydroxydodecanoic acid [CAS #: 505-95-31] and 2-octanone [CAS #: 111-13-7].

B) Preparation of Monoalcohols 2-Octanol, 1-nonanol, n-undecanol and 1-dodecanol

Possible sources and processes for preparing 2-octanol [C8H18O; Mw=130.22], 1-nonanol [CAS #: 143-08-61, C9H20O; Mw=144.29], n-undecanol [CAS #: 112-45-2; C11H24O; Mw=172.30], 1-dodecanol (lauryl alcohol; C12H26O; Mw=186.33) have already been mentioned above in the context of the preparation of dicarboxylic acids from renewable raw materials.

Isononanol

3,5,5-Trimethylhexyl alcohol, i.e. isononyl alcohol [CAS #: 3452-97-9; C9H20O; Mw=144.3], a highly branched isomer of nonanol, is sold by Exxon and Kyowa Hakko Kogyo Co. Ltd.

1-Decanol

1-Decanol [CAS #: 112-30-1; C10H22O; Mw=158.3] is obtainable, for example, by hydrogenation of capric acid (C9H19COOH). Capric acid itself occurs, for example, bound in triglycerides in vegetable oils, and is also present in palm oil, coconut oil, and in goats' milk fat.

Isodecanol

Isodecanol [CAS #: 25399-17-7; C10H22O; Mw=158.3] is obtainable, for example, under the “EXXAL” trade name via Exxon. In addition, mixtures with C9-C11 alcohols rich in C10 alcohols are also supplied commercially [CAS #: 93821-11-5 or 68526-85-2].

1-Tridecanol

1-Tridecanol, i.e. n-tridecanol [CAS #: 112-70-9; C13H28O; Mw=200.4], is commercially available with a purity of >98% (for example from Sigma-Aldrich). However, various mixtures comprising 1-tridecanol are commercially available, for example a mixture of 1-tridecanol with 1-dodecanol [CAS #: 90583-91-8] from BASF, or a mixture of C10-C17 alcohols also comprising the C1-3 alcohols under the “Neodol 25” name from Shell. Another possible preparation is the reduction of tridecanoic acid [CAS #: 638-53-9; C13H26O2; Mw=214.3], which is found in some vegetable oils, for example in the seeds of the Australian plant Stackhousia tryonii).

Isotridecanol

Isotridecanol, i.e. 11-methyldodecanol [CAS #: 27458-92-0; C13H28O; Mw=200.4] is obtainable on the basis of propylene tetramer [CAS #: 6842-15-5] or tetrapropylene/1-dodecene [CAS #: 112-41-4] and via basic oxidation at 250-300° C. Isotridecanol is sold commercially, for example by Exxon under the EXXAL13 product name.

1-Tetradecanol

1-Tetradecanol or myristyl alcohol [CAS #: 112-72-1; C14H30O; Mw=214.4], also defined in a technical commercial context as a mixture of straight-chain and 100% linear C12-C16 alcohols with a content of >95% of C14 alcohols, can be obtained by reduction of myristic acid C14:0 [CAS #: 544-63-81], which is present in coconut oil to an extent of approx. 15-21% and in palm kernel oil to an extent of approx. 14-18%.

General Fatty Alcohols

It is common knowledge that fatty alcohols can be obtained directly from vegetable raw materials. Fatty alcohols having 8 carbon atoms (C8) to 18 carbon atoms (C18), for example 1-octanol [CAS #: 111-87-5; C8H18O], decanol, dodecanol (lauryl alcohol); tetradecanol (myristyl alcohol), hexadecanol [CAS #: 36653-82-4; C18H34O; Mw=242.44; also called cetyl alcohol] and/or octadecanol [CAS #: 112-92-5; C18H38O; Mw=270.5; also called stearyl alcohol], can be prepared, for example, by reduction of corresponding esters with sodium (Bouveault-Blanc reaction). It is also possible to prepare fatty alcohols by hydrogenation over copper or copper/cadmium catalysts. Frequently, fatty alcohols are nowadays produced by petrochemical means from mineral oil and are commercially available as such. Fatty alcohols can be prepared from renewable raw materials especially by hydrogenation of fatty acids from vegetable oils. The fatty acids, for example, are reduced with lithium aluminum hydride in a manner known per se to the corresponding fatty alcohols.

C) Preparation of Polyols Neopentyl Glycol

Neopentyl glycol, i.e. 2,2-dimethyl-1,3-propanediol [CAS #: 126-30-7; C5H12O2; Mw=104.2], is commercially available or can be prepared via hydrogenation of the aldol addition product of isobutyraldehyde and formaldehyde (in this regard, see WO 2008/000650 A1).

1,6-Hexanediol

1,6-Hexanediol [CAS #: 629-11-8; C6H14O2; Mw=118.2] can be obtained, for example, by reduction of adipic acid with lithium aluminum hydride, or esters thereof with elemental sodium. It is thus possible to prepare 1,6-hexanediol from renewable raw materials.

It is also possible to prepare 1,6-hexanediol from glucitol [CAS #: 50-70-4; C6H14O6; Mw=182.2; also called sorbitol]. This involves reducing glucitol at positions 2, 3, 4 and 5 with elimination of the hydroxyl groups. Glucitol itself is obtainable in a manner known per se by hydrogenation of glucose from cereals, beets or cane sugar.

2,2,4-Trimethyl-1,3-pentanediol

2,2,4-Trimethyl-1,3-pentanediol [CAS #: 144-19-4; C8H18O2; Mw=146.2] is commercially available (Alfa Aesar, Hangzhou Dayang Chemical Co., Ltd.).

2-Butyl-2-ethyl-1,3-propanediol

2-Butyl-2-ethyl-1,3-propanediol [CAS #: 115-84-4; C9H20O2; Mw 160.3] is likewise commercially available (Sigma-Aldrich; Jinan Haohua Industry Co., Ltd.).

Further Dialcohols

It is possible to form further dialcohols from the aforementioned dicarboxylic acids by reduction, for example with lithium aluminum hydride, these dialcohols being usable for inventive ester oils.

D) Refining

The mono- and dicarboxylic acids and alcohols obtained, for example, from the oxidative cleavage are separated from one another by processes known per se to those skilled in the art with exploitation of different substance properties, for example melting point, solubilities (extraction, hot water), boiling temperatures (selective distillation) and/or acid cleavage (H2SO4), in order to obtain sufficiently pure substances.

E) Preparation of Diesters on the Basis of Dicarboxylic Esters

Dicarboxylic esters can be prepared in a manner known per se by reaction of dicarboxylic acids with monoalcohols with elimination of water. The esterification can especially be acid-catalyzed (Fischer esterification) and is well known to those skilled in the art. For the preparation of dicarboxylic esters, more particularly, 2 mol of monoalcohols are reacted with 1 mol of dicarboxylic acid.

The diesters listed in the table which follows have been found to be particularly advantageous in the practical test for hydraulic oils. All diesters can be produced to an extent of 100% from renewable raw materials. In the last column, the maximum proportion of renewable raw materials formed from the dicarboxylic acid (Ac) and from the monoalcohols (Al) in the diester is reported in each case.

Dicarboxylic acid Proportion Monoalcohol Dicarboxylic acid of RRM Adipic acid Isodecanol Ac: 26.3% Al: 73.7% Adipic acid 1-Tridecanol Ac: 18.8% Al: 81.2% Adipic acid Isotridecanol Ac: 18.8% Al: 81.2% Adipic acid 1-Tetradecanol Ac: 18% Al: 82% Azelaic acid 1-Tridecanol Ac: 26% Al: 74% Dodecanedioic acid 1-Nonanol Ac: 40.0% Al: 60.0% Dodecanedioic acid Isodecanol Ac: 37.5% Al: 62.5% Dodecanedioic acid Isotridecanol Ac: 31.6% Al: 68.4% Dodecanedioic acid 1-Tridecanol Ac: 31.6% Al: 68.4%

G) Preparation of Ester Oils on the Basis of Diol Esters

Dialcohol esters or diol esters can be obtained by reaction of dialcohols with monocarboxylic acids. For the preparation of diol esters, more particularly, 2 mol of monocarboxylic acids are reacted with 1 mol of diol.

The diesters listed in the table below have been found to be particularly advantageous in the practical test for hydraulic oils. The diol esters can also be produced to an extent of 100% from renewable raw materials. In the last column, the maximum proportion of renewable raw materials formed from the diol (Al) and from the monocarboxylic acids (Ac) in the diol ester is reported in each case.

Diol/Mono- carboxylic Proportion acid Diol ester of RRM 1,6-Hexanediol Isodecanoic acid Ac: 23.1% Al: 76.9% 1,6-Hexanediol 1-Tridecanoic acid Ac: 18.8% Al: 81.2% 1,6-Hexanediol Isotridecanoic acid Ac: 18.8% Al: 81.2% 1,6-Hexanediol Tetradecanoic acid Ac: 18% Al: 82% 1,9-Nonanediol 1-Tridecanoic acid Ac: 26% Al: 74% 1,12-Dodecane- diol Pelargonic acid (nonanoic acid) Ac: 40.0% Al: 60.0% 1,12-Dodecane- diol Isodecanoic acid Ac: 37.5% Al: 62.5% 1,12-Dodecane- diol Isotridecanoic acid Ac: 31.6% Al: 68.4% 1,12-Dodecane- diol 1-Tridecanoic acid Ac: 31.6% Al: 68.4%

The above-described diesters are merely examples which can be modified in the context of the invention.

In the case of the aforementioned diesters based on adipic acid, it is also possible to replace the adipic acid with one of the following branched derivatives: 3-methyladipic acid [CAS #: 3058-01-3, C7H12O4; Mw=160.2], 2,2,3-trimethyladipic acid [CAS #: 28472-18-6; C9H16O4; Mw=188.2], 2,2,4-trimethyladipic acid [CAS #: 3586-39-8; C9H16O4; Mw=188.2] and/or 2,4,4-trimethyladipic acid [CAS #: 3937-59-5; C9H16O4; Mw=188.2]. It is thus possible to lower the pour points and slightly increase the viscosity level compared to the unbranched variants.

In the case of the above-described diol esters, for example, 1,6-hexanediol can also be prepared by branched diols from the group of neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol and/or 2-butyl-2-ethyl-1,3-propanediol.

H) Hydraulic Oils

Inventive hydraulic oils advantageously have at least 93% by weight of a base oil. For example, a hydraulic oil has the composition described in Table 1 below.

TABLE 1 Component Proportion [% by weight] Aminic antioxidants 0.30 Phenolic antioxidants 0.50 Antiwear additives 0.80 Metal deactivators 0.04 Corrosion inhibitors 0.20 Antifoams 0.02 Ester oil (dicarboxylic 98.14 esters and/or diol esters)

L) Selected Diesters/Viscometric Properties

Table 2 below shows various viscometric properties of selected diesters. As can be inferred from the table, particularly the diesters having more than 30 carbon atoms have relatively high viscosity levels (cf. Θ40° C. values), which is particularly advantageous in the case of use as a hydraulic oil or lubricant. The values in the OECD 301 B/F column indicate the biodegradability according to the OECD test methods known per se. The UBA # column indicates the numbers assigned by the German Federal Environment Agency.

TABLE 2 Flash- NOACK Pour η40° C. η100° C. OECD 301 Base oil point [° C.] [%] VI point [° C.] [mm2/s] [mm2/s] UBA # B/F [%] Adipates Diisodecyl adipate (C26) 235 15.5 148 −60 14.0 3.10 82 Di-n-tridecyl adipate (C32) 5278 [16958-92-2] Diisotridecyl adipate (C32) 227 8-10 139 −51 27.0 5.4 2362 92 [26401-35-4] Ditetradecyl adipate (C34) 75 34.3 5.1 [26720-19-4] Azelates Didecyl azelate (C29) [2131-27-3] Diisodecyl azelate (C29) 230 9.8 151 −65 18.1 4.3 3756 [28472-97-1] Diundecyl azelate (C31) Didodecyl azelate (C33) [26719-99-3] Bis(2-hexyldecyl) azelate 278 160 −64 33.0 6.60 (C41) Di(isotridecyl) azelate 258 4.0 124 −39 42.4 6.82 [27251-77-0] Ditridecyl azelate (C35) 243 145 −55 33.8 6.4 [26719-40-4] Dodecanedioates Dioctyl dodecanedioate [42233-97-6] Diisooctyl dodecanedioate [85392-86-5] Di(iso-C9) dodecanedioate 6.0 184 −25 23.2 5.28 4190 [63003-34-9] Di(C9) dodecanedioate 245 5.0 189 24.8 5.6 Di(isodecyl) dodecanedioate 266 3.5 161 −46 25.7 5.58 [63003-35-0] Di(isodecyl) dodecanedioate 4.3 162 −41 23.4 5.2 93 Ditridecyl dodecanedioate (C38)[27742-10-5] Di(isotridecyl) 277 5.7 158 −57 42.0 7.5 4203 76 dodecanedioate (C38) [84731-63-5] Dicetyl dodecanedioate [42234-04-8] Diol esters Dodecanediol dipelargonate 7.4 182 −38 25.25 5.58 Hexanediol diisocaprilate 17.3 119 <−70 17.41 3.79 (C26) Hexanediol diisomyristate (C34)

J) Comparative Tests with Selected Diesters

The unadditized ester base oils trimethylolpropane ester (TMP-C8/C10), diisotridecyl adipate (DITA), di(isotridecyl)dodecanedioate (C12D13, three samples), di(isotridecyl)decanedioate (C10D13, three samples) and di(isotridecyl)nonanedioate (C9D13), and also the fully formulated hydraulic oil “PANOLIN HLP Synth” based on DITA (obtainable from Panolin, Switzerland) are compared in comparative tests hereinafter. In addition, the table also contains figures for a diester formed from a diol and two carboxylic acids, namely neopentyl glycol di(isostearate) (D5C18).

The lubricants used have the viscometric properties shown in Table 3. For the C12D13 esters and the C10D13 esters, three independently prepared samples were included in each case. For the C9D13 ester and for the D5C18 ester, one sample was analyzed in each case. The “CCS−25° C. [mPas]” and “CCS−20° C. [mPas]” columns each contain figures for the “Cold Crank Simulator” according to the standard ASTM D5293 at −25° C. and −20° C. The HTHS150° C. [mPas] column indicates what is called the “High-Temperature High-Shear Viscosity” (HTHS) at elevated temperature.

TABLE 3 Density Flash- NOACK Pour CCS−25° C. CCS−20° C. η40° C. η100° C. η150° C. HTHS150° C. Lubricant [g/cm3] point [° C.] [%] VI point [° C.] [mPas] [mPas] [mm2/s] [mm2/s] [mmVs] [mPas] C12D13 0.9051 276 2.4 158 −48 3210 1910 40.47 7.573 3.453 2700 (1st sample) C12D13 0.9020 277 4.3 147 −57 1700 42.0 7.5 (2nd sample) C12D13 0.904 261 2.9 156 −51 3230 41.2 7.6 (3rd sample) C10D13 2.7 172 −52 35.5 7.2 (4th sample) C10D13 250 4 150 −50 36.0 6.8 (5th sample) C10D13 3.4 149 35.7 6.7 (6th sample) C9D13 3.5 150 36.1 6.8 (7th sample) D5C18 280 2.0 146 −44 46.0 8.0 (8th sample) DITA 0.91 244 10.0 139 −60 2646 1455 25 5 TMP-C8/10 0.94 235 3.6 140 −30 853 221 22 4.5 PANOLIN 0.918 240 4.3 146 −57 4653 2780 47.0 8.10 HLP Synth

Table 4 contains ecotoxicological figures which are intended for guidance and are taken from safety data sheets. The “aquatic toxicity [mg/1]” column contains figures for the toxicity tests according to the known test methods to OECD 201, 202 and 203.

TABLE 4 Aquatic toxicity [mg/l] OECD 301 OECD OECD OECD UBA Lubricant B/F [%] 201 202 203 # C12D13 4203 (1st sample) C12D13 76/93 880   >1000 4203 (2nd sample) D5C18 85 >1000 >1000 >10 000 (8th sample) DITA 87 >1000 >100 2362 TMP-C8/10 64-88 140 600 >10 000 5371 PANOLIN 67-90 HLP Synth

In Table 3, a noticeable feature which is especially positive is that the NOACK vaporization (physical vaporization according to Noack, i.e. at 250° C. for 1 h) for the esters examined (samples 1-8) at 2.0-4.3%, even in the form of base oil, is at least much lower than for the ester base oils trimethylolpropane esters (TMP-C8/C10, 3.6%) and diisotridecyl adipate (DITA 10.0%). Trimethylolpropane esters (TMP-C8/C10) are commercially available from various suppliers and have been used for comparative purposes.

In addition, the NOACK values of the esters examined are also lower or identical compared to the NOACK value of the commercially available hydraulic oil “PANOLIN HLP Synth” (available from Panolin, Switzerland), which is a fully formulated hydraulic oil based on DITA. If the NOACK values of the esters examined are compared with “PANOLIN HLP Synth”, it can be expected that the NOACK value for a hydraulic oil fully formulated from an ester examined will be well below 2.0-4.3%. For the environment, this means less oil consumption, meaning introduction into the environment, and, for the user, lower refilling costs, which lowers the operating costs, and once again also benefits the environment in the form of resource protection.

Another advantage of the esters examined is the high flashpoint of up to 280° C., which is about 40° above that of “PANOLIN HLP Synth”. This is a distinct safety gain and additionally opens up, through suitable additization, the possibility of further raising the flashpoint into the range of low-flammability hydraulic fluids.

In viscometric terms, the C12D13 base oil is comparable to PANOLIN HLP Synth, i.e., for example, in the case of the kinematic viscosity at 40° C., without the addition of polymeric viscosity index improvers or thickeners. This results in better foaming characteristics, since the air bubbles are not stopped from rising by the macromolecules. Moreover, it can be assumed that the low-temperature viscosities of a polymer-free formulation or one with reduced polymer content based on C12D13 will be lower. This significantly improves lubrication at low temperatures, and lubrication film buildup is more rapid at all lubrication sites in the construction vehicle and the auxiliary equipment thereof, with lower pump output (energy efficiency). This lowers wear in the tribological systems (friction sites). This also applies to the other esters with shorter carboxylic acids examined.

The C12D13 base oil is classified by the committee for assessment of water-endangering substances at the German Federal Environment Agency under number 4203 in WGK 1 (slightly water-endangering, WGK=water endangerment class) which is a good prerequisite for the formulation of environmentally friendly hydraulic oils.

Overall, the esters examined exhibit higher viscosity indices, raised viscosity levels, increased flashpoints, and also lower NOACK vaporizations compared to diisotridecyl adipate (DITA).

FIG. 1 shows the results of vibration-frictional wear tests (SRV, model III) with the five unadditized ester base oils diisotridecyl adipate (DITA), trimethylolpropane ester (TMP-C8/C10), di(isotridecyl)nonanedioate (C9D13), di(isotridecyl)dodecanedioate (C12D13) and di(isotridecyl)decanedioate (C10D13).

The tests were conducted according to standard ASTM D7421-08 (fretting load) at a typical operating temperature for hydraulic oils of +80° C. The frequency was 50 Hz with a stroke of 1 mm (in positive x direction) and 2 mm (in negative x direction). The standard force was increased by 100 N every 2 minutes during the tests. It was found that the extension of the chain length of the dicarboxylic acid also improves the fretting load-bearing capacity of the base oil. For C9D13, C10D13 and C12D13, values of greater than P0mean=3938 MPa are achieved, since there is still no occurrence of adhesive failure at 2000 N or after 40 minutes.

The C9D13 diesters and C12D13 diesters exceed the fretting load limit for the trimethylolpropane ester (TMP-C8/C10) and, even as unadditized base oils, distinctly lower the mixed friction/boundary friction figure at high loads. What is remarkable in the case of these unadditized base oils formed from C9D13 diesters and C12D13 diesters is the fact that the mixed friction/boundary friction figure is virtually invariable with respect to the rise in load in the test to ASTM D7421-08.

FIG. 2a shows diagrams which illustrate the coefficient of friction (f) and the standard force (FN) (top) and the stroke (dx) and the standard force (FN) (bottom) of diisotridecyl adipate in the positive x direction as a function of time.

FIG. 2b correspondingly shows diagrams which describe the coefficient of friction (f) and the standard force (FN) (top) and also the stroke (dx) and the standard force (FN) (bottom) of diisotridecyl adipate in the negative x direction as a function of time.

FIGS. 3a,b show diagrams which describe the corresponding data for di(isotridecyl) dodecanedioate (C12D13), while FIGS. 4a,b analogously show the diagrams for trimethylolpropane esters (TMP-C8/C10).

What is particularly remarkable is the high fretting load of di(isotridecyl) dodecanedioate (C12D13) of >1700 N after a time of about 42 min (see, for example, FIG. 1). This is exceptionally high for a base oil, particularly at this low viscosity level, and is not achieved by fully formulated lubricants without additional measures.

The esters examined, di(isotridecyl)nonanedioate (C9D13), di(isotridecyl)dodecanedioate (C12D13) and di(isotridecyl)decanedioate (C10D13), are to be used for lubricants marked with an ecolabel, which, based on the carbon content, consist of renewable raw materials preferably to an extent of at least 25 mol %, further preferably at least 50 mol %, even further preferably at least 60 mol %, especially preferably at least 70 mol %. For a new class of biolubes, it is sufficient when at least 25 mol % of the overall formulation consists of renewable raw materials (RRM). Here too, the proportion is measured by means of radio carbon methods (ASTM D6866 or DIN EN 15440:2011-05).

This means that the ester C12D13 is already a biolube when only the acid component (dodecanedioic acid, RRM content of 31.6%) originates from renewable raw materials. C10D13 (RRM content of 27.8%) and C9D13 (RRM content of 25.7%) also fulfill this criterion. In contrast, C6D13 (DITA, RRM content of 18.75%) alone cannot be regarded as a biolube. A lubricant based on DITA fulfills this specification if it contains further esters from renewable raw materials in small amounts which compensate the proportion of renewable raw materials can become.

Claims

1-45. (canceled)

46. An ester oil, especially for production of a hydraulic oil and/or of a lubricant, comprising an esterification product of at least one unbranched monoalcohol with at least one polycarboxylic acid, characterized in that the unbranched monoalcohol and/or the polycarboxylic acid originates from renewable raw materials.

47. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid originates from renewable raw materials.

48. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid is saturated.

49. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid is unbranched.

50. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid is branched.

51. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid has 6-13 carbon atoms, preferably 8-13 carbon atoms.

52. The ester oil as claimed in claim 46, characterized in that the polycarboxylic acid comprises a dicarboxylic acid.

53. The ester oil as claimed in claim 52, characterized in that the dicarboxylic acid comprises adipic acid, trimethyladipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and/or brassylic acid.

54. The ester oil as claimed in claim 46, characterized in that the at least one monoalcohol originates from renewable raw materials.

55. The ester oil as claimed in claim 46, characterized in that the at least one monoalcohol is saturated.

56. The ester oil as claimed in claim 46, characterized in that the at least one monoalcohol has 6-24, preferably 8-16, carbon atoms, and the at least one monoalcohol more preferably has 9, 11, 12, 14 and/or 16 carbon atoms.

57. The ester oil as claimed in claim 46, characterized in that the at least one monoalcohol is a fatty alcohol.

58. The ester oil as claimed in claim 46, characterized in that the at least one monoalcohol comprises 1-nonanol, n-undecanol, 1-dodecanol, 1-tetradecanol and/or cetyl alcohol.

59. The ester oil as claimed in claim 46, characterized in that the esterification product, based on the carbon content, is formed to an extent of at least 50 mol %, preferably at least 60 mol %, even further preferably at least 70 mol %, from renewable raw materials.

60. The ester oil as claimed in claim 46, characterized in that a molecular weight of the esterification product is at least 400 g/mol, especially 550 g/mol.

61. The ester oil as claimed in claim 46, characterized in that the esterification product has at least 30 carbon atoms and/or at most 50 carbon atoms.

62. The use of an ester oil as claimed in claim 46 as a lubricant and/or hydraulic oil.

63. A lubricant and/or hydraulic oil comprising an ester oil as claimed in claim 46.

64. The lubricant and/or hydraulic oil as claimed in claim 63, characterized in that the proportion of ester oil is at least 50% by weight, preferably at least 75% by weight, further preferably at least 90% by weight, of the total weight of the lubricant and/or hydraulic oil.

65. The lubricant and/or hydraulic oil as claimed in claim 63, characterized in that additives are present, the additives present being antioxidants, antiwear additives, metal deactivators, corrosion inhibitors and/or antifoams.

66. A process for preparing an ester oil, especially for use in a hydraulic oil and/or a lubricant, by reacting an unbranched monoalcohol with a polycarboxylic acid to give an ester oil, characterized in that the unbranched monoalcohol and/or the polycarboxylic acid originate from renewable raw materials.

67. The process as claimed in claim 66, characterized in that the alcohols and/or carboxylic acids are prepared from fatty acids from renewable raw materials.

68. An ester oil, especially for production of a hydraulic oil and/or of a lubricant, comprising an esterification product of at least one branched monoalcohol with at least one polycarboxylic acid, characterized in that the branched monoalcohol and/or the polycarboxylic acid originates from renewable raw materials and the at least one branched monoalcohol has a terminal iso branch.

69. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid originates from renewable raw materials.

70. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid is saturated.

71. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid is unbranched.

72. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid is branched.

73. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid has 6-13 carbon atoms, preferably 8-13 carbon atoms.

74. The ester oil as claimed in claim 68, characterized in that the polycarboxylic acid comprises a dicarboxylic acid.

75. The ester oil as claimed in claim 74, characterized in that the dicarboxylic acid comprises adipic acid, trimethyladipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and/or brassylic acid.

76. The ester oil as claimed in claim 68, characterized in that the at least one monoalcohol originates from renewable raw materials.

77. The ester oil as claimed in claim 68, characterized in that the at least one monoalcohol is saturated.

78. The ester oil as claimed in claim 68, characterized in that the at least one monoalcohol has 6-24, preferably 8-16, carbon atoms, and the at least one monoalcohol more preferably has 9, 11, 12, 14 and/or 16 carbon atoms.

79. The ester oil as claimed in claim 68, characterized in that the at least one monoalcohol is a fatty alcohol.

80. The ester oil as claimed in claim 68, characterized in that the at least one monoalcohol comprises methyltetradecanol.

81. The ester oil as claimed in claim 68, characterized in that the esterification product, based on the carbon content, is formed to an extent of at least 50 mol %, preferably at least 60 mol %, even further preferably at least 70 mol %, from renewable raw materials.

82. The ester oil as claimed in claim 68, characterized in that a molecular weight of the esterification product is at least 400 g/mol, especially 550 g/mol.

83. The ester oil as claimed in claim 68, characterized in that the esterification product has at least 30 carbon atoms and/or at most 50 carbon atoms.

84. The use of an ester oil as claimed in claim 68 as a lubricant and/or hydraulic oil.

85. A lubricant and/or hydraulic oil comprising an ester oil as claimed in claim 68.

86. The lubricant and/or hydraulic oil as claimed in claim 85, characterized in that the proportion of ester oil is at least 50% by weight, preferably at least 75% by weight, further preferably at least 90% by weight, of the total weight of the lubricant and/or hydraulic oil.

87. The lubricant and/or hydraulic oil as claimed in claim 85, characterized in that additives are present, the additives present being antioxidants, antiwear additives, metal deactivators, corrosion inhibitors and/or antifoams.

88. A process for preparing an ester oil, especially for use in a hydraulic oil and/or a lubricant, by reacting a branched monoalcohol with a polycarboxylic acid to give an ester oil, characterized in that the branched monoalcohol and/or the polycarboxylic acid originate from renewable raw materials and the at least one branched monoalcohol has a terminal iso branch.

89. The process as claimed in claim 88, characterized in that the alcohols and/or carboxylic acids are prepared from fatty acids from renewable raw materials.

Patent History
Publication number: 20130190217
Type: Application
Filed: Aug 25, 2011
Publication Date: Jul 25, 2013
Applicant: PANOLIN Holding AG (Madetswil)
Inventors: Patrick Lämmle (Madetswil), Bernardo Walterspiel (Kreuzlingen), Mathias Woydt (Berlin-Dahlem)
Application Number: 13/818,636